HK1193918B - Methods and apparatuses for low -overhead wireless beacons having next full beacon time indications - Google Patents

Description

System and method for low overhead wireless beacon with next full beacon indication

Cross Reference to Related Applications

The present application claims U.S. provisional application N0.61/506,136 filed on 7/10/2011; U.S. provisional application N0.61/531,522 filed on 6/9/2011; U.S. provisional application N0.61/549,638 filed on 20/10/2011; U.S. provisional application N0.61/568,075 filed on 7/12/2011; U.S. provisional application N0.61/578,027 filed on 20/12/2011; U.S. provisional application N0.61/583,890 filed on 6/1/2012; U.S. provisional application N0.61/584,174 filed on 6/1/2012; U.S. provisional application N0.61/585,044 filed on month 10, 2012; U.S. provisional application N0.61/596,106 filed on 7/2/2012; U.S. provisional application N0.61/596,775 filed on 9/2/2012; U.S. provisional application N0.61/606,175 filed on 3/2/2012; U.S. provisional application N0.61/618,966 filed on 4/2/2012; and U.S. provisional application N0.61/620,869 filed on 5.4/2012, the entire contents of which are expressly incorporated herein by reference. This application relates to U.S. application No.13/544,896 (attorney docket No. 112733U1) entitled "SYSTEMS and METHODS FOR LOW-OVERHEAD WIRELESS BEACONS with COMPRESSED network identifiers" filed on 7, 9, 2012 and U.S. application No.13/544,900 (attorney docket No. 112733U3) filed on 7, 9, 2012 (same date) entitled "SYSTEMS AND hods lower-OVERHEAD WIRELESS BEACON TIMING", both of which are incorporated herein by reference in their entirety.

Background

Technical Field

The present application relates generally to wireless communications, and more particularly to systems, methods, and devices for compressing wireless beacons.

Background

In many telecommunication systems, a communication network is used to exchange messages between several spatially separated interacting devices. Networks may be classified according to geographic scope, which may be, for example, a city area, a local area, or a personal area. Such networks may be designated as Wide Area Networks (WANs), Metropolitan Area Networks (MANs), Local Area Networks (LANs), wireless Local Area Networks (LANs), or Personal Area Networks (PANs), respectively. The network also differs according to the switching/routing technology (e.g., circuit-switched-packet-switched), the type of physical medium used for transmission (e.g., wired-wireless), and the communication protocol suite used (e.g., internet protocol suite, SONET (synchronous optical networking), ethernet, etc.) used to interconnect the various network nodes and devices.

Wireless networks tend to be preferred when network elements are mobile and thus have dynamic connectivity requirements, or where the network architecture is formed in an ad hoc (ad hoc) topology rather than a fixed topology. Wireless networks employ intangible physical media in an unguided propagation mode using electromagnetic waves in the radio, microwave, infrared, optical, etc. frequency bands. Wireless networks advantageously facilitate user mobility and rapid field deployment when compared to fixed wired networks.

Devices in a wireless network may transmit/receive information between each other. The information may include packets, which may be referred to in some aspects as data units or data frames. The packet may include overhead information (e.g., header information, packet properties, etc.) that helps route the packet through the network, identify data in the packet, process the packet, etc., as well as data (e.g., user data, multimedia content, etc.) that may be carried in the packet's payload.

The access point may also broadcast beacon signals to other nodes to help the nodes synchronize timing or provide other information or functionality. Beacons may thus communicate a large amount of data, only some of which may be used by a given node. Accordingly, transmitting data in such beacons may be inefficient due to the fact that much of the bandwidth used to transmit the beacon may be used to transmit data that will not be used. Accordingly, improved systems, methods, and devices for communicating packets are desired.

Disclosure of Invention

The system, method, and apparatus of the present invention each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of the invention as expressed by the claims which follow, some features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled "detailed description" one will understand how the features of this invention provide advantages that include reducing the size of the wireless beacon frame, thereby reducing overhead in transmitting beacon signals.

One aspect of the present disclosure provides a method of communicating in a wireless network. The method includes generating a compressed beacon. The compressed beacon includes a Next Full Beacon Time Indication (NFBTI). The method further includes transmitting the compressed beacon at the access point.

Another aspect of the present invention provides a method of communicating in a wireless network. The method includes receiving, at a wireless device, a compressed beacon including a Next Full Beacon Time Indication (NFBTI). The method also includes operating the wireless device in a first power mode for a duration based on the next full beacon time indication. The method further includes transitioning the wireless device to a second power mode at the end of the duration. The wireless device consumes a first power when in a first power mode and a second power when in a second power mode. The first power is lower than the second power.

Another aspect of the invention provides a wireless device configured to communicate in a wireless network. The wireless device includes a processor configured to generate a compressed beacon. The compressed beacon includes a Next Full Beacon Time Indication (NFBTI). The wireless device also includes a transmitter configured to transmit the compressed beacon.

Another aspect of the invention provides a wireless device configured to communicate in a wireless network. The wireless device includes a receiver configured to receive a compressed beacon. The compressed beacon includes a Next Full Beacon Time Indication (NFBTI). The wireless device also includes a processor configured to operate the wireless device in a first power mode for a duration based on the next full beacon time indication. The processor is further configured to transition the wireless device to a second power mode at the end of the duration. The wireless device consumes a first power when in a first power mode and a second power when in a second power mode. The first power is lower than the second power.

Another aspect of the present invention provides an apparatus for communicating in a wireless network. The apparatus includes means for generating a compressed beacon. The compressed beacon includes a Next Full Beacon Time Indication (NFBTI). The apparatus also includes means for transmitting the compressed beacon.

Another aspect of the present invention provides an apparatus for communicating in a wireless network. The apparatus includes means for receiving a compressed beacon. The compressed beacon includes a Next Full Beacon Time Indication (NFBTI). The apparatus also includes means for operating the wireless device in a first power mode for a duration based on the next full beacon time indication. The apparatus further includes means for transitioning the wireless device to a second power mode at the end of the duration. The wireless device consumes a first power when in a first power mode and a second power when in a second power mode. The first power is lower than the second power.

Another aspect of the invention provides a non-transitory computer-readable medium comprising code that, when executed, causes an apparatus to generate a compressed beacon. The compressed beacon includes a Next Full Beacon Time Indication (NFBTI). The medium further includes code that, when executed, causes the apparatus to transmit the compressed beacon.

Another aspect of the invention provides a non-transitory computer-readable medium comprising code that, when executed, causes an apparatus to receive a compressed beacon. The compressed beacon includes a Next Full Beacon Time Indication (NFBTI). The medium further includes code that, when executed, causes the apparatus to operate the wireless device in a first power mode for a duration based on the next full beacon time indication. The medium further includes code that, when executed, causes the apparatus to transition the wireless device to a second power mode at an end of the duration. The wireless device consumes a first power when in a first power mode and a second power when in a second power mode. The first power is lower than the second power.

Drawings

Fig. 1 illustrates an example of a wireless communication system in which various aspects of the present disclosure may be employed.

Fig. 2 illustrates various components, including a receiver, that may be utilized in a wireless device employed within the wireless communication system of fig. 1.

Fig. 3 illustrates an example of a beacon frame used in a legacy system for communication.

Fig. 4 illustrates an example low overhead beacon frame.

Fig. 5 illustrates another example low overhead beacon frame.

Fig. 6 is a timing diagram illustrating exemplary beacon timing.

Fig. 7 illustrates a flow diagram of an example method for generating a compressed (or low overhead) beacon.

Fig. 8 is a functional block diagram of an exemplary wireless device that may be employed within the wireless communication system of fig. 1.

Fig. 9 illustrates a flow diagram of an example method for processing compressed (or low overhead) beacons.

Fig. 10 is a functional block diagram of another exemplary wireless device that may be employed within the wireless communication system of fig. 1.

Fig. 11 illustrates a flow diagram of another exemplary method for generating a compressed (or low overhead) beacon.

Fig. 12 is a functional block diagram of another exemplary wireless device that may be employed within the wireless communication system of fig. 1.

Fig. 13 shows a flow diagram of an exemplary method for operating the wireless device of fig. 2.

Fig. 14 is a functional block diagram of another exemplary wireless device that may be employed within the wireless communication system of fig. 1.

Fig. 15 illustrates a flow chart of an example method for communicating in the wireless communication system of fig. 1.

Fig. 16 is a functional block diagram of another exemplary wireless device that may be employed within the wireless communication system of fig. 1.

Fig. 17 illustrates a flow diagram of another example method for communicating in the wireless communication system of fig. 1.

Fig. 18 is a functional block diagram of another exemplary wireless device that may be employed within the wireless communication system of fig. 1.

Detailed Description

Various aspects of the novel systems, devices, and methods are described more fully hereinafter with reference to the accompanying drawings. This summary disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the present disclosure is intended to cover any aspect of the novel systems, apparatuses, and methods disclosed herein, whether implemented independently or in combination with any other aspect of the present invention. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. Moreover, the scope of the present application is intended to cover apparatuses or methods practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the present invention set forth herein. It should be understood that any aspect disclosed herein may be implemented by one or more elements of a claim.

Although specific aspects are described herein, numerous variations and permutations of these aspects are within the scope of the present disclosure. Although some benefits and advantages of the preferred aspects are mentioned, the scope of the present disclosure is not intended to be limited to a particular benefit, use, or objective. Rather, aspects of the disclosure are intended to be broadly applicable to different wireless technologies, system configurations, networks, and transmission protocols, some of which are illustrated by way of example in the figures and the following description of the preferred aspects. The detailed description and drawings are merely illustrative of the disclosure rather than limiting, the scope of the disclosure being defined by the appended claims and equivalents thereof.

Popular wireless network technologies may include various types of Wireless Local Area Networks (WLANs). WLANs may be used to interconnect nearby devices together using widely used networking protocols. The various aspects described herein may be applied to any communication standard, such as WiFi, or more generally any member of the IEEE 802.11 family of wireless protocols. For example, various aspects described herein may be used as part of an IEEE 802.11ah protocol using frequency bands below 1 GHz.

In some aspects, wireless signals in the sub-gigahertz band may be transmitted according to the 802.11ah protocol using Orthogonal Frequency Division Multiplexing (OFDM), Direct Sequence Spread Spectrum (DSSS) communications, a combination of OFDM and DSSS communications, or other schemes. Implementations of the 802.11ah protocol may be used for sensor, metering, and smart grid networks. Advantageously, aspects of certain devices implementing the 802.11ah protocol may consume less power than devices implementing other wireless protocols and/or may be used to transmit wireless signals across relatively long distances (e.g., about 1 kilometer or more).

In some implementations, a WLAN includes various devices that are components of an access wireless network. For example, there may be two types of devices: an access point ("AP") and a client (also referred to as a station, or "STA"). Generally, the AP serves as a hub or base station for the WLAN, while the STA serves as a user of the WLAN. For example, the STA may be a laptop computer, a Personal Digital Assistant (PDA), a mobile phone, and the like. In an example, the STA connects to the AP via a wireless link that is WiFi compliant (e.g., IEEE 802.11 protocol, such as 802.11ah) to obtain general connectivity to the internet or to other wide area networks. In some implementations, the STA may also be used as an AP.

An access point ("AP") may also include, be implemented as, or be referred to as a node B, a radio network controller ("RNC"), an evolved node B, a base station controller ("BSC"), a base transceiver station ("BTS"), a base station ("BS"), a transceiver function ("TF"), a radio router, a radio transceiver, or some other terminology.

A station ("STA") may also include, be implemented as, or be referred to as an access terminal ("AT"), a subscriber station, a subscriber unit, a mobile station, a remote terminal, a user agent, a user device, user equipment, or some other terminology. In some implementations, an access terminal may comprise a cellular telephone, a cordless telephone, a session initiation protocol ("SIP") phone, a wireless local loop ("WLL") station, a personal digital assistant ("PDA"), a handheld device having wireless connection capability, or some other suitable processing device connected to a wireless modem. Accordingly, one or more aspects taught herein may be incorporated into a phone (e.g., a cellular phone or smart phone), a computer (e.g., a laptop), a portable communication device, a handset, a portable computing device (e.g., a personal data assistant), an entertainment device (e.g., a music or video device, or a satellite radio), a gaming device or system, a global positioning system device, or any other suitable device configured to communicate via a wireless medium.

As discussed above, certain devices described herein may implement, for example, the 802.11ah standard. Such devices, whether used as STAs or APs or other devices, may be used for smart metering or in smart grid networks. Such devices may provide sensor applications or be used in home automation. These devices may alternatively or additionally be used in a healthcare environment, for example for personal healthcare. These devices may also be used for supervision to enable extended range internet connectivity (e.g., for use with hotspots), or to enable machine-to-machine communication.

Fig. 1 illustrates an example of a wireless communication system 100 in which aspects of the present disclosure may be employed. The wireless communication system 100 may operate in accordance with a wireless standard, such as the 802.11ah standard. The wireless communication system 100 may include an AP104 in communication with STAs 106.

Various procedures and methods may be used for transmissions between the AP104 and the STA106 in the wireless communication system 100. For example, signals may be transmitted and received between the AP104 and the STAs 106 according to OFDM/OFDMA techniques. If this is the case, the wireless communication system 100 may be referred to as an OFDM/OFDMA system. Alternatively, signals may be transmitted and received between the AP104 and the STA106 according to CDMA techniques. If this is the case, the wireless communication system 100 may be referred to as a CDMA system.

The communication link that facilitates transmission from AP104 to one or more STAs 106 may be referred to as Downlink (DL)108, while the communication link that facilitates transmission from one or more STAs 106 to AP104 may be referred to as Uplink (UL) 110. Alternatively, downlink 108 may be referred to as the forward link or forward channel, and uplink 110 may be referred to as the reverse link or reverse channel.

AP104 may act as a base station and provide wireless communication coverage in a Basic Service Area (BSA) 102. The AP104, along with STAs 106 associated with the AP104 and communicating using the AP104, may be referred to as a Basic Service Set (BSS). It should be noted that the wireless communication system 100 may not have a central AP104, but may function as a peer-to-peer network between STAs 106. Accordingly, the functions of the AP104 described herein may alternatively be performed by one or more STAs 106.

The AP104 may transmit beacon signals (or simply "beacons") to other nodes of the system 100 via a communication link, such as the downlink 108, which may help other nodes STAs 106 synchronize their timing with the AP104, or may provide other information or functionality. Such beacons may be transmitted periodically. In an aspect, the period between successive transmissions may be referred to as a superframe. The transmission of beacons may be divided into groups or intervals. In an aspect, the beacon may include, but is not limited to, information such as: setting timestamp information of a common clock, a peer-to-peer network identifier, a device identifier, capability information, a superframe duration, transmit direction information, receive direction information, a neighbor list, and/or an extended neighbor list, some of which are described in more detail below. Thus, a beacon may include both information that is common (e.g., shared) among several devices, as well as information that is specific to a given device.

In some aspects, a STA may be required to associate with an AP to send and/or receive communications to and/or from the AP. In an aspect, the information for associating is included in a beacon broadcast by the AP. To receive such beacons, for example, the STA may perform a wide coverage search over the coverage area. For example, the search may also be performed by the STA by sweeping the coverage area in a lighthouse fashion. After receiving the information for associating, the STA may transmit a reference signal, such as an association probe or request, to the AP. In some aspects, an AP may use backhaul services, for example, to communicate with a larger network, such as the internet or a Public Switched Telephone Network (PSTN).

Fig. 2 illustrates various components that may be employed in a wireless device 202 employed within the wireless communication system 100. Wireless device 202 is an example of a device that may be configured to implement the various methods described herein. For example, the wireless device 202 may include the AP104 or one of the STAs 106.

The wireless device 202 may include a processor 204 that controls the operation of the wireless device 202. The processor 204 may also be referred to as a Central Processing Unit (CPU). Memory 206, which may include both Read Only Memory (ROM) and Random Access Memory (RAM), provides instructions and data to the processor 204. A portion of the memory 206 may also include non-volatile random access memory (NVRAM). The processor 204 typically performs logical and arithmetic operations based on program instructions stored within the memory 206. The instructions in the memory 206 may be executable to implement the methods described herein.

When wireless device 202 is implemented or functions as an AP, processor 204 may be configured to select one of a plurality of beacon types and generate a beacon signal having such a beacon type. For example, the processor 204 may be configured to generate a beacon signal including beacon information and determine what type of beacon information to use, as discussed in further detail below.

When the wireless device 202 is implemented as or functions as a STA, the processor 204 may be configured to process beacon signals of a plurality of different beacon types. For example, the processor 204 may be configured to determine the beacon type used in the beacon signal and process the beacons and/or fields in the beacon signal accordingly, as discussed further below.

The processor 204 may include or be a component of a processing system implemented with one or more processors. The one or more processors may be implemented with any combination of general purpose microprocessors, microcontrollers, Digital Signal Processors (DSPs), Field Programmable Gate Arrays (FPGAs), Programmable Logic Devices (PLDs), controllers, state machines, gated logic, discrete hardware components, dedicated hardware finite state machines, or any other suitable entity capable of performing a calculation or other manipulation of information.

The processing system may also include a machine-readable medium for storing the software. Software should be construed broadly to mean any type of instructions, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The instructions may include code (e.g., in source code format, binary code format, executable code format, or any other suitable code format). The instructions, when executed by the one or more processors, cause the processing system to perform the various functions described herein.

The wireless device 202 may also include a housing 208, and the housing 208 may include a transmitter 210 and/or a receiver 212 to allow transmission and reception of data between the wireless device 202 and a remote location. The transmitter 210 and receiver 212 may be combined into a transceiver 214. An antenna 216 may be attached to the housing 208 and electrically coupled to the transceiver 214. The wireless device 202 may also include (not shown) multiple transmitters, multiple receivers, multiple transceivers, and/or multiple antennas.

The transmitter 210 may be configured to wirelessly transmit beacon signals having different beacon types. For example, the transmitter 210 may be configured to transmit beacon signals having different beacon types generated by the processor 204, as discussed above.

The receiver 212 may be configured to wirelessly receive beacon signals having different beacon types. In some aspects, the receiver 212 is configured to detect the type of beacon used and process the beacon signal accordingly, as discussed in further detail below.

The wireless device 202 may also include a signal detector 218 that may be used in an effort to detect and quantify the level of signals received by the transceiver 214. The signal detector 218 may detect signals such as total energy, energy per subcarrier per symbol, power spectral density, and other signals. The wireless device 202 may also include a Digital Signal Processor (DSP)220 for use in processing signals. DSP220 may be configured to generate packets for transmission. In some aspects, the packet may include a physical layer data unit (PPDU).

In some aspects, the wireless device 202 may further include a user interface 222. The user interface 222 may include a keypad, a microphone, a speaker, and/or a display. User interface 222 may include any element or component that conveys information to a user of wireless device 202 and/or receives input from the user.

In some aspects, the wireless device 202 may further include a power supply 230. The power supply 230 may include a wired power supply, a battery, a capacitor, and the like. The power supply 230 may be configured to provide various levels of power output. In some embodiments, other components of wireless device 202 may be configured to enter one or more different power consumption states. For example, the processor 204 may be configured to operate in a high power mode or a low power mode. Likewise, the transmitter 219 and receiver 212 may be capable of operating in various power states, which may include a disabled state, a full power state, and one or more states therebetween. In particular, the device 202 as a whole may be configured to enter a relatively low power state between transmissions and a relatively high power state at one or more determined times.

The various components of the wireless device 202 may be coupled together by a bus system 226. The bus system 226 may include, for example, a data bus, as well as a power bus, a control signal bus, and a status signal bus in addition to the data bus. Those skilled in the art will appreciate that the components of the wireless device 202 may be coupled together or use some other mechanism to accept or provide input to each other.

Although several separate components are illustrated in fig. 2, those skilled in the art will recognize that one or more of these components may be combined or implemented collectively. For example, the processor 204 may be used to implement not only the functionality described above with respect to the processor 204, but also the functionality described above with respect to the signal detector 218 and/or the DSP 220. In addition, each of the components illustrated in fig. 2 may be implemented using a plurality of separate elements.

As discussed above, the wireless device 202 may comprise an AP104 or STA106 and may be used to transmit and/or receive communications including beacon signals. For ease of reference, when wireless device 202 is configured as an AP, it is referred to hereinafter as wireless device 202 a. Similarly, when the wireless device 202 is configured as a STA, it is referred to hereinafter as wireless device 202 s.

Fig. 3 illustrates an example of a beacon frame 300 used in a legacy system for communication. As shown, the beacon 300 includes a Medium Access Control (MAC) header 302, a frame body 304, and a Frame Control Sequence (FCS) 306. As shown, the MAC header 302 is 24 bytes long, the frame body 304 is variable in length, and the FCS 306 is 4 bytes long.

The MAC header 302 is used to provide basic routing information about the beacon frame 300. In the illustrated embodiment, the MAC header 302 includes a Frame Control (FC) field 308, a duration field 310, a Destination Address (DA) field 312, a Source Address (SA) field 314, a Basic Service Set Identification (BSSID) field 316, and a sequence control field 318. As shown, FC field 308 is 2 bytes long, duration field 310 is 2 bytes long, DA field 312 is 6 bytes long, SA field 314 is 6 bytes long, BSSID field 316 is 6 bytes long, and sequence control field 318 is 2 bytes long.

The frame body 304 is used to provide detailed information about the transmitting node. In the illustrated embodiment, the frame body 304 includes a timestamp field 320, a beacon interval field 322, a capability information field 324, a Service Set Identifier (SSID) field 326, a supported rate field 328, a Frequency Hopping (FH) parameter set 330, a direct sequence parameter set 332, a contention-free parameter set 334, an Independent Basic Service Set (IBSS) parameter set 336, a country information field 338, a FH hopping parameter field 340, an FH mode table 342, a power constraint field 344, a channel switch announcement field 346, a silence field 348, an IBSS direct sequence selection (DFS) field 350, a Transmit Power Control (TPC) field 352, an Effective Radiated Power (ERP) information field 354, an extended supported rate field 356, and a Robust Security Network (RSN) field 358.

As shown in fig. 3, the timestamp field 320 is 8 bytes in length, the beacon interval field 322 is 2 bytes in length, the capability information field 324 is 2 bytes in length, the Service Set Identifier (SSID) field 326 is variable in length, the supported rate field 328 is variable in length, the Frequency Hopping (FH) parameter set 330 is 7 bytes in length, the direct sequence parameter set 332 is 2 bytes in length, the contention-free parameter set 334 is 8 bytes in length, the Independent Basic Service Set (IBSS) parameter set 336 is 4 bytes in length, the country information field 338 is variable in length, the FH hopping parameter field 340 is 4 bytes in length, the FH mode table 342 is variable in length, the power constraint field 344 is 3 bytes in length, the channel switch announcement field 346 is 6 bytes in length, the silence field 348 is 8 bytes in length, the IBSS direct sequence selection (DFS) field 350 is variable in length, the Transmit Power Control (TPC) field 352 is 4 bytes in length, the Effective Radiated Power (ERP) information field 354 is 3 bytes in length, the extended supported rate field 356 is variable in length, and the Robust Secure Network (RSN) field 358 is variable in length.

Still referring to fig. 3, although the beacon frame 300 is variable in length, it is always at least 89 bytes in length. In various radio environments, much of the information included in the beacon frame 300 may be used infrequently or not at all. Accordingly, in a low power radio environment, it may be desirable to reduce the length of the beacon frame 300 in order to reduce power consumption. Furthermore, some radio environments use low data rates. For example, an access point implementing the 802.11ah standard may take a relatively long time to transmit the beacon frame 300 due to a relatively low data transmission rate. Accordingly, it may be desirable to reduce the length of the beacon frame 300 to shorten the amount of time to transmit the beacon frame 300.

There are several ways by which the beacon frame 300 may be shortened or compressed. In one embodiment, one or more fields of the beacon frame 300 may be omitted. In another embodiment, the size of one or more fields of the beacon frame 300 may be reduced, for example, by using a different encoding scheme or by accepting lower information content. In one embodiment, the wireless system may allow the STA to query the AP for information omitted from the beacon. For example, the STA may request information omitted from the beacon via a probe request. In one embodiment, the full beacon may be transmitted periodically or at dynamically selected times.

Fig. 4 illustrates an example low overhead beacon frame 400. In the illustrated embodiment, the low-overhead beacon frame 400 includes a Frame Control (FC) field 410, a Source Address (SA) field 420, a timestamp 430, a change sequence field 440, a Next Full Beacon Time Indication (NFBTI)450, a compressed SSID field 460, an access network options field 470, an optional IE field 480, and a Cyclic Redundancy Check (CRC) field 490. As shown, the Frame Control (FC) field 410 is 2 bytes long, the Source Address (SA) field 420 is 6 bytes long, the timestamp 430 is 4 bytes long, the change sequence field 440 is 1 byte long, the duration to the next full beacon 450 is 3 bytes long, the compressed SSID field 460 is 4 bytes long, the access network options field 470 is 1 byte long, and the Cyclic Redundancy Check (CRC) field 490 is 4 bytes long.

In various embodiments, low overhead beacon frame 400 may omit one or more fields shown in fig. 4 and/or include one or more fields not shown in fig. 4 (including any fields discussed herein). In particular, in various embodiments, one or more of the next full beacon time indication 450, the compressed SSID field 460, and the access network options field 470 may be omitted according to one or more flags in the frame control field 410. One of ordinary skill in the art will appreciate that the fields in the low overhead beacon frame 400 may be of different suitable lengths and may be in different orders.

The Destination Address (DA) field 312 described above with respect to fig. 3 may be omitted from the low-overhead beacon frame 400 because the beacon frame 400 may be broadcast. Thus, there is no need to identify a specific destination address. Similarly, BSSID field 316 may be omitted. In one embodiment, SA field 420 may include a BSSID. The duration field 310 may also be omitted. In one embodiment, if a Network Allocation Vector (NAV) is desired after transmitting the low-overhead beacon frame 400, the NAV may be signaled using a short interframe space (SIFS) after transmitting the beacon frame 400. Further, the sequence control field 318 may be omitted from the low overhead beacon frame 400 because sequence control may not be necessary in the beacon.

In the illustrated embodiment, the Frame Control (FC) field 410 includes a 2-bit version field 411, a 2-bit type field 412, a 4-bit subtype field 413, a 1-bit next full beacon time indication present flag 414, a 1-bit SSID present flag 415, a 1-bit internetworking present flag 416, a 3-bit Bandwidth (BW) field 417, a 1-bit security flag 418, and one Reserved (RSVD) bit 419. In various embodiments, FC field 410 may omit one or more fields shown in fig. 4 and/or include one or more fields not shown in fig. 4 (including any fields discussed herein). One of ordinary skill in the art will appreciate that the fields in the beacon FC field 410 may be of different suitable lengths and may be in different orders.

In one embodiment, the Frame Control (FC) field 410 contains a flag indicating that the beacon frame 400 is a Low Overhead Beacon (LOB), also referred to as a "short beacon". In one embodiment, the FC field 410 may indicate that the beacon frame 400 is a short beacon by setting the type field 412 to "11" (which may indicate a beacon frame) and by setting the subtype field 413 to "0001" (which may indicate that the beacon is compressed, low overhead, and/or "short"). When a STA receives a beacon frame 400, it may decode the FC field 410, which contains a flag indicating that the beacon frame 400 is a short beacon. Accordingly, the STA may decode the beacon frame 400 according to the format described herein.

The next full beacon time indication present flag 414 shown in fig. 4 includes 1 bit. In some implementations, the next full beacon time indication present flag 414 may include more than 1 bit. In some implementations, the next full beacon time indication present flag 414 may include a configurable number of bits. For example, the length of the next full beacon time presence indication field 414 may be associated with a device-specific characteristic (such as a service set, a device type), or a value stored in memory.

The value included in the next full beacon time indication present flag 414 may be used to identify that the next full beacon time indication field 450 is included in the low overhead beacon frame 400. Thus, when a transmitting device, such as AP104 (fig. 1), is configured to transmit a next full beacon time indication field 450 and will include the next full beacon time indication field 450 in the transmitted frame, the transmitting device may set the value in the next full beacon time indication present flag 414. For example, in the implementation shown in fig. 4, the next full beacon time indication present flag 414, which comprises 1 bit, may set the value of the next full beacon time indication present flag 414 to "1" to indicate that the low overhead beacon frame 400 includes the next full beacon time indication field 450. In turn, the transmitting device may be configured to set the value of the next full beacon time indication present flag 414 to "0" to indicate that the low overhead beacon frame 400 does not include the next full beacon time indication field 450.

In some implementations, the "presence" of the next full beacon time indication field may also include whether the value included in the next full beacon time indication field is an operational value. For example, in some implementations, if the transmitting device is not configured to generate the next full beacon time indication value for each signal, the transmitting device may set the value of this field to an arbitrary value (e.g., random, constant, null). Accordingly, setting the presence value such that an indication of "not present" is provided may mean in some implementations that the field is included in the frame, but that the value contained in the field is not operational (e.g., arbitrary).

A receiving device, such as STA106 (fig. 1), may process frame control field 410 to determine whether the received frame includes next full beacon time indication field 450 by identifying the value included in next full beacon time indication present flag 414. For example, in the implementation shown in fig. 4, the next full beacon time indication present flag 414, which comprises 1 bit, may set the value of the next full beacon time indication present flag 414 to "1" to indicate that the low overhead beacon frame 400 includes the next full beacon time indication field 450. In turn, the value of the next full beacon time indication present flag 414 may be set to "0" to indicate that the low overhead beacon frame 400 does not include the next full beacon time indication field 450. In some implementations, the receiving device may change the processing of the low overhead beacon frame 400 based on whether the low overhead beacon frame 400 includes the next full beacon time indication field 450. For example, if the receiving device identifies whether the frame includes the next full beacon time indication field 450 through processing of the next full beacon time indication present flag 414 included in the frame control field 410, the appropriate signal processor may be configured to process the frame with or without the next full beacon time indication field 450. This may improve processing of the frame because the receiving device may identify characteristics of the frame (e.g., the presence of the next full beacon time indication) without first processing the entire frame.

The SSID present flag 415 shown in fig. 4 includes 1 bit. In some implementations, SSID present flag 415 may include more than 1 bit. In some implementations, the SSID present flag 415 may include a configurable number of bits. For example, the length of the SSID present flag 415 may be associated with a device-specific characteristic (such as a service set, a device type), or a value stored in memory.

The value included in the SSID present field 415 may be used to identify that the compressed SSID field 460 is included in the low-overhead beacon frame 400. For example, in some implementations, the SSID may be hidden or covered. Accordingly, when a transmitting device, such as AP104 (fig. 1), is configured to transmit a compressed SSID field 460 and will include the compressed SSID field 460 in the transmitted frame, the transmitting device may set the value in the SSID present flag 415. For example, in the implementation shown in fig. 4, the SSID present flag 415 comprising 1 bit may set the value of the SSID present flag 415 to "1" to indicate that the low-overhead beacon frame 400 includes a compressed SSID field 460. In turn, the transmitting device may be configured to set the value of the SSID present flag 415 to "0" to indicate that the low-overhead beacon frame 400 does not include the compressed SSID field 460.

In some implementations, the "presence" of the compressed SSID field may also include whether a value included in the compressed SSID field is an operational value. For example, in some implementations, if the transmitting device is not configured to generate a compressed SSID field value for each signal, the transmitting device may set the value of this field to an arbitrary value (e.g., random, constant, null). Accordingly, setting the presence value such that an indication of "not present" is provided may mean in some implementations that the field is included in the frame, but that the value contained in the field is not operational (e.g., arbitrary).

A receiving device, such as STA106 (fig. 1), may process frame control field 410 to determine whether the received frame includes compressed SSID field 460 by identifying the value included in SSID present flag 415. For example, in the implementation shown in fig. 4, the SSID present flag 415 comprising 1 bit may set the value of the SSID present flag 415 to "1" to indicate that the low-overhead beacon frame 400 includes a compressed SSID field 460. In turn, the value of the SSID present flag 415 may be set to "0" to indicate that the low-overhead beacon frame 400 does not include the compressed SSID field 460. In some implementations, the receiving device may change the processing of the low-overhead beacon frame 400 based on whether the low-overhead beacon frame 400 includes the compressed SSID field 460. For example, if the receiving device identifies whether the frame includes a compressed SSID field 460 through processing of an SSID present flag 415 included in the frame control field 410, the appropriate signal processor may be configured to process the frame with or without the compressed SSID field 460. This may improve processing of the frame because the receiving device may identify characteristics of the frame (e.g., the presence of the compressed SSID field) without first processing the entire frame.

In one embodiment, the AP may set the compressed SSID field 460 to a reserved value to indicate that the SSID is hidden. For example, when the SSID is hidden, the compressed SSID field 460 may have all-zero, all-1, etc. values. If the SSID hashes to a reserved value when computed using the SSID hashing function, the hashed SSID can be remapped to another value (e.g., a constant value) or to an alternate value using an alternate hashing function. In another embodiment, the FC field 410 may include an indication that the SSID is hidden.

The internetwork presence flag 416 shown in fig. 4 includes 1 bit. In some implementations, the internetwork presence flag 416 may include more than 1 bit. In some implementations, the internetworking presence flag 416 may include a configurable number of bits. For example, the length of the next full beacon time presence indication field 414 may be associated with a device-specific characteristic (such as a service set, a device type), or a value stored in memory.

The value included in the internetworking presence flag 416 may be used to identify that the access network options field 470 is included in the low-overhead beacon frame 400. Accordingly, when a transmitting device, such as AP104 (fig. 1), is configured to transmit access network option field 470 and will include the access network option field 470 in the transmitted frame, the transmitting device may set the value in internetworking present flag 416. For example, in the implementation shown in fig. 4, the internetworking present flag 416, which comprises 1 bit, may set the value of the internetworking present flag 416 to "1" to indicate that the low overhead beacon frame 400 includes the access network option field 470. In turn, the transmitting device may be configured to set the value of the internetworking present flag 416 to "0" to indicate that the low overhead beacon frame 400 does not include the access network option field 470.

In some implementations, the "presence" of the access network options field may also include whether the value included in the access network options field is an operational value. For example, in some implementations, if the transmitting device is not configured to generate an access network option value for each signal, the transmitting device may set the value of this field to an arbitrary value (e.g., random, constant, null). Accordingly, setting the presence value such that an indication of "not present" is provided may mean in some implementations that the field is included in the frame, but that the value contained in the field is not operational (e.g., arbitrary).

A receiving device, such as STA106 (fig. 1), may process frame control field 410 to determine whether the received frame includes access network option field 470 by identifying the value included in internetworking present flag 416. For example, in the implementation shown in fig. 4, the internetworking present flag 416, which comprises 1 bit, may set the value of the internetworking present flag 416 to "1" to indicate that the low overhead beacon frame 400 includes the access network option field 470. In turn, the value of the internetworking presence flag 416 may be set to "0" to indicate that the low overhead beacon frame 400 does not include the access network option field 470. In some implementations, the receiving device may change the processing of the low overhead beacon frame 400 based on whether the low overhead beacon frame 400 includes the access network options field 470. For example, if the receiving device identifies whether the frame includes the access network option field 470 through processing of the internetworking present flag 416 included in the frame control field 410, the appropriate signal processor may be configured to process the frame with or without the access network option field 470. This may improve processing of the frame because the receiving device may identify characteristics of the frame (e.g., the presence of an access network option) without first processing the entire frame.

In one embodiment, the bandwidth field 417 is used to indicate the bandwidth of the AP104 (fig. 1). In one embodiment, the bandwidth field 417 may indicate a bandwidth of 2MHz multiplied by a binary value of the bandwidth field 417. For example, a value of "0001" may indicate a BSS of 2MHz, and a value of "0002" may indicate a BSS of 4 MHz. In one embodiment, a value of "0000" may indicate a BSS of 1 MHz. In various embodiments, other multipliers and/or encodings may be used.

The security flag 418 shown in fig. 4 includes 1 bit. In some implementations, the security flag 418 may include more than 1 bit. In some implementations, the security flag 418 may include a configurable number of bits. For example, the length of the security flag 418 may be associated with a device-specific characteristic (such as a service set, a device type), or a value stored in memory.

In one embodiment, the value included in the security flag 418 may be used to indicate whether the AP104 (fig. 1) uses data encryption. In one embodiment, details of a Robust Secure Network (RSN) may be obtained from the probe response. Accordingly, when a transmitting device, such as AP104 (fig. 1), is configured to use data encryption, the transmitting device may set a value in security flag 418. For example, in the implementation shown in fig. 4, a security flag 418 comprising 1 bit may set the value of the security flag 418 to "1" to indicate that the transmitting device is configured to use data encryption. In turn, the transmitting device may be configured to set the value of the security flag 418 to "0" to indicate that the transmitting device is not configured to use data encryption.

A receiving device, such as STA106 (fig. 1), may process frame control field 410 to determine whether the transmitting device is configured to use data encryption by identifying the value included in security flag 418. For example, in the implementation shown in fig. 4, a security flag 418 comprising 1 bit may set the value of the security flag 418 to "1" to indicate that the transmitting device is configured to use data encryption. In turn, the value of the security flag 418 may be set to "0" to indicate that the transmitting device is not configured to use data encryption. In some implementations, the receiving device may change the processing of the low overhead beacon frame 400 and/or other frames based on whether the transmitting device is configured to use data encryption. For example, if the receiving device identifies whether the transmitting device is configured to use data encryption through processing of a security flag 418 included in frame control field 410, the appropriate signal processor may be configured to process frames with or without encryption.

In the illustrated embodiment of fig. 4, timestamp field 430 is shorter than timestamp field 320 described above with respect to fig. 3. Specifically, timestamp field 430 is only 4 bytes in length, while timestamp field 320 is 8 bytes in length. Timestamp field 430 may include one or more least significant bits of a "full" timestamp (such as timestamp field 320). For example, timestamp field 430 may include the four least significant bytes of timestamp field 320.

In one embodiment, a STA receiving a low overhead beacon 400 may retrieve a full eight byte timestamp from the transmitting AP via a probe request. In one embodiment, the length of timestamp field 430 may be selected such that timestamp field 430 will not overflow more than once every seven minutes. In conventional systems, the timestamp field 320 value is interpreted as nanoseconds. In one embodiment, the timestamp field 430 value may be interpreted as a number of OFDM symbol periods. Accordingly, in embodiments where the OFDM symbol period is longer than one nanosecond, the timestamp field 430 may overflow less quickly.

In one embodiment, the timestamp field 430 may facilitate a Timing Synchronization Function (TSF) between the devices 104 and 106 in the wireless communication system 100. In an embodiment where AP104 updates timestamp field 430 at 1MHz, a 4 byte timestamp field 430 would overflow approximately every 72 minutes. In an embodiment where the device clock is driven at about +/-20ppm, driving for 30 minutes takes about 1.4 years. Thus, the device 106 may maintain time synchronization with the AP104 if it checks the beacon 400 as little as once per day.

In the illustrated embodiment of fig. 4, the change sequence field 440 may be used to provide a sequence number indicating a change in network information. In the illustrated embodiment, the change sequence field 440 is used to track changes to the AP 104. In one embodiment, AP104 may increment change sequence field 440 when one or more parameters of AP104 change. For example, the AP may transmit a full beacon when the SSID changes. In one embodiment, when the configuration of the AP104 changes, the AP104 may decrement the change sequence field 440, change the change sequence field 440 to a random or pseudo-random number, or otherwise modify the change sequence field 440. In various embodiments, change sequence field 440 may be referred to as a beacon index or beacon number.

The STA106 may be configured to detect a change in the change sequence field 440. When the STA106 detects a change in the change sequence field 440, the STA106 may wait for transmission of a full beacon. When the STA106 waits for the AP104 to transmit a full beacon, it may defer transitioning to the sleep or low power mode. In another embodiment, when the STA106 detects a change in the change sequence field 440, the STA106 may send a probe request frame to the AP 104. The AP104 may send the updated configuration information to the STA106 in response to the probe request frame.

Still referring to fig. 4, the next full beacon time indication 450 may be used to indicate the next time at which the AP104 will transmit a full beacon, such as beacon 300. Thus, in one embodiment, the STA106 may avoid probe request transmissions and may sleep while waiting for a full beacon. In various embodiments, the next full beacon time indication 450 may include one or more of: a flag indicating that a full beacon will follow, an absolute time that the AP104 will transmit a full beacon, and a duration until the AP104 will transmit a full beacon.

In the illustrated embodiment, the next full beacon time indication 450 may comprise a next full beacon time indicator. In one embodiment, the STA may use the elapsed next full beacon time indicator to determine when to wake up and receive a full beacon, thereby saving power. In the illustrated embodiment, the next full beacon time indicator comprises the 3 most significant bytes of the 4 least significant bytes of the next Target Beacon Transmit Time (TBTT) timestamp. In other words, the next full beacon time indication 450 may include bytes 1 through 4 of the next TBTT timestamp, with byte 0 omitted (with the lower bits leading). In one embodiment, the next full beacon time indication 450 may have a resolution in units of 46 μ s. In one embodiment, the AP104 may calculate the next TBTT in software and store the value in the frame. In various embodiments, the next full beacon time indication 450 may be encoded in other manners.

In one embodiment, the next full beacon time indication 450 may include a full beacon following flag. The full beacon follow flag may include 1 bit. In some implementations, the full beacon following flag may include more than 1 bit. In some implementations, the full beacon following flag may include a configurable number of bits. For example, the length of the security flag 418 may be associated with a device-specific characteristic (such as a service set, a device type), or a value stored in memory. The full beacon follow flag may be used to indicate that the AP104 will transmit a conventional beacon, such as the beacon frame 300 described above with respect to fig. 3, after transmitting the low overhead beacon 400. In one embodiment, when the configuration of the AP104 changes, the AP104 transmits a full beacon. For example, the AP104 may transmit a full beacon when the SSID changes.

In one embodiment, the next full beacon time indication 450 may include the duration to the next full beacon. The duration to the next full beacon may be used to indicate the number of Time Units (TUs) before the next full beacon. In one embodiment, the time unit may be 1024 μ s. In one embodiment, the duration to the next full beacon may indicate the number of time units before the next full beacon to within an accuracy of 1 TU. In one embodiment, the STA may use the duration to the next full beacon to determine the time to wake up and receive the full beacon, thereby saving power. In one embodiment, a preset value (such as a null value) in the next full beacon time indication 450 may indicate that the duration feature to the next full beacon is not supported or that the duration is not determined. For example, an all 0 value, an all 1 value, and/or any other predetermined value may indicate that the AP does not support the duration provided to the next full beacon, or that the duration is not determined. In various embodiments, the duration to the next full beacon may be encoded in other ways.

In the illustrated embodiment of fig. 4, the compressed SSID field 460 may be used for a purpose similar to the SSID field 344 described above with respect to fig. 3. In particular, the compressed SSID field 460 may identify a wireless network. However, although the SSID field 344 includes an alphanumeric string of variable length, the compressed SSID field 460 may be shorter. For example, the compressed SSID field 460 may only include 4 bytes. In one embodiment, the compressed SSID field 460 is a hash of the SSID of the access point, such as, for example, the SSID hash field 430 described above with respect to fig. 4. In one embodiment, the compressed SSID field 460 may be a CRC calculated over a portion, or all, of the SSID associated with the AP 104. For example, the compressed SSID field 460 may use the same generator polynomial that was used to calculate the CRC checksum 490.

In one embodiment, the STA may request the full SSID from the AP transmitting the low overhead beacon frame 400 through a probe request. In another embodiment, a STA searching for a particular SSID may determine whether the AP matches the desired SSID by hashing the desired SSID and comparing the result to the compressed SSID field 460. In one embodiment, the length of the compressed SSID field 460 may be selected such that the chance of two different network SSIDs hashing to the same value is less than 0.5%.

Still referring to fig. 4, the access network options field 470 may include access services provided by the AP 104. For example, the access network option field 470 may include a 4-bit access network type field, a 1-bit internet flag, a 1-bit access required Additional Steps (ASRA) flag, a 1-bit Emergency Services Reachable (ESR) flag, and a 1-bit Unauthenticated Emergency Services Accessible (UESA) flag. The access network options field 470 may help a STA to quickly filter out undesired APs in all scanned channels based on frequently transmitted compressed beacons 400 without wasting time and/or power tracking the full beacon 300 or probe response from each AP.

Still referring to fig. 4, the optional IE field 480 may include additional information elements, as will be described herein. In one embodiment, the optional IE field 480 includes a full TIM or TIM follow indicator. In another embodiment, optional IE field 480 includes additional beacon information.

Still referring to fig. 4, the CRC field 490 may serve a similar purpose as the FCS field 306 described above with respect to fig. 3. In particular, the CRC field 490 may allow the receiving STA to identify transmission errors in the received beacon. Although CRC field 490 is shown as being 4 bytes in length, CRC field 490 may have a different length in various embodiments. For example, in one embodiment, the CRC field 490 is 2 bytes in length. In another embodiment, the CRC field 490 is 1 byte in length. The CRC field 490 may be another type of check code. In one embodiment, the CRC field 490 is a Message Integrity Check (MIC).

In one embodiment, the low overhead beacon frame 400 may be referred to as an "SSID short beacon". The SSID short beacon 400 may be broadcast (e.g., by the AP104 shown in fig. 1) to at least one non-associated STA 106. The SSID short beacon 400 can be used to advertise an SSID (or compressed SSID 430) to non-associated STAs 106 that may be searching for a network. In one embodiment, the AP104 transmits the SSID short beacon 400 at an SSID short beacon interval. The SSID short beacon interval may be a multiple of the beacon interval field of the full beacon ("full beacon interval," such as, for example, the beacon interval field 322 discussed above with respect to fig. 3). For example, the SSID short beacon interval may be one time the full beacon interval, two times the full beacon interval, three times the full beacon interval, and so on.

In one embodiment, the Frame Control (FC) field 410 contains a flag indicating that the beacon frame 400 is a Low Overhead Beacon (LOB), also referred to as a "short beacon," and more specifically, an "SSID short beacon. In one embodiment, the FC field 410 may indicate that the beacon frame 400 is an SSID short beacon by setting a "type value" (which may be bits B3: B2 of the FC field 410) to "11" (which may indicate a beacon frame) and by setting a "subtype value" (which may be bits B7: B4 of the FC field 410) to "0001" (which may indicate that the beacon is compressed, low overhead, "short," and/or targeted for non-associated STAs). When a STA receives a beacon frame 400, it may decode the FC field 410, which contains a flag indicating that the beacon frame 400 is an SSID short beacon. Accordingly, the STA may decode the beacon frame 400 according to the format described herein. As discussed above, a STA receiving the SSID short beacon may not be associated with the AP transmitting the SSID short beacon.

In one embodiment, the access point may periodically send a bitmap (i.e., TIM) within the beacon to identify which stations using the power save mode have data frames waiting for them in the access point's buffer. The TIM identifies the stations by the association id (aid) assigned by the access point during the association process. However, in various low traffic and/or low power network environments, it may not be desirable to periodically send a TIM. For example, in an electronic price label application, the electronic price display may be updated only once per hour. Therefore, it may be wasteful to send a TIM once per TIM interval (which is conventionally much shorter than once per hour). However, in embodiments where the TIM is not sent once per TIM interval, the TIM interval is preferably small so that it can be communicated quickly when an update does occur.

Fig. 5 illustrates another example low overhead beacon frame 500. In the illustrated embodiment, the low overhead beacon frame 500 includes a Frame Control (FC) field 510, a Source Address (SA) field 520, a timestamp 540, a change sequence field 550, a Traffic Indication Map (TIM) Information Element (IE)566, and a Cyclic Redundancy Check (CRC) field 580. As shown, the Frame Control (FC) field 510 is 2 bytes long, the Source Address (SA) field 520 is 6 bytes long, the timestamp 540 is 4 bytes long, the change sequence field 550 is 1 byte long, the TIM IE field 566 is variable length, and the Cyclic Redundancy Check (CRC) field 580 is 4 bytes long. In various embodiments, low overhead beacon frame 500 may omit one or more fields shown in fig. 5 and/or include one or more fields not shown in fig. 5 (including any fields discussed herein). One of ordinary skill in the art will appreciate that the fields in the low overhead beacon frame 500 may be of different suitable lengths and may be in different orders.

In one embodiment, the low overhead beacon frame 500 may be referred to as a "TIM short beacon". The TIM short beacon 500 may be broadcast (e.g., by the AP104 shown in fig. 1) to at least one associated STA 106. The TIM short beacon 500 may be used to provide a timestamp for the STA to maintain synchronization and/or to provide a sequence of changes to indicate when network information has changed. In one embodiment, the AP104 transmits the TIM short beacon 500 in a TIM short beacon interval. The TIM short beacon interval may be a multiple of the beacon interval field of the full beacon ("full beacon interval", such as, for example, the beacon interval field 322 discussed above with respect to fig. 3). For example, the TIM short beacon interval may be one time the full beacon interval, two times the full beacon interval, three times the full beacon interval, and so on.

In one embodiment, the TIM short beacon interval may be different from the SSID short beacon interval discussed above with respect to fig. 4. In one embodiment, the AP104 may be configured to transmit one or more of the SSID short beacon 400, the TIM short beacon 500, and the full beacon at a Target Beacon Transmit Time (TBTT) according to an SSID short beacon interval, a TIM short beacon interval, and a full beacon interval, respectively. In one embodiment, when the AP104 transmits both the SSID short beacon 400 and the TIM short beacon 500, the AP104 transmits the TIM short beacon 500 first, followed by the SSID short beacon 400 for SIFS time.

The Destination Address (DA) field 312 described above with respect to fig. 3 may be omitted from the low-overhead beacon frame 500 because the beacon frame 500 may be broadcast. Thus, there is no need to identify a specific destination address. Similarly, BSSID field 316 may be omitted. The duration field 310 may be omitted. In one embodiment, if a Network Allocation Vector (NAV) is desired after the transmission of the low-overhead beacon frame 500, the NAV may be signaled using a short interframe space (SIFS) after the beacon frame 500 is transmitted. Further, the sequence control field 318 may be omitted from the low overhead beacon frame 500 because sequence control may not be necessary in the beacon.

In one embodiment, the Frame Control (FC) field 510 contains a flag indicating that the beacon frame 500 is a Low Overhead Beacon (LOB), also referred to as a "short beacon," and more specifically, a "TIM short beacon. In one embodiment, the FC field 510 may indicate that the beacon frame 500 is a TIM short beacon by setting the "type value" (which may be bits B3: B2 of the FC field 510) to "11" (which may indicate a beacon frame) and by setting the "subtype value" (which may be bits B7: B4 of the FC field 510) to "0010" (which may indicate that the beacon is compressed, low overhead, "short," and/or targeted to an associated STA). When a STA receives a beacon frame 500, it may decode the FC field 510 containing a flag indicating that the beacon frame 500 is a TIM short beacon. Accordingly, the STA may decode the beacon frame 500 according to the format described herein. As discussed above, a STA receiving a TIM short beacon may associate with an AP transmitting the TIM short beacon.

In the illustrated embodiment of fig. 5, timestamp field 540 is shorter than timestamp field 320 described above with respect to fig. 3. Specifically, timestamp field 540 is only 4 bytes in length, while timestamp field 320 is 8 bytes in length. In one embodiment, a STA receiving a low overhead beacon 500 may retrieve a full eight byte timestamp from the transmitting AP via a probe request. In one embodiment, the length of timestamp field 540 may be selected such that timestamp field 540 will not overflow more than once every seven minutes. In conventional systems, the timestamp field 320 value is interpreted as nanoseconds. In one embodiment, the timestamp field 540 value may be interpreted as a number of OFDM symbol periods. Accordingly, in embodiments where the OFDM symbol period is longer than one nanosecond, the timestamp field 540 may overflow less quickly.

In one embodiment, the timestamp field 540 may facilitate a Timing Synchronization Function (TSF) between the devices 104 and 106 in the wireless communication system 100. In an embodiment where AP104 updates timestamp field 540 at 1MHz, a 4 byte timestamp field 540 would overflow approximately every 72 minutes. In an embodiment where the device clock is driven at about +/-20ppm, driving for 30 minutes takes about 1.4 years. Thus, the device 106 may maintain time synchronization with the AP104 if it checks the beacon 500 as little as once per day.

In the illustrated embodiment of fig. 5, change sequence field 550 may be used to provide a sequence number indicating a change in network information. In the illustrated embodiment, change sequence field 550 is used to track changes to AP 104. In one embodiment, AP104 may increment change sequence field 550 when one or more parameters of AP104 change. For example, the AP may transmit a full beacon when the SSID changes. In one embodiment, when the configuration of AP104 changes, AP104 may decrement change sequence field 550, change sequence field 550 to a random or pseudo-random number, or otherwise modify change sequence field 550. In various embodiments, change sequence field 550 may be referred to as a beacon index or beacon number.

STA106 may be configured to detect a change in change sequence field 550. When the STA106 detects a change in the change sequence field 550, the STA106 may wait for transmission of a full beacon. When the STA106 waits for the AP104 to transmit a full beacon, it may defer transitioning to the sleep or low power mode. In another embodiment, when the STA106 detects a change in the change sequence field 550, the STA106 may send a probe request frame to the AP 104. The AP104 may send the updated configuration information to the STA106 in response to the probe request frame.

Still referring to fig. 5, the TIM IE field 566 is used to identify which stations using the power save mode have data frames waiting for them in the access point's buffer. In one embodiment, the TIM IE field 566 may be a bitmap. The TIM IE field 566 can identify a station by an association id (aid) assigned by an access point during an association process.

Still referring to fig. 5, the CRC field 580 may serve a similar purpose as the FCS field 306 described above with respect to fig. 3. In particular, the CRC field 580 may allow the receiving STA to identify transmission errors in the received beacon. Although CRC field 580 is shown as being 4 bytes in length, CRC field 580 may have a different length in various embodiments. For example, in one embodiment, the CRC field 580 is 2 bytes in length. In another embodiment, the CRC field 580 is 1 byte in length. The CRC field 580 may be another type of check code. In one embodiment, the CRC field 580 is a Message Integrity Check (MIC).

Fig. 6 is a timing diagram 600 illustrating exemplary beacon timing. As discussed herein, an AP104 may be configured to transmit "full beacons" and/or one or more "short beacons" at various intervals. In one embodiment, the AP104 may transmit short beacons 620 and 630 at each beacon interval 610. In various embodiments, the short beacons 620 and 630 may include, for example, one or more of the low overhead beacon frame 400 (fig. 4) and the TIM short beacon 500 (fig. 5). For example, beacon interval 610 can be communicated in beacon interval field 322 (fig. 3). For example, in one embodiment, the beacon interval 610 may be 100 TUs or 102400 μ s.

Still referring to fig. 6, in the illustrated embodiment, the AP104 transmits the short beacons 620 and 630 only during the beacon intervals in which it does not transmit the full beacon 640. The AP104 may transmit a full beacon 640 during the full beacon interval 650. In one embodiment, full beacon 640 may comprise, for example, full beacon 300 (fig. 3). Full beacon interval 650 may be a first multiple of beacon interval 610. For example, in the illustrated embodiment, full beacon interval 650 is six times the beacon interval 610. In various embodiments, full beacon interval 650 may be equal to beacon interval 610, twice beacon interval 610, three times beacon interval 610, and so on.

Still referring to fig. 6, in the illustrated embodiment, the AP104 may include a Traffic Indication Map (TIM) element in each beacon transmitted with a TIM period 660. The TIM period 660 may be a second multiple of the beacon interval 610. For example, in the illustrated embodiment, the TIM period 660 is twice the beacon interval 610. In various embodiments, the TIM period 660 may be equal to the beacon interval 610, three times the beacon interval 610, four times the beacon interval 610, and so on. As shown, the AP104 includes the TIM in the full beacon 640 and the short beacon 630 according to a TIM period 660 of two beacon intervals 610. Similarly, in various embodiments, the AP104 may include a Delivery Traffic Indication Map (DTIM) element in each beacon transmitted with a DTIM period (not shown).

In one embodiment, the AP may not transmit the TIM short beacon 630. Instead, all short beacons 620 and 630 may be SSID short beacons 620. For example, short beacons 620 and 630 may both be low overhead beacons 400 (fig. 4).

Fig. 7 illustrates a flow diagram 700 of an example method for generating a compressed (or low overhead) beacon. The method of flowchart 700 may be used to create a low overhead beacon, such as, for example, low overhead beacon 400 described above with respect to fig. 4. The compressed beacon may be generated at the AP104 (fig. 1) and transmitted to another node in the wireless communication system 100. Although the method is described below with respect to elements of the wireless device 202a (fig. 2), persons of ordinary skill in the art will appreciate that the method of flow chart 700 may be implemented by any other suitable device. In one embodiment, the steps in flowchart 700 may be performed by processor 204 in conjunction with transmitter 210 and memory 206. Although the method of flowchart 700 is described herein with reference to a particular order, in various embodiments, the blocks herein may be performed in a different order, or omitted, and additional blocks may be added.

First, at block 710, the wireless device 202a creates a shortened network identifier. The shortened network identifier may be shorter than the full network identifier. For example, the shortened network identifier may be a compressed SSID 460 (fig. 4), and the full network identifier may be an SSID 326 (fig. 3). In one embodiment, the processor 204 creates a 1-byte SSID hash from the SSID of the AP 104. In another embodiment, the processor 204 may calculate a 4-byte Cyclic Redundancy Check (CRC) for the full network identifier. Processor 204 may use the same generator polynomial that was used to calculate CRC 490. In various other embodiments, the processor 204 may shorten the SSID in another manner (such as, for example, truncation, cryptographic hashing, etc.). In another embodiment, the wireless device 202a may create a shortened identifier from an identifier that is different from the SSID. For example, in one embodiment, wireless device 202a may shorten the BSSID. For example, the creation of the SSID hash may be performed by the processor 204 and/or the DSP 220.

Next, at block 720, the wireless device 202a generates a compressed beacon. The compressed beacon may include a SSID hash or another shortened identifier as discussed above with respect to block 710. In one embodiment, wireless device 202a may generate a compressed beacon according to compressed beacon frame 400 discussed above with respect to fig. 4. For example, this generation may be performed by the processor 204 and/or the DSP 220.

Thereafter, at block 730, the wireless device 202a wirelessly transmits the compressed beacon. The transmission may be performed, for example, by the transmitter 210.

Fig. 8 is a functional block diagram of an exemplary wireless device 800 that may be employed within the wireless communication system 100 of fig. 1. Those skilled in the art will appreciate that the wireless device 800 may have more components than the simplified wireless device 800 shown in fig. 8. The illustrated wireless device 800 includes only those components useful for describing some prominent features of implementations within the scope of the claims. Apparatus 800 includes means 810 for creating a shortened network identifier, means 820 for generating a compressed beacon including the shortened network identifier, and means 830 for transmitting the compressed beacon.

The means for creating a shortened network identifier 810 may be configured to perform one or more of the functions discussed above with respect to block 710 illustrated in fig. 7. The means for creating a shortened network identifier 810 may correspond to one or more of the processor 204 and the DSP220 (fig. 2). The means 820 for generating a compressed beacon including the shortened network identifier may be configured to perform one or more of the functions discussed above with respect to block 720 illustrated in fig. 7. The means 820 for generating a compressed beacon including the shortened network identifier may correspond to one or more of the processor 204 and the DSP 220. The means for transmitting the compressed beacon 830 may be configured to perform one or more of the functions discussed above with respect to block 730 illustrated in fig. 7. The means for transmitting 830 the compressed beacon may correspond to the transmitter 210.

Fig. 9 illustrates a flow diagram 900 of an example method for processing compressed (or low overhead) beacons. The method of flowchart 900 may be used to process low overhead beacons, such as, for example, low overhead beacon 400 described above with respect to fig. 4. The compressed beacon may be processed at the STA106 (fig. 1) and received from another node in the wireless communication network 100. Although the method is described below with respect to elements of the wireless device 202s (fig. 2), persons of ordinary skill in the art will appreciate that the method of flowchart 900 may be implemented by any other suitable device. In one embodiment, the steps of flowchart 900 may be performed by processor 204 in conjunction with receiver 212 and memory 206. Although the method of flowchart 900 is described herein with reference to a particular order, in various embodiments, the blocks herein may be performed in a different order, or omitted, and additional blocks may be added.

First, at block 910, the wireless device 202s receives a compressed beacon including a shortened network identifier. The shortened network identifier may be shorter than the full network identifier. For example, the shortened network identifier may be a compressed SSID 460 (fig. 4), and the full network identifier may be an SSID 326 (fig. 3). The device 202s may be associated with a network having a network identifier. For example, the device 202s may associate with the communication system 100 via the AP104 with the SSID. For example, the compressed beacon may be received via the receiver 212.

Next, at block 920, the wireless device 202s creates an expected shortened network identifier based on the network identifier of the network associated with the device 202 s. For example, the processor 204 may compute and create a 1-byte SSID hash from the SSID of the AP 104. In another embodiment, the processor 204 may calculate a 4-byte Cyclic Redundancy Check (CRC) for the full network identifier. Processor 204 may use the same generator polynomial that was used to calculate CRC 490. In various other embodiments, the processor 204 may shorten the SSID in another manner (such as, for example, truncation, cryptographic hashing, etc.). In another embodiment, the wireless device 202s may create the expected shortened identifier from an identifier that is different from the SSID. For example, in one embodiment, the wireless device 202s may shorten the BSSID. For example, the creation of the intended shortened network identifier may be performed by the processor 204 and/or the DSP 220.

The wireless device 202s then compares the expected shortened network identifier generated using the SSID of the associated AP104 with the received shortened network identifier at block 930. For example, this comparison may be performed by the processor 204 and/or the DSP 220.

Then, at block 940, the wireless device 202s discards the received compressed beacon when the received shortened network identifier does not match the expected shortened network identifier. The mismatch may indicate that the received compressed beacon is not from an associated AP. For example, the compressed beacon may be discarded by the processor 204 and/or the DSP 220.

The wireless device 202s then processes the compressed beacon at block 950 when the received shortened network identifier matches the expected shortened network identifier. The match may indicate that the received compressed beacon is from an associated AP. For example, the compressed beacon may be processed by the processor 204 and/or the DSP 220.

Fig. 10 is a functional block diagram of another exemplary wireless device 1000 that may be employed within the wireless communication system 100 of fig. 1. Those skilled in the art will appreciate that the wireless device 1000 may have more components than the simplified wireless device 1000 shown in fig. 10. The illustrated wireless device 1000 includes only those components useful for describing some prominent features of implementations within the scope of the claims. The device 1000 includes means 1010 for receiving a compressed beacon including a shortened network identifier at a device associated with a network having a network identifier, means 1020 for creating an expected shortened network identifier based on the network identifier of the network associated with the device, means 1030 for comparing the expected shortened network identifier to the received shortened network identifier, means 1040 for discarding the compressed beacon when the expected shortened network identifier does not match the received shortened network identifier, and means 1050 for processing the compressed beacon when the expected shortened network identifier matches the received shortened network identifier.

The means 1010 for receiving, at a device associated with a network having a network identifier, a compressed beacon including a shortened network identifier may be configured to perform one or more functions discussed above with respect to block 910 illustrated in fig. 9. Means 1010 for receiving, at an apparatus associated with a network having a network identifier, a compressed beacon comprising a shortened network identifier may correspond to one or more of receiver 212 and memory 206 (fig. 2).

The means 1020 for creating the expected shortened network identifier based on the network identifier of the network associated with the device may be configured to perform one or more of the functions discussed above with respect to block 920 illustrated in fig. 9. The means 1020 for creating the expected shortened network identifier based on the network identifier of the network associated with the apparatus may correspond to one or more of the processor 204 and the DSP 220.

The means 1030 for comparing the expected shortened network identifier with the received shortened network identifier may be configured to perform one or more of the functions discussed above with respect to block 930 illustrated in fig. 9. The means 1030 for comparing the expected shortened network identifier with the received shortened network identifier may correspond to one or more of the processor 204 and the DSP 220.

The means 1040 for discarding the compressed beacon when the expected shortened network identifier does not match the received shortened network identifier may be configured to perform one or more of the functions discussed above with respect to block 940 illustrated in fig. 9. The means 1040 for discarding the compressed beacon when the expected shortened network identifier does not match the received shortened network identifier may correspond to one or more of the processor 204 and the DSP 220.

The means 1050 for processing the compressed beacon when the expected shortened network identifier matches the received shortened network identifier may be configured to perform one or more of the functions discussed above with respect to block 950 illustrated in fig. 9. Means 1050 for processing the compressed beacon when the expected shortened network identifier matches the received shortened network identifier may correspond to one or more of the processor 204 and the DSP 220.

Fig. 11 illustrates a flow diagram 1100 of another exemplary method for generating a compressed (or low overhead) beacon. The method of flowchart 1100 may be used to create a low-overhead beacon, such as, for example, low-overhead beacon 400 described above with respect to fig. 4. The compressed beacon may be generated at the AP104 (fig. 1) and transmitted to another node in the wireless communication network 100. Although the method is described below with respect to elements of the wireless device 202a (fig. 2), persons of ordinary skill in the art will appreciate that the method of flowchart 1100 may be implemented by any other suitable device. In one embodiment, the steps in flowchart 1100 may be performed by processor 204 in conjunction with transmitter 210 and memory 206. Although the method of flowchart 1100 is described herein with reference to a particular order, in various embodiments, the blocks herein may be performed in a different order, or omitted, and additional blocks may be added.

First, at block 1110, the wireless device 202a generates a compressed beacon including a next full beacon time indication. In one embodiment, the next full beacon time indication may be the next full beacon time indication field 450 described above with respect to fig. 4. Wireless device 202a may determine the next time it will transmit a full beacon, such as beacon 300 (fig. 3). This time may be referred to as the next Target Beacon Transmit Time (TBTT). In one embodiment, the next full beacon time indication may include the time at which the access point will transmit a full beacon. The next full beacon time indication may be the 3 most significant bytes of the 4 least significant bytes of the next Target Beacon Transmit Time (TBTT).

In another embodiment, the next full beacon time indication may include a flag indicating that wireless device 202a is to transmit a full beacon including one or more fields not included in the compressed beacon. The flag may indicate that the next beacon transmitted will be a full beacon. In another embodiment, the next full beacon time indication may comprise a value indicating a duration until the wireless device 202a transmits the next full beacon. The next full beacon time indication may indicate the number of Time Units (TUs) until the access point transmits the next full beacon. For example, the compressed beacon and the next full beacon time indication may be generated by the processor 204 and/or the DSP 220.

Next, at block 1120, the wireless device 202a wirelessly transmits the compressed beacon. The transmission may be performed, for example, by the transmitter 210. Thereafter, at the next TBTT, the wireless device 202a may generate and transmit a full beacon and transmit.

Fig. 12 is a functional block diagram of another exemplary wireless device 1200 that may be employed within the wireless communication system 100 of fig. 1. Those skilled in the art will appreciate that the wireless device 1200 may have more components than the simplified wireless device 1200 shown in fig. 12. The illustrated wireless device 1200 includes only those components useful for describing some prominent features of implementations within the scope of the claims. Apparatus 1200 includes means 1210 for generating a compressed beacon including a next full beacon time indication, and means 1220 for transmitting the compressed beacon.

The means 1210 for generating a compressed beacon including the next full beacon time indication may be configured to perform one or more of the functions discussed above with respect to block 1110 illustrated in fig. 11. The means 1210 for generating a compressed beacon including the next full beacon time indication may correspond to one or more of the processor 204 and the DSP220 (fig. 2). The means for transmitting the compressed beacon 1220 may be configured to perform one or more of the functions discussed above with respect to block 1120 illustrated in fig. 11. The means for transmitting the compressed beacon 1220 may correspond to the transmitter 210.

Fig. 13 shows a flow diagram 1300 of an exemplary method for operating the wireless device 202s of fig. 2. Although the method is described below with respect to elements of the wireless device 202s (fig. 2), persons of ordinary skill in the art will appreciate that the method of flowchart 1300 may be implemented by any other suitable device. In one embodiment, the steps of flowchart 1300 may be performed by processor 204 in conjunction with receiver 212, power supply 230, and memory 206. Although the method of flowchart 1300 is described herein with reference to a particular order, in various embodiments, the blocks herein may be performed in a different order, or omitted, and additional blocks may be added.

First, at block 1310, the wireless device 202s receives a compressed beacon including a Next Full Beacon Time Indication (NFBTI). The compressed beacon may be, for example, the low overhead beacon 400 described above with respect to fig. 4. The compressed beacon may be generated at the AP104 (fig. 1) and transmitted to the STA106 via the wireless communication system 100. For example, the wireless device 202s may use the receiver 212 to receive the compressed beacon.

In one embodiment, the next full beacon time indication may be the next full beacon time indication field 450 described above with respect to fig. 4. As discussed above, wireless device 202a may determine the next time it will transmit a full beacon, such as beacon 300 (fig. 3). This time may be referred to as the next Target Beacon Transmit Time (TBTT). In one embodiment, the next full beacon time indication may include the time at which the access point will transmit a full beacon. The next full beacon time indication may be the 3 most significant bytes of the 4 least significant bytes of the next Target Beacon Transmit Time (TBTT).

In another embodiment, the next full beacon time indication may include a flag indicating that wireless device 202a is to transmit a full beacon including one or more fields not included in the compressed beacon. The flag may indicate that the next beacon transmitted will be a full beacon. In another embodiment, the next full beacon time indication may comprise a value indicating a duration until the wireless device 202a transmits the next full beacon. The next full beacon time indication may indicate the number of Time Units (TUs) until the access point transmits the next full beacon.

Next, at block 1320, the wireless device 202s may operate in the first power mode for a duration based on the next full beacon time indication. For example, the wireless device 202s may enter a low power state until shortly before the next full beacon will be transmitted in order to conserve power. For example, the wireless device 202s may shut down one or more components (such as the processor 204, the transmitter 210, and/or the receiver 212), or place the one or more components in a low power mode.

The wireless device 202s may determine the next time at which the AP104 will transmit a full beacon based on the next full beacon time indication received in the compressed beacon. The processor 204 may set a timer to wake up at least a first time before a next full beacon is expected. The wireless device 202s may operate in a first power mode in conjunction with other components via the power supply 230.

Then, at block 1330, the wireless device 202s transitions to the second lower power mode at the end of the duration. For example, upon expiration of the timer, the wireless device 204 may wake up from the low power mode and activate or enter one or more of the processor 204, the transmitter 210, and the receiver 212 into a higher power mode. The wireless device 202s may transition to the second power mode through the power supply 230 in conjunction with other components. Subsequently, the wireless device 202s can receive the full beacon from the AP 104.

Fig. 14 is a functional block diagram of another exemplary wireless device 1400 that may be employed within the wireless communication system 100 of fig. 1. Those skilled in the art will appreciate that the wireless device 1400 may have more components than the simplified wireless device 1400 shown in fig. 14. The illustrated wireless device 1400 includes only those components useful for describing some prominent features of implementations within the scope of the claims. The device 1400 includes means 1410 for receiving a compressed beacon including a Next Full Beacon Time Indication (NFBTI), means 1420 for operating the wireless device in a first power mode for a duration based on the next full beacon time indication, means 1430 for transitioning the wireless device to a second higher power mode at an end of the duration.

The means 1410 for receiving a compressed beacon including a next full beacon time indication may be configured to perform one or more functions discussed above with respect to block 1310 illustrated in fig. 13. The means 1410 for receiving a compressed beacon including the next full beacon time indication may correspond to one or more of the processor 204 and the receiver 212 (fig. 2). The means 1420 for operating the wireless device in the first power mode for a duration based on the next full beacon time indication may be configured to perform one or more functions discussed above with respect to block 1320 illustrated in fig. 13. Means 1420 for operating the wireless device in the first power mode for a duration based on the next full beacon time indication may correspond to one or more of the processor 204 and the power supply 230. Means 1430 for transitioning the wireless device to the second higher power mode at the end of the duration may be configured to perform one or more functions discussed above with respect to block 1330 illustrated in fig. 13. Means 1430 for transitioning the wireless device to a second higher power mode at the end of the duration may correspond to one or more of the processor 204 and the power supply 230.

Fig. 15 shows a flowchart 1500 of an exemplary method for communicating in the wireless communication system 100 of fig. 1. The method of flowchart 1500 may be used to create and transmit a low overhead beacon, such as, for example, low overhead beacon 400 described above with respect to fig. 4. The compressed beacon may be generated at the AP104 (fig. 1) and transmitted to another node in the wireless communication system 100. Although the method is described below with respect to elements of wireless device 202a (fig. 2), persons of ordinary skill in the art will appreciate that the method of flowchart 1500 may be implemented by any other suitable device. In one embodiment, the steps in flowchart 1500 may be performed by processor 204 in conjunction with transmitter 210 and memory 206. Although the method of flowchart 1500 is described herein with reference to a particular order, in various embodiments, the blocks herein may be performed in a different order, or omitted, and additional blocks may be added.

First, at block 1510, the wireless device 202a transmits a full beacon at a first multiple of a beacon interval. In one embodiment, the full beacon may be the beacon 300 described above with respect to fig. 3. In various embodiments, the first multiple may be 2, 3, 4, 5, etc. The wireless device 202a may communicate the beacon interval and/or the first multiple to the STA106 via a field in the full beacon in response to the probe request, or the beacon interval and/or the first multiple may be preset. For example, wireless device 202a may generate a full beacon using processor 204 and may transmit the full beacon via transmitter 210.

Next, at block 1520, the wireless device 202a transmits a compressed beacon at each beacon interval that is not the first multiple of the beacon interval at block 1510. The compressed beacon may be, for example, beacon 400 (fig. 4). In one embodiment, wireless device 202a may transmit a compressed beacon at a second multiple of the beacon interval, except where the second multiple happens to coincide with the first multiple. For example, wireless device 202a may generate a compressed beacon using processor 204 and may transmit the compressed beacon via transmitter 210.

Fig. 16 is a functional block diagram of another exemplary wireless device 1600 that may be employed within the wireless communication system 100 of fig. 1. Those skilled in the art will appreciate that the wireless device 1600 may have more components than the simplified wireless device 1600 shown in fig. 16. The illustrated wireless device 1600 includes only those components useful for describing some prominent features of implementations within the scope of the claims. Apparatus 1600 includes means 1610 for transmitting a full beacon at a first multiple of a beacon interval, and means 1620 for transmitting a compressed beacon at each beacon interval that is not the first multiple of the beacon interval.

The means for transmitting a full beacon at a first multiple of the beacon interval 1610 may be configured to perform one or more functions discussed above with respect to block 1510 illustrated in fig. 15. The means for transmitting a full beacon at a first multiple of the beacon interval 1610 may correspond to one or more of the processor 204 and the transmitter 210 (fig. 2). Means 1620 for transmitting a compressed beacon at each beacon interval that is not the first multiple of the beacon interval may be configured to perform one or more functions discussed above with respect to block 1520 illustrated in fig. 15. Means 1620 for transmitting a compressed beacon at each beacon interval that is not the first multiple of the beacon interval may correspond to one or more of processor 204 and transmitter 210 (fig. 2).

Fig. 17 illustrates a flow diagram 1700 of another example method for communicating in the wireless communication system 100 of fig. 1. The method of flowchart 1700 may be used to receive a low overhead beacon, such as, for example, low overhead beacon 400 described above with respect to fig. 4. The compressed beacon may be generated at the AP104 (fig. 1) and transmitted to the STAs 106 in the wireless communication system 100. Although the method is described below with respect to elements of the wireless device 202s (fig. 2), persons of ordinary skill in the art will appreciate that the method of flowchart 1700 may be implemented by any other suitable device. In one embodiment, the steps of flowchart 1700 may be performed by processor 204 in conjunction with transmitter 210 and memory 206. Although the method of flowchart 1700 is described herein with reference to a particular order, in various embodiments, the blocks herein may be performed in a different order, or omitted, and additional blocks may be added.

First, at block 1710, the wireless device 202s receives a full beacon at a first multiple of a beacon interval. In one embodiment, the full beacon may be the beacon 300 described above with respect to fig. 3. In various embodiments, the first multiple may be 2, 3, 4, 5, etc. The wireless device 202s can receive the beacon interval and/or the first multiple from the AP104 via a field in the full beacon in response to the probe request, or the beacon interval and/or the first multiple can be preset. For example, the wireless device 202s may receive the full beacon via the receiver 212.

Next, at block 1720, the wireless device 202s receives a compressed beacon at a beacon interval that is not the first multiple of the beacon interval at block 1710. The compressed beacon may be, for example, beacon 400 (fig. 4). In one embodiment, the wireless device 202s may receive the compressed beacon at a second multiple of the beacon interval, except where the second multiple happens to coincide with the first multiple. For example, the wireless device 202s may receive via the receiver 212.

Fig. 18 is a functional block diagram of another exemplary wireless device 1800 that may be employed within the wireless communication system 100 of fig. 1. Those skilled in the art will appreciate that the wireless device 1800 may have more components than the simplified wireless device 1800 shown in fig. 18. The illustrated wireless device 1800 includes only those components useful for describing some prominent features of implementations within the scope of the claims. Apparatus 1800 includes means 1810 for receiving a full beacon at a first multiple of a beacon interval, and means 1820 for receiving a compressed beacon at a beacon interval that is not the first multiple of the beacon interval.

The means 1810 for receiving the full beacon at the first multiple of a beacon interval may be configured to perform one or more functions discussed above with respect to block 1710 illustrated in fig. 17. The means 1810 for receiving a full beacon at a first multiple of a beacon interval may correspond to one or more of the processor 204 and the receiver 212 (fig. 2). The means 1820 for receiving the compressed beacon at a beacon interval that is not the first multiple of the beacon interval may be configured to perform one or more functions discussed above with respect to block 1720 illustrated in fig. 17. Means 1820 for receiving a compressed beacon at each beacon interval that is not the first multiple of the beacon interval may correspond to one or more of the processor 204 and the receiver 212 (fig. 2).

Several embodiments described above include a compressed SSID field (e.g., 460). In some implementations, the compressed SSID field may be selectively generated. In some implementations, the selection may be based on the length of the full SSID of the signal. For example, if the length of the full SSID (e.g., 4 bytes) is equal to the length of the compressed SSID field (e.g., 4 bytes), the full SSID may be used as the compressed SSID. In some implementations, if the length of the full SSID is longer than the length of the compressed SSID field, a CRC computed over a portion or all of the full SSID may be used as the compressed SSID. The calculated CRC may have a length equal to the length of the compressed SSID field. In some implementations, if the length of the full SSID is less than the length of the compressed SSID field, the full SSID may be increased in length (e.g., padded) to equal the length of the compressed SSID field to form the compressed SSID. For example, if the compressed SSID field is 8 bytes and the full SSID is 4 bytes, then a 4-byte pad may be added to the full SSID to generate an 8-byte compressed SSID. The population may include before the full SSID (e.g., at the beginning) or after the full SSID (e.g., at the end). The padding may include null characters, padding characters (e.g., alphanumeric, non-alphanumeric), or a combination thereof.

As used herein, the term "determining" broadly encompasses a wide variety of actions. For example, "determining" can include calculating, computing, processing, deriving, studying, looking up (e.g., looking up in a table, database, or other data structure), ascertaining, and the like. Also, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. Also, "determining" may include resolving, selecting, choosing, establishing, and the like. In addition, "channel width" as used herein may encompass in some aspects or may also be referred to as bandwidth.

As used herein, a phrase referring to "at least one of a list of items refers to any combination of those items, including a single member. By way of example, "at least one of a, b, or c" is intended to encompass: a. b, c, a-b, a-c, b-c, and a-b-c.

The various operations of the methods described above may be performed by any suitable means capable of performing the operations, such as various hardware and/or software components, circuits, and/or modules. In general, any of the operations illustrated in the figures may be performed by corresponding functional means capable of performing the operations.

The various illustrative logical blocks, modules, and circuits described in connection with the disclosure may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a field programmable gate array signal (FPGA) or other Programmable Logic Device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

In one or more aspects, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a web site, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk (disk) and disc (disc), as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks (disks) usually reproduce data magnetically, while discs (discs) reproduce data optically with lasers. Thus, in some aspects, computer-readable media may comprise non-transitory computer-readable media (e.g., tangible media). Additionally, in some aspects, the computer readable medium may comprise a transitory computer readable medium (e.g., a signal). Combinations of the above should also be included within the scope of computer-readable media.

The methods disclosed herein comprise one or more steps or actions for achieving the described method. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.

The functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions on a computer-readable medium. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Disk (disk) and disc (disc), as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk, anddisks, where a disk (disk) usually reproduces data magnetically, and a disk (disc) reproduces data optically with a laser.

Thus, certain aspects may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may include a computer-readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein. For certain aspects, the computer program product may include packaging materials.

The software or instructions may also be transmitted over a transmission medium. For example, if the software is transmitted from a web site, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of transmission medium.

Further, it is to be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station where applicable. For example, such a device can be coupled to a server to facilitate the transfer of an apparatus for performing the methods described herein. Alternatively, the various methods described herein can be provided via a storage device (e.g., RAM, ROM, a physical storage medium such as a Compact Disc (CD) or floppy disk, etc.), such that the apparatus can obtain the various methods upon coupling or providing the storage device to a user terminal and/or base station. Further, any other suitable technique suitable for providing the methods and techniques described herein to a device can be utilized.

It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various changes, substitutions and alterations in the arrangement, operation and details of the method and apparatus described above may be made without departing from the scope of the claims.

While the foregoing is directed to aspects of the present disclosure, other and further aspects of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims (96)

1. A method of communicating in a wireless network, comprising:

generating, at an access point, a compressed beacon comprising:

a next full beacon time indication field that indicates, at least in part, timing of a full beacon that includes one or more fields not included in the compressed beacon; and

a frame control field comprising a next full beacon time indication present field, wherein the next full beacon time indication present field identifies whether the compressed beacon comprises the next full beacon time indication field; and

transmitting the compressed beacon at the access point.

2. The method of claim 1, wherein the next full beacon time indication field comprises a time at which the access point will transmit the full beacon.

3. The method of claim 2, wherein the next full beacon time indication field comprises 3 most significant bytes of 4 least significant bytes of a next Target Beacon Transmit Time (TBTT).

4. The method of claim 1, wherein the next full beacon time indication field comprises a flag indicating that the access point will transmit the full beacon.

5. The method of claim 4, further comprising:

generating the full beacon; and

transmitting the full beacon.

6. The method of claim 1, wherein the next full beacon time indication field comprises a value indicating a duration until the access point transmits a next full beacon.

7. The method of claim 6, wherein the next full beacon time indication field indicates a number of Time Units (TUs) until the access point transmits the next full beacon.

8. The method of claim 7, wherein the next full beacon time indication field comprises a null value when the number of beacon intervals to the next full beacon is not determined.

9. The method of claim 1, wherein the compressed beacon comprises:

the frame control field;

a source address;

a time stamp;

altering the sequence;

the next full beacon time indication field; and

and (5) checking the frame.

10. The method of claim 9, wherein the frame control field comprises 2 bytes, the source address comprises 6 bytes, the timestamp comprises 4 bytes, the change sequence comprises 1 byte, the next full beacon time indication field comprises 3 bytes, and the frame check comprises 4 bytes.

11. The method of claim 9, wherein the source address comprises a Basic Service Set Identification (BSSID) of the access point.

12. The method of claim 9, wherein the timestamp comprises one or more least significant bits of a full timestamp.

13. The method of claim 9, wherein the method further comprises: the change sequence is changed when the access point or network configuration changes or when there is a significant change in the content of the full beacon.

14. The method of claim 9, wherein the frame control field comprises a version field, a type field, a subtype field, the next full beacon time indication present field, a Service Set Identifier (SSID) present field, an internetworking present field, a bandwidth field, a security field, and one or more reserved bits.

15. The method of claim 14, wherein the version field comprises 2 bits, the type field comprises 2 bits, the subtype field comprises 4 bits, the next full beacon time indication present field comprises 1 bit, the SSID present field comprises 1 bit, the internetworking present field comprises 1 bit, the bandwidth field comprises 3 bits, the security field comprises 1 bit, and the one or more reserved bits comprise 1 bit.

16. The method of claim 14, wherein a type field comprises a value of "11" and a subtype field comprises a value of "0001" to indicate that a beacon is a compressed beacon.

17. A method of communicating in a wireless network, comprising:

receiving, at a wireless device, a compressed beacon comprising:

a next full beacon time indication field; and

a frame control field comprising a next full beacon time indication present field, wherein the next full beacon time indication present field identifies whether the compressed beacon comprises the next full beacon time indication field; and

operating the wireless device in a first power mode for a duration based on the next full beacon time indication field; and

transitioning the wireless device to a second power mode at the end of the duration,

wherein the wireless device consumes a first power when in the first power mode and a second power when in the second power mode, the first power being lower than the second power.

18. The method of claim 17, wherein the next full beacon time indication field comprises a time at which an access point will transmit a full beacon comprising one or more fields not included in the compressed beacon.

19. The method of claim 18, wherein the next full beacon time indication field comprises the 3 most significant bytes of the 4 least significant bytes of a next Target Beacon Transmit Time (TBTT).

20. The method of claim 17, wherein the next full beacon time indication field comprises a flag indicating that an access point will transmit a full beacon comprising one or more fields not included in the compressed beacon.

21. The method of claim 20, further comprising receiving the full beacon after transitioning the wireless device to the second power mode.

22. The method of claim 17, wherein the next full beacon time indication field comprises a value indicating a duration until an access point transmits a next full beacon.

23. The method of claim 22, wherein the next full beacon time indication field indicates a number of Time Units (TUs) until the access point transmits the next full beacon.

24. The method of claim 23, wherein the next full beacon time indication field comprises a null value when the number of beacon intervals to the next full beacon is not determined.

25. The method of claim 17, wherein the compressed beacon comprises:

the frame control field;

a source address;

a time stamp;

altering the sequence;

the next full beacon time indication field; and

and (5) checking the frame.

26. The method of claim 25, wherein the frame control field comprises 2 bytes, the source address comprises 6 bytes, the timestamp comprises 4 bytes, the change sequence comprises 1 byte, the next full beacon time indication field comprises 3 bytes, and the frame check comprises 4 bytes.

27. The method of claim 25, wherein the source address comprises a Basic Service Set Identification (BSSID) of the access point.

28. The method of claim 25, wherein the timestamp comprises one or more least significant bits of a full timestamp.

29. The method of claim 25, wherein the method further comprises:

detecting a change in the altered sequence;

transmitting a probe request when a change in the change sequence is detected; and

receiving a probe response in response to the probe request.

30. The method of claim 25, wherein the frame control field comprises a version field, a type field, a subtype field, the next full beacon time indication present field, a Service Set Identifier (SSID) present field, an internetworking present field, a bandwidth field, a security field, and one or more reserved bits.

31. The method of claim 30, wherein the version field comprises 2 bits, the type field comprises 2 bits, the subtype field comprises 4 bits, the next full beacon time indication present field comprises 1 bit, the SSID present field comprises 1 bit, the internetworking present field comprises 1 bit, the bandwidth field comprises 3 bits, the security field comprises 1 bit, and the one or more reserved bits comprise 1 bit.

32. The method of claim 30, wherein a type field comprises a value of "11" and a subtype field comprises a value of "0001" to indicate that a beacon is a compressed beacon.

33. A wireless device configured to communicate in a wireless network, comprising:

a processor configured to generate a compressed beacon, the compressed beacon comprising:

a next full beacon time indication field that indicates, at least in part, timing of a full beacon that includes one or more fields not included in the compressed beacon; and

a frame control field comprising a next full beacon time indication present field, wherein the next full beacon time indication present field identifies whether the compressed beacon comprises the next full beacon time indication field; and

a transmitter configured to transmit the compressed beacon.

34. The wireless device of claim 33, wherein the next full beacon time indication field comprises a time at which the wireless device will transmit the full beacon.

35. The wireless device of claim 34, wherein the next full beacon time indication field comprises the 3 most significant bytes of the 4 least significant bytes of a next Target Beacon Transmit Time (TBTT).

36. The wireless device of claim 33, wherein the next full beacon time indication field comprises a flag indicating that the wireless device is to transmit the full beacon.

37. The wireless device of claim 36, wherein:

the processor is further configured to generate the full beacon, an

The transmitter is further configured to transmit the full beacon.

38. The wireless device of claim 33, wherein the next full beacon time indication field comprises a value indicating a duration until the wireless device transmits a next full beacon.

39. The wireless device of claim 38, wherein the next full beacon time indication field indicates a number of Time Units (TUs) until the wireless device transmits the next full beacon.

40. The wireless device of claim 39, wherein the next full beacon time indication comprises a null value when a number of beacon intervals to the next full beacon field is not determined.

41. The wireless device of claim 33, wherein the compressed beacon comprises:

the frame control field;

a source address;

a time stamp;

altering the sequence;

the next full beacon time indication field; and

and (5) checking the frame.

42. The wireless device of claim 41, wherein the frame control field comprises 2 bytes, the source address comprises 6 bytes, the timestamp comprises 4 bytes, the change sequence comprises 1 byte, the next full beacon time indication field comprises 3 bytes, and the frame check comprises 4 bytes.

43. The wireless device of claim 41, wherein the source address comprises a Basic Service Set Identification (BSSID) of the wireless device.

44. The wireless device of claim 41, wherein the timestamp comprises one or more least significant bits of a full timestamp.

45. The wireless device of claim 41, wherein the processor is further configured to: the change sequence is changed when an access point or network configuration changes or when there is a significant change in the content of the full beacon.

46. The wireless device of claim 41, wherein the frame control field comprises a version field, a type field, a subtype field, the next full beacon time indication present field, a Service Set Identifier (SSID) present field, an internetworking present field, a bandwidth field, a security field, and one or more reserved bits.

47. The wireless device of claim 46, wherein the version field comprises 2 bits, the type field comprises 2 bits, the subtype field comprises 4 bits, the next full beacon time indication present field comprises 1 bit, the SSID present field comprises 1 bit, the internetworking present field comprises 1 bit, the bandwidth field comprises 3 bits, the security field comprises 1 bit, and the one or more reserved bits comprise 1 bit.

48. The wireless device of claim 46, wherein a type field comprises a value of "11" and a subtype field comprises a value of "0001" to indicate that a beacon is a compressed beacon.

49. A wireless device configured to communicate in a wireless network, comprising:

a receiver configured to receive a compressed beacon, the compressed beacon comprising:

a next full beacon time indication field; and

a frame control field comprising a next full beacon time indication present field, wherein the next full beacon time indication present field identifies whether the compressed beacon comprises the next full beacon time indication field; and

a processor configured to:

operating the wireless device in a first power mode for a duration based on the next full beacon time indication field; and

transitioning the wireless device to a second power mode at the end of the duration,

wherein the wireless device consumes a first power when in the first power mode and a second power when in the second power mode, the first power being lower than the second power.

50. The wireless device of claim 49, wherein the next full beacon time indication field comprises a time at which an access point will transmit a full beacon comprising one or more fields not included in the compressed beacon.

51. The wireless device of claim 50, wherein the next full beacon time indication field comprises the 3 most significant bytes of the 4 least significant bytes of a next Target Beacon Transmit Time (TBTT).

52. The wireless device of claim 49, wherein the next full beacon time indication field comprises a flag indicating that an access point will transmit a full beacon comprising one or more fields not included in the compressed beacon.

53. The wireless device of claim 52, further comprising the receiver further configured to receive the full beacon after the processor transitions the wireless device to the second power mode.

54. The wireless device of claim 49, wherein the next full beacon time indication field comprises a value indicating a duration until an access point transmits a next full beacon.

55. The wireless device of claim 54, wherein the next full beacon time indication field indicates a number of Time Units (TUs) until the access point transmits the next full beacon.

56. The wireless device of claim 55, wherein the next full beacon time indication field comprises a null value when the number of beacon intervals to the next full beacon is not determined.

57. The wireless device of claim 49, wherein the compressed beacon comprises:

the frame control field;

a source address;

a time stamp;

altering the sequence;

the next full beacon time indication field; and

and (5) checking the frame.

58. The wireless device of claim 57, wherein the frame control field comprises 2 bytes, the source address comprises 6 bytes, the timestamp comprises 4 bytes, the change sequence comprises 1 byte, the next full beacon time indication field comprises 3 bytes, and the frame check comprises 4 bytes.

59. The wireless device of claim 57, wherein the source address comprises a Basic Service Set Identification (BSSID) of an access point.

60. The wireless device of claim 57, wherein the timestamp comprises one or more least significant bits of a full timestamp.

61. The wireless device of claim 57, further comprising:

a transmitter configured to transmit a probe request upon detecting a change in the change sequence;

wherein the processor is further configured to detect a change in the altered sequence; and

wherein the receiver is further configured to receive a probe response in response to the probe request.

62. The wireless device of claim 57, wherein the frame control field comprises a version field, a type field, a subtype field, the next full beacon time indication present field, a Service Set Identifier (SSID) present field, an internetworking present field, a bandwidth field, a security field, and one or more reserved bits.

63. The wireless device of claim 62, wherein the version field comprises 2 bits, the type field comprises 2 bits, the subtype field comprises 4 bits, the next full beacon time indication present field comprises 1 bit, the SSID present field comprises 1 bit, the internetworking present field comprises 1 bit, the bandwidth field comprises 3 bits, the security field comprises 1 bit, and the one or more reserved bits comprise 1 bit.

64. The wireless device of claim 62, wherein a type field comprises a value of "11" and a subtype field comprises a value of "0001" to indicate that a beacon is a compressed beacon.

65. An apparatus for communicating in a wireless network, comprising:

means for generating a compressed beacon, the compressed beacon comprising:

a next full beacon time indication field that indicates, at least in part, timing of a full beacon that includes one or more fields not included in the compressed beacon; and

a frame control field comprising a next full beacon time indication present field, wherein the next full beacon time indication present field identifies whether the compressed beacon comprises the next full beacon time indication field; and

means for transmitting the compressed beacon.

66. The device of claim 65, wherein the next full beacon time indication field comprises a time at which the device will transmit the full beacon.

67. The device of claim 66, wherein the next full beacon time indication field comprises the 3 most significant bytes, of the 4 least significant bytes of a next Target Beacon Transmit Time (TBTT).

68. The device of claim 65, wherein the next full beacon time indication comprises a flag indicating that the device is to transmit the full beacon.

69. The apparatus of claim 68, further comprising:

means for generating the full beacon; and

means for transmitting the full beacon.

70. The device of claim 65, wherein the next full beacon time indication field comprises a value indicating a duration until the device transmits a next full beacon.

71. The device of claim 70, wherein the next full beacon time indication field indicates a number of Time Units (TUs) until the device transmits the next full beacon.

72. The device of claim 71, wherein the next full beacon time indication field comprises a null value when the number of beacon intervals to the next full beacon is not determined.

73. The device of claim 65, wherein the compressed beacon comprises:

the frame control field;

a source address;

a time stamp;

altering the sequence;

the next full beacon time indication field; and

and (5) checking the frame.

74. The apparatus of claim 73, wherein the frame control field comprises 2 bytes, the source address comprises 6 bytes, the timestamp comprises 4 bytes, the change sequence comprises 1 byte, the next full beacon time indication field comprises 3 bytes, and the frame check comprises 4 bytes.

75. The device of claim 73, wherein the source address comprises a Basic Service Set Identification (BSSID) of the device.

76. The apparatus of claim 73, wherein the timestamp comprises one or more least significant bits of a full timestamp.

77. The apparatus of claim 73, further comprising: means for changing the change sequence when an access point or network configuration changes or when there is a significant change in the content of a full beacon.

78. The apparatus of claim 73, wherein the frame control field comprises a version field, a type field, a subtype field, the next full beacon time indication present field, a Service Set Identifier (SSID) present field, an internetworking present field, a bandwidth field, a security field, and one or more reserved bits.

79. The apparatus of claim 78, wherein the version field comprises 2 bits, the type field comprises 2 bits, the subtype field comprises 4 bits, the next full beacon time indication present field comprises 1 bit, the SSID present field comprises 1 bit, the internetworking present field comprises 1 bit, the bandwidth field comprises 3 bits, the security field comprises 1 bit, and the one or more reserved bits comprise 1 bit.

80. The apparatus of claim 78, wherein a type field comprises a value of "11" and a subtype field comprises a value of "0001" to indicate that a beacon is a compressed beacon.

81. An apparatus for communicating in a wireless network, comprising:

means for receiving a compressed beacon, the compressed beacon comprising:

a next full beacon time indication field; and

a frame control field comprising a next full beacon time indication present field, wherein the next full beacon time indication present field identifies whether the compressed beacon comprises the next full beacon time indication field; and

means for operating a wireless device in a first power mode for a duration based on the next full beacon time indication field; and

means for transitioning the wireless device to a second power mode at the end of the duration,

wherein the wireless device consumes a first power when in the first power mode and a second power when in the second power mode, the first power being lower than the second power.

82. The device of claim 81, wherein the next full beacon time indication field comprises a time at which an access point will transmit a full beacon comprising one or more fields not included in the compressed beacon.

83. The device of claim 82, wherein the next full beacon time indication field comprises the 3 most significant bytes of the 4 least significant bytes of a next Target Beacon Transmit Time (TBTT).

84. The device of claim 81, wherein the next full beacon time indication field comprises a flag indicating that an access point will transmit a full beacon comprising one or more fields not included in the compressed beacon.

85. The apparatus of claim 84, further comprising: means for receiving the full beacon after transitioning the wireless device to the second power mode.

86. The device of claim 81, wherein the next full beacon time indication field comprises a value indicating a duration until an access point transmits a next full beacon.

87. The device of claim 86, wherein the next full beacon time indication field indicates a number of Time Units (TUs) until the access point transmits the next full beacon.

88. The device of claim 87, wherein the next full beacon time indication field comprises a null value when the number of beacon intervals to the next full beacon is not determined.

89. The device of claim 81, wherein the compressed beacon comprises:

the frame control field;

a source address;

a time stamp;

altering the sequence;

the next full beacon time indication field; and

and (5) checking the frame.

90. The device of claim 89, wherein the frame control field comprises 2 bytes, the source address comprises 6 bytes, the timestamp comprises 4 bytes, the change sequence comprises 1 byte, the next full beacon time indication field comprises 3 bytes, and the frame check comprises 4 bytes.

91. The apparatus of claim 89, wherein the source address comprises a Basic Service Set Identification (BSSID) of an access point.

92. The apparatus of claim 89, wherein the timestamp comprises one or more least significant bits of a full timestamp.

93. The apparatus of claim 89, further comprising:

means for detecting a change in the altered sequence;

means for transmitting a probe request when a change in the change sequence is detected; and

means for receiving a probe response in response to the probe request.

94. The device of claim 89, wherein the frame control field comprises a version field, a type field, a subtype field, the next full beacon time indication present field, a Service Set Identifier (SSID) present field, an internetworking present field, a bandwidth field, a security field, and one or more reserved bits.

95. The device of claim 94, wherein the version field comprises 2 bits, the type field comprises 2 bits, the subtype field comprises 4 bits, the next full beacon time indication present field comprises 1 bit, the SSID present field comprises 1 bit, the internetworking present field comprises 1 bit, the bandwidth field comprises 3 bits, the security field comprises 1 bit, and the one or more reserved bits comprise 1 bit.

96. The device of claim 94, wherein a type field comprises a value of "11" and a subtype field comprises a value of "0001" to indicate that a beacon is a compressed beacon.