GB2573344A

GB2573344A - Communication methods and devices

Info

Publication number: GB2573344A
Application number: GB1807407.0A
Authority: GB
Inventors: Sevin Julien; Baron Stéphane; Viger Pascal; Nezou Patrice
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2018-05-04
Filing date: 2018-05-04
Publication date: 2019-11-06
Anticipated expiration: 2038-05-04
Also published as: GB201807407D0; GB2573344B

Abstract

The present invention provides communication methods in a wireless communication network comprising a plurality of network cells (BSS), each cell comprising at least one station (non-AP) managed by an access point (AP). Such a method comprises, at a station: receiving a Wake-Up Radio (WUR) frame comprising a WUR identifier; determining whether the WUR frame is for the attention of the station; depending on said determining, transmitting a message indicating that the WUR identifier identifies several stations belonging to several network cells of the wireless communication network. In response to the first message, a second message is transmitted to at least one station of the network cell, including WUR modification information.

Description

COMMUNICATION METHODS AND DEVICES

FIELD OF THE INVENTION

The present invention relates generally to communication networks and more specifically to methods and systems for communicating in a wireless communication network comprising a plurality of network cells (BSS), each cell comprising at least one station (non-AP) managed by an access point (AP).

The invention finds application in wireless communication networks, in particular in 802.1 Iba networks.

BACKGROUND OF THE INVENTION

In recent years, the number of battery-powered devices has increased strongly with cellular telephones, tablets, laptop computers, wearable devices, Internet of Things (loT) devices and so on. Consequently, nowadays, a key consideration in wireless system design is the optimal use of the power consumption.

In such a context, the IEEE 802.11 standard organization has launched a new task group, IEEE 802.1 Iba, in which the definition of an ultra-low power consumption Wake-Up Radio (WUR) module is studied.

A wireless device comprising a radio module compliant with the IEEE 802.11a/b/n/ac/ax standards, referred to as a PCR and coupled with a WUR module is considered. The objective of the WUR module is to wake up the PCR on-demand, only when it is necessary (e.g., only when there are data to transmit). In this way, the PCR can enter more frequently in doze mode; hence, the power consumption is reduced.

The power consumption requirements related to WUR module are very strong with an objective of drawing less than 100 microwatts when it is active. To achieve this, the size of each frame (called WUR frame) sent by a WUR module of an AP has to be reduced as much as possible (e.g., to a few bits) to reduce as much as possible the number of bits to decode. More specifically, since the address field of a WUR frame, which is called “WUR identifier” and identifies the WUR module to which the frame is addressed, is limited to a few bits (e.g., 12), a same address value may involuntarily address several non-AP stations of the communication network. In other words, two non-AP stations may have the same WUR identifier. Also, two stations associated with two different BSSIDs, meaning that they are in the coverage area of two different AP, may have the same WUR identifier. Consequently, each of the two non-AP stations may consider that the received frame is for its attention whereas the received frame is for the attention of only one of them.

In this context, the WUR reception process cannot only rely on the address field of the received WUR frame to consider that the received WUR frame is for its attention or not.

In order to distinguish two non-AP stations, the WUR module of the non-AP station additionally computes a frame check sequence (FCS) based on the BSSID. However, such computation requires important processing resources.

There is thus a need to improve existing communication methods implying a WUR module while reducing power consumption.

SUMMARY OF INVENTION

The present invention has been devised to address one or more of the foregoing concerns.

In this context, according to a first aspect of the invention, there is provided a communication method in a wireless communication network comprising a plurality of network cells (BSS), each cell comprising at least one station (non-AP) managed by an access point (AP), the method comprising, at a station:

receiving a Wake-Up Radio (WUR) frame comprising a WUR identifier; determining whether the WUR frame is for the attention of the station; depending on said determining, transmitting a message indicating that the WUR identifier identifies several stations belonging to several network cells of the wireless communication network.

Hence, when a collision occurs, the non-AP station informs the AP of the collision so that the AP can change the conflicting WUR ID if necessary. Thanks to this new signaling, the risk of collision is globally reduced.

Correspondingly, there is provided a communication device station in a wireless communication network comprising a plurality of network cells (BSS), each cell comprising at least one station (non-AP) managed by an access point (AP), the communication device station comprising at least one microprocessor configured for carrying out the following steps:

The communication device station has the same advantages as the method defined above.

Optional features of the invention are further defined in the dependent appended claims. Some of these features are explained here below with reference to a method, while they can be transposed into device features dedicated to a communication device station according to the invention.

According to embodiments, determining whether the WUR frame is for the attention of the station comprises determining whether the WUR identifier identifies the station, a group of stations to which the station belongs, or the access point managing the network cell of the station.

According to embodiments, the received WUR frame includes a frame check sequence (FCS) and determining whether the WUR frame is for the attention of the station comprises a FCS test comprising:

computing a frame check sequence (FCS) based on an identifier (BSSID) of the network cell to which the station belongs; and comparing the computed FCS with the FCS included in the WUR frame.

According to embodiments, the FCS is computed as the concatenation of the identifier of the network cell with at least one field of the WUR frame.

According to embodiments, computing the FCS comprises applying a hash function to at least part of the identifier of the network cell.

According to embodiments, the method comprises incrementing a counter each time it is determined that the WUR frame is not for the attention of the station, and transmitting said message is performed when the counter reaches a predetermined threshold. This is particularly interesting to handle false negatives, for instance due to the fact that the received WUR frame comprises an erroneous bit.

According to embodiments, the message also depends on the type of the WUR identifier comprised in the WUR frame.

According to embodiments, determining whether the WUR frame is for the attention of the station comprises:

retrieving a registered WUR frame previously received by the station;

performing a bitwise comparison between the received WUR frame and the registered frame; and if some bits differ between the received WUR frame and the registered frame, performing the FCS test as aforementioned.

Thanks to these embodiments, the power consumption is reduced since the FCS is not always performed, in particular it is not performed when the bitwise comparison is ok. This is because a FCS decoding is more costly than a bitwise decoding in terms of processing.

According to embodiments, the method further comprises, in case of negative determination, waking up a primary channel radio (PCR) module of the station and transmitting a message is performed by the PCR.

According to embodiments, the received WUR frame is a WUR beacon and the method further comprises updating WUR parameters of the station. Hence, the synchronization between the AP and the non-AP station is maintained.

According to embodiments, determining whether the WUR frame is for the attention of the station comprises determining whether the WUR identifier is a Wake-Up ID identifying the station, a Group ID identifying a group of stations to which the station belongs, or a Transmit ID identifying the access point managing the network cell of the station.

According to embodiments, the message is an Action Frame with a field Action Type indicating that a collision occurred.

According to embodiments, the message is an Action Frame with a field Action Type indicating that a collision occurred between Wake-Up ID identifiers, Group ID identifiers or Transmit ID identifiers.

According to a second aspect of the invention, there is provided a communication method in a wireless communication network comprising a plurality of network cells, each cell comprising at least one station (non-AP) managed by an access point (AP), the method comprising, at the access point:

receiving a first message indicating that a Wake-Up Radio (WUR) identifier identifies several stations belonging to several network cells of the wireless communication network;

in response to the first message, transmitting a second message to at least one station of the network cell including WUR identifier modification information.

Correspondingly, there is provided an access point in a wireless communication network comprising a plurality of network cells (BSS), each cell comprising at least one station (non-AP) managed by an access point (AP), the access point comprising at least one microprocessor configured for carrying out the following steps:

The access point has the same advantages as the method defined above.

Optional features of the invention are further defined in the dependent appended claims. Some of these features are explained here below with reference to a method, while they can be transposed into device features dedicated to any access point according to the invention.

According to embodiments, transmitting a second message comprises transmitting a Wake-Up broadcast frame designed to wake up all the stations of the network cell of the access point that are in doze mode, and the second message is a primary channel radio (PCR) broadcast frame including said WUR identifier modification information, the PCR broadcast frame being transmitted to all the stations of the network cell of the access point.

According to embodiments, transmitting a second message comprises: transmitting a WUR broadcast frame including said WUR identifier modification information to all the stations of the network cell of the access point that are in doze mode; and transmitting a PCR broadcast frame including said WUR identifier modification information to all the stations of the network cell of the access point that are awake.

According to embodiments, transmitting a second message to at least one station comprises:

If the station is in doze mode, transmitting a WUR unicast frame including said WUR identifier modification information to the station; and

If the station is awake, transmitting a PCR unicast frame including said WUR identifier modification information to the station.

According to embodiments, the WUR identifier modification information is a new WUR identifier.

According to embodiments, the WUR identifier modification information is an identifier of a hash function to be applied to compute a frame check sequence (FCS) of a WUR frame. For instance, the hash function may be based on the 12 first (or last) bits of the BSSID of the AP. It may be also based on XOR.

According to embodiments, the first message is an Action Frame with a field Action Type indicating that a collision occurred.

According to embodiments, the first message is an Action Frame with a field Action Type indicating that a collision occurred between Wake-Up ID identifiers, Group ID identifiers or Transmit ID identifiers.

According to embodiments, the second message is an Action Frame with a field WUR Parameters indicating a new Wake-Up ID, a new Group-ID or a new Transmit ID to apply.

According to embodiments, the second message is an Action Frame with a field WUR Parameters indicating a hash identifier.

According to a third aspect of the invention, there is a provided wireless communication network comprising a plurality of network cells (BSS), each cell comprising at least one communication device station as aforementioned and an access point as aforementioned.

According to a fourth aspect of the invention, there is provided a Wake-Up Radio (WUR) frame designed to be sent by a communication device station to an access point in a wireless communication network comprising a plurality of network cells (BSS), each cell comprising at least one station (non-AP) managed by an access point (AP), the WUR frame indicating a WUR identifier that identifies several stations belonging to several network cells of the wireless communication network.

According to embodiments, the WUR frame further comprises an identifier of a hash function to be applied to compute a frame check sequence (FCS) based on the WUR frame.

According to embodiments, the WUR frame comprises a field Action Type indicating that a collision occurred.

According to embodiments, the WUR frame comprises a field Action Type indicating that a collision occurred between Wake-Up ID identifiers, Group ID identifiers or Transmit ID identifiers.

According to embodiments, the WUR frame comprises a field WUR Parameters indicating a new Wake-Up ID, a new Group-ID or a new Transmit ID to apply.

According to embodiments, the WUR frame comprises a field WUR Parameters indicating a hash identifier.

Another aspect of the invention relates to a non-transitory computer-readable medium storing a program which, when executed by a microprocessor or computer system in a device, causes the device to perform any method as defined above.

The non-transitory computer-readable medium may have features and advantages that are analogous to those set out above and below in relation to the methods and devices.

At least parts of the methods according to the invention may be computer implemented. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a circuit, module or system. Furthermore, the present invention may take the form of a computer program product embodied in any tangible medium of expression having computer usable program code embodied in the medium.

Since the present invention can be implemented in software, the present invention can be embodied as computer readable code for provision to a programmable apparatus on any suitable carrier medium. A tangible carrier medium may comprise a storage medium such as a hard disk drive, a magnetic tape device or a solid state memory device and the like. A transient carrier medium may include a signal such as an electrical signal, an electronic signal, an optical signal, an acoustic signal, a magnetic signal or an electromagnetic signal, e.g. a microwave or RF signal.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages of the present invention will become apparent to those skilled in the art upon examination of the drawings and detailed description. Embodiments of the invention will now be described, by way of example only, and with reference to the following drawings.

Figure 1 illustrates a wireless communication system in which embodiments of the invention may be implemented;

Figure 2 is a block diagram showing an exemplary architecture of a communication device 200 according to embodiments of the present invention;

Figure 3 shows the format of a Wake-Up Radio (WUR) frame 300 as defined in the IEEE 802.1 Iba standard;

Figure 4 shows the format of an 802.11 MAC Action frame including a WUR Action field as defined in the IEEE 802.1 Iba standard;

Figure 5 including Figures 5a,5b and 5c, shows fields/subfields/values added to the WUR frame and 802.11 MAC Action frame (including a WUR Action field) formats shown in Figures 3 and 4, according to embodiments of the invention;

Figure 6 illustrates, using a flowchart, steps of a communication method during which a WUR frame is received by a non-AP station according to the IEEE 802.1 Iba standard;

Figure 7 illustrates, using a flowchart, general steps of a communication method during which a WUR frame is received by a non-AP station according to embodiments of the invention;

Figure 8 illustrates, using a flowchart, steps of a communication method during which a WUR frame is received by a non-AP station according to a first embodiment of the invention;

Figure 9 illustrates, using a flowchart, steps of communication method during which a WUR frame is received by a non-AP station according to a second embodiment of the invention;

Figure 10a illustrates, using a flowchart, steps of communication method during which a WUR frame is received by a non-AP station according to a third embodiment of the invention;

Figure 10b illustrates, using a flowchart, steps of communication method during which a WUR frame is received by a non-AP station according to an alternative of the third embodiment of the invention shown in Figure 10a;

Figure 11 illustrates, using a flowchart, steps of communication method during which a WUR frame is received by a non-AP station according to a fourth embodiment of the invention;

Figure 12 including Figures 12a and 12b, illustrates, using flowcharts, steps of communication methods during which a WUR identifier (Transmit ID) modification is signaled by an AP to the non-AP stations of its network cell according to embodiments of the invention;

Figure 13 illustrates, using a flowchart, steps of a communication method during which a WUR identifier (Wake-Up ID) modification is signaled by an AP to a given non-AP station according to embodiments of the invention.

DETAILED DESCRIPTION

In the following description, all the items referred to by the same numeral reference are identical.

Figure 1 illustrates a wireless communication system in which embodiments of the invention may be implemented.

Wireless communication system 100 includes three wireless devices, an Access Point (AP) 110 and two non-AP stations 120 and 130. Each device comprises two wireless communication modules. A first one, referred to as the primary connectivity radio (PCR), corresponds to the main radio thought which wireless data are exchanged. It may be compliant with IEEE 802.11 standard technology, for instance as defined in 802.11a/b/n/ac/ax standards. A second one, referred to as Wake-Up radio (WUR) or WUR module or Wake-Up receiver, corresponds to the companion radio of PCR. It is a low-power-consumption radio one objective of which is to wake up the PCR of a non-AP station only when the PCR has data to send or receive from another radio.

Correspondingly, the AP 110 includes a PCR 112 and a WUR 114, the nonAP station 120 includes a PCR 122 and a WUR 124 and the non-AP station 130 includes a PCR 132 and a WUR 134.

A wireless communication module is considered OFF or in doze mode when it is not able to receive and transmit data. Inversely, a wireless communication is considered ON (i.e. set to ON) or awake when it is able to receive and transmit data. Basically, in a non-AP station, when the PCR is OFF, the WUR is ON and inversely when the PCR is ON, the WUR is OFF. In an alternative embodiment, the WUR may be always ON.

A shown in Figure 1, the non-AP station 120 has a PCR 122 OFF and a WUR 124 ON and the non-AP station 130 has a PCR 132 ON and a WUR 134 OFF. Consequently, the use of the WUR radio allows the power consumption of the non-AP station 120 to be reduced because its PCR is OFF.

As the PCR 132 is ON, the frames 190, referred to as PCR frames, may be exchanged between the PCR 112 of the AP 110 and the PCR 132 of the non-AP station 130 as during a typical wireless IEE 802.11 transmission session. Such PCR frames 190 are not received by the PCR 122 of the non-AP station 120 because this one is OFF.

When the AP 110 has PCR data to send to the non-AP station 120, it needs to wake up the PCR 122. To do so, it uses its WUR 114 to transmit a frame 180, referred to as a WUR frame. A WUR frame consists of a legacy IEEE 802.11 preamble and a payload modulated by a so-called ON-OFF key (OOK) scheme. As described further hereafter with reference to Figure 3, the WUR frame comprises synchronization information, a receiver’s address and other transmission information. A WUR Wake-Up frame is a particular type of WUR frame which is used to wake up the PCR module of the non-AP station. Such a WUR Wake-Up frame 180 is received by the WUR 124 of the non-AP station 120. This latter, after checking that the WUR Wake-Up frame 180 is for its attention, generates a Wake-Up signal 185 for the attention of the PCR 122 to wake up it. At this instant, the PCR 122 becomes ON, the WUR 124 may become OFF and a PCR transmission may be initiated between the PCR 112 of the AP 110 and the PCR 122 of the non-AP station 120.

In the following description, as the PCR is the main communication module, a non-AP station is said in doze mode when its PCR is OFF and awake when its PCR is ON.

Moreover, when the power management is activated between an AP and a non-AP station, a non-AP station is either in active mode or in Power Saving (PS) mode. In active mode, the non-AP station may receive and transmit frames at any time. In other words, the non-AP station is always awake. In PS mode, the non-AP station is awake only when frames have to be received or transmitted. The non-AP station is thus in doze mode otherwise. Nevertheless, in doze mode, a non-AP station may wake up periodically to listen to beacon frames (sent by the AP) which may comprise a Traffic indication map (TIM) indicating that it is necessary for the station to enter in an awake state. Moreover, in doze mode, a non-AP station is able to send dedicated frames (PS-Poll) to the AP in order to enter latter in an awake state (to transmit data). Consequently, at any time, an AP may know the state of a non-AP station (i.e. whether a non-AP station is in doze mode or awake).

Figure 2 is a block diagram showing an exemplary architecture of a communication device 200 according to embodiments of the present invention. For instance, the communication devices 200 may correspond to the Access Point 110 or to the non-AP station 120/130 of the communication system 100 shown in Figure 1.

For illustration purposes only, the communication device 200 may be a vehicle, a home appliance or another embedded item with electronics, software, sensors and connectivity enabling objects to connect and exchange data. More specifically, it is well adapted for device referred to as Internet of Things (loT) devices that are battery powered and require low-power operation and communication.

In this example, the communication device 200 comprises a communication bus 213 to which there are preferably connected:

• a central processing unit 211, such as a microprocessor, denoted CPU;

• a read only memory 207, denoted ROM, for storing computer programs for implementing the invention;

• a random access memory 212, denoted RAM, for storing the executable code of methods according to embodiments of the invention as well as the registers adapted to record variables and parameters necessary for implementing methods according to embodiments of the invention; more specifically, the RAM 212 may store a list of predetermined WUR identifiers hash functions, each one being characterized by a hash identifier;

• at least one communication interface 202 including a PCR and a WUR. The frames are written from a FIFO sending memory in the RAM 212 to the network interface for transmission or, they are read from the network interface for reception and written into a FIFO receiving memory in the RAM 212 under the control of a software application running in the CPU 211.

Optionally, the communication device 200 may also include the following components:

• a data storage means 204 such as a hard disk, for storing computer programs for implementing methods according to one or more embodiments of the invention;

• a disk drive 205 for a disk 206, the disk drive being adapted to read data from the disk 606 or to write data onto said disk;

• a screen 209 for displaying decoded data and/or serving as a graphical interface with a user, by means of a keyboard 210 or any other pointing means.

The communication device 200 may be optionally connected to various peripherals, such as for example a digital camera 208, each being connected to an input/output card (not shown) so as to supply data to the communication device 200.

Preferably the communication bus provides communication and interoperability between the various elements included in the communication device 200 or connected to it. The representation of the bus is not limiting and in particular the central processing unit is operable to communicate instructions to any element of the communication device 200 directly or by means of another element of the communication device 200.

The disk 206 may optionally be replaced by any information medium such as for example a compact disk (CD-ROM), rewritable or not, a ZIP disk, a USB key or a memory card and, in general terms, by an information storage means that can be read by a microcomputer or by a microprocessor, integrated or not into the apparatus, possibly removable and adapted to store one or more programs whose execution enables a method according to the invention to be implemented.

The executable code may optionally be stored either in the read only memory 207, on the hard disk 204 or on a removable digital medium such as for example the disk 206 described previously. According to an optional variant, the executable code of the programs can be received by means of the communication network 203, via the interface 202, in order to be stored in one of the storage means of the communication device 600, such as the hard disk 204, before being executed.

The central processing unit 211 is preferably adapted to control and direct the execution of the instructions or portions of software code of the program or programs according to the invention, which instructions are stored in one of the aforementioned storage means. On powering up, the program or programs that are stored in a non-volatile memory, for example on the hard disk 204 or in the read only memory 207, are transferred into the random access memory 212, which then comprises the executable code of the program or programs, as well as registers for storing the variables and parameters necessary for implementing the invention.

In a preferred embodiment, the apparatus is a programmable apparatus which uses software to implement the invention. However, alternatively, the present invention may be implemented in hardware (for example, in the form of an Application Specific Integrated Circuit or ASIC).

Figure 3 shows the format of a Wake-Up Radio (WUR) frame 300 as defined in the IEEE 802.1 Iba standard.

The WUR frame 300 comprises a “Frame Control” field 310, an “Address” field 320, a “TD Control” field 330, a “Frame Body” field 340 and a “FCS” field 350. “FCS” is for Frame Check Sequence. It is for instance a so-called CRC.

The fields 310, 320 and 330 form the MAC header of the WUR frame. The MAC header and “FCS” field 350 form the minimal WUR frame format and are present in all WUR frames.

The “Frame Control” field 310 comprises a “Type” subfield 311 and a “Reserved” subfield 315. The “Type” subfield 311 indicates the type of the WUR frame, referred to as WUR frame type. It is coded on 3 or 4 bits. Four WUR frame types are defined and listed in the table 312: “WUR Beacon” coded by value 0, “WUR Wake-Up” coded by value 1, “WUR Vendor Specific” coded by value 2 and “WUR Discovery” coded by value 3.

The “Address” field 320 comprises an identifier for the WUR frame, referred to as a WUR identifier. It is coded on 12 bits. Three WUR identifiers are defined and listed in the table 325: “Transmit ID”, “Group ID”, and “Wake-Up ID”. “Transmit ID” corresponds to an identifier of the transmitting AP so that a frame including such a Transmit ID is for the attention of all the stations controlled by the identified AP. “Group ID” corresponds to an identifier of a group of non AP stations comprising a WUR module. “Wake-Up ID” corresponds to an Identifier of a given (targeted) non-AP station.

The “Frame Body” field 340 is a variable-length field that comprises information specific to specific individual WUR frame types.

The “FCS” field 350 may comprise a Cyclic Redundancy Check (CRC). The size of CRC may be CRC-8, CRC-16 or CRC-32. The FCS is calculated over at least some or all the fields of the WUR frame, e.g., the “Frame Control” field 310, the “Address” field 320, the “TD Control” field 330, the “Frame Body” field (if present) 340, and also a BSSID value. These fields are referred to as the calculation fields. The BSSID value is part of the calculation but it is not included in the WUR frame transmitted over the wireless medium.

The format of each WUR frame inherits from its general WUR frame format and according to its WUR frame type, some fields are present or not.

Hence, the frame format of a WUR Beacon frame may comprise all fields but the “Frame Body” field 340. For this frame, the “Type” subfield 311 of the ’’Frame Control” field 310 is set to 0, and the “Address” field 320 may comprise the “Transmit ID”.

As another example, the frame format of the WUR Wake-Up frame may comprise all fields. For such a frame, the “Type” subfield 311 of the ’’Frame Control” field 310 is set to 1, the “Address” field 320 comprises the ”Wake-Up ID” of the targeted non-AP station when the WUR frame is individually addressed, the ’’Group ID” when the WUR frame is addressed to a group of stations, the “Transmit ID” when the WUR frame is broadcast and 0 when multiple “Wake-Up ID” are included in the frame body of the WUR frame 340.

Figure 4 shows the format of an 802.11 MAC Action frame including a WUR Action field as defined in the IEEE 802.1 Iba standard. In such a case, the frame is referred to as WUR Action frame. It is recalled that an 802.11 MAC Action frame is a management frame used to trigger an action. A WUR Action frame is used to negotiate the parameters related to WUR operations in the primary connectivity radio.

The WUR Action frame 410 comprises an “Action” field 425 (referred to as WUR Action field) in its “Frame Body” field 420.

The “Action” field 425 comprises a WUR Mode Element” field 460 that is used to negotiate the parameters related to WUR operations. It comprises an “Action Type” field 476, a “WUR Mode Response Status” field 478 and a “WUR Parameters” field 480.

The “Action Type” field 476 comprises a number that identifies the type of WUR mode operation. It may be coded on 8 bits. Six types of WUR mode operations are defined and listed in table 477: “Enter WUR Mode Request” coded by value 0, “Enter WUR Mode Response” coded by value 1, “Enter WUR Mode Suspend Request” coded by value 2, “Enter WUR Mode Suspend Response” coded by value 3, “Enter WUR Mode Suspend” coded by value 4 and “Enter WUR Mode” coded by value 5. The values between 6 and 255 are reserved.

The “WUR Mode Response Status” field 478 indicates the status returned by the AP responding to the non-AP STA’s WUR Mode request operation. This field is valid only when the “Action Type” field 476 is set to “Enter WUR Mode Response” or “Enter WUR Mode Suspend Response” and is reserved otherwise. Two status are defined: “Accept” coded by value 0 and “Denied” coded by value 1.

The “WUR Parameters” field 480 comprises several subfields. If the WUR Action frame 410 is sent from the WUR module of the AP, it comprises a list of subfields 481 including a “WUR ID” subfield 482 and a “Duty Cycle Information” subfield 483. The “WUR ID” subfield 482 corresponds to the WUR identifier that uniquely identifies a station within the BSS managed by the AP, referred to as Wake-Up ID.

Figure 5 including Figures 5a, 5b and 5c, shows fields/subfields/values added to the WUR frame and 802.11 MAC Action frame (including a WUR Action field) formats shown in Figures 3 and 4, according to embodiments of the invention.

Figure 5a represents a table 512 listing the WUR frame types according to embodiments of the invention. In addition to the current version of IEEE 802.11ba (illustrated by the table 312), a first new WUR frame type referred to as “WUR Broadcast Identifiers modification” is defined and coded by value 4 and a second new WUR frame type referred to as “WUR Unicast Identifiers modification” is defined and coded by value 5. Obviously, other code values can be used.

Figure 5b represents a table 577 listing the types of WUR mode operation according to embodiments of the invention. In addition to the current version of the IEEE 802.11ba (illustrated by the table 477), five new types of WUR mode operation are defined: “WUR identifiers collision identification” coded by value 6, “Wake-Up ID collision identification” coded by value 7, “Transmit ID collision identification” coded by value 8, “Group ID collision identification” coded by value 9, and “WUR identifiers collision identification response” coded by value 10. Obviously, only certain of these values could be used and other values can be used.

Figure 5c represents a list of subfields 581 included in a “WUR Parameters” field 480 of a “WUR Mode Element” of a WUR action frame 410. In addition to the current version of the IEEE 802.1 Iba, a first new subfield “Transmit ID” 584 is defined corresponding to a new Transmit ID to be applied (by the non-AP stations), a second new subfield “Hash Identifier” 585 is defined corresponding to a new identifier of a predetermined WUR identifiers hash function to be applied (by the non-AP stations), a third new subfield “Wake-Up ID” 586 is defined corresponding to a new Wake-up ID to be applied (by the intended non-AP station), and a fourth new subfield “Group ID” 587 is defined corresponding to a new Group ID to be applied (by the targeted non-AP stations).

Figure 6 illustrates, using a flowchart, steps of a communication method during which a WUR frame is received by a non-AP station according to the IEEE 802.1 Iba standard. These steps are performed by the WUR module 124 of the non-AP station, when the WUR module of the non-AP station is ON only. It is assumed that the WUR negotiation between the WUR module of the AP and the WUR module of the nonAP station has been already done, e.g., that a Wake-Up ID has been assigned to the nonAP station. Optionally, some group IDs may also be assigned to the non-AP station. Moreover, the non-AP station knows the Transmit ID of the AP with which it is associated. The non-AP station also knows the BSSID (also referred to as “Embedded BSSID”) of the BSS to which it belongs.

At step 600, a WUR frame is received by the non-AP station.

At step 610, the “Address” field 320 of the WUR frame is read.

At step 620, the non-AP station checks whether the address field comprises its Wake-Up ID, or the Transmit ID of the AP with which it is associated, or a Group ID to which it belongs (for which it is registered). If so, the next step is 630. If not, the next step is 650.

At step 650, the non-AP station discards the received WUR frame because it is not for its attention or because of a transmission error that has resulted in an address modification.

At step 630, the non-AP station computes a FCS based on the received WUR frame. For example, the calculation takes into account the fields 310, 320, 330 and 340 of the received WUR frame and the Embedded BSSID.

At step 640, the non-AP station checks whether the FCS computed at step 630 is equal to the received FCS included in the field 350 of the received WUR frame. If so, the next step is 660. If not, the next step is 650. The difference between the computed FCS and the received FCS may be explained in several ways. For example, this may be due to the fact that the received WUR frame comprises at least one erroneous bit (e.g., due to an error transmission). This may also be due to the fact that the received WUR frame does not come from the AP with which the non-AP station is associated. In other words, the computed FCS has been computed based on the BSSID with which the nonAP station is associated and the received FCS has been computed based on another BSSID with which the non-AP station is not associated. The problem is that the test performed at step 620 may succeed even if the frame is not addressed to the considered non-AP station (i.e. the station performing this test). As a matter of fact, collisions may occur between the WUR identifiers (e.g., coded with 12 bits while 48 bits may be necessary). Step 640 is then necessary to determine if a collision occurred or not. There is a collision when two devices in the communication system are associated with two different APs (characterized by two BSSIDs) but have the same WUR identifier. This is because two different AP may assign the same WUR identifier for two devices (i.e. one device associated with each AP). The main reason is that a WUR identifier is only coded on 12 bits. One objective of the invention is to fix this persistent situation (in the priorart, the WUR identifier assignment is only done during the WUR negotiation). As will be described hereafter, embodiments of the invention allow steps 630 and 640 not to be performed.

At step 660, the non-AP station performs the WUR Processing defined in the IEEE 802.11ba standard, which consists in waking up the PCR (with a Wake-Up signal 185) if the received WUR frame is a WUR Wake-Up frame. For example, if the received WUR frame is a WUR beacon, the synchronization WUR parameters are updated. If the received WUR frame is a WUR beacon, the synchronization WUR parameters are updated (in order to maintain the synchronization between the AP and the non-AP station).

Figure 7 illustrates, using a flowchart, general steps of a communication method during which a WUR frame is received by a non-AP station according to embodiments of the invention. In these embodiments, a step to inform the AP that a WUR identifiers collision occurred is performed.

These steps are performed in the WUR of the non-AP station and consequently they are applied only when the WUR of the non-AP station is ON (124). In the given example, it is assumed that the WUR negotiation between the AP and a nonAP station has been done already. It means that a Wake-Up ID has been assigned to the non-AP station. Optionally, some group IDs may also be assigned to the non-AP station. Moreover, the non-AP station may know the Transmit ID of the AP with which it is associated. The non-AP station also knows the BSSID (also referred to as “Embedded BSSID”) of the BSS to which it belongs.

A detailed description of steps 600, 610, and 660 can be found in the description of Figure 6.

According to embodiments of the present invention, new ways of computing the FCS at step 630 are proposed.

For example, the FCS may be computed as (frame body (340) | BSSID), with being the concatenation operator. In an alternative, another hash function may be considered: e.g., FCS = fingerprint(BSSID). In that case, the integrity of data is not checked. In another alternative, only a part of the BSSID may be considered instead of the full BSSID.

At step 720, it is determined whether a WUR identifiers collision occurred.

If a WUR identifiers collision occurred, the next step is step 730. If not, the next step is step 660. If the received WUR frame is a WUR beacon, the synchronization

WUR parameters are updated (in order to maintain the synchronization between the AP and the non-AP station).

At step 730, the PCR of the non-AP station is waken up. To do so, the nonAP station generates and sends a dedicated internal Wake-Up signal 185 indicating that a collision occurred, to the PCR.

At next step 740, the PCR generates a WUR Action frame indicating that a collision occurred (and that consequently, a WUR identifiers modification may be necessary). Its “Action Type” field 476 may be assigned according to the table 577 described with reference to Figure 5. The generated frame is then transmitted through the Primary Channel Radio. One may note that contrary to the previous steps, the step 740 is performed at PCR level (122).

According to an alternative implementation, the WUR module generates the WUR Action frame indicating that a collision has occurred, and sends it to the PCR. The PCR then transmits it through the Primary Channel Radio.

Four embodiments of the communication method are described hereafter with reference to Figures 8, 9, 10 and 11.

For the first, second and fourth embodiments that are described hereafter with reference to Figures 8, 9 and 11 respectively, the “Action Type” field 476 is coded by value 6 corresponding to “WUR identifiers collision identification”.

According to embodiments illustrated in Figures 10a and 10b, the output of step 720 may be more accurate and may indicate that the WUR identifier to be modified corresponds to a Transmit ID, a Wake-Up ID or a Group ID. More specifically, if a Transmit ID modification is required, the “Action Type” field 476 may be coded by value 8 corresponding to “Transmit ID collision identification”. Alternatively, if a Wake-Up ID modification is required, the “Action Type” field 476 may be coded by value 7 corresponding to “Wake-Up ID collision identification”. Alternatively, if a Group ID modification is required, the “Action Type” field 476 may be coded by value 9 corresponding to “Group ID collision identification”.

Figure 8 illustrates, using a flowchart, steps of a communication method during which a WUR frame is received by a non-AP station according to a first embodiment of the invention.

A detailed description of steps 600, 610, 620, 630 and 640 can be found in the description of Figure 6.

In this first embodiment, when it is determined at step 640 that the computed FCS differs from the FCS received in the WUR frame (i.e. output is no), a step 880 is performed.

At step 880, the non-AP station concludes that a collision occurred and that consequently, a WUR identifiers modification may be necessary. In such a case, the nonAP station informs the AP that a collision occurred and the received WUR frame is discarded because it is considered not for the attention of the non-AP station (for instance due to a wrong BSSID).

On the contrary, when it is determined that the computed FCS and the received FCS correspond, the non-AP station concludes (at step 890) that there is no collision.

This first embodiment thus allows determination that a collision occurred and information of the AP as soon as the computed FCS is not equal to the received FCS. Consequently, it is very reactive.

Figure 9 illustrates, using a flowchart, steps of communication method during which a WUR frame is received by a non-AP station according to a second embodiment of the invention.

In this second embodiment, the WUR identifiers modification is conditioned by the reception of several WUR frames for which a collision occurred. It is particularly interesting to handle cases where the computed FCS is not equal to the received FCS because the received WUR frame comprises a least one erroneous bit, for example due to a transmission error.

To this end, a counter referred to as modifcounterl and an associated threshold referred to as modifthresholdl are used. It is assumed that the value of the threshold is predetermined and is strictly greater than one. One may note that the case of value one corresponds to the algorithm described with reference to Figure 8.

In this second embodiment, when it is determined at step 640 that the computed FCS differs from the FCS received in the WUR frame (i.e. output is no), a step 950 is performed.

At step 950, the non-AP station increments a counter modif counterl by 1 and the next step is 955. At step 955, the non-AP station checks whether the value of the counter modif counterl is less than a predetermined threshold modif thresholdl.

If so, the next step is 890 where the non-AP station concludes that there is no need to inform the AP of the collision. A detailed description of step 890 can be found in the description of Figure 8.

If not, the non-AP station concludes that a collision occurred and that consequently, a WUR identifiers modification may be necessary and the non-AP station informs the AP that a collision occurred as in step 880 of Figure 8. A detailed description of step 880 can be found in the description of Figure 8.

On the contrary, when it is determined (at step 640) that the computed FCS and the received FCS correspond, the next step is 960 during which the non-AP station initializes the counter modif counterl to zero. Then, the non-AP station concludes (step 890 as in Figure 8) that there is no need to inform the AP of any collision as it considers that no WUR identifiers collision occurred.

Figure 10a illustrates, using a flowchart, steps of communication method during which a WUR frame is received by a non-AP station according to a third embodiment of the invention.

In this third embodiment, the algorithm takes into account the type of WUR identifier included the Address field (field 320) of the received WUR frame. If the WUR identifier is a Wake-Up ID, the algorithm is reactive as the algorithm described with reference to Figure 8 because the AP is informed as soon as it is determined that the computed FCS is not equal to the received FCS. If the WUR identifier is a Transmit ID or a Group ID, the WUR identifiers modification is conditioned by the reception of several consecutives WUR frames as in the algorithm described with reference to Figure 9.

The signaling by an AP to non-AP stations of the new selected WUR identifier (when the AP has received a message indicating that a collision occurred) makes the overall process more costly when the WUR identifier is a Transmit ID or Group ID than a Wake-Up ID. This is because in the first cases, (Transmit ID or Group ID), the signaling is based on a broadcast frame that has to be processed by all the stations (of the group) whereas in the second case (Wake-Up ID), it is only based on unicast frames hence only the targeted station has to process the frame.

In practice, according to this third embodiment, a counter referred to as modif_counter2 and an associated threshold referred to as modif_threshold2 are used to count Transmit ID (and Group ID) collisions.

In this third embodiment, when it is determined at step 640 that the computed FCS differs from the FCS received in the WUR frame (i.e. output is no), a step 1045 is performed.

At step 1045, the non-AP station checks whether the address field corresponds to its Wake-Up ID. If so, it concludes that there has been a collision and informs the AP of it at step 1081. To do so, the non-AP station may send a message including an Action Type field set to 7 (“Wake-Up ID collision identification”) as defined in the table 577.

If the address field does not correspond to the Wake-Up ID of the non-AP station, the process goes to step 1050. This step 1045 may also be performed in the embodiments described with reference to Figures 8, 9, and 11 in order to indicate whether the WUR identifiers modification concerns a Wake-Up ID or a Transmit ID (or Group ID).

At step 1050, the non-AP station increments the counter modif_counter2 by 1 and then performs the next step 1055.

At step 1055, the non-AP station checks whether the value of the counter modif_counter2 is less than a predetermined threshold modif_threshold2. If not, it concludes that there has been a collision (between Transmit IDs or Group IDs) and informs the AP of it at step 1082. To do so, the non-AP station may send a message including an Action Type field set to 8 (“Transmit ID collision identification”) or 9 (“Group ID collision identification”) as defined in the table 577.

If the value of the counter modif_counter2 is less than the predetermined threshold modif_threshold2, the non-AP station concludes (step 890 as in Figure 8) that there is no need to inform the AP of any collision. A detailed description of step 880 can be found in the description of Figure 8.

On the contrary, when it is determined (at step 640) that the computed FCS and the received FCS correspond, the next step is 1060 during which the non-AP station initializes the counter modif_counter2 to zero. Then, the non-AP station concludes (step 890 as in Figure 8) that there is no need to inform the AP of any collision as it considers that no WUR identifiers collision occurred. A detailed description of step 890 can be found in the description of Figure 8.

Figure 10b illustrates, using a flowchart, steps of communication method during which a WUR frame is received by a non-AP station according to an alternative of the third embodiment of the invention shown in Figure 10a.

In practice, according to this alternative, a new counter referred to as modif_counter3 and an associated threshold referred to as modif_threshold3 are used to count Group ID collisions. The non-AP station may initialize the counter modif_counter3 to zero at step 1060.

In this alternative, the non-AP station determines at step 1045 whether the Address field corresponds to a Wake-Up ID, a Group ID or a Transmit ID.

In the case of a Wake-Up ID, step 1081 is performed as described with reference to Figure 10a.

In the case of a Transmit ID, steps 1050 and 1055 are performed as described with reference to Figure 10a.

In the case of a Group ID, the non-AP station increments a new counter modif_counter3 by 1 at step 1070 and then performs the next step 1075.

At step 1075, the non-AP station checks whether the value of the counter modif_counter3 is less than a predetermined threshold modif_threshold3. If not, it concludes that there has been a collision (between Group IDs) and informs the AP of it at step 1082. To do so, the non-AP station may send a message including an Action Type field set to 9 (“Group ID collision identification”) as defined in the table 577.

If the value of the counter modif_counter3 is less than the predetermined threshold modif_threshold3, the non-AP station concludes (step 890 as in Figure 8) that there is no need to inform the AP of any collision.

Figure 11 illustrates, using a flowchart, steps of communication method during which a WUR frame is received by a non-AP station according to a fourth embodiment of the invention.

This embodiment allows the FCS not to be performed when a same WUR frame as received previously is received again. This is typically the case for Wake-Up frames.

For these purposes, a bitwise decoding (bits comparison - step 1165) is performed in a first phase in order to check whether the received frame is already known by the station . In this way, the FCS is computed only if the frame has never been received before. This allows power consumption to be reduced as a FCS decoding is more costly than a bitwise decoding in terms of processing.

In this third embodiment, when it is determined at step 620 that the address field comprises its Wake-Up ID, or the Transmit ID of the AP with which it is associated, or a Group ID to which it belongs (for which it is registered), a step 1115 is performed. Otherwise, the received WUR frame is discarded because it is considered not intended to the non-AP station (assumption: wrong address) and the non-AP station concludes (step 890 as in Figure 8) that there is no need to inform the AP of any collision. A detailed description of step 890 can be found in the description of Figure 8.

At step 1115, the non-AP station checks whether the received WUR frame is “already registered” or not, the registration being done at step 1170. The check is based on the address field. If the address field corresponds to the “registered WUR identifier” (done at step 1170), the received WUR frame is considered as “already registered” and the next step is 1165. If not, the received WUR frame is considered “non registered” and the next step is step 630 as in Figure 6.

Then, when at step 640 (as in Figure 6), it is determined that the computed FCS is different from the received FCS (output is no), the non-AP station concludes that a WUR identifiers collision occurred and thus the AP should be informed of it (step 880 as in Figure 8). A detailed description of step 880 can be found in the description of Figure 8.

In this case the WUR frame is discarded. Otherwise, if the computed FCS and the received FCS correspond (output of step 640 is yes), the process goes to step 1170 where the WUR is registered.

At step 1170, the non-AP station registers the received WUR frame. More precisely, it means that all bits of the received WUR frame are stored and the WUR frame is referred to as “registered WUR frame”. Moreover, the WUR identifier (comprised in its address field 320) is also stored. It is referred to as “registered WUR identifier” and it is used in step 1115. The next step is step 890 (as in Figure 8). A detailed description of step 890 can be found in the description of Figure 8.

When the WUR frame is already registered (output of test 1115 is yes), the non-AP station performs a Bitwise comparison (step 1165) between the registered WUR frame and the received WUR frame (by performing a XOR operation for instance) and the result is checked at step 1168. If at least one bit at the same position is different between the registered WUR frame and the received WUR frame, the result is considered not OK and the next step is step 630 (as in Figure 6). If not, the result is considered as OK and the next step is 890 (as in Figure 8). In such a case, the costly computing of the FCS at step 630 has been advantageously avoided.

According to embodiments, steps of the algorithms described with reference to Figures 9, 10, 11 can be combined. For instance, both modif counterl and modif_counter2 can be used, with their associated respective threshold modif thresholdl and modif_threshold2. In an embodiment, steps 1115, 1165, 1168 and 1170 may be introduced in algorithms described with reference to Figures 9 and 10.

Figure 12 including Figures 12a and 12b, illustrates, using flowcharts, steps of communication methods during which a WUR identifier modification is signaled by an AP to the non-AP stations of its network cell according to embodiments of the invention. In these embodiments, a new value of the Transmit ID is required.

It is recalled that within the wireless communication system 100, some nonAP stations are awake and others are in doze mode. When a non-AP station is in doze mode, it is not able to receive PCR frames but it is able to receive WUR frames from AP. When a non-AP station is not in doze mode, i.e. it is awake, it is able to receive PCR frames and in some cases, it may be able to receive WUR frames.

According to a first embodiment shown in Figure 12a, the AP wakes up all non-AP stations in doze mode through its WUR module and sends them a WUR identifier modification information through its PCR module (inside a PCR frame).

At step 1201, the AP receives a message indicating that a collision occurred and that a WUR identifiers modification may be necessary (typically further to the signalling performed by a non-AP station at step 740 shown in Figure 7), the AP may select a new WUR identifier (for instance a new Transmit ID) and signal it to all its stations.

In another embodiment, the algorithm here described may be launched when the AP receives an unexpected PCR frame. Such a case may occur when a non-AP station receives a Wake-Up WUR frame and processes it by error. For instance, it may happen when the Wake-Up WUR frame comprises some erroneous bits and nevertheless, its address field (read at step 610 of Figure 6) corresponds to the Transmit ID or group ID in which the non-AP station is registered, or the Wake-Up ID of the non-AP station and the received FCS corresponds to the computed FCS (output of step 640 is yes).

At step 1205, the AP determines a WUR identifier modification information.

In an embodiment, the WUR identifier modification information is directly a new value of the Transmit ID. For instance, this new value can be selected randomly among a value range between 1 and 2047 excluding the Wake-Up ID of the non-AP stations already assigned by the AP.

In another embodiment, the WUR identifier modification information corresponds to an identifier of a hash function to be applied to compute the FCS. A WUR identifiers hash function is a function which may compute a value of Transmit ID on 12 bits from a BSSID coded on 48 bits. In this case, the hash function is a fingerprint function.

The AP and non-AP stations may store (in the random access memory 212) a predetermined list of WUR identifiers hash functions they can implement. For instance, a fingerprint function may be the 12 first (or last) bits of the BSSID of the AP. It may be also based on XOR. For instance, it may be equal to BSSIDfO: 11] XOR BSSID[12: 23] XORBSSID[24: 35] XORBSSID[36: 47], BSSID[k,l] corresponding to the (1-k) bits of the BSSID of the AP between the k^th bit and the 1^th bit. it may be equal to BSSID[24: 35] XOR BSSID[36: 47], BSSID[k,l] corresponding to the (1-k) bits of the BSSID of the AP between the k^th bit and the 1^th bit.

One may note that the predetermined list of WUR identifiers hash functions is preferably the same between the AP and all non-AP stations. Similarly, the hash identifiers may correspond to the same WUR identifiers hash functions.

Next, at step 1210, the AP generates a broadcast WUR Wake-Up frame as described with reference to Figure 3. More specifically, the Type subfield 311 of its Frame control field 310 is set to 1, and its Address field 320 is set to its current Transmit ID. One should note that the Address field 320 is not set to the Transmit ID determined at step 1205.

At step 1220, the AP sends the Broadcast WUR Wake-Up frame generated at step 1210 through the WUR module. On one hand, this broadcast WUR Wake-Up frame may be ignored by the awake non-AP station. On the other hand, this broadcast WUR Wake-Up frame may Wake-Up all stations in doze mode. Hence, all non-AP stations of the wireless communication system 100 are awake at the end of this step.

At step 1230, the AP generates a Broadcast PCR frame including the WUR identifier modification information (to be sent). To do so, the AP generates a WUR Action frame as described with reference to Figure 4. Its Action Type field 476 is assigned according to the table 577 described with reference to Figure 5 and is set to 10 corresponding to “WUR identifiers collision identification response”. Moreover, the WUR Action frame comprises a WUR Parameters field 480 assigned according to the table 581.

According to embodiments of the invention, if WUR identifier modification information corresponds to a new value of a Transmit ID to be applied, the WUR Parameters field 480 comprises a subfield “Transmit ID” 584 corresponding to the value of the New Transmit ID to be applied.

According to embodiments of the invention, if WUR identifier modification information corresponds to a new value of a hash identifier to be applied, the WUR Parameters field 480 comprises a subfield “Hash Identifier” 584 corresponding to the value of the New Hash Identifier to be applied.

At step 1240, the AP sends the Broadcast PCR frame generated at step 1230 through the PCR module. It may be received by all non-AP stations of the BSS because they are all awake at the end of step 1220. Each non-AP station will decode the Broadcast PCR frame.

According to some embodiments of the invention, if the WUR identifier modification information corresponds to a new value of a Transmit ID to be applied, it will store directly the new received Transmit ID which be applied from now by AP (for instance for transmitting broadcast Wake-Up frames).

According to other embodiments of the invention, if the WUR identifier modification information corresponds to a new value of a hash identifier to be applied, it needs to recover the WUR identifiers hash function corresponding to the received hash identifier and computes the new Transmit ID to be applied from the BSSID and the recovered WUR identifiers hash function.

The above example also applies in the case of a Group ID collision. The person skilled in the art can easily adapt the above description to this case.

According to a second embodiment shown in Figure 12b, the AP sends the WUR identifier modification information separately through the PCR and WUR modules.

A key advantage of this second embodiment is that the multicast update information is received by all stations regardless of their states. In particular, it is not necessary for a given non-AP station to wait for its Wake-Up for receiving the multicast update information. In other words, in case a non-AP station is in doze mode while receiving the update information, it will process it when it will Wake-Up. A further exchange of messages is not necessary once the non-AP station is awake.

Steps 1201, 1205, 1230 and 1290 are the same as in the first embodiment of Figure 12a.

After step 1205, the AP generates a broadcast WUR frame at step 1260 that includes the WUR identifier modification information.

In a first example, the broadcast WUR frame corresponds to a WUR beacon frame with a dedicated 1 -bit field included in the Frame Control field 310 to indicate that the beacon frame also comprises a WUR identifier modification information. More specifically, the dedicated 1-bit field may be included in the Reserved field 315 of the Frame Control field 310. According to a first implementation, the WUR identifier modification information may be comprised in the Reserved field 315 of the Frame Control field 310. According to a second implementation, the WUR identifier modification information may be comprised in the payload field 340 of the WUR beacon frame.

In a second example, the broadcast WUR frame corresponds to a new type of WUR frame. More precisely, the Type subfield 311 of its Frame control field 310 is assigned according to the table 512 and is set to value 4 corresponding to a “WUR Broadcast Identifiers modification”. Moreover, its Address field 320 is set to its current Transmit ID. One should note that the Address field 320 is not set to the Transmit ID determined at step 1205. The WUR identifier modification information is comprised in the payload field 340 of the broadcast WUR frame.

At step 1270, the AP sends the broadcast WUR frame generated at step 1260 through the WUR module. This broadcast WUR frame (and consequently the broadcast update information) may be received by all non-AP stations in doze mode and ignored by the others excepted by non-AP station which WUR module is always ON.

Next, the steps 1230 and 1240 of Figure 12a are performed.

The order of the steps can be different. For example, the order of steps may be the following: step 1205, 1230, step 1240, step 1260 and next step 1270.

Moreover, in case of the WUR module of the non-AP station is always ON, steps 1230 and 1240 may not be implemented.

Figure 13 illustrates, using a flowchart, steps of a communication method during which a WUR identifier modification is signaled by an AP to a given non-AP station according to embodiments of the invention. In these embodiments, a new value of the Wake-Up ID is required by the non-AP station.

At a first step 1301, the AP receives a frame from a non-AP station (hereafter referred to as the targeted non-AP station) indicating that a collision occurred. This frame is sent by the non-AP station at step 740 of Figure 7.

In another embodiment of the invention, the algorithm here described may be launched when the AP receives an unexpected PCR frame. Such a case may occur when a non-AP station receives a Wake-Up WUR frame and processes it by error. For instance, it may happen when the Wake-Up WUR frame comprises some erroneous bits and nevertheless, its address field (read at step 610 of Figure 6) corresponds to the Transmit ID or Group ID in which the non-AP station is registered, or the Wake-Up ID of the non

AP station and the received FCS corresponds to the computed FCS (output of step 640 is yes).

At step 1305, the AP determines the WUR identifier modification information. In this example, the WUR identifier modification information is directly a new value of the Wake-Up ID. For instance, this new value can be selected randomly among a value range between 1 and 2047 excluding the Wake-Up ID of the non-AP stations already assigned by the AP and the Transmit ID of the AP.

Next, at step 1310, the AP determines the state of the targeted non-AP station: either in doze mode or awake.

If the targeted non-AP station is awake (output of 1320 is yes), the next step is 1350. If not, the next step is 1330.

At step 1330, the AP generates a unicast WUR frame including the WUR identifier modification information. The unicast WUR frame corresponds to a new type of WUR frame. More precisely the Type subfield 311 of its Frame control field 310 may be assigned according to the table 512 and may be set to value 5 corresponding to a “WUR Unicast Identifiers modification”. Moreover, its Address field 320 may be set to its current Wake-Up ID and not the Wake-Up ID determined at step 1305. The WUR identifier modification information may be comprised in the payload field 340 of the unicast WUR frame.

At next step 1340, the AP sends the generated unicast WUR frame through the WUR module and this frame may be received by the targeted non-AP station because its WUR is ON.

At step 1350, the AP generates a unicast PCR frame including the WUR identifier modification information. To do so, the AP generates a WUR Action frame as described with reference to Figure 4. Its Action Type field 476 may be assigned according to the table 577 described with reference to Figure 5 and may be set to 10 corresponding to “WUR identifiers collision identification”. Moreover, the WUR Action frame may comprise a WUR Parameters field 480 assigned according to the table 581. According to embodiments of the invention, if WUR identifier modification information corresponds to a new value of a Wake-Up ID to be applied, the WUR Parameters field 480 may comprise a subfield “Wake-Up ID” 586 corresponding to the value of the Wake-Up ID to be applied.

At next step 1360, the AP sends the generated unicast PCR frame through the PCR which may be received by the targeted non-AP station because its PCR is ON.

In the case of the WUR module of the non-AP station is always ON, only the steps 1330 may be implemented.

Although the present invention has been described hereinabove with reference to specific embodiments, the present invention is not limited to the specific embodiments, and modifications will be apparent to a skilled person in the art which lie within the scope of the present invention.

Many further modifications and variations will suggest themselves to those versed in the art upon making reference to the foregoing illustrative embodiments, which are given by way of example only and which are not intended to limit the scope of the invention, that being determined solely by the appended claims. In particular the different features from different embodiments may be interchanged, where appropriate.

In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be advantageously used.

Claims

1. A communication method in a wireless communication network comprising a plurality of network cells (BSS), each cell comprising at least one station (non-AP) managed by an access point (AP), the method comprising, at a station:

2. A method according to claim 1, wherein determining whether the WUR frame is for the attention of the station comprises determining whether the WUR identifier identifies the station, a group of stations to which the station belongs, or the access point managing the network cell of the station.

3. A method according to any one of the preceding claims, wherein the received WUR frame includes a frame check sequence (FCS) and wherein determining whether the WUR frame is for the attention of the station comprises a FCS test comprising:

4. A method according to claim 3, wherein the FCS is computed as the concatenation of the identifier of the network cell with at least one field of the WUR frame.

5. A method according to claim 3, wherein computing the FCS comprises applying a hash function to at least part of the identifier of the network cell.

6. A method according to any one of the preceding claims, comprising incrementing a counter each time it is determined that the WUR frame is not for the attention of the station, wherein transmitting said message is performed when the counter reaches a predetermined threshold.

7. A method according to any one of the preceding claims, wherein said message also depends on the type of the WUR identifier comprised in the WUR frame.

8. A method according to any one of the preceding claims, wherein determining whether the WUR frame is for the attention of the station comprises:

retrieving a registered WUR frame previously received by the station;

performing a bitwise comparison between the received WUR frame and the registered frame; and if some bits differ between the received WUR frame and the registered frame, performing the FCS test according to claim 3.

9. A method according to any one of the preceding claims, further comprising, in case of said negative determination, waking up a primary channel radio (PCR) module of the station and transmitting a message is performed by the PCR.

10. A method according to any one of the preceding claims, wherein the received WUR frame is a WUR beacon and the method further comprises updating WUR parameters of the station.

11. A method according to any one of the preceding claims, wherein determining whether the WUR frame is for the attention of the station comprises determining whether the WUR identifier is a Wake-Up ID identifying the station, a Group ID identifying a group of stations to which the station belongs, or a Transmit ID identifying the access point managing the network cell of the station.

12. A method according to any one of the preceding claims, wherein the message is an Action Frame with a field Action Type indicating that a collision occurred.

13. A method according to claim 12, wherein the message is an Action Frame with a field Action Type indicating that a collision occurred between Wake-Up ID identifiers, Group ID identifiers or Transmit ID identifiers.

14. A communication method in a wireless communication network comprising a plurality of network cells, each cell comprising at least one station (nonAP) managed by an access point (AP), the method comprising, at the access point:

15. A method according to claim 14, wherein transmitting a second message comprises transmitting a Wake-Up broadcast frame designed to wake up all the stations of the network cell of the access point that are in doze mode, wherein the second message is a primary channel radio (PCR) broadcast frame including said WUR identifier modification information, the PCR broadcast frame being transmitted to all the stations of the network cell of the access point.

16. A method according to claim 14, wherein transmitting a second message comprises:

transmitting a WUR broadcast frame including said WUR identifier modification information to all the stations of the network cell of the access point that are in doze mode; and transmitting a PCR broadcast frame including said WUR identifier modification information to all the stations of the network cell of the access point that are awake.

17. A method according to claim 14, wherein transmitting a second message to at least one station comprises:

18. A method according to any one of claims 14 to 17, wherein said WUR identifier modification information is a new WUR identifier.

19. A method according to any one of claims 14 to 17, wherein said WUR identifier modification information is an identifier of a hash function to be applied to compute a frame check sequence (FCS) of a WUR frame.

20. A method according to any one of claims 14 to 19, wherein the first message is an Action Frame with a field Action Type indicating that a collision occurred.

21. A method according to claim 20, wherein the first message is an Action Frame with a field Action Type indicating that a collision occurred between Wake-Up ID identifiers, Group ID identifiers or Transmit ID identifiers.

22. A method according to any one of claims 14 to 21, wherein the second message is an Action Frame with a field WUR Parameters indicating a new Wake-Up ID, a new Group-ID or a new Transmit ID to apply.

23. A method according to any one of claims 14 to 21, wherein the second message is an Action Frame with a field WUR Parameters indicating a hash identifier.

24. A non-transitory computer-readable medium storing a program which, when executed by a microprocessor or computer system in a device, causes the device to perform the method of claim 1 or 14.

25. A communication device station in a wireless communication network comprising a plurality of network cells (BSS), each cell comprising at least one station (non-AP) managed by an access point (AP), the communication device station comprising at least one microprocessor configured for carrying out the following steps:

receiving a Wake-Up Radio (WUR) frame comprising a WUR identifier; determining whether the WUR frame is for the attention of the station;

depending on said determining, transmitting a message indicating that the WUR identifier identifies several stations belonging to several network cells of the wireless communication network.

26. An access point (AP) in a wireless communication network comprising a plurality of network cells (BSS), each cell comprising at least one station (non-AP) managed by an access point (AP), the access point comprising at least one microprocessor configured for carrying out the following steps:

27. A wireless communication network comprising a plurality of network cells (BSS), each cell comprising at least one communication device station according to claim 25 and an access point according to claim 26.

28. A Wake-Up Radio (WUR) frame designed to be sent by a communication device station to an access point in a wireless communication network comprising a plurality of network cells (BSS), each cell comprising at least one station (non-AP) managed by an access point (AP), the WUR frame indicating a WUR identifier that identifies several stations belonging to several network cells of the wireless communication network.

29. A Wake-Up Radio (WUR) frame according to claim 28, further comprising an identifier of a hash function to be applied to compute a frame check sequence (FCS) based on the WUR frame.

30. A Wake-Up Radio (WUR) frame according to claim 28 or 29, comprising a field Action Type indicating that a collision occurred.

31. A Wake-Up Radio (WUR) frame according to any one of claim 28 to

30, comprising a field Action Type indicating that a collision occurred between WakeUp ID identifiers, Group ID identifiers or Transmit ID identifiers.

32. A Wake-Up Radio (WUR) frame according to any one of claim 28 to

31, comprising a field WUR Parameters indicating a new Wake-Up ID, a new Group-ID or a new Transmit ID to apply.

33. A Wake-Up Radio (WUR) frame according to any one of claim 28 to

32, comprising a field WUR Parameters indicating a hash identifier.

Intellectual

Property

Office

Application No:

GB 1807407.0

Examiner: Mrs Hannah Sylvester

Claims searched:

1-33

Date of search: 17 October 2018

Patents Act 1977: Search Report under Section 17

Documents considered to be relevant:

Category Relevant to claims Identity of document and passage or figure of particular relevance A - WO2018/076988 Al (HUAWEI TECHNOLOGIES CO. LTD) see paragraphs 55, 116, 124 and 125 at least A,E - WO2018/085635 Al (INTERDIGITAL PATENT HOLDINGS INC) see paragraphs 92, 94 and 101 A - WO2018/050087 Al (HUAWEI TECHNOLOGIES CO LTD) A - WO2018/076356 Al (HUAWEI TECHNOLOGIES CO LTD) see paragraph 28 A - US2015/245290 Al (HUAWEI TECHNOLOGIES CO. LTD)

Categories:

X Document indicating lack of novelty or inventive step A Document indicating technological background and/or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of before the filing date of this invention. same category. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.

Field of Search:

Search of GB, EP, WO & US patent documents classified in the following areas of the UKCX :

Worldw ide search of patent documents classified in the following areas of the IPC____________

H04W

The follow ing online and other databases have been used in the preparation of this search report

WPI EPODOC TXTE XP3GPP

International Classification:________________________________________________ Subclass Subgroup Valid From

None