WO2011087519A1

WO2011087519A1 - Handling high-priority calls in a td-scdma wireless communication system

Info

Publication number: WO2011087519A1
Application number: PCT/US2010/034142
Authority: WO
Inventors: Tom Chin; Guangming Shi; Kuo-Chun Lee
Original assignee: Qualcomm Incorporated
Priority date: 2010-01-15
Filing date: 2010-05-07
Publication date: 2011-07-21
Also published as: CN102204123A; TW201130342A; CN102204123B

Abstract

Emergency calls are handled in a TD-SCDMA system by a user equipment (UE) selecting an uplink synchronization code assigned for emergency calls and transmitting the uplink synchronization code to a Node B. The Node B, on receiving the synchronization code, will determine whether the code is assigned for handling emergency calls and, if so, will process the call from the UE according to an emergency priority.

Description

HANDLING HIGH-PRIORITY CALLS IN A TD-SCDMA WIRELESS COMMUNICATION SYSTEM

CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims the benefit of U.S. Provisional Patent Application No.

61/295,538, entitled "HANDLING HIGH-PRIORITY CALLS IN A TD-SCDMA WIRELESS COMMUNICATION SYSTEM," and filed on January 15, 2010, which is expressly incorporated by reference herein in its entirety.

BACKGROUND

Field

[0002] Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to handling high-priority calls in a time division- synchronous code division multiple access (TD-SCDMA) wireless communication system.

Background

[0003] Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the Universal Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3 GPP). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), and Time Division-Synchronous Code Division Multiple Access (TD- SCDMA). For example, China is pursuing TD-SCDMA as the underlying air interface in the UTRAN architecture with its existing GSM infrastructure as the core network. The UMTS also supports enhanced 3G data communications protocols, such as High Speed Downlink Packet Data (HSDPA), which provides higher data transfer speeds and capacity to associated UMTS networks. [0004] As the demand for mobile broadband access continues to increase, research and development continue to advance the UMTS technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications.

SUMMARY

[0005] In an aspect of the disclosure, emergency calls are handled in a time division- synchronous code division multiple access (TD-SCDMA) system by a user equipment (UE) selecting an uplink synchronization code assigned for emergency calls and transmitting the uplink synchronization code to a Node B.

[0006] In an aspect of the disclosure, a UE receives a system information message containing an access class (AC)-to-access service class (ASC) mapping table and a list of ASCs in the given cell. The UE uses the mapping table to determine an ASC that corresponds to its AC for an intended emergency call. The UE then selects the corresponding emergency-related ASC from the list of ASCs in the system information message received from the Node B with its assigned SYNC_UL code in the emergency code set. The UE transmits the SYNC_UL code associated with the emergency code set to the Node B and receives a priority acknowledgement from the Node B in response. The UE may then initiate its emergency call through the Node B by transmitting on the physical random access channel (PRACH).

[0007] In an aspect of the disclosure, when a UE having a current emergency call reaches a location that indicates a handover is needed to a next cell and a next Node B, the UE receives a handover message from the current Node B which includes a SYNC_UL code bitmap that designates the corresponding emergency SYNC_UL codes for the new cell. The UE transmits the new emergency SYNC_UL code to the new Node B in its uplink pilot time slot (UpPTS). The UE receives an emergency acknowledgement from the new Node B acknowledging the emergency priority and begins to transmit on the dedicated physical channel (DPCH) in the handover to continue its emergency call.

[0008] In an aspect of the disclosure, the Node B transmits a system information message containing at least an AC-to-ASC mapping table and a list of ASCs available in its cell. The Node B receives UpPTS time frames from each UE attempting to initiate access to the cell, in which each UpPTS time frame includes a SYNC UL code. The Node B determines whether any of the SYNC UL codes correspond to codes in the emergency code set. If so, then the Node B transmits a priority acknowledgement to the UE from which the emergency SYNC_UL code was received. If not, then the Node B processes the non-emergency calls according to the normal processing routines subject to processing of any priority emergency calls.

[0009] In an aspect of the disclosure, the Node B detects that a UE placing an emergency call has reached a location requiring a handover to a next cell and a next Node B. The current Node B generates a handover message that includes a SYNC_UL code bitmap indicating the SYNC UL codes reserved for emergency calls in the emergency code set of the new cell. The current Node B transmits the handover message to the UE placing the emergency call.

[0010] In another aspect of the disclosure, a UE of a TD-SCDMA includes at least one processor configured to select an uplink synchronization code assigned for emergency calls and transmit the uplink synchronization code. The UE also includes a memory coupled to the processor.

[0011] In another aspect of the disclosure, a computer program product includes a computer readable medium with program code recorded thereon. The program code includes code to select an uplink synchronization code assigned for emergency calls and code to transmit the uplink synchronization code.

[0012] In another aspect of the disclosure, a UE configured for wireless communication in a TD-SCDMA system includes means for selecting an uplink synchronization code assigned for emergency calls and means for transmitting the uplink synchronization code.

[0013] In another aspect of the disclosure, a method of wireless communication in a

TD-SCDMA system includes receiving a synchronization code from a UE, determining whether the synchronization code is assigned for emergency calls, and in response to the synchronization code being assigned for emergency calls, processing transmissions from the UE according to an emergency priority.

[0014] In another aspect of the disclosure, a Node B configured for wireless communication in a TD-SCDMA system includes means for receiving a synchronization code from a UE, means for determining whether the synchronization code is assigned for emergency calls, and means, executable in response to the synchronization code being assigned for emergency calls, for processing transmissions from the UE according to an emergency priority.

[0015] In another aspect of the disclosure, a Node B of a TD-SCDMA system includes at least one processor configured to determine whether a synchronization code received from a UE is assigned for emergency calls and, in response to the synchronization code being assigned only for emergency calls, process transmissions from the UE according to an emergency priority. The Node B also includes a memory coupled to the processor.

[0016] In another aspect of the disclosure, a computer program product includes a computer readable medium with program code recorded thereon. The program code includes code to receive a synchronization code from a UE, code to determine whether the synchronization code is assigned for emergency calls, and code, executable in response to the synchronization code being assigned for emergency calls, to process transmissions from the UE according to an emergency priority.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a block diagram conceptually illustrating an example of a telecommunications system.

[0018] FIG. 2 is a block diagram conceptually illustrating an example of a frame structure in a telecommunications system.

[0019] FIG. 3 is a block diagram conceptually illustrating an example of a Node B in communication with a UE in a telecommunications system.

[0020] FIG. 4 is a functional block diagram illustrating example blocks executed in conducting wireless communication according to one aspect of the present disclosure.

[0021] FIG. 5A is a functional block diagram illustrating example blocks executed by a

UE in conducting wireless communication according to one aspect of the present disclosure.

[0022] FIG. 5B is a functional block diagram illustrating example blocks executed by a

[0023] FIG. 6A is a functional block diagram illustrating example blocks executed by a

Node B in conducting wireless communication according to one aspect of the present disclosure. [0024] FIG. 6B is a functional block diagram illustrating example blocks executed by a

Node B in conducting wireless communication according to one aspect of the present disclosure.

[0025] FIG. 7 is a block diagram illustrating a cell of a telecommunications network configured according to one aspect of the present disclosure.

DETAILED DESCRIPTION

[0026] The detailed description set forth below, in connection with the appended drawings, is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

[0027] Turning now to FIG. 1, a block diagram is shown illustrating an example of a telecommunications system 100. The various concepts presented throughout this disclosure may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards. By way of example and without limitation, the aspects of the present disclosure illustrated in FIG. 1 are presented with reference to a UMTS system employing a TD-SCDMA standard. In this example, the UMTS system includes a (radio access network) RAN 102 (e.g., UTRAN) that provides various wireless services including telephony, video, data, messaging, broadcasts, and/or other services. The RAN 102 may be divided into a number of Radio Network Subsystems (RNSs) such as an RNS 107, each controlled by a Radio Network Controller (RNC) such as an RNC 106. For clarity, only the RNC 106 and the RNS 107 are shown; however, the RAN 102 may include any number of RNCs and RNSs in addition to the RNC 106 and RNS 107. The RNC 106 is an apparatus responsible for, among other things, assigning, reconfiguring and releasing radio resources within the RNS 107. The RNC 106 may be interconnected to other RNCs (not shown) in the RAN 102 through various types of interfaces such as a direct physical connection, a virtual network, or the like, using any suitable transport network. [0028] The geographic region covered by the RNS 107 may be divided into a number of cells, with a radio transceiver apparatus serving each cell. A radio transceiver apparatus is commonly referred to as a Node B in UMTS applications, but may also be referred to by those skilled in the art as a base station (BS), a base transceiver station (BTS), a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), or some other suitable terminology. For clarity, two Node Bs 108 are shown; however, the RNS 107 may include any number of wireless Node Bs. The Node Bs 108 provide wireless access points to a core network 104 for any number of mobile apparatuses. Examples of a mobile apparatus include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a notebook, a netbook, a smartbook, a personal digital assistant (PDA), a satellite radio, a global positioning system (GPS) device, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, or any other similar functioning device. The mobile apparatus is commonly referred to as user equipment (UE) in UMTS applications, but may also be referred to by those skilled in the art as a mobile station (MS), a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal (AT), a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. For illustrative purposes, three UEs 110 are shown in communication with the Node Bs 108. The downlink (DL), also called the forward link, refers to the communication link from a Node B to a UE, and the uplink (UL), also called the reverse link, refers to the communication link from a UE to a Node B.

[0029] The core network 104, as shown, includes a GSM core network. However, as those skilled in the art will recognize, the various concepts presented throughout this disclosure may be implemented in a RAN, or other suitable access network, to provide UEs with access to types of core networks other than GSM networks.

[0030] In this example, the core network 104 supports circuit-switched services with a mobile switching center (MSC) 112 and a gateway MSC (GMSC) 114. One or more RNCs, such as the RNC 106, may be connected to the MSC 112. The MSC 112 is an apparatus that controls call setup, call routing, and UE mobility functions. The MSC 112 also includes a visitor location register (VLR) (not shown) that contains subscriber- related information for the duration that a UE is in the coverage area of the MSC 112. The GMSC 114 provides a gateway through the MSC 112 for the UE to access a circuit- switched network 116. The GMSC 114 includes a home location register (HLR) (not shown) containing subscriber data, such as the data reflecting the details of the services to which a particular user has subscribed. The HLR is also associated with an authentication center (AuC) that contains subscriber-specific authentication data. When a call is received for a particular UE, the GMSC 114 queries the HLR to determine the UE's location and forwards the call to the particular MSC serving that location.

[0031] The core network 104 also supports packet-data services with a serving GPRS support node (SGSN) 118 and a gateway GPRS support node (GGSN) 120. GPRS, which stands for General Packet Radio Service, is designed to provide packet-data services at speeds higher than those available with standard GSM circuit-switched data services. The GGSN 120 provides a connection for the RAN 102 to a packet-based network 122. The packet-based network 122 may be the Internet, a private data network, or some other suitable packet-based network. The primary function of the GGSN 120 is to provide the UEs 110 with packet-based network connectivity. Data packets are transferred between the GGSN 120 and the UEs 110 through the SGSN 118, which performs primarily the same functions in the packet-based domain as the MSC 112 performs in the circuit- switched domain.

[0032] The UMTS air interface is a spread spectrum Direct- Sequence Code Division

Multiple Access (DS-CDMA) system. The spread spectrum DS-CDMA spreads user data over a much wider bandwidth through multiplication by a sequence of pseudorandom bits called chips. The TD-SCDMA standard is based on such direct sequence spread spectrum technology and additionally calls for a time division duplexing (TDD), rather than a frequency division duplexing (FDD) as used in many FDD mode UMTS/W-CDMA systems. TDD uses the same carrier frequency for both the uplink (UL) and downlink (DL) between a Node B 108 and a UE 110, but divides uplink and downlink transmissions into different time slots in the carrier.

[0033] FIG. 2 shows a frame structure 200 for a TD-SCDMA carrier. The TD-SCDMA carrier, as illustrated, has a frame 202 that is 10 ms in length. The frame 202 has two 5 ms subframes 204, and each of the subframes 204 includes seven time slots, TSO through TS6. The first time slot, TSO, is usually allocated for downlink communication, while the second time slot, TS1, is usually allocated for uplink communication. The remaining time slots, TS2 through TS6, may be used for either uplink or downlink, which allows for greater flexibility during times of higher data transmission times in either the uplink or downlink directions. Each time slot, TS0-TS6, may allow data transmission multiplexed on a maximum of 16 code channels. Data transmission on a code channel includes two data portions 212 separated by a midamble 214 and followed by a guard period (GP) 216. The midamble 214 may be used for features, such as channel estimation, while the GP 216 may be used to avoid inter-burst interference.

[0034] A downlink pilot time slot (DwPTS) 206, a guard period (GP) 208, and an uplink pilot time slot (UpPTS) 210 (also known as the uplink pilot channel (UpPCH)) are located between TS0 and TS1. The DwPTS 206 is used for transmitting the pilot signal for the cell, while the UpPTS 210 can be used for the UEs to perform initial random access, when first attempting access to the particular cell, or uplink synchronization in a handover process.

[0035] FIG. 3 is a block diagram of a Node B 310 in communication with a UE 350 in a

RAN 300, where the RAN 300 may be the RAN 102 in FIG. 1, the Node B 310 may be the Node B 108 in FIG. 1, and the UE 350 may be the UE 110 in FIG. 1. In the downlink communication, a transmit processor 320 may receive data from a data source 312 and control signals from a controller/processor 340. The transmit processor 320 provides various signal processing functions for the data and control signals, as well as reference signals (e.g., pilot signals). For example, the transmit processor 320 may provide cyclic redundancy check (CRC) codes for error detection, coding and interleaving to facilitate forward error correction (FEC), mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M- quadrature amplitude modulation (M-QAM), and the like), spreading with orthogonal variable spreading factors (OVSF), and multiplying with scrambling codes to produce a series of symbols. Channel estimates from a channel processor 344 may be used by a controller/processor 340 to determine the coding, modulation, spreading, and/or scrambling schemes for the transmit processor 320. These channel estimates may be derived from a reference signal transmitted by the UE 350 or from feedback contained in the midamble 214 (FIG. 2) from the UE 350. The symbols generated by the transmit processor 320 are provided to a transmit frame processor 330 to create a frame structure. The transmit frame processor 330 creates this frame structure by multiplexing the symbols with a midamble 214 (FIG. 2) from the controller/processor 340, resulting in a series of frames. The frames are then provided to a transmitter 332, which provides various signal conditioning functions including amplifying, filtering, and modulating the frames onto a carrier for downlink transmission over the wireless medium through smart antennas 334. The smart antennas 334 may be implemented with beam steering bidirectional adaptive antenna arrays or other similar beam technologies.

[0036] At the UE 350, a receiver 354 receives the downlink transmission through an antenna 352 and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver 354 is provided to a receive frame processor 360, which parses each frame, and provides the midamble 214 (FIG. 2) to a channel processor 394 and the data, control, and reference signals to a receive processor 370. The receive processor 370 then performs the inverse of the processing performed by the transmit processor 320 in the Node B 310. More specifically, the receive processor 370 descrambles and despreads the symbols, and then determines the most likely signal constellation points transmitted by the Node B 310 based on the modulation scheme. These soft decisions may be based on channel estimates computed by the channel processor 394. The soft decisions are then decoded and deinterleaved to recover the data, control, and reference signals. The CRC codes are then checked to determine whether the frames were successfully decoded. The data carried by the successfully decoded frames will then be provided to a data sink 372, which represents applications running in the UE 350 and/or various user interfaces (e.g., display). Control signals carried by successfully decoded frames will be provided to a controller/processor 390. When frames are unsuccessfully decoded by the receiver processor 370, the controller/processor 390 may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.

[0037] In the uplink, data from a data source 378 and control signals from the controller/processor 390 are provided to a transmit processor 380. The data source 378 may represent applications running in the UE 350 and various user interfaces (e.g., keyboard). Similar to the functionality described in connection with the downlink transmission by the Node B 310, the transmit processor 380 provides various signal processing functions including CRC codes, coding and interleaving to facilitate FEC, mapping to signal constellations, spreading with OVSFs, and scrambling to produce a series of symbols. Channel estimates, derived by the channel processor 394 from a reference signal transmitted by the Node B 310 or from feedback contained in the midamble transmitted by the Node B 310, may be used to select the appropriate coding, modulation, spreading, and/or scrambling schemes. The symbols produced by the transmit processor 380 will be provided to a transmit frame processor 382 to create a frame structure. The transmit frame processor 382 creates this frame structure by multiplexing the symbols with a midamble 214 (FIG. 2) from the controller/processor 390, resulting in a series of frames. The frames are then provided to a transmitter 356, which provides various signal conditioning functions including amplification, filtering, and modulating the frames onto a carrier for uplink transmission over the wireless medium through the antenna 352.

[0038] The uplink transmission is processed at the Node B 310 in a manner similar to that described in connection with the receiver function at the UE 350. A receiver 335 receives the uplink transmission through the antenna 334 and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver 335 is provided to a receive frame processor 336, which parses each frame, and provides the midamble 214 (FIG. 2) to the channel processor 344 and the data, control, and reference signals to a receive processor 338. The receive processor 338 performs the inverse of the processing performed by the transmit processor 380 in the UE 350. The data and control signals carried by the successfully decoded frames may then be provided to a data sink 339 and the controller/processor 340, respectively. If some of the frames were unsuccessfully decoded by the receive processor, the controller/processor 340 may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.

[0039] The controller/processors 340 and 390 may be used to direct the operation at the

Node B 310 and the UE 350, respectively. For example, the controller/processors 340 and 390 may provide various functions including timing, peripheral interfaces, voltage regulation, power management, and other control functions. The computer readable media of memories 342 and 392 may store data and software for the Node B 310 and the UE 350, respectively. A scheduler/processor 346 at the Node B 310 may be used to allocate resources to the UEs and schedule downlink and/or uplink transmissions for the UEs. [0040] One of the important features in TD-SCDMA systems is uplink synchronization.

In TD-SCDMA systems, different UEs synchronize on the uplink so that the transmitted signals from all of these different UEs arrive ideally at the Node B at the same time. The UpPTS 210 (FIG. 2) is defined for this purpose. The UE transmits a SYNC UL code in the UpPTS 210 for initial access or handover process. The Node B receives this SYNC UL code, measures the timing, and sends any corrections commands using an acknowledgement (ACK) message on the fast physical access channel (FPACH). If the UE detects the appropriate codes with the ACK, it can then either begin transmitting on the physical random access channel (PRACH) in an initial random access procedure or begin transmitting on the dedicated physical channel (DPCH) in a handoff procedure.

[0041] For each cell, there are eight available SYNC UL codes. The Node B provides a list of available SYNC UL codes in system information messages broadcast to the cell. UEs receiving the system information messages discover the available SYNC_UL codes and select one for transmission in the UpPTS 210 (FIG. 2).

[0042] In some instances, a UE, such as UE 350, may attempt to place an emergency call in the wireless communication system in which the RAN 300 resides. In the United States, an emergency call may be designated by a 9-1-1 call from the UE. Other countries may have additional ways to designate an emergency call. In operation, it would be beneficial to give priority to emergency calls in various call processing functions within the network, such as call initiation and call handoff. However, as currently defined, there are no ways to differentiate emergency calls from regular calls in TD-SCDMA systems.

[0043] FIG. 4 is a functional block diagram 40 illustrating example blocks executed in conducting wireless communication according to one aspect of the present disclosure. In block 400, a subset of the available SYNC UL codes for each cell are classified into an emergency code set. The system provider will usually designate which of the available SYNC_UL codes will be assigned for the emergency code set. This information would be entered into the system and transmitted to each of the Node Bs through the RNCs of the wireless system. Node Bs will then transmit system information messages, in block 401, identifying available SYNC UL codes for the emergency code set and available SYNC UL codes for other calls. UEs within the cell receive the system information messages, in block 402, and select the appropriate SYNC UL code associated with the type of call intended to be made. In block 403, the UEs transmit the selected SYNC UL code in their respective UpPTS. The Node Bs receive the UpPTS transmissions in block 404. A determination is made, in block 405, whether the SYNC UL code within each of the UpPTS transmissions corresponds to the emergency code set. If so, then, in block 406, priority processing is given to the calls originating from the UEs transmitting SYNC UL codes corresponding to the emergency code set. Otherwise, in block 407, calls originating from the UEs without SYNC UL codes in the emergency code set will be afforded normal processing at a priority lower than that given the emergency code set. In block 408, UEs with on-going emergency calls reach a position in the cell for hand off to a next Node B. The Node Bs currently handling the emergency calls for the UEs entering a hand off location generate a hand off message, in block 409, such as a PHYSICAL CHANNEL RECONFIGURATION message, which provides a SYNC UL code bitmap assigning a SYNC UL code from the new cell categorized in the emergency code set for the new cell. In block 410, the UEs handing over an emergency call receive the hand off message from its associated current Node B and select the new SYNC UL code from the emergency code set of the new cell. The UEs handing over an emergency call then transmit, in block 411, the new SYNC UL code in its UpPTS to the next Node Bs in the respective new cells. The new Node Bs make the determination, in block 405, whether the SYNC_UL codes received from the UEs entering the new cells are within the emergency code set. If so, in block 406, the new Node Bs provide priority call processing for the calls originating from the UEs with SYNC UL codes within the emergency code set. Otherwise, in block 407, normal processing is provided subject to calls with SYNC_UL codes within the emergency code set.

In GSM and certain other 3GPP-supported mobile communication systems, UEs are assigned to one of 16 access classes (ACs), with class 10 being assigned to emergency calls. Regular UEs are assigned to classes 0-9, while special UEs are assigned to classes 11-15. During specific periods, such as emergency periods or periods in which a particular Node B goes down, there may be an access class restriction that does not allow normal UEs, i.e., those assigned to access classes 0-9, to access the communication system to place a regular call. However, if one of these UEs attempts to place an emergency called assigned to access class 10, the system may allow such a call to access the restricted system, assuming access class 10 is also not restricted. While these GSM and other 3GGP-supported networks maintain this feature, the ability to prioritize based on access class is not carried over in TD-SCDMA systems even though TD-SCDMA UEs are still assigned to specific access classes.

[0045] The TD-SCDMA standards define up to eight access service classes (ASCs) that may have their own resource allocations. These eight access service classes may be associated with the eight available SYNC UL code indices for the given cell. Thus, UEs intending to place an emergency call may acquire the access service classes corresponding to the SYNC UL code indices found in the emergency code set through system information messages, such as the system information block-type 5 messages. These UEs may then obtain the appropriate emergency code set SYNC UL codes from the access service classes. However, the UEs know their own access class, but do not necessarily know which access service class of the Node B corresponds to their access class. To resolve this, an access class-to-access service class mapping table is generated and transmitted by the Node B in its system information messages, such as the system information block-type 5 messages. Therefore, when the UEs receive the system information message containing the access class-to-access service class mapping table, the UE will be able to select the particular access service class corresponding to its access class.

[0046] FIG. 5 A is a functional block diagram 50 illustrating example blocks executed by a UE in conducting wireless communication according to one aspect of the present disclosure. In block 500, the UE receives a system information message containing an access class-to-access service class mapping table and a list of access service classes in the given cell. The UE uses the mapping table, in block 501, to determine an access service class that corresponds to its access class for an intended emergency call. The UE then selects the corresponding emergency-related access service class, in block 502, from the list of access service classes in the system information message received from the Node B with its assigned SYNC_UL code in the emergency code set. The UE transmits the SYNC_UL code associated with the emergency code set to the Node B in block 503, and receives a priority acknowledgement from the Node B in response in block 504. The UE may then initiate its emergency call through the Node B, in block 505, by transmitting on the physical random access channel.

[0047] FIG. 5B is a functional block diagram 51 illustrating example blocks executed by a UE in conducting wireless communication according to one aspect of the present disclosure. If the UE of FIG. 5A reaches a location that indicates a handover is needed to a next cell and a next Node B, the UE receives a handover message, in block 506, from the current Node B which includes a SYNC UL code bitmap that designates the corresponding emergency SYNC UL codes for the new cell. In block 507, the UE transmits the new emergency SYNC_UL code to the new Node B in its UpPTS. The UE receives an emergency acknowledgement from the new Node B, in block 508, acknowledging the emergency priority and begins to transmit on the dedicated physical channel in the handover to continue its emergency call.

[0048] From the perspective of the Node B, the functionality for emergency priority revolves around the division of SYNC UL codes into an emergency code set and one or more sets for the remaining SYNC UL codes. FIG. 6A is a functional block diagram 60 illustrating example blocks executed by a Node B in conducting wireless communication according to one aspect of the present disclosure. In block 600, the Node B transmits a system information message containing at least an access class-to- access service class mapping table and a list of access service classes available in its cell. The Node B receives SYNC UL codes from each UE attempting to initiate access to the cell, in block 601, through the UpPTS time slots that include the SYNC UL codes. The Node B determines, in block 602, whether any of the SYNC UL codes correspond to codes in the emergency code set. If so, then, in block 603, the Node B transmits a priority acknowledgement to the UE from which the emergency SYNC UL code was received. If not, then, in block 604, the Node B processes the non-emergency calls according to the normal processing routines subject to processing of any priority emergency calls.

[0049] FIG. 6B is a functional block diagram 61 illustrating example blocks executed by a Node B in conducting wireless communication according to one aspect of the present disclosure. In block 605, the Node B detects that a UE placing an emergency call has reached a location requiring a handover to a next cell and a next Node B. The current Node B generates a handover message, in block 606, that includes a SYNC UL code bitmap indicating the SYNC UL codes reserved for emergency calls in the emergency code set of the new cell. In block 607, the Node B transmits the handover message to the UE placing the emergency call.

[0050] FIG. 7 is a block diagram illustrating a cell 70 of a telecommunications network configured according to one aspect of the present disclosure. A Node B 700 serves the cell 70. Two UEs 701-702 begin a random access process to connect calls through the Node B 700. The UE 702 is initiating a regular call and selects an available SYNC UL code associated with a regular call. The UE 701 is initiating an emergency call to 9-1-1 and selects an available SYNC_UL code that is assigned to an emergency synchronization code set. The UE 702 transmits its selected SYNC UL code in the UpPTS, while the UE 701 transmits its emergency SYNC UL code in the UpPTS. On receipt of the SYNC UL codes from the UEs 701-702, the Node B 700 checks each of the received SYNC UL codes to determine if either is a member of the emergency code set. In response to the Node B 700 determining that the SYNC UL code from the UE 701 belongs to the emergency code set, the Node B 700 designates the call from the UE 701 as a priority processing call and transmits a priority acknowledgement to the UE 701. The acknowledgement for the UE 702 is not transmitted by the Node B 700 until after processing the acknowledgement for the UE 701. Once the priority acknowledgement is received, the UE 701 may then begin transmitting on the physical random access channel to initiate the emergency call.

[0051] It should be noted that the number of SYNC UL codes be assigned to an emergency code set can be dynamic in various aspects of the present disclosure. For example, if a natural disaster is known to have hit a certain area, then additional SYNC UL codes may be added to the emergency code set allowing additional emergency calls to have priority handling, while, at the same time, restricting regular calls within the area.

[0052] Turning back to FIG. 3, in order to implement aspects of the present disclosure, the Node B 310 includes several modules and sets of data stored in memory 342, including a priority detection module 391, SYNC UL Code Sets 393, an access class- to-access service class mapping table 395, and an Access Service Class List 396. The SYNC_UL Code Sets 393 is the record of code sets, including the emergency code set of available SYNC_UL codes designated as emergency codes. The access class-to- access service class mapping table 395 provides mapping between a particular access class assignment and a corresponding access service class. The Access Service Class List 396 provides the list of access service classes and their associated SYNC_UL codes. When the Node B 310 prepares to transmit system information messages via the transmit processor 320 and, eventually, the transmitter 332, the controller/processor 340 retrieves the access class-to-access service class mapping table 395 and the Access Service Class List 396 for inclusion into the system information message. These resources will be used by the UEs receiving the system information message to select the appropriate access service class and associated SYNC UL code for its intended call purpose. As the Node B 310 receives SYNC_UL codes from the UEs, such as UE 350, the controller/processor 340 executes the priority detection module 391 to determine whether the received SYNC UL code is an emergency code or a regular code. The executing priority detection module 391 uses the SYNC UL Code Sets 393 to make this determination. If an emergency code is detected, the priority detection module 391 signals the controller/processor 340 to handle the call from the related UE in a priority process.

[0053] On the side of the UE 350, the UE 350 maintains in its memory 392, its own

Assigned Access Class 397 and an Emergency Call Designator 398. When setting up a standard call, the UE 350 uses the Assigned Access Class 397 to select the appropriate access service class and associated SYNC_UL code. If, however, an emergency call is set up, the UE 350 retrieves the Emergency Call Designator 398 to temporarily change the access class of the UE 350 to the class designated for emergency calls, e.g., access class 10. The UE 350 will then use this new emergency access class to select the appropriate emergency access service class and its associated emergency SYNC_UL code to transmit to the Node B 310 when establishing the emergency call.

[0054] In one configuration, the Node B 310 includes means for transmitting a system information message containing at least the available emergency SYNC UL codes and the available regular SYNC UL codes. In one aspect, the aforementioned means may be the controller/processor 340, the memory 342, the SYNC_UL Code Sets 393, access class-to- access service class mapping table 395, and/or the Access Service Class List 396, each stored in the memory 342, along with the transmit processor 320, the transmit frame processor 330, transmitter 332, and smart antennas 334, configured to perform the functions recited by the aforementioned means. In another aspect, the aforementioned means may be a module or any apparatus configured to perform the functions recited by the aforementioned means. The Node B 310 also includes means for receiving a SYNC UL code and determining whether that code is an emergency code. In one aspect, the aforementioned means may be the controller/processor 340, the memory 342, the priority detection module 391 stored in the memory 342, along with the smart antennas 334, the receiver 335, the receive frame processor 336, and the receive processor 338, configured to perform the functions recited by the aforementioned means. The Node B 310 also includes means for providing priority processing to calls having an emergency SYNC UL code. In one aspect, the aforementioned means may be the controller/processor 340, the memory 342, the priority detection module 391 stored in the memory 342, along with the scheduler/processor 346, the transmit processor 320, the transmit frame processor 330, transmitter 332, and smart antennas 334, configured to perform the functions recited by the aforementioned means.

[0055] In another configuration, the UE 350 includes means for selecting a SYNC UL assigned for emergency calls. In one aspect, the aforementioned means may be the smart antennas 352, the receiver 354, the receive frame processor 360, the receive processor 370, controller/processor 390, the memory 392, the emergency call designator 398 stored in the memory 392, along with the access class-to-access service class mapping table 395 received from the Node B 310, and the Access Service Class List 396 received from the Node B 310, configured to perform the functions recited by the aforementioned means. The UE 350 includes means for transmitting the selected SYNC UL code to the Node B 310. In one aspect, the aforementioned means may be the controller/processor 390, the transmit processor 380, the transmit frame processor 382, the transmitter 356, and the smart antennas 352, configured to perform the functions recited by the aforementioned means.

[0056] Several aspects of a telecommunications system has been presented with reference to a TD-SCDMA system. As those skilled in the art will readily appreciate, various aspects described throughout this disclosure may be extended to other telecommunication systems, network architectures and communication standards. By way of example, various aspects may be extended to other UMTS systems such as W- CDMA, High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), High Speed Packet Access Plus (HSPA+) and TD-CDMA. Various aspects may also be extended to systems employing Long Term Evolution (LTE) (in FDD, TDD, or both modes), LTE-Advanced (LTE-A) (in FDD, TDD, or both modes), CDMA2000, Evolution-Data Optimized (EV-DO), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Ultra- Wideband (UWB), Bluetooth, and/or other suitable systems. The actual telecommunication standard, network architecture, and/or communication standard employed will depend on the specific application and the overall design constraints imposed on the system. [0057] Several processors have been described in connection with various apparatuses and methods. These processors may be implemented using electronic hardware, computer software, or any combination thereof. Whether such processors are implemented as hardware or software will depend upon the particular application and overall design constraints imposed on the system. By way of example, a processor, any portion of a processor, or any combination of processors presented in this disclosure may be implemented with a microprocessor, microcontroller, digital signal processor (DSP), a field-programmable gate array (FPGA), a programmable logic device (PLD), a state machine, gated logic, discrete hardware circuits, and other suitable processing components configured to perform the various functions described throughout this disclosure. The functionality of a processor, any portion of a processor, or any combination of processors presented in this disclosure may be implemented with software being executed by a microprocessor, microcontroller, DSP, or other suitable platform.

[0058] Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside on a computer-readable medium. A computer-readable medium may include, by way of example, memory such as a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., compact disc (CD), digital versatile disc (DVD)), a smart card, a flash memory device (e.g., card, stick, key drive), random access memory (RAM), read only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), a register, or a removable disk. Although memory is shown separate from the processors in the various aspects presented throughout this disclosure, the memory may be internal to the processors (e.g., cache or register).

[0059] Computer-readable media may be embodied in a computer-program product. By way of example, a computer-program product may include a computer-readable medium in packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system.

[0060] It is to be understood that the specific order or hierarchy of steps in the methods disclosed is an illustration of exemplary processes. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the methods may be rearranged. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented unless specifically recited therein.

[0061] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more." Unless specifically stated otherwise, the term "some" refers to one or more. A phrase referring to "at least one of a list of items refers to any combination of those items, including single members. As an example, "at least one of: a, b, or c" is intended to cover: a; b; c; a and b; a and c; b and c; and a, b and c. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. § 112, sixth paragraph, unless the element is expressly recited using the phrase "means for" or, in the case of a method claim, the element is recited using the phrase "step for."

[0062] WHAT IS CLAIMED IS:

Claims

20 CLAIMS

1. A method of wireless communication in a time division-synchronous code division multiple access (TD-SCDMA) system, said method comprising:

selecting an uplink synchronization code assigned for emergency calls; and transmitting said uplink synchronization code.

2. The method of claim 1 wherein said uplink synchronization code is transmitted during an initial access to said TD-SCDMA system.

3. The method of claim 1 wherein said uplink synchronization code is transmitted during a hand over between a first cell of said TD-SCDMA system and a second cell of said TD-SCDMA system.

4. A user equipment (UE) of a time division-synchronous code division multiple access (TD-SCDMA) system, said UE comprising:

at least one processor configured to:

select an uplink synchronization code assigned for emergency calls; and transmit said uplink synchronization code; and

a memory coupled to said at least one processor.

5. The UE of claim 4 wherein said uplink synchronization code is transmitted during an initial access to said TD-SCDMA system.

6. The UE of claim 4 wherein said uplink synchronization code is transmitted during a hand over between a first cell of said TD-SCDMA system and a second cell of said TD-SCDMA system.

7. A computer program product comprising:

a computer readable medium with program code recorded thereon, said program code comprising:

program code to select an uplink synchronization code assigned for 21 emergency calls; and

program code to transmit said uplink synchronization code.

8. The computer program product of claim 7 wherein said program code to transmit transmits said uplink synchronization code during an initial access to said TD- SCDMA system.

9. The computer program product of claim 7 wherein said program code to transmit transmits said uplink synchronization code during a hand over between a first cell of said TD-SCDMA system and a second cell of said TD-SCDMA system.

10. A user equipment (UE) configured for wireless communication in a time division-synchronous code division multiple access (TD-SCDMA) system, said UE comprising:

means for selecting an uplink synchronization code assigned for emergency calls; and

means for transmitting said uplink synchronization code.

11. The UE of claim 10 wherein said means for transmitting transmits said uplink synchronization code during an initial access to said TD-SCDMA system.

12. The UE of claim 10 wherein said means for transmitting transmits said uplink synchronization code during a hand over between a first cell of said TD-SCDMA system and a second cell of said TD-SCDMA system.

13. A method of wireless communication in a time division-synchronous code division multiple access (TD-SCDMA) system, said method comprising:

receiving a synchronization code from a user equipment (UE);

determining whether said synchronization code is assigned for emergency calls; and

in response to said synchronization code being assigned for emergency calls, processing transmissions from said UE according to an emergency priority. 22

14. The method of claim 13 wherein said synchronization code is received from said UE during initial access of said UE to said TD-SCDMA system.

15. The method of claim 13 wherein said synchronization code is received from said UE during a hand over between a first cell of said TD-SCDMA system and a second cell of said TD-SCDMA system.

16. A Node B configured for wireless communication in a time division- synchronous code division multiple access (TD-SCDMA) system, said Node B comprising:

means for receiving a synchronization code from a user equipment (UE);

means for determining whether said synchronization code is assigned for emergency calls; and

means, executable in response to said synchronization code being assigned for emergency calls, for processing transmissions from said UE according to an emergency priority.

17. The Node B of claim 16 wherein said synchronization code is received from said UE during initial access of said UE to said TD-SCDMA system.

18. The Node B of claim 16 wherein said synchronization code is received from said UE during a hand over between a first cell of said TD-SCDMA system and said Node B.

19. A Node B of a time division-synchronous code division multiple access (TD-SCDMA) system, said Node B comprising:

at least one processor configured to:

determine whether a synchronization code received from a user equipment (UE) is assigned for emergency calls; and

in response to said synchronization code being assigned for emergency calls, process transmissions from said UE according to an emergency priority; and a memory coupled to said at least one processor.

20. The Node B of claim 19 wherein said synchronization code is received from said UE during initial access of said UE to said TD-SCDMA system.

21. The Node B of claim 19 wherein said synchronization code is received from said UE during a hand over between a first cell of said TD-SCDMA system and said Node B.

22. A computer program product comprising:

program code to receive a synchronization code from a user equipment (UE) of a time division-synchronous code division multiple access (TD-SCDMA) system;

program code to determine whether said synchronization code is assigned for emergency calls; and

program code, executable in response to said synchronization code being assigned for emergency calls, to process transmissions from said UE according to an emergency priority.

23. The computer program product of claim 22 wherein said synchronization code is received from said UE during initial access of said UE to said TD-SCDMA system.

24. The computer program product of claim 22 wherein said synchronization code is received from said UE during a hand over between a first cell of said TD- SCDMA system and a second cell of said TD-SCDMA system.