WO2015139298A1

WO2015139298A1 - Security mode updates during cellular relocation to avoid call drop

Info

Publication number: WO2015139298A1
Application number: PCT/CN2014/073848
Authority: WO
Inventors: Xuepan GUAN; Huan Xu; Jie Mao; Tim Tynghuei Liou; Shiau-He Tsai
Original assignee: Qualcomm Incorporated
Priority date: 2014-03-21
Filing date: 2014-03-21
Publication date: 2015-09-24

Abstract

An undesired call drop in a UMTS network can be avoided during a relocation procedure when a UE fails to receive a certain acknowledgment message. When the UE undertakes a concurrent routing area/location area (RA/LA) update procedure corresponding to a circuit-switched (CS) call and a packet-switched (PS) call, a security mode update procedure occurs. For the CS domain, a first security message including ciphering information is transmitted to the UE, and the UE responds. If an ACK message for this response is not received, but the UE receives a second security message including ciphering information for the PS domain, rather than dropping the PS call and transmitting a failure message, the UE treats the second security message as a substitute for the ACK. The UE then processes the second security message normally.

Description

SECURITY MODE UPDATES DURING CELLULAR

RELOCATION TO AVOID CALL DROP

BACKGROUND

Field

[0001] Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to carrier updating procedures during a serving cell change.

Background

[0002] 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 (3GPP). 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 Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks. HSPA is a collection of two mobile telephony protocols, High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA), that extends and improves the performance of existing wideband protocols.

[0003] 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

[0004] Offered is a method of wireless communication. The method includes receiving a first security message for a first domain. The method also includes transmitting a response to the first security message. The method further includes receiving a second security message for a second domain. The second security message is received without receiving an acknowledgment that the response to the first security message was successfully received. The method still further includes treating the second security message as a substitute for the acknowledgment. The method also includes processing the second security message to apply a configuration corresponding to the second security message.

[0005] Offered is an apparatus for wireless communication. The apparatus includes means for receiving a first security message for a first domain. The apparatus also includes means for transmitting a response to the first security message. The apparatus further includes means for receiving a second security message for a second domain. The second security message is received without receiving an acknowledgment that the response to the first security message was successfully received. The apparatus still further includes means for treating the second security message as a substitute for the acknowledgment. The apparatus also includes means for processing the second security message to apply a configuration corresponding to the second security message.

[0006] Also offered is a computer program product for wireless communication in a wireless network. The computer program product includes a non-transitory computer- readable medium having program code recorded thereon. The program code includes program code to receive a first security message for a first domain. The program code also includes program code to transmit a response to the first security message. The program code further includes program code to receive a second security message for a second domain. The second security message is received without receiving an acknowledgment that the response to the first security message was successfully received. The program code still further includes program code to treat the second security message as a substitute for the acknowledgment. The program code also includes program code to process the second security message to apply a configuration corresponding to the second security message.

[0007] Also offered is an apparatus for wireless communication. The apparatus includes a memory and a processor(s) coupled to the memory. The processor(s) is configured to receive a first security message for a first domain. The processor(s) is also configured to transmit a response to the first security message. The processor(s) is further configured to receive a second security message for a second domain. The second security message is received without receiving an acknowledgment that the response to the first security message was successfully received. The processor(s) is still further configured to treat the second security message as a substitute for the acknowledgment. The processor(s) is also configured to process the second security message to apply a configuration corresponding to the second security message.

[0008] This has outlined, rather broadly, the features and technical advantages of the present disclosure in order that the detailed description that follows may be better understood. Additional features and advantages of the disclosure will be described below. It should be appreciated by those skilled in the art that this disclosure may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the teachings of the disclosure as set forth in the appended claims. The novel features, which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages, will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The features, nature, and advantages of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout.

[0010] FIGURE 1 is a block diagram conceptually illustrating an example of a telecommunications system.

[0011] FIGURE 2 is a block diagram conceptually illustrating an example of a frame structure in a telecommunications system. [0012] FIGURE 3 is a block diagram conceptually illustrating an example of a node B in communication with a UE in a telecommunications system.

[0013] FIGURE 4 is a conceptual diagram illustrating an example of a radio protocol architecture for the user and control plane.

[0014] FIGURE 5 illustrates an example of network coverage areas.

[0015] FIGURE6 is a block diagram conceptually illustrating an example of a handover of a UE between cells with different controllers in a telecommunications system.

[0016] FIGURE 7 is a flow chart illustrating a conventional process that may result in an undesired call drop.

[0017] FIGURE 8 is a flow chart illustrating a process operable at a UE for performing a security mode control procedure to avoid the undesired call drop of FIG. 7 in accordance with one example.

[0018] FIGURE9illustrates a method for UE handover between cells with different controllers, where the source controller signals an unrecoverable error.

[0019] FIGURE 10 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

Detailed Description

[0020] 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.

[0021] Turning now to FIGURE 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 FIGURE 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] In a conventional RAN, the service area may be divided into a plurality of routing areas (RAs). Here, each RA is identified by a corresponding routing area identity (RAI). The RA corresponding to a particular RAI is generally defined by the network operator, and includes one or more cells defining a paging area for incoming packet-switched calls. A location area (LA) is a group of one or more RAs, and defines a paging area for incoming circuit- switched calls. The LA is identified by a corresponding location area identity (LAI).

[0028] The RAI is made up of the LAI and a routing area code (RAC). The LAI includes a mobile country code (MCC), a mobile network code (MNC), and a location area code (LAC). With this information, page messages for a particular UE may be routed to the corresponding RNS so that the UE can receive the incoming page.

[0029] FIGURE 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 chip rate in TD-SCDMA is 1.28 Mcps. The frame 202 has two 5 ms subframes 204, and each of the subframes 204 includes seven time slots, TS0 through TS6. The first time slot, TS0, 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. 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. 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 (each with a length of 352 chips) separated by a midamble 214 (with a length of 144 chips) and followed by a guard period (GP) 216 (with a length of 16 chips). The midamble 214 may be used for features, such as channel estimation, while the guard period 216 may be used to avoid inter-burst interference. Also transmitted in the data portion is some Layer 1 control information, including Synchronization Shift (SS) bits 218. Synchronization Shift bits 218 only appear in the second part of the data portion. The Synchronization Shift bits 218 immediately following the midamble can indicate three cases: decrease shift, increase shift, or do nothing in the upload transmit timing. The positions of the SS bits 218 are not generally used during uplink communications.

[0030] FIGURE 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 FIGURE 1, the node B 310 may be the node B 108 in FIGURE 1, and the UE 350 may be the UE 110 in FIGURE 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 (FIGURE 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 (FIGURE 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. [0031] 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 (FIGURE 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.

[0032] 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 (FIGURE 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.

[0033] 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 (FIGURE 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, 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.

[0034] 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. For example, the memory 392 of the UE 350 may store a security message module 391 which, when executed by the controller/processor 390, configures the UE 350 to treat a second security message as a substitute for an acknowledgement of a first security message. 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.

[0035] In a wireless telecommunication system, the communication protocol architecture may take on various forms depending on the particular application. For example, in a 3GPP UMTS system, the signaling protocol stack is divided into a Non- Access Stratum (NAS) and an Access Stratum (AS). The NAS provides the upper layers, for signaling between the UE 110 and the core network 104 (referring to FIGURE 1), and may include circuit switched and packet switched protocols. The AS provides the lower layers, for signaling between the UTRAN and the UE, and may include a user plane and a control plane. Here, the user plane or data plane carries user traffic, while the control plane carries control information (i.e., signaling).

[0036] Turning to FIGURE 4, the AS is shown with three layers: Layer 1, Layer 2, and Layer 3. Layer 1 is the lowest layer and implements various physical layer signal processing functions. Layer 1 will be referred to herein as the physical layer 406. The data link layer, called Layer 2 408, is above the physical layer 406 and is responsible for the link between the UE and Node B over the physical layer 406.

[0037] At Layer 3, the RRC layer 416 handles the control plane signaling between the UE and the Node B. RRC layer 416 includes a number of functional entities for routing higher layer messages, handling broadcasting and paging functions, establishing and configuring radio bearers, etc.

[0038] In the illustrated air interface, the L2 layer 408 is split into sublayers. In the control plane, the L2 layer 408 includes two sublayers: a medium access control (MAC) sublayer 410 and a radio link control (RLC) sublayer 412. In the user plane, the L2 layer 408 additionally includes a packet data convergence protocol (PDCP) sublayer 414. Although not shown, the UE may have several upper layers above the L2 layer 408 including a network layer (e.g., IP layer) that is terminated at a PDN gateway on the network side and an application layer that is terminated at the other end of the connection (e.g., far end UE, server, etc.).

[0039] The PDCP sublayer 414 provides multiplexing between different radio bearers and logical channels. The PDCP sublayer 414 also provides header compression for upper layer data packets to reduce radio transmission overhead, security by ciphering the data packets, and handover support for UEs between Node Bs.

[0040] The RLC sublayer 412 generally supports an acknowledged mode (AM) (where an acknowledgment and retransmission process may be used for error correction), an unacknowledged mode (UM), and a transparent mode for data transfers, and provides segmentation and reassembly of upper layer data packets and reordering of data packets to compensate for out-of-order reception due to a hybrid automatic repeat request (HARQ) at the MAC layer. In the acknowledged mode, RLC peer entities such as an RNC and a UE may exchange various RLC protocol data units (PDUs) including RLC Data PDUs, RLC Status PDUs, and RLC Reset PDUs, among others. In the present disclosure, the term "packet" may refer to any RLC PDU exchanged between RLC peer entities.

[0041] The MAC sublayer 410 provides multiplexing between logical and transport channels. The MAC sublayer 410 is also responsible for allocating the various radio resources (e.g., resource blocks) in one cell among the UEs. The MAC sublayer 410 is also responsible for HARQ operations.

[0042] Some base stations in a network may cover only a portion of a geographical area. FIGURE 5 illustrates coverage of a network, such as a TD-SCDMA network, as represented by individual base stations. A geographical area 500 may include multiple TD-SCDMA base stations, illustrated by towers 502a, 502b, and 502c, each serving their own respective geographic locations, illustrated by geographic cells 504a, 504b, and 504c, respectively. A user equipment (UE) 506 may move from one cell, such as cell 504a, to another cell, such as a cell 504b. The movement of the UE 506 may specify a handover or a cell reselection. The different base stations may be coordinated through a single radio network controller (RNC) or through different RNCs. If the base stations are controlled by different RNCs, they may be considered to be on different subsystems.

[0043] FIGURE 6 illustrates a telecommunications system where the radio access network 602 contains more than one Radio Network Controller (RNC). The RNCs may be connected to different portions of the core network 604 (as shown), or may connect to the same core network components. As illustrated, a UE 110 communicates with a source NodeB 108a of a first Radio Network Subsystem 107a controlled by a first RNC 106a. A handover of the UE 110 to a target NodeB 108b of a second Radio Network Subsystem 107b is initiated (SRNS relocation), and shown by handover direction 610. The second RNC 106b of the second Radio Network Subsystem is independent of the first "source" RNC 106a.

SECURITY MODE UPDATES DURING RELOCATION TO AVOID CALL DROP

[0044] In particular, an SRNS relocation moves the connection between the RNC 106 and the core network 104 from the source RNC 106a to the target RNC 106b. In some examples (i.e., inter-SGSN SRNS relocation), the SGSN 118 may be changed in accordance with the SRNS relocation, while in other examples (i.e., intra-SGSN SRNS relocation), the same SGSN 118 may be utilized by the source SRNS and the target SRNS. When an SRNS relocation occurs, it ideally occurs without changing the radio resources, and without interrupting the user data flow.

[0045] When a UE completes SRNS relocation, the UE can detect if a location area identity (LAI) and/or a routing area identity (RAI) has changed based on the handover command. If one or both of the LAI and/or RAI has changed, the UE may initiate a corresponding cell update procedure. In particular, when both the LAI and RAI have changed, update procedures for the RA and LA may commence concurrently.

[0046] In accordance with an aspect of the disclosure, it has been discovered that the above-described combined RA/LA update procedure, which may occur in response to the SRNS relocation, can potentially result in a call drop, particularly in a TD- SCDMA network as the PS and CS domains on the network side may not be properly synchronized/sequenced.

[0047] FIGURE 7 is a flow chart illustrating a process 700 showing one example of this problem case, which can result in an undesired call drop. Here, the process 700 corresponds to a conventional UE 110 in communication with a UTRAN 102, which may utilize a TD-SCDMA air interface.

[0048] In the illustrated example, at block 702, the UE operates in connected mode, having an ongoing circuit switched (CS) call or an ongoing packet switched (PS) call. At block 704, as the UE moves to a location served by a cell in a different RNS than the one from which the calls originated, an SRNS relocation may take place. Here, to move the CS and PS calls to the target RNS, at block 706 a concurrent RA/LA update procedure may take place.

[0049] That is, when both the CS and PS calls are connected, and the SRNS relocation occurs, the UE may trigger update procedures for the LAI and the RAI. Here, prior to the UTRAN 102 accepting the UE at the new target RNS and fully performing the simultaneous RA/LA update procedure, in accordance with a security mode control procedure, as defined in 3GPP TS 25.331 (RRC Protocol Specification), the UTRAN 102 generally transmits security mode commands to the UE to authenticate the UE. Here, the security mode commands include a CS security mode command, for the circuit switched domain service, and a PS security mode command, for the packet switched domain service. [0050] Here, an RRC security mode control procedure is utilized in UMTS networks to trigger the start or stop of ciphering and integrity protection between the UE and the UTRAN, as well as for triggering the change of the ciphering and integrity keys during the connection. In a typical network configuration, two ciphering keys are utilized by the UE, for each of the PS domain services and the CS domain services, respectively.

[0051] That is, at block 708, the UTRAN 102 may send a first security message (e.g., the CS Security Mode Command) to the UE. When the UE receives the CS Security Mode Command message, it processes the message and applies the new configuration. Thereafter, at block 710 the UE may transmit to the UTRAN 102 a CS Security Mode Complete message to indicate the successful handling of the CS security mode command message.

[0052] At layer 2, 408 (referring to FIGURE 4), after transmitting the CS Security Mode Complete message, the UE may expect the UTRAN 102 to transmit an acknowledgment (ACK) indicating successful receipt of this message. However, for various reasons including but not limited to interference, fading, etc., the UE may fail to receive this L2 ACK message in the first several transmission attempts by the NodeB. In this case, because the ACK was not received in time, the UE may continue to poll the network for resending of the L2 ACK.

[0053] At this time, at block 714 it may be the case that the UE receives a second security message, that is, a PS Security Mode Command message. As with the above CS Security Mode Command, the PS Security Mode Command message is intended to provide security information such as a ciphering key for the PS domain.

[0054] However, according to current specifications, because the L2 ACK message was not received at the UE corresponding to its transmission of the CS Security Mode Complete message at block 710, when the UE receives the PS Security Mode Command at block 714, at block 716 the UE transmits a Security Mode Command Failure message to the UTRAN 102. In response, at block 718 the UTRAN 102 transmits an RRC Connection Release message to the UE, causing the PS call to drop. If the UE received the L2 ACK at block 712, at block 720 conventional security mode messaging occurs.

[0055] Thus, one or more aspects of the disclosure alter the security mode operation described above in relation to FIGURE 7, in order to avoid this undesired call drop that may occur when the L2 ACK message corresponding to the CS Security Mode Complete message is not received at the UE. That is, in accordance with an aspect of the present disclosure, the UE may be configured such that even though it receives the second security message without having received the ACK message corresponding to the first security message, as long as the second security message passes the integrity protection (IP) check, the UE considers the first security procedure to be complete. That is, contrary to the conventional protocol, the UE according to an aspect of the disclosure does not send the security failure message to the UTRAN, and continues the PS call.

[0056] FIGURE 8 is a flow chart illustrating one example of a process 800 operable at the UE for undertaking security mode command messaging in accordance with an aspect of the disclosure. Here, blocks 802 to 812 and 820 are substantially the same as steps 702 to 712 and 720 described above in relation to FIGURE 7. That is, during an SRNS relocation procedure (block 804), while undergoing a combined RA/LA update procedure (block 806), the UE receives a first security message (e.g., the CS Security Mode Command) at block 808 and sends a corresponding CS Security Mode Complete message at block 810. Here, as above, at block 812 the UE may fail to receive the expected L2 ACK message corresponding to its transmission of the CS Security Mode Complete message at block 810. Further, as above, at block 814 the UE may receive a second security message (e.g., the PS Security Mode Command). Moreover, If the UE received the L2 ACK at block 812, at block 820 conventional security mode messaging occurs.

[0057] In accordance with an aspect of the disclosure, at 816 the UE may determine whether the second security message (here, the PS Security Mode Command) passes a suitable integrity protection (IP) check, and if so, the UE may treat the second security message as a substitute for the L2 ACK it expected corresponding to the CS Security Mode Complete message. That is, rather than becoming confused by the receipt of the second security message prior to the receipt of the conventional L2 ACK message and transmitting a Security Mode Command Failure message, as would occur in a conventional UE, here, the UE may process the second security message (e.g., the PS Security Mode Command) as normal, treating the PS Security Mode Command message received at block 814 as a substitute for the ACK. Thus, at block 818 the UE may process the received PS Security Mode Command, e.g., applying the new configuration and continuing with the RA/LA update procedure as if the ACK for the CS Security Mode Complete message had been properly received. [0058] In various aspects of the disclosure, the UE may further be configured to process the L2 ACK in the same way as in a conventional UE if it is received, but to treat the PS Security Mode Command as a substitute for this ACK only if the ACK is not received.

[0059] In another aspect of the disclosure, the order of the PS Security Mode Command and the CS Security Mode Command may be rearranged, without substantially affecting the operation of the process 800 described above.

[0060] Although the example of FIGURE 8 illustrates aspects of the disclosure in reference to an SRNS relocation procedure, the teachings herein may be applied to a number of different scenarios where a second security message may be treated as a substitute for an acknowledgment of a response to a first security message. While this may take place in the context of engaging in a relocation procedure, other contexts are also possible. Thus, blocks 802-806 may not necessarily apply in each situation. Other blocks may also be optional.

[0061] FIGURE 9shows an example of a wireless communication method 900 that may be used by the controller/processor 390 of the UE 110/350 to avoid a failure of security authorization. A UE receives a first security message for a first domain, as shown in block 902. The UE also transmits a response to the first security message, as shown in block 904. The UE receives a second security message for a second domain, as shown in block 906. The second security message is received without receiving an acknowledgment that the response to the first security message was successfully received. The UE treats the second security message as a substitute for the acknowledgement (ACK), as shown in block 908. The UE then processes the second security message to apply a configuration corresponding to the second security message, as shown in block 910.

[0062] FIGURE 10 is a diagram illustrating an example of a hardware implementation for an apparatus 1000 employing a processing system 1014. The processing system 1014 may be implemented with a bus architecture, represented generally by the bus 1024. The bus 1024 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 1014 and the overall design constraints. The bus 1024 links together various circuits including one or more processors and/or hardware modules, represented by the processor 1022 the modules 1002, 1004, and 1006 and the non-transitory computer- readable medium 1026. The bus 1024 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

[0063] The apparatus includes a processing system 1014 coupled to a transceiver 1030. The transceiver 1030 is coupled to one or more antennas 1020. The transceiver 1030 enables communicating with various other apparatus over a transmission medium. The processing system 1014 includes a processor 1022 coupled to a non-transitory computer-readable medium 1026. The processor 1022 is responsible for general processing, including the execution of software stored on the computer-readable medium 1026. The software, when executed by the processor 1022, causes the processing system 1014 to perform the various functions described for any particular apparatus. The computer-readable medium 1026 may also be used for storing data that is manipulated by the processor 1022 when executing software.

[0064] The processing system 1014 includes a receiving module 1002 for receiving security messages. The processing system 1014 includes a transmitting module 1004 for transmitting a response to security messages. The processing system 1014 includes a processing module 1006 for treating a second security message as an acknowledgment that a response to the first security message was successfully received as well as for processing the second security message. The modules may be software modules running in the processor 1022, resident/stored in the computer readable medium 1026, one or more hardware modules coupled to the processor 1022, or some combination thereof. The processing system 614 may be a component of the UE 110 and may include the memory 392, and/or the controller/processor 390.

[0065] In one configuration, an apparatus such as a UE 110/350 is configured for wireless communication including means for receiving messages. In one aspect, the receiving means may be the antennas 352/1020, the receiver 354, the transceiver 1030, the receive processor 370, the controller/processor 390/1022, the memory 392, computer-readable medium 1026, security message module 391, receiving module 1002, and/or the processing system 1014 configured to perform the receiving means.

[0066] The UE is also configured to include means for transmitting messages. In one aspect, the transmitting means may be the antennas 352/1020, the transmitter 356, the transceiver 1030, the transmit processor 380, the controller/processor 390/1022, the memory 392, computer-readable medium 1026, security message module 391, transmitting module 1004, and/or the processing system 1014 configured to perform the transmitting means. In one aspect the means 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.

[0067] The UE is also configured to include means for processing, including means for treating a second security message as an acknowledgment of a response to a first security message. In one aspect, the processing means may be the controller/processor 390/1022, the memory 392, computer-readable medium 1026, security message module 391, processing module 1006, and/or the processing system 1014 configured to perform the processing means. In one aspect the means 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.

[0068] Several aspects of a telecommunications system has been presented with reference to 3GPP in general, and to TD-SCDMA in particular. 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.

[0069] 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.

[0070] 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 non-transitory 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).

[0071] 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.

[0072] 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.

[0073] 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."

Claims

CLAIMS WHAT IS CLAIMED IS:

1. A method of wireless communication operable at a user equipment (UE), comprising:

receiving a first security message for a first domain;

transmitting a response to the first security message;

receiving a second security message for a second domain, without receiving an acknowledgment that the response to the first security message was successfully received;

treating the second security message as a substitute for the acknowledgment; and processing the second security message to apply a configuration corresponding to the second security message.

2. The method of claim 1, in which treating the second security message as a substitute for the acknowledgment further comprises determining that the second security message passes an integrity protection (IP) check.

3. The method of claim 1, further comprising engaging in a relocation procedure.

4. The method of claim 3, in which the relocation procedure is a serving radio network subsystem (SRNS) relocation procedure.

5. The method of claim 1, in which the first domain comprises a circuit- switched (CS) domain, and the second domain comprises a packet-switched (PS) domain.

6. The method of claim 5, in which the first security message comprises a CS Security Mode Command message and the second security message comprises a PS Security Mode Command message.

7. The method of claim 1, in which the response to the first security message comprises a Security Mode Complete message.

8. An apparatus for wireless communication, comprising:

means for receiving a first security message for a first domain;

means for transmitting a response to the first security message;

means for receiving a second security message for a second domain, without receiving an acknowledgment that the response to the first security message was successfully received;

means for treating the second security message as a substitute for the acknowledgment; and

means for processing the second security message to apply a configuration corresponding to the second security message.

9. The apparatus of claim 8, in which the first domain comprises a circuit- switched (CS) domain, and the second domain comprises a packet-switched (PS) domain.

10. The apparatus of claim 9, in which the first security message comprises a CS Security Mode Command message and the second security message comprises a PS Security Mode Command message.

11. A computer program product for wireless communication in a wireless network, comprising:

a non-transitory computer-readable medium having program code recorded thereon, the program code comprising:

program code to receive a first security message for a first domain;

program code to transmit a response to the first security message;

program code to receive a second security message for a second domain, without receiving an acknowledgment that the response to the first security message was successfully received;

program code to treat the second security message as a substitute for the acknowledgment; and program code to process the second security message to apply a configuration corresponding to the second security message.

12. The computer program product of claim 11 in which the first domain comprises a circuit- switched (CS) domain, and the second domain comprises a packet- switched (PS) domain.

13. The computer program product of claim 12, in which the first security message comprises a CS Security Mode Command message and the second security message comprises a PS Security Mode Command message.

14. An apparatus for wireless communication, comprising:

a memory; and

at least one processor coupled to the memory and configured:

to receive a first security message for a first domain;

to transmit a response to the first security message;

to receive a second security message for a second domain, without receiving an acknowledgment that the response to the first security message was successfully received;

to treat the second security message as a substitute for the acknowledgment; and

to process the second security message to apply a configuration corresponding to the second security message.

15. The apparatus of claim 14, in which the at least one processor configured to treat the second security message as a substitute for the acknowledgment further comprises the at least one processor configured to determine that the second security message passes an integrity protection (IP) check.

16. The apparatus of claim 14, in which the at least one processor is further configured to engage in a relocation procedure.

17. The apparatus of claim 16, in which the relocation procedure is a serving radio network subsystem (SRNS) relocation procedure.

18. The apparatus of claim 14, in which the first domain comprises a circuit- switched (CS) domain, and the second domain comprises a packet-switched (PS) domain.

19. The apparatus of claim 18, in which the first security message comprises a CS Security Mode Command message and the second security message comprises a PS Security Mode Command message.

20. The apparatus of claim 14, in which the response to the first security message comprises a Security Mode Complete message.