HK1161484A - Method and apparatus for resolving paging monitoring conflicts in multimode wireless equipment - Google Patents

Description

Method and apparatus for resolving paging monitoring conflicts in a multimode wireless device

Cross Reference to Related Applications

This application claims the benefit of U.S. provisional patent application No.61/261,059 entitled "SYSTEM and method FOR producing polymeric materials and method FOR producing same", filed on 13.11.2009, the entire contents of which are expressly incorporated herein by reference.

Technical Field

Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to paging systems in multi-mode wireless communication systems.

Background

Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcast, and so on. The network is typically a multiple access network that supports multiple users communicating by sharing the available network resources. An example of such a network is the Universal Terrestrial Radio Access Network (UTRAN). UTRAN is a Radio Access Network (RAN) defined as part of the universal mobile telecommunications system (UTMS), which is a third generation (3G) mobile telephony technology supported by the third generation partnership project (3 GPP). UMTS is a successor to global system for mobile communications (GSM) technology, currently supporting 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, various providers in china are pushing WCDMA and/or TD-SCDMA as the underlying air interface in the UTRAN architecture, with the existing GSM infrastructure as the core network. 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.

As the demand for mobile broadband access continues to increase, research and development continue to advance the development of UMTS technology, not only to meet the increasing demand for mobile broadband access, but also to advance and enhance the user experience with mobile communications.

Disclosure of Invention

Various aspects of the present disclosure enable a multi-mode UE to operate in idle mode while registered with multiple Radio Access Technologies (RATs), such as TD-SCDMA and WCDMA networks, and to monitor paging messages, with a reduced likelihood of paging collisions and missed calls. If paging collisions are encountered at a particular cell, cell reselection to another cell may be utilized to change cells and avoid collisions. The probability of paging collisions is small due to the short duration of the paging indicator message (e.g., for TD-SCDMA PICH, (10+ M)/1280 ≈ 2% (where M ═ 10ms, DRX _ cycle ≈ 1280ms)), the UE may have infrequent paging indicator monitoring collisions, and when collisions actually occur, it is likely that the UE will find a neighboring cell without collisions. Further, since the SFN of WCDMA/TD-SCDMA network is asynchronous, it is likely that a new cell without PICH monitoring collision will be found.

In one aspect of the present disclosure, a wireless communication method includes: determining the existence of a paging collision between a first cell of a first network and a second cell of a second network; determining at least one candidate cell in one of the first network or the second network to avoid the paging collision; and performing cell reselection from one of the first cell or the second cell to the candidate cell.

In another aspect of the present disclosure, an apparatus for wireless communication includes: means for determining the existence of a paging collision between a first cell of a first network and a second cell of a second network; means for determining at least one candidate cell in one of the first network or the second network to avoid the paging collision; and means for performing cell reselection from one of the first cell or the second cell to the candidate cell.

In yet another aspect of the disclosure, a computer program product includes a computer-readable medium having code for: determining the existence of a paging collision between a first cell of a first network and a second cell of a second network; determining at least one candidate cell in one of the first network or the second network to avoid the paging collision; and performing cell reselection from one of the first cell or the second cell to the candidate cell.

In still another aspect of the present disclosure, an apparatus for wireless communication includes: at least one processor; and a memory coupled to the at least one processor, wherein the at least one processor is configured to: determining the existence of a paging collision between a first cell of a first network and a second cell of a second network; determining at least one candidate cell in one of the first network or the second network to avoid the paging collision; and performing cell reselection from one of the first cell or the second cell to the candidate cell.

Drawings

Fig. 1 illustrates a multiple access wireless communication system according to one aspect of the present disclosure;

FIG. 2A is a schematic diagram of a TD-SCDMA frame structure;

FIG. 2B is a schematic diagram of a W-CDMA frame structure;

fig. 3 is a block diagram of a node B communicating with a UE in accordance with one aspect of the present disclosure;

FIG. 4 is a schematic diagram of a WCDMA cell overlapping a TD-SCDMA cell;

FIG. 5 is a timing diagram illustrating a paging interval in a WCDMA network;

FIG. 6 is a timing diagram illustrating a paging interval in a TD-SCDMA network;

FIG. 7 is a timing diagram illustrating overlapping frames in a WCDMA network and a TD-SCDMA network; and

fig. 8 is a flow chart illustrating a process according to an aspect of the present disclosure.

Detailed Description

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. It will be apparent, however, to one skilled in the art that these specific details may not be required in order to practice the concepts. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Referring now to fig. 1, a block diagram illustrating an example of a telecommunications system 100 is shown. The various concepts presented throughout this disclosure may be implemented by a variety of different telecommunications systems, network architectures, and communication standards. By way of example and not limitation, the scheme of the present disclosure shown in fig. 1 is given with reference to a UMTS system utilizing the TD-SCDMA standard. However, those skilled in the art will appreciate that the same or similar functions and modules may be utilized in a UMTS system utilizing the WCDMA 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, broadcast, and/or other services. The RAN 102 may be divided into a plurality of Radio Network Subsystems (RNSs), such as an RNS107, each of which is controlled by a Radio Network Controller (RNC), such as an RNC 106. For clarity, only the RNC 106 and RNS107 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 a device mainly responsible for allocation, reconfiguration, and release of radio resources within the RNS 107. The RNC 106 may be interconnected to other RNCs (not shown) in the RAN 102 by various types of interfaces (e.g., direct physical connections, virtual networks, etc.) using any suitable transport network.

The geographical area covered by the RNS107 may be divided into a number of cells with each cell being served by a radio transceiver device. The 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 RNSs 107 may include any number of wireless node bs. The node bs 108 provide wireless access points to the core network 104 for any number of mobile devices. 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. A mobile device 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 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 purposes of illustration, 3 UEs 110 are shown in communication with node B108. The Downlink (DL), also called the forward link, refers to the communication link from the node B to the UE, and the Uplink (UL), also called the reverse link, refers to the communication link from the UE to the node B.

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

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 (e.g., RNC 106) may be connected to MSC 112. The MSC112 is a device that controls call setup, call routing, and UE mobility functions. The MSC112 also includes a Visitor Location Register (VLR) (not shown) that contains subscriber-related information for the UE during its coverage area of the MSC 112. The GMSC 114 provides a gateway for the UE through the MSC112 to access the circuit-switched network 116. The GMSC 114 includes a Home Location Register (HLR) (not shown) that contains subscriber data, such as data reflecting the details of the services to which a particular subscriber 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.

The core network 104 also employs a Serving GPRS Support Node (SGSN)118 and a Gateway GPRS Support Node (GGSN)120 to support packet-data services. GPRS refers to general packet radio service designed to provide packet-data services at speeds higher than those available for standard GSM circuit-switched data services. GGSN 120 provides a connection for RAN 102 to 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 GGSN 120 is to provide UE110 with packet-based network connectivity. Data packets are transmitted between the GGSN 120 and the UE110 through the SGSN 118, where the SGSN 118 performs mainly the same functions in the packet-based domain as the MSC112 performs in the circuit-switched domain.

The UMTS air interface is a spread spectrum direct sequence code division multiple access (DS-CDMA) system. Spread spectrum DS-CDMA spreads user data over a much wider bandwidth by multiplying by a pseudo-random bit sequence called chips. The TD-SCDMA standard is based on this direct sequence spread spectrum technique and also requires Time Division Duplexing (TDD) instead of 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 node B108 and UE110, but divides the uplink and downlink transmissions into different time slots in the carrier.

Fig. 2A shows a frame structure 200 of a TD-SCDMA carrier. As shown, the TD-SCDMA carrier has a frame 202 of length 10 ms. The frame 202 has 2 subframes 204 of 5ms, each subframe 204 including 7 slots TS0-TS 6. A first time slot TS0 is typically allocated for downlink communications and a second time slot TS1 is typically allocated for uplink communications. The remaining time slots TS 2-TS 6 may be used for uplink or downlink, which allows for greater flexibility in the uplink or downlink direction during higher data transmission times. A downlink pilot time slot (DwPTS)206, a Guard Period (GP)208, and an uplink pilot time slot (UpPTS)210 (also referred to as an uplink pilot channel (UpPCH)) are located between TS0 and TS 1. Each time slot TS0-TS6 may allow data transmission to be multiplexed over a maximum of 16 code channels. The data transmission on the code channel comprises 2 data portions 212 separated by a midamble (midamble)214 followed by a Guard Period (GP) 216. The midamble 214 may be used for functions such as channel estimation, while the GP 216 may be used to avoid interference between bursts (bursts).

Fig. 2B shows a frame structure of a WCDMA carrier. As shown, the WCDMA carrier has a frame 250, which is 10ms in length. The content of the frames 250, and of each frame, depends on the channel in question, which may be a Paging Channel (PCH), a Broadcast Channel (BCH), a Random Access Channel (RACH), etc.

Fig. 3 is a block diagram of a node B310 in a RAN300 in communication with a UE350, where the RAN300 may be the RAN 102 of fig. 1, the node B310 may be the node B108 of fig. 1, and the UE350 may be the UE110 of fig. 1. In downlink communications, a transmit processor 320 may receive data from a data source 312 and control signals from a controller/processor 340. Transmit processor 320 provides various signal processing functions for the data, control signals, and reference signals (e.g., pilot signals). For example, transmit processor 320 may provide a Cyclic Redundancy Check (CRC) code for error detection, encode and interleave for Forward Error Correction (FEC), map 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), etc.), spread with an Orthogonal Variable Spreading Factor (OVSF), and multiply by a scrambling code to produce a series of symbols. The channel estimates from channel processor 344 may be used by controller/processor 340 to determine the coding, modulation, spreading, and/or scrambling schemes for transmit processor 320. These channel estimates may be derived from reference signals transmitted by the UE350 or from feedback contained in the midamble 214 (fig. 2A) 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 midamble 214 (fig. 2A) from the controller/processor 340 with the symbols, resulting in a series of frames. The frames are then provided to a transmitter 332, which provides various signal conditioning functions including amplification, filtering, and modulation of the frames onto a carrier for downlink transmission over a wireless medium through a smart antenna 334. The smart antenna 334 may be implemented by a beam steering bi-directional adaptive antenna array or other similar beam technology.

At the UE350, 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. 2A) 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 B310. More specifically, the receive processor 370 descrambles and despreads the symbols, and then determines the most likely signal constellation points transmitted by the node B310 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 code is then checked to determine whether the decoding of the frame was successful. The data carried by the successfully decoded frames is then provided to a data sink 372, which represents applications running in the UE350 and/or various user interfaces (e.g., a display). Control signals carried by the successfully decoded frames are provided to a controller/processor 390. When frames are not successfully decoded by receive processor 370, controller/processor 390 may also support retransmission requests for those frames using an Acknowledgement (ACK) and/or Negative Acknowledgement (NACK) protocol.

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 UE350 and various user interfaces (e.g., a keyboard). Similar to the functionality described in connection with the downlink transmission by the node B310, 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. A channel estimate derived by a channel processor 394 from a reference signal transmitted by the node B310 or from feedback contained in a midamble transmitted by the node B310 may be used to select an appropriate coding, modulation, spreading, and/or scrambling scheme. The symbols generated by the transmit processor 380 are provided to a transmit frame processor 382 to create a frame structure. The transmit frame processor 382 creates this frame structure by multiplexing the midamble 214 (fig. 2A) from the controller/processor 390 with the symbols, 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 modulation of the frames onto a carrier for uplink transmission over the wireless medium via the antenna 352.

The uplink transmissions are processed at the node B310 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. 2A) to a 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 a controller/processor, respectively. Controller/processor 340 may also support retransmission requests for some frames using an Acknowledgement (ACK) and/or Negative Acknowledgement (NACK) protocol if those frames fail to be successfully decoded by the receiving processor.

Controllers/processors 340 and 390 may be used to direct operations at node B310 and UE350, respectively. For example, 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 B310 and the UE350, respectively. A scheduler/processor 346 at the node B310 may be used to allocate resources to the UEs and schedule downlink and/or uplink transmissions for the UEs.

The following details relate to the scenario illustrated in fig. 4, which is a conceptual diagram illustrating a network topology in which a UE 410 is within the geographic coverage area of two different wireless networks, namely a first network 420 utilizing a TD-SCDMA air interface, and a second network 430 utilizing a WCDMA air interface, overlapping the first network 420. The UE 410 may be a multi-mode terminal capable of wireless communication using more than one air interface. Here, the UE can utilize the first network 420 over a TD-SCDMA air interface and the second network 430 over a WCDMA air interface, for example.

As will be discussed in further detail, the examples including TD-SCDMA and WCDMA are merely illustrative in nature, and in various aspects of the disclosure, a multimode UE may be within the geographic coverage area of two or more of any number of wireless networks, including but not limited to TD-SCDMA, WCDMA, CDMA2000, 3GPP LTE, and LTE advanced networks.

Returning to the scenario illustrated in fig. 4, the respective core networks of these Radio Access Technologies (RATs) may not communicate with each other, and the multimode UE 410 may subscribe to both networks independently. That is, the UE 410 may have 2 independent Subscriber Identity Modules (SIMs): there is one SIM for each of the networks 420, 430 and can register with both networks to receive separate paging messages in order to receive mobile terminated calls in idle mode. When subscribed, the multimode UE 410 may enter an idle mode in both networks and may further monitor paging messages of both networks in the idle mode, as discussed in further detail below.

The multimode UE 410 may have a mixed configuration in order to monitor separate paging messages. That is, the UE may periodically switch between the WDMA network 430 and the TD-SCDMA network 420 to check for paging messages. This may occur when the multi-mode UE 410 is capable of transmitting to or receiving from one RAT at a time. For example, the multimode UE 410 may include a single RF chain, or the multimode UE 410 may have limited processing power.

Fig. 5 is a timing diagram conceptually illustrating a paging cycle in a WCDMA RAT. In WCDMA, a Paging Indicator Channel (PICH)510 is utilized on the downlink to indicate that the UE can find a paging message in the Paging Channel (PCH). The PCH is provided on a secondary common control physical channel (S-CCPCH) 520. That is, a UE in idle mode typically listens to the PICH at certain repetitive paging indicator intervals 530, e.g., monitors the PICH510 for up to 10 ms. There may be a 2ms delay 540 between the end of the paging indicator interval 530 on the PICH510 and the beginning of the paging interval 550 on the S-CCPCH 520 to provide the UE with time to switch to the S-CCPCH 520. That is, when the UE finds the appropriate paging indicator on the PICH510, it may monitor the S-CCPCH 520 for a paging interval 550 of 10ms after a delay 540 of 2ms, where a paging type 1 message is sent to determine whether the network is initiating communication with the UE.

In WCDMA, different paging cycles may be configured with different paging offsets determined at least in part by the International Mobile Subscriber Identity (IMSI) stored in the SIM in the UE, or by the telephone number, etc. That is, while the paging cycle may be fixed in some instances, the offset from the beginning of the cycle may vary from device to device depending on the IMSI or phone number. As a simplified example, if the paging cycle corresponds to 128 WCDMA frames and the paging offset is 3 frames, the paging interval will occur in frame numbers 131, 259, 387, etc.

Thus, equation (1) below may be used to determine a System Frame Number (SFN) corresponding to a paging occasion in which a WCDMA node b (nb) sends a paging message to a UE:

paging_occasion_wcdma＝(IMSI div K)mod DRX_cycle_wcdma+i*

DRX_cycle_wcdma(1)

the Discontinuous Reception (DRX) cycle length may determine a paging cycle length. For example, for Circuit Switched (CS) services, the DRX cycle length may be a number of 10ms radio frames, the number of frames being determined by the core network, with possible values including: 2⁶(i.e., 640ms), 2⁷、2⁸And 2⁹(i.e., 5.12 seconds). For Packet Switched (PS) services, the DRX cycle length may be negotiated between the UE and the core network using an Attach (Attach) procedure known to those skilled in the art, with possible values including: 2³(i.e., 80ms), 2⁴、2⁵、2⁶、2⁷、2⁸And 2⁹(5.12 seconds).

The parameter K corresponds to the number of S-CCPCHs supported by the NB (up to 16). The operator "div" represents division. The parameter i corresponds to an integer.

Different wcdma nbs may utilize different respective SFNs (e.g., corresponding to 12-bit radio frame numbers, from 0 to 4095), and thus the paging intervals for different UMTS base stations may differ in absolute time. Further, frame boundaries (i.e., absolute times of start and end of frames from respective NBs) are generally not synchronized from one wcdma NB to another.

Fig. 6 is a timing diagram conceptually illustrating a paging cycle in a TD-SCDMA RAT. In TD-SCDMA, a UE configured for idle mode Discontinuous Reception (DRX) operation may monitor certain repetitive paging blocks of the Paging Indicator Channel (PICH) 602. The DRX cycle may be determined by a circuit switched Core Network (CN) provided by higher layer communications, for example, in a system information message, or may be negotiated between the packet switched CN and the UE. The final DRX cycle length may be the shortest of the circuit switched CN and the packet switched CN.

The UE may then listen to the PICH602, starting with the associated paging _ occase _ td, which is given by equation (2). That is, equation (2) below may be used to determine the SFN corresponding to the paging occasion in which the TD-scdma nb transmits a paging message to the UE:

paging_occasion_td＝(IMSI div K)mod(DRX_cycle_td div PBP)*PBP

+frame_offset+j*DRX_cycle_td+p (2)

the Paging Block Period (PBP)604 corresponds to the number of frames between 2 consecutive paging blocks, and the frame _ offset corresponds to the frame offset 606 of the first frame in the PBP 604, which is given in the system information message. K corresponds to the number of secondary common control physical channels (S-CCPCH) that can carry the Paging Channel (PCH). The parameter j corresponds to an integer. The parameter p is defined in the following formula (3).

During each PBP 604, there may be N_PICHA PICH602 of a frame, and may have a PICH with N_PCH2 frames of PCH 608. Further, there may be N from the end of PICH to the beginning of PCH 608_GAPAnd (4) one frame. The UE may assign to N in PICH block 602_PICHOne of the frames and the assignment to N in PCH 608_PCHOne of the paging groups (e.g., each paging group PG has 2 frames) that corresponds to an associated paging occasion. When the paging message corresponding to the particular UE is determined to be within the PCH paging group, it indicates that the network is initiating communication with the UE.

Parameter N_PICH、N_GAPAnd N_PCHMay be determined based on system information.

The UE may listen to only one specific frame p of PICH602 according to equation (3):

p＝[(IMSI div 8192)mod(N_PICH*NPI)]div NPI (3)

the NPI is the number of paging indicators per frame in the PICH602, which may be derived from system information.

Thus, the UE may select only one frame of the paging block per DRX cycle to monitor the PICH 602. That is, the UE can only monitor PICH frames located at the following:

paging_occasion_td+p (4)

from a timing perspective, TD-SCDMA frame boundaries may be synchronized or aligned for different NBs, unlike WCDMA frames, but the System Frame Number (SFN) may generally be unsynchronized or unaligned for different NBs.

However, since the multimode terminal may monitor paging indication messages (e.g., the PICH602 or the paging indicator 530) in the WCDMA and TD-SCDMA networks, it may occur when paging monitoring for the WCDMA network and paging monitoring for the TD-SCDMA network collide. That is, because a multi-mode UE can only receive from one network at a time, the UE can only select one network to monitor, and thus it may miss some paging messages from other networks. Further, since the paging intervals in both networks are repetitive and may be periodic, it is possible that if one paging indication collision occurs, the paging collision will occur repeatedly again, causing serious problems of missed calls, SMS messages, and the like.

Therefore, in an aspect of the present disclosure, paging collision may be avoided by: detecting a paging collision condition, finding and selecting a neighboring cell where no paging collision will occur and performing cell reselection to the selected cell, thereby monitoring a paging indicator channel (and thereafter a paging channel, which is dependent on the RAT) from the reselected cell. That is, the UE may utilize WCDMA and TD-SCDMA networks according to each of the general procedures until a paging collision occurs or is expected to occur. When paging collisions are detected, cell reselection by one or both base stations may be performed using the processing described below in an attempt to avoid collisions. Here, cell reselection may include idle handover to a neighboring cell, or any suitable process of acquiring a neighboring cell to avoid paging collision.

Paging collisions may exist when collisions actually occur, i.e., when it is detected that the UE receives paging indicator messages through both networks simultaneously. In one aspect of the disclosure, a UE may preemptively (preemptively) check for future collisions based on measurements of timing of paging indicator messages on respective RATs. That is, before actual collision occurs (i.e., during the time when paging indicator messages are not received from both networks simultaneously but such a condition is expected to occur), the UE may utilize the processing described below as a preventative measure to attempt to prevent paging collision from occurring. Thus, in other portions of this disclosure, when referring to paging collisions, it is meant that collisions are occurring at the time and/or are expected to occur in the future.

In one aspect of the present disclosure, a multimode UE may measure a time difference between a SFN corresponding to a paging occasion of a WCDMA network to which it is registered and a SFN corresponding to a paging occasion of a TD-SCDMA network to which it is registered. In one example, as shown in the timing diagram of fig. 7, the SFN time difference is measured by subtracting SFN "y" in a TD-SCDMA cell from SFN "x" in a WCDMA cell, plus a frame boundary delay 710. Here, if the WCDMA frame boundary 720 is received earlier than the TD-SCDMA frame boundary 730, the frame boundary delay 710 is positive.

The shorter period (i.e., DRX cycle) of both techniques is defined as shown in equation (5):

DRX_cycle＝min{DRX_cycle_td，DRX_cycle_wcdma}(5)

an arbitrary paging occasion is selected in both systems and the time difference D between these time instances is calculated to monitor PICH, as shown in equation (6):

D＝(paging_occasion_wcdma-12ms-paging_occasiontd-p*10ms

SFN difference) mod DRX cycle (6)

The 12ms term appears in equation (6) because the start of WCDMAPICH is 12ms earlier than the start of PCH (see fig. 5). The factor p x 10ms occurs in equation (6) because the UE only monitors PICH with frame number p.

Therefore, the conflicting conditions in PICH monitoring are given by equation (7):

whether D is more than or equal to 0 and less than 10ms + M

Or

DRX_cycle-10ms-M＜D≤DRX_cycle (7)

Here, M is a margin of time for allowing RF tuning, acquisition, etc. to decode paging information in the handover RAT. The 10ms may be the maximum time offset between PICH frames of two RATs that have a collision in PICH monitoring.

In an aspect of the present disclosure, if a conflict condition exists in the paging monitoring of two different networks, as per equation (7), the processing for avoiding the conflict includes finding and handing over to a different NB of at least one network. This process takes advantage of the possibility that in e.g. wcdma rat, the frame number at which the paging indicator message is sent is different for different NBs.

Those skilled in the art will note that if the frames are aligned and the frame numbers are synchronized, i.e., identical across all NBs, then a collision condition may exist even after handover to other base stations. Here, however, even if the frame number at which the paging indicator message is sent is the same at two different base stations (e.g., 131, 259, etc. as given in the simplified example above), the frames do not have to be synchronized. That is, the frame numbers are typically not synchronized for different WCDMA base stations. For example, if the first base station transmits frame number 10 at time t, the second base station may transmit frame number 50 at time t. Thus, even if the paging indicator appears on the same frame schedule, it may still appear at different absolute times at different base stations.

The process includes finding candidate cells for which no paging collision condition exists. Before considering handover to a candidate cell, the candidate cell should have a signal characteristic (e.g. signal power, signal to interference ratio or any other suitable characteristic) that exceeds a threshold (e.g. a minimum value (or a maximum value as appropriate for the particular characteristic)). The selection includes changing a WCDMA cell, changing a TD-SCDMA cell, or changing both a WCDMA and TD-SCDMA cell. The final decision of which cell to select for cell reselection may be based on which cell has the best signal characteristics among the candidate cells, e.g., the cell with the highest power.

As previously mentioned, the detailed description herein provides details regarding multimode UEs in overlapping TD-SCDMA and WCDMA networks. However, those skilled in the art will appreciate that the processes described herein may be applied to other scenarios within the spirit and scope of the present disclosure. For example, the illustrated concept relies on a scenario where in a TD-SCDMA network, frame boundaries may be synchronized or aligned for different NBs, while SFNs may generally be unsynchronized or unaligned for different NBs; in WCDMA networks, neither the frame boundary nor the SFN is typically synchronized or aligned for different NBs. Thus, as described in detail below, cell reselection may occur in either network.

However, those skilled in the art will appreciate that in a CDMA2000 network, the timing of frames may be substantially synchronized for different base stations, and therefore, a multimode UE generally does not benefit from cell reselection to a different CDMA2000 base station. That is, for multimode UEs subscribed to a TD-SCDMA network and a CDMA2000 network, cell reselection may be performed for the TD-SCDMA network. Similarly, for a multimode UE subscribed to a WCDMA network and a CDMA2000 network, cell reselection may be made for the WCDMA network. For a multimode UE subscribed to a TD-SCDMA network, a WCDMA network, and a CDMA2000 network, cell reselection may be made for one or both of the TD-SCDMA network and/or the WCDMA network.

Finally, those skilled in the art will appreciate that LTE networks exhibit similar misalignment between paging indication frames for different enhanced nbs (enbs), and thus, for multimode UEs subscribed to any 3G network (e.g., TD-SCDMA, WCDMA, CDMA2000, etc.) and LTE networks, appropriate cell reselection may be made for TD-SCDMA, WCDMA, and/or LTE networks.

More specifically, an exemplary process for avoiding paging collision conditions according to one aspect of the present disclosure is illustrated in fig. 8. While details are provided assuming that a multi-mode UE is registered with TD-SCDMA RAT and WCDMARAT, those skilled in the art will appreciate that the ideas, concepts and procedures discussed herein may be equally applied to multi-mode UEs registered with any number of RATs, such as, but not limited to, TD-SCDMA, WCDMA, TD-CDMA, CDMA2000, 3GPP LTE, LTE advanced, and so forth, as discussed previously.

According to one aspect of the disclosure, at block 802, processing determines whether a conflict condition exists in paging monitoring of TD-SCDMA RAT and WCDMA RAT. In one example, the existence of a conflict condition is determined according to equation (7) above. If there is no conflict condition, the process exits and may be restarted immediately or later.

In various examples of processing according to the disclosed aspects, the branches in FIG. 8 beginning at blocks 804 and 816 may be performed together or may be performed alternately. In the exemplary process described below, for ease of description, it will be assumed that these two branches will be executed together.

At block 804, the process searches for a candidate cell in the TD-SCDMA network; at block 806, the process determines whether any candidate cells are found. Here, the candidate cells may include TD-SCDMA cells that meet one or more cell selection criteria. For example, determining candidate cells in a TD-SCDMA network may include: neighboring cells for which the Received Signal Code Power (RSCP) of the primary common control physical channel (P-CCPCH) is greater than a certain threshold (e.g., Qrxlevmin) are scanned for a particular NB. For meeting this criterion (i.e., RCSP)_cellQrxlevmin), the UE may measure the current WCDMA cell relative to the neighboring, RCSP_cellSFN between potential candidate TD-SCDMA cells > Qrxlevmin and determines if equation (7) above is false (i.e., if there is no paging collision condition with the current WCDMA cell). The UE may repeat blocks 804 and 806 until it collects all TD-SCDMA cells that meet these criteria as potential candidate TD-SCDMA cells for cell reselection.

If at least one cell is found as a potential candidate cell at block 806, the process continues to block 808 where the process selects the cell with the highest RSCP as a candidate for TD-SCDMA cell reselection. The candidate cell may be in the same location area as the current cell or in a different location area. However, if the candidate cell is within a different location area, then reselecting to the candidate cell, if it occurs, may also include registering with other location areas after performing cell reselection to the candidate cell.

Returning to block 816, the process searches for candidate cells in the WCDMA network; at block 818, the process determines whether any candidate cells are found. Similar to the process described above for TD-SCDMA networks, here the process finds potential candidate cells by: the RSCP of the scanned out common pilot channel (CPICH) is greater than a certain threshold (e.g., Qrxlevmin) and the signal-to-noise ratio E_c/N₀Neighbor cells above another threshold (e.g., Qqualmin) and determine if the previous equation (7) is false for these cells (i.e., if there is no paging collision condition with the current TD-SCDMA cell). The UE may repeat blocks 816 and 818 until it collects all WCDMA cells that meet these criteria as potential candidate WCDMA cells for cell reselection.

If at least one cell is found as a potential candidate cell at block 818, the process continues to block 820 where the process selects the cell with the highest RSCP as a candidate for WCDMA cell reselection. The candidate cell may be in the same location area as the current cell or in a different location area. However, if the candidate cell is within a different location area, then reselecting to the candidate cell, if it occurs, may also include registering with other location areas after performing cell reselection to the candidate cell.

If no candidate TD-SCDMA cell is found at block 806 and no candidate WCDMA cell is found at block 818, the algorithm fails to identify an alternate cell for cell reselection to resolve paging collisions. In this case, the process passes to block 826 and a contention resolution scheme, e.g., monitoring separate TD-SCDMA and WCDMA paging channels while suffering from the standard problems associated with paging collisions. That is, the UE maintains its registration with the current TD-SCDMA and WCDMA cells and monitors the paging indicator channel with collisions. As long as there is an actual collision, the UE may select any one RAT to listen for its respective paging indicator. However, the process may return to block 802 and continue searching for neighboring cells as previously described until a suitable cell without a paging collision condition is reselected.

However, if a candidate cell is found in block 808 or block 820 (but not in both blocks), then the neighboring cell in the corresponding TD-SCDMA or WCDMA network that is determined to be a candidate cell is a reselected cell. That is, at block 810, the process has determined a candidate TD-SCDMA cell. If, at block 810, the process determines that a candidate WCDMA cell has not been determined, the process passes to block 812 where cell reselection of a TD-SCDMA cell to the candidate TD-SCDMA cell is performed, thereby avoiding a collision condition. Similarly, at block 820, the process has determined candidate WCDMA cells. If, at block 822, the process determines that a candidate TD-SCDMA cell has not been determined, the process passes to block 824, where cell reselection of a WCDMA cell to the candidate WCDMA cell is performed, thereby avoiding a collision condition.

If candidate cells are found in both blocks 808 and 820, the process may select among candidate cells in a TD-SCDMA or WCDMA network for cell reselection by selecting a cell with a better RSCP (and in some cases using a value of the power offset (e.g., RSCP-offset) for the determination). This offset is useful because the performance of WCDMA networks and TD-SCDMA networks may be different, but their RSCP may be the same. This situation can be determined by field testing the respective downlink performance or by simulation. In some cases, the appropriate offset value may be predetermined and preset by the UE manufacturer. In some cases, the offset value may be adjusted in real time during operation. In other cases, the offset value may not be directly related to the downlink performance, but may be related to business decisions, e.g., selecting a TD-SCDMA network always prefers a WCDMA network even if the RSCP of the WCDMA network is equal to or greater than the RSCP of the TD-SCDMA network by a certain threshold offset value.

Thus, if processing determines that there are WCDMA candidate cells in addition to the TD-SCDMA candidate cells determined at block 808, processing determines that there are WCDMA candidate cells at block 810; alternatively, if processing determines that there are TD-SCDMA candidate cells in block 822 in addition to the WCDMA candidate cells determined in block 820, processing passes to block 814 where the corresponding candidate cell with the largest RSCP-offset value is determined. If the TD-SCDMA candidate cell has the maximum value, the process passes to block 812, where cell reselection to the TD-SCDMA candidate cell is performed. If the WCDMA candidate cell has the maximum value, the process passes to block 824, where cell reselection to the WCDMA candidate cell is performed.

Several schemes of telecommunication systems have been given with reference to TD-SCDMA systems. Those skilled in the art will readily appreciate that the various aspects described throughout this disclosure may be extended to other telecommunications systems, network architectures, and communication standards. For example, the 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), enhanced high speed packet Access (HSPA +) and TD-CDMA. The various aspects may also be extended to systems that use the following techniques: long Term Evolution (LTE) (in FDD, TDD, or both), LTE-advanced (LTE-a) (in FDD, TDD, or both), 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 to extend to other suitable systems. The actual telecommunications standard, network architecture, and/or communication standard used will depend on the specific application and overall design constraints imposed on the system.

Several processors have been described in connection with various apparatus 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 depends upon the particular application and overall design constraints imposed on the system. For example, a processor, any portion of a processor, or any combination of processors presented in this disclosure may be implemented with a microprocessor, a microcontroller, a Digital Signal Processor (DSP), a Field Programmable Gate Array (FPGA), a Programmable Logic Device (PLD), a state machine, gated logic, discrete hardware circuitry, 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 in software for execution by a microprocessor, microcontroller, DSP, or other suitable platform.

Software should be construed broadly to mean instructions, instruction sets, code segments, program code, programs, subprograms, software modules, 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 other terminology. The software may reside on a computer readable medium. By way of example, a computer-readable medium may include memory such as a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., Compact Disk (CD), Digital Versatile Disk (DVD)), a smart card, a flash memory device (e.g., card, stick, key disk), Random Access Memory (RAM), Read Only Memory (ROM), programmable ROM (prom), erasable prom (eprom), electrically erasable prom (eeprom), a register, or a removable disk. While the memory is shown as separate from the processor in the various aspects presented throughout this disclosure, the memory may be internal to the processor (e.g., as a cache or register).

The computer readable medium may be embodied in a computer program product. For example, the computer program product may include a computer-readable medium in a packaging material. Those skilled in the art will recognize how best to implement the functionality presented throughout this disclosure depends on the particular application and overall design constraints imposed on the overall system.

It should be understood that the specific order or hierarchy of steps in the methods disclosed is an illustration of exemplary processing. It should be understood that the specific order or hierarchy of steps in the methods may be rearranged based on design preferences. 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.

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 as well. Thus, the following claims are not intended to be limited to the versions shown herein, but are to be accorded the full scope consistent with the language 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. The term "some" refers to one or more unless specifically stated otherwise. A phrase referring to "at least one of" a list of items refers to any combination of items, including a single element. For example, "at least one of a, b, or c" is meant to include: 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 appended claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. All claim elements are not to be read under the 35u.s.c. § 112, sixth paragraph, unless the element is explicitly recited by the phrase "module for … …", or in a method claim the element is recited by the phrase "step for … …".

Claims (52)

1. A method of wireless communication, comprising:

determining the existence of a paging collision between a first cell of a first network and a second cell of a second network;

determining at least one candidate cell in one of the first network or the second network to avoid the paging collision; and

performing cell reselection from one of the first cell or the second cell to the candidate cell.

2. The method of claim 1, wherein a signal corresponding to the at least one candidate cell has a signal characteristic above a predetermined threshold.

3. The method of claim 2, wherein the signal characteristic is at least one of a signal power or a signal-to-interference ratio.

4. The method of claim 2, wherein the at least one candidate cell is within the same location area as the first cell when the at least one candidate cell is in the first network and the at least one candidate cell is within the same location area as the second cell when the at least one candidate cell is in the second network.

5. The method of claim 2, wherein when the at least one candidate cell is not within the same location area as either the first cell in the first network or the second cell in the second network, the method further comprises: after performing cell reselection from one of the first cell or the second cell to the candidate cell, registering within a location area corresponding to the at least one candidate cell.

6. The method of claim 1, wherein the first network is a WCDMA network and the second network is a TD-SCDMA network.

7. The method of claim 1, wherein the first network is a TD-SCDMA network and the second network is a WCDMA network.

8. The method of claim 1, wherein the at least one candidate cell comprises a plurality of cells, and determining at least one candidate cell in one of the first network or the second network comprises: selecting a cell having a highest received signal code power from the plurality of cells.

9. The method of claim 1, wherein the at least one candidate cell is a first cell in the first network, and further comprising:

determining a second candidate cell in the second network; and

selecting between a first candidate cell and a second candidate cell by determining which of the first candidate cell and the second candidate cell has a larger signal parameter than the other of the first candidate cell and the second candidate cell.

10. The method of claim 9, wherein the signal parameter comprises a received signal code power.

11. The method of claim 10, wherein the signal parameter further comprises a value of a power offset.

12. The method of claim 11, wherein the power offset comprises a calibration value corresponding to a performance analysis of the first network and the second network.

13. The method of claim 11, wherein the power offset comprises a preset value corresponding to a preference of one of the first network or the second network.

14. An apparatus for wireless communication, comprising:

means for determining the existence of a paging collision between a first cell of a first network and a second cell of a second network;

means for determining at least one candidate cell in one of the first network or the second network to avoid the paging collision; and

means for performing cell reselection from one of the first cell or the second cell to the candidate cell.

15. The apparatus of claim 14, wherein a signal corresponding to the at least one candidate cell has a signal characteristic above a predetermined threshold.

16. The apparatus of claim 15, wherein the signal characteristic is at least one of a signal power or a signal-to-interference ratio.

17. The apparatus of claim 15, wherein the at least one candidate cell is within a same location area as the first cell when the at least one candidate cell is in the first network and the at least one candidate cell is within a same location area as the second cell when the at least one candidate cell is in the second network.

18. The apparatus of claim 15, wherein when the at least one candidate cell is not within a same location area as either the first cell in the first network or the second cell in the second network, the apparatus further comprises: means for registering within a location area corresponding to the at least one candidate cell after performing cell reselection from one of the first cell or the second cell to the candidate cell.

19. The apparatus of claim 14, wherein the first network is a WCDMA network and the second network is a TD-SCDMA network.

20. The apparatus of claim 14, wherein the first network is a TD-SCDMA network and the second network is a WCDMA network.

21. The apparatus of claim 14, wherein the at least one candidate cell comprises a plurality of cells, and the means for determining at least one candidate cell in one of the first network or the second network comprises: means for selecting a cell from the plurality of cells having a highest received signal code power.

22. The apparatus of claim 14, wherein the at least one candidate cell is a first cell in the first network, and further comprising:

means for determining a second candidate cell in the second network; and

means for selecting between a first candidate cell and a second candidate cell by determining which of the first candidate cell and the second candidate cell has a larger signal parameter than the other of the first candidate cell and the second candidate cell.

23. The apparatus of claim 22, wherein the signal parameter comprises a received signal code power.

24. The apparatus of claim 23, wherein the signal parameter further comprises a value of a power offset.

25. The apparatus of claim 24, wherein the power offset comprises a calibration value corresponding to a performance analysis of the first network and the second network.

26. The apparatus of claim 24, wherein the power offset comprises a preset value corresponding to a preference of one of the first network or the second network.

27. A computer program product, comprising:

a computer-readable medium comprising code for:

determining the existence of a paging collision between a first cell of a first network and a second cell of a second network;

determining at least one candidate cell in one of the first network or the second network to avoid the paging collision; and

performing cell reselection from one of the first cell or the second cell to the candidate cell.

28. The computer program product of claim 27, wherein a signal corresponding to the at least one candidate cell has a signal characteristic above a predetermined threshold.

29. The computer program product of claim 28, wherein the signal characteristic is at least one of a signal power or a signal-to-interference ratio.

30. The computer program product of claim 28, wherein the at least one candidate cell is within a same location area as the first cell when the at least one candidate cell is in the first network and the at least one candidate cell is within a same location area as the second cell when the at least one candidate cell is in the second network.

31. The computer program product of claim 28, wherein when the at least one candidate cell is not within the same location area as neither the first cell in the first network nor the second cell in the second network, the computer-readable medium further comprises code for registering within a location area corresponding to the at least one candidate cell after performing cell reselection from one of the first cell or the second cell to the candidate cell.

32. The computer program product of claim 27, wherein the first network is a WCDMA network and the second network is a TD-SCDMA network.

33. The computer program product of claim 27, wherein the first network is a TD-SCDMA network and the second network is a WCDMA network.

34. The computer program product of claim 27, wherein the at least one candidate cell comprises a plurality of cells, and the code for determining at least one candidate cell in one of the first network or the second network comprises: code for selecting a cell from the plurality of cells having a highest received signal code power.

35. The computer program product of claim 27, wherein the at least one candidate cell is a first cell in the first network, and the computer-readable medium further comprises code for:

determining a second candidate cell in the second network; and

selecting between a first candidate cell and a second candidate cell by determining which of the first candidate cell and the second candidate cell has a larger signal parameter than the other of the first candidate cell and the second candidate cell.

36. The computer program product of claim 35, wherein the signal parameter comprises a received signal code power.

37. The computer program product of claim 36, wherein the signal parameter further comprises a value of a power offset.

38. The computer program product of claim 37, wherein the power offset comprises a calibration value corresponding to a performance analysis of the first network and the second network.

39. The computer program product of claim 37, wherein the power offset comprises a preset value corresponding to a preference of one of the first network or the second network.

40. An apparatus for wireless communication, comprising:

at least one processor; and

a memory coupled to the at least one processor,

wherein the at least one processor is configured to:

determining the existence of a paging collision between a first cell of a first network and a second cell of a second network;

determining at least one candidate cell in one of the first network or the second network to avoid the paging collision; and

performing cell reselection from one of the first cell or the second cell to the candidate cell.

41. The apparatus of claim 40, wherein a signal corresponding to the at least one candidate cell has a signal characteristic above a predetermined threshold.

42. The apparatus of claim 41, wherein the signal characteristic is at least one of a signal power or a signal-to-interference ratio.

43. The apparatus of claim 41, wherein the at least one candidate cell is within a same location area as the first cell when the at least one candidate cell is in the first network and the at least one candidate cell is within a same location area as the second cell when the at least one candidate cell is in the second network.

44. The apparatus of claim 41, wherein when the at least one candidate cell is not within the same location area as either the first cell in the first network or the second cell in the second network, the at least one processor is further configured to: after performing cell reselection from one of the first cell or the second cell to the candidate cell, registering within a location area corresponding to the at least one candidate cell.

45. The apparatus of claim 40, wherein the first network is a WCDMA network and the second network is a TD-SCDMA network.

46. The apparatus of claim 40, wherein the first network is a TD-SCDMA network and the second network is a WCDMA network.

47. The apparatus of claim 40, wherein the at least one candidate cell comprises a plurality of cells, and determining at least one candidate cell in one of the first network or the second network comprises: selecting a cell having a highest received signal code power from the plurality of cells.

48. The apparatus of claim 40, wherein the at least one candidate cell is a first cell in the first network, and the at least one processor is further configured to:

determining a second candidate cell in the second network; and

selecting between a first candidate cell and a second candidate cell by determining which of the first candidate cell and the second candidate cell has a larger signal parameter than the other of the first candidate cell and the second candidate cell.

49. The apparatus of claim 48, wherein the signal parameter comprises a received signal code power.

50. The apparatus of claim 49, wherein the signal parameter further comprises a value of a power offset.

51. The apparatus of claim 50, wherein the power offset comprises a calibration value corresponding to a performance analysis of the first network and the second network.

52. The apparatus of claim 50, wherein the power offset comprises a preset value corresponding to a preference of one of the first network or the second network.