Patent Application
20150304977
1. Field
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to improving a selection of timing advance for uplink synchronization.
2. Background
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.
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.
The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.
A user equipment (UE) may reducing the interference and improve the random access of the multiple users in the network. In some instances, the UE adjusts a timing advance and/or guard period values to reduce the interference experienced in a particular guard period. The adjustment is based on selecting a timing advance parameter for uplink synchronization based at least in part on an interference distribution in a guard period of a frame in a TD-SCDMA network.
A method for improving a selection of timing advance for uplink synchronization is provided. The method includes receiving an interference distribution information. Additionally, the method includes selecting a timing advance parameter for uplink synchronization based at least in part on the interference distribution information. Furthermore, the method includes communicating according to the selected timing advance parameter.
In another aspect, an apparatus for improving a selection of timing advance for uplink synchronization is provided. The apparatus includes a processor configured to receive an interference distribution information. Additionally, the processor is configured to select a timing advance parameter for uplink synchronization based at least in part on the interference distribution information. Furthermore, processor is configured to communicate according to the selected timing advance parameter.
In another aspect, an apparatus for improving a selection of timing advance for uplink synchronization is provided that includes means for receiving an interference distribution information. Additionally, the apparatus includes means for selecting a timing advance parameter for uplink synchronization based at least in part on the interference distribution information. Furthermore, the apparatus includes means for communicating according to the selected timing advance parameter.
In yet another aspect, a computer-readable media for improving a selection of timing advance for uplink synchronization is provided that includes machine-executable code for receiving an interference distribution information. Additionally, the code may be executable for selecting a timing advance parameter for uplink synchronization based at least in part on the interference distribution information. Furthermore, the code may be executable for communicating according to the selected timing advance parameter.
To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents.
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.
Turning now to
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.
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.
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.
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.
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.
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 (
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 (
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 (
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 timing advance selection module 391 which, when executed by the controller/processor 390, configures the UE 350 for inter-RAT/inter-frequency measurements. 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.
Some TD-SCDMA protocols provide methods to advance the uplink transmission timing. First, in a random access procedure, the UE sends synchronization uplink (SYNC_UL) codes on the Uplink Pilot Time Slot (UpPTS), and a node B measures and sends to the UE the timing information on the Fast Physical Access Channel (FPACH). The Fast Physical Access Channel message format may be configured such that the received starting position of the UpPCH parameter may be used to initially determine the timing advance value at the UE.
The first UpPTS 412A contains a synchronization uplink sequence (SYNC-UL) of 128 chips and the second guard period 410A is 32 chips. The SYNC-UL in TD-SCDMA systems is used for identification in a random access procedure. The guard period is a switching point. For example, the guard periods 408A and 408B are the switching point from transmitting to receiving within the subframe structure 402 or 404. The duration of the first guard period 408A is 96 chips, from which a basic cell radius of 11.2 kilometers (km) may be derived. Each guard period 408A, 408B, 410A or 410B should be long enough to avoid uplink and downlink interference. For example, the transmission of the second UpPTS 412B can be advanced up to 48 chips from the second DwPTS 406B while maintaining a second guard period 408B of 48 chips that is long enough to reduce the uplink and downlink interference. The timeline associated with second guard period 408B may be deemed a base timeline of a node B. Control of uplink transmission to coordinate arrival time at the node B may be performed by the UE to properly advance its uplink transmission of a 10-ms long frame relative to the received downlink 10-ms frame time. This advance is called a timing advance (TA).
In TD-SCDMA, uplink and downlink transmission is synchronized at the node B. As shown in
Further, the timing advance associated with UE 1 may correspond to the timing advance of the base timeline of NB 0 that that may correspond to a guard period of 48 chips. Because multiple user equipments and node Bs access NB 0 the guard periods for each of those devices may be subject to interference caused by uplink and downlink transmission associated with the other user equipments and node Bs.
Offered is a method and system for reducing the interference and improve the random access of the multiple users in the network. One aspect of the present disclosure analyzes interference distribution between the first guard period between the DwPTS and the UpPTS and selects a timing advance based on the interference distribution. Selecting a better initial timing advance may reduce interference in the guard period and improve the signal to noise ratio of the SYNC-UL, thereby improving UE performance.
Referring to
In an aspect, within the UE 914 resides a call processing component 940. The call processing component 940 may be configured, among other things, to include a receiving component 942 capable of receiving a interference distribution information. For example, receiving component 942, residing in the call processing component 940 of UE 914, is configured for receiving the interference distribution information 943 from network 912 over wireless link 925.
In another aspect, the call processing component 940 may be configured to include a selecting component 944 configured for selecting a timing advance parameter for uplink synchronization based at least in part on the interference distribution information. For example, selecting component 944 is configured for selecting the timing advance parameter 945 for uplink synchronization based at least in part on the interference distribution information 943.
In another aspect, the call processing component 940 may be configured to include a communicating component 946 configured for communicating according to the selected timing advance parameter. For example, communicating component 946 is configured to allow UE 914 to communicate with network 912 according to the selected timing advance parameter 945.
In an aspect, for example, UE 114 of wireless communication system 900 may be executed by UE 350 (
In this aspect, transmitting based on the reduced timing advance associated with SYNC-UL 3 may be more desirable than transmitting based on the timing advance associated with SYNC-UL 2 and SYNC-UL 1 because of a reduced signal to noise ratio associated with SYNC-UL 3 in the first guard period 1008A. An example illustration of the signal to noise power analysis is as follows:
In one aspect, the timing advance is selected based on the interference distribution. Thus, the interference distribution between the 96 chips guard period between the DwPTS and the UpPTS may be analyzed. Based on the interference distribution a timing advance may be selected to accommodate the interference. In one aspect, the interference distribution may be analyzed independent of the UE. In this aspect, the UE may be configured to receive the interference distribution information based on the interference distribution analysis. A timing advance may be selected based on the received interference distribution information.
In one aspect, a node B measures the interference between the 96 chips guard period and broadcast the interference information to the UE. The UE may select the timing advance based on the broadcasted interference information to reduce interference for transmitting SYNC-UL.
In another aspect, a UE may also listen for potential interference during an otherwise inactive period. The UE may take the identified interference during this period and then base a timing advance on this interference distribution.
In one aspect, the guard period of 48+16 chips is divided into N discrete sections with each section including 64/N chips. One or more of the discrete sections may be selected as the initial timing advance and the random access success/failure rate may be monitored based on the selection of each of the one or more timing advances. For example, in defining randomization, suppose there are two sections, such as 48 chips and 24 chips, where the success rate of 48 chips is 1 and that of 24 chips is 0.1. If after selecting the initial timing advance of 48 chips fails, the success rate is updated by a filter (e.g. by a filter coefficient of 0.1). Thereafter, the success rate of selecting a timing advance of 48 chips will become 0.9. Indeed, even if the success rate of selecting 48 chips (=0.9) is higher than that of selecting 24 chips (=0.1), the next timing advance chosen will be 24. As such, all the possible timing advances are chosen based on the success rate before the timing advance already selected is chosen. Other forms of randomization may include coin-tossing or sequential try.
A timing advance associated with the one or more discrete sections may also be selected based on the result of the monitoring. For example, the timing advance of the discrete section with a better success rate may be selected for transmitting SYNC-UL.
In one aspect, the interference distribution in the 96 chips guard period may be measured during operation or field testing of the UE. The measurement results may be implemented into a predefined timing advance selection table including one or more timing advances. The random access success rate of each timing advance may be indicated in the predefined timing advance selection table. The timing advance may be selected from the predefined timing advance selection table for future use. In one aspect of the disclosure, the interference may be measured when the UE is in the idle mode. An average interference distribution may be generated after measuring over a period of time. In a random access communication, a UE may select sequentially or randomly select one or more timing advances on the predefined timing advance selection table until the SyncUL procedure succeeds. It should be noted that both pre-defined timing advance selection table are dynamically updated and saved during the above operation.
At 1204, selecting a timing advance parameter for uplink synchronization based at least in part on the interference distribution information occurs. For example, after receiving the interference distribution information 943 from network 912, selecting component 944 of UE 914 is configured for selecting the timing advance parameter 945 for uplink synchronization to network 912 based at least in part on the interference distribution information 943.
At 1206, communicating according to the selected timing advance parameter occurs. For example, after selecting the timing advance parameter 945 for uplink synchronization to network 912, communicating component 946 is configured to allow UE 914 to communicate with network 912 according to the selected timing advance parameter 945.
In an aspect, for example, UE 114 of executing method 1200 may be executed by UE by UE 350 (
The apparatus includes a timing advance selection system 1314 coupled to a transceiver 1330. The transceiver 1330 is coupled to one or more antennas 1320. The transceiver 1330 enables communicating with various other apparatus over a transmission medium. The timing advance selection system 1314 includes a processor 1322 coupled to a computer-readable medium 1326. The processor 1322 is responsible for general processing, including the execution of software stored on the computer-readable medium 1326. The software, when executed by the processor 1322, causes the timing advance selection system 1314 to perform the various functions described for any particular apparatus. The computer-readable medium 1326 may also be used for storing data that is manipulated by the processor 1322 when executing software.
The timing advance selection system 1314 includes the selecting module 1302 for selecting a timing advance parameter for uplink synchronization based at least in part on an interference distribution information in a guard period of a frame in a TD-SCDMA network. The timing advance selection system 1314 includes the communicating module 1304 for communicating according to the selected timing advance parameter. The modules may be software modules running in the processor 1322, resident/stored in the computer-readable medium 1326, one or more hardware modules coupled to the processor 1322, or some combination thereof. The timing advance selection system 1314 may be a component of the UE 350 and may include the memory 392, and/or the controller/processor 390.
In one configuration, an apparatus such as a UE is configured for wireless communication including means for selecting. In one aspect, the above means may be the controller/processor 390, the memory 392, the receive frame processor 360, the transmit frame processor 382, the receive processor 370, the transmit processor 380, the timing advance selection module 391, selecting module 1302, and/or the timing advance selection system 1314 configured to perform the functions recited by the aforementioned means. In another aspect, the aforementioned means may be a module or any apparatus configured to perform the functions recited by the aforementioned means.
In one configuration, an apparatus such as a UE is configured for wireless communication including means for selecting. In one aspect, the above means may be the controller/processor 390, the memory 392, the timing advance selection module 391, selecting module 1304, and/or the timing advance selection system 1314 configured to perform the functions recited by the aforementioned means. In another aspect, the aforementioned means may be a module or any apparatus configured to perform the functions recited by the aforementioned means.
Several aspects of a telecommunications system has been presented with reference to TD-SCDMA systems. 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.
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.
Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside on a computer-readable medium. A computer-readable medium may include, by way of example, memory such as a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., compact disc (CD), digital versatile disc (DVD)), a smart card, a flash memory device (e.g., card, stick, key drive), random access memory (RAM), read only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), a register, or a removable disk. Although memory is shown separate from the processors in the various aspects presented throughout this disclosure, the memory may be internal to the processors (e.g., cache or register).
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.
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.
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.”
| Number | Date | Country | Kind |
|---|---|---|---|
| PCT/CN2012/086277 | Dec 2012 | CN | national |
The present Application for Patent claims priority to PCT Application No. PCT/CN/2012/086277 entitled “TIMING ADVANCE SELECTION FOR SYNCHRONIZED UPLINK TRANSMISSION” filed Dec. 10, 2012, in the Receiving Office of China (RO/CN), and assigned to the assignee hereof and hereby expressly incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2013/085887 | 10/24/2013 | WO | 00 |
