+

WO2006067657A1 - Procede et appareil de recherche de cellule dans un systeme de communication sans fil - Google Patents

Procede et appareil de recherche de cellule dans un systeme de communication sans fil Download PDF

Info

Publication number
WO2006067657A1
WO2006067657A1 PCT/IB2005/054115 IB2005054115W WO2006067657A1 WO 2006067657 A1 WO2006067657 A1 WO 2006067657A1 IB 2005054115 W IB2005054115 W IB 2005054115W WO 2006067657 A1 WO2006067657 A1 WO 2006067657A1
Authority
WO
WIPO (PCT)
Prior art keywords
sequence
synchronization
initial synchronization
signal
mobile terminal
Prior art date
Application number
PCT/IB2005/054115
Other languages
English (en)
Inventor
Yan Li
Xia Zhu
Original Assignee
Koninklijke Philips Electronics N.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips Electronics N.V. filed Critical Koninklijke Philips Electronics N.V.
Publication of WO2006067657A1 publication Critical patent/WO2006067657A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H04B1/707—Spread spectrum techniques using direct sequence modulation
    • H04B1/7073—Synchronisation aspects
    • H04B1/7083—Cell search, e.g. using a three-step approach
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B2201/00—Indexing scheme relating to details of transmission systems not covered by a single group of H04B3/00 - H04B13/00
    • H04B2201/69—Orthogonal indexing scheme relating to spread spectrum techniques in general
    • H04B2201/707—Orthogonal indexing scheme relating to spread spectrum techniques in general relating to direct sequence modulation
    • H04B2201/70701—Orthogonal indexing scheme relating to spread spectrum techniques in general relating to direct sequence modulation featuring pilot assisted reception

Definitions

  • the present invention relates to a wireless communication system, and more particularly, to a method of cell search for a mobile terminal in a wireless communication system and the apparatus therefor.
  • CDMA cell search operation needs to be performed when a mobile terminal establishes initial synchronization or a cell handover is being carried out due to the movement of the mobile terminal.
  • wide-band code division multiple access/frequency division duplex WCDMA/FDD
  • WCDMA/FDD wide-band code division multiple access/time division duplex
  • WCDMA/TDD time division synchronization code division multiple access
  • TD- SCDMA time division synchronization code division multiple access
  • some special synchronization signals are applied, e.g. the synchronization channel (SCH) in WCDMA and the downlink synchronization signal sequence (SYNC_DL) in TD-SCDMA.
  • SCH synchronization channel
  • SYNC_DL downlink synchronization signal sequence
  • Fig. 1 is a block diagram showing the basic structure of adopting a correlator to implement cell search in a mobile terminal.
  • Synchronization code generator 10 generates local synchronization code, which is sent to correlator 12 together with a received signal.
  • Correlator 12 comprises multiplier 122 and integrator 121. Thanks to the autocorrelation characteristic of the synchronization codes, integrator 121 will output a peak value if the synchronization code generated locally matches the received signal (i.e. having the same signal sequence and the same phase). Otherwise, correlator 12 will output a smaller value.
  • Controller 11 is used for controlling the sequence and phase of the local synchronization code.
  • correlator 12 To acquire the output peak value of correlator 12, correlator 12 must scan all possible synchronization code sequences and phases.
  • SYNC_DL is a system predetermined PN sequence of 64 chips, having at most 32 possible choices, the SYNC_DL of adjacent cells in the system are different from each other, while the SYNC_DL in non-adjacent cells could be reused.
  • the search of SYNC_DL is performed in a subframe.
  • Fig. 2 shows a standard subframe structure of TD- SCDMA. The length of subframe is 5ms, i.e. 6400 chips.
  • Each subframe is divided into 7 main time slots (TS0-TS6) and 3 special time slots: downlink pilot time slots (DwPTS) of 96 chips, guard period (GP) of 96 chips and uplink pilot time slots (UpPTS).
  • the length of a main time slot is 0.675ms, i.e. 864 chips.
  • the last 16 chips function as a guard period (GP).
  • One subframe has 6400 chips, which means that before the position of SYNC_DL in the subframe is determined, the phase of SYNC_DL may possibly be one of at least 6400 phases. As a result, totally 302800 (6400x32) correlation operations are needed to reach a correct SYNC_DL sequence and phase in a cell search, thus resulting in rather high complexity and long time of cell search.
  • DwPTS could be used as the pilot and synchronization channel of a downlink, which is transmitted at full power by a base station and consists of a SYNC_DL of 64 chips and a GP of 32 chips.
  • UpPTS could be used as the pilot and synchronization channel of a uplink, and usually consists of a SYNC_UP of 128 chips and a GP of 32 chips, wherein GP is used as the base station's switching point from transmission to reception, having a time length of 75 ⁇ s (96 chips).
  • GP the base station's switching point from transmission to reception
  • 75 ⁇ s 75 ⁇ s
  • the transmitters of base stations and mobile terminals will all maintain silent status in these GPs, i.e. do not transmit signals. This shows a power depression on the power pulse of a subframe of TD-SCDMA system during the GPs.
  • a SYNC_DL is required to be transmitted at full power level, which means that the intensity of SYNC_DL is usually greater than that of noises and thus the SYNC_DL can be detected. Furthermore, in a subframe of TD-SCDMA, the power pulse of the 64 chips SYNC_DL appears only once, so a coarse synchronization could be established by searching this unique power pulse of the 64 chips SYNC_DL.
  • a fast cell search method which comprises: obtaining a coarse time synchronization first through SYNC_DL power pulse search, then opening a time search window based on this coarse time synchronization, and searching SYNC_DL in this time search window in a traditional correlation manner.
  • a traditional correlation search will be limited to a very narrow time window instead of the entire time period of a subframe, and thereby reducing correlation calculation.
  • An object of the present invention is to provide a method of fast cell search for a mobile terminal in a wireless communication system and the apparatus therefor.
  • a mobile terminal in accordance with the present invention, which comprises: first, performing coarse time synchronization on an initial synchronization sequence in a received signal to obtain a coarse time parameter of the initial synchronization sequence; next, based on the coarse time parameter, correlating, within a corresponding coarse time range, signal sequences in a segment of a specific signal sequence which possibly conform to the initial synchronization sequence respectively with signal sequences at the corresponding positions in another segment of the specific signal sequence to acquire corresponding correlation results; then comparing the correlation results to determine an accurate time parameter of the initial synchronization sequence; in the end, determining the initial synchronization sequence based on the accurate time parameter.
  • Fig. 1 is a block diagram of some modules of a traditional fast cell search apparatus for mobile terminal
  • Fig. 2 is the standard subframe structure of TD-SCDMA system
  • Fig. 3 is a flow chart of SYNC_DL synchronization of fast cell search for mobile terminal in accordance with the present invention
  • Fig. 4 is a schematic diagram of performing correlation calculation on SYNC_DL in adjacent subframes
  • Fig. 5 is a block diagram of modules of a fast cell search apparatus for mobile terminal in accordance with the present invention.
  • Fig. 6 is a schematic diagram of adopting dichotomy for determining a SYNC_DL sequence.
  • a method of fast cell search for mobile terminal comprises: first receiving signals (step
  • step SIlO coarse time synchronization
  • the method being adopted therein could be the solution provided by No. '459 patent application, or the solution provided by other traditional techniques.
  • a search range needed for performing SYNC_DL time synchronization is reduced to a rather small coarse range around SYNC_DL.
  • supposing tro represents the time position of SYNC_DL chips, then [Ww, t r o+w] will represent the obtained coarse time range of SYNC_DL after coarse time synchronization.
  • step S 120 the correlation calculations between signal sequences at the possible time parameter positions of SYNC_DL in the subframe and signal sequences at the same positions in adjacent subframe are performed (step S 120).
  • the specific algorithm is as below:
  • R 1 (t)x(t + 6400T c ), _ w ⁇ i ⁇ w (1)
  • T c represents code rate
  • x(t) represents the received signal.
  • the above procedure is equivalent to respectively selecting, in said two adjacent subframes, two time windows whose lengths are both 64 chips, but there is always a distance of one subframe time length (i.e. 6400T c ) therebetween.
  • the two time windows slide within the range [Ww, W-w], and at the same time, correlation calculations of signal sequences that correspond to the two time windows are respectively performed during the sliding procedure.
  • FIG. 4 The schematic diagram concerning the correlation calculation of SYNC_DL in adjacent subframes is illustrated in Fig. 4, wherein the correlation calculation could be referred to as autocorrelation calculation because the correlation calculation is performed between sequences at the same positions in two adjacent subframes of the received signal. It could be learned from the above algorithm formula (1) that the autocorrelation calculation is performed 2w+l times in total within the range [-w, w].
  • step S 130 an accurate time synchronization of SYNC_DL can be obtained based on a peak value acquired by performing correlation calculation within said range (step S 130), the specific algorithm is as below:
  • step S 120 and step S 130 the sliding correlation operation also needs to be performed only once within the above range because it is only for determining SYNC_DL time parameter, without having to know the accurate sequence of SYNC_DL.
  • the correlation operations between the signal sequence at said position and 32 kinds of possible SYNC_DL sequences are directly performed, and the accurate SYNC_DL sequence in the received signal can be determined from a peak value of the correlation results (step S 140), thus achieving SYNC_DL synchronization and completing cell search.
  • Fig. 5 is a block diagram of a fast cell search apparatus for mobile terminal according to an embodiment of the present invention.
  • the search apparatus comprises coarse synchronization module 100, subframe delay module 200, autocorrelation calculation module 300, accurate synchronization module 400, 32 matching filters
  • coarse time synchronization is performed on a received signal by the coarse synchronization module 100.
  • subframe delay module 200 is used to delay the signal sequence at a possible time parameter position of
  • SYNC_DL in a subframe by a length of one subframe (i.e. delay by 5ms).
  • the delayed signal sequence and the signal sequence at the same position of next adjacent subframe are sent to autocorrelation calculation module 300 for correlation calculation.
  • accurate synchronization module 400 finds a peak value from the results of correlation calculations outputted from autocorrelation calculation module 300 so as to determine an accurate SYNC_DL time parameter.
  • the signal sequence at corresponding position in subframe is inputted to 32 parallel matching filters 501-532, and its correlation operations with 32 kinds of possible SYNC_DL sequences are performed.
  • the correlation results are inputted to identification module 600. If identification module 600 finds a peak value of the correlation results, then the SYNC_DL sequence that is used to generate said peak value is exactly the SYNC_DL sequence in the received signal.
  • Fig. 6 is a schematic diagram of adopting dichotomy for determining SYNC_DL sequence.
  • the signal sequence whose time parameter has been determined i.e. the unknown SYNC_DL sequence
  • SD_GP1 is the accumulation of the first 16 sequences in the 32 possible SYNC_DL sequences
  • SD_GP2 is the accumulation of the last 16 sequences.
  • the correlation calculation value between SD_GP1 and the unknown SYNC_DL sequence is greater than the correlation calculation value between SD_GP2 and the unknown SYNC_DL sequence, that means the kind of the SYNC_DL sequence in the received signal is one of the first 16 SYNC_DL sequences.
  • the first 16 SYNC_DL sequences are divided into two groups: first 8 sequences and last 8 sequences, then either group is correlated with the unknown SYNC_DL sequence, and then select the group of sequences having greater correlation value to repeat the above operation.
  • the accurate SYNC_DL sequence in the received signal can be determined, wherein the sequences for correlation in each group are derived from the following formulae:
  • a sliding correlation operation is first performed on two adjacent subframes to perform accurate time synchronization, and then the accurate SYNC_DL sequence is determined.
  • Such a synchronization method effectively reduces the calculation amount and the time consumed as compared with traditional techniques that perform sliding correlation operations 32 times.
  • the present invention could also be applied to other wireless communication systems as long as the initial synchronization sequences of the wireless communication systems could obtain coarse time synchronization through such manners as power pulse search, while the initial synchronization sequence could either be SYNC_DL, or other types of pilot sequence signals.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)

Abstract

L'invention concerne un procédé de recherche de cellule rapide pour un terminal mobile ainsi qu'un appareil à cet effet. Le terminal mobile exécute d'abord une synchronisation temporelle approximative sur une séquence de synchronisation initiale dans un signal reçu, p. ex. la séquence de synchronisation descendante (SYNC_DL) dans un système TD-SCDMA, pour obtenir un paramètre temporel approximatif de la SYNC_DL. Ensuite, ledit terminal exécute des calculs de corrélation entre des séquences de signaux éventuellement conformes à la SYNC_DL dans des sous-trames adjacentes sur la base du paramètre temporel approximatif et détermine un paramètre temporel précis de la SYNC_DL à partir d'une valeur de crête des résultats de calculs de corrélation. Enfin, le terminal mobile détermine la séquence SYNC_DL dans le signal reçu par ce terminal mobile sur la base du paramètre temporel précis, effectuant ainsi la synchronisation SYNC_DL et terminant la recherche de cellule.
PCT/IB2005/054115 2004-12-24 2005-12-08 Procede et appareil de recherche de cellule dans un systeme de communication sans fil WO2006067657A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN200410104488 2004-12-24
CN200410104488.9 2004-12-24

Publications (1)

Publication Number Publication Date
WO2006067657A1 true WO2006067657A1 (fr) 2006-06-29

Family

ID=36127389

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2005/054115 WO2006067657A1 (fr) 2004-12-24 2005-12-08 Procede et appareil de recherche de cellule dans un systeme de communication sans fil

Country Status (1)

Country Link
WO (1) WO2006067657A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008022591A1 (fr) * 2006-08-18 2008-02-28 Huawei Technologies Co., Ltd. Procédé de commande de l'identification des cellules dans un système lte et appareil à cet effet
CN102281082A (zh) * 2010-06-13 2011-12-14 中兴通讯股份有限公司 Td-scdma中单倍采样数据的下行同步码确认方法和装置
CN101453237B (zh) * 2007-12-05 2012-09-05 大唐移动通信设备有限公司 搜索下行同步码的方法和装置
CN101631098B (zh) * 2008-07-14 2012-12-05 电信科学技术研究院 一种同步信号获得及起始点确定方法和装置
CN101577576B (zh) * 2008-05-09 2013-01-23 杰脉通信技术(上海)有限公司 一种td-scdma终端初始下行同步方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000077961A1 (fr) * 1999-06-15 2000-12-21 Samsung Electronics Co., Ltd. Dispositif de synchronisation de frequence et de temporisation de symboles pour signaux ofdm et procede associe
US20030031238A1 (en) * 2000-03-27 2003-02-13 China Academy Of Telecommunications Technology Method for cell initial search in a CDMA mobile communication system
EP1416650A1 (fr) * 2002-11-02 2004-05-06 Lg Electronics Inc. Recherche de synchronisation initiale dans un système radio mobile

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000077961A1 (fr) * 1999-06-15 2000-12-21 Samsung Electronics Co., Ltd. Dispositif de synchronisation de frequence et de temporisation de symboles pour signaux ofdm et procede associe
US20030031238A1 (en) * 2000-03-27 2003-02-13 China Academy Of Telecommunications Technology Method for cell initial search in a CDMA mobile communication system
EP1416650A1 (fr) * 2002-11-02 2004-05-06 Lg Electronics Inc. Recherche de synchronisation initiale dans un système radio mobile

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008022591A1 (fr) * 2006-08-18 2008-02-28 Huawei Technologies Co., Ltd. Procédé de commande de l'identification des cellules dans un système lte et appareil à cet effet
CN101453237B (zh) * 2007-12-05 2012-09-05 大唐移动通信设备有限公司 搜索下行同步码的方法和装置
CN101577576B (zh) * 2008-05-09 2013-01-23 杰脉通信技术(上海)有限公司 一种td-scdma终端初始下行同步方法
CN101631098B (zh) * 2008-07-14 2012-12-05 电信科学技术研究院 一种同步信号获得及起始点确定方法和装置
CN102281082A (zh) * 2010-06-13 2011-12-14 中兴通讯股份有限公司 Td-scdma中单倍采样数据的下行同步码确认方法和装置

Similar Documents

Publication Publication Date Title
US8005129B2 (en) Acquisition circuit for low chip rate option for mobile telecommunication system
EP1337069B1 (fr) Synchronisation dans un système multiporteuse à étalement de spectre
KR100369791B1 (ko) 비동기 방식의 부호분할다중접속 통신시스템의 동기장치및 방법
KR100762602B1 (ko) 부호분할다중접속 이동통신시스템에서 기준 타이밍생성장치 및 방법
AU2002347866A1 (en) Acquisition circuit for low chip rate option for mobile telecommunication system
US7023831B2 (en) CDMA mobile communications apparatus and base station detecting method used therefor
US7065064B2 (en) Cell search using peak quality factors
EP1215827B1 (fr) Méthode de recherche de cellule par soustraction de motifs d'autocorrelation d'une valeur de correlation profile
US8879679B2 (en) Frequency offset compensation improvement for a long term evolution (LTE) searcher
US8761081B2 (en) Method and apparatus for cell searching in asynchronous CDMA systems
EP1134916A2 (fr) Méthode d'acquisition d'une synchronisation d'intervalle temporel dans un récepteur de communication à spectre étalé à séquence directe
US7486656B2 (en) Method and system for a mobile unit to synchronize with base station
WO2006067657A1 (fr) Procede et appareil de recherche de cellule dans un systeme de communication sans fil
KR20060058340A (ko) 비동기 방식 광대역 부호분할다중접속 시스템에서의코드그룹 획득 장치 및 방법
EP1391999B1 (fr) Procédé et appareil de recherche de cellule et de synchronisation pour un systeme WCDMA
EP1424790B1 (fr) Synchronisation de stations de base dans un système de communication cellulaire
KR100605977B1 (ko) 부호분할다중접속 통신시스템의 이동국의 셀 탐색장치 및 방법
EP2009817A2 (fr) Système de communication sans fil, station de base, et procédé de communication sans fil
EP1133078A1 (fr) Méthodes de synchronisation entre des stations de base et un équipement mobile dans un système de communication cellulaire

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BW BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KM KN KP KR KZ LC LK LR LS LT LU LV LY MA MD MG MK MN MW MX MZ NA NG NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SM SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): BW GH GM KE LS MW MZ NA SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LT LU LV MC NL PL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 2732/CHENP/2007

Country of ref document: IN

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 05823693

Country of ref document: EP

Kind code of ref document: A1

WWW Wipo information: withdrawn in national office

Ref document number: 5823693

Country of ref document: EP

点击 这是indexloc提供的php浏览器服务，不要输入任何密码和下载