EP1825611A1 - Procede d'estimation de canal base sur la diversite de pilotes - Google Patents

Procede d'estimation de canal base sur la diversite de pilotes

Info

Publication number
EP1825611A1
EP1825611A1 EP05821857A EP05821857A EP1825611A1 EP 1825611 A1 EP1825611 A1 EP 1825611A1 EP 05821857 A EP05821857 A EP 05821857A EP 05821857 A EP05821857 A EP 05821857A EP 1825611 A1 EP1825611 A1 EP 1825611A1
Authority
EP
European Patent Office
Prior art keywords
channel
pilot symbols
ccpch
cpich
channel estimation
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP05821857A
Other languages
German (de)
English (en)
Other versions
EP1825611A4 (fr
Inventor
Byoung-Gi Kim
Kun-Seok Kang
Do-Seob Ahn
Ho-Jin Lee
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Electronics and Telecommunications Research Institute ETRI
Original Assignee
Electronics and Telecommunications Research Institute ETRI
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 Electronics and Telecommunications Research Institute ETRI filed Critical Electronics and Telecommunications Research Institute ETRI
Publication of EP1825611A1 publication Critical patent/EP1825611A1/fr
Publication of EP1825611A4 publication Critical patent/EP1825611A4/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0204—Channel estimation of multiple channels
    • 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
    • H04B1/7097—Interference-related aspects
    • H04B1/711—Interference-related aspects the interference being multi-path interference
    • H04B1/7115—Constructive combining of multi-path signals, i.e. RAKE receivers
    • H04B1/712—Weighting of fingers for combining, e.g. amplitude control or phase rotation using an inner loop
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0224—Channel estimation using sounding signals
    • H04L25/0228—Channel estimation using sounding signals with direct estimation from sounding signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/024—Channel estimation channel estimation algorithms
    • 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 method for estimating a channel in a communication system; and, more particularly, to a method for estimating a channel using an improved pilot diversity.
  • a purpose of next generation satellite or mobile communication system is to provide various communication services to whomever, wherever and whenever.
  • S-UMTS European satellite-universal mobile telecommunications systems
  • ETSI European Telecommunications Standards Institute
  • a coherent demodulation method is used in uplink and downlink to improve a link capacity.
  • a channel estimate is performed by using a pilot signal which is not modulated for the coherent demodulation.
  • Channel estimation using a pilot symbol structure is adopted by W-CDMA standard.
  • the channel estimation using the pilot symbol structure periodically performs the time-division multiplexing for pilot symbols, which are known to a transmitter and a receiver, and data symbols and transmits the multiplexed symbols.
  • a channel change in a data symbol period is compensated with a channel estimation value in a pilot symbol period.
  • the above channel estimation method is a method for estimating a channel using only pilot symbols of a dedicated physical control channel (DPCCH).
  • DPCCH dedicated physical control channel
  • Another method compensates data symbols for channel change by transferring pilot symbols, which is known to a transmitter and a receiver, using predetermined pilot symbol patterns.
  • the above method estimates a channel using only a common pilot channel (CPICH).
  • CPICH common pilot channel
  • a demerit of the conventional channel estimation method is to incur more errors when a channel related with the channel estimation is under deep fading.
  • S-CCPCH secondary common control physical chann el
  • a method for estimating a channel using pilot diversity including the steps of extracting pilot symbols of a secondary common control physical channel (S-CCPCH) which is despreaded, calculating a mean value of the pilot symbols of the S-CCPCH, calculating a power ratios of the pilot symbols of the S-CCPCH, those of a dedicated physical control channel (DPCCH), and those of a common pilot channel (CPICH), and assigning weights to the pilot symbols of the S-CCPCH, those of the DPCH, and those of the CPICH.
  • S-CCPCH secondary common control physical channel
  • DPCCH dedicated physical control channel
  • CPICH common pilot channel
  • a channel estimation method in the present invention provides a more improved performance than channel estimation in a receiver of a terminal having conventional pilot symbols of a CPICH or a DPCCH by combining pilot symbols of a CPICH, a DPCCH and a secondary common control physical channel (S-CCPCH), and estimating a channel.
  • S-CCPCH secondary common control physical channel
  • FIG. 1 is a diagram showing a structure of a rake receiver to adopt a channel estimation method in accordance with an embodiment of the present invention
  • Fig. 2 is a diagram showing a frame structure of a DPCH used in an embodiment of the present invention
  • Fig. 3 is a diagram showing a frame structure of a CPICH used in an embodiment of the present invention
  • Fig. 4 is a diagram showing a frame structure of a S-CCPCH used in an embodiment of the present invention
  • Fig. 5 is a diagram showing one finger out of fingers of the rake receiver described in Fig. 1
  • Fig. 6 is a flow chart showing channel estimation process in accordance with an embodiment of the present invention.
  • Fig. 6 is a flow chart showing channel estimation process in accordance with an embodiment of the present invention
  • Fig. 7 is a diagram showing a process combining pilot symbols of a S-CCPCH, those of a DPCH and those of a CPICH when performing the channel estimation in accordance with the flow chart illustrated in Fig. 6; and [24]
  • Fig. 8 is a diagram showing a relative timing correlation of a channel estimation method that combines a CPICH, a DPCH and a S-CCPCH to estimate a channel in accordance with an embodiment of the present invention.
  • Fig. 1 is a diagram showing a structure of a rake receiver to adopt channel estimation method in accordance with an embodiment of the present invention.
  • the rake receiver includes a correlator 110 and an estimation unit 120 in each finger. A signal received through a multipath channel is divided by fingers of the rake receiver, and an ideal maximum ratio combining (MRC) method is performed for the divided signal through channel estimation.
  • MRC ideal maximum ratio combining
  • the rake receiver includes M fingers and a received signal R(t) is multiplied by a scrambling code and then descrambled in each finger.
  • the de- scrambled signal is despreaded by a channelization code and channel-estimated in the estimation unit 120.
  • An output value of each finger is combined by a combiner and then outputted to a deinterleaver.
  • the present invention uses the pilot symbols of a DPCH, those of a CPICH, and those of an S-CCPCH for the channel estimation.
  • Fig. 2 shows a diagram of a frame structure of the DPCH used in the present invention.
  • the channel estimation is performed by using the pilot symbols that a control channel of the DPCCH and a data channel of the DPDCH are multiplexed in time-division and are transferred, and data symbols of the DPDCH is compensated based on the channel estimated result.
  • a frame has 15 slots; each slot has 2560 chips; a chip rate is 3.84Mcps; the DPCH is a power control based channel.
  • FIG. 3 provides a diagram of a frame structure of the CPICH used in an embodiment of the present invention.
  • a transmitter transmits the pilot symbols to a receiver according to a predetermined pattern for the channel estimation; the receiver, which has already known the predetermined pattern, estimates the channel by using the pilot symbols; and the CPICH is a non-power control based channel.
  • Fig. 4 represents a diagram of a frame structure of the S-CCPCH used in an embodiment of the present invention.
  • the present invention uses pilot symbols of the S-CCPCH for the channel estimation in the S-CCPCH shown in Fig. 4.
  • the S-CCPCH is adopted in the present invention since a data rate of the S-CCPCH is similar to that of the DPCH.
  • Fig. 5 illustrates a diagram of one finger of fingers in the rake receiver shown in
  • a signal received in a rake receiver is despreaded by a despreader 210, and then divided into a data signal and a pilot signal by the pilot symbols dividing unit not shown in drawings.
  • the data signal and the pilot signal are inputted to a delay unit 221 and a channel estimation unit 223, respectively.
  • the pilot signal inputted to the channel estimation unit 223 is pilot symbols of a DPCH, an S-CCPCH, and a CPICH.
  • the channel estimation unit 223 outputs a channel estimation value as described below.
  • the channel estimation value is multiplied by a delayed data signal made by delaying the data signal as long as a predetermined time in the delay unit 221, and the multiplied value is outputted to a combiner.
  • the delay unit 221 and a multiplier play a role of compensating the data signal.
  • an output of the combiner is transmitted through a deinterleaver 230, a rate matching encoder 240, and a FEC decoder 250.
  • the received data which was encoded in a transmitting terminal is decoded to original data and then outputted through the decoder 250.
  • Fig. 6 is a flow chart showing a channel estimation process in accordance with the present invention.
  • pilot symbols extracting unit extracts pilot symbols of a despreaded S-CCPCH in step S610.
  • the channel estimation unit 223 calculates a mean value of the pilot symbols of the S-CCPCH in step S620, wherein a method for calculating the mean value of the pilot symbols of the S-CCPCH follows a method for calculating a mean value of pilot symbols of the DPCH since a data rate of the S- CCPCH is the same as that the DPCH.
  • step S630 a power ratio of the pilot symbols of each channel is calculated in step S630, wherein the electrical power ratio of each channel is obtained by calculating electrical power ratios of the pilot symbols of the S-CCPCH and the DPCH to the pilot symbols of the CPICH.
  • step S640 each pilot symbols of the S-CCPCH, the DPCH and the CPICH is multiplied by a weight, wherein the weight is a value assigned with 0 to 1 according to a level of the received signal. Then, a channel estimation value is outputted by combining the pilot symbols of the S-CCPCH, those of the DPCH, and those of the CPICH with allotment of the weights in step S650.
  • the pilot symbols of the S-CCPCH can be used as a frame synchronization word as well as used in the channel estimation, the pilot symbols of the S- CCPCH are not used in the channel estimation in case that the pilot symbol of the S- CCPCH is transferred to a transport channel of a forward access channel (FACH) or a paging channel (PCH) in the beginning stage and is used in the other channel estimation.
  • FACH forward access channel
  • PCH paging channel
  • Fig. 7 is a diagram showing a process combining the pilot symbols of the S-
  • CCPCH are multiplied by the weights ⁇ , ⁇ and ⁇ and then combined, to thereby output a final channel estimation value c(n, k, 1).
  • Fig. 8 shows a relative timing correlation of the channel estimation method that combines the CPICH, the DPCH and the S-CCPCH for the channel estimation in accordance with the present invention.
  • the channel estimation in accordance with the present invention is compared with a channel estimation method based on only pilot symbols of the CPICH, and a channel estimation method combining pilot symbols of the DPICH and those of the CPICH.
  • the equation 1 represents a channel estimation using N symbols of the CPICH in one slot after a multipath fading and a dispreading process in a rake receiver.
  • ⁇ (i) means a channel gain to be estimated and n(i) means a noise including the interference of other cells. It is presumed that a mean value of n(i) is 0, and a variance of n(i) is ⁇ n in case that there is no loss.
  • a receiver of a terminal acknowledges a pilot pattern for pilot symbols of the
  • the equation 2 shows a method for estimating a channel by combining pilot symbols of the DPCH and pilot symbols of the CPICH.
  • m(j) is an additive white gaussian noise (AWGN) whose average value is 0 and variance is ⁇ m . Since it is presumed that the channel gain is not changed during one slot of an estimation period, ⁇ (i) and ⁇ (i) become ⁇ and ⁇ respectively.
  • the equation 3 is an equation extended from the equation 2. That is, the equation 3 shows a method for estimating a channel by combining pilot symbols of the DPCH, those of the CPICH, and those of the S-CCPCH.
  • K means the number of pilot symbols in one slot of the S-CCPCH used in estimating a channel gain
  • CCPCH are different from each other, n(i), m(j) and l(k) are independent of each other.
  • a channel estimation combining pilot symbols of the CPICH, those of the DPCH and those of the S-CCPCH is compared with a channel estimation using only pilot symbols of the CPICH, and a channel estimation combining pilot symbols of the CPICH and those of the DPCH.
  • a vector of a signal received in a rake receiver of a terminal is as follows.
  • T denotes an operator of a transpose matrix
  • ⁇ denotes a channel estimation value (case 1) using the CPICH
  • ⁇ denotes a channel estimation value (case 2) combining the DPCH and the CPICH
  • ⁇ denotes a channel estimation value (case 3) combining the CPICH, the DPCH and the S-CCPCH.
  • a cramer-rao lower bound (CRLB) is used to analyze performances of the above cases to thereby compare channel estimation values of the above cases.
  • a performance analysis is performed as follows by comparing the case 1 with the case 2, and comparing the case 2 with the case 3 through the use of a Fisher information matrix,
  • Equation 6 [85] [86]
  • Equation 7 is an inverse transformation of the equation 6, which is to calculate the variance when the pilot symbols of the CPICH and those of the DPCH are combined.
  • the channel estimation combining the CPICH, the DPCH and the S-CCPCH is superior to the channel estimation using only the CPICH and the channel estimation combining the CPICH and the DPCH.
  • CCPCH to the conventional methods can obtain an improved pilot diversity gain by performing the channel estimation using other channel in case that once channel is not come up to a required level of a received signal, it is possible to implement an ideal maximum ratio combining method in a rake receiver.
  • the method of the present invention can be embodied as a program and stored in recording media readable by a computer, e.g., CD-ROM, RAM, floppy disk, hard disk, magneto-optical disk, etc.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Power Engineering (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

Cette invention concerne un procédé d'estimation de canal basé sur la diversité de pilotes. Le procédé consiste à extraire des symboles pilotes d'un canal de commande physique secondaire commun (S-CCPCH) qui est désétalé, à calculer une valeur moyenne des symboles pilotes du S-CCPCH, à calculer un rapport de puissance des symboles pilotes du S-CCPCH, de ceux d un canal de commande physique spécialisé (DPCCH) et de ceux d'un canal de commande pilote commun (CPICH) et à attribuer des pondérations aux symboles pilotes du S-CCPCH, à ceux du DPCH et à ceux du CPICH.
EP05821857A 2004-12-13 2005-12-13 Procede d'estimation de canal base sur la diversite de pilotes Withdrawn EP1825611A4 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR1020040104747A KR100581083B1 (ko) 2004-12-13 2004-12-13 향상된 파일럿 다이버시티를 이용한 채널추정방법
PCT/KR2005/004262 WO2006065053A1 (fr) 2004-12-13 2005-12-13 Procede d'estimation de canal base sur la diversite de pilotes

Publications (2)

Publication Number Publication Date
EP1825611A1 true EP1825611A1 (fr) 2007-08-29
EP1825611A4 EP1825611A4 (fr) 2012-07-25

Family

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Family Applications (1)

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EP05821857A Withdrawn EP1825611A4 (fr) 2004-12-13 2005-12-13 Procede d'estimation de canal base sur la diversite de pilotes

Country Status (3)

Country Link
EP (1) EP1825611A4 (fr)
KR (1) KR100581083B1 (fr)
WO (1) WO2006065053A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8391253B2 (en) * 2008-11-20 2013-03-05 Telefonaktiebolaget L M Ericsson (Publ) Time-division multiplexed pilot signal for integrated mobile broadcasts
US9674002B2 (en) * 2012-10-09 2017-06-06 Telefonaktiebolaget Lm Ericsson (Publ) Channel estimation in a multi-antenna wireless communications system
CN103236995B (zh) * 2013-04-24 2017-04-12 华为技术有限公司 信道估计方法和用户设备

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002089358A1 (fr) * 2001-04-26 2002-11-07 Nokia Corporation Procede et equipement de transmission de donnees
EP1469686A1 (fr) * 2002-01-18 2004-10-20 Fujitsu Limited Procede et dispositif pour commander la retroaction dans la diversite de transmission en boucle fermee

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100689398B1 (ko) * 1999-10-09 2007-03-08 삼성전자주식회사 이동통신시스템에서 폐루프 송신 안테나 다이버시티 장치 및 방법
KR100330222B1 (ko) * 2000-05-16 2002-03-25 윤종용 이동통신시스템의 채널 복조 장치 및 방법
JP2003304177A (ja) * 2002-04-11 2003-10-24 Matsushita Electric Ind Co Ltd 無線受信方法及び通信端末装置

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002089358A1 (fr) * 2001-04-26 2002-11-07 Nokia Corporation Procede et equipement de transmission de donnees
EP1469686A1 (fr) * 2002-01-18 2004-10-20 Fujitsu Limited Procede et dispositif pour commander la retroaction dans la diversite de transmission en boucle fermee

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
ERICSSON: "CR 25.211-079: Clarification of downlink phase reference", 3GPP DRAFT; R1-00-1187_CR25211-079_DED_PILOT, 3RD GENERATION PARTNERSHIP PROJECT (3GPP), MOBILE COMPETENCE CENTRE ; 650, ROUTE DES LUCIOLES ; F-06921 SOPHIA-ANTIPOLIS CEDEX ; FRANCE, vol. RAN WG1, no. Pusan, Korea; 20001007, 7 October 2000 (2000-10-07), XP050093438, [retrieved on 2000-10-07] *
See also references of WO2006065053A1 *

Also Published As

Publication number Publication date
KR100581083B1 (ko) 2006-05-22
EP1825611A4 (fr) 2012-07-25
WO2006065053A1 (fr) 2006-06-22

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