WO2000064113A1 - Method for channel estimation in a tdma mobile radio telephone system - Google Patents

Method for channel estimation in a tdma mobile radio telephone system Download PDF

Info

Publication number
WO2000064113A1
WO2000064113A1 PCT/DE2000/001178 DE0001178W WO0064113A1 WO 2000064113 A1 WO2000064113 A1 WO 2000064113A1 DE 0001178 W DE0001178 W DE 0001178W WO 0064113 A1 WO0064113 A1 WO 0064113A1
Authority
WO
WIPO (PCT)
Prior art keywords
bursts
channel estimation
channel
mobile radio
participants
Prior art date
Application number
PCT/DE2000/001178
Other languages
German (de)
French (fr)
Inventor
Stefan Bahrenburg
Paul Walter Baier
Dieter Emmer
Jürgen Mayer
Johannes Schlee
Tobias Weber
Original Assignee
Siemens Aktiengesellschaft
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
Priority to DE1999117334 priority Critical patent/DE19917334A1/en
Priority to DE19917334.6 priority
Application filed by Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Publication of WO2000064113A1 publication Critical patent/WO2000064113A1/en

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00Baseband systems
    • H04L25/02Details ; Arrangements for supplying electrical power along data transmission lines
    • H04L25/0202Channel estimation

Abstract

The invention relates to a method for channel estimation in TDMA mobile radio telephone systems. The receiving values of several bursts can be used for channel estimation and are used for estimating a single channel impulse response when the period (Tauf) during which the successive data bursts are transmitted is significantly smaller than the coherence time (TK).

Description


  
 



  Description Method for Channel Estimation in a TDMA Mobile Radio System In TDMA-based CDMA mobile radio systems (TDMA = Time Division Multiple Access, CDMA = Code Division Multiple Access) a channel estimate is required to carry out the data estimation. The channel estimation in the TDMA-based systems is based on a training sequence, which is generally referred to as the midamble, the midamble being arranged between two data blocks. The unit consisting of the midamble and the two data blocks is called a burst.

   From Bernd Steiner it follows: "A contribution to the mobile radio channel estimation with special consideration of synchronous CDMA mobile radio systems with joint detection", progress reports VDI, row 10, no. 337, Düsseldorf: VDI-Verlag 1995 that the long lm of the midamble in TD CDMA mobile radio systems, due to the algorithm used for channel estimation, directly from the number of active subscribers K and the maximum expected length W of the channel impulse response from the approximation
Lm = W (K +1) is determined. The length Lm of the midamble is therefore a limiting factor for the number of active participants that can be present in the uplink per burst.

   If techniques such as "voice activity" or adaptive data rates are to be used, it may even be necessary to support more participants than are actually active per burst, in other words, to include them in the channel estimation.



  If intelligent antennas are also used in the base station, i.e. antennas that act selectively in the direction of the mobile radio subscriber, for example, subscriber-specific midambles are also required in the downlink, so that the midamble length also becomes a limiting factor here.



  Furthermore, it may be desirable in TD-CDMA mobile radio systems with a frequency reuse factor of r = 1 to include intercell interference signals from neighboring cells in the data selection. To do this, it is necessary to estimate channels to the neighboring stations or the mobile stations of the neighboring cells.



  However, this is only possible if sufficiently long middle ambles are available. As a result, there is the unsatisfactory situation that the more channels that have to be estimated, the smaller the remaining portion of the burst available for the data transmission. Therefore, on the one hand, many channels should be estimated, but on the other hand, only as small a portion of the burst as possible should be sacrificed for the midamble. In principle, this problem does not only exist with the above-mentioned channel estimation method of the publication mentioned above, but also with all estimation methods.

   In order to be able to achieve a sufficiently precise estimation result, a minimum number of measured values from the received midamble is required.



  So far, this conflict has not been resolved satisfactorily. Rather, a compromise has so far been found between the midamble length and the burst portion available for data transmission. The mid-bamboo length is usually dimensioned such that at least as many channels can be estimated as CDMA codes can be detected simultaneously in one cell. The number of CDMA codes that can be detected simultaneously is essentially determined by the spreading factor used and the intercell interference.

   Therefore, a useful compromise between mid-range length and the number of channels that can be estimated is only possible if the spreading factor is not too large, in other words if relatively few participants share the data transmission capacity of a burst. This means that the minimum data rate is too high for many applications and offers little scope for applying the above-mentioned capacity-increasing measures such as voice activity, adaptive data rates, antenna diversity and elimination of intercell interference.



  The object of the invention is therefore to create a method and a device with which an estimation of an increased number of channels is possible without increasing the proportion of the burst for the midamble.



  The object is achieved by the features of independent claims 1 and 10. Preferred embodiments of the invention are the subject of the dependent claims.



  The maximum time interval between two channel impulse responses within which the channel impulse responses can be regarded as correlated is defined as the coherence time TK.



  Furthermore, the coherence time TK is inversely proportional to the speed of a participant.



  If the channel impulse responses of successive bursts are now almost the same, i.e. the time period Tauf in which the successive data bursts are transmitted is significantly smaller than the coherence time TK defined above, the reception values of several bursts that can be used for the channel estimation are used to estimate a single channel impulse response. Participants with low speed in particular meet the condition Tauf TK.



  Short midambles (also called training sequences) can preferably be transmitted within the burst, the channel estimate then determining a current channel impulse response from the received values e (x) of several successive bursts x originating from the midambles. The received values of so many bursts must be taken into account in the channel estimation that the quality required for the channel estimation is achieved. This procedure is possible only if the channel impulse responses within the period in which the required receive values e (x), x = 1 ...



  X are received, are largely identical, in other words the condition Tauf TK is fulfilled. Furthermore, the lower the speed of a mobile station, the shorter the midamble, since this increases the coherence time TK and the higher the data rate can be achieved.



  The principle of piece-by-piece transmission of the midamble can consequently increase the number of participants. However, if you leave the length of the midamble within the bursts and interpret them as sections of a long midamble, it is possible to accommodate significantly more participants.



  Therefore, the problem of the number of subscribers normally limited by the channel estimation in TD-CDMA mobile radio systems can be regarded as solved.



  Furthermore, given the validity of the Tauf TK estimate, it is not absolutely necessary to use midambles within a burst, but the use of preambles is generally possible. Because of their property that they are not disturbed by the interference of previous symbols, preambles can advantageously be chosen to be shorter than midambles, which, for example, increases the data rate. If the preamble and the midamble are of equal length, the use of preambles enables a higher number of participants.



  Preferred embodiments of the invention are described below with reference to the drawings.



  Fig. +1 shows the division of a midamble into several shorter midambles, and Fig. 2 shows the use of periodic midamble codes.



  1 shows the division of a midamble m into a plurality of midamble m (x), where x runs from 1 to X. By sending the midamble m in sections in successive bursts, the midamble of a burst is shortened, so that the number of channels that can be estimated is increased due to the short midambles.



  In the case described here by way of example, the midamble m consists of X = 5 blocks of length W. The received signal originating only from the not yet divided midamble m is calculated for any subscriber k
EMI5.1
 The total received signal originating from the middle tones of the participants results from the superimposition of the signals of the K participants
EMI5.2
 Furthermore, the reception sequence em is shorter by W elements than the midamble, since reception values with interference from the data blocks cannot be used for channel estimation.



  So that the same algorithm can be used for channel estimation after splitting the midamble over several bursts as previously, which is based on the reception sequence Sm of the long KW, the signal em must also be generated by the transmission of the midamble in sections. In the example in FIG. 1, the signal 2 is composed of four sub-signals Sm = [em (l) ... em (4)] when the midamble m is distributed over X = 4 bursts.

   The received values of em (1) result from the transmission sequence of the midamble part m (1) and, since the channel impulse response has the length W, from the W-1 previous samples from block m (0). The received values of em (2) result from the transmission sequence m (2) and, since the channel impulse response has the length W, from the W-1 previous samples from block m (1). The same applies to the received values em (3) and e = (4).



  After the transmission of the four bursts, as shown in FIG. 1, the identical signal em = [em (1) ... em (4)] can be composed of the four reception sequences if the channel impulse response is constant. The channel estimation can be done inexpensively according to a method described in the article mentioned above.



  The estimation of the channel impulse response can be carried out in the steady state after the reception of each burst and thus of each section em (x) if, for example, an older em (1) is replaced by a just received section of the same name. The result of the channel estimation is therefore adaptively tracked to the slowly changing channel.



  Fig. 2 shows how blocks of the midamble emerge from a periodic midamble basic code described in the above-mentioned publication. If the supported number of subscribers K is a multiple of the number X of bursts to which the midamble is divided, the midamble distribution on the channel estimator manifests itself as a cyclical interchanging of the midambles used by the subscribers. Exactly the same channel estimator can be used for each burst, which uses the midamble reception signals of the last X bursts.

   The estimated value h of the channel impulse responses is obtained with the constant, right-circulating matrix G-1, which depends only on the midamble codes used, for h = G 1 em (3) Since only a part of the reception sequence em is newly acquired per burst, it is not absolutely necessary to perform a full channel estimate on each burst. Since it is a linear estimation algorithm, one can instead determine the difference between the old and new reception sequence Sm directly from the difference between the old and new reception sequence and update the estimation result h.



  In the example in FIG. 2, X = K = 4. The periodic basic code PGC is divided into four components, each beginning with ml, mW + lt m2W + lt and m3W + l. The periodic basic code PGC ends with the character mKW. The basic code PGC is always periodically shifted by one block between the participants T1, T2, T3 and T4, the participants ml sending the components ml and mW + l in the midamble M1, while the participants T2 send the components mW + and m2W + l

      The subscriber T3 sends the components m2W + l and m3W + l and the subscriber T4 the components m2W + l and ml in this order. Correspondingly, the 8 components of the periodic basic code PGC which are arranged above it in FIG. 2 are sent in the middle messages M2 to M4. The midamble M1 is sent in the first burst B1, while the midambles M2 to M4 are sent in the corresponding subsequent second to fourth bursts. 2, the components of the first midamble M1 sent in the first burst B1 are shown in the partial image at the bottom right.



  The invention can be applied to any mobile radio system with a TDMA component, and is therefore not restricted to use in TD-CDMA systems.

Claims

Claims 1. Method for channel estimation in a TDMA Mobile radio system, in which bursts transmitted between stations of the mobile radio system have training sequences for performing the channel estimation, and in the one necessary for channel estimation Training sequence m is divided into several partial training sequences m (x) with x = 1, ..., X, each part Training sequence m (x) in a burst of a sequence of X Bursts are sent so that the total Training sequence m is composed of the partial training sequences m (x) of the successive bursts.
2. The method of claim 1, wherein a period Tauf in which the successive bursts are transmitted is significantly smaller than the coherence time TK.
3. The method of claim 2, wherein the condition Tauf TK applies to participants at low speed.
4. The method according to any one of the preceding claims, -in which the reception values Sm (x), x = 1, ..., X of several bursts which can be used for the channel estimation are used to estimate a single channel impulse response h, and -in which the partial reception values em (x), x = l, ..., X des Received signal em so many bursts are taken into account in the channel estimation that the required quality for Channel estimate is reached.
5. The method according to any one of the preceding claims, in which the estimation of the channel impulse response h in the steady state is carried out after the start of each burst and each section em (x).
6. The method according to any one of the preceding claims, in which midambles or preambles are used as training sequences.
7. The method according to any one of the preceding claims, in which the channel is adapted adaptively by replacing a temporally older section em (x) of the received signal Sm of a burst by the section just received.
8. The method according to any one of the preceding claims, in which a periodic basic code is used to generate the training sequences of the participants.
9. The method according to claim 8, wherein the training sequence distribution at the channel estimator manifests itself as a cyclical interchanging of the training sequences used by the participants if the supported number of participants K is a multiple of the proportions X of the bursts over which the training sequence is divided.
10. TD-CDMA mobile radio system for using the method according to one of the preceding claims.
PCT/DE2000/001178 1999-04-16 2000-04-14 Method for channel estimation in a tdma mobile radio telephone system WO2000064113A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE1999117334 DE19917334A1 (en) 1999-04-16 1999-04-16 Channel estimation method for TD-CDMA mobile radio system
DE19917334.6 1999-04-16

Publications (1)

Publication Number Publication Date
WO2000064113A1 true WO2000064113A1 (en) 2000-10-26

Family

ID=7904861

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DE2000/001178 WO2000064113A1 (en) 1999-04-16 2000-04-14 Method for channel estimation in a tdma mobile radio telephone system

Country Status (2)

Country Link
DE (1) DE19917334A1 (en)
WO (1) WO2000064113A1 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004059864A1 (en) * 2002-12-30 2004-07-15 Koninklijke Philips Electronics N.V. Method and device to maintain synchronization tracking in tdd wireless communication
US6961365B2 (en) 2000-04-11 2005-11-01 China Academy Of Telecommunications Technology Method for signal processing in user equipment of CDMA mobile communication system
WO2006102792A1 (en) * 2005-03-29 2006-10-05 Zte Corporation A method of channel estimate in tdd-cdma system
CN1305324C (en) * 2003-03-21 2007-03-14 乐金电子(中国)研究开发中心有限公司 Adaptive channel evaluating method and device based on expected medium code of construction

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7068631B2 (en) 2001-08-06 2006-06-27 Telefonaktiebolaget Lm Ericsson (Publ) Training sequence hopping in a radio communication system
EP2226963B1 (en) * 2009-03-04 2013-05-08 Sony Corporation Receiving apparatus and method with non-oversampling analog to digital conversion

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4212300A1 (en) * 1992-04-11 1993-10-14 Paul Walter Prof Dr Ing Baier Simultaneous channel evaluation for digital communications network - using correlator to evaluate channel responses to time shifted test signals obtained from equal periodic base signal
DE4311656C1 (en) * 1993-04-08 1994-04-21 Ant Nachrichtentech Adapting channel response for mobile communications receiver - using least mean square algorithm for correcting estimated channel response for each sector of received signal burst
DE19733336A1 (en) * 1997-08-01 1999-02-18 Siemens Ag Method and radio station for data transmission

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4233222C2 (en) * 1992-10-02 1995-07-20 Siemens Ag Measuring system (channel sounder) for the investigation of mobile radio channels
DE19747369A1 (en) * 1997-10-27 1999-05-06 Siemens Ag Transmission channel estimation in telecommunication systems with wireless telecommunication

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4212300A1 (en) * 1992-04-11 1993-10-14 Paul Walter Prof Dr Ing Baier Simultaneous channel evaluation for digital communications network - using correlator to evaluate channel responses to time shifted test signals obtained from equal periodic base signal
DE4311656C1 (en) * 1993-04-08 1994-04-21 Ant Nachrichtentech Adapting channel response for mobile communications receiver - using least mean square algorithm for correcting estimated channel response for each sector of received signal burst
DE19733336A1 (en) * 1997-08-01 1999-02-18 Siemens Ag Method and radio station for data transmission

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
STEINER B ET AL: "OPTIMUM AND SUBOPTIMUM CHANNEL ESTIMATION FOR THE UPLINK OF CDMA MOBILE RADIO SYSTEMS WITH JOINT DETECTION", EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS AND RELATED TECHNOLOGIES, vol. 5, no. 1, 1994, IT,AEI, MILANO, pages 39 - 50, XP000445714, ISSN: 1120-3862 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6961365B2 (en) 2000-04-11 2005-11-01 China Academy Of Telecommunications Technology Method for signal processing in user equipment of CDMA mobile communication system
WO2004059864A1 (en) * 2002-12-30 2004-07-15 Koninklijke Philips Electronics N.V. Method and device to maintain synchronization tracking in tdd wireless communication
CN100438640C (en) * 2002-12-30 2008-11-26 Nxp股份有限公司 Sampling method and its device for down synchronous tracking in TDD radio communication
US7715510B2 (en) 2002-12-30 2010-05-11 St-Ericsson Sa Method and device to maintain synchronization tracking in TDD wireless communication
CN1305324C (en) * 2003-03-21 2007-03-14 乐金电子(中国)研究开发中心有限公司 Adaptive channel evaluating method and device based on expected medium code of construction
WO2006102792A1 (en) * 2005-03-29 2006-10-05 Zte Corporation A method of channel estimate in tdd-cdma system

Also Published As

Publication number Publication date
DE19917334A1 (en) 2000-10-26

Similar Documents

Publication Publication Date Title
EP0210700B1 (en) Digital radio transmission system with central, communication-associated organization channel in the time multiplex frame
EP0893013B1 (en) Spread spectrum random access systems and methods for time division multiple access radiotelephone communications systems
CA2264746C (en) Radio communications systems and methods for jittered beacon transmission
RU2395919C2 (en) Transfer of control signals for system of wireless communication with orthogonal frequency division
JP3192428B2 (en) Method and mobile station for performing handover in a CDMA cellular radio system
ES2247583T3 (en) Apparatus and procedure to reduce the collision of messages between mobile stations that access simultaneously to a base station of a cdma cellular communications system.
US5570349A (en) Wireless direct sequence spread spectrum digital cellular telephone system
EP0717913B1 (en) Data transmission method, base station, and subscriber terminal
DE69938529T2 (en) Receive time-switched transmit diversity (TSTD) signals and non-TSTD signals
EP1601119B1 (en) Radio base station apparatus and radio communication method
KR100838976B1 (en) Method and system for forward link beam forming in wireless communications
US6275506B1 (en) Radio transmission method for digital multimedia data signals between subscriber stations in a local network
JP3792512B2 (en) Random access in mobile telecommunications systems
CA2382377C (en) Apparatus and method for reporting service load to mobile station in mobile telecommunication system
US5568472A (en) Code division multiple access mobile communication system
EP0668668B1 (en) Mobile CDMA/TDD telecommunication system with transmission antennas selection means
CA2611654C (en) Transmitter, receiver, mobile communication system and synchronization channel
RU2122290C1 (en) Method and base station for time matching of received signals in communication system with multiple-station access and code channel separation, user set
EP1110360B1 (en) Method and apparatus for reducing amplitude variations in communication signals employing inserted pilot symbols
RU2315430C2 (en) Multi access code division transmission system
RU2369031C2 (en) Wireless communication system with configurable length of cyclic prefix
EP1941634B1 (en) Pilot symbol transmission in wireless communication systems
US7110781B1 (en) Mobile telecommunications systems
JP3144778B2 (en) Access to communication systems
EP1338114B1 (en) Training sequence for a radio communications system

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): CN JP US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase in:

Ref country code: JP