WO2007076638A1 - Procede de demodulation 8psk dans un systeme edge - Google Patents

Procede de demodulation 8psk dans un systeme edge Download PDF

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Publication number
WO2007076638A1
WO2007076638A1 PCT/CN2005/002438 CN2005002438W WO2007076638A1 WO 2007076638 A1 WO2007076638 A1 WO 2007076638A1 CN 2005002438 W CN2005002438 W CN 2005002438W WO 2007076638 A1 WO2007076638 A1 WO 2007076638A1
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Prior art keywords
channel
signal
max
channel parameter
search
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PCT/CN2005/002438
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English (en)
Chinese (zh)
Inventor
Gang Xiong
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Zte Corporation
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Application filed by Zte Corporation filed Critical Zte Corporation
Priority to CN2005800518664A priority Critical patent/CN101292485B/zh
Priority to PCT/CN2005/002438 priority patent/WO2007076638A1/fr
Priority to BRPI0520826A priority patent/BRPI0520826B1/pt
Publication of WO2007076638A1 publication Critical patent/WO2007076638A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
    • H04L27/22—Demodulator circuits; Receiver circuits
    • H04L27/233—Demodulator circuits; Receiver circuits using non-coherent demodulation
    • H04L27/2338—Demodulator circuits; Receiver circuits using non-coherent demodulation using sampling
    • 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
    • H04L25/0212—Channel estimation of impulse response
    • H04L25/0216—Channel estimation of impulse response with estimation of channel length
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F11/00—Error detection; Error correction; Monitoring
    • G06F11/07—Responding to the occurrence of a fault, e.g. fault tolerance
    • G06F11/08—Error detection or correction by redundancy in data representation, e.g. by using checking codes
    • G06F11/10—Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's

Definitions

  • the invention belongs to an adaptive demodulation method in the field of mobile communication, and in particular relates to an adaptive 8PSK equalization demodulation method suitable for an EDGE system. Background technique
  • EDGE Enhanced Data Rates for GSM Evolution
  • 8PSK multi-level digital modulation-8PSK modulation as standard technical terminology, hereinafter referred to as EDGE and 8PSK. Since 8PSK modulation maps 3 consecutive bits to one symbol of I/Q coordinates, it can provide higher bit rate and spectral efficiency.
  • the EDGE system can provide 9 different modulation and coding modes, MCS (Modulation and Coding Scheme), in which different MCS1 ⁇ 4 still use the GMSK modulation mode in the GSM system, while the MCS5 9 uses the 8PSK. Modulation.
  • MCS Modulation and Coding Scheme
  • the channel characteristics of the wireless channel are very poor, mainly manifested by multipath fading and Doppler fading.
  • Multipath fading can cause inter-symbol interference in the signal, and the receiving end must use equalization techniques to eliminate the effects of the channel.
  • Several typical wireless channel propagation models are specified in the GSM EDGE protocol, such as the static model Static, the urban model TU50 (50 represents the mobile station's speed of 50km/h), the suburban model RA250, and so on.
  • the size of the modulation symbol table of the signal is M-8.
  • the reduced state sequence estimation algorithm RSSE Reduced-State Sequence Estimation, see A. Duel-Hallen, c. Heegard, "Delayed Decision-Feedback Sequence Estimation,” IEEE Trans. Comm. vol. 37, pp 428-436, May 1989
  • Delayed Decision-Feedback Sequence Estimation see MV Eyuboglu, SUH Qureshi, "Reduced-State Estimation with Set Partition and Decision Feedback," IEEE Trans. Comm. Vol. 36, pp. 13-20, Jan. 1988
  • RSSE Similar to DDFSE, RSSE also needs to use PSP to calculate branch metrics.
  • RSSE and DDFSE are relatively simple to implement, due to the uncertainty of airborne channel propagation, the dispersion length of the actual channel can vary between 2 and 6. If the number of fixed states and the length of the decision feedback are used, the actual channel dispersion length is small. In the case of the case, not only a certain loss in demodulation performance but also an increase in computational complexity is caused. Therefore, it is necessary to find an adaptive equalization demodulation method to obtain a higher demodulation gain with lower complexity.
  • US Patent No. 5,644,603 "Maximum Likelihood Sequence Estimator with Variable Number of States" uses a training sequence to estimate channel parameters, and determines the number of states of the Viterbi algorithm based on the estimated channel parameters to obtain an output of the equalization demodulation. result.
  • the modulation symbol table of the signal is relatively large, the complexity of the system increases exponentially and is not suitable for use in the EDGE system 8PSK equalization demodulation.
  • the patent only determines whether the energy of the previous order channel parameters is greater than a predetermined threshold to determine the actual channel dispersion length. This method is susceptible to signal delay, and the thresholds mentioned in this method are difficult to determine and are not easy to implement in practical systems.
  • the object of the present invention is to propose an adaptive 8PSK equalization demodulation method for the EDGE system, jointly estimating based on the estimated channel parameter values, and simultaneously determining the timing advance and channel of the signal by the two steps of coarse synchronization and fine synchronization.
  • the dispersion length adaptively adopts the reduced state method for 8PSK equalization demodulation.
  • a method for adaptive 8PSK demodulation for an EDGE system comprising the following steps -
  • a signal inversion module inverts the received I, Q signals of multiple sampling rates
  • a channel parameter estimation module performs sliding correlation on the inverted signal to obtain an estimated channel parameter value at a multiple sampling rate
  • C. Perform joint estimation according to the estimated value of the channel parameter, and determine the time advance of the signal and the actual dispersion length of the channel by the two steps of coarse synchronization and fine synchronization, wherein the coarse synchronization output time advance quantity rough estimation value and channel An estimate of the dispersion length, the fine estimate of the fine synchronization output time advance;
  • the inverted signal is synchronized and downsampled, and the estimated values of the channel parameters are synchronized and downsampled;
  • the whitened matched and filtered signal is sent to the adaptive equalization demodulator, and based on the actual dispersion length of the channel, the 8PSK equalization demodulation is adaptively adopted in a reduced state according to a predetermined criterion.
  • the method, wherein the coarse synchronization process comprises the following steps:
  • the initial search window size is 2N, and N is the number of sampling points in the symbol period;
  • N h is the search length
  • the current search window size is the window size, find the energy of the largest channel parameter estimation value and En—Max, and record the sampling point where it is located.
  • Position TA—Max simultaneously find the energy of the second largest channel parameter estimate and En—Sec—Max and the corresponding position TA—Sec—Max;
  • the method, wherein the fine synchronization process comprises the following steps -
  • the initial search window size is K d xN ;
  • C22 in the [(TA-Coarse-l)xN+l, TA-CoarsexN] sampling point search range, find the energy sum of the largest channel parameter estimation value, and simultaneously record the sampling point position where it is located;
  • the method wherein the initialized search start symbol position is a first symbol position of a channel parameter estimation value.
  • the input of the criterion is the actual dispersion length of the channel
  • the whitening matched filtered input parameter is a channel parameter estimation value after synchronization and downsampling.
  • the method for adaptive 8PSK demodulation applied to the EDGE system improves the performance of the baseband system when the actual channel dispersion length is relatively small, compared with the conventional method, while satisfying the EDGE protocol specification. At the same time, it also ensures that the performance of the baseband system remains unchanged when the channel dispersion length is relatively large.
  • FIG. 1 is a schematic diagram showing a basic channel model of a mobile communication system according to the method of the present invention
  • FIG. 2 is a schematic diagram of a data format of a multi-sampling rate I, Q signal received by the baseband of the method of the present invention
  • FIG. 3 is a diagram of the apparatus for adaptive 8PSK equalization demodulation of the method of the present invention
  • FIG. 4 is a flow chart showing the implementation of coarse synchronization in the joint estimation signal timing advance and channel dispersion length of the method of the present invention
  • 5 is a flow chart showing the implementation of fine synchronization in the joint estimation signal timing advance and channel dispersion length of the method of the present invention
  • 6a and 6b are schematic diagrams showing examples of coarse synchronization and fine synchronization implementation of the method of the present invention.
  • FIG. 7 is a schematic illustration of the 8PSK subset splitting of the method of the present invention. detailed description
  • the method of the invention proposes an adaptive 8PSK equalization demodulation method for the EDGE system, that is, the joint estimation is first based on the estimated channel parameter values, and the time advance and the channel of the signal are simultaneously determined by the two steps of coarse synchronization and fine synchronization.
  • the dispersion length and then based on the dispersion length, adaptively adopts a reduced state method for 8PSK equalization demodulation according to a predetermined criterion, and the method of the invention satisfies the EDGE protocol specification as compared with the conventional method. It can improve the performance of the baseband system when the actual channel dispersion length is relatively small, and also ensure that the performance of the baseband system does not change when the channel dispersion length is relatively large.
  • the basic schematic diagram of the channel model of the mobile communication system of the method of the present invention is shown in FIG. 1.
  • the baseband receiver receives data transmitted over the air wirelessly, and firstly, the demodulation module demodulates the received baseband I and Q signals. The demodulated result is deinterleaved and then sent to the channel decoding module for channel decoding.
  • the demodulation module is located at the front end of the receiver. It can be seen that the performance of the demodulation directly determines the performance of the entire mobile communication system.
  • the data format of the I, Q signal of the multiple sampling rate received by the baseband of the method of the present invention is as shown in FIG. 2.
  • N In the signal received by the receiving end, there are N in one symbol period. Sampling point. That is, 1 ⁇ 1> ⁇ , where T s is the sampling period.
  • the value of N is related to the actual system. Generally speaking, N can take 1, 2, 4 or 8.
  • FIG. 3 is a structural diagram of an adaptive 8PSK equalization demodulation implementation according to the method of the present invention, and the structure thereof includes: a signal inversion module, a channel parameter estimation module, a signal delay advance determination module, and a channel dispersion length determination module. , signal synchronization and downsampling module, channel parameter estimation value synchronization and downsampling module, whitening matched filtering module and adaptive equalization demodulation module.
  • the method for adaptive 8PSK equalization demodulation of the EDGE system of the present invention comprises the following steps: 1. inverting the received I, Q signals of multiple sampling rates;
  • the two steps are divided into coarse synchronization and fine synchronization.
  • the coarse synchronization outputs a rough estimate of the time advance and the estimated value of the channel dispersion length, while the fine synchronization outputs a fine estimate of the time advance.
  • the rough synchronization process provided by the method of the invention comprises the following steps:
  • the predetermined criterion may be adaptively used to perform 8PSK equalization demodulation by using the reduced state method.
  • the range of values is 2 ⁇ ⁇ 6, and the range of values is 2 ⁇ / ⁇ .
  • This guideline is:
  • the signal model can be expressed as -
  • ⁇ is the received signal. It is the symbol point position, i is the sampling point position, and l ⁇ i ⁇ W. c (for the transmitted signal, the synthesized channel parameter, ",. (for noise.
  • Ot is the signal after the flip.
  • the channel parameter estimation module is configured to correlate the input training sequence with the inverted signal to obtain an estimated value of the channel parameter, and output the estimated value of the obtained channel parameter to the determining module of the signal delay advance amount, and the channel dispersion length. Determining the module and the channel parameter estimation value synchronization and downsampling module, the calculation formula is -
  • the range is [0, N A - 1]
  • N A is the search length, and in practice, a value of about 3L can be taken.
  • A is the length required to estimate the channel parameters, typically less than the length of the training sequence.
  • the present invention employs two steps of coarse synchronization and fine synchronization to jointly estimate the delay advance of the signal and the dispersion length of the channel.
  • the determination module of the signal delay advancement and the input of the determination module of the channel dispersion length are the estimated values of the channel parameters, and the outputs are the timing advance of the signal Timing-Advance and the dispersion length of the channel, respectively.
  • the time advance of the signal is output to the signal synchronization and downsampling module and the channel parameter estimation value synchronization and downsampling module, and the dispersion length of the channel is output to the whitening matched filter. Module.
  • the estimated signal timing advance can be expressed as:
  • Timing-Advance k TA xN + t
  • ⁇ is the index of the time advance sign
  • r is the index of the time advance sample point
  • the signal synchronization and downsampling module synchronizes and downsamples the inverted signal based on the timing advance of the signal.
  • the channel parameter estimate synchronization and downsampling module synchronizes and downsamples the estimated values of the signal parameters based on the timing advance of the signal.
  • the synchronized and downsampled channel parameter estimates are output to a whitening matched filtering module. Its calculation formula is:
  • the input of the whitening matched filter module is the synchronized and downsampled signal and channel parameter estimates, while the output is whitened to match the filtered signal and channel parameters.
  • the final bit value obtained.
  • the input of the predetermined criterion is the actual dispersion length of the channel, and the output is the order of the channel / and the number of states on each order N ⁇ ⁇ N ⁇ Np; ..., NM ⁇ .
  • the value range is 2 ⁇ ⁇ ⁇ 6, and the value range is 2 ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ .
  • the criterion is:
  • FIG. 4 is a flow chart showing the implementation of the coarse synchronization of the joint estimation signal timing advance and the channel dispersion length of the method of the present invention, and the specific implementation steps are -
  • FIG. 5 is a flow chart showing the implementation of fine synchronization in joint estimation signal timing advance and channel dispersion length in the method of the present invention, and fine synchronization is mainly to find all the sample points at two symbol positions of TA-Coarse and TA-Coarse-1.
  • the difference between coarse synchronization and fine synchronization is that the coarse synchronization is the step size in which the symbol is the synchronous search, and the fine synchronization is the step size in which the sampling point is the synchronous search.
  • FIG. 6a and 6b An example of the coarse synchronization and fine synchronization implementation of the method of the present invention is shown in Figures 6a and 6b.
  • the window size Window_Size 3N
  • the position of the symbol is i.
  • the shaded portion is the range of energy sums at which the channel parameter estimates need to be calculated.
  • the window size is increased by the step size N; in addition, the symbol position varies by [0, N h -1].
  • the shaded portion is the range of energy sums at which the channel parameter estimates need to be calculated.
  • fine synchronization uses sample points as the step size for synchronous searches. The sampling point position varies from [(TA_Coarse-l)xN+l, TA_CoarsexN].
  • Figure 7 is a schematic diagram of the 8PSK subset splitting of the method of the present invention.
  • the purpose of the subset splitting is to divide the 8PSK signal into a smaller number of states and create a grid map based on this state.
  • 8PSK is divided into two subsets, which are represented as subset 0 and subset 1.
  • Subset 0 contains the symbols 1, 3, 5, 7; and subset 1 contains the symbols 0, 2, 4, 6.
  • subset 0 contains symbols 1, 5; subset 1 contains symbols 3, 7; subset 2 contains symbols 0, 4; subset 3 contains Symbol 2, 6.
  • the present invention proposes an adaptive 8PSK equalization demodulation method for the EDGE system, that is, the joint estimation is first based on the estimated channel parameter values, and the time advance of the signal is simultaneously determined by the two steps of coarse synchronization and fine synchronization. And the dispersion length of the channel, and then based on the dispersion length, adaptively adopts a reduced state method for 8PSK equalization demodulation according to a predetermined criterion; compared with the conventional method, the method of the invention satisfies the EDGE protocol specification Under the premise, the performance of the baseband system when the actual channel dispersion length is relatively small is improved, and the performance of the baseband system is also guaranteed when the channel dispersion length is relatively large.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Power Engineering (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)

Abstract

L'invention concerne un procédé de démodulation 8PSK adaptative dans un système EDGE, dans lequel : un module d'inversion du signal inverse les signaux I et Q reçus à taux d'échantillonnage multiple ; un module d'estimation de paramètre de canal opère un décalage par rapport au signal inversé et obtient la valeur d'estimation de paramètre de canal à un taux d'échantillonnage multiple ; une estimation associée est réalisée en fonction de la valeur d'estimation du paramètre de canal ; une valeur « time preact » du signal et la longueur de dispersion actuelle du canal sont déterminés de façon simultanée par synchronisation brute et par synchronisation précise ; une synchronisation et un échantillonnage par abaissement sont appliqués au signal inversé ; un filtrage adapté est appliqué au signal synchronisé et échantillonné par abaissement ; une démodulation 8PSK est réalisée de manière adaptative par état réduit en fonction des règles prédéterminées. Le procédé de l'invention permet d'améliorer les performances du système de bande de base lorsque la longueur de la dispersion actuelle du canal est inférieure et permet de maintenir les performances du système de bande de base inchangée lorsque la longueur de la dispersion du canal est supérieure, afin de répondre aux spécifications du protocole EDGE.
PCT/CN2005/002438 2005-12-31 2005-12-31 Procede de demodulation 8psk dans un systeme edge WO2007076638A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
CN2005800518664A CN101292485B (zh) 2005-12-31 2005-12-31 适用于edge系统的自适应8psk解调的方法
PCT/CN2005/002438 WO2007076638A1 (fr) 2005-12-31 2005-12-31 Procede de demodulation 8psk dans un systeme edge
BRPI0520826A BRPI0520826B1 (pt) 2005-12-31 2005-12-31 método de demodulação adaptável 8psk no sistema edge

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101662389B (zh) * 2009-10-19 2012-04-18 杭州华三通信技术有限公司 一种统计性能数据的方法及装置
CN102739582A (zh) * 2012-06-27 2012-10-17 京信通信系统（广州）有限公司 适用于无线信道的均衡接收方法及系统
CN103001899A (zh) * 2011-09-15 2013-03-27 京信通信系统（中国）有限公司 用于gsm通信系统的自适应均衡解调方法及装置

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Publication number Priority date Publication date Assignee Title
US5644603A (en) * 1994-07-07 1997-07-01 Nec Corporation Maximum-likelihood sequence estimator with variable number of states
CN1142689C (zh) * 2001-04-18 2004-03-17 上海大唐移动通信设备有限公司 一种适用于edge系统的8psk均衡解调实现方法

Patent Citations (2)

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Publication number Priority date Publication date Assignee Title
US5644603A (en) * 1994-07-07 1997-07-01 Nec Corporation Maximum-likelihood sequence estimator with variable number of states
CN1142689C (zh) * 2001-04-18 2004-03-17 上海大唐移动通信设备有限公司 一种适用于edge系统的8psk均衡解调实现方法

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Title
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101662389B (zh) * 2009-10-19 2012-04-18 杭州华三通信技术有限公司 一种统计性能数据的方法及装置
CN103001899A (zh) * 2011-09-15 2013-03-27 京信通信系统（中国）有限公司 用于gsm通信系统的自适应均衡解调方法及装置
CN102739582A (zh) * 2012-06-27 2012-10-17 京信通信系统（广州）有限公司 适用于无线信道的均衡接收方法及系统
CN102739582B (zh) * 2012-06-27 2015-08-12 京信通信系统（广州）有限公司 适用于无线信道的均衡接收方法及系统

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CN101292485A (zh) 2008-10-22
BRPI0520826B1 (pt) 2018-11-13
CN101292485B (zh) 2011-03-02

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