WO2008011745A1 - Procédé de démodulation de signaux de réception de liaisons descendantes et procédé optimisé associé d'attribution de voies - Google Patents

Procédé de démodulation de signaux de réception de liaisons descendantes et procédé optimisé associé d'attribution de voies Download PDF

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Publication number
WO2008011745A1
WO2008011745A1 PCT/CN2006/001423 CN2006001423W WO2008011745A1 WO 2008011745 A1 WO2008011745 A1 WO 2008011745A1 CN 2006001423 W CN2006001423 W CN 2006001423W WO 2008011745 A1 WO2008011745 A1 WO 2008011745A1
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WO
WIPO (PCT)
Prior art keywords
path
effective
multipath
allocated
despreading
Prior art date
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PCT/CN2006/001423
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English (en)
Chinese (zh)
Inventor
Guan Chen
Xinxi Diao
Original Assignee
Zte Corporation
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 Zte Corporation filed Critical Zte Corporation
Priority to PCT/CN2006/001423 priority Critical patent/WO2008011745A1/fr
Priority to CN2006800502548A priority patent/CN101351979B/zh
Publication of WO2008011745A1 publication Critical patent/WO2008011745A1/fr

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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
    • H04B1/7097—Interference-related aspects
    • H04B1/711—Interference-related aspects the interference being multi-path interference
    • 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
    • H04B1/7117—Selection, re-selection, allocation or re-allocation of paths to fingers, e.g. timing offset control of allocated fingers
    • 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

Definitions

  • the present invention relates to a downlink receiving technology in a CDMA wireless communication system, and in particular, to a demodulation method for a CDMA downlink received signal : a method and a multipath allocation method thereof.
  • signals transmitted by a base station to respective users are synchronously orthogonal.
  • inter-path interference is introduced.
  • a small spreading factor is used, such inter-path interference causes reception. Performance is more likely to cause floor effects.
  • Literature [3] proposed a symbol-level generalized Rake receiving method called g-Rake.
  • the disadvantage of chip-level equalization is that the operation is at the chip level, so the amount of computation is too high.
  • the symbol-level processing method that can have the same performance g-Rake also has the disadvantage of too high computational complexity when the number of channel paths is large.
  • the calculation of the interference correlation matrix in the g-Rake method makes the calculation more complicated by considering the influence of the receiving shaping filter. Summary of the invention
  • the technical problem to be solved by the present invention is to propose an optimization method for multipath allocation in a CDMA downlink generalized Rake receiver. Under the condition that the number of multipath despreading paths is limited, the multipath allocation is optimally configured, thereby obtaining Optimal performance in this case.
  • the present invention provides an optimization method for multipath allocation in a CDMA downlink generalized Rake receiver, which includes the following steps:
  • the multipath despreading resources are allocated to L effective multipaths, and the remaining M-L multipath despreading resources are preferentially allocated to the virtual paths allocated between the effective multipaths with the highest SNR.
  • the above method may also have the following features:
  • step (d) it is assumed that the L effective multipaths are arranged according to the signal to noise ratio from large to small as follows:
  • the remaining M-L multipath despread resources are allocated as follows:
  • step (d3) If the multipath despreading resource has been allocated, or all valid paths have been added to the effective path set, end, otherwise, return to step (d2). Further, the above method may also have the following features:
  • step (dl) when the virtual path between the two strongest paths is allocated, the virtual path of the weak path relative to the strong path is preferentially assigned, and the virtual path of the strong path ⁇ relative to the weak path r 2 is redistributed;
  • step (d2) when the virtual path between the newly added effective path ⁇ and the original effective path ⁇ r 2 ,.”, r M is allocated, the virtual path of ⁇ is sequentially assigned, and then Allocating the original effective path W", ! ⁇ with respect to the virtual path of the ⁇ ,.
  • each time a virtual path is successfully assigned it is judged whether the multipath despreading resource has been allocated, and if it has been allocated, the allocation is terminated immediately; otherwise, the virtual path allocation is continued.
  • the technical problem to be solved by the present invention is to propose a demodulation method for a CDMA downlink received signal.
  • the multipath allocation is optimally configured, thereby obtaining the most Excellent performance.
  • the present invention provides a method for demodulating a CDMA downlink received signal, which includes the following steps:
  • the L effective multipaths are arranged according to the signal to noise ratio from large to small as follows:
  • the remaining M-L multipath despread resources are allocated as follows:
  • (B1) first allocate the virtual path between the effective path sets of the two strongest paths ⁇ 72 ⁇ , for example, if the multipath despreading resource has been allocated, the process ends; otherwise, the next step is performed;
  • step ( ⁇ 3) If the multipath despreading resource has been allocated, or all valid paths have been added to the effective path set, end, otherwise, return to step ( ⁇ 2).
  • the above method may also have the following features:
  • step (B1) when the virtual path between the two strongest paths is allocated, the virtual path of the weak path relative to the strong path is preferentially assigned, and the virtual path of the weak path is compared with the virtual path of the weak path of 7: 2 ;
  • step ( ⁇ 2) when the newly added effective diameter ⁇ and the virtual path between the original effective paths ⁇ .”, ⁇ are allocated, r is sequentially assigned ; relative to ⁇ , 2 , ⁇ , ⁇ ⁇ virtual path, and then assign the original effective path, ⁇ 2 , ⁇ , ⁇ ⁇ relative to the virtual path of ⁇ ;
  • each time a virtual path is successfully assigned it is judged whether the multipath despreading resource has been allocated, and if it has been allocated, the allocation is terminated immediately; otherwise, the virtual path allocation is continued.
  • the above method may also have the following features:
  • the step (D) is to calculate the interference correlation matrix by the following formula:
  • R MW refers to the interference correlation matrix of other users without amplitude information, N.
  • N refers to the power of thermal noise, N.
  • R FL is a thermal noise correlation matrix.
  • the thermal noise ⁇ ⁇ is calculated by:
  • the above method may also have the following features:
  • the thermal noise is calculated by:
  • R MUI ( d iA) E [ymi ( d i )y M ui ( d i )]
  • 4 ⁇ 2 are the delays for allocating multipath
  • R MW « ⁇ 2 ) is the correlation value of the multiple access interference without the amplitude information of the diameter and the diameter
  • E[.] indicates the mathematical expectation
  • (d 2 ) represents the conjugate of the descrambling despreading symbol of the diameter d 2 without amplitude information
  • N is the spreading factor used by the target user, respectively representing the path
  • the channel fading coefficients of the / and the diameters represent the delays of the diameter/sum diameter, respectively.
  • the invention proposes a novel adaptive Rake receiver, which adopts an optimal multipath allocation scheme, and can obtain the best performance when the multipath despreading resources are limited. Further, the present invention can also provide a novel method for calculating the interference correlation matrix in the g-Rake receiver, which greatly reduces the amount of calculation and can achieve the symbol level equalization effect.
  • the present invention is more suitable for downlink reception of a CDMA system, i.e., applied to a user terminal (UE:).
  • Figure 1 is a schematic illustration of an example of an effective path and a virtual path of the present invention.
  • 2 is a general flow chart of multipath distribution in accordance with an embodiment of the present invention.
  • FIGS 3a to 3c are schematic views of an example of multipath distribution of the present invention. Preferred embodiment of the invention
  • the multipath search is performed first, then the channel estimation is performed, then the multipath allocation is performed, and the descrambling and despreading is performed according to the result of the multipath allocation, and finally It is a generalized Rake reception.
  • the process is as shown in FIG. 2, and includes the following steps: Step 10: After receiving the baseband digital IQ signal, the CDMA downlink receiver first performs multipath search, searches for L effective multipaths, and performs the L effective multipaths. Channel estimation, obtaining channel estimation value column vector A;
  • Step 20 Perform multipath allocation according to the assignable multipath despreading resource M, and the multipath allocation strategy can obtain an optimal configuration when the number of multipath despreading paths is limited, and the specific method will be described in detail below;
  • Step 30 performing multipath descrambling and despreading on the allocated path to obtain a despreading vector for the target symbol;
  • Step 40 Calculate the interference correlation matrix R u according to the interference R MUI and the thermal noise R n of other users;
  • the virtual path refers to the symmetrical position of one effective multipath relative to the other effective multipath
  • the assignable virtual path refers to the virtual path and any other effective multipath or assigned virtual path.
  • the distance must be greater than or equal to one chip.
  • L is the number of effective multipaths searched by the multipath searcher.
  • ⁇ is called the path ⁇ ] relative to the virtual path of the path; where r, and ⁇ ,. are the effective multipaths searched by the multipath searcher.
  • FIG 1 there are two effective multipaths P1 and P2.
  • the horizontal direction represents the time delay of the diameter; the vertical direction represents the signal-to-noise ratio (strength) of the diameter.
  • the path P2 delay is larger than P1, but the signal-to-noise ratio is weaker than P1.
  • the diameter P2—1 is indicated by a dotted line, indicating that it is a virtual path and is the virtual path of the diameter P2 relative to P1.
  • P2 - 1 and P2 are symmetric about the center of P1.
  • this embodiment proposes the following allocation strategy: Assume that the available multipath despreading resources are M;
  • the multipath despreading resources are allocated in the conventional manner, and all the multipath despreading resources are allocated to the M effective paths with the highest signal to noise ratio among the L effective paths; g-Rake is equivalent For conventional Rake receivers.
  • the multipath despreading resource is preferentially assigned to the effective multipath L, and the remaining ML are allocated.
  • the multipath despreading resource is preferentially allocated to the virtual path allocated between the effective multipaths with the highest signal to noise ratio.
  • the assignable virtual path M-L is determined by the following iterative method:
  • the assignable virtual path in the set is preferably as follows Sequence generation:
  • the virtual path of the weak path relative to the strong path is preferentially assigned; for example, the virtual path of the set ⁇ is assigned as follows: the virtual path of the weak path r 2 relative to the strong path ⁇ is first assigned; the redistributed strong path ⁇ is relative to the weak path ⁇ 2 Virtual path; each time a virtual path is successfully assigned, the total number of virtual paths that have been allocated is L tes p 1 , and if L test ⁇ ML, the virtual path allocation continues; otherwise, the allocation is terminated.
  • the assigned virtual paths are recorded in the virtual path set in the order of allocation; if the number of assignable virtual paths L test ⁇ ML in the set ⁇ r 15 r 2 ⁇ , then the strongest path in the remaining path is added to the set, ie r 3 , form the set ⁇ , r 2 , r 3 ⁇ ; continue to assign the virtual path downwards, the principle is still to assign the virtual path of the weak path relative to the strong path, ie:
  • Figure 3a shows the effective path distribution of the actual multipath search; the longitudinal representation of the diameter; the lateral representation of the delay.
  • the path delay satisfies the relationship: P1 ⁇ P2 ⁇ P3;
  • the path signal to noise ratio satisfies the relationship: P2>P1>P3;
  • Figures 3b and 3c show the process of virtual path assignment.
  • the number inside the circle indicates the assigned sequence number.
  • the virtual diameter P1-2 of the sub-strong diameter P1 with respect to the strongest diameter P2 is first allocated; the virtual diameter P2-1 of the strongest diameter P2 with respect to the sub-strong path P1 is redistributed, as shown by the dotted line in the figure. It is a virtual path.
  • the virtual path P3-2 of P3 relative to P2 is redistributed. However, this virtual path coincides with the originally assigned virtual path P2_l, so the virtual path P3-2 is not established and discarded. Then assign the virtual path of P3 relative to P1, and so on.
  • the effective path delay set of the multipath search is ⁇ 0, 1, 6 ⁇ , and the signal-to-noise ratio of the path is arranged in descending order, with three effective paths.
  • the virtual path set obtained by the above calculation is: ⁇ -1 ⁇ . If the total path despreading resource that can be allocated is 5, then two virtual paths need to be allocated. The virtual path set is: ⁇ -1, 2 ⁇ ; if the total path despread resource that can be allocated is 6, then three are allocated.
  • the virtual path, the virtual path set is: ⁇ -1, 2, -6 ⁇ ;
  • the present embodiment proposes a calculation method that simplifies the interference correlation matrix by ignoring the influence of the receiving and transmitting shaping filters.
  • the interference correlation matrix Ru is decomposed into three parts: the user's own interference correlation matrix (without amplitude information) R ISI , the interference correlation matrix of other users (without amplitude information) R MUI , thermal noise (including Interval interference) Correlation matrix (without amplitude information) R n , then you can ignore si, the remaining two can be obtained as follows:
  • r s represent the delay of the diameter/and diameter, respectively.
  • thermal noise including inter-cell interference
  • ⁇ without amplitude information
  • the interference correlation matrix can be obtained by:
  • N the total power that interferes with the user.
  • NoR n - is the correlation matrix of thermal noise.
  • the optimal multipath merge weights are:
  • h a channel estimation value column vector
  • y a despreading column vector of each path for the target symbol.
  • the above formula (3) (4) (5) can be referred to the literature [3].
  • only the optimization method of the above multipath allocation may be adopted in the demodulation process, and a conventional algorithm is adopted for the interference correlation matrix. it is also fine.
  • the method of the invention can be applied to a novel adaptive Rake receiver, adopting an optimal multipath allocation scheme, and obtaining optimal performance in the case where the multipath despreading resources are limited. Further, the present invention also proposes a novel simplified method for calculating the interference correlation matrix in the g-Rake receiver, which greatly reduces the amount of calculation and can achieve the symbol level equalization effect.
  • the present invention is more suitable for downlink reception of a CDMA system, i.e., applied to a user terminal (UE:).

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

Abstract

L'invention porte sur un procédé de démodulation de signaux de réception de liaisons descendantes AMCR et sur un procédé optimisé associé d'attribution de voies consistant à rechercher des voies à L efficace en utilisant un signal numérique à bande de base et à y appliquer une estimation de canal pour obtenir le vecteur h de la colonne de valeurs d'estimation de canal. Lors de l'exploitation de l'attribution de voies, si la ressource attribuée de désétalement des voies M<=L, on attribue toutes les ressources de désétalement des voies aux voies efficaces. Si M>L, on attribue d'abord la ressource de désétalement aux voies efficaces L, et les ressources en voies M-L restantes de désétalement des voies de préférence à des voies virtuelles choisies parmi celles ayant le rapport S/B le plus élevé. On effectue ensuite un désembrouillage et un désétalement des voies attribuées obtenues, puis on obtient un vecteur h de colonne de désétalement du symbole objet, puis on calcule une pondération combinée des voies avec ladite matrice associée de désembrouillage et le vecteur de la colonne de valeur d'estimation de canal, puis enfin on calcule le symbole de l'objet démodulé. Si le nombre de voies désétalées est limité, l'invention obtient une configuration optimale d'attribution de voies.
PCT/CN2006/001423 2006-06-22 2006-06-22 Procédé de démodulation de signaux de réception de liaisons descendantes et procédé optimisé associé d'attribution de voies WO2008011745A1 (fr)

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PCT/CN2006/001423 WO2008011745A1 (fr) 2006-06-22 2006-06-22 Procédé de démodulation de signaux de réception de liaisons descendantes et procédé optimisé associé d'attribution de voies
CN2006800502548A CN101351979B (zh) 2006-06-22 2006-06-22 Cdma下行接收信号的解调方法及其多径分配的优化方法

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PCT/CN2006/001423 WO2008011745A1 (fr) 2006-06-22 2006-06-22 Procédé de démodulation de signaux de réception de liaisons descendantes et procédé optimisé associé d'attribution de voies

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Cited By (1)

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CN102118329A (zh) * 2011-03-25 2011-07-06 华为技术有限公司 多天线系统中的干扰消除方法和装置

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CN107959513B (zh) * 2016-10-13 2019-11-22 大唐移动通信设备有限公司 一种采用时延参数进行测距的方法和装置
CN110518921B (zh) * 2018-05-21 2021-05-04 北京小米松果电子有限公司 多径合并的方法、装置和存储介质以及电子设备

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CN1182986A (zh) * 1996-08-23 1998-05-27 Ntt移动通信网株式会社 瑞克接收机
JP2000232430A (ja) * 1999-02-08 2000-08-22 Nec Corp Ｒａｋｅ（熊手）受信機
JP2001223613A (ja) * 2000-02-14 2001-08-17 Nec Corp スペクトラム拡散通信方式受信機およびスペクトラム拡散通信のパスサーチ方法
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CN101351979B (zh) 2012-06-13
CN101351979A (zh) 2009-01-21

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