CN1719759B

CN1719759B - Timing deviation detecting and compensating method for use in CDMA system

Info

Publication number: CN1719759B
Application number: CN2005100258033A
Authority: CN
Inventors: 王炳立; 李兴伟; 叶远; 谢一宁
Original assignee: SHANGHAI XUANPU INDUSTRIAL Co Ltd
Current assignee: Shanghai Xuanpu Industrial Co., Ltd.
Priority date: 2005-05-13
Filing date: 2005-05-13
Publication date: 2012-03-21
Anticipated expiration: 2025-05-13
Also published as: CN1719759A

Abstract

This invention provides a timing deviation test compensation method in CDMA system. When a timing follow up system tests that a current timing deviation exists, it computes and outputs related T<off> to a receiving device apart from following up this T<off> based on an ordinary following up process, thus, when a timing regulating error influencing the performance appears, the timing regulating system outputs a timing error vector and uses it to pre-regulate the received timing of the system to maintain the performance of the receiving system.

Description

The detection of timing offset and compensation method in the code division multiple access system

Technical field

The present invention is that the timing offset in a kind of code division multiple access (CDMA) communication system detects and compensation method, is exactly to relate to detection and compensation method at the timing offset of TD-SCDMA system specifically.

Background technology

In the receiving system of CDMA,, must obtain chip timings and symbol timing accurately in order to obtain good reception.Because receiving system is in the continuous moving process; Channel situation will constantly change; Need the variation of the continuous tracking system time delay of timing tracking system of receiving system, for receiver provides regularly adjustment instruction accurately, to satisfy the requirement of receiving system.

In tracking regularly and adjustment process, for the performance that can take into account receiver and the stability of regularly adjusting, regulating the speed of timing system is very slowly.But so regularly in the adjustment process of the transient state of adjustment; The phenomenon that the performance that etching system receives in the time of can appearing at some reduces; Be in the process of occurrence timing adjustment; Because regularly the speed of adjustment is slow, the continuous timing error that is in course of adjustment of meeting, the situation that it might cause connection failure or receptivity to reduce.Especially current when only having individual paths to exist; And this paths is when being positioned at the sampled point front of tracking; Position according to the acceptance point of current setting will cause receiving timing error, and this type timing error also can cause the faults and the mistake that causes route searching of displacement series simultaneously.Because it is very slow regularly to regulate the speed; When the timing offset of needs adjustment is very big; Timing tracking system needs the time more of a specified duration to regulate could obtain correct timing, like this in adjustment process of this timing, and the mistake of this lasting long timing; The serious decline of receptivity can be caused, even the connection failure of Radio Link might be caused.The inefficacy of the reception that causes for fear of the tracking of in this case timing need compensate deviation regularly, to keep the normal communication of Radio Link.

Summary of the invention

Technical problem to be solved by this invention is to provide the detection method of the timing offset compensation in the code division multiple access system; Be exactly for fear of in the process of adjustment; When the error of the adjustment of the timing that influences performance occurs; By timing Adjustment System output timing error vector; The reception that receiving system uses this error vector pre-adjustment system regularly to keep the performance of receiving system, overcomes the performance loss that in the transient process of regularly adjustment, caused by timing error and the phenomenon of Radio Link connection failure.

This method specifically describes as follows: when timing tracking system detect reliably current when existing timing offset to exist, i.e. T ₀≠ T, T in the formula ₀It is the trace point position; The position of this trace point preestablishes and obtains; And in the system of reality, change according to relevant actual channel conditions, paths in-position or equivalent in-position headed by the T, satisfying simultaneously only has an active path to exist and regularly trace point is dropped in this path; Perhaps have many active paths to exist, and this path power of dropping on regularly the path of trace point front less than the power that drops on the path within the estimating window and certain predefined multiple in; Perhaps T＞T ₀+ W, wherein W is the estimating window length of the maximum that can support of system, then timing tracking system also can calculate and export relevant timing offset T simultaneously except following the tracks of this deviation regularly according to the tracing process of normal timing _OffGive receiving system.This timing offset is used for corrected received regularly, and compensation is because the mis-behave of the system that timing error causes.In order to keep system's stability regularly, timing system is given and is used strict Rule of judgment, can take into account the rapidity of the compensation of timing offset again in order to the stability of keeping system's adjustment regularly simultaneously.

Timing offset detects and compensation method realizes through following step:

At first, receiving system carries out channel estimating, and obtains the time delay power spectrum of channel based on channel estimation calculation; And set one based on the time delay power spectrum that obtains based on certain criterion and search for thresholding; Peak value based on the routing information of relevant arrival, is sought in the path that promptly is considered to effective arrival that surpasses this thresholding in the part; Promptly search the accurate due in that reaches the path, and the number in the path of confirming successively effectively to arrive and due in accurately;

Secondly, judge based on first paths in-position or equivalent in-position regularly whether the compensation sign is effective;

At last, if when regularly the compensation sign is effective, timing system will export timing adjustment information, i.e. the corresponding signal of timing error that receives of timing system output, and receiving system will have according to this error signal pre-adjustment and receive regularly the timing accuracy of assurance receiving system.

Further, described judgement regularly compensates and indicates whether effectively Rule of judgment is:

Rule of judgment 1: satisfying simultaneously only has an active path existence and this path to drop on regularly trace point; Perhaps there are many active paths to exist; And the power that the path of trace point front is dropped on regularly in this path less than the power that drops on the path within the estimating window and certain predefined multiple in the time, the compensation sign is set regularly effectively;

Perhaps, Rule of judgment 2: when first arrive the path be positioned at the trace point adding system bear estimating window and the back, the compensation sign also is set regularly effectively.

In the process that regularly compensates, the normal reception timing of the system that keeps of timing system, and actual reception regularly is exactly to add the timing offset in normal timing.Through keeping system's normal value regularly, the stability that the assurance system regularly adjusts can be avoided again because the receptivity that timing error causes descends simultaneously.

Description of drawings

Shown in Figure 1 is the flow chart of timing offset detection of the present invention and compensation method;

Fig. 2 is the sketch map of Rule of judgment shown in Figure 1;

Fig. 3 is the sketch map of Rule of judgment shown in Figure 1.

Embodiment

Timing offset as shown in Figure 1 detects and compensation method comprises the steps:

At first, the time delay power spectrum computing module 0.1 of the channel among Fig. 1 at first carries out channel estimating, and according to the time delay power spectrum that calculates channel of channel estimating; Search effectively arrives path module 0.2 and sets certain search thresholding according to the time delay power spectrum that obtains according to certain criterion, and what surpass thresholding promptly is considered to effectively arrive the path; The local peak value module 0.3 of seeking is sought peak value according to the relevant routing information that arrives in the part, i.e. search arrives the accurate due in path, and the number in the path of confirming successively effectively to arrive and due in accurately.Deliver to regularly compensating module and carry out timing compensation detection and calculating; Concrete steps are following:

Step 1, Rule of judgment 1: as shown in Figure 2, detect and whether satisfy T＜T ₀, T wherein ₀It is the trace point position; Paths in-position or equivalent in-position headed by the T; And relatively in the length of T is the window of W, do not have other many warps that effectively arrive, perhaps there are other effectively many through arriving; And satisfy every other effective arrival active path power sum and certain predefined multiple in the time, set regularly compensates and is masked as effectively;

Step 2, Rule of judgment 2: as shown in Figure 3, detect and whether satisfy T＞T ₀+ W, wherein W is the estimating window length of the maximum that can support of system, if satisfy this condition, and set regularly compensates and is masked as effectively, and set regularly compensates and be masked as effectively, withdrawing from regularly simultaneously, compensation detects step;

Step 3, when regularly the compensation sign is invalid, regularly compensating module will be closed, and this moment, regularly tracking module need not exported any timing compensated information;

Step 4, when regularly the compensation sign was effective, system then exported timing error make-up time T _Off=T-T ₀, T is that the time T of the arrival in virtual first footpath is the trace point time regularly, this time, this value was said the position of the channel estimating of correspondence corresponding to the path of first arrival by preestablishing at the beginning of the system design.

Receiving system will be according to T _OffDetermine the timing compensation rate of reception, the sampling instant that the timing Adjustment System will be exported the timing offset amount and received by this deviation of regularly adjusting decision is separated the reception timing in order to compensation, to guarantee the quality of reception in the process of whole tracking slowly.

Claims

1. the detection and the compensation method of timing offset in the code division multiple access system is characterized in that,

At first, receiving system carries out channel estimating, and obtains the time delay power spectrum of channel based on channel estimation calculation; And set one based on the time delay power spectrum that obtains based on certain criterion and search for thresholding; Peak value based on the routing information of relevant arrival, is sought in the path that promptly is considered to effective arrival that surpasses this thresholding in the part; The accurate due in the path that i.e. search arrives, and the number in the path of confirming successively effectively to arrive and due in accurately;

Secondly, judge according to first paths in-position whether regularly compensation indicates effective, judge regularly whether effective Rule of judgment is the compensation sign:

Rule of judgment 1: when in the active path of first arrival drops on regularly the window that the length that trace point front and the paths in-position of confessing one's crime rises is W, not having other effective multipaths to arrive; Perhaps;, the active path of first arrival have other effective multipaths to arrive in dropping on regularly the window that the length that trace point front and the paths in-position of confessing one's crime rises is W; And when satisfying in certain predefined multiple of the every other active path power sum of this power that drops on regularly the path of trace point front in said length is the window of W; The compensation sign is set regularly effectively, wherein W is the estimating window length of the maximum that can support of system;

Perhaps, Rule of judgment 2: be positioned at regularly the back of position of the estimating window length sum of the maximum that the trace point adding system can support when the active path of first arrival, also be provided with regularly compensate indicate effective;

At last, if when regularly the compensation sign is effective, timing system will export timing adjustment information, i.e. the corresponding signal of timing error that receives of timing system output, and receiving system will receive regularly according to this error signal pre-adjustment, the timing accuracy of assurance receiving system.

2. the detection and the compensation method of timing offset in the code division multiple access system according to claim 1; It is characterized in that; Also comprise step: when regularly the compensation sign is invalid, regularly compensating module will be closed, and this moment, regularly tracking module need not exported any timing compensated information.

3. the detection and the compensation method of timing offset is characterized in that in the code division multiple access system according to claim 1, and when regularly the compensation sign was effective, system then exported timing error make-up time T _Off=T-T ₀, T is the time T of the arrival in virtual first footpath ₀Be the trace point time regularly, this trace point time, it was corresponding to the position of the pairing channel estimating in path of first arrival by preestablishing at the beginning of the system design.