CN1543108A - Multi-path combining method for WCDMA communication system - Google Patents
Multi-path combining method for WCDMA communication system Download PDFInfo
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- CN1543108A CN1543108A CNA2003101039890A CN200310103989A CN1543108A CN 1543108 A CN1543108 A CN 1543108A CN A2003101039890 A CNA2003101039890 A CN A2003101039890A CN 200310103989 A CN200310103989 A CN 200310103989A CN 1543108 A CN1543108 A CN 1543108A
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Abstract
This invention discloses a multichannel merge method used in WCDMA. Firstly, the broadband spread spectrum signal input to RAKE receiver is de-scrambled and de-spread then the pilot symbols are taken out from a special physical control channel for de-relational operation to get the initial channel estimation values of the pilot symbol, again then said values are coherently integrated and filtered and to get the final estimation value of every pilot symbol and to carry out multichannel merge. This invention overcomes the shortcomings of difficult threshold set resulting in error- multipath filtration so that environment change does not influence the selection of threshold.
Description
Technical field
The present invention relates to the multipath merging method of wireless communication system, the up multipath merging method of particularly a kind of Wideband Code Division Multiple Access (WCDMA) (WCDMA) communication system.
Background technology
Along with the fast development of mobile communication, people require also more and more higher to the quality of mobile communication and the type of service that provides thereof, and the proposition of 3G (Third Generation) Moblie and development have met people's this demand just, therefore get most of the attention.Wideband Code Division Multiple Access (WCDMA) (WCDMA) is (the 3rd Generation Partnership Project of 3-G (Generation Three mobile communication system) standardization body, 3GPP) the Radio Transmission Technology of Ti Chuing (Radio Transmission Technology, RTT) scheme, it not only can provide high-quality voice service, and can provide and the similar multimedia service of fixed network.In Wideband Code Division Multiple Access (WCDMA) (WCDMA) system, in order to improve uplink quality, in receiver, adopt rake receiver scheme to make systematic function reach the highest, the rake receiver is exactly respectively to the demodulation respectively of different multipaths, channel estimation process, again different multipaths is effectively merged to get up by multipath merging method at last, thereby effectively anti-multipath is disturbed, improve the performance of communication system greatly.As shown in Figure 1, multipath merges and mainly comprises two parts, at first be to select effective diameter through certain method, promptly filter out noise path (false footpath), be effective diameter to be merged then by certain method, the method that the latter substantially adopts high specific to merge, the former then has than multi-method and realizes.Multipath merging method of the present invention is to select the improvement of effective diameter method during multipath is merged.
At present, the normal multipath merging method of using mainly contains absolute gate method and the relative threshold method based on energy.Absolute gate method is exactly the interior average energy of certain hour scope that calculates noise path, be worth as thresholding with bigger certain of this energy, what surpass this thresholding just thinks effective diameter, this method implements fairly simple, but thresholding is set bad assurance, at first must estimate the energy of noise path, be the reference settings thresholding in proper order, if differentiating, the too high true footpath that some are more weak easily of threshold setting becomes false footpath, if threshold setting is too low, be easy to the footpath that comes true is directly differentiated in vacation, the both can make systematic function reduce.The relative threshold method then is by energy ordering with all footpaths, obtain ceiling capacity, then with certain percentage result of this energy as thresholding, it is also fairly simple that this method implements, but same performance is not so good, mainly is the bad setting of percentage, if be provided with too high, then almost have only the ceiling capacity footpath to pass through, remaining will be filtered out when the footpath that rehearses, and makes the footpath of moderate strength also be easy to be filtered; If be provided with too low, can be with vacation directly as true footpath, especially different multipaths is through different wireless channels, it is different to decline, it is also different to delay time, and this method is because fluctuations is very ill-considered many times along with the variation of ceiling capacity certain percentage result directly simply, not only that difficulty is set is big for percentage, and the error that causes multipath to filter easily.In fact, more than two kinds of methods also have a common shortcoming, when having wireless environment or system to cause the spike noise in the false footpath, will have a strong impact on systematic function exactly.
Summary of the invention
The objective of the invention is to overcome prior art exists thresholding setting difficulty to cause multipath to filter error greatly, easily, thereby have a strong impact on the shortcoming of systematic function, in the hope of propose a kind of can simply be provided with threshold value, effectively resist the spike noise jamming, improve the multipath merging method that is used for Wideband Code Division Multiple Access (WCDMA) (WCDMA) communication system of system signal receptivity.
For achieving the above object, the present invention proposes a kind of multipath merging method that is used for broadband CDMA system, it is characterized in that, may further comprise the steps:
Step 2, according to known time slot format from Dedicated Physical Control Channel (DPCCH, Dedicated Physical Control Channel) takes out frequency pilot sign, each frequency pilot sign that extracts carries out the decorrelation computing with known pilot symbols respectively, obtains the channel estimation value of each frequency pilot sign;
Step 3, according to different channel estimation methods, the channel estimation value of these frequency pilot signs is carried out coherent integration and filtering, obtain the final channel estimation value of each frequency pilot sign.Wherein channel estimation methods mainly contain the average channel estimation methods of single time slot, based on the average weighted channel estimation methods of channel estimation methods, multi-slot (the Weighted Multi-SlotAveraging that simplifies Kalman's tracking filter, WMSA) and the iterative channel estimation technique (IterativeChannel Estimation, ICE).
Step 4, multipath merge.Compensate each symbol of each DPCCH, the symbol sebolic addressing after being compensated with the final channel estimation value of each frequency pilot sign; Frequency pilot sign among the DPCCH after the compensation is carried out hard decision, and the judgement principle is if input 〉=0 output=1 else output=-1; Result behind the hard decision and desirable pilot tone compare, and add up the number of correct pilot tone in the time slot; Add up the correct total number of pilot tone in N the time slot again; , think that this directly is effective diameter, otherwise be invalid footpath during according to the ratio of the shared total pilot tone number of the total number of correct pilot tone greater than certain value; Effective diameter participates in high specific and merges, and invalid footpath does not participate in high specific and merges.
The multipath merging method that is used for Wideband Code Division Multiple Access (WCDMA) communication system of the present invention, compared with prior art, adopt pilot tone BER (Block Error Rate in certain footpath of statistics, whether situation Block Error Rate) is adjudicated is effective diameter, and needn't carry out Energy Estimation to noise, thereby make thresholding select not to be subjected to the influence of environment conversion, can resist spike interference of noise etc. effectively, improved the performance of multipath merging module effectively, significantly.
Description of drawings
Fig. 1 is the frame structure schematic diagram of WCDMA system uplink DPCH (DPCH, Dedicated PhysicalChannel);
Fig. 2 releases to remove to calculate partially schematic diagram in the channel estimating.
Fig. 3 is the concrete application system block diagram of the method for the invention.
Fig. 4 is the method for the invention flow chart figure.
Fig. 5 is the method for the invention core flow chart.
Embodiment
Describe in further detail below in conjunction with the enforcement of the drawings and specific embodiments to technical scheme of the present invention, according to following described embodiment, the technical staff in same field can be easy to realize the present invention.
What Fig. 1 represented is the frame structure of Wideband Code Division Multiple Access (WCDMA) (WCDMA) system uplink DPCH (DPCH); In order to distinguish data field among the DPDCH (Dedicated Physical DataChannel, Dedicated Physical Data Channel) and the data field among the DPCCH, the data field that identifies especially among the DPCCH is non-pilot field.
Shown in Figure 2 mainly is the inclined to one side computational process of going that is used for explaining in the channel estimating.In this embodiment, we suppose that channel estimation methods is single time slot coherent integration method.Pi is a pilot field symbols among the figure, and Ni is non-pilot field symbols, so when not going partially to calculate, be used for compensating Si (i=1 ..., 5) final channel estimation value all be
And in the channel estimation methods that partially calculates of taking, be used for compensating Si (i=1 ..., 5) final channel estimation value be
Fig. 3 is the enforcement block diagram of the multipath merging method that the present invention relates to.In this example, the analog-signal transitions that AD converter 301 will be input to receiver is that digital signal is sent into descrambling and de-spreading module 304, each bar multipath scrambler that descrambling and de-spreading module 304 utilizes code tracking device 302 and code generator 303 to produce carries out descrambling and de-spreading to input signal, and each multipath signal behind the descrambling and de-spreading sent into its corresponding channel estimating and compensating module 305, channel estimating and compensating module 305 calculate the final channel estimation value in the corresponding moment of each symbol of DPCCH respectively and dedicated channel DPDCH are compensated, calculate the corresponding final channel estimation value that calculates partially and DPCCH compensated of taking constantly of each symbol of DPCCH more respectively, each footpath signal after the compensation outputs to multipath merging module 306 and merges, signal after will merging at last is input to and carries out deinterleaving and decoding in deinterleaving/decoder 307, obtains the primary signal of transmitting terminal emission.The position of the multipath merging method that the present invention proposes in implementing block diagram is mainly to merge module 306 at multipath, and channel estimation module 305 should have the relevant inclined to one side calculating of going with it certainly.
Fig. 4 is the flow chart that adopts multipath merging method of the present invention.
This logic flow starts from step 401, ends at step 405.
The wideband spread-spectrum signal of step 401 pair input RAKE receiver carries out descrambling and de-spreading.
Order enters step 402, obtains all frequency pilot signs of DPCCH from 401 output.Relevant with desirable pilot tone respectively, obtain the channel estimation value of each frequency pilot sign.
Order enters step 403, add and go inclined to one side calculating, according to the requirement of channel estimating concrete grammar, obtain the corresponding final channel estimation value constantly of each frequency pilot sign, be used in the channel compensation block among the present invention compensating DPCCH pilot field symbols must use the final channel estimation value that calculated partially through the past.Compensation for the symbol of the symbol of non-pilot field among the DPCCH and DPDCH, also can be directly with this value compensation, also the final channel estimation value that can calculate partially with not taking compensates, and is the same substantially the symbol of the two non-pilot field in DPCCH and the symbol of DPDCH.Here explained adding the reason of going to calculate partially, in common channel estimation methods, obtain being used for compensating in the channel estimation value of each frequency pilot sign, this frequency pilot sign factor that has comprised certain ingredients, have among the result after the compensation this frequency pilot sign square composition, this can to the compensation after hard decision cause to a certain degree erroneous effects; Ask the final channel estimation value of certain pilot tone in channel estimation methods, promptly between coherent integration, time slot in the filtering, we can not count this pilot tone.We claim this to remove the inclined to one side calculating of being calculated as of this pilot tone.
Order enters step 404, compensates DPCCH and DPDCH symbol respectively with the 403 final channel estimation values that obtain.Result after each multipath compensation exports to multipath and merges module.
Order enters step 405, to doing hard decision process from the pilot symbol among 403 the DPCCH, compare with desirable pilot symbol again, obtain the correct number of this time slot pilot demodulation, just obtain the BER of Pilot, FIR (Finite ImpulseResponse through certain-length, finite impulse response) filtering, perhaps can add up the number of the correct pilot in the certain hour length, such as 10slots or 15slots,,, this directly contains signal even being described because when correct pilot only accounts for 50%, but should not participate in merging yet, because signal to noise ratio is too low, we can account for total 60%--70% as a thresholding with the correct pilot of demodulation, determine whether this footpath is effective: effectively the maximum module that merges is exported in the footpath, invalid footpath does not participate in, and the result that high specific merges exports to the decoder module.
Fig. 5 is equivalent to step 405, it is the detail flowchart of step 405, be the core of the multipath merging method that the present invention relates to, describe the pilot tone of how both utilizing after the channel estimating compensation of calculating partially in detail and judge whether multipath is the method for effective diameter through the past.This logic flow starts from step 501, ends at step 506.
The multipath merging method that adopts invention to set forth, needn't estimate noise, the selection of thresholding is not subjected to the influence of environment conversion, the selection of thresholding is very easily simple, can also resist spike interference of noise or the like advantage effectively, improve multipath effectively, significantly and merged the performance of module, thereby can improve the receptivity of communication system greatly.Simulation result shows, no matter when translational speed is still fast slowly, the performance of the multipath merging method that the present invention sets forth all is significantly improved than the performance of the multipath merging method of prior art.
Claims (5)
1, a kind of multipath merging method that is used for broadband CDMA system is characterized in that, may further comprise the steps:
Step 1, to the input RAKE receiver wideband spread-spectrum signal carry out descrambling and de-spreading;
Step 2, take out frequency pilot sign according to known time slot format from Dedicated Physical Control Channel, each frequency pilot sign that extracts carries out the decorrelation computing with known pilot symbols respectively, obtains the channel estimation value of each frequency pilot sign;
Step 3, according to different channel estimation methods, the channel estimation value of these frequency pilot signs is carried out coherent integration and filtering, obtain the final channel estimation value of each frequency pilot sign;
Step 4, carry out multipath and merge.
2, according to claim 1 in the multipath merging method of broadband CDMA system, it is characterized in that the channel estimation methods in the described step 3 is mainly: the average channel estimation methods of single time slot, based on the average weighted channel estimation methods of channel estimation methods, multi-slot and the iterative channel estimation technique of simplifying Kalman's tracking filter.
3, according to claim 1ly it is characterized in that in the multipath merging method of broadband CDMA system described step 4 further may further comprise the steps:
The first step: take out the pilot symbol in the Dedicated Physical Control Channel, do hard decision;
Second step: produce local desirable frequency pilot sign according to time slot format;
The 3rd step: the frequency pilot sign that the demodulation that obtains behind the hard decision in the more local desirable pilot tone and the first step is come out, if identical output 1, if different output 0;
The 4th step: with a sliding window, the ratio of the correct demodulation of pilot and export to next procedure in the statistical window;
The 5th step: set a thresholding, can be set at certain value of 60-75%, if input 〉=Threshold output=1 else output=0;
The 6th step: determine current slot or frame whether to participate in high specific according to the indicated value of the whether effective diameter of the 5th step output and merge; If the 5th step output 1 then participate in high specific and merge, on the contrary, if the 5th step output 0 then do not participate in high specific and merge.
4, according to claim 2ly it is characterized in that in the multipath merging method of broadband CDMA system the judgement principle of hard decision is in the described first step: if input 〉=0output=1 else output=-1.
5, according to claim 2ly it is characterized in that the length of the sliding window in described the 4th step is got 5-15slots even longer in the multipath merging method of broadband CDMA system.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008031340A1 (en) * | 2006-09-08 | 2008-03-20 | Huawei Technologies Co., Ltd. | A method and device for transmitting and receiving signal |
| CN1819568B (en) * | 2006-03-02 | 2010-09-29 | 上海宣普实业有限公司 | Merging and normalizing method and device with down channel estimation in assigned distributing mode by user |
| CN101110605B (en) * | 2006-07-20 | 2010-12-08 | 中兴通讯股份有限公司 | Rick receiving set for emitter power control data and method thereof |
| CN101141143B (en) * | 2007-09-04 | 2011-05-11 | 中兴通讯股份有限公司 | Time-frequency RAKE receiving method and apparatus |
| CN1819569B (en) * | 2006-03-02 | 2011-05-18 | 上海宣普实业有限公司 | Merging and normalizing method and device with down channel estimation in default distributing mode |
| CN101667845B (en) * | 2008-09-05 | 2013-03-20 | 中兴通讯股份有限公司 | Self-adapting combination method and self-adapting combination system for multi-channel signals |
-
2003
- 2003-11-04 CN CN 200310103989 patent/CN1260900C/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1819568B (en) * | 2006-03-02 | 2010-09-29 | 上海宣普实业有限公司 | Merging and normalizing method and device with down channel estimation in assigned distributing mode by user |
| CN1819569B (en) * | 2006-03-02 | 2011-05-18 | 上海宣普实业有限公司 | Merging and normalizing method and device with down channel estimation in default distributing mode |
| CN101110605B (en) * | 2006-07-20 | 2010-12-08 | 中兴通讯股份有限公司 | Rick receiving set for emitter power control data and method thereof |
| WO2008031340A1 (en) * | 2006-09-08 | 2008-03-20 | Huawei Technologies Co., Ltd. | A method and device for transmitting and receiving signal |
| CN101141214B (en) * | 2006-09-08 | 2012-12-19 | 华为技术有限公司 | Signal transmitting-receiving method and apparatus |
| CN101141143B (en) * | 2007-09-04 | 2011-05-11 | 中兴通讯股份有限公司 | Time-frequency RAKE receiving method and apparatus |
| CN101667845B (en) * | 2008-09-05 | 2013-03-20 | 中兴通讯股份有限公司 | Self-adapting combination method and self-adapting combination system for multi-channel signals |
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| CN1260900C (en) | 2006-06-21 |
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