CN1163008C - Fast capture method and device for reverse random access channel - Google Patents
Fast capture method and device for reverse random access channel Download PDFInfo
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- CN1163008C CN1163008C CNB021165033A CN02116503A CN1163008C CN 1163008 C CN1163008 C CN 1163008C CN B021165033 A CNB021165033 A CN B021165033A CN 02116503 A CN02116503 A CN 02116503A CN 1163008 C CN1163008 C CN 1163008C
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Abstract
The present invention provides a fast capture method and a device for reverse random access channels based on fast Hadamard transform in a WCDMA system, which effectively utilizes the characteristics of a reverse random access channel in WCDMA. The time of correlation integral can be largely shortened and the fast capture can be realized by adopting fast Hadamard transform to replace a traditional active correlation integrator. Simultaneously, the traditional correlation integrator is replaced by the Hadamard transform, and hardware resources required by capture devices can be largely saved.
Description
(1) technical field:
The invention belongs to 3G (Third Generation) Moblie Wideband Code Division Multiple Access (WCDMA) (WCDMA) technical field, relate in particular to a kind of quick capturing method and device of reverse random access channel.
(2) background technology:
Wideband Code Division Multiple Access (WCDMA) (WCDMA) is Radio Transmission Technology (RTT) scheme that 3-G (Generation Three mobile communication system) standardization body (3rd GenerationPartnership Project (3GPP)) proposes.Catching of frequency expansion sequence is first function that receiver need be finished in the CDMA mobile communication systems, only carried out catching and following the tracks of of frequency expansion sequence, make to send the big code phase of frequency expansion sequence consistent with the code phase of local frequency expansion sequence (synchronously), could realize correct data demodulates.In actual communication systems, because the influence of multiple access interference, noise jamming and multipath effect, quick and effective frequency expansion sequence is caught and is become very difficult.Therefore, fast and effectively the frequency expansion sequence catching method is one of key technology that realizes Wideband Code Division Multiple Access (WCDMA) communication.
The catching of frequency expansion sequence is meant frequency expansion sequence that receiver receives and the phase place initial synchronisation between the local frequency expansion sequence, its importance in spread spectrum system is not only because catching and being the prerequisite of data demodulates synchronously of frequency expansion sequence is the first step of system's operation; And because the unknown phase interval that the frequency expansion sequence that receiver receives is spoken between the local frequency expansion sequence is bigger usually, and it is longer to search for these required times fully, therefore, how to obtain fast and effectively synchronously, be a key index of system.Therefore, the main performance index of catching is capture time and acquisition probability, and its performance will influence power system capacity.
Any one frequency expansion sequence grabber, its taproot unit all is a detector, whether accurately this detector can be relevant or noncoherent (demodulation carrier wave).Detector adopts the correlation intergal device to realize usually, and the correlation intergal device can adopt passive integrator (as matched filter) or active correlation intergal device (removing correlator as integration) to realize again.Output result to detector can adopt different decision rule (as Bayes (Bayes) criterion, Newman-Pearson (Neyman-Pearson) criterions etc.) judge whether the frequency expansion sequence grabber has captured correct phase point, different decision rule has determined to be used as in the frequency expansion sequence grabber whether the choosing of threshold value of acquisition success of judgement frequency expansion sequence.Each used time of detection of detector can be that fix or variable in the frequency expansion sequence grabber.Further say, after detecting for the first time, can also verify that checking is in order to strengthen original synchronous hypothesis, to reduce contingent false alarm probability.Usually we call single to the catching method that does not have verifying logic and stay method, and the catching method that one or more verifying logics are arranged is called the method for repeatedly staying.The single method of staying can adopt the complete period to be correlated with or the partial periodicity correlation technique detects, and this is relevant with concrete frequency expansion sequence length and system complexity.Repeatedly stay method almost without any exception in detecting for the first time shorter partial periodicity of employing time relevant, to accelerate acquisition procedure, because the relevant high shortcoming of false alarm probability of partial periodicity can be improved by verifying logic.
Another one importance in the frequency expansion sequence grabber is exactly the search strategy to the unknown phase interval, i.e. the process in all unknown phase intervals between the specific search sending and receiving frequency expansion sequence of detector employing.This traversal search process can be continuous or discrete.Usually we are divided into limited junior unit to all unknown phase intervals, detect a unit at every turn.Search plan can be serial successively, also can be parallel, perhaps and go here and there combination, perhaps from certain specific zone, expands to whole zone gradually.
Existing frequency expansion sequence catching method mainly adopts the active correlation intergal catching method or the matching wave filter capture method of serial search, parallel search, memory parallel search and hybrid parallel search fully.Serial search correlation intergal catching method is that the frequency expansion sequence that receives is carried out one by one phase search, and till frequency expansion sequence phase place that receives and local frequency expansion sequence Phase synchronization, though the method is simple, capture time is but very long.Fully parallel search correlation intergal catching method and matching wave filter capture method are maximum quick capturing methods of usefulness up to now, and their capture time is short, but realizes circuit complexity (needed hardware resource is many).Memory parallel search correlation intergal and hybrid parallel search correlation intergal catching method also are the methods of catching fast, they combine the advantage of serial search correlation intergal and complete parallel search correlation intergal catching method, made a balance and select between hardware resource and systematic function.Above-mentioned several catching method has plenty of to be realized simply, but capture time is long.It is short to have plenty of capture time, need expend a large amount of hardware resources but implement.
Purpose of the present invention is exactly at above-mentioned the deficiencies in the prior art, reverse random access channel is caught fast in a kind of WCDMA of being applicable to communication system new method and device are proposed, and the additional result analysis, can reach and can either save hardware resource, can realize the purpose of catching fast again.
In the WCDMA communication system, the channel architecture of reverse random access channel as shown in Figure 1.Among the figure, prefix part is produced after through the scrambler spread spectrum by prefix signature, and the prefix signature is to be to obtain after the long Kazakhstan moral sign indicating number sequence of 16 chips repeats 256 times by length, and the total length of prefix signature just is that 4096 chips are long, and prefix is signed and always had 16.Prefix part adopts Quadrature Phase Shift Keying (QPSK) band spectrum modulation.Have only 4096 chips long because prefix inserts the length of part, receiving terminal must will utilize the long prefix of 4096 chips at an access slot, and promptly 5120 chip lengths search correct phase point in the time.
(3) summary of the invention:
The quick capturing method of reverse random access channel of the present invention, the prefix signature of described Random Access Channel is to be formed for 256 times by the long Kazakhstan moral sign indicating number sequence extension of 16 chips, it is characterized in that after the baseband signal that receives is passed through I, the demodulation of Q scrambler respectively, carry out the long quick Kazakhstan moral code conversion of 16 chips respectively, obtain 16 correlated results respectively to the prefix signature, each correlated results is carried out 256 times add up, each accumulated value that obtains is carried out square.I, Q two-way respectively obtain 16 square values, with the corresponding addition of I, Q two-way 16 square values separately, obtain 16 judgement data, choose maximum wherein, compare with first and second threshold value of setting, when described maximum during all greater than two threshold values, show that grabber has captured correct phase point and correct prefix signature, system enters tracking mode.
The inventive method step can be described below:
1. the data that receive at first are buffered in the data register, read the long data of 16 chips at every turn and give the scrambler demodulation.
2. the I road and the Q roadbed band signal data that receive are removed scrambler processing (scrambler demodulation), exactly with local spectrum-spreading code generator scrambler that produces and the relevant treatment that receives 4096 chip lengths of signal work.
3. scrambler demodulated I, Q two paths of data are carried out 16 long quick Kazakhstan moral code conversions (FHT) respectively, breathe out the relevant of moral sign indicating number sequence with quick realization.I behind the FHT, Q two-way result are carried out respectively square, and last, the results added with after I, Q two-way square obtains detecting court verdict.The concrete operations of 16 long Kazakhstan moral code conversions as shown in Figure 2.Among the figure 1,2 ... 16 expression length are the 1st of 16 Kazakhstan moral sign indicating number sequence, the 2nd ... the 16th.
4. the court verdict that obtains after the incoherent detection carries out maximum and chooses, and this is because length is the quick Kazakhstan moral code conversion of 16 chips, and just in time corresponding 16 correlations of input signal with 16 prefix signatures need therefrom select of maximum.
5. for reducing the false alarm probability of grabber, thereby shorten capture time, the present invention has adopted the double threshold of the band back checking method of determining.Being about to the court verdict that step 4 obtains at first compares with threshold value 1, do like this that can to exclude be not correct phase point obviously, if court verdict greater than threshold value 1, then compares this value again with threshold value 2, like this, can obtain higher detection probability and lower false alarm probability.Grabber is adjudicated the whether setting of the required threshold value of acquisition success and is adopted Newman-Pearson (Neyman-Pearson) criterion.
6. if the court verdict of detector output is greater than threshold value, system enters tracking mode, otherwise grabber changes the phase state of local scrambling generator, and repeating step 1-6 is to proceed detection to next unknown phase state.
The quick catching device of reverse random access channel of the present invention, it is characterized in that: this device comprises data register, the scrambler demodulator, breathe out moral code converter (FHT), accumulator, squarer, adder, maximum-value selector, first comparator and second comparator, validator and phase search controller, wherein data register is with I, the Q two-way receives data and carries out buffer memory, read 16 chip long datas carries out the scrambler demodulation for the scrambler demodulator at every turn, breathing out the data of moral code converter after to the scrambler demodulation carries out the long quick Kazakhstan moral code conversion of 16 chips and realizes breathing out the relevant of moral sign indicating number sequence, accumulator to conversion after data carry out 256 times and add up, squarer carries out square, data are carried out addition by adder after square, so far obtain 16 court verdicts, maximum-value selector is selected maximum again, this maximum enters first comparator and first thresholding compares, if just enter validator greater than first thresholding, enter second comparator and second thresholding more relatively, if greater than second thresholding then illustrate and catch the correct phase point, system enters tracking mode, otherwise continues search by the phase search controller.
The invention provides in the WCDMA system quick capturing method and device based on the reverse random access channel of quick Kazakhstan moral code conversion, it has effectively utilized the characteristics of reverse random access channel among the WCDMA, by adopting the moral code conversion of quick Kazakhstan to replace traditional active correlation intergal device, can shorten the correlation intergal time greatly, realize catching fast; Simultaneously, adopt and breathe out the traditional correlation intergal device of moral code conversion replacement, can also save the needed hardware resources of acquisition equipment in a large number.The needed hardware resource of the inventive method and existing catching method is compared as follows:
We suppose that the unknown phase state range that grabber need be searched for is 200 chips, if search precision is 1/2 chip, then having 400 unknown phase points needs search.
If adopt the catching method of existing serial phase search correlation intergal, can not satisfy the WCDMA system to of the requirement (seeing accompanying drawing 4) of mean acquisition time needs less than 5120 chip lengths times.
If adopt the quick capturing method of parallel fully phase search correlation intergal, then, need 400*16*2=12800 parallel correlator for 400 unknown phase points.
If adopt the quick capturing method of traditional hybrid parallel phase search correlation intergal, suppose that correlation length gets 1024 chips, the prefix part of 4096 chip lengths can be divided into 4 serial related intervals altogether so.The search of 400/4=100 unknown phase point must be finished in each interval.Simultaneously, because 16 prefixes signature is arranged, and I, Q two-way walk abreast, so the number of the parallel correlator that needs is 100*16*2=3200 altogether.
If use matched filter to realize, need there be two groups of 16 different matched filters to realize matched filterings simultaneously to I, Q two paths of data signal and 16 prefix signatures to the catching of reverse random access channel among the WCDMA.And in fact digital matched filter is exactly a multistage parallel accumulator, and the number of accumulator is corresponding with the correlation length of detector, long if correlation length is got 1024 chips, and a matched filter just needs 1023 accumulators to realize so.Just need 1023*2*16 accumulator altogether.
Beneficial effect of the present invention: adopt the inventive method, breathe out moral code conversion realization to breathing out the related operation of moral sign indicating number sequence, not only save correlation time, can also finish being correlated with simultaneously to 16 prefix signatures with quick.Because the Kazakhstan moral sign indicating number sequence of reverse random access channel prefix is that 16 chips are long among the WCDMA, like this, only need 4 grades of conversion just can finish the relevant of the long Kazakhstan moral sign indicating number sequence of 16 chips.Because every grade of conversion needs 8 accumulators, then whole conversion only needs 32 accumulators just passable.To 16 available signatures and two branch roads of I, Q, need 32*16*2=1024 accumulator and 2 Kazakhstan moral transcoders (corresponding to I, Q two-way) just passable altogether, to compare with above-mentioned quick capturing method, required hardware resource has reduced greatly.
(4) description of drawings:
Fig. 1 is the channel architecture of uplink random access channel in the WCDMA system;
Fig. 2 is for to catch theory diagram fast based on the reverse random access channel of quick Kazakhstan moral code conversion;
Fig. 3 is for to catch the realization block diagram fast based on the reverse random access channel of quick Kazakhstan moral code conversion;
Fig. 4 is the detection probability performance map;
Fig. 5 is the false alarm probability performance map;
Fig. 6 is mean acquisition time figure;
(5) preferred forms:
Further specify the present invention below in conjunction with drawings and Examples.
Fig. 3 is the realization block diagram of WCDMA reverse random access channel quick capturing method of the present invention and device.
Apparatus of the present invention comprise with lower module: module 101,103 is respectively I, Q two paths of data register.The data that receive at first are buffered in the data register, read the long data of 16 chips at every turn, give the scrambler demodulation module, and promptly the scrambler demodulator 102,104.The I road and the Q roadbed band signal data that receive are carried out the scrambler demodulation; Module 105 and 106 is respectively I road and the Q road scrambling generator that is used for the scrambler demodulation.Module 107 and 108 is used for scrambler demodulated I, Q two paths of data, carrying out length respectively is the quick Kazakhstan moral code conversion (FHT) of 16 chips, the FHT module is exactly to replace traditional correlator with breathing out the moral code conversion, realization is to breathing out the relevant of moral sign indicating number sequence, compare with traditional correlation technique, adopt and breathe out the moral code conversion fast, can not only shorten correlation time, and can also obtain all 16 correlations (corresponding 16 prefixes signature) of breathing out moral sign indicating number sequence simultaneously.
Module 109-124 is that accumulator is that 16 I circuit-switched data (respectively corresponding 16 prefixes signature) behind the FHT is carried out respectively adding up for 256 times, and 125-140 module (accumulator) is to 16 Q circuit-switched data (corresponding respectively 16 prefixes signature) behind the FHT carry out respectively adding up for 256 times (in order to obtain and the corresponding spread processing gain of accumulation length); The module that I after adding up, Q two paths of data (16 prefixes signatures are arranged respectively) are carried out square is 141-172 (squarer); To square after I, Q two paths of data (16 prefixes signatures the are arranged respectively) module of carrying out addition be 173-188 (adder); Arrive this, WCDMA reverse random access channel of the present invention is caught fast and is adorned the incoherent detection that has realized I, Q two paths of signals, has obtained 16 court verdicts (corresponding 16 prefixes signature); Module 189 (maximum-value selector) is used for 16 statistical decision results are selected, and selects maximum; This value is compared in comparator 1 module 190 with thresholding 1 earlier, if greater than thresholding 1, testing result is just delivered to authentication module 191 (validator), compare in comparator module 192 with thresholding 2 again, if greater than thresholding 2, then correct phase point and the employed prefix signature of current mobile station have been caught in explanation, and system just enters tracking mode.Otherwise acquisition equipment continues the next unknown phase point of search under phase search controller module 193 (phase search controller) control.
The hardware resource of the inventive method and above-mentioned other several quick capturing methods more as mentioned above, their performances under the same conditions are more respectively as Fig. 4, shown in 5,6.
Claims (2)
1. the quick capturing method of a reverse random access channel, the prefix signature of described Random Access Channel is to be formed for 256 times by the long Kazakhstan moral sign indicating number sequence extension of 16 chips, it is characterized in that the baseband signal that receives is being passed through I respectively, after the demodulation of Q scrambler, carry out the long quick Kazakhstan moral code conversion of 16 chips respectively, obtain 16 correlated results respectively to the prefix signature, each correlated results is carried out 256 times to add up, each accumulated value that obtains is carried out square, I, the Q two-way respectively obtains 16 square values, with I, the corresponding addition of Q two-way 16 square values separately, obtain 16 judgement data, choose maximum wherein, compare with first and second threshold value of setting, when described maximum during all greater than two threshold values, show that grabber has captured correct phase point and correct prefix signature, system enters tracking mode.
2. the quick catching device of a reverse random access channel, it is characterized in that: this device comprises data register, the scrambler demodulator, breathe out moral code converter (FHT), accumulator, squarer, adder, maximum-value selector, first comparator and second comparator, validator and phase search controller, wherein data register is with I, the Q two-way receives data and carries out buffer memory, read 16 chip long datas carries out the scrambler demodulation for the scrambler demodulator at every turn, breathing out the data of moral code converter after to the scrambler demodulation carries out the long quick Kazakhstan moral code conversion of 16 chips and realizes breathing out the relevant of moral sign indicating number sequence, accumulator to conversion after data carry out 256 times and add up, squarer carries out square, data are carried out addition by adder after square, so far obtain 16 court verdicts, maximum-value selector is selected maximum again, this maximum enters first comparator and first thresholding compares, if just enter validator greater than first thresholding, enter second comparator and second thresholding more relatively, if greater than second thresholding then illustrate and catch the correct phase point, system enters tracking mode, otherwise continues search by the phase search controller.
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| CNB021165033A CN1163008C (en) | 2002-03-27 | 2002-03-27 | Fast capture method and device for reverse random access channel |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN100393168C (en) * | 2004-08-04 | 2008-06-04 | 中兴通讯股份有限公司 | CDMA system random access threshold multi-path selection method |
| CN100387096C (en) * | 2004-12-23 | 2008-05-07 | 华为技术有限公司 | Method for determining capture threshold of random access channel through physical layer |
| CN101128004B (en) * | 2006-08-18 | 2010-10-27 | 华为技术有限公司 | Detection method, terminal and network device for random access |
| CN101166362B (en) * | 2006-10-20 | 2011-03-16 | 华为技术有限公司 | Method and equipment for originating and detecting reverse access |
| CN101217817B (en) * | 2008-01-09 | 2010-09-15 | 华为技术有限公司 | Channel searching device, method and system |
| CN101741785B (en) * | 2009-12-21 | 2012-12-19 | 中兴通讯股份有限公司 | Methods and system for recognizing random access pulse signals |
| CN111565161B (en) * | 2020-04-28 | 2022-05-27 | 北京升哲科技有限公司 | Baseband transmitter, baseband receiver, modulation and demodulation system and terminal |
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