CN1059998C - Multi-stage iteration multi-subscriber test method - Google Patents
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Abstract
The present invention provides a multilevel iteration multiuser detection method applied to a CDMA communication system. The detection method of the present invention has the steps that an external connection signal r(t) is converted into an output signal 'y' through a matched filter bank (1), the signal 'y' is sent into a multilevel iteration multiuser signal processing module B(2), the output is Dy through the primary iteration, the output is D<2>y through the secondary iteration, the output is D<n>y through the nth iteration, and finally, the output are sent into an accumulator for judgment to obtain treatment results b. When adopted, the method of the present invention obviously improves the capacity of the DS/CDMA communication system, eliminates the multi-access interference between users, improves the near-far effect of the system, and has the advantage of easy hardware real-time implementation.
Description
The present invention is the method that the multi-stage iteration multi-subscriber in a kind of DS/CDMA of being applied to communication system detects, and belongs to the multi-access interference suppression technical field in the DS/CDMA communication technology.
The cdma communication technology will occupy absolute advantage in the development of Communication Technique of making rapid progress.Yet a deficiency the most significant of CD-MA communication system is exactly the multiple access interference between the user.Therefore, great amount of manpower and material resources have been dropped in countries in the world on the multi-access interference suppression Study on Technology.
The multi-access interference suppression Study on Technology has had the history of more than ten years in the world, and the method for many in theory Multiuser Detection is suggested.In moving towards practical application, these detection methods all exist some shortcomings that make whole system be difficult to accept, particularly real-time requirement.Therefore (, IS-665) also do not adopt multiuser detection as yet in the existing C DMA communication system as IS-95.In recent years, how take up research in the world pushes multiuser detection to use to.Wherein do to such an extent that be preferably the polynomial expansion detector that the S.Moshavi of U.S. Bellcore communication experiment chamber finds out, his this detector arrangement is simple, and there are not the data delay and the edge effect of traditional linear detector (decorrelation and MMSE), can realize easily with hardware, and can the adaptive system requirement of processing in real time.We find that under study for action there are following three shortcomings in the multinomial detector of Moshavi: the progression of (1) needs is many; (2) need to estimate in advance several parameters (with progression as many), the acquisition of these parameters needs a large amount of complicated calculations and emulation; (3) system has the user to increase and when reducing, parameter is wanted corresponding change.Therefore, need storage in large quantities to estimate good parameter in advance.
The purpose of this invention is to provide a kind of multi-stage iteration multi-subscriber test method that can eliminate the interference of the multiple access between the user in the cdma communication system.
Multi-stage iteration multi-subscriber test method of the present invention be with outer signal r (t) through matched filter banks output signal " y ", " y " sends into the multi-stage iteration multi-subscriber signal processing module with signal, is output as Dy through first order iteration, second level iteration is output as D
2Y, n level iteration is output as D
nY, sending into accumulator at last adjudicates and obtains result, be the unit that the output signal " Y " of matched filter banks is sent to " α R " module in the multi-stage iteration multi-subscriber signal processing module, " α R " is made of one-level spread spectrum and despread unit, the output signal Y of matched filter
kBy the used spreading code S of user
k(t-τ
k) spread spectrum once more, carry out the chip addition according to their the time delay delay of nature then, to on each chip and multiply by a constant alpha of appointing in advance, then the data of a spreading rate obtaining are like this carried out matched filtering with separately spreading code again, obtain the output of module α R, each user's of this module the output and the output result of its corresponding matched filtering are subtracted each other, it is the output addition of matched filter that difference is delivered in this user's the judgement accumulator with existing amount, through some grades handle with upper type, amount in the judgement accumulator is adjudicated, promptly obtain end product b.
Every grade of iteration D is by a spread spectrum and despread unit α R and a vectorial delay cell T
bAnd adder A constitutes spread spectrum and despread unit α R and vectorial delay cell T
bOutput be the input of every grade of iteration D, spread spectrum and despread unit α R and vectorial delay cell T
bOutput termination adder A, the output of adder A is the output of every grade of iteration D.
The following describes this structure and remove the principle that multiple access disturbs: for the convenience on the mark, we are example with the synchronization CDMA situation.When asynchronous, in the vector signal stream each user's signal component stream have in time one relative time delay structure, all have same structure in relative time delay owing to have the input and output signal stream of the α R module of parallel processing structure, so this detection architecture is to asynchronous same can work.In the time of synchronously, we are as long as the length of putative signal stream is l.Notice that α R module defined above is α Rz to the output of input vector signal flow Z, the R here is actually a correlation matrix, and order of matrix number and number of users equate.Therefore if to D signal processing module input signal stream z, then it is output as Dz=z-α Rz=(I-α R) z, and I is a unit matrix here.Therefore
W=y+Dy+ ... + D " y=[I+ (I-α R)+(I-α R)
2+ ... + (I-α R)
n] launch by matrix
(α R)
-1=I+ (I-α R)+(I-α R)
2+ ... + (I-α R)
n+ ... know as long as in the interval
In get constant alpha, ρ is the spectral radius of matrix R, just can so that the spectral radius of matrix I-α R less than 1, thereby make the convergence of above-mentioned series expansion.As long as therefore get finite term, (α R) just arranged
-1≈ I+ (I-α R)+(I-α R)
2+ ... + (I-α R)
nThereby,
(R
-1Y).Therefore, we know that above-mentioned detector is actually the multi-stage iteration realization that decorrelation detects, and progression is many more, and its performance is more near decorrelation detector.As everyone knows, decorrelation detects the characteristic with the multiple access interference that suppresses between the user, conciliates the inhibit feature that the much the same multiple access of coherent detection disturbs thereby the method and structure that the present invention proposes has.The thought of Multiuser Detection is to utilize all users' spreading code, information such as amplitude, position phase, timing.Angle with integral body is carried out signal processing, eliminate the purpose that multiple access disturbs thereby reach, its basic ideas are to add a multiple user signals processing module in the matched filter banks back, this module is handled the output of matched filter banks, its output has been eliminated the multiple access interference fully, its operation principle and the course of work are: the output of matched filter banks represents that with vectorial y y imports " multiple user signals processing module ", and the output of this module promptly gets end product through judgement.And " multiple user signals processing module " be made of some levels, and concrete progression decide on used spreading code of user and spreading gain, and each grade is made up of " D " module.In the first order, " D " module is handled its input y, obtains new vectorial Dy, and Dy sends into vectorial accumulator and y adduction storage mutually, and Dy is admitted to second " D " module simultaneously, obtains partial output D
2Y, D
2Y sends into the vectorial y+Dy adduction storage mutually of vectorial accumulator and the inside, D simultaneously
2Y is admitted to the 3rd module, continues to establish and passed through the M level through the processing identical with the first order or the second level, and then the storage vector of accumulator the inside is (I+D+ ... + D
M) y.At last in this accumulator and vector adjudicate, promptly get last judgement vector .Wherein each " D " module is by a vectorial delay cell " T
bWith a α R " the composing in parallel of module.
This invents the base station receiver of available DS/CDMA communication system, and the phase mutual interference of its effect between can the cancellation different user obtains better receptivity, thereby improve the message capacity and the communication quality of whole system.The main following points of its advantage:
1. can significantly improve the DS/CDMA capability of communication system.Because the multiple access of having eliminated between the user disturbs, can be so that the number of users that system can hold has significant increase.Studies show that, in each sub-district of a mobile DS/CDMA communication system, use this multi-user detector after, the number of users that the sub-district is held increases original more than one times;
2. can improve the anti-near-far interference of system, the reduction system is to the requirement of power control.When certain user's power increases (walking out as mobile phone) suddenly in elevator, power control system has little time reaction again, and this user will produce strong interference to other user, makes that other user can't operate as normal; In addition, when certain user's power reduces (as entering elevator) suddenly, because other user's interference, this user's signal can't normally be detected, therefore with regard to cisco unity malfunction.This detector can effectively suppress both of these case;
This detector to system without any additional requirement.As long as existing traditional detection energy operate as normal, this detector is the energy operate as normal just;
4. be easy to the hardware real-time implementation.Because this detector only contains spread spectrum and despread unit, that therefore can have no difficulty uses the ASIC real-time implementation.This is a remarkable advantage of this detector;
5. detect performance and be equivalent to that decorrelation detects and MMSE detects, but overcome the shortcoming that the edge effect that exists in the present treating method and data stop over;
6. compare with the multinomial detector that the Moshavi of U.S. Bellcore company proposes, have its all advantages, and overcome its wretched insufficiency---need to carry out a large amount of emulation, estimate very many parameters in advance according to the employed spreading code of user.Here, we only need estimate a parameter easily.
Fig. 1 is the vector structure schematic diagram of multi-stage iteration multi-subscriber test method of the present invention.Input signal r (t) is wherein arranged, matched filter banks 1, multi-stage iteration multi-subscriber signal processing module B2, output signal .This figure only illustrates the secondary iterative processing.
Fig. 2 is a structure principle chart of the present invention, only shows 1 grade among the figure.
Fig. 3 is the whole system module connection diagram of making the multi-stage iteration multi-subscriber detector.
Embodiment of the present invention are as follows:
Its signal processing method is: at first external input signal r (t) is sent into matched filter banks 1, signal through matched filter banks output is y, then signal y is sent into multi-stage iteration multi-subscriber signal processing module 2, in this module, every grade of iteration D is by a spread spectrum and despread unit α R and a vectorial delay cell T
bAdder A constitute spread spectrum and despread unit α R and vectorial delay cell T
bWith input be the input of every grade of iteration, promptly signal y at first sends into this end, spread spectrum and despread unit α R and vectorial delay cell T
bOutput termination adder A, the output of adder A is the output of every grade of iteration D, is output as Dy through first order iteration, iteration is output as D through the second level
2Y is output as D through n level iteration
nY sends into accumulator at last and adjudicates and obtain result .
The embodiment that realizes the application specific processor of above processing method have multiple simply introduce a kind of way of utilizing general digital signal processing (DSP) chip to realize this multi-user detector here.Concrete performing step is as follows:
The first step: the dsp chip of selecting to be suitable for realizing this multi-user detector.Here the TMS320C50 chip that select U.S. Ti company to produce.
Second step: purchase the TMS320C50 chip of Ti company and the developing instrument on the supporting PC thereof.Its detailed explanation of the TMS320C50 chip of purchasing can be referring to the interrelated data of any TMS320C50 that provides about Ti company.
The 3rd step: utilize the development environment on the PC of purchasing, write corresponding assembler.The spreading gain of our supposing the system is 64, three users is arranged in work.The connection of whole system module is as shown in Figure 3: suppose that the TMS320C50 chip is connected by control bus, address bus, data/address bus with " A/D " analog to digital converter, three users' PN code generator and decoder, concrete handling process is as follows:
1. finished the sampling of 64 chip data when " A/D " analog to digital converter, the notice that sends instructions TMS320C50 chip reads this 64 data, and data is delivered to the data-interface of TMS320C50;
2.TMS320C50 obtain read data instruction, data read in appointed its memory;
3. three PN code generators are finished chip synchronization, and 64 PN code datas of each self-generating send instructions successively and notify TMS320C50 chip reading of data, and data are delivered to the data-interface of TMS320C50;
4.TMS320C50 obtain the read data instruction, three users' PN sign indicating number read in the memory of appointment;
5.TMS320C50 by the Multiuser Detection principle that provides here, the data in the memory are handled, are obtained three users' bit decision result;
Notify the decoder read data 6.TMS320C50 send instructions, and data are delivered to the data-interface of decoder;
7. decoder is read away data;
8. repeat the step of 1-7, intact up to the data processing that all antennas receive.
Top flow process is the flow process of whole system work, is write the instruction that TMS320C50 need carry out as corresponding assembler.The 5th step write as a subprogram, and this subprogram is write by the theory diagram of multi-user detector just.
The 4th step: utilize the assembler in the TMS320C50 developing instrument, the assembler of finishing is generated the COFF file destination;
The 5th step: utilize the linker in the TMS320C50 developing instrument, the COFF file destination is converted into executable coff file;
The 6th step: utilize the simulator (simulator) in the TMS320C50 developing instrument, artificial debugging can be carried out coff file;
The 7th step: utilize the hexadecimal crossover tool (hex conversionutility) in the TMS320C50 developing instrument, can carry out coff file and be converted into the hexadecimal file destination;
The 8th step: utilize among the EPROM of burned device with the burned TMS320C50 of hexadecimal file destination.
Like this, we have just obtained a TMS320C50 chip that the Multiuser Detection scheme that we are proposed is solidified.The good element of pertinent regulations in this chip and " the 3rd step " described system is connected, and this chip is the energy operate as normal just, receives principle by the multi-user that we proposed and finishes the function that the multi-user receives.
Claims (1)
1. multi-stage iteration multi-subscriber test method, it is characterized in that this detection method is through matched filter banks (1) output signal " y " with outer signal r (t), signal " y " is sent into multi-stage iteration multi-subscriber signal processing module (2), be output as Dy through first order iteration, second level iteration is output as D
2Y, n level iteration is output as D
nY, sending into accumulator at last adjudicates and obtains result, it is the unit that the output signal " Y " of matched filter banks (1) is sent to " α R " module in the multi-stage iteration multi-subscriber signal processing module (2), " α R " is made of one-level spread spectrum and despread unit, the output signal Y of matched filter (1)
kBy the used spreading code S of user
k(t-τ
k) spread spectrum once more, carry out the chip addition according to their the time delay delay of nature then, to on each chip and multiply by a constant alpha of appointing in advance, then the data of a spreading rate obtaining are like this carried out matched filtering with separately spreading code again, obtain the output of module α R, each user's of this module the output and the output result of its corresponding matched filtering are subtracted each other, it is the output addition of matched filter that difference is delivered in this user's the judgement accumulator with existing amount, through some grades handle with upper type, amount in the judgement accumulator is adjudicated, promptly obtain end product b.
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|---|---|---|---|
| CN98111378A CN1059998C (en) | 1998-06-22 | 1998-06-22 | Multi-stage iteration multi-subscriber test method |
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|---|---|---|---|
| CN98111378A CN1059998C (en) | 1998-06-22 | 1998-06-22 | Multi-stage iteration multi-subscriber test method |
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| CN1059998C true CN1059998C (en) | 2000-12-27 |
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| US7684525B2 (en) * | 2002-01-09 | 2010-03-23 | Nokia Corporation | Method and receiver for reception of a composite signal |
| CN100338932C (en) * | 2002-12-06 | 2007-09-19 | 冯志强 | Signal processor for suppressing multiuser interference in DS-CDMA system |
| CN104301267B (en) * | 2014-11-11 | 2017-07-04 | 山东大学 | The multistage iteration detection method and device of a kind of mimo wireless communication receiver |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0641102A2 (en) * | 1993-08-24 | 1995-03-01 | Philips Electronics Uk Limited | Direct sequence - Code division multiple access receiver with multiuser interference canceller |
| WO1998010537A1 (en) * | 1996-09-04 | 1998-03-12 | Ericsson Inc. | Combined subtractive interference cancellation and space diversity signal processing in a cellular cdma communications system |
| US5757791A (en) * | 1996-04-18 | 1998-05-26 | American Wireless Technology, Inc. | Multistage linear receiver for DS-CDMA systems |
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1998
- 1998-06-22 CN CN98111378A patent/CN1059998C/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0641102A2 (en) * | 1993-08-24 | 1995-03-01 | Philips Electronics Uk Limited | Direct sequence - Code division multiple access receiver with multiuser interference canceller |
| US5757791A (en) * | 1996-04-18 | 1998-05-26 | American Wireless Technology, Inc. | Multistage linear receiver for DS-CDMA systems |
| WO1998010537A1 (en) * | 1996-09-04 | 1998-03-12 | Ericsson Inc. | Combined subtractive interference cancellation and space diversity signal processing in a cellular cdma communications system |
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