CN101521536A - Mobile station receiving circuit for CDMA system sparetime spread spectrum method - Google Patents

Abstract

The invention relates to a mobile station receiving circuit for a CDMA system sparetime spread spectrum method, which comprises two matching wave filters in parallel connection, two multipliers, two adders and two decision devices, wherein the two matching wave filters input receiving signals respectively; the two multipliers are connected with the two matching wave filters respectively; the two multipliers are connected with the two adders respectively; the two decision devices are connected with the two adders respectively; and the input of each adder is an opposite phase of the output of one multiplier and the output of the other multiplier. With the invention, a mobile station obtains diversity gain when receiving data, the information transmission quality of a system is improved, and the design of the receiving circuit is simplified.

Description

The mobile station receiving circuit of cdma system space-time spectrum extending method

Technical field

The present invention relates to the mobile station receiving circuit of cdma system space-time spectrum extending method, belong to moving communicating field.

Background technology

The direct spread spectrum technology of multiple transmit antennas is used for the forward direction and the reverse link of cdma system, can effectively improve systematic function.CDMA 1X adopts the Direct-Spread transmit diversity techniques, and it has dual mode:

(1) a kind of is Orthogonal Transmit Diversity mode OTD (Orthogonal TransmitDiversity)

Method is that cdma base station elder generation separate data streams is carried out spread spectrum with different quadrature Walsh sign indicating numbers to two data streams again, and passes through two transmission antennas transmit of base station.

(2) another kind is space-time spectrum extending diversity mode STS (Space Time Spreading)

The data that two separate antenna emissions of cdma base station usage space have interweaved are used identical original Walsh sign indicating number channel, and odd data stream and even data stream jointly rather than are dividually launched by two antennas.

Use the forward link transmit diversity techniques can reduce transmitting power, anti-Rayleigh fading increases power system capacity.

The complete space diversity (OTD) of cdma base station though available two transmitting antennas realize, be that the bandwidth with twice is that cost obtains, each user needs with the bandwidth spread spectrum coding that has more a times.The bandwidth resources that increase have limited the whole efficiency of cdma system.

In addition, in direct spread spectrum othogonal emitting diversity technology (OTD), do not utilize the space diversity characteristic of channel fully.When travelling carriage sinks into deep fade in slow fading channel, the advantage of diversity all will disappear any time.Since the wireless data users of many 3rd generations communication be static or translational speed (walking) very slow, reduce dependence to the time varying channel parameter, the importance of space diversity highlights.At Hochwald B, Marzetta T L, the document that Papadias C B collaborates: the space-time spectrum extending emission diversity scheme (ATransmitter Diversity Scheme for Wideband CDMA Systems Based onSpace-Time Spreading) that is used for wideband CDMA system has been done detailed explanation to this.

In the existing space-time spectrum extending technology (STS), the spacing of base station transmit antennas must could guarantee that transmitting of each unit of antenna array is uncorrelated mutually greater than 10-15 times of radiofrequency signal wavelength, and this causes difficulty in Project Realization.Because because objective condition, the spacing of cdma base station transmitting antenna possibly can't satisfy aforementioned requirement.The space-time spectrum extending specification requirement travelling carriage of existing multiple transmit antennas needs many antennas, and this realizes bringing great difficulty for the technology of travelling carriage, has increased the travelling carriage cost, has also increased the travelling carriage volume.Travelling carriage in the aforementioned documents receives the despreading algorithm need carry out a large amount of matrix operations, thereby is difficult to realize.

The present invention eliminates multiple access in the situation of multi-user multi-path and disturbs, and improves the error rate of system performance.

Summary of the invention

The present invention proposes the mobile station receiving circuit of using the cdma system space-time spectrum extending method.Travelling carriage of the present invention is with an omnidirectional antenna, and two-way matched filtering reduction odd and even data stream is realized space-time spectrum extending method of the present invention, reduces the travelling carriage volume and has saved cost.

Travelling carriage of the present invention does not need to carry out complicated matrix operation, can directly odd and even data stream be merged and adjudicate, and circuit design is simple.

Use in the mobile station receiving circuit of the present invention to postpone spread spectrum series C1 and C2 despreading and channel parameter h1 and h2 weighting, the multiple access that can suppress under multi-user's situation inserts interference MAI (multiple access interference).

The embodiment of the mobile station receiving circuit of application cdma system space-time spectrum extending method of the present invention is: the receiving circuit of travelling carriage comprises two and the matched filter that connects, import received signal respectively, two multipliers are connected with two matched filters respectively, two adders are connected with multiplier respectively, and the decision device that is connected with two adders respectively, wherein the input of each adder is output anti-phase of the output of a multiplier and another multiplier.

The present invention proposes the cdma system space-time spectrum extending method, can realize complete diversity under the situation of no extra bandwidth resource, each user only needs a spread-spectrum codes, is easy to realize.The implementation of cdma system space-time spectrum extending method of the present invention is:

A kind of cdma system space-time spectrum extending method, this cdma system comprises the travelling carriage of at least one base station and a plurality of and base station communication, it is characterized in that,

The base station is transmitted according to following steps:

1) each user's data stream is divided into odd data stream and even data stream

2) odd data stream and even data flow point are not carried out spread spectrum, obtain signal behind the spread spectrum

3) with signal plus behind the spread spectrum, t1, t2 obtain transmitting

4) by two antennas transmit respectively t1, t2;

Travelling carriage obtains restoring data according to following steps:

5) receiving circuit of travelling carriage divides the two-way despreading to received signal, obtains after first despreading signal behind the signal and second despreading

6) receiving circuit of travelling carriage to first and second despreadings after signal carry out the channel parameter weighting, obtain the combined signal of signal after first and second despreadings

7) receiving circuit of travelling carriage with first and second despreadings after the combined signal of signal adjudicate respectively, obtain restoring data then.

Described cdma system space-time spectrum extending method is characterized in that step 2) in odd data stream and even data are flowed usefulness spread-spectrum codes c1 and c2 be mutually orthogonal, $c_i^H{c}_j={\mathrm{\δ}}_{\mathrm{ij}}$ , " H " represents complex-conjugate transpose, and obtained by same spread-spectrum codes.

Described cdma system space-time spectrum extending method is characterized in that, spread-spectrum codes c1 and the c2 that odd data flows and even data stream spread spectrum uses obtained by spread-spectrum codes c0, and c0 is the Walsh sign indicating number sequence of finite length 64.

Described cdma system space-time spectrum extending method, it is characterized in that, step 1) and step 2) between also comprise step: the base station diversity circuit is adjusted the time difference between even data stream and the odd data stream, the time difference that the odd and even data when to make this time difference equal two transmitting antenna spacings be 10-15 times of radiofrequency signal wavelength flows.

Described cdma system space-time spectrum extending method is characterized in that, the method for the receiving circuit of travelling carriage judgement is in the step 7): the decision device of the receiving circuit of travelling carriage (341) to first despreading after signal merging with adjudicate Calculation Method and be:

If the real part of decision device (341) input signal then exports 1 greater than zero,

If decision device defeated (341) is gone into the real part of signal less than zero, then output-1,

The decision device of the receiving circuit of travelling carriage (342) to second despreading after signal merging with adjudicate Calculation Method and be:

If the real part of decision device (342) input signal then exports 1 greater than zero,

If the real part of decision device (342) input signal less than zero, then exports-1.

Described cdma system space-time spectrum extending method, it is characterized in that, further comprise in the step 7): the receiving circuit of travelling carriage to first despreading after the court verdict that closes of signal delay time, then with second despreading after the court verdict that merges of signal merge, obtain restoring data.

Described cdma system space-time spectrum extending method, it is characterized in that, step 6) comprises that the receiving circuit of travelling carriage estimates channel parameter h1, h2 that two antennas of cdma base station transmit, and respectively with first despreading after after signal d1 and second despreading signal d2 multiply each other, obtain d1h1 and d2h2; With the anti-phase addition of d1h1 and d2h2, adjudicate then, with the anti-phase addition of d2h2 and d1h1, adjudicate then.

In addition, the base station of the application cdma system space-time spectrum extending method that the present invention proposes, the wavelength that the spacing of its transmitting antenna needn't transmit greater than 10-15.Base station transmit antennas spacing of the present invention can be applicable to the engineering application more in 4 times of scopes to the wavelength that doubly transmits less than 10-15 greater than the wavelength that transmits.And the travelling carriage circuit design is simple, obtains the spread-spectrum codes of odd data stream and even data stream with a spread-spectrum codes.The radiating circuit of the base station of the application cdma system space-time spectrum extending method that the present invention proposes is: comprise two following decimation blocks, the time delay module that is connected with a following decimation blocks, a plurality of frequency multipliers that are connected with following decimation blocks or time delay module respectively and two adders that are connected with frequency multiplier, two following decimation blocks are sampled to two data flow with data flow, and wherein a data flow enters frequency multiplier after the time delay module time-delay.This time delay module is adjusted the time difference between two data flow, the time difference of two data flow when to make this time difference equal two transmitting antenna spacings be 10-15 times of radiofrequency signal wavelength.

Base station of the present invention only need be used two and be enjoyed a double blessing to antenna, and travelling carriage uses single omni.The base station adopts the present invention that multi-user's data flow is carried out transmit diversity in base band, and the single antenna travelling carriage adopts the present invention to receive data can obtain diversity gain, significantly improves the information transmission quality of wireless communication system on the whole.And the present invention can eliminate multiple access to a certain extent in the situation of multi-user multi-path and disturb, and improves the error rate of system performance.

Description of drawings

The present invention will be described in detail below by drawings and Examples.

Fig. 1 is base station diversity circuit figure of the present invention.

Fig. 2 is the flow chart of base station applies cdma system space-time spectrum extending method of the present invention among Fig. 1.

Fig. 3 is a mobile station receiver circuit diagram of the present invention.

Fig. 4 is the flow chart that travelling carriage is used cdma system space-time spectrum extending method of the present invention among Fig. 3.

Use the system of single transmit antenna base station when Fig. 5 is single user and use travelling carriage error rate comparative graph in the system of base station of the present invention.

Fig. 6 (a) and (b) use the system of the inventive method and do not use the error performance comparative graph of the system of the inventive method when being 4 and 16 users respectively.

Embodiment

With reference to Fig. 1, the present invention is the space-time spectrum extending method to the cdma system down link.System of the present invention comprises base station and a plurality of travelling carriage.There are two antennas the base station, and each travelling carriage has only an antenna.The base station is carried out transmit diversity to multi-user data stream b in base band, and its transmitting diversity circuit comprises decimation blocks 111 and 112, time delay module 122, frequency multiplier (multiplier) 131,132,133,134 and adder 141 and 142 down.

In conjunction with Fig. 2, the step of base station transmit signals Base-Band Processing is:

1) step 21: each user's data stream is divided into odd data stream and even data stream

Each user's data stream b is divided into two-way, and warp decimation blocks 111 and 112 down obtains odd data stream b1 and even data stream b2.Data flow b is the BPSK modulation.

2) step 22: adjust the time difference between even data stream and the odd data stream

Even data stream b2 adjusts its time difference between flowing with odd data at time delay module 122.The odd and even data stream time difference that time difference between the adjusted odd and even data stream equals two transmitting antenna spacings when being 10-15 times of radiofrequency signal wavelength, therefore use the present invention, two antenna distances on the base station do not require must be the radiofrequency signal wavelength 10-15 doubly, but change the time difference that odd and even data flows by time delay module 122, guarantee the irrelevance of travelling carriage received signal.Base station diversity circuit of the present invention provides time diversity by the time difference between time delay module 122 adjustment odd data streams and the even data stream.Two antennas of base station are very little to the multipath channel correlation of travelling carriage, can make the correlation of the delay spread-spectrum codes that delay spread-spectrum codes and its even data of single user's odd data stream flow very little.

If the spacing between two transmitting antennas of base station is greater than 10-15 times of the radiofrequency signal wavelength, at this moment, the delay value of time delay module is made as zero.In this case, the radiating circuit of base station of the present invention stands good.

3) step 23: odd data stream and even data flow point are not carried out spread spectrum, obtain signal behind the spread spectrum

The odd data stream of following decimation blocks 111 outputs mixes with spread-spectrum codes c1 at multiplier 131, obtains signal b1c1 behind the spread spectrum, mixes with spread-spectrum codes c2 at multiplier 134, obtains signal b1c2 behind the spread spectrum.

Here, spread-spectrum codes c1, c2 are that the length of quadrature is the spread-spectrum codes of 2P, are the real vectors of unit, and, $c_1^{\mathrm{<figure-callout\; id="2"\; label="H\; c"\; filenames="A200810188360E00181.png,A200810188360E00182.png"\; state="\{\{state\}\}">H</figure-callout>}}{c}_{}{}_2=0,$ " H " represents complex-conjugate transpose.

Calculate for convenient, among the present invention, spread-spectrum codes c1, c2 are calculated by one 64 Walsh sign indicating number sequence c0: c ₁=[c ₀c ₀] c ₂=[c ₀-c ₀]

Other one group of c1, c2 are c ₁=[c ₀0], c ₂=[0 c ₀].Adopt above-mentioned two groups of c1 and c2, owing to be to obtain by an identical Walsh sign indicating number sequence c0, so can not increase the existing spread spectrum yardage of system.Be appreciated that as long as satisfy $c_i^H{c}_j={\mathrm{\&delta;}}_{\mathrm{ij}}$ Quadrature spread-spectrum codes c1, the c2 of condition just can realize the present invention.

The even data of following decimation blocks 112 outputs flow through delay circuit 122 at multiplier 132 by spread-spectrum codes c2 spread spectrum, obtain signal b2c2 behind the spread spectrum, at multiplier 133 and spread-spectrum codes c1 spread spectrum, obtain signal b2c1 behind the spread spectrum.

4) step 24: with signal plus behind the spread spectrum, t1, t2 obtain transmitting

The input of adder 141 is: odd data stream and spread-spectrum codes c1 signal b1c1 and even data stream and the spread-spectrum codes c2 signal b2c2 behind the spread spectrum that obtains that multiplies each other that multiplies each other behind the spread spectrum that obtains.Adder 141 output base band transmit t1 through radio-frequency module (not shown), are launched by first antenna (not shown).

Similar, even data stream and signal b2c1 after spread-spectrum codes c1 mixes the spread spectrum that obtains and odd data flow with signal b1c2 after spread-spectrum codes c2 mixes the spread spectrum that obtains in adder 142 additions, obtain base band transmit t2,, launch by second antenna (not shown) through radio-frequency module (not shown).

t ₁＝b ₁c ₁+b ₂c ₂

(formula 1)

t ₂＝b ₂c ₁-b ₁c ₂

5) step 25: by two antennas transmit respectively t1, t2

Be appreciated that the present invention also can launch with many antennas.

Above-mentioned is handling process in the base station baseband circuit.Below in conjunction with Fig. 3,4, introduce the processing to received signal of mobile station receiver circuit.Under multipath fading, suppose that the channel from base station transmit antennas to the travelling carriage reception antenna comprises J different path.At this, the J paths that m bay comes out from the base station is used channel parameter h through independently Rayleigh fading _MjExpression (m=1,2, j=1,2......J).Particularly, the channel fading channel parameter h of the signal of first antenna emission _1jExpression; The channel fading channel parameter h of the signal of second antenna emission _2jExpression.Travelling carriage can be estimated fading channel and multipath delay according to the downward guide signal that the base station sends.Under the optimum reception condition, each composition of base station transmit signals has identical expectation power and reaches the complete quadrature of delay spread-spectrum codes.

The mobile station receiver circuit comprises two matched filters 311,312, two multipliers 321,322 that are connected with a matched filter respectively, the adder 331,332 that is connected with two multipliers, the decision device 341,342 that is connected with an adder respectively, the delayer 351 that is connected with decision device is connected interpolation with decision device and merges module 361 with delayer.

The t that transmits from first and second antenna transmission ₁, t ₂, respectively through multipath fading h ₁, h ₂After, the signal that obtains at the travelling carriage receiving terminal is

$r=\sqrt{\mathrm{\&rho;}}(\underset{j=1}{\overset{J}{\mathrm{\&Sigma;}}}{h}_{1j}(b_1{c}_{1j}+b_2{c}_{2j})+\underset{j=1}{\overset{J}{\mathrm{\&Sigma;}}}{h}_{2j}(b_2{c}_{1j}-b_1{c}_{2j}))+n$ (formula 2)

$=\sqrt{\mathrm{\&rho;}}(C_1{h}_1-C_2{h}_2){\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="A200810188360E00161.png,A200810188360E00171.png"\; state="\{\{state\}\}">b</figure-callout>}}_1+\sqrt{\mathrm{\&rho;}}(C_2{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="A200810188360E00161.png,A200810188360E00171.png"\; state="\{\{state\}\}">h</figure-callout>}}_1+C_1{h}_2){\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="A200810188360E00181.png,A200810188360E00182.png"\; state="\{\{state\}\}">b</figure-callout>}}_2+n$

Wherein, C ₁=[c _L1, Λ, c _LJ], h _l=[h _L1, Λ, h _LJ] T, l ∈ 1,2}; Suppose that noise n is that average is 0, variance is N ₀/ 2 white Gaussian noise vector is represented the expectation SNR (signal to noise ratio) of each multipath component with ρ, $\mathrm{\&rho;}=1/{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="A200810188360E00181.png,A200810188360E00182.png"\; state="\{\{state\}\}">n</figure-callout>}}^2.$

Travelling carriage receives received signal r by an antenna (not shown), carries out following processing:

1) step 41: divide the two-way despreading to received signal, obtain after first despreading signal behind the signal and second despreading

Received signal r matched filter 311 with postpone spread-spectrum codes C1 and multiply each other, export signal d1 after first despreading.Received signal r matched filter 312 with postpone spread-spectrum codes C2 and multiply each other, export signal d2 after second despreading.Wherein, postpone spread-spectrum codes C1, C2 and be input to matched filter 311 and 312 respectively by postponing spread-spectrum codes generation unit (not shown).Travelling carriage is estimated multipath delay, computing relay spread-spectrum codes according to the downward guide signal that the base station sends.After first despreading after the signal d1 and second despreading signal d2 be respectively:

${\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="A200810188360E00161.png,A200810188360E00171.png"\; state="\{\{state\}\}">d</figure-callout>}}_1=C_1^{H}r=\sqrt{\mathrm{\&rho;}}[R_{11}{h}_1-R_{12}{h}_2]{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="A200810188360E00161.png,A200810188360E00171.png"\; state="\{\{state\}\}">b</figure-callout>}}_1+\sqrt{\mathrm{\&rho;}}[R_{12}{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="A200810188360E00161.png,A200810188360E00171.png"\; state="\{\{state\}\}">h</figure-callout>}}_1+R_{11}{h}_2]{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="A200810188360E00181.png,A200810188360E00182.png"\; state="\{\{state\}\}">b</figure-callout>}}_2+C_1^{H}n$

(formula 3)

${\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="A200810188360E00181.png,A200810188360E00182.png"\; state="\{\{state\}\}">d</figure-callout>}}_2=C_2^{H}r=\sqrt{\mathrm{\&rho;}}[R_{21}{h}_1-R_{22}{h}_2]{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="A200810188360E00161.png,A200810188360E00171.png"\; state="\{\{state\}\}">b</figure-callout>}}_1+\sqrt{\mathrm{\&rho;}}[R_{22}{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="A200810188360E00161.png,A200810188360E00171.png"\; state="\{\{state\}\}">h</figure-callout>}}_1+R_{21}{h}_2]{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="A200810188360E00181.png,A200810188360E00182.png"\; state="\{\{state\}\}">b</figure-callout>}}_2+C_2^{H}n$

Here $R_{\mathrm{ij}}=C_i^H{C}_j,$ I=1 or 2, j=1 or 2.

2) step 42: to signal after first and second despreadings carry out respectively merging that the channel parameter weighting obtains signal after first and second despreadings with

Signal d1 multiplies each other with channel parameter vector h1 in multiplier 321 after first despreading, is input to adder 331 then; Signal d1 and channel parameter vector h1's is long-pending after first despreading, is input to adder 332 after anti-phase.

Similarly, signal d2 multiplies each other with channel parameter vector h2 in multiplier 322 after second despreading, is input to adder 333 then; Signal d2 and channel parameter vector h2's is long-pending after second despreading, is input to adder 331 after anti-phase.

Signal d2 and channel parameter vector h2 after adder 331, the second despreadings long-pending anti-phase (d2h2) with first despreading after signal d1 and channel parameter vector h1 amass (d1h1) addition, its output is the input of decision device 341.After signal d2 and channel parameter matrix h2 after adder 332, the second despreadings long-pending (d2h2) and first despreading signal d1 and channel parameter vector h1 amass anti-phase (d1h1) addition is imported decision device 342 then and is adjudicated.Need to prove that what travelling carriage of the present invention used is maximal ratio combiner.Travelling carriage has channel parameter generation unit (not shown) to estimate fading channel according to the downward guide signal that the base station sends, the calculating channel parameter, and import corresponding multiplier.Wherein, channel parameter vector h ₁=[h ₁₁, Λ, h _1J] ^T, h ₂=[h ₂₁, Λ, h _2J] ^T

3) step 43: with the merging of signal after first and second despreadings with adjudicate respectively, obtain recovering signal

Through the judgement of decision device 341 and 342, data b 1 and data flow b2 after just obtaining reducing.The judgement Calculation Method of decision device 341 is:

If the real part of decision device input signal is greater than zero, then b1 equals 1, explains with (formula 4a):

$\mathrm{Re}\{h_1^H{d}_1-h_2^H{d}_2\}\stackrel{{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="A200810188360E00161.png,A200810188360E00171.png"\; state="\{\{state\}\}">b</figure-callout>}}_1=1}{>}0$ (formula 4a)

If the real part of decision device input signal is less than zero, then whether b1 equals-1, explains with (formula 4b):

$\mathrm{Re}\{h_1^H{d}_1-h_2^H{d}_2\}\stackrel{{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="A200810188360E00161.png,A200810188360E00171.png"\; state="\{\{state\}\}">b</figure-callout>}}_1=-1}{<}0$ (formula 4b)

The judgement Calculation Method of decision device 342 is:

If the real part of decision device input signal is greater than zero, then b2 equals 1, explains with (formula 4c):

$\mathrm{Re}\{h_2^{\mathrm{<figure-callout\; id="1"\; label="H\; d"\; filenames="A200810188360E00161.png,A200810188360E00171.png"\; state="\{\{state\}\}">H</figure-callout>}}{d}_{}{}_1+h_1^H{d}_2\}\stackrel{{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="A200810188360E00181.png,A200810188360E00182.png"\; state="\{\{state\}\}">b</figure-callout>}}_2=1}{>}0$ (formula 4c)

If the real part of decision device input signal is less than zero, then b2 equals-1, explains with (formula 4d):

$\mathrm{Re}\{h_2^{\mathrm{<figure-callout\; id="1"\; label="H\; d"\; filenames="A200810188360E00161.png,A200810188360E00171.png"\; state="\{\{state\}\}">H</figure-callout>}}{d}_{}{}_1+h_1^H{d}_2\}\stackrel{{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="A200810188360E00181.png,A200810188360E00182.png"\; state="\{\{state\}\}">b</figure-callout>}}_2=-1}{<}0$ (formula 4d)

This shows, travelling carriage of the present invention be directly to the merging of signal after the signal after first despreading and second despreading with adjudicate, do not need to carry out complicated matrix computations, thereby the circuit design of simplifying reduces amount of calculation.

Step 44: during to the odd data curtain coating of reduction, the even data stream with reduction is merged into restoring data stream b then.

Reduction odd data stream b1 after the judgement send interpolation to merge module 36 through delay circuit 35 with reducing couple data flow b2.Interpolation merges module 36 odd and even data is flowed b1, and b2 replaces interpolation, is reduced into data flow b.Delay circuit 35 among Fig. 3 is identical with delay circuit 12 in the transmitter circuitry, gets same delay parameter.

For the effect of the inventive method is described, provide emulated data at this.

Further theoretical derivation can prove: under the very little situation of correlation of the delay spread-spectrum codes that the delay spread-spectrum codes and its even data of single user's odd data stream flows, and R _Ij≈ 0, i ≠ j, and i=1 or 2, j=1 or 2, or antenna for base station 1 is to the multipath channel h of travelling carriage ₁With the multipath channel h of antenna for base station 2 to travelling carriage ₂The very little situation of correlation under, $r_{\mathrm{ij}}=h_i^H{h}_j\&ap;0,$ The bit error rate expression formula of user of mobile station is

$P_e\&ap;Q\left(\sqrt{\mathrm{\&rho;}(h_1^H{R}_{11}{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="A200810188360E00161.png,A200810188360E00171.png"\; state="\{\{state\}\}">h</figure-callout>}}_1+h_2^H{R}_{22}{h}_2)}\right)$ (formula 5)

Obtain the error rate of Fig. 5 respectively by theoretical calculation formula 5 and Monte Carlo simulation.Compare with the single antenna design that does not adopt the STS technology, the STS scheme improves the bit error rate performance of system as can be seen.The curve of representing with solid line and dotted line among Fig. 5 is to work as the base station transmit antennas number under the multipath conditions to be respectively M=1,2 o'clock, and the relation curve of the bit error rate that the SNR of expectation and emulation obtain.In the error rate is 10 ^-2The time, the SNR of the STS system of theoretical value and simulation scenarios has improved about 4dB than a single aerial system.Here, the spread-spectrum codes c of use ₁And c ₂Be that length is 128 quadrature Walsh sign indicating number, because the existence of multipath, they are C through the form after the channel latency ₁=[c ₁₁c ₁₂], C ₂=[c ₂₁c ₂₂], postpone to get 10 code words.

In aforementioned introduction, only relate to the situation of single user system.Yet in actual applications, system is the multi-user.Because the existence of symbol-interference (ISI) between the user, along with increasing of number of users, its interference effect increases, and causes systematic function to descend significantly.

The situation of research when system is K user below, its design principle is consistent with the front with running environment, then k user transmit for

$t_1^{\left(k\right)}=b_1^{\left(k\right)}{c}_1^{\left(k\right)}+b_2^{\left(k\right)}{c}_2^{\left(k\right)}$

(formula 6)

$t_2^{\left(k\right)}=b_2^{\left(k\right)}{c}_1^{\left(k\right)}-b_1^{\left(k\right)}{c}_2^{\left(k\right)}$

Under multipath channel (J=2) decline, channel parameter is arranged

$H^{\left(k\right)}=\left[\begin{array}{c}{h}_1^{\left(k\right)}\\ h_2^{\left(k\right)}\end{array}\right]$ (formula 7)

Similar with formula 2, k user's the base station that receives is for its signal

$r^{\left(k\right)}=h_1^{\left(k\right)}\&CenterDot;t_1^{\left(k\right)}+h_2^{\left(k\right)}\&CenterDot;t_2^{\left(k\right)}+n^{\left(k\right)}$

$=\sqrt{\mathrm{\&rho;}}(\underset{j=1}{\overset{J}{\mathrm{\&Sigma;}}}{h}_{1j}^k(b_1^{\left(k\right)}{c}_{1j}^{\left(k\right)}+b_2^{\left(k\right)}{c}_{2j}^{\left(k\right)})+\underset{j=1}{\overset{J}{\mathrm{\&Sigma;}}}{h}_{2j}^{\left(k\right)}(b_2^{\left(k\right)}{c}_{1j}^{\left(k\right)}-b_1^{\left(k\right)}{c}_{2j}^{\left(k\right)}))+n^{\left(k\right)}$ (formula 8)

$=\sqrt{\mathrm{\&rho;}}(C_1^{\left(k\right)}{h}_1^{\left(k\right)}-C_2^{\left(k\right)}{h}_2^{\left(k\right)})b_1^{\left(k\right)}+\sqrt{\mathrm{\&rho;}}(C_2^{\left(k\right)}{h}_1^{\left(k\right)}+C_1^{\left(k\right)}{h}_2^{\left(k\right)})b_2^{\left(k\right)}+n^{\left(k\right)}$

Symbolic representation in the formula (8) is consistent with formula (2).Then the total received signal of receiver end is

$r=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{r}^{\left(k\right)}$ (K is a total number of users) (formula 9)

Similarly, through the signal of separating spread spectrum be

$d_1^{\left(k\right)}={\left(C_1^{\left(k\right)}\right)}^{H}r={\left(C_1^{\left(k\right)}\right)}^H\&CenterDot;\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{r}^{\left(k\right)}={\left(C_1^{\left(k\right)}\right)}^H{r}^{\left(k\right)}+\underset{m\&NotEqual;k}{\overset{K}{\underset{m=1}{\mathrm{\&Sigma;}}}}{\left(C_1^{\left(k\right)}\right)}^H\&CenterDot;r^{\left(m\right)}$ (formula 10a)

$d_2^{\left(k\right)}={\left(C_2^{\left(k\right)}\right)}^{H}r={\left(C_2^{\left(k\right)}\right)}^H\&CenterDot;\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{r}^{\left(k\right)}={\left(C_2^{\left(k\right)}\right)}^H{r}^{\left(k\right)}+\underset{m\&NotEqual;k}{\overset{K}{\underset{m=1}{\mathrm{\&Sigma;}}}}{\left(C_2^{\left(k\right)}\right)}^H\&CenterDot;r^{\left(m\right)}$ (formula 10b)

The data flow that reduction obtains is

${\left(h_1^{\left(k\right)}\right)}^H{d}_1^{\left(k\right)}-{\left(h_2^{\left(k\right)}\right)}^H{d}_2^{\left(k\right)}$

$={\left(h_1^{\left(k\right)}\right)}^H{\left(C_1^{\left(k\right)}\right)}^H{r}^{\left(k\right)}+\left({\left(h_1^{\left(k\right)}\right)}^H{\left(C_1^{\left(k\right)}\right)}^H\underset{m\&NotEqual;k}{\overset{K}{\underset{m=1}{\mathrm{\&Sigma;}}}}{r}^{\left(m\right)}\right)$

$-{\left(h_2^{\left(k\right)}\right)}^H{\left(C_2^{\left(k\right)}\right)}^H{r}^{\left(k\right)}-\left({\left(h_2^{\left(k\right)}\right)}^H{\left(C_2^{\left(k\right)}\right)}^H\underset{m\&NotEqual;k}{\overset{K}{\underset{m=1}{\mathrm{\&Sigma;}}}}{r}^{\left(m\right)}\right)$ (formula 11a)

${\left(h_2^{\left(k\right)}\right)}^H{d}_1^{\left(k\right)}+{\left(h_1^{\left(k\right)}\right)}^H{d}_2^{\left(k\right)}$

$={\left(h_2^{\left(k\right)}\right)}^H{\left(C_1^{\left(k\right)}\right)}^H{r}^{\left(k\right)}+\left({\left(h_2^{\left(k\right)}\right)}^H{\left(C_1^{\left(k\right)}\right)}^H\underset{m\&NotEqual;k}{\overset{K}{\underset{m=1}{\mathrm{\&Sigma;}}}}{r}^{\left(m\right)}\right)$

$+{\left(h_1^{\left(k\right)}\right)}^H{\left(C_2^{\left(k\right)}\right)}^H{r}^{\left(k\right)}+\left({\left(h_1^{\left(k\right)}\right)}^H{\left(C_2^{\left(k\right)}\right)}^H\underset{m\&NotEqual;k}{\overset{K}{\underset{m=1}{\mathrm{\&Sigma;}}}}{r}^{\left(m\right)}\right)$ (formula 11b)

By formula (11) as can be seen,

With

Part be the multi-user than the additional part of single user situation, promptly get base station two antennas to the multiple access of travelling carriage k interference (MAI)

${\mathrm{MAI}}_1^{\left(k\right)}={\left(h_1^{\left(k\right)}\right)}^H\left(C_1^{\left(k\right)}\right)\underset{m\&NotEqual;k}{\overset{K}{\underset{m=1}{\mathrm{\&Sigma;}}}}\left(C_1^{\left(m\right)}\right)\left(h_1^{\left(m\right)}\right)$

${\mathrm{MAI}}_2^{\left(k\right)}={\left(h_2^{\left(k\right)}\right)}^H\left(C_2^{\left(k\right)}\right)\underset{m\&NotEqual;k}{\overset{K}{\underset{m=1}{\mathrm{\&Sigma;}}}}\left(C_2^{\left(m\right)}\right)\left(h_2^{\left(m\right)}\right)$ (formula 12)

Thereby total multiple access disturbs (MAI) to be

${\mathrm{MAI}}^{\left(k\right)}={\mathrm{MAI}}_1^{\left(k\right)}+{\mathrm{MAI}}_2^{\left(k\right)}$ (formula 13)

Use spread spectrum sequence C 1 and C2 despreading in the mobile station receiving circuit of the present invention, h1 and h2 weighting, the method judgement that decision device adopts (formula 4) realizes the inhibition to MAI.

The present invention has greatly improved to error rate of system during the multi-user.

System of the present invention when two transmitting antenna multi-user, k mobile subscriber's the error rate

$P_{e2}^{\left(k\right)}=Q\left(\sqrt{\frac{{\left(h_1^{\left(k\right)}\right)}^H{R}_{11}^{\left(k\right)}{h}_1^{\left(k\right)}+{\left(h_2^{\left(k\right)}\right)}^H{R}_{22}^{\left(k\right)}{h}_2^{\left(k\right)}}{K/\mathrm{\&rho;}+{\mathrm{MAI}}^{\left(k\right)}}}\right)$ (formula 14)

Work as K=1 in the formula 14, then changing in quality is formula 14.So a kind of special circumstances that two transmitting antenna list users of formula 5 are formula 14.

Do not adopt system of the present invention when single transmit antenna multi-user, k mobile subscriber's the error rate

$P_{e1}^{\left(k\right)}=Q\left(\sqrt{\frac{{\left(h^{\left(k\right)}\right)}^H{R}_{11}^{\left(k\right)}{h}^{\left(k\right)}}{K/\mathrm{\&rho;}+{\left(h^{\left(k\right)}\right)}^H\left(C^{\left(k\right)}\right)\underset{m\&NotEqual;k}{\overset{K}{\underset{m=1}{\mathrm{\&Sigma;}}}}\left(C^{\left(m\right)}\right)\left(h^{\left(m\right)}\right)}}\right)$ (formula 15)

In above-mentioned formula, correlation matrix $R_{\mathrm{ij}}=C_i^H{C}_j$ Change with the locus of travelling carriage changes, and this needs travelling carriage to determine C by channel estimating _i, C _j, and then definite R _Ij

In order to verify the validity of the technology of the present invention, (Monte Carlo simulation: the base station sends data 10 with link simulation to adopt Theoretical Calculation (according to formula (14) and (15)) ⁵Bit is surveyed the bit error rate that travelling carriage receives data), with it with do not adopt a single aerial system performance of the present invention to compare.Emulation of the present invention does not add the channel error correction coding/decoding.The spread-spectrum codes c that uses ₁And c ₂Be that length is 64 quadrature Walsh sign indicating number, consider the situation of two multipaths, c ₁And c ₂Through the form after the channel latency is C ₁=[c ₁₁c ₁₂], C ₂=[c ₂₁c ₂₂], postpone to get 10 code words.Fading channel is at random: the fading channel matrix during as 16 users of following emulation

h11(1，2，...，16)＝[0.6552 0.8376 0.6284 0.5747

0.5947 0.5657 0.7165 0.5113 0.7764 0.5107

0.8141 0.7006 0.9827 0.8066 0.7036 0.5150]；

h12(1，2，...，16)＝[0.3448 0.1624 0.3716 0.4253

0.4053 0.4343 0.2835 0.4887 0.2236 0.4893

0.1859 0.2994 0.0173 0.1934 0.2964 0.4850]；

h21(1，2，...，16)＝[0.8854 0.6649 0.6346 0.8600

0.5668 0.8230 0.6739 0.9994 0.9616 0.9411

0.6397 0.5485 0.7382 0.5973 0.9507 0.5711]；

h22(1，2，...，16)＝[0.1146 0.3351 0.3654 0.1400

0.4332 0.1770 0.3261 0.0006 0.0384 0.0589

0.3603 0.4515 0.2618 0.4027 0.0493 0.4289]。

(1) there is 4 users' situation in system

Among Fig. 6 (a), solid line is represented the situation of change of the theoretical error rate of STS system with the SNR of expectation, and asterisk place curve is the situation of change of the emulation error rate of STS system with the SNR of expectation; Dotted line is represented the situation of the theoretical error rate of a single aerial system with the SNR variation of expectation, and circle place curve is the situation of change of the emulation error rate.As can be seen, when the error rate be 10 ^-2The time, adopted system SNR of the present invention all increasing about 7.6dB on the theoretical value He on the simulation value than the system SNR that does not adopt this technology.Because in simulation process, the noise of generation is at random, and signal go back original judgment makes theoretical value and simulation value produce error, so relative its theoretical error performance of error performance of the STS that obtains of emulation will differ from.

(2) there is 16 users' situation in system

Fig. 6 (b) expression be 16 users the time system error performance.Find out easily,, adopted the error rate of the system of the technology of the present invention to reduce rapidly, and do not adopt the theoretical value and the simulation value of the error rate of the system of this technology all to remain on about 20% as SNR during greater than 8dB.

Can also see that simultaneously the difference of the error performance during 16 users during than 4 users is a little, this is that the influence that the number of users increase is disturbed multiple access increases, and causes error performance to descend to some extent because under the relevant situation of channel.Along with the proportion in received signal of the intersymbol interference between the user increases, do not adopt the error performance of the system of this aspect method can not accept this moment, and the error performance of the system of employing the technology of the present invention still requires the SNR of system greater than 14dB still in normal range of operation.

By the contrast of design sketch, illustrate that technology of the present invention is a kind of otherwise effective technique, it has improved the bit error rate performance of system to a certain extent.

Though above described the present invention by embodiment, those of ordinary skills know, the present invention has many distortion and variation and does not break away from spirit of the present invention, appended claim will comprise these distortion and variation.

Claims (6)

1, a kind of mobile station receiving circuit of using the cdma system space-time spectrum extending method, the receiving circuit of travelling carriage comprises two and the matched filter that connects, import received signal respectively, two multipliers are connected with two matched filters respectively, two adders are connected with multiplier respectively, and the decision device that is connected with two adders respectively, wherein the input of each adder is output anti-phase of the output of a multiplier and another multiplier.

2, mobile station receiving circuit as claimed in claim 1 is characterized in that, mobile station receiving circuit only has an antenna, in order to received signal and be input to matched filter.

3, mobile station receiving circuit as claimed in claim 1 is characterized in that, comprises a delayer and merges module, exports to delayer for one in its decision device, and then with the output of another decision device as the input that merges module.

4, mobile station receiving circuit as claimed in claim 1 is characterized in that, the input of matched filter is received signal and delay spread-spectrum codes, and output is signal after the despreading, and this delay spread-spectrum codes is provided by travelling carriage.

5, mobile station receiving circuit as claimed in claim 1 is characterized in that, the input of multiplier is signal and a corresponding channel parameter after the despreading, and this channel parameter is estimated by travelling carriage.

6, mobile station receiving circuit as claimed in claim 1 is characterized in that, two decision devices are carried out following calculating:

If the real part of decision device input signal then exports 1 greater than zero,

If the real part of decision device input signal less than zero, then exports-1.

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