CN101521535B - Base station transmitting circuit for CDMA system sparetime spread spectrum method - Google Patents

Abstract

The invention relates to a base station transmitting circuit for a CDMA system sparetime spread spectrum method, which comprises two lower sampling modules, a time delay module, a plurality of spread spectrum devices and two adders, wherein the time delay module is connected with one lower sampling module; the plurality of the spread spectrum devices are connected with the lower sampling modules or the time delay module respectively; the two adders are connected with the spread spectrum devices; and the two lower sampling modules sample a data stream into two data streams, wherein one data stream is delayed by the time delay module and enters the spread spectrum device. The time delay module adjusts the time difference between the two data streams, so that the time difference is equal to atime difference of the two data streams when the space between two transmitting antennas is 10 to 15 times of the wavelength of a radio frequency signal. The space between the transmitting antennas c an be not more than 10 to 15 times of the wavelength of a transmitting signal. The space between the transmitting antennas of the base station can be in the range from more than four times of the wavelength of the transmitting signal to less than 10 to 15 times of the wavelength of the transmitting signal, so the base station transmitting circuit is more suitable for engineering, in addition, the circuit design is simple, and spread spectrum codes of an odd data stream and an even data stream are obtained by a spread spectrum code.

Description

The base station radiating circuit of cdma system space-time spectrum extending method

The application is dividing an application of application for a patent for invention " cdma system space-time spectrum extending method and corresponding mobile station receiving circuit ", the applying date of original application: on March 12nd, 2004, application number: 200410008815.0, invention and created name: cdma system space-time spectrum extending method.

Technical field

The present invention relates to the base station radiating 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 forward direction and the reverse link of cdma system, can the Effective Raise 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 Transmit Diversity)

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

(2) another kind is the data that two separate antenna emissions of space-time spectrum extending diversity mode STS (Space Time Spreading) cdma base station usage space have interweaved, use identical original Walsh code channel, odd data stream and even data stream jointly rather than are dividually gone out by two antenna transmissions.

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 although available two transmitting antennas realize, be to obtain take the bandwidth of twice as cost, 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 the 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 on Space-Time Spreading) that is used for wideband CDMA system is described in detail this.

In the existing space-time spectrum extending technology (STS), the spacing of base station transmit antennas must be uncorrelated mutually greater than the signal of 10-15 times of radiofrequency signal wavelength guarantee arrival antenna array unit, 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 need to have 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.Reception despreading algorithm in the aforementioned documents need to carry out a large amount of matrix operations, thereby is difficult to realize.

The present invention will address the above problem, and eliminate multiple access in the situation of multi-user multi-path and disturb, and improve the error rate of system performance.

Summary of the invention

The objective of the invention is, proposed the base station transmitting diversity circuit of cdma system space-time spectrum extending method, can realize Full diversity in the situation without the extra bandwidth resource, each user only needs a spread-spectrum codes, is easy to realize.Implementation of the present invention is:

The base station radiating circuit of cdma system space-time spectrum extending method, 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 greater than half scope to the wavelength that doubly transmits less than 10-15 of wavelength that transmits, be more applicable for engineering and use.And 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 lower decimation blocks, the time delay module that is connected with a lower decimation blocks, a plurality of frequency multipliers that are connected with lower decimation blocks or time delay module respectively and two adders that are connected with frequency multiplier, two lower 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.

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 in accordance with the following steps:

1) data flow with each user 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 in accordance with the following steps:

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

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

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

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,

, " 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 code 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 transmitting 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 step 7) in the method for receiving circuit judgement of travelling carriage be: the decision device of the receiving circuit of travelling carriage (341) to the first despreading after the merging of signal with the method for adjudicating calculating be:

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

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

The decision device of the receiving circuit of travelling carriage (342) to the second despreading after the merging of signal with the method for adjudicating calculating 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, step 7) further comprise in: the receiving circuit of travelling carriage to the first despreading after signal merge and court verdict delay time, then with the second despreading after signal merge and court verdict merge, obtain restoring data.

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

Another object of the present invention is to have proposed to use the mobile station receiving circuit of 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, can suppress the multiple access interference MAI (multiple access interference) in multi-user's situation.

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, input receives 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.

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 receive data of the present invention can obtain diversity gain, significantly improves on the whole the information transmission quality of wireless communication system.And the present invention can eliminate to a certain extent multiple access 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 transmitting 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 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.

Travelling carriage error rate comparative graph when Fig. 5 is alone family in the system of the system of application single transmit antenna base station and application base station of the present invention.

Fig. 6 (a) and (b) be respectively 4 and use the system of the inventive method during 16 user and do not use the error performance comparative graph of the system of the inventive method.

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 only has 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 lower decimation blocks 111 and 112, time delay module 122, frequency multiplier (multiplier) 131,132,133,134 and adder 141 and 142.

In conjunction with Fig. 2, the step that base station baseband is processed is:

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

Each user's data flow b is divided into two-way, obtains odd data stream b1 and even data stream b2 through lower decimation blocks 111 and 112.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 odd and even data after the adjustment stream equals two transmitting antenna spacings when being 10-15 times of radiofrequency signal wavelength, therefore, if use base station of the present invention, two antenna distances on this 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 that travelling carriage receives the irrelevance of signal.Base station of the present invention transmitting diversity circuit provides time diversity by the time difference between time delay module 122 adjustment odd data streams and the even data stream.But two antennas of base station are very little to the multipath channel correlation of travelling carriage, can make this moment the correlation of the delay spread-spectrum codes that delay spread-spectrum codes and its even data of the odd data stream at alone family flow very little.Therefore, two of the base station antenna distances need greater than 1/2nd radiofrequency signal wavelength.

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.Therefore, in this case, baseband circuit 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 lower 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,

" H " represents complex-conjugate transpose.

Calculate for convenient, among the present invention, spread-spectrum codes c1, c2 are calculated by one 64 Walsh code 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 code sequence c0, so can not increase the existing spread spectrum yardage of system.Be appreciated that as long as satisfy

Quadrature spread-spectrum codes c1, the c2 of condition just can realize the present invention.

The even data of lower 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, signal b1c2 is in adder 142 additions behind the spread spectrum that signal b2c1 and odd data stream and spread-spectrum codes c2 are mixed to get behind the spread spectrum that even data stream and spread-spectrum codes c1 are mixed to get, obtain base band transmit t2, through radio-frequency module (not shown), launched by second antenna (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 be with many antenna transmissions.

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, m bay J paths is out used channel parameter h through independently Rayleigh fading from the base station _MjExpression (m=1,2, j=1,2......J).Particularly, the channel fading of the signal of first antenna transmission channel parameter h _1jExpression; The channel fading of the signal of second antenna transmission channel parameter h _2jExpression.Travelling carriage can be according to downward guide Signal estimation fading channel and the multipath delay of base station transmission.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 the transmission of the first and second antennas ₁, t ₂, respectively through multipath fading h ₁, h ₂After, the signal that obtains at the travelling carriage receiving terminal is

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

$=\sqrt{\mathrm{\&rho;}}(C_1{h}_1-C_2{h}_2){\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HSB00000764563600011.png"\; state="\{\{state\}\}">b</figure-callout>}}_1+\sqrt{\mathrm{\&rho;}}(C_2{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HSB00000764563600011.png"\; state="\{\{state\}\}">h</figure-callout>}}_1+C_1{h}_2){\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HSB00000764563600031.png,HSB00000764563600033.png"\; state="\{\{state\}\}">b</figure-callout>}}_2+n$

Wherein, C ₁=[c _L1..., c _LJ], h _l=[h _L1..., h _LJ] ^T, l ∈ { 1,2}; Suppose that noise n is that average is 0, variance is N ₀/ 2 white Gaussian noise vector represents the expectation SNR (signal to noise ratio) of each multipath component with ρ,

Travelling carriage receives by an antenna (not shown) and receives signal r, is handled as follows:

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

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

${\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="HSB00000764563600011.png"\; state="\{\{state\}\}">d</figure-callout>}}_1=C_1^{H}r=\sqrt{\mathrm{\&rho;}}[R_{11}{h}_1-R_{12}{h}_2]{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HSB00000764563600011.png"\; state="\{\{state\}\}">b</figure-callout>}}_1+\sqrt{\mathrm{\&rho;}}[R_{12}{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HSB00000764563600011.png"\; state="\{\{state\}\}">h</figure-callout>}}_1+R_{11}{h}_2]{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HSB00000764563600031.png,HSB00000764563600033.png"\; state="\{\{state\}\}">b</figure-callout>}}_2+C_1^{H}n$ (formula 3)

${\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HSB00000764563600031.png,HSB00000764563600033.png"\; state="\{\{state\}\}">d</figure-callout>}}_2=C_2^{H}r=\sqrt{\mathrm{\&rho;}}[R_{21}{h}_1-R_{22}{h}_2]{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HSB00000764563600011.png"\; state="\{\{state\}\}">b</figure-callout>}}_1+\sqrt{\mathrm{\&rho;}}[R_{22}{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HSB00000764563600011.png"\; state="\{\{state\}\}">h</figure-callout>}}_1+R_{21}{h}_2]{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HSB00000764563600031.png,HSB00000764563600033.png"\; state="\{\{state\}\}">b</figure-callout>}}_2+C_2^{H}n$

Here

I=1 or 2, j=1 or 2.

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

Signal d1 multiplies each other with channel parameter vector h1 in multiplier 321 after the first despreading, then is input to adder 331; Signal d1 and channel parameter vector h1's is long-pending after the 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 the second despreading, then is input to adder 333; Signal d2 and channel parameter vector h2's is long-pending after the 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 the 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 the first despreading signal d1 and channel parameter vector h1 amass anti-phase (then d1h1) addition is inputted decision device 342 and is adjudicated.Need to prove that what travelling carriage of the present invention used is maximal ratio combiner.The downward guide Signal estimation fading channel that travelling carriage has channel parameter generation unit (not shown) to send according to the base station calculates channel parameter, and inputs corresponding multiplier.Wherein, channel parameter vector h ₁=[h ₁₁..., h _1J] ^T, h ₂=[h ₂₁..., h _2J] ^T

3) step 43: with the merging of signal after the 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 method that the judgement of decision device 341 is calculated is:

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

$\mathrm{Re}{\{h_1^H{d}_1-h_2^H{d}_2\}}^{{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HSB00000764563600011.png"\; state="\{\{state\}\}">b</figure-callout>}}_1=1}>0$ (formula 4a)

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

$\mathrm{Re}{\{h_1^H{d}_1-h_2^H{d}_2\}}^{{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HSB00000764563600011.png"\; state="\{\{state\}\}">b</figure-callout>}}_1=-1}<0$ (formula 4b)

The method that the judgement of decision device 342 is calculated is:

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

$\mathrm{Re}{\{h_2^{\mathrm{<figure-callout\; id="1"\; label="H\; d"\; filenames="HSB00000764563600011.png"\; state="\{\{state\}\}">H</figure-callout>}}{d}_{}{}_1+h_1^H{d}_2\}}^{{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HSB00000764563600031.png,HSB00000764563600033.png"\; state="\{\{state\}\}">b</figure-callout>}}_2=1}>0$ (formula 4c)

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

$\mathrm{Re}{\{h_2^{\mathrm{<figure-callout\; id="1"\; label="H\; d"\; filenames="HSB00000764563600011.png"\; state="\{\{state\}\}">H</figure-callout>}}{d}_{}{}_1+h_1^H{d}_2\}}^{{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HSB00000764563600031.png,HSB00000764563600033.png"\; state="\{\{state\}\}">b</figure-callout>}}_2=-1}<0$ (formula 4d)

This shows that travelling carriage of the present invention is direct merging to signal after signal after the first despreading and the second despreading and adjudicates, and 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, then the even data stream with reduction is merged into restoring data stream b.

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: in the very little situation of correlation of the delay spread-spectrum codes that delay spread-spectrum codes and its even data of the odd data at alone family 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,

The bit error rate expression formula of user of mobile station is

$P_e\&ap;Q\left(\sqrt{\mathrm{\&rho;}(h_1^H{R}_{11}{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HSB00000764563600011.png"\; state="\{\{state\}\}">h</figure-callout>}}_1+h_2^H{R}_{22}{h}_2)}\right)$ (formula 5)

Obtained respectively the error rate of Fig. 5 by theoretical calculation formula 5 and Monte Carlo simulation.Compare with the single antenna design that does not adopt the STS technology, can find out that the STS scheme improves the bit error rate performance of system.The curve that represents 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.Be 10 in the error rate ^-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 code, 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 significantly to descend.

The below research situation when system is K user, 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 signal that the base station is transmitted to it that receives is

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

$=\sqrt{\mathrm{\&rho;}}(\underset{j=1}{\overset{J}{\mathrm{\&Sigma;}}}{h}_{1j}^{\left(k\right)}(b_1^{\left(k\right)}{c}_{1j}^{\left(k\right)}+b_2^{\left(k\right)}{c}_{2j}^{\left(k\right)})+\underset{j=1}{\overset{J}{\mathrm{\&Sigma;}}}{h}_{2j}^{\left(k\right)}(b_2^{\left(k\right)}{c}_{1j}^{\left(k\right)}-b_1^{\left(k\right)}{c}_{2j}^{\left(k\right)}))+n^{\left(k\right)}$ (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 reception signal of receiver end is

$r=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{r}^{\left(k\right)}$ (K is 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)

Can be found out by formula (11),

Part be the multi-user than the additional part of alone family situation, namely get base station two antennas to the multiple access of travelling carriage k and disturb (MAI)

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

$\mathrm{MA}{I}_2^{\left(k\right)}={\left(h_2^{\left(k\right)}\right)}^H\left(C_2^{\left(k\right)}\right)\underset{m\&NotEqual;k}{\overset{K}{\underset{m=1}{\mathrm{\&Sigma;}}}}\left(C_2^{\left(m\right)}\right)\left(h_2^{\left(m\right)}\right)$ (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 the alone family of two transmitting antennas of formula 5 is a kind of special circumstances of 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

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, adopt theoretical (according to formula (14) and (15)) and the link simulation (Monte Carlo simulation: base station transmission data 10 of calculating ⁵Bit is surveyed the bit error rate of travelling carriage receive 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 code, consider the situation of two multipaths, c ₁And c ₂Form after the process 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 such as 16 users of following emulation

h11(1，2，...，16)＝[0.6552?0.8376?0.6284?0.57470.5947?0.5657?0.7165?0.5113?0.7764?0.51070.8141?0.7006?0.9827?0.8066?0.7036?0.5150]；

h12(1，2，...，16)＝[0.3448?0.1624?0.3716?0.42530.4053?0.4343?0.2835?0.4887?0.2236?0.48930.1859?0.2994?0.0173?0.1934?0.2964?0.4850]；

h21(1，2，...，16)＝[0.8854?0.6649?0.6346?0.86000.5668?0.8230?0.6739?0.9994?0.9616?0.94110.6397?0.5485?0.7382?0.5973?0.9507?0.5711]；

h22(1，2，...，16)＝[0.1146?0.3351?0.3654?0.14000.4332?0.1770?0.3261?0.0006?0.0384?0.05890.3603?0.4515?0.2618?0.4027?0.0493?0.4289]。

(1) there is 4 users' situation in system

Among Fig. 6 (a), solid line represents the theoretical error rate of STS system with the situation of change of the SNR of expectation, and asterisk place curve is that the Simulated BER of STS system is with the situation of change of the SNR of expectation; Dotted line represents the theoretical error rate of a single aerial system with the situation of the SNR variation of expectation, and circle place curve is the situation of change of Simulated BER.Can find out, when the error rate is 10 ^-2The time, adopted system SNR of the present invention all increasing about 7.6dB than the system SNR that does not adopt this technology on the theoretical value He on the simulation value.Because in simulation process, the noise of generation is at random, and signal go back original judgment so that 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 user the time system error performance.Find out easily, as SNR during greater than 8dB, adopted the error rate of the system of the technology of the present invention to reduce rapidly, and do not adopt theoretical value and the simulation value of the error rate of the system of this technology all to remain on about 20%.

Can also see that simultaneously the difference of the error performance during 16 user during than 4 user is a little, this is that the impact that the number of users increase is disturbed multiple access increases, and causes error performance to descend to some extent because in the relevant situation of channel.Along with the proportion in receiving 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 effective technology, it has improved the bit error rate performance of system to a certain extent.

Although 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 (5)

1. use the base station radiating circuit of cdma system space-time spectrum extending method, it is characterized in that, comprise two lower decimation blocks, the time delay module that is connected with a lower decimation blocks, a plurality of frequency multipliers that are connected with lower decimation blocks or time delay module respectively and two adders that are connected with frequency multiplier, two lower decimation blocks are sampled to two data flow with data flow, wherein a data flow enters frequency multiplier after the time delay module time-delay, another data flow directly enters frequency multiplier, the addition of frequency multiplier output signal, t1, t2 obtain transmitting.

2. the base station radiating circuit of cdma system space-time spectrum extending method as claimed in claim 1, it is characterized in that, 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.

3. the base station radiating circuit of cdma system space-time spectrum extending method as claimed in claim 1 is characterized in that, one group of quadrature spread-spectrum codes c1, c2 that frequency multiplier uses obtain c by a Walsh code sequence c0 ₁=[c ₀c ₀], c ₂=[c ₀-c ₀], other one group of quadrature spread-spectrum codes c1, c2 are c ₁=[c ₀0], c ₂=[0 c ₀].

4. the base station radiating circuit of cdma system space-time spectrum extending method as claimed in claim 1 is characterized in that, frequency multiplier uses quadrature spread-spectrum codes c1, c2 respectively to two data flow spread spectrums.

5. frequency multiplier uses quadrature spread-spectrum codes c1, c2 respectively to two data flow spread spectrums as claimed in claim 4, the even data that it is characterized in that 112 outputs of lower decimation blocks 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, with signal plus behind the spread spectrum, t1, t2 obtain transmitting.

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