CN100454795C - Adaptive space time closed-loop transmitting diversity method and its system - Google Patents

Abstract

The present invention discloses a self-adaptive space-time closed-loop transmission diversity method and a system thereof. In each time interval, a symbol to be transmitted is coded in space and time; two paths of signals are output and are sent to two groups of antennas after being respectively amplified. The two paths of signals are sent to a mobile terminal which estimates each path of signals from the antennas and figures out and compares the powers of the first group of antennas and the second groups of antennas to obtain FBI bits. The FBI bits are transmitted to a base station through an uplink channel; the base station stores the FBI bits into a delay wire; the FBI bits in the delay wire are restored into power ratios; the weights of the transmitting powers of the first group of antennas and the second groups of antennas are figured out according to the power ratios; the transmitting powers of the two groups of antennas are adjusted. The present invention can adjust the transmitting powers of the two groups of transmitting antennas in a self-adaptive mode. Compared with an open-ring mode, the diversity gain is larger.

Description

Closed-Loop Transmit Diversity method and system thereof during a kind of adaptive space

Technical field

The present invention relates to the space-time emission diversity technology, relate in particular to a kind of space-time emission diversity method and device thereof of adjusting signal transmission power with adaptive mode in real time.

Background technology

Based on code division multiple access (Code Division Multiple Access, CDMA) third generation (3G of mode, Third Generation) mobile communication system wideband CDMA (WCDMA, Wideband CDMA) in the standard, share same section frequency range owing to the different user of users different in the same sub-district and adjacent cell is interior at one time, therefore, there is interference each other in the user, these interference-limited power system capacity and rate of information throughout.In order to improve power system capacity, can adopt multiple deversity scheme, as technology such as rake, space diversity and antenna diversities.In the system that adopts diversity technique, the same information content has a plurality of multi-form separate copies, after these separate copies are received the machine reception, (MaximumLikelihood, ML) principle make full use of the redundancy properties of information according to maximum likelihood, certain in addition special processing, can significantly reduce the bit error rate of transmission information, and reduce the required energy of wireless data transmission, thereby reduce interfering with each other between the user.As seen, diversity technique can improve power system capacity effectively.

Development of semiconductor, feasible transmit diversity more than two antennas becomes possibility; Along with the number of transmit antennas purpose increases, it is bigger that institute obtains diversity gain.In existing CDMA standard, four antenna transmit diversities mainly contain open loop space-time emission diversity method (Open-loop STTD), in this emission diversity method, owing to lack information to the current wireless channel, cause two groups of transmitting antennas always to be launched in the mode of constant power, can not to the time wireless channel that becomes carry out adaptive adjustment, thereby have certain performance loss.

Summary of the invention

For addressing the above problem, Closed-Loop Transmit Diversity method when the object of the invention is to propose a kind of adaptive space can self adaptation be adjusted the transmitting power of two groups of transmitting antennas, improves diversity gain.

Another object of the present invention is to propose a kind of system of Closed-Loop Transmit Diversity method when realizing above-mentioned adaptive space.

For achieving the above object, technical solution of the present invention is as follows:

Closed-Loop Transmit Diversity method during a kind of adaptive space may further comprise the steps at least:

In each time slot,

A, base station are carried out armed symbol Space Time Coding and are exported two paths of signals;

After amplifying respectively, b, two paths of signals deliver to two groups of antennas, every group of antenna is made up of two antennas, between two antennas in first group of antenna, and with fixing differing two paths of signals is sent to portable terminal between two antennas in second group of antenna, and two groups of antennas to differ the retention time identical;

C, portable terminal are estimated each the footpath signal from each root antenna, obtain the compound channel response of corresponding two groups of antennas respectively;

D, according to the compound channel RESPONSE CALCULATION go out first group of antenna and second group of antenna power and compared, if the power of first group of antenna greater than the power of second group of antenna, then feedback signal (FeedBackIndication, FBI) bit is 1, otherwise is 0;

E, FBI bit transfer to the base station by up channel, and what the base station will be received recently is no less than 1 FBI bit storage in delay line;

F, according to the mapping relations of predetermined FBI bit and power ratio, the FBI bit in the delay line is reverted to power ratio;

G, calculate the weight of first group of antenna and second group of antenna transmitting power, and adjust the transmitting power of two antennas according to power ratio.

Step a further comprises: symbol to be launched is that cell block is encoded according to per two symbols, the output two paths of signals, and one the tunnel is identical with incoming symbol, and another road is backward and first symbol negate of incoming symbol conjugation.

It all is 1 that two groups of signals described in the step b amplify the amplification factor that adopts; Described fixed phase difference is π.

Obtain the compound channel response of corresponding two groups of antennas respectively described in the step c and adopt following formula:

$\left\{\begin{array}{c}\mathrm{\α}=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{\mathrm{\α}}_k=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}(h_{1k}+h_{2k}{e}^{\mathrm{j\φ}})\\ \mathrm{\β}=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{\mathrm{\β}}_k=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}(h_{3k}+h_{4k}{e}^{\mathrm{j\ψ}})\end{array}\right.,$

Wherein α is the compound channel response of corresponding first group of antenna, and β is the compound channel response of corresponding second group of antenna, and K is the footpath number of wireless channel transmission, h _1kAnd h _2kBe each footpath radio channel response of first group of antenna, h _3kAnd h _4kBe each footpath radio channel response of second group of antenna, φ and ψ are fixed phase difference, and j is the imaginary part of symbol.

The power that calculates first group of antenna and second group of antenna described in the steps d adopts following formula: ${\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="C0310001900112.png,C0310001900121.png"\; state="\{\{state\}\}">P</figure-callout>}}_1=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&alpha;}}_k\right|}^2,$ ${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="C0310001900111.png,C0310001900112.png"\; state="\{\{state\}\}">P</figure-callout>}}_2=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&beta;}}_k\right|}^2,$ P wherein ₁Be the power of first group of antenna, P ₂Be the power of second group of antenna.

The weight of calculating first group of antenna and second group of antenna transmitting power in the step g adopts following formula:

$\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="w"\; filenames="C0310001900112.png,C0310001900121.png"\; state="\{\{state\}\}">w</figure-callout>}}_1=\frac{1}{\sqrt{1+{(\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&beta;}}_k\right|}^2/\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&alpha;}}_k\right|}^2)}^2}}=\frac{1}{\sqrt{1+{\left(\frac{1}{R}\right)}^2}}\\ {\mathrm{<figure-callout\; id="2"\; label="w"\; filenames="C0310001900111.png,C0310001900112.png"\; state="\{\{state\}\}">w</figure-callout>}}_2=\frac{1}{\sqrt{1+{(\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&alpha;}}_k\right|}^2/\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&beta;}}_k\right|}^2)}^2}}=\frac{1}{\sqrt{1+R^2}}\end{array}\right.$

Wherein, w ₁Be the weight of first group of antenna transmitting power, w ₂Be the weight of second group of antenna transmitting power, R is a power ratio.

Transmit diversity device comprises during a kind of adaptive space: the Space Time Coding module that is positioned at the base station, two groups of antenna sets of forming by two antennas, decoder, be positioned at the channel estimation module of portable terminal, encoder, described Space Time Coding module is to encoding symbols to be launched, output signal sends to portable terminal by described antenna sets, described channel estimation module is estimated each footpath signal, described encoder calculates the power of two groups of antennas and is compared, output FBI bit, issue described decoder by up channel, decoder draws the weight of the transmitting power of two groups of antennas, and adjusts two groups of antenna transmitting powers.

Described decoder further comprises delay line module, power ratio generator, weight calculator, the FBI bit storage is to described delay line module, described power ratio generator obtains the FBI bit from described delay line module, recover described power ratio and issue described weight calculator, described weight calculator output antenna transmitting power weight.

Described delay line module comprises and is no less than 1 memory cell, is used to store the FBI bit of sending recently.

Adopt the present invention, owing to can obtain to be no less than 1 FBI bit in real time, therefore when not increasing processing delay, can improve quantified precision, adjusted the transmitting power of antenna sets adaptively, thus the performance of transmit diversity systems when improving adaptive space.

Description of drawings

The composition structural representation of Fig. 1 transmit diversity systems during for adaptive space of the present invention;

Fig. 2 differs schematic diagram for two groups of antennas of the present invention;

Fig. 3 produces flow chart for FBI bit of the present invention;

Fig. 4 is a FBI decoding device structural representation of the present invention;

Fig. 5 is the mapping relations schematic diagram of FBI bit and power ratio;

Fig. 6 is the diversity performance contrast schematic diagram of the present invention and open loop STTD.

Embodiment

Describe specific implementation of the present invention in detail below in conjunction with accompanying drawing.

Closed loop transmit diversity scheme when Figure 1 shows that adaptive space of the present invention.At first armed symbol carries out Space Time Coding by Space Time Coding module 101 according to following rule, and incoming symbol is according to per 2 symbol (S ₁, S ₂) encode for cell block, the output two paths of signals: the one tunnel keeps identical (S with input block ₁, S ₂), the backward that grip altogether for input on another road, and first output symbol negate, i.e. output (S ₂ ^*, S ₁ ^*).Deliver to two groups of antennas after this two-way output is amplified respectively, wherein antenna Aa and Ab constitute first group of antenna, and antenna Ac and Ad constitute second group of antenna.Amplification factor and be 1 according to existing standard; In first group of antenna, differing by existing standard between antenna Aa and the Ab is defined as π, and each phase difference keeps two symbols at least; In second group of antenna, also differing between antenna Ac and the Ad is defined as π by existing standard equally, and each phase difference retention time is with identical with first group of antenna, as shown in Figure 2.

In the receiver of portable terminal, the respective feedback signal generates as follows and produces: at first pass through 102 couples of each multipath signal h from each antenna of channel estimation module _1k, h _2k, h _3kAnd h _4kEstimate, and calculate two " compound " channel response according to following formula:

$\left\{\begin{array}{c}\mathrm{\&alpha;}=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\mathrm{\&alpha;}}_k=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}(h_{1k}+h_{2k}{e}^{\mathrm{j\&phi;}})\\ \mathrm{\&beta;}=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_k=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}(h_{3k}+h_{4k}{e}^{\mathrm{j\&psi;}})\end{array}\right.$

This two each footpath complex response inputs in the FBI encoder 103, carries out cataloged procedure as shown in Figure 3: the received power that calculates compound channel 1 at first respectively ${\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="C0310001900112.png,C0310001900121.png"\; state="\{\{state\}\}">P</figure-callout>}}_1=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&alpha;}}_k\right|}^2$ And the received power of compound channel 2 ${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="C0310001900111.png,C0310001900112.png"\; state="\{\{state\}\}">P</figure-callout>}}_2=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&beta;}}_k\right|}^2,$ If the power P of compound channel 1 ₁Power P greater than compound channel 2 ₂, exporting the FBI bit so is 1, otherwise output FBI bit is 0.The every time slot of this process carries out once.The FBI bit is delivered to the base station after transmitting through up channel, is collected and is handled by the base station, determines the transmitting power weight of each antenna in view of the above.

The FBI bit that the base station receives is handled by FBI decoder 104, and Fig. 4 has represented FBI bit decode procedure: after the base station receives the FBI bit, nearest some FBI bits are stored in the delay line 105, wherein L represents the length of delay line; According to the up-to-date FBI bit in L position, recover power ratio R by power ratio generator 106, Fig. 5 has provided L=1,2, the 3 o'clock FBI bits mapping relations to power ratio R respectively; And this power ratio R delivered in the weight calculator 107, after weight calculator 107 receives power ratio R, calculate the weight w of two transmission antennas transmit power according to following formula 1 ₁And w ₂:

$\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="w"\; filenames="C0310001900112.png,C0310001900121.png"\; state="\{\{state\}\}">w</figure-callout>}}_1=\frac{1}{\sqrt{1+{(\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&beta;}}_k\right|}^2/\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&alpha;}}_k\right|}^2)}^2}}=\frac{1}{\sqrt{1+{\left(\frac{1}{R}\right)}^2}}\\ {\mathrm{<figure-callout\; id="2"\; label="w"\; filenames="C0310001900111.png,C0310001900112.png"\; state="\{\{state\}\}">w</figure-callout>}}_2=\frac{1}{\sqrt{1+{(\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&alpha;}}_k\right|}^2/\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&beta;}}_k\right|}^2)}^2}}=\frac{1}{\sqrt{1+R^2}}\end{array}\right.$

And according to w ₁And w ₂Adjust two groups of transmission antennas transmit power.

Adopted the present invention, kept under the prerequisite of compatibility with existing protocol, according to the information of the relevant current wireless channel that feeds back to, self adaptation is adjusted the transmitting power of two groups of transmitting antennas, compares with open loop approach, and diversity gain is bigger.Fig. 6 provided after the machine simulation as calculated the present invention and four antenna open loop STTD emission diversity performances relatively, as can be seen, the ASTTD performance under friction speed behind application the present invention is better than existing open loop STTD emission diversity performance.

The above only is the preferable specific implementation of the present invention, is not to be used to limit protection scope of the present invention.

Claims (9)

1, Closed-Loop Transmit Diversity method during a kind of adaptive space is characterized in that may further comprise the steps at least:

In each time slot,

A, base station are carried out armed symbol Space Time Coding and are exported two paths of signals;

After amplifying respectively, b, two paths of signals deliver to two groups of antennas, every group of antenna is made up of two antennas, between two antennas in first group of antenna, and with fixing differing two paths of signals is sent to portable terminal between two antennas in second group of antenna, and two groups of antennas to differ the retention time identical;

C, portable terminal are estimated each the footpath signal from each root antenna, obtain the compound channel response of corresponding two groups of antennas respectively;

D, according to the compound channel RESPONSE CALCULATION go out first group of antenna and second group of antenna power and compared, if the power of first group of antenna greater than the power of second group of antenna, then feedback signal FBI bit is 1, otherwise is 0;

E, FBI bit transfer to the base station by up channel, and what the base station will be received recently is no less than 1 FBI bit storage in delay line;

F, according to the mapping relations of predetermined FBI bit and power ratio, the FBI bit in the delay line is reverted to power ratio;

G, calculate the weight of first group of antenna and second group of antenna transmitting power, and adjust the transmitting power of two antennas according to power ratio.

2, Closed-Loop Transmit Diversity method during adaptive space as claimed in claim 1, it is characterized in that step a further comprises: symbol to be launched is that cell block is encoded according to per two symbols, the output two paths of signals, one the tunnel is identical with incoming symbol, and another road is backward and first symbol negate of incoming symbol conjugation.

3, Closed-Loop Transmit Diversity method during adaptive space as claimed in claim 1, it is characterized in that: it all is 1 that two groups of signals described in the step b amplify the amplification factor that adopts.

4, Closed-Loop Transmit Diversity method during adaptive space as claimed in claim 1, it is characterized in that: fixed phase difference described in the step b is π.

5, Closed-Loop Transmit Diversity method during adaptive space as claimed in claim 1 is characterized in that: obtain the compound channel response of corresponding two groups of antennas respectively described in the step c and adopt following formula:

$\left\{\begin{array}{c}\mathrm{\&alpha;}=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\mathrm{\&alpha;}}_k=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}(h_{1k}+h_{2k}{e}^{\mathrm{j\&phi;}})\\ \mathrm{\&beta;}=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_k=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}(h_{3k}+h_{4k}{e}^{\mathrm{j\&psi;}})\end{array}\right.,$

Wherein α is the compound channel response of corresponding first group of antenna, and β is the compound channel response of corresponding second group of antenna, and K is the footpath number of wireless channel transmission, h _1kAnd h _2kBe each footpath radio channel response of first group of antenna, h _3kAnd h _4kBe each footpath radio channel response of second group of antenna, φ and ψ are fixed phase difference, and j is the imaginary part of symbol.

6, Closed-Loop Transmit Diversity method during adaptive space as claimed in claim 1, it is characterized in that: the power that calculates first group of antenna and second group of antenna described in the steps d adopts following formula: $P_1=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&alpha;}}_k\right|}^2,$ $P_2=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&beta;}}_k\right|}^2,$ P wherein ₁Be the power of first group of antenna, P ₂Be the power of second group of antenna, α _kBe the compound channel response of corresponding first group of antenna, β _kBe the compound channel response of corresponding second group of antenna, K is the footpath number of wireless channel transmission.

7, Closed-Loop Transmit Diversity method during adaptive space as claimed in claim 1, it is characterized in that: the weight of calculating first group of antenna and second group of antenna transmitting power in the step g adopts following formula:

$\left\{\begin{array}{c}{w}_1=\frac{1}{\sqrt{1+{(\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&beta;}}_k\right|}^2/\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&alpha;}}_k\right|}^2)}^2}}=\frac{1}{\sqrt{1+{\left(\frac{1}{R}\right)}^2}}\\ w_2=\frac{1}{\sqrt{1+{(\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&alpha;}}_k\right|}^2/\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&beta;}}_k\right|}^2)}^2}}=\frac{1}{\sqrt{1+R^2}}\end{array}\right.$

Wherein, w ₁Be the weight of first group of antenna transmitting power, w ₂Be the weight of second group of antenna transmitting power, R is a power ratio, α _kBe the compound channel response of corresponding first group of antenna, β _kBe the compound channel response of corresponding second group of antenna, K is the footpath number of wireless channel transmission.

8, transmit diversity device during a kind of adaptive space, it is characterized in that comprising: the Space Time Coding module that is positioned at the base station, two groups of antenna sets of forming by two antennas, decoder, be positioned at the channel estimation module of portable terminal, encoder, described Space Time Coding module is to encoding symbols to be launched, output signal sends to portable terminal by described antenna sets, described channel estimation module is estimated each footpath signal, described encoder calculates the power of two groups of antennas and is compared, output FBI bit, issue described decoder by up channel, described decoder comprises delay line module, the power ratio generator, weight calculator, the FBI bit storage is to described delay line module, described power ratio generator obtains the FBI bit from described delay line module, recover described power ratio and issue described weight calculator, described weight calculator calculates the weight of the transmitting power of two groups of antennas, and adjusts two groups of antenna transmitting powers.

9, transmit diversity device during adaptive space as claimed in claim 8 is characterized in that: described delay line module comprises and is no less than 1 memory cell, is used to store the FBI bit of sending recently.

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