CN100454795C - An Adaptive Space-Time Closed-Loop Transmit Diversity Method and System - Google Patents

Abstract

The invention discloses an adaptive space-time closed-loop transmit diversity method and system thereof. In each time slot, symbols to be transmitted are space-time coded and output two-way signals; they are respectively amplified and sent to two groups of antennas, and the two signals are sent to two groups of antennas. The mobile terminal estimates the signals of each path from each antenna, calculates and compares the power of the first group of antennas and the second group of antennas, and obtains FBI bits, which are transmitted to the base station through the uplink channel. The base station will Store the FBI bits in the delay line; restore the FBI bits in the delay line to the success rate ratio; calculate the weight of the transmission power of the first group of antennas and the second group of antennas according to the power ratio, and adjust the transmission power of the two antennas. By adopting the invention, the transmitting power of two groups of transmitting antennas can be adaptively adjusted, and the diversity gain is larger compared with the open-loop mode.

Description

An Adaptive Space-Time Closed-Loop Transmit Diversity Method and System

technical field

The present invention relates to a space-time transmission diversity technology, in particular to a space-time transmission diversity method and a device thereof which adjust signal transmission power in an adaptive manner in real time.

Background technique

In the wideband CDMA (WCDMA, Wideband CDMA) system of the third generation (3G, Third Generation) mobile communication system based on Code Division Multiple Access (CDMA), due to different users in the same cell and adjacent cells Different users share the same frequency band at the same time, so there is interference between users, which limits the system capacity and information transmission rate. In order to improve system capacity, can adopt many kinds of diversity methods, such as multipath diversity, space diversity and antenna diversity and other technologies. In a system using diversity technology, there are multiple independent copies of the same information content in different forms. After these independent copies are received by the receiver, according to the principle of maximum likelihood (MaximumLikelihood, ML), the redundant characteristics of information are fully utilized. With certain special treatment, the bit error rate of transmitted information can be greatly reduced, and the energy required for wireless data transmission can be reduced, thereby reducing mutual interference between users. It can be seen that the diversity technology can effectively improve the system capacity.

The development of semiconductor technology makes it possible to transmit diversity with more than two antennas; as the number of transmit antennas increases, the diversity gain obtained is greater. In the existing CDMA standard, the four-antenna transmit diversity mainly includes the open-loop space-time transmit diversity method (Open-loop STTD). In this transmit diversity method, due to the lack of information on the current wireless channel, the two transmit antennas always Transmitting in the mode of equal power cannot make adaptive adjustment to the time-varying wireless channel, so there is a certain performance loss.

Contents of the invention

In order to solve the above problems, the purpose of the present invention is to propose an adaptive space-time closed-loop transmit diversity method, which can adaptively adjust the transmit power of two sets of transmit antennas and improve the diversity gain.

Another object of the present invention is to propose a system for implementing the above adaptive space-time closed-loop transmit diversity method.

To achieve the above object, the technical scheme of the present invention is as follows:

An adaptive space-time closed-loop transmit diversity method at least includes the following steps:

In each time slot,

a. The base station performs space-time coding on the symbols to be transmitted and outputs two signals;

b. The two signals are respectively amplified and then sent to two sets of antennas. Each set of antennas is composed of two antennas. The phase difference sends the two signals to the mobile terminal, and the difference between the two sets of antennas keeps the same time;

c. The mobile terminal estimates the signals of each path from each antenna, and obtains composite channel responses corresponding to two groups of antennas;

d. Calculate the power of the first group of antennas and the second group of antennas according to the composite channel response and compare them. If the power of the first group of antennas is greater than the power of the second group of antennas, the feedback signal (FeedBackIndication, FBI) bit is 1, otherwise 0;

e. The FBI bit is transmitted to the base station through the uplink channel, and the base station stores no less than one FBI bit recently received in the delay line;

f. According to the predetermined mapping relationship between the FBI bit and the power ratio, restore the FBI bit in the delay line to the success rate ratio;

g. Calculate the weights of the transmit power of the first group of antennas and the second group of antennas according to the power ratio, and adjust the transmit power of the two antennas.

Step a further includes: code the symbols to be transmitted according to every two symbols as a unit block, and output two signals, one of which is the same as the input symbol, and the other is the reverse order of the conjugate of the input symbol and the first symbol is reversed.

In step b, the amplification factors used for the amplification of the two groups of signals are both 1; the fixed phase difference is π.

The following formula is used to obtain the composite channel responses respectively corresponding to two groups of antennas described in step c:

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j\&phi;</span>}}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j\&psi;</span>}}<span\; class="notranslate">\; )</span>\end{array}\right.<span\; class="notranslate">\; ,</span>$

Where α is the composite channel response corresponding to the first group of antennas, β is the composite channel response corresponding to the second group of antennas, K is the number of paths transmitted by the wireless channel, h _1k and h _2k are the wireless channel responses of each path of the first group of antennas, h _3k and h _4k are the wireless channel responses of the second group of antennas, φ and ψ are fixed phase differences, and j is the symbol of the imaginary part.

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

In step g, the weights for calculating the transmission power of the first group of antennas and the second group of antennas adopt the following formula:

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

Wherein, w ₁ is the weight of the transmit power of the first group of antennas, w ₂ is the weight of the transmit power of the second group of antennas, and R is the power ratio.

An adaptive space-time closed-loop transmit diversity system includes: a space-time coding module located at a base station, two sets of antenna groups consisting of two antennas, a decoder, a channel estimation module and an encoder located at a mobile terminal, and the space-time coding module The module encodes the symbol to be transmitted, the output signal is sent to the mobile terminal through the antenna group, the channel estimation module estimates the signals of each path, the encoder calculates the power of the two groups of antennas and compares them, and outputs FBI bits, through The uplink channel is sent to the decoder, and the decoder obtains the weights of the transmission powers of the two groups of antennas, and adjusts the transmission powers of the two groups of antennas.

The decoder further includes a delay line module, a power ratio generator, and a weight calculator, and the FBI bits are stored in the delay line module, and the power ratio generator obtains the FBI bits from the delay line module to recover the power The ratio is sent to the weight calculator, and the weight calculator outputs the antenna transmit power weight.

The delay line module includes no less than one storage unit for storing the latest FBI bits.

Adopting the present invention, since no less than 1 FBI bit can be obtained in real time, the quantization accuracy can be improved without increasing the processing delay, and the transmit power of the antenna group can be adaptively adjusted, thereby improving the adaptive space-time transmit diversity system performance.

Description of drawings

FIG. 1 is a schematic diagram of the composition structure of the adaptive space-time transmit diversity system of the present invention;

Fig. 2 is a schematic diagram of the phase difference between two groups of antennas of the present invention;

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

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

Fig. 5 is a schematic diagram of the mapping relationship between FBI bit and power ratio;

FIG. 6 is a schematic diagram of diversity performance comparison between the present invention and an open-loop STTD.

Detailed ways

The specific implementation of the present invention will be described in detail below in conjunction with the accompanying drawings.

FIG. 1 shows the adaptive space-time closed-loop transmit diversity scheme of the present invention. First, the symbols to be transmitted are space-time coded by the space-time coding module 101 according to the following rules, and the input symbols are coded according to every 2 symbols (S ₁ , S ₂ ) as a unit block, and two signals are output: one path remains the same as the input block (S ₁ , S ₂ ), the other way is the reverse order of the input conjugate, and the first output sign is reversed, that is, output (-S ₂ ^* , S ₁ ^* ). The two outputs are respectively amplified and sent to two sets of antennas, wherein the antennas Aa and Ab form the first set of antennas, and the antennas Ac and Ad form the second set of antennas. The amplification factor and according to the existing standard are both 1; in the first group of antennas, the phase difference between the antennas Aa and Ab is determined by the existing standard to be π, and each phase difference value maintains at least two symbols; also in the second group Among the antennas, the phase difference between the antennas Ac and Ad is also determined as π by the existing standard, and the holding time of each phase difference value is the same as that of the first group of antennas, as shown in FIG. 2 .

In the receiver of the mobile terminal, the corresponding feedback signal is generated according to the following method: first, the channel estimation module 102 estimates the multipath signals h _1k , h _2k , h _3k and h _4k from each antenna, and according to the following formula Compute two "composite" channel responses:

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j\&phi;</span>}}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j\&psi;</span>}}<span\; class="notranslate">\; )</span>\end{array}\right.$

The composite responses of the two paths are input into the FBI encoder 103, and the encoding process shown in Figure 3 is carried out: firstly, the received power of the composite channel 1 is calculated 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 composite 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 ₁ of the composite channel 1 is greater than the power P ₂ of the composite channel 2, the output FBI bit is 1, otherwise the output FBI bit is 0. This process is performed every time slot. After the FBI bits are transmitted through the uplink channel, they are sent to the base station, and the base station collects and processes them to determine the transmit power weight of each antenna.

The FBI bits received by the base station are processed by the FBI decoder 104. FIG. 4 shows the FBI bit decoding process: after the base station receives the FBI bits, the latest FBI bits are stored in the delay line 105, where L represents the length of the delay line; According to the latest FBI bit of the L position, the power ratio R is recovered by the power ratio generator 106, and Fig. 5 has respectively provided the mapping relation of the FBI bit to the power ratio R when L=1, 2, and 3; and the power ratio R Send it to the weight calculator 107. After the weight calculator 107 receives the power ratio R, it calculates the weights w ₁ and w ₂ of the transmit power of the two transmit antennas according to the following formula 1:

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

And according to w ₁ and w ₂ , adjust the transmission power of the two groups of transmitting antennas.

Adopting the present invention, on the premise of maintaining compatibility with the existing protocol, adaptively adjusts the transmitting power of two sets of transmitting antennas according to the feedback information about the current wireless channel, and has greater diversity gain compared with the open-loop method. Fig. 6 has provided the present invention and four antenna open-loop STTD transmit diversity performance comparisons after computer simulation, can find out, the ASTTD performance after applying the present invention is better than existing open-loop STTD transmit diversity performance at different speeds.

The above descriptions are only preferred specific implementation modes of the present invention, and are not intended to limit the protection scope of the present invention.

Claims (9)

1. An adaptive space-time closed-loop transmit diversity method, characterized in that it at least comprises the following steps: In each time slot, a. The base station performs space-time coding on the symbols to be transmitted and outputs two signals; b. The two signals are respectively amplified and then sent to two sets of antennas. Each set of antennas is composed of two antennas. The phase difference sends the two signals to the mobile terminal, and the difference between the two sets of antennas keeps the same time; c. The mobile terminal estimates the signals of each path from each antenna, and obtains composite channel responses corresponding to two groups of antennas; d. Calculate and compare the power of the first group of antennas and the second group of antennas according to the composite channel response. If the power of the first group of antennas is greater than the power of the second group of antennas, the feedback signal FBI bit is 1, otherwise it is 0; e. The FBI bit is transmitted to the base station through the uplink channel, and the base station stores no less than one FBI bit recently received in the delay line; f. According to the predetermined mapping relationship between the FBI bit and the power ratio, restore the FBI bit in the delay line to the success rate ratio; g. Calculate the weights of the transmit power of the first group of antennas and the second group of antennas according to the power ratio, and adjust the transmit power of the two antennas. 2. The adaptive space-time closed-loop transmit diversity method as claimed in claim 1, wherein step a further comprises: the symbols to be transmitted are coded according to every two symbols as a unit block, and output two signals, one of which is the same as the input symbol , and the other way is the reverse order of the conjugate of the input symbols and the first symbol is reversed. 3. The adaptive space-time closed-loop transmit diversity method according to claim 1, characterized in that: in step b, the amplification factors used for amplifying the two groups of signals are both 1. 4. The adaptive space-time closed-loop transmit diversity method according to claim 1, wherein the fixed phase difference in step b is π. 5. The adaptive space-time closed-loop transmit diversity method as claimed in claim 1, characterized in that: the composite channel response corresponding to two groups of antennas obtained in step c adopts the following formula: $\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j\&phi;</span>}}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j\&psi;</span>}}<span\; class="notranslate">\; )</span>\end{array}\right.<span\; class="notranslate">\; ,</span>$ Where α is the composite channel response corresponding to the first group of antennas, β is the composite channel response corresponding to the second group of antennas, K is the number of paths transmitted by the wireless channel, h _1k and h _2k are the wireless channel responses of each path of the first group of antennas, h _3k and h _4k are the wireless channel responses of the second group of antennas, φ and ψ are fixed phase differences, and j is the symbol of the imaginary part. 6. The adaptive space-time closed-loop transmit diversity method as claimed in claim 1, characterized in that: the calculation of the power of the first group of antennas and the second group of antennas in step d adopts the following formula: $P_1=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&alpha;}}_k\right|}^2,$ $P_2=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\left|{\mathrm{\&beta;}}_k\right|}^2,$ Where P ₁ is the power of the first group of antennas, P ₂ is the power of the second group of antennas, α _k is the composite channel response corresponding to the first group of antennas, β _k is the composite channel response corresponding to the second group of antennas, and K is the wireless The number of paths transmitted by the channel. 7. The adaptive space-time closed-loop transmit diversity method as claimed in claim 1, characterized in that: in the step g, the weights for calculating the transmission power of the first group of antennas and the second group of antennas adopt the following formula: $\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; /</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}\\ {\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; /</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}\end{array}\right.$ Among them, w ₁ is the weight of the transmission power of the first group of antennas, w ₂ is the weight of the transmission power of the second group of antennas, R is the power ratio, α _k is the composite channel response corresponding to the first group of antennas, and β _k is the weight of the second group of antennas. The composite channel response of the antenna group, K is the number of paths transmitted by the wireless channel. 8. An adaptive space-time closed-loop transmit diversity system, characterized in that it comprises: a space-time encoding module located at the base station, two groups of antenna groups composed of two antennas, a decoder, a channel estimation module located at the mobile terminal, and an encoder , the space-time encoding module encodes the symbol to be transmitted, the output signal is sent to the mobile terminal through the antenna group, the channel estimation module estimates the signals of each path, and the encoder calculates the power of the two groups of antennas and compares them , output FBI bit, send to described decoder through uplink channel, described decoder comprises delay line module, power ratio generator, weight calculator, FBI bit is stored in described delay line module, and described power ratio generator is from The delay line module obtains FBI bits, restores the power ratio and sends it to the weight calculator, and the weight calculator calculates the weight of the transmission power of the two groups of antennas, and adjusts the transmission power of the two groups of antennas. 9. The adaptive space-time closed-loop transmit diversity system according to claim 8, wherein the delay line module includes no less than one storage unit for storing the latest FBI bits.

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