CN1266856C - Signal transmitting and receiving method based on time-division duplex in radio communication system - Google Patents

Abstract

The invention discloses a signal transmitting and receiving method based on time-division duplexing in a wireless communication system. The method is based on the principle that the noises received by each antenna are independent of each other on the base station side and the mobile station side or that signals from different transmitting antennas arrive at different receivers. Multiple antennas are set up separately on the principle that the channels of the antennas are independent of each other; all antennas of the base station transmit pilot signals within a fixed time period assigned; the mobile station measures all received pilot signals on its own different receiving antennas, and selects the One or more antennas are used as uplink transmitting antennas to transmit signals; at the same time, according to the received pilot signal, one or more antennas of the base station are selected as transmitting antennas and notified to the base station. The selected antenna transmits a signal to the mobile station during the downlink transmission time period. The above solution can improve the transmission efficiency of high-speed data, and obtain the highest possible signal-to-interference (noise) ratio at the signal receiving end.

Description

Signal Transmitting and Receiving Method Based on Time Division Duplex in Wireless Communication System

technical field

The present invention relates to signal transmission and reception methods in a wireless communication system.

Background technique

Wireless communication provides the means for people to connect with each other and obtain information anytime and anywhere, so it has been rapidly popularized in recent years. However, in the current wireless environment, due to the requirement of mobility, the directional transmission of wireless signals has certain limitations, which inevitably causes mutual interference between wireless communications of different users. In order to ensure the normal progress of various wireless communications, the use of wireless spectrum is generally subject to strict restrictions and management. In this way, wireless communication cannot have a large bandwidth like wired communication. Therefore, based on the limited available wireless spectrum, how can Increasing the information transmission capability of the wireless communication system is an urgent problem to be solved.

In wireless communication, the fading wireless channel is one of the main factors hindering the realization of effective communication. To this end, the researchers proposed a multi-antenna transmission/reception technology, "In a fading environment, a wireless communication multi-layer space-time structure using multiple antennas (G J Foschini, "Layered space-time architecture for wire1ess communication in fading environment when using multi -element antennas ", Bell Labs Technical Journal, pp.41-59, Autumn1996.) the above-mentioned technology is disclosed in the article, which can ensure high-efficiency high-speed data transmission communication under the assumption of an independent flat fading channel. However, Since the multiple channels of wireless reception cannot be kept independent of each other at any time, there is still a large interference between each other in each receiving unit time, coupled with factors such as mutual coupling of antennas, the method of simultaneous transmission/reception of multiple antennas is being realized. There is still the problem that the efficiency is seriously reduced.Recent research on multi-antenna systems has begun to consider how to select the transmit antenna based on feedback, such as "Optimal Antenna Selection for Multiple-Input Multiple-Output Systems Using Space-Time Block Coding" (A Paulraj and D Gore, "Optimal antenna selection in MIMO systems with space-time block coding", IEICE Trans.Commun., 2001(E84-B): 7, pp.1713-1719.) published similar research results .However, there must be time delay in any feedback, and the existence of time delay will definitely affect the efficiency of the system.

Contents of the invention

The purpose of the present invention is to provide a signal transmission and reception method based on time division duplex in a wireless communication system, using this method can improve the transmission efficiency of high-speed data, and obtain the highest possible signal-to-interference (noise) ratio at the signal receiving end .

In order to achieve the above object, the signal transmission and reception method based on time division duplexing in the wireless communication system provided by the present invention comprises the following steps:

Step 1: Set up multiple antennas on the base station side and the mobile station side respectively, and the multiple antennas are set according to the principle that the noise received by each antenna is independent of each other or according to the principle that the signals of different transmitting antennas arrive at different channels of different receiving antennas. set up;

Step 2: All antennas of the base station transmit pilot signals within a fixedly allocated time period;

Step 3: The mobile station measures all received pilot signals on its different receiving antennas, selects one or more antennas as the uplink transmitting antenna, and uses the selected antenna as the transmitting antenna from the next uplink transmitting moment. The antenna transmits signals during the uplink transmission time period;

Step 4: The mobile station selects one or more antennas of the base station as transmitting antennas according to all received pilot signals on its own different receiving antennas, and notifies the base station to use the antennas selected by the mobile station for the next downlink transmission transmit a signal to the mobile station;

Step 5: The base station uses multiple antennas to receive the signal of the mobile station, and according to the notification of the mobile station, selects one or more antennas as the downlink transmission antenna, and transmits signals to the mobile station within the downlink transmission time period from the next downlink transmission time. transmit a signal.

In step 2, all antennas of the base station transmit pilot signals in a code-division manner within a fixedly allocated time period.

The transmitting of the pilot signal according to the code division means that all the antennas of the base station select codes obtained by using the same code through different cyclic shifts as pilots within a fixedly allocated time period to transmit.

In step 2, all antennas of the base station may also transmit pilot signals in a time-division manner within a fixedly allocated time period.

The one or more antennas selected in step 3 are the antennas with the largest sum of received transmitted signal strengths or signal-to-noise ratios.

The one or more antennas selected in step 4 are the antennas with the largest sum of received signal strengths or signal-to-noise ratios of transmitted signals on all antennas of the mobile station.

In step 5, when the channels of multiple antenna signals on the base station side are strongly correlated, select multiple antennas on the base station side to transmit the same signal at the same time, and implement directional transmission of downlink signals by applying different weights to different antennas.

A signal transmission and reception method based on time division duplexing in another wireless communication system provided by the present invention comprises the following steps:

Step 11: setting multiple antennas on the base station side and the mobile station side respectively, the multiple antennas are set according to the principle that the signals of different transmitting antennas reach the channels of different receiving antennas independently of each other;

Step 12: All antennas of the base station transmit pilot signals within a fixedly allocated time period;

Step 13: The mobile station measures all received pilot signals on its different receiving antennas, selects one or more antennas as the uplink transmitting antenna, and uses the selected antenna as the transmitting antenna from the next uplink transmitting moment. The antenna transmits signals during the uplink transmission time period;

Step 14: The mobile station selects one or more antennas of the base station as transmitting antennas according to all received pilot signals on its own different receiving antennas, and notifies the base station to use the above antennas selected by the mobile station for the next downlink transmission transmit a signal to the mobile station;

Step 15: The base station uses multiple antennas to receive the signal of the mobile station, and according to the notice of the mobile station, selects one or more antennas as the downlink transmission antenna, and transmits the signal to the mobile station within the downlink transmission time period from the next downlink transmission time. transmit a signal.

Compared with the existing multi-antenna transmission/reception method, the present invention can be applied under the condition that multiple signal channels are independent of each other, and can also be applied under the condition that only the noise signals of different antennas are required to be independent of each other, so it can be used in a practical environment It is more extensive and can be applied in diversity antennas and smart antennas; in addition, the present invention utilizes the broadcast of the multi-antenna common pilot signal of the base station, so that the mobile station can simultaneously estimate the distance between the multi-antenna of the base station and its own multi-antenna. According to this, in the time division duplex system, the mobile station can obtain the channel conditions of uplink and downlink at the same time, so as to select the optimal uplink transmit antenna according to a certain principle, which can be one or multiple transmit antennas. While transmitting data uplink, notify the base station of the transmit antenna that should be selected when transmitting data for the mobile station next time, so as to obtain the optimal performance of uplink and downlink multi-antenna transmission and reception at the same time; therefore, using this method can improve the transmission efficiency of high-speed data , and obtain the highest possible signal-to-interference (noise) ratio at the signal receiving end.

Description of drawings

Fig. 1 is an example diagram of a multi-antenna time-division duplex system applying the present invention;

FIG. 2 is a schematic diagram of allocation of uplink and downlink transmission periods.

Detailed ways

In existing multi-antenna systems, the premise of its application is the existence of independent Rayleigh fading channels. The key to the realization of the multi-antenna system lies in the commercialization of the multi-antenna at the mobile station. The difficulty lies in the contradiction between the portability of the equipment and the independence of the multi-antenna channels. Due to the diversity of the actual environment, when the distance between the receiving antennas of the mobile station is half of the carrier wavelength, there may still be a large correlation between the fading channels experienced by the signal, which makes it difficult to set up the antennas of the mobile station. However, for noise, since the incoming azimuth angle distribution of the noise signal is relatively wide, and the noise itself is also a combination of multiple signals, it is better to realize the independent reception noise of multiple antennas on the mobile station than to ensure that the signals on different antennas are independent of each other. It is easier to realize that the channels are independent of each other.

Taking two receiving antennas as an example, when the noise received by them is independent of each other, for the transmitting signal of a single transmitting antenna, the received signal on the two receiving antennas can be expressed by the following expression:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, r ₁ and r ₂ are the received signals on antenna 1 and antenna 2 respectively, S is the symbol transmitted by a single antenna, assuming that the symbol energy is E _s , h ₁ and h ₂ are respectively when the symbol reaches two receiving antennas The experienced fading channel, n ₁ and n ₂ is the noise received by the two antennas.

According to the existing methods for transmitting and receiving wireless signals with multiple antennas, it is assumed that h ₁ and h ₂ are known (or estimated) flat fading channels, and they are constant or slowly changing in a short time of signal reception (here It is not required that the two channels are mutually independent), and it is assumed that the noises n ₁ and n ₂ received by the two antennas are Gaussian noise, and the noise power is σ ² . As can be seen from the previous discussion, it is easy to ensure that the two noise signals are independent of each other in implementation. For example, when the two antennas are separated by more than half of the carrier wavelength, the two noise signals are independent of each other. The maximum ratio combination is performed on the received signals of the antenna, then the combined signal:

$\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; *</span>}{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; *</span>}{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; *</span>}{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; *</span>}{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

The resulting signal-to-noise ratio is:

$\mathrm{<span\; class="notranslate">\; SNR</span>}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}}{{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</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">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}}{{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

则由公式(3)可知，接收信号的信噪比得到了增强。由于信噪比的增强不需要信号信道独立的条件，而只需要噪声相互独立的条件；这一条件，在无线环境中容易得到满足，例如，在设置多天线时，只要不同天线相距超过载波波长的一半即可基本得到满足，无论是在基站侧，还是在移动终端侧。The original signal-to-noise ratios of the two receiving antennas are

It can be seen from formula (3) that the signal-to-noise ratio of the received signal is enhanced. Since the enhancement of signal-to-noise ratio does not require the independent condition of the signal channel, but only the independent condition of the noise; this condition is easy to be satisfied in the wireless environment, for example, when setting up multiple antennas, as long as the distance between different antennas exceeds the carrier wavelength Half of can be basically satisfied, whether it is on the base station side or on the mobile terminal side.

Since the uplink and downlink use the same carrier in the time division duplex system, channel estimates on both sides can be obtained simultaneously through single-side channel measurement. This enables the multi-antenna system to simplify the feedback of channel measurement when it is applied in the time division duplex system, which is beneficial to improve the performance of the multi-antenna transmission/reception method.

Different from the base station broadcasting the pilot signal, in a wireless communication cell, it is impossible for the mobile user to send the pilot signal to the base station at any time for the base station to measure the channel condition of the user. This point is especially prominent when realizing multi-antenna transmission/reception. Suppose there are 3 users in a cell, and each user's mobile device has two transmit antennas. In order for the base station to obtain an effective estimate of the transmission channel conditions of all antennas of these user equipments, it is necessary to allocate 3×2=6 resources for these users, which means that 6 codes need to be allocated in a code division multiple access system, and in time division multiple access In the system, it means that 6 sufficiently long time slots need to be allocated, and the number of allocated resources increases linearly with the increase of the number of users. Therefore, in a general time-division duplex wireless communication system, only the method of broadcasting pilot signals by the base station, that is, the common pilot signal, can be used to enable the mobile station to obtain uplink and downlink channel estimates through measurement.

In the multi-antenna transmission/reception system that selects the transmission antenna, the application of the above-mentioned one-way common pilot signal transmission method will make the signal transmission in a certain direction lack the basis for judgment because the channel estimation of all antennas is not available. The performance of the method is thus partially lost, so the above-mentioned disadvantages must be avoided in a multi-antenna transmission/reception system.

The implementation of the present invention will be further described in detail below.

对于上述天线的设置，也可以做进一步的要求，使得不同天线上接收到的各个信号所经历的信道都是相互独立的，即，上述多个天线按照不同发射天线的信号到达不同接收天线的信道相互独立的原则设置。In a wireless communication system based on time division duplexing, firstly, multiple antennas are set up on the base station side and the mobile station side respectively, and the above multiple antennas are set up according to the principle that the noise received by each antenna is independent of each other. Specifically, the following methods can be used to set up: base station The distance between the antennas on the side can be determined according to the size of the sector angle α of the service, so that the distance between two adjacent antennas is not less than the half-wavelength of the carrier × 360 degrees/a, that is, the distance between adjacent antennas is greater than or equal to It can also be simply set to half of the carrier wavelength; the distance between adjacent antennas on the mobile station side should not be less than half of the carrier wavelength, that is, the distance between adjacent antennas is greater than or equal to

For the above-mentioned antenna setting, further requirements can also be made so that the channels experienced by the signals received on different antennas are independent of each other, that is, the above-mentioned multiple antennas reach the channels of different receiving antennas according to the signals of different transmitting antennas The principles set independently of each other.

In the time division duplex system, a separate time slot is arranged in the downlink transmission time period for all transmitting antennas of the base station to transmit common pilots. The transmission mode of the pilot signals of different antennas can be code division or time division. If the code division method is adopted, all antennas of the base station can also select codes obtained by the same code through different cyclic shifts as pilots for transmission within a fixedly allocated time period. For example, assuming there is a code sequence [m ₁ m ₂ ...m ₁₂₈ ], the pilot sequence [m ₁ ...m ₁₂₈ m ₁ ...m ₈ ] can be assigned to the base station antenna 1, and the pilot sequence [m ₉ …m ₁₂₈ m ₁ …m ₁₆ ], and so on. All codes obtained by cyclically shifting one code have better properties, that is, channel estimation is extremely simple, as long as the same sequence is multiplied by multiple cycles, all channel estimates can be obtained. When the multi-antenna common pilot is transmitted, the use of this code is very helpful for simplifying the channel estimation of the mobile station. The mobile stations measure the channels on their respective multi-antennas by themselves according to the common pilot signal broadcast by the base station, and obtain all channel estimates between the respective mobile station antennas and the base station antennas. On the basis of this channel estimation, the mobile station determines the antenna for uplink transmission according to a certain criterion. It can be one transmitting antenna or multiple transmitting antennas. Using the determined uplink transmitting antenna, the mobile station transmits data uplink within the uplink transmission time period from the next uplink transmission moment. The selection of one or more antennas mentioned here refers to selecting the antenna with the largest sum of received transmitted signal strengths or signal-to-noise ratios. At the same time, the mobile station also selects one or more antennas of the base station as transmitting antennas according to all received pilot signals on its own different receiving antennas, and notifies the base station to use the antennas selected by the mobile station for the next downlink transmission. A signal is transmitted to the mobile station. The selection of one or more antennas mentioned here is to select the antenna with the largest received signal strength or signal-to-noise ratio of the transmitted signal on all mobile station antennas. After receiving the notification from the mobile station, the base station will automatically At a downlink transmission time, select the antenna selected by the mobile station to transmit data for the mobile station during the downlink transmission time period, and continue to broadcast the common pilot signal in the fixedly allocated time slice, providing the mobile station with channel estimation at the next moment .

The method of the present invention does not exclude the use of base station smart antennas. In the downlink transmission of the base station, if multiple antennas are fully correlated or strongly correlated, the multiple antennas can also be used to implement directional transmission. In directional transmission, the signals transmitted by multiple antennas are exactly the same, and the channels experienced are basically the same, the difference is only in the weight value, thus forming a spatial directional transmission, so its effect is still equivalent to single antenna transmission.

FIG. 1 is an example diagram of a multi-antenna time division duplex system applying the present invention. According to the illustration in the figure, the base station has 4 antennas, and the mobile station has 6 antennas. Fig. 2 is a schematic diagram of uplink and downlink transmission time allocation. Referring to Figure 2, if the time division duplex method is adopted, within a transmission period, it can be divided into uplink transmission period and downlink transmission period. The base station transmits common pilots within a certain fixed time of the downlink transmission period. During this time period , the base station does not transmit other data signals, and different transmitting antennas can use code division to transmit pilots spread with different codes, which is convenient for the mobile station to measure different channels.

According to the setting in Fig. 1, the four antennas of the base station transmit pilot signals of different codes in the common pilot time slice of the downlink transmission period. The six receiving antennas of the mobile station estimate different channels based on these pilot signals. There are a total of 24 channels here, expressed in the form of a matrix:

$\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; =</span>\left[\begin{array}{cccc}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 13</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 14</span>}}\\ {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; one</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; two</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; three</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; four</span>}}\\ {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 31</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 32</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 33</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 34</span>}}\\ {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 41</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 42</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 43</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 44</span>}}\\ {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 51</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 52</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 53</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 54</span>}}\\ {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 61</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 62</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 63</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 64</span>}}\end{array}\right]<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$

Among them, h _ij represents the channel through which the transmitted signal of the j-th base station antenna reaches the i-th mobile station antenna. Due to the use of time division duplexing, in the uplink transmission period in the next transmission cycle, the channel experienced by the transmission signal of the i-th mobile station antenna when it reaches the j-th base station antenna is roughly h _ij . Based on this phenomenon, the mobile station can select the antenna used for uplink transmission according to the channel estimation result in (4) during the uplink transmission period of the next transmission cycle. According to the channel conditions and the amount of data to be transmitted, select one transmitting antenna or multiple transmitting antennas. Assuming that the mobile station needs to select two transmitting antennas, the principle for the mobile station to select the antenna can be the principle that the sum of the received energy of all transmitting antenna signals on the antenna is the largest. In the channel expressed in (4), each row of the calculation matrix The sum of the squares of the amplitudes of the elements, ∑ _j |h _ij | ² , 1≤i≤6, select the antenna corresponding to i that makes this sum of squares the largest as the transmitting antenna. Assuming that the mobile station selects the first and third antennas to transmit signals to the base station, that is, in the above sum of squares calculation formula, i=1, 3, then the mobile station can send data to the two antennas for transmission. In addition, the mobile station also selects the transmit antenna that the base station should use for the next transmission according to the channel in (4). The selection principle can be the principle that the sum of the received signal energy of the transmit antenna on all the receive antennas of the mobile station is the largest. That is, the mobile station calculates the sum of the squares of the amplitudes of each element in each column of the matrix in (4), ∑ _i |h _ij | ² , 1≤j≤4, assuming that the formula obtains the maximum value when j=1, namely

|h ₁₁ | ² +|h ₂₁ | ² +|h ₃₁ | ² +|h ₄₁ | ² +|h ₅₁ | ² +|h ₆₁ | ²

maximum, the mobile station can notify the base station to use antenna 1 to transmit within the downlink transmission period. The base station uses four antennas to receive signals at the same time, and at the same time obtains from the mobile station which antenna or antennas should be used to transmit signals for the mobile station during the downlink transmission period of the transmission cycle. Through the cyclic execution of the above process, the high-speed data communication between the base station and the mobile station is finally realized.

In the above communication process, assuming that the mobile station has measured and learned that there is a strong correlation between the first antenna and the second antenna of the base station, and the directional transmission of the smart antenna can be realized, then when the base station learns from the mobile station that the downlink transmission period requires When one of the two antennas is used for signal transmission, two antennas can also be selected to transmit the same signal at the same time, and the downlink directional transmission can be realized through different weighting.

Claims (8)

1. A method for transmitting and receiving signals based on time division duplexing in a wireless communication system, comprising the steps of: Step 1: setting multiple antennas on the base station side and the mobile station side respectively, the multiple antennas are set according to the principle that the noise received by each antenna is independent of each other; Step 2: All antennas of the base station transmit pilot signals within a fixedly allocated time period; Step 3: The mobile station measures all received pilot signals on its different receiving antennas, selects one or more antennas as the uplink transmitting antenna, and uses the selected antenna as the transmitting antenna from the next uplink transmitting moment. The antenna transmits signals during the uplink transmission time period; Step 4: The mobile station selects one or more antennas of the base station as transmitting antennas according to all received pilot signals on its own different receiving antennas, and notifies the base station to use the antennas selected by the mobile station for the next downlink transmission transmit a signal to the mobile station; Step 5: The base station uses multiple antennas to receive the signal of the mobile station, and according to the notification of the mobile station, selects one or more antennas as the downlink transmission antenna, and transmits signals to the mobile station within the downlink transmission time period from the next downlink transmission time. transmit a signal. 2. The method for transmitting and receiving signals based on time division duplexing according to claim 1, characterized in that: in step 2, all antennas of the base station transmit pilot signals in a code-division manner within a fixedly allocated time period. 3. The method for transmitting and receiving signals based on time-division duplexing according to claim 2, characterized in that: said transmitting pilot signals in a code-division manner is that all antennas of the base station select the same antenna within a fixedly allocated time period. Codes obtained by different cyclic shifts are used as pilots for transmission. 4. The signal transmitting and receiving method based on time division duplexing according to claim 1, characterized in that: in step 2, all antennas of the base station transmit pilot signals in a time division manner within a fixedly allocated time period. 5. The method for transmitting and receiving signals based on time division duplexing according to claim 1, 2, 3 or 4, characterized in that one or more of the antennas selected in step 3 are the received The antenna with the largest sum of transmitted signal strength or signal-to-noise ratio. 6. The method for transmitting and receiving signals based on time division duplexing according to claim 5, characterized in that one or more antennas selected in step 4 are used to transmit signals on all mobile station antennas The antenna with the largest sum of received signal strength or signal-to-noise ratio. 7. The method for transmitting and receiving signals based on time division duplexing according to claim 6, characterized in that: in step 5, when the channels of multiple antenna signals on the base station side are strongly correlated, simultaneously select multiple antennas on the base station side The same signal is transmitted by the antenna, and the directional transmission of the downlink signal is realized by applying different weights to different antennas. 8. The signal transmitting and receiving method based on time division duplexing according to claim 1, characterized in that: the antenna setting method in step 1 further comprises: the multiple antennas reach different receiving antennas according to the signals of different transmitting antennas Channels are set independently of each other.