CN1964217B - Multi-carrier MIMO system and its communication method - Google Patents

Abstract

The provided multi-carrier MIMO communication system comprises: a sending end to send data frame included at least channel estimation signal and user data; and at least one receiving end to receive data frame and generate relative feedback signal and analyze data user. Wherein, the sending end generates scheduling information contained target user and code flow and appointed emission beam according to said feedback signal for adaptive user scheduling. This invention can provide maximal channel capacity, and reduces cost and algorithm complexity.

Description

Multi-carrier MIMO system and its communication method

technical field

The present invention relates to a wireless communication technology using a multiple-input multiple-output antenna system, in particular to a multi-carrier MIMO communication system and a communication method thereof.

Background technique

Future wireless communication systems need to support very high-speed data services, such as video conferencing, video on demand, interactive video games, and so on. According to the requirements mentioned in the ITU-R M1645 document: high-speed wireless services (High Mobility) need to support a rate of up to 100Mbps, and for low-speed (Low Mobility) or fixed wireless (Fixed Wireless) services, it is necessary to reach a rate of 1Gbps.

The rate of a channel in wireless communication is equal to the product of the spectral bandwidth of the channel and the spectral efficiency of the applied technology. In order to increase the rate, it needs to increase its spectral bandwidth or the spectral efficiency of the applied technology. However, frequency resources are limited, so it is impossible to increase the communication rate by increasing the spectrum bandwidth without limit. The best way is to increase the spectrum efficiency of the applied technology.

Generally, spectral efficiency can be improved in two ways. One approach is to improve the spectral efficiency of the link level through physical layer technologies such as advanced coding technology and signal processing technology. Another approach is to achieve system-level spectral efficiency through more flexible resource allocation through high-level control. Multiple Input Multiple Output (MIMO) and Channel-Aware User Scheduling (Channel-Aware User Scheduling) are two corresponding methods to achieve this goal. Random beamforming is a method used to improve the performance of the user scheduling system, which can effectively combine the methods of these two different protocol layers, so as to realize the optimization of system performance. However, modern communication systems are all based on the cellular structure, and the basic communication mode is that a base station in the cellular provides services for many users (Mobile Station, MS) at the same time, which involves the access problem of multiple users-multiple access mode ( Multiple Access). Traditional access methods include FDMA, TDMA and CDMA, all of which are based on the principle of circuit switching (Circuit Switch), that is, each user is assigned a fixed frequency band (FDMA), time slot (TDMA) or spreading code (CDMA).

Taking GSM as an example, the base station allocates 8 time slots in a frame to 8 users for communication in a 200K channel by means of fixed time slot allocation. The advantage of this method is that it can guarantee the delay characteristics of communication services, and is more suitable for services that are sensitive to delay such as voice communication. Its disadvantage is that the fixed resource allocation does not take into account the wireless channel conditions when users communicate. Since the wireless channel varies greatly, if the user is assigned to a channel when its channel is in deep fading, it will lead to loss of system performance.

Future communication systems will be dominated by data services, and the requirements for delay are not too strict. In this case, the multi-access mode of packet switching (Packet Switch) can be adopted. When packet switching is used, the base station needs to allocate channels to different users in real time, which is called user scheduling (User Scheduling) here. Currently, there are two basic user scheduling methods that are applied to wireless communication systems. One is round robin scheduling, that is, channels are allocated to all users in a round robin manner. The effect of this method is the same as that of circuit switching, which ensures the delay characteristics and fairness among users, but does not improve performance. Another _user scheduling technique is Channel-aware Scheduling, which can dynamically assign the current channel usage right to The user with the largest carrier-to-interference ratio (which can be simply considered as max|h _k |). In this case, the performance of the system can be greatly improved. The performance gain obtained by scheduling with the maximum carrier-to-interference ratio is called multiuser diversity (Multiuser Diversity).

However, since channel-aware scheduling determines the allocation of common channels according to channel conditions, its dependence on channel conditions is relatively large. In this way, under some special channel conditions, the performance of the system will drop significantly.

Figures 1(a) and 1(b) show the system structure when the base station (transmitter) has one transmit antenna and has two users (receiver). In this system, channel-aware scheduling determines the allocation of common channels according to channel conditions.

In Figure 2, (a) shows the channel gain when the channel is in good condition; (b) shows the channel gain when there is a Line of Sight (LoS) in the channel; (c) shows the system is in slow fading The condition of the channel gain.

In FIG. 2 , curve 1 represents the time-varying channel gain curve of user 1, curve 2 represents the time-varying channel gain curve of user 2, and the dashed line represents the time-varying average channel gain curve of the current system. It can be seen from (a) that at different times, the system determines the allocation of common channels according to the channel gains of user 1 and user 2, that is, it is allocated to user 1 during the 0-t ₁ period, and allocated to the user 1 during the t ₁ -t ₂ period. Give user 2 and so on, represented by "1" and "2" on the time axis respectively. Finally, the channel gain of the system is the upper envelope of curve 1 and curve 2, and the average of them is calculated to obtain the system average channel gain curve shown by the dotted line.

Comparing (a) and (b), it can be seen that when there is a line-of-sight path in the channel, since the line-of-sight path will reduce the fluctuation of the channel coefficient, it will lead to a decrease in the achievable average channel gain of the system. And, it can be seen from (b) and (c) (period indicated by brackets), when the system fading is relatively slow, the transmission delay will be relatively large.

To solve this problem, P.Viswanath, D.N.C.Tse and R.Laroia et al. proposed a solution (see "Opportunistic beamforming using dumb Anntennas", IEEETrans.Infor.Theory, Vol.48, No.6, pp.1277 -1294.June.2002, hereinafter "Reference 1").

每个用户把其检测到的等效信道增益反馈给基站，进而，基站将信道分配给具有最大等效信道增益的用户。In this method, assuming that the base station is equipped with n _T antennas, and each user is a receiving antenna, the user's channel is a vector Before transmission, the data signal is multiplied by a vector of n _T- dimensional random complex numbers Then, the data signal is transmitted from all n _T antennas. At this time, the channel gain detected by each user is actually an equivalent channel gain that combines the real channel and the transmit vector

Each user feeds back the detected equivalent channel gain to the base station, and then the base station allocates the channel to the user with the largest equivalent channel gain.

For example, in Figures 1a and 1b, the user with the largest equivalent gain is located exactly within the main lobe of the transmit beam formed by the transmit vector _hk . In this way, by changing the random complex vector W, the statistical characteristics of the equivalent channel gain (such as correlation characteristics, time-varying characteristics, etc.) can be changed to meet the requirements of user scheduling.

The performance of the system also largely depends on the probability distribution density function f _pdf (w) of the random vector. The above method is given in the case of a flat fading channel in a narrowband system. However, the current system is usually a broadband system with strong frequency selective fading, so it is impossible to form a beam in a certain direction by directly using the above method. Meanwhile, according to the multi-carrier modulation technique, the signal bandwidth can be divided into many sub-carriers, and each sub-carrier will experience a flat fading channel. In this way, random beamforming can be achieved for each subcarrier. Users can compete for each subcarrier by measuring the equivalent channel gain on each subcarrier.

FIG. 3 shows a schematic diagram of signal processing at the sending end in this case. It can be seen that the data d _i on each subcarrier must be multiplied by a randomly generated vector w ⁿ , n=1, . . . , Nc to form frequency domain signals input to different antennas. Frequency domain signals on different antennas are then processed by IFFT to form time domain signals. The time-domain signal is transmitted through a corresponding antenna after being added with a cyclic prefix. From Figure 3, we can see that for this system, a total of Nc _nT -dimensional random vectors need to be generated, and _nT IFFTs need to be performed. This creates several problems:

1. Random numbers are generally generated through some pseudo-random methods. And what is needed here are some random sequences with time-correlated properties. Generating so many random numbers requires many corresponding pseudo-random generators, resulting in an increase in hardware resources or an increase in algorithm complexity;

2. The performance of this system should depend on the joint probability density function f _pdf (w ₁ , . . . , w _Nc ) of all random vectors. In principle, this function has a certain room for optimization, but it is very difficult in mathematics to optimize a function with many variables purposefully;

3. This solution requires as many IFFT times as the number of transmitting antennas, and the complexity of the algorithm is o(n _T · Nc · LogNc), which is relatively high.

Therefore, it is necessary to provide a communication system and a communication method that can overcome the above disadvantages.

Contents of the invention

The purpose of the present invention is to provide a multi-carrier MIMO communication system.

Another object of the present invention is to provide a communication method for the above multi-carrier MIMO communication system.

According to the first aspect of the present invention, the multi-carrier MIMO communication system of the present invention includes a sending end for sending data frames having at least channel estimation signals and user data, and for receiving data frames sent by the sending end and generating corresponding Feedback signal and restore at least one receiver of user data. Wherein, the sending end includes: a duplexer group and a sending antenna located thereon, for sending data frames and receiving feedback signals from the receiving end; a multi-carrier MIMO scheduler, for generating scheduling information according to the feedback signals; The carrier MIMO data processor is configured to select users to be scheduled according to the scheduling information, and form the data of the selected users into corresponding multi-carrier transmission signals. The receiving end includes: a duplexer group and a receiving antenna on it, which are used to receive data frames from the sending end and send user feedback information; a multi-carrier receiving signal processor is used to generate user feedback data and restore data according to the data frame User data; a feedback information processor, configured to convert user feedback information into feedback signals.

According to the second aspect of the present invention, the communication method of the multi-carrier MIMO communication system of the present invention includes the following steps:

(a) at the receiving end, generate a feedback signal according to the channel fading condition between the transmitting antenna of the transmitting end and the receiving antenna of the receiving end, and feed back the feedback signal to the transmitting end;

(b) at the sending end, receiving the feedback signal, and generating scheduling information according to the feedback signal;

(c) At the sending end, according to the scheduling information, the data of the scheduled user is formed into a corresponding multi-carrier transmission signal, and the multi-carrier transmission signal is sent through the corresponding transmission antenna; and

(d) At the receiving end, restore the user data according to the received transmit beam.

Compared with the prior art, the channel capacity provided by the multi-carrier MIMO communication system and the communication method thereof of the present invention is higher than that provided by the existing multi-carrier MIMO communication method. In addition, since the multi-carrier MIMO communication system of the present invention adopts a new multi-carrier beamformer and a random vector generator, it can overcome that the existing multi-carrier MIMO communication system requires a lot of pseudo-random generators The disadvantage of generating a large number of random numbers, at the same time, the joint probability density function of the random vector can be optimized, and the complexity of the algorithm is also low.

Description of drawings

For further explanation of the present invention, please refer to the accompanying drawings described below:

Fig. 1 (a) and (b) are system structure diagrams when the base station has one transmitting antenna and two users.

Fig. 2 (a) shows the situation of channel gain when the channel condition is good; (b) shows the situation of channel gain when there is line-of-sight path in the channel; (c) shows the situation of channel gain when the system is in slow fading.

FIG. 3 is a schematic diagram of an apparatus for implementing multi-carrier random beamforming in a traditional MIMO system.

FIG. 4 is a frame diagram of a multi-carrier MIMO communication system based on random transmit beamforming according to the present invention.

FIG. 5 is a flowchart of user scheduling in the multi-carrier MIMO communication system shown in FIG. 4 .

FIG. 6 is a schematic diagram of a frame structure adopted by the multi-carrier MIMO communication system of the present invention.

FIG. 7 further illustrates a schematic structural diagram of the transmitting end 10 of the MIMO communication system of the present invention.

FIG. 8 is a specific structural diagram of the multi-carrier beamformer 114 shown in FIG. 7 .

FIG. 9 is a schematic structural diagram of a transmitting radio frequency link group of the transmitting end 10 .

FIG. 10 is a schematic diagram of the duplexer group 130 of the transmitting end 10 of the present invention.

FIG. 11 further illustrates a schematic structural diagram of the receiving end 20 of the MIMO communication system of the present invention.

12 to 14 are performance comparison diagrams of different scheduling methods under actual channel conditions.

Detailed ways

The present invention will be described below in conjunction with the accompanying drawings.

FIG. 4 is a frame diagram of a multi-carrier MIMO communication system according to the present invention, wherein the MIMO communication system includes a transmitting end 10 (base station) and multiple receiving ends 20 (users). FIG. 5 is a flowchart of user scheduling in the MIMO communication system shown in FIG. 4 . FIG. 6 is a schematic diagram of a frame structure adopted by the multi-carrier MIMO communication system of the present invention.

As shown in FIGS. 4-6 , the transmitting end 10 has a multi-carrier MIMO data processor 110 , a multi-carrier MIMO scheduler 120 , a duplexer group 130 and n _T transmitting antennas. Each receiving end 20 has a multi-carrier receiving signal processor 210, a feedback information processor 220, a duplexer group 230 and n _R receiving antennas. Wherein, the number of receiving antennas of each receiving end 20 may be different. The frame structure includes: channel estimation time slots, channel feedback time slots and data transmission time slots, and other time slots can be set according to system requirements, which are simplified here for the convenience of description.

Scheduling Information Acquisition Process

It can be seen from FIG. 6 that before transmitting user data signals, the transmitting end 10 first sends channel estimation signals to the receiving end 20 in the form of transmitting beams from n _T transmitting antennas through the duplexer group 130 .

Assume that the signal sent by the sender 10 is an _nT- dimensional complex vector What each receiver 20 receives is an n _R -dimensional complex vector There is an n _R × n _T dimensional channel fading matrix between the sending end 10 and the receiving end 20:

表示发送端10第i根发送天线和接收端20第j根天线之间的信道传输特性(其中k表示第k个用户)。in,

Indicates the channel transmission characteristics between the i-th transmitting antenna at the transmitting end 10 and the j-th antenna at the receiving end 20 (where k represents the k-th user).

Then, the transfer function of the system can be expressed as:

y _k ＝H _k x _k +μ _k

(2)

k=1,...,K

in is an n _R -dimensional complex vector, representing the white noise at the receiving end 20 .

In this way, for each receiving end 20, it knows the exact channel fading condition, which actually combines the real channel fading condition and the random complex number vector of the transmitting end. According to the channel fading condition, each receiving end 20 can process it through the multi-carrier receiving signal processor 210 to obtain user feedback information and send it to the feedback information processor 220 .

The feedback information processor 220 processes the received user information and converts it into a feedback signal (radio frequency signal) suitable for the MIMO communication system. The feedback signal is fed back to the transmitting end 10 through the antenna of the receiving end 20 through the feedback channel.

After receiving the feedback signal, the antenna of the transmitting end 10 transmits it to the multi-carrier MIMO scheduler 120 . The multi-carrier MIMO scheduler 120 generates scheduling information according to the signal, and uses the generated scheduling information to control the operation of the multi-carrier MIMO data processor 110, so as to make the MIMO communication system reach the scheduling state when the maximum system capacity is reached. That is, optimal user scheduling is performed according to the scheduling information.

The above-mentioned method for obtaining channel fading conditions is performed by using a channel estimation signal (ie, a pilot signal), which inserts a channel estimation signal into a data frame, and the receiving end 20 obtains the channel estimation signal between the transmitting end 10 and the receiving end 20 according to the channel estimation signal. The channel fading condition of the channel is further processed by the multi-carrier receiving signal processor 210 to obtain the user feedback information after processing the channel fading condition.

However, in the present invention, channel fading conditions can also be obtained by using channel blind estimation. That is, there is no need to set a channel estimation time slot in the data frame, and the receiving end 20 obtains the channel fading condition through channel blind estimation while receiving the data sent by the transmitting end 10, and then processes the channel fading condition by the multi-carrier receiving signal processor 210 Feedback information obtained from users. In this case, the waste of frequency spectrum resources caused by the insertion of the channel estimation signal can be avoided.

FIG. 7 further illustrates a schematic structural diagram of the transmitting end 10 of the MIMO communication system of the present invention. FIG. 8 is a specific structural diagram of the multi-carrier beamformer 114 shown in FIG. 7 . FIG. 9 is a schematic structural diagram of a transmitting radio frequency link group of the transmitting end 10, and FIG. 10 is a schematic diagram of a duplexer group 130 of the transmitting end 10 according to the present invention. FIG. 11 further illustrates a schematic structural diagram of the receiving end 20 of the MIMO communication system of the present invention. In FIG. 7 and FIG. 11 , MIMO communication is described using hierarchical spatio-temporal signal processing. For signal processing, other signal processing methods and devices disclosed in the prior art can also be used for execution, such as space-time coding.

User data transmission/reception and scheduling process

sender 10

In FIG. 7 , the transmitting end 10 includes a multi-carrier MIMO data processor 110 , a multi-carrier MIMO scheduler 120 , a duplexer group 130 and n _T transmitting antennas.

The multi-carrier MIMO scheduler 120 includes a receiving radio frequency link group 123 , a MIMO receiving signal processor 122 and a scheduler 121 . Wherein, the receiving radio frequency link group 123 has a number of receiving radio frequency links corresponding to the number of transmitting antennas, and is used to convert the received feedback signal into a corresponding code stream. The MIMO receiving signal processor 122 performs space-time signal processing on the converted code streams to obtain corresponding scheduling information, which includes: the users to be scheduled, the code streams supported by each user, and the specification for sending each code stream A designated transmit beam on a subcarrier. The scheduler 121 controls signal processing of the multi-carrier MIMO data processor 110 using the scheduling information.

The multi-carrier MIMO data processor 110 includes a user selector 111, a plurality of splitters 112 arranged in parallel, a carrier beam splitter 113, a plurality of multi-carrier beamformers 114 arranged in parallel, an adder group 118, and a cyclic prefix group 115. Send the radio frequency link group 116 and the random vector generator 117.

Wherein, under the control of the scheduling information (according to "users to be scheduled" in the scheduling information), the user selector 111 is used to select the users to be scheduled, here the number is expressed as nS, and output corresponding user data.

Under the control of the scheduling information, nS splitters 112 are selected to split the user data of the scheduled nS users, that is, according to the "code stream supported by each user" in the scheduling information, the scheduled The user data of the nS users are divided into L streams for output. L is the sum of the number of streams assigned to the data of all scheduled users.

Then, the L streams output by the demultiplexer 112 are treated as L different layers by the carrier beam allocator 113, and according to the scheduling information "send the designated transmission beam on the designated subcarrier of each code stream", the The transmitted L code streams are allocated to designated transmit beams of designated subcarriers respectively, that is, the L code streams are allocated to frequency domain and air domain channels to form multiple frequency domain signals. Here, assuming that the number of subcarriers in the multi-carrier MIMO communication system is N _c and the number of transmitting antennas is n _T , then the output at this time is N _c ×n _T frequency domain signals, that is, each subcarrier supports n _T transmit beams. Among the N _c ×n _T frequency domain signals, only L frequency domain signals have user data.

Next, the N _c ×n _T frequency-domain signals are respectively input into n _T multi-carrier beamformers 114. The principle is that, for n _T frequency-domain signals on the same subcarrier, they are respectively input into n _T multi-carrier beamformers 114. In one corresponding multicarrier beamformer 114 in the multicarrier beamformer 114, that is, N _c frequency domain signals belonging to the same spatial domain channel among N _c ×n _T frequency domain signals are input to a corresponding multicarrier beamformer 114. Therefore, each multi-carrier beamformer 114 respectively receives N _c frequency domain signals corresponding to the subcarrier beamformer, and each frequency domain signal corresponds to a subcarrier.

The random vector generator 117 generates random vectors, and inputs the generated random vectors into the corresponding multi-carrier beamformers 114 respectively.

Each multi-carrier beamformer 114 performs beamforming processing on the N _c frequency domain signals input therein according to the random vector generated by the random vector generator 117 to form n _{T time domain transmission signals for n T antennas} respectively , that is, each time-domain transmit signal corresponds to one transmit antenna among the n _T transmit antennas. The essence is that each transmitted signal in the time domain corresponds to an independent spatial domain channel of all N _c subcarriers. All n _T multicarrier beamformers 114 will form n _T x n _T transmit signals.

A corresponding adder in the adder group 118 having n _T adders superimposes n _T time-domain transmit signals corresponding to the same transmit antenna to form a total transmit signal. In this way, signals from different multi-carriers The time-domain transmission signals of the beamformer corresponding to the same transmission antenna correspond to an independent space-frequency domain channel. Each adder then outputs the transmit signal it forms into bank 115 of cyclic prefixers. The n _T adders output a total of n _T transmit signals respectively corresponding to one transmit antenna.

The cyclic prefix set 115 includes n _T cyclic prefixes, and each cyclic prefix corresponds to a transmitting antenna. Each cyclic prefixer inserts a cyclic prefix into the transmit signal from the multi-carrier beamformer 114 and corresponds to the same transmit antenna, and generates a corresponding transmit signal with the cyclic prefix inserted. The n _T cyclic prefixers output a total of n _T transmit signals respectively corresponding to the n _T transmit antennas.

The sending radio frequency link group 116 is used to receive n _T transmission signals output from the cyclic prefixer group 115, convert the n _T transmission signals into corresponding radio frequency signals, and combine the radio frequency signals corresponding to each transmission signal It is sent out through the n _T sending antennas on the duplexer group 130 .

Specifically, the multi-carrier beamforming process in the multi-carrier MIMO communication system will be specifically described below with reference to FIG. 8 .

As shown in FIG. 8 , each multi-carrier beamformer 114 includes a serial combination composed of an IFFT transformer 1141 , n _T routing multiplier 1142 and delayer 1143 .

The IFFT converter 1141 receives the corresponding N _c frequency domain signals output by the carrier beam allocator 113, forms serial time domain signals through IFFT transformation, and outputs the serial time domain signals in parallel to the multiplier 1142 and 1143 composed of n _T road serial combination. Wherein, the subcarriers corresponding to the N _c frequency domain signals are different from each other.

其中，

和分别表示第i个多载波波束成形器114中的IFFT变换器1141所输出的第j路串行时域信号的权重和延时，0≤i≤n_T，0≤j≤n_T。At the same time, the random vector generator 117 inputs the generated random vector into the corresponding multi-carrier beamformer 114 among the n _T multi-carrier beamformers 114 . This random vector includes the vector and vector

in,

and respectively represent the weight and delay of the j-th serial time-domain signal output by the IFFT converter 1141 in the i-th multi-carrier beamformer 114, 0≤i≤n _T , 0≤j≤n _T .

对输入其中的串行时域信号进行加权处理，并根据对该串行时域信号进行延时处理，形成一个发送信号。该加权处理和延时处理等效于：The serial combination that each routing multiplier 1142 and delayer 1143 forms is according to the vector that random vector generator 117 inputs

The serial time-domain signal input to it is weighted, and according to Delay processing is performed on the serial time-domain signal to form a transmission signal. This weighting and delaying process is equivalent to:

${\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>\sqrt{{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}}\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="H051B5624920051115E000111.png,H051B5624920051115E000112.png"\; state="\{\{state\}\}">j</figure-callout></span>}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;n</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; CD</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

In this way, each multi-carrier beamformer 114 will form n _T transmission signals, and n _T multi-carrier beamformers 114 will form n _T ×n _T transmission signals. Wherein, the n _T transmit signals formed by each multi-carrier beamformer 114 respectively correspond to one transmit antenna in the n _T transmit antennas.

For the n _T × n _T transmission signals output by n _T multi-carrier beamformers 114, the transmission signals corresponding to the same transmission antenna are superimposed by the corresponding adders in the adder group 118 to form corresponding transmission signals and then input to the loop The corresponding cyclic prefix unit in the prefix unit group 115 inserts a cyclic prefix into the transmit signal input thereto, and sends the signal with the cyclic prefix inserted to the sending radio frequency link group 116 . The n _T cyclic prefixers in the cyclic prefixer group 115 output a total of n _T transmitted signals inserted with cyclic prefixes.

The specific structure of the transmit radio frequency chain group 116 is further described in FIG. 9, which includes n _T parallel transmit radio frequency chains, each transmit radio frequency chain has a modulator 1161, an upconverter 1162 and a power amplifier 1163 connected in series , the power amplifier can be a high-power linear amplifier. Wherein, the n _T transmitting radio frequency links are respectively used to convert the n _T transmitting signals output by the cyclic prefixer group 115 into corresponding radio frequency signals.

FIG. 10 is a schematic diagram of the duplexer group 130 of the transmitting end 10 of the present invention. Wherein, the duplexer group 130 includes n _T parallel duplexers. Each duplexer is connected to a corresponding transmit antenna and is connected to the set of transmit radio frequency links 116 and the set of receive radio frequency links 123 .

Receiver 20

To simplify the description, only one of the receiving terminals 20 is shown here.

In FIG. 11 , the receiving end 20 has a multi-carrier receiving signal processor 210 , a feedback information processor 220 , a duplexer group 230 and n _R antennas.

Wherein, the multi-carrier receiving signal processor 210 includes a receiving radio frequency link group 211 and a MIMO receiving signal processor 212 . The feedback information processor 220 includes a MIMO transmit signal processor 221 and a transmit radio frequency link group 222 .

The receiving radio frequency chain group 211 has parallel receiving radio frequency chains (not shown) that are the same as the number n _R of receiving antennas, and is used to recover the received radio frequency signal into a corresponding code stream, and send it to the MIMO receiving signal for processing device 212.

The MIMO receiving signal processor 212 restores the code stream to original user data and outputs it.

The scheduling process of the present invention will be described below according to different user scheduling methods. For the receiving end 20, in the scheduling of the present invention, for each receiving end 20 with multiple antennas, it can be considered as the same number of receiving ends 20 with one antenna. Therefore, here we only describe the case where each receiving end 20 has one antenna, and this description can be extended to the case where each receiving end 20 has multiple antennas.

first scheduling method

For each receiving end 20 , according to the channel fading condition, the multi-carrier receiving signal processor 210 can process the received signal, obtain user feedback information, and send it to the feedback information processor 220 . Wherein, the user feedback information includes: on each subcarrier, the combination _nk of the best transmission beams for the receiving end, and the signal-to-interference ratio GNI _k corresponding to each transmission beam in the best combination of transmission beams .

${\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}}{\mathrm{<span\; class="notranslate">\; arg</span>}\mathrm{<span\; class="notranslate">\; max</span>}<span\; class="notranslate">\; |</span>{{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}^{<span\; class="notranslate">\; *</span>}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; |</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; GNI</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; |</span>{{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}^{<span\; class="notranslate">\; *</span>}{\mathrm{<span\; class="notranslate">\; w</span>}}_{{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; |</span>{{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}^{<span\; class="notranslate">\; *</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;w</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

Among them, w _n represents the random complex number vector of the sender (equivalent to the ), H _k represents the channel fading matrix between the sending end 10 and the receiving end 20.

The feedback information processor 220 processes the received user feedback information and converts it into a feedback signal suitable for the MIMO communication system. The feedback signal is fed back to the transmitting end 10 through the antenna of the receiving end 20 through the feedback channel.

When the scheduler 121 of the sending end 10 receives the feedback signal, system scheduling is performed. Since each receiving end 20 feeds back its best transmit beam combination _nk on each subcarrier and the signal-to-interference ratio GNI _k corresponding to each transmit beam in the best transmit beam combination, the scheduling process mainly include:

1) Set the user scheduling list SU and the allocated transmit beam list SB to be empty;

2) For each subcarrier, the following steps i) to iii) will be repeated:

i) Compare all the feedback signal-to-interference ratios GNI _k , select a user with the largest signal-to-interference ratio GNI _k to add to the user scheduling list SU, and add the corresponding transmit beam to the allocated transmit beam list SB;

ii) Then, compare all the feedback signal-to-interference ratios GNI _k , select the user with the largest signal-to-interference ratio GNI _k from the unscheduled users, add it to the user scheduling list SU, and put the corresponding transmit beam Added to the allocated transmission beam list SB;

iii) repeat steps i) and ii), until the user scheduling on the carrier is completed;

3) Finally, according to the user scheduling list SU and the allocated transmit beam list SB generated for all subcarriers, the multi-carrier MIMO data processor 110 is controlled to divide the data streams of the scheduled users into independent code streams and allocate them to the designated The designated transmit beam of the subcarrier is transmitted from the transmit antenna.

In the above scheduling step 2), for each subcarrier, if a receiving terminal 20 (user) has been added to the user scheduling list SU, and when another transmission beam in its best transmission beam group is selected, due to The receiver 20 has only one antenna, so it cannot be rescheduled. At this point, the user scheduling for the subcarrier ends.

Meanwhile, in the above scheduling step 2), for each subcarrier, if the transmit beam corresponding to the user has been added to the list of allocated transmit beams, the user cannot be scheduled. At this point, the user scheduling for the subcarrier ends.

For the situation that each receiving end 20 has multiple antennas, if each antenna is assumed as a receiving end (user), then the scheduling situation of multiple antennas at each receiving end and the scheduling situation of only one antenna at each receiving end resemblance.

Second scheduling method

When the multi-carrier MIMO communication system of the present invention considers the interference between transmit beams on each subcarrier and the number of users to be scheduled is fixed M (1<M×N _c <n _T ), for each receiving end 20 , according to channel fading conditions, the multi-carrier received signal processor 210 can process the received signal, obtain user feedback information, and send it to the feedback information processor 220 . Wherein, the user feedback information includes: on each subcarrier, the combination _nk of the best transmission beams for the receiving end 20, the signal-to-interference ratio corresponding to each transmission beam in the best combination _nk of transmission beams GNI _k , and the combination Q _k of the transmitting beam with the least interference at the receiving end. Among them, on each subcarrier, for the number of the best transmit beams in the best transmit beam combination _nk and the number of transmit beams in the (M-1) transmit beam combinations Q _k with the least interference to the receiving end, it can be The selection is made according to the actual channel conditions, and the principle is that the same transmit beam cannot be included in these two combinations at the same time.

${\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</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">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; \}</span>}{\mathrm{<span\; class="notranslate">\; arg</span>}\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; |</span>{{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}^{<span\; class="notranslate">\; *</span>}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; S</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; no</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">\; 6</span>}<span\; class="notranslate">\; )</span>$

Among them, S represents all possible sets of selecting (M-1) different beams with the least interference from n _T beams on each subcarrier.

The feedback information processor 220 processes the received user feedback information and converts it into a feedback signal suitable for the MIMO communication system. The feedback signal is fed back to the transmitting end 10 through the antenna of the receiving end 20 through the feedback channel.

When the scheduler 121 of the sending end 10 receives the feedback signal, system scheduling is performed. At this time, since each receiving end 20 has fed back its best combination of transmit beams _nk on each subcarrier, the signal-to-interference ratio GNI _k corresponding to each transmit beam in the best combination of transmit beams _nk , And the combination Q _k of the (M-1) transmit beams with the least interference to the receiving end, therefore, the scheduling process mainly includes:

1) Set the user scheduling list SU and the allocated transmit beam list SB to be empty;

2) For each subcarrier, the following steps i) to iii) will be repeated:

i) Compare all the feedback signal-to-interference ratios GNI _k , select a user with the largest signal-to-interference ratio GNI _k to add to the user scheduling list SU, and add the corresponding transmit beam to the allocated transmit beam list SB;

ii) For the users in the user scheduling list, find out the corresponding transmission beam with the least interference from its corresponding combination Q _k , and then find out the corresponding user with the largest signal-to-interference ratio according to the transmission beam with the least interference, and adding the user to the user scheduling list, and at the same time, adding the transmit beam corresponding to the user to the allocated transmit beam list;

iii) repeat steps i) and ii), until the user scheduling on the subcarrier is completed;

3) Finally, according to the user scheduling list SU and the allocated transmit beam list SB generated for all sub-carriers, the multi-carrier MIMO data processor 110 is controlled to divide the data streams of the scheduled users into independent code streams and allocate them to designated sub-carriers. The designated transmit beam of the carrier is transmitted from the transmit antenna.

The third scheduling method

When the multi-carrier MIMO communication system of the present invention considers the interference between the transmit beams on each subcarrier and the impact of the interference on the system capacity, for each receiving end 20, according to the channel fading condition, it receives The signal processor 210 can process the received signal, obtain user feedback information, and send it to the feedback information processor 220 . Wherein, the user feedback information includes: on each subcarrier, for the receiving end 20, the combination n _k of the best transmission beams, the equivalent channel corresponding to each transmission beam in the best combination n _k of transmission beams The gain GN _k , the combination Q _k of the transmission beams that interfere the least to the receiving end, and the performance loss ratio D _k,i of each transmitting beam in the combination Q _k to the best transmitting beam at the receiving end.

{D _{k, i} }={GN _k /|h _k ^* w _i | ² , i∈Q _k } (7)

The feedback information processor 220 processes the received user feedback information and converts it into a feedback signal (radio frequency signal) suitable for the MIMO communication system. The feedback signal is fed back to the transmitting end 10 through the antenna of the receiving end 20 through the feedback channel.

When the scheduler 121 of the sending end 10 receives the feedback signal, system scheduling is performed. At this time, since each receiving end 20 feeds back its combination _nk of the best transmitting beams on each subcarrier, and the equivalent channel gain GN _k of each transmitting beam in the combination _nk , the interference to the receiving end is minimal The combination Q _k of transmitting beams and the performance loss ratio D _k,i of each transmitting beam in the combination Q _k to the best transmitting beam at the receiving end, therefore, the scheduling process mainly includes:

1) Set the user scheduling list SU and the allocated transmit beam list SB to be empty;

2) For each subcarrier, the following steps i) to iv) will be repeated:

i) Compare all the returned equivalent channel gains GN _k , select a user with the largest equivalent channel gain GN _k to add to the user scheduling list SU, and add the corresponding transmit beam to the allocated transmit beam list SB ;

ii) For the users in the user scheduling list, find the corresponding minimum interference transmission beam from its corresponding combination Q _k , and then the user with the maximum signal-to-interference ratio corresponding to the minimum interference transmission beam;

iii) According to the feedback performance loss ratio D _k,i , it is judged whether the addition of the user increases the system capacity. If the addition of the user increases the system capacity, the user is added to the user scheduling list, and at the same time, the user The corresponding transmit beam is added to the list of allocated transmit beams. If the addition of the user reduces the system capacity, the user is not added to the user scheduling list, and the user scheduling on the subcarrier is ended;

iv) After the user joins, repeat steps i) and iii) in turn until the user scheduling on the subcarrier ends;

3) Finally, according to the user scheduling list SU and the allocated transmit beam list SB for all subcarriers, the multi-carrier MIMO data processor 110 is controlled to divide the user's data stream into independent code streams, and the designated subcarrier assigned to on the transmit beam and then sent out from the transmit antenna.

Therefore, the third scheduling method can adaptively schedule users, thereby making full use of channel conditions and providing maximum channel capacity.

In order to more clearly reflect the superiority of the scheduling system and scheduling method of the present invention, please refer to Fig. 12 to Fig. 14 , where the performance comparison of different scheduling methods in actual channels is given, where the number of subcarriers N _c =64, the code The number of streams L=3, and the transmit power P=10.

In FIG. 12, the abscissa represents the Ricean factor k, and the ordinate represents the obtained channel capacity. When the number of antennas at the sending end is 2 and the number of users is 32, as the Ricean factor k increases, the channel capacity gradually decreases. Compared with the method disclosed in Reference 1 and the traditional random Gaussian weighting method, the communication method of the present invention is adopted , the decrease in channel capacity is small and relatively flat.

In FIG. 13, the abscissa represents the number of users, and the ordinate represents the obtained channel capacity. When the Ricean factor k=10 and the number of antennas at the transmitting end is 2, as the number of users increases, compared with the method disclosed in Reference 1 and the traditional random Gaussian weighting method, the communication method of the present invention can obtain a larger channel capacity increment.

In FIG. 14, the abscissa represents the number of transmitting antennas at the sending end, and the ordinate represents the obtained channel capacity. When the number of users is 256, with the increase of the number of transmitting antennas, compared with the method disclosed in Reference 1 and the traditional random Gaussian weighting method, the communication method of the present invention can obtain a larger channel capacity increment.

From the above comparison, it can be seen that the channel capacity provided by the communication system and communication method of the present invention is higher than that provided by the method disclosed in Reference 1 and the traditional random Gaussian weighting method.

In summary, the multi-carrier MIMO communication system and communication method of the present invention can perform user scheduling according to current channel conditions and different feedback information, improve the intelligence of system control and communication stability, and always maintain the maximum system capacity. In addition to obtaining the maximum channel capacity, the multi-carrier MIMO communication system of the present invention uses a new algorithm, which can overcome the need for many pseudo-random generators to generate a large number of random numbers in the existing multi-carrier MIMO communication system. At the same time, the joint probability density function of random vectors can be optimized, and the complexity of the algorithm is also low.

Claims (16)

1. A multi-carrier MIMO communication system, comprising a transmitting end (10) for sending at least a data frame having a channel estimation signal and user data, and for receiving the data frame sent by the transmitting end (10), generating a corresponding Feedback signal and restore at least one receiving end (20) of user data, characterized in that: The sending end (10) includes: The first duplexer group (130) and the transmitting antenna located thereon are used to transmit data frames and receive feedback signals from the receiving end (20); A multi-carrier MIMO scheduler (120), configured to generate scheduling information according to the feedback signal; A multi-carrier MIMO data processor (110), configured to select users to be scheduled according to the scheduling information, and form the data of the selected users into corresponding multi-carrier transmission signals, and The receiving end (20) includes: The second duplexer group (230) and the receiving antenna on it are used to receive the data frame from the sending end (10) and send a feedback signal; A multi-carrier receiving signal processor (210), configured to generate user feedback data and restore user data according to the data frame; A feedback information processor (220), configured to convert user feedback data into a feedback signal; Wherein, the multi-carrier MIMO data processor (110) includes: User selector (111), used for selecting the user to be scheduled according to the scheduling information; A plurality of splitters (112) arranged in parallel are used to split the user data of the scheduled users and output multiple code streams; A carrier beam allocator (113), configured to distribute the code streams output by the splitter to the corresponding beams of the corresponding subcarriers specified by the scheduling information according to the scheduling information, to form multiple frequency domain signals; A random vector generator (117), used to generate and output a random vector, which is a weight vector and a delay vector; A plurality of parallel multi-carrier beamformers (114), each multi-carrier beamformer forms a plurality of Time-domain signals corresponding to one transmitting antenna respectively; The adder group (118) has a plurality of adders, and each adder superimposes the time-domain signals corresponding to the same transmit antenna respectively to form a transmit signal; A cyclic prefix set (115), having a plurality of cyclic prefixes, each of which inserts a cyclic prefix into the transmit signal output by the corresponding adder; and The first sending radio frequency link group (116), is used for receiving a plurality of transmission signals output by the cyclic prefixer group (115), and converting the plurality of transmission signals into corresponding radio frequency signals respectively; Wherein, each multicarrier beamformer (114) includes an IFFT converter (1141), and a serial combination of a multi-routing multiplier (1142) and a delayer (1143), wherein, The IFFT converter (1141) performs IFFT transformation on the frequency domain signal from the carrier beam allocator (113) to form a serial time domain signal, and simultaneously inputs the serial time domain signal into the above-mentioned multi-channel serial combination; In the serial combination of each route multiplier (1142) and delayer (1143), the multiplier (1142) and delayer (1143) are respectively based on the weight vector output by the random vector generator (117) and delay The time vector sequentially performs weighting and delay processing on the serial time-domain signal to generate a time-domain signal corresponding to one transmitting antenna. 2. The multi-carrier MIMO communication system as claimed in claim 1, characterized in that, the feedback signal comprises on each subcarrier, the best transmitting beam group of each receiving terminal (20) and the best transmitting beam group The signal-to-interference ratio corresponding to each transmit beam in . 3. The multi-carrier MIMO communication system according to claim 2, characterized in that the feedback signal further includes a combination of transmit beams on each subcarrier that interferes least with each receiving end (20). 4. The multi-carrier MIMO communication system according to claim 1, wherein the feedback signal includes on each subcarrier, the combination of the best transmit beams at each receiving end, the equivalent of each transmit beam in the combination The channel gain, the combination of transmit beams with the least interference to the receiver, and the performance loss ratio of each transmit beam in the combination to the best transmit beam at the receiver. 5. The multi-carrier MIMO communication system according to any one of claims 1 to 4, wherein the scheduling information includes users to be scheduled, code streams supported by each user, and designated subcarriers for sending each code stream The specified transmit beam on . 6. multi-carrier MIMO communication system as claimed in claim 5, is characterized in that, The multi-carrier MIMO scheduler (120) includes: The first receiving radio frequency link group (123), is used for converting the received feedback signal into a corresponding code stream; A first MIMO receiving signal processor (122), configured to perform space-time signal processing on the converted code stream to obtain corresponding scheduling information; and A scheduler (121), configured to control signal processing of the multi-carrier MIMO data processor (110) according to the scheduling information. 7. The multi-carrier MIMO communication system as claimed in claim 6, characterized in that, the first transmitting radio frequency chain group (116) comprises a plurality of parallel transmitting radio frequency chains, respectively outputting the cyclic prefix device group (115) Multiple transmit signals are converted into corresponding radio frequency signals, and each transmit radio frequency link includes a modulator (1161), an up-converter (1162) and a power amplifier (1163) connected in series. 8. The multi-carrier MIMO communication system as claimed in claim 7, characterized in that, The multi-carrier receive signal processor (210) includes: A second receiving radio frequency link group (211), used to demodulate and convert the received radio frequency signal to obtain a corresponding code stream; A second MIMO receiving signal processor (212), used to generate corresponding user feedback data according to the code stream, and simultaneously restore and output user data; and The feedback information processor (220) includes: A MIMO transmit signal processor (221), used for converting user feedback data into a feedback signal; A second transmitting radio frequency link group (222), used to convert the feedback signal into a corresponding radio frequency signal. 9. A multi-carrier MIMO communication method, comprising the following steps: (a) at the receiving end, generate a feedback signal according to the channel fading condition between the transmitting antenna of the transmitting end and the receiving antenna of the receiving end, and feed back the feedback signal to the transmitting end; (b) at the sending end, receiving the feedback signal, and generating scheduling information according to the feedback signal; (c) At the sending end, according to the scheduling information, the data of the scheduled user is formed into a corresponding multi-carrier transmission signal, and the multi-carrier transmission signal is sent through the corresponding transmission antenna; and (d) At the receiving end, restore user data according to the received transmit beam; Wherein, step (c) comprises the following steps: i) Select the user to be scheduled according to the scheduling information; ii) divide the user data of the scheduled user into corresponding code streams according to the scheduling information; iii) According to the scheduling information, each code stream is assigned to the designated transmit beam of the designated subcarrier, and the code streams assigned to the same airspace channel are respectively subjected to IFFT transformation for all subcarriers, and output and transmit antennas in each airspace channel Corresponding parallel multi-channel serial time-domain signals respectively; iv) performing weighting processing and delay processing on each serial time-domain signal in turn to form a corresponding transmission signal, and superimposing the transmission signals corresponding to the same transmission antenna, and then inserting a cyclic prefix into the multi-carrier transmission signal formed after the superposition, Transmit from the corresponding transmit antenna. 10. The communication method according to claim 9, wherein the scheduling information includes users to be scheduled, code streams supported by each user, and designated transmit beams on designated subcarriers for sending each code stream. 11. The communication method according to claim 10, wherein the feedback signal includes, on each subcarrier, the combination of the best transmission beams for the receiving end, the best combination of transmission beams in the combination of transmission beams The corresponding signal-to-interference ratio. 12. The communication method according to claim 11, wherein the feedback signal further comprises a combination of a plurality of transmit beams on each sub-carrier with the least interference to each receiving end. 13. The communication method according to claim 10, wherein, the feedback signal is included on each subcarrier, the combination of the best transmission beams for the receiving end, the combination of each transmission beam in the combination of the best transmission beams The corresponding equivalent channel gain, the combination of the transmitting beams with the least interference to the receiving end, and the performance loss ratio of each transmitting beam in the combination to the best transmitting beam at the receiving end. 14. The communication method as claimed in claim 11, wherein step (b) comprises the steps of: 1) Set the user scheduling list and the allocated transmit beam list to be empty; 2) For each subcarrier, perform the following steps i) to iii): i) Compare all the SIRs fed back, select a user with the largest SIR to add to the user scheduling list, and add the corresponding transmit beam to the list of allocated transmit beams; ii) Then, compare all the feedback SIRs, select the user with the largest SIR from the unscheduled users, add it to the user scheduling list, and add the corresponding transmit beam to the assigned transmit beam in the beam list; iii) repeat steps i) and ii), until the user scheduling on the carrier is completed; 3) Finally, user scheduling of the system is performed according to the user scheduling list and the list of allocated transmission beams generated for all subcarriers. 15. The communication method as claimed in claim 12, wherein step (b) comprises the steps of: 1) Set the user scheduling list and the allocated transmit beam list to be empty; 2) For each subcarrier, perform the following steps i) to iii): i) Compare all the SIRs fed back, select a user with the largest SIR to add to the user scheduling list, and add the corresponding transmit beam to the list of allocated transmit beams; ii) For the users in the user scheduling list, find out the corresponding transmission beam with the least interference from its corresponding combination, and then find out the corresponding user with the maximum signal-to-interference ratio according to the transmission beam with the least interference, and set The user is added to the user scheduling list, and at the same time, the transmit beam corresponding to the user is added to the allocated transmit beam list; iii) repeat steps i) and ii), until the user scheduling on the subcarrier is completed; 3) Finally, perform system user scheduling according to the user scheduling list generated for all subcarriers and the list of allocated transmit beams. 16. The user scheduling method as claimed in claim 13, wherein step (b) comprises the steps of: 1) Set the user scheduling list and the allocated transmit beam list to be empty; 2) For each subcarrier, the following steps i) to iv) will be repeated: i) Comparing all the fed back equivalent channel gains, selecting a user with the largest equivalent channel gain to add to the user scheduling list, and adding the corresponding transmit beam to the allocated transmit beam list; ii) For the users in the user scheduling list, find the corresponding transmission beam with the least interference from its corresponding combination, and then the user with the largest signal-to-interference ratio corresponding to the transmission beam with the least interference; iii) According to the feedback performance loss ratio, it is judged whether the addition of the user increases the system capacity. If the addition of the user increases the system capacity, the user is added to the user scheduling list, and at the same time, the transmission beam corresponding to the user is Add to the list of allocated transmit beams; if the addition of the user reduces the system capacity, do not add the user to the user scheduling list, and end the user scheduling on the subcarrier; iv) After the user joins, repeat steps i) and iii) in turn until the user scheduling on the subcarrier ends; 3) Perform system user scheduling according to the final user scheduling list for all subcarriers and the list of allocated transmission beams.

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