CN108494458A - Signal transmitting apparatus and method based on sub-wave length analog beam former - Google Patents

Abstract

The invention discloses a kind of signal transmitting apparatus and method based on sub-wave length analog beam former, the method includes：Signal p is obtained into transmitting terminal time domain samples sequence after deserializer, Fourier inversion device plus cyclic prefix device and parallel-to-serial converter successivelyIt willPass through N parallel simultaneously_tA signal transmitting filter realizes the forming of sub-wave length analog beam；By the output of every road signal transmitting filter respectively by N_tA signal transmission antenna is transmitted wirelessly.Symbol level ABF performances caused by the case where sub-wave length ABF may be implemented using the present invention, avoid factor intercarrier correlation weak, differ greatly decline.

Description

Signal transmission device and method based on subcarrier-level analog beamformer

technical field

The present invention relates to the field of wireless carrier technology, in particular to a signal transmission device and method based on a subcarrier-level analog beamformer.

Background technique

In recent years, large-scale antenna arrays have become a research hotspot in order to meet the needs of the fifth-generation mobile communication system for significantly improved capacity and spectral efficiency. A large-scale antenna array can bring greater diversity gain and multiplexing gain, which can greatly improve the system spectral efficiency. Considering factors such as complexity, power consumption, and cost, the realization of a large-scale antenna array usually adopts a hybrid beamformer structure.

The hybrid beamformer consists of a baseband digital beamformer and an analog beamformer at the radio frequency end. A typical hybrid beamformer structure is shown in Figure 1. On the base station side, N _s data streams are input to the digital precoder (DBF: Digital Beamformer), and the output passes through After a radio frequency link, it is connected to N _t antennas through a phase shifter, and the phase shifter network constitutes an analog beamformer; on the user side, N _r antennas are connected to N t antennas through a phase shifter RF links are connected, and then output N _s data streams through a digital combiner.

The following behavior is an example, in order to transmit multiple data streams, Note that s represents the transmitted symbol vector of N _s ×1, and F _BB represents The digital precoder, F _RF represents The analog precoder of , then the sampled transmitted signal can be expressed as x=F _RF F _BB s, where

The traditional hybrid beamformer structure assumes a narrow-band block fading channel model, so the user received signal can be expressed as y=HF _RF F _BB s+n, where y represents the received signal of N _r ×1, and H represents N _r ×N _t channel, and n represents additive white Gaussian noise. The signal received by the user is combined by an analog combiner and a digital combiner where w _RF represents The analog combiner, w _BB means The digital combiner of , r represents the received symbol vector of N _s ×1.

The design of the hybrid beamformer usually adopts the "two-step" idea, that is, first design the transmitter analog beamformer F _RF and the receiver analog combiner w _RF according to the actual channel H, and then design the equivalent channel Design the digital beamformer F _BB at the sending end and the digital combiner w _BB at the receiving end. Among them, the design of the analog beamformer is usually implemented by using a codebook-based beam search method. The simplest method is that the beamformer and the combiner traverse the beamforming codebook respectively, and select the optimal beamforming vector and the optimal combining vector that maximize the spectral efficiency.

It should be noted that the above hybrid beamforming solution is only for narrowband communication systems, that is, single carrier modulation systems. A practical broadband communication system usually adopts multi-carrier modulation, such as OFDM (Orthogonal Frequency Division Multiplexing), which is an orthogonal frequency division multiplexing technology. In fact, OFDM is a type of MCM (Multi Carrier Modulation, multi-carrier modulation). In an OFDM system, baseband processing is mainly done in the frequency domain, while radio frequency processing is performed on the time-domain OFDM symbols after IFFT (Inverse Fourier Transform). Therefore, after the hybrid beamforming technology is introduced into the OFDM system, a hybrid structure of frequency domain DBF and time domain ABF is naturally formed.

Compared with the single carrier of the narrowband communication system, the OFDM system adopts multi-carrier modulation. The specific implementation scheme of hybrid beamforming in OFDM system is to calculate the equivalent channel according to the channels experienced by multiple carriers, design the same symbol-level ABF as the single-carrier system, and then design the sub-carrier level DBF. Figure 2 shows the hybrid beamforming structure of the OFDM system. The N _s streams on each carrier are digitally precoded and then subjected to K-point inverse Fourier transform (IFFT), and then add a cyclic prefix (CP). link, connected to the antenna through a phase-shifting network. Multiple receiving antennas on the user side are connected to the radio frequency link through a phase shifter network, then the CP is removed, K-point FFT is performed, and subsequent baseband processing is performed. Therefore, the baseband signal to be processed on the kth carrier of the user can be expressed as

That is to say, the above-mentioned OFDM symbol-level ABF is equivalent to implementing analog beamforming with the same vector for all subcarriers. If the correlation between different subcarriers is weak, the symbol-level ABF processing will produce obvious capacity loss. Especially for OFDMA systems, multiple concurrently scheduled users occupy different subcarriers respectively, and the differences between subcarriers are obvious, and the performance degradation of symbol-level ABF will be more significant.

Contents of the invention

In view of this, the object of the present invention is to propose a signal transmission device and method based on a subcarrier-level analog beamformer, to realize subcarrier-level ABF, and to avoid symbols caused by weak correlation between factor carriers and large differences. Level ABF performance declines.

Based on the above purpose, the present invention provides a signal transmission method based on a subcarrier-level analog beamformer, including:

After the signal p passes through the serial-to-parallel converter, the inverse Fourier transformer, the cyclic prefixer and the parallel-to-serial converter in sequence, the time-domain sample point sequence at the sending end is obtained

Will Simultaneously pass through N _t signal transmission filters in parallel to realize subcarrier-level analog beamforming;

The output of each signal sending filter is wirelessly sent by N _t signal sending antennas respectively.

Further, the method also includes:

Signals are received by N _r signal receiving antennas, and the signals received by N _r antennas are respectively passed through N _r signal receiving filters and then superimposed and combined into signal r;

After the signal r passes through the serial-to-parallel converter, the Fourier transformer, the decyclic prefixer and the parallel-to-serial converter in sequence, the frequency-domain sample point sequence p' at the receiving end is obtained.

Wherein, the signal transmission filter is determined according to the beamforming vector selected for each subcarrier according to its respective channel characteristics:

Determining the optimal beamforming vector at the transmitting end for the subcarriers transmitted by the signal transmitting antenna connected to each signal transmitting filter;

A time-domain beamforming filter is determined according to the optimal beamforming vector of the transmitting end as the signal sending filter.

Wherein, the signal receiving filter is determined according to the beam combining vector selected for each subcarrier according to its respective channel characteristics:

For the subcarriers received by the signal receiving antenna connected to each signal receiving filter, determine the optimal beam combining vector at the receiving end;

A time-domain beam combining filter is determined according to the optimal beam combining vector of the receiving end as the signal receiving filter.

The present invention also provides a signal transmission device based on a subcarrier-level analog beamformer, including: a signal transmission device located at the base station side; wherein, the signal transmission device includes:

A series-to-parallel converter, an inverse Fourier transformer, a cyclic prefixer, and a parallel-to-serial converter are connected in series to convert the signal p into a sequence of time-domain samples at the sending end

N _t signal transmission filters are all connected to the output terminals of the parallel-to-serial converter, and are used to At the same time, N _t channels of filtering are performed in parallel to realize analog beamforming;

The N _t signal sending antennas are respectively connected to the N _t signal sending filters, and are used for wirelessly sending the output signals of the signal sending filters of each channel.

The present invention also provides a signal transmission device based on a subcarrier-level analog beamformer, including: a signal receiving device located on the user side; wherein, the signal sending device includes:

N _r signal receiving antennas for receiving wireless signals;

N _r signal receiving filters, the input end of each signal receiving filter is respectively connected to an antenna, and the output ends of each signal receiving filter are connected to each other, and the signals received by the N _r antennas are respectively received by N _r signal receiving The filter is superimposed and combined into a signal r after filtering;

A series-to-parallel converter, a Fourier transformer, a decyclic prefixer and a parallel-to-serial converter connected in series in sequence are used to convert the signal r into a frequency-domain sample point sequence p' at the receiving end.

In the technical solution of the embodiment of the present invention, before the signal is transmitted wirelessly through N _t signal transmitting antennas, the signal first passes through N _t signal transmitting filters in parallel to perform subcarrier-level analog beamforming, so that the subcarrier-level analog beamforming of different channels can be ensured. Symbol-level ABF performance, thereby effectively improving the spectral efficiency of the system.

The signal transmission filter is determined according to the beamforming vector selected for each subcarrier's respective channel characteristics, that is, the signal transmission filter designed after selecting the best ABF vector for each subcarrier's respective channel characteristics The device can guarantee the ABF performance of different sub-carrier channels to the greatest extent.

Description of drawings

FIG. 1 is a structure of a narrowband hybrid beamformer in the prior art;

Fig. 2 is the hybrid beamformer structure of the OFDM system in the prior art;

FIG. 3 is a conceptual diagram of a subcarrier-level ABF provided by an embodiment of the present invention;

FIG. 4 is a structural diagram of a signal transmission device located on the base station side in a signal transmission device based on a subcarrier-level analog beamformer provided by an embodiment of the present invention;

FIG. 5 is a structural diagram of a signal receiving device on the user side in a signal transmission device based on a subcarrier-level analog beamformer provided by an embodiment of the present invention;

FIG. 6 is a flowchart of a signal transmission method based on a subcarrier-level analog beamformer provided by an embodiment of the present invention;

FIG. 7 is a flowchart of a method for determining a signal transmission filter provided by an embodiment of the present invention;

FIG. 8 is a flowchart of a method for determining a signal receiving filter provided by an embodiment of the present invention;

FIG. 9 is a comparison graph of spectral efficiency between subcarrier-level ABF and symbol-level ABF under a Rayleigh fading channel provided by an embodiment of the present invention;

FIG. 10 is a comparison graph of spectral efficiency between subcarrier-level ABF and symbol-level ABF under a millimeter wave channel provided by an embodiment of the present invention;

Fig. 11 is a comparison graph of spectrum efficiency between subcarrier-level ABF and symbol-level ABF under the millimeter wave channel OFDMA system provided by the embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

Those skilled in the art will understand that unless otherwise stated, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Additionally, "connected" or "coupled" as used herein may include wireless connection or wireless coupling. The expression "and/or" used herein includes all or any elements and all combinations of one or more associated listed items.

It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are to distinguish two entities with the same name but different parameters or parameters that are not the same, see "first" and "second" It is only for the convenience of expression, and should not be construed as a limitation on the embodiments of the present invention, which will not be described one by one in the subsequent embodiments.

The inventors of the present invention consider that since signals on different subcarriers experience different channels, the ABF scheme in the prior art is equivalent to using the same vector for all subcarriers to implement analog beamforming, so that some subcarriers are in When implementing analog beamforming with the same vector, the performance of the signal ABF degrades significantly. Therefore, in the technical solution of the present invention, ABF is performed separately for different subcarriers, that is, subcarrier-level ABF, and corresponding DBFs are also designed separately for different carriers. That is to say, the optimal ABF vector is selected for each subcarrier according to its respective channel characteristics; thereby avoiding the degradation of symbol-level ABF performance caused by weak correlation between subcarriers and large differences, and can effectively improve MIMO ( Spectrum Efficiency of Massive Multiple-Antenna, Multiple-Input Multiple-Output)-OFDM System.

The technical solutions of the embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

Figure 3 is a conceptual diagram of ABF at the sub-carrier level, that is, consider implementing ABF on the data symbols on each sub-carrier before IFFT. remember in Β _k is the best codebook on the kth subcarrier, that is, the best beamforming vector.

In codebook-based beam search, given a codebook set C={C ₁ ,C ₂ ,...,C _M }, where M is the codebook dimension, Β _k ∈C, the selection from the codebook set can The codebook that maximizes the channel capacity of the subcarriers is the optimal codebook.

To simplify the description, only the output signal p={p ₁ ,p ₂ ,...,p _K } to one radio frequency link after digital precoding is considered (the processing of each output signal after digital precoding is the same as below). If frequency-domain subcarrier-level ABF is performed on the signal, the following expression 1 is given:

in, It is a set of B ₁ ~B _K , B ⁿ =[B _1n ,B _2n ,...,B _Kn ], n=1,2,...,N _t . After that, IFFT by row has the following expression 2:

in, q=F ^-1 (p), Represents circular convolution, and F ^-1 represents IFFT.

Since the OFDM system needs to add a cyclic prefix after the signal is IFFT, the circular convolution of the signal q ^T and b ^k is equivalent to the signal obtained by adding the cyclic prefix to the signal q ^T Perform linear convolution with b ^k , as shown in Expression 3:

Based on the above analysis, a signal transmission device based on a subcarrier-level analog beamformer provided by an embodiment of the present invention may include a signal sending device on the base station side, and may further include a signal receiving device on the user side.

Wherein, the structure of the signal transmission device is as shown in Figure 4, including: N _t signal transmission filters 405 and N _t signal transmission antennas 406, and serial-to-parallel converters 401 and inverse Fourier transformers 402 connected in series in sequence , adding a cyclic prefixer 403 and a parallel-to-serial converter 404 .

Among them, the series-to-parallel converter 401, the inverse Fourier transformer 402, the cyclic prefixer 403 and the parallel-to-serial converter 404, which are connected in series, are used to convert the signal p into a time-domain sample point sequence at the sending end

The input terminals of the N _t signal transmission filters 405 are all connected to the output terminals of the parallel-to-serial converter 404 for converting At the same time, N _t channels of filtering are performed in parallel to realize analog beamforming of subcarriers; wherein, N _t is a natural number greater than 0.

The N _t signal transmitting antennas 406 are respectively connected to the output ends of the N _t signal transmitting filters 405 , and are used for wirelessly transmitting the output signals of each signal transmitting filter 405 .

The structure of the signal receiving device is shown in Figure 5, including: a serial-to-parallel converter 503, a Fourier transformer 504, a decyclic prefixer 505 and a parallel-to-serial converter 506 connected in series, and N _r signal receiving antennas 501 , N _r signal receiving filters 502; further, a baseband processing unit (not marked in the figure) may also be included.

Wherein, N _r signal receiving antennas 501 are used to receive wireless signals; N _r is a natural number greater than 0.

The input end of each signal receiving filter 502 is connected to a signal receiving antenna 501 respectively, and the output ends of each signal receiving filter 502 are connected to each other, and are used to pass the signals received by N _r signal receiving antennas 501 through N _r signal receiving antennas respectively. The filter is superimposed and combined into a signal r after filtering;

A series-to-parallel converter 502, a Fourier transformer 504, a decyclic prefixer 505, and a parallel-to-serial converter 506, which are connected in series, are used to convert the signal r into a frequency-domain sample point sequence p at the receiving end;

The baseband processing unit is used to perform other baseband processing on p to obtain the desired signal.

Based on the above-mentioned signal transmission device based on a subcarrier-level analog beamformer, an embodiment of the present invention provides a signal transmission method based on a subcarrier-level analog beamformer, the process of which is shown in Figure 6, including the following steps:

S601: After the signal p passes through the serial-to-parallel converter, the inverse Fourier transformer, the cyclic prefixer and the parallel-to-serial converter in sequence, the time-domain sample point sequence at the sending end is obtained

Specifically, the signal p vector corresponds to K data symbols on K subcarriers. In the signal transmitting device at the base station side, the serial-to-parallel converter 401, the inverse Fourier transformer 402, and the cyclic prefix adding device 403 are sequentially connected in series. After completing the K-point IFFT and adding a cyclic prefix (assuming that the number of cyclic prefix points is KP), the form is still (K+KP) symbols in parallel; through the parallel-to-serial converter 404, it becomes serial (K+KP) sequence of dot time domain symbols

S602: will At the same time, through N _t signal transmission filters in parallel, sub-carrier level analog beamforming is realized.

Specifically, the (K+KP) point time-domain symbol sequence output by the parallel-to-serial converter 404 Simultaneously, through N _t signal sending filters 405 in parallel, sub-carrier level analog beamforming is realized.

S603: Wirelessly transmit the outputs of the N _t signal transmitting filters 405 by the N _t signal transmitting antennas 406 respectively.

After the signal sent by the signal sending antenna 406 is transmitted in space, it can be received and processed by the signal receiving device through the following steps:

S604: Receive signals through N _r signal receiving antennas, and superimpose and combine the signals received by N _r antennas through N _r signal receiving filters to form signal r;

Specifically, on the user side, the signal is received by the N _r signal receiving antennas 501 of the signal receiving device, and the signals received by the N _r signal receiving antennas 501 are respectively passed through the N _r signal receiving filters 502 and then superimposed and combined into a signal r .

S605: Pass the signal r through the serial-to-parallel converter, the Fourier transformer, the decyclic prefixer, and the parallel-to-serial converter in sequence to obtain the frequency-domain sample point sequence p' at the receiving end;

Specifically, after the signal r passes through the serial-to-parallel converter 503 , the Fourier transformer 504 , the decyclic prefixer 505 and the parallel-to-serial converter 506 of the signal receiving device in sequence, the frequency-domain sample point sequence p' at the receiving end is obtained.

S606: Perform other baseband processing on p'.

Specifically, the baseband processing unit 507 of the signal receiving device performs other baseband processing on p'.

The above-mentioned N _t signal transmission filters 405 are determined according to the beamforming vector selected for each subcarrier according to its respective channel characteristics. The specific process is shown in FIG. 7 , including the following steps:

S701: Determine an optimal beamforming vector at the transmitting end for the subcarriers transmitted by the signal transmitting antenna 406 connected to each signal transmitting filter 405.

In this step, a beam search is performed on the subcarriers transmitted by the signal transmitting antenna 406 connected to each signal filter, and an optimal beamforming vector at the transmitting end is found for each subcarrier.

Specifically, in codebook-based beam search, a given codebook set C={C ₁ ,C ₂ ,...,C _M }, where M is the codebook dimension; for the kth subcarrier, the codebook In this set, select the codebook that can maximize the channel capacity of the subcarrier as the optimal codebook, that is, the optimal beamforming vector Β _k ∈ C of the kth subcarrier at the sending end, k=1,2,..., K. K is the number of subcarriers.

S702: Determine a time-domain beamforming filter according to the optimal beamforming vector as the signal sending filter.

Specifically, the optimal beamforming vector of each subcarrier is arranged as shown in Expression 4 below:

Furthermore, IFFT is taken by row, as shown in expression five:

Among them, Β _k is the optimal beamforming vector on the kth subcarrier, k=1,2,...,K; K is the number of subcarriers, F ^-1 means IFFT; N _t time domain beamforming is obtained filters, respectively Send filter as the signal.

The above-mentioned N _r signal receiving antennas 501 can be designed according to the following method, and the flow process is shown in Figure 8, including the following steps:

S801: Determine an optimal beam combining vector at the receiving end for the subcarriers received by the signal receiving antenna 501 connected to each signal receiving filter.

Specifically, in codebook-based beam search, a given codebook set E={E ₁ , E ₂ ,...,E _N }, where N is the dimension of the codebook; for the kth subcarrier, the code In this set, select the codebook that can maximize the channel capacity of the subcarrier as the optimal codebook, that is, the optimal beam combining vector D _k ∈ E of the kth subcarrier at the receiving end, k=1,2,..., K. K is the number of subcarriers.

S802: Determine a time-domain beam combining filter according to the optimal beam combining vector as the signal receiving filter.

Specifically, the optimal beam combining vector of each subcarrier is arranged as shown in the following expression six:

Furthermore, IFFT is taken by row, as shown in Expression 7:

In expressions six and seven, is the set of D ₁ ~D _K , D _k is the optimal beam combining vector on the kth subcarrier, k=1,2,...,K; K is the number of subcarriers, F ^-1 means IFFT; get N _r time-domain beamcombining filters, respectively As the signal receiving filter.

The following is a simulation for the technical solution of the embodiment of the present invention, the simulation performance index is spectrum efficiency, and the parameter configuration is shown in the following table:

Table I

The simulation results of the Rayleigh fading channel are shown in Figure 9, and the simulation results of the millimeter wave channel are shown in Figure 10. It can be seen that in the Rayleigh fading channel, when the SNR is 0dB, the spectral efficiency of the subcarrier-level ABF is 2.4 times higher than that of the traditional symbol-level ABF; The spectral efficiency of ABF is 7% higher than that of traditional symbol-level ABF. It can be seen that the spectral efficiency is greatly improved under the Rayleigh channel, but the spectral efficiency is not significantly improved under the millimeter wave channel. This is mainly because the channel correlation on different subcarriers is relatively strong under the millimeter wave channel.

In an OFDMA system, different resource blocks are required to be allocated to different users. At this time, the channels on different resource blocks are independent of each other. The simulated spectrum efficiency curve under the mmWave channel is shown in Figure 11. It can be seen that under the mmWave channel, the OFDMA system distributes 1200 subcarriers to 10 users on average. When the signal-to-noise ratio is 0dB, the spectral efficiency of subcarrier-level ABF is 2.2 times higher than that of traditional symbol-level ABF.

It can be seen that, no matter for the Rayleigh fading channel or the millimeter wave channel, the subcarrier-level ABF structure and scheme proposed by the present invention can greatly improve the spectrum efficiency compared with the traditional symbol-level ABF.

Therefore, in the technical solution of the embodiment of the present invention, before the signal is wirelessly transmitted through N _t signal transmitting antennas, the signal first passes through N _t signal transmitting filters in parallel to perform subcarrier-level analog beamforming, so that different subcarrier channel channels can be guaranteed ABF performance, thereby effectively improving the spectral efficiency of the system.

The signal transmission filter is determined according to the beamforming vector selected for each subcarrier's respective channel characteristics, that is, the signal transmission filter designed after selecting the best ABF vector for each subcarrier's respective channel characteristics The device can guarantee the ABF performance of different sub-carrier channels to the greatest extent.

Those skilled in the art will appreciate that the present invention includes devices related to performing one or more of the operations described in this application. These devices may be specially designed and fabricated for the required purposes, or they may include known devices found in general purpose computers. These devices have computer programs stored therein that are selectively activated or reconfigured. Such a computer program can be stored in a device (e.g., computer) readable medium, including but not limited to any type of medium suitable for storing electronic instructions and respectively coupled to a bus. Types of disks (including floppy disks, hard disks, CDs, CD-ROMs, and magneto-optical disks), ROM (Read-Only Memory, read-only memory), RAM (Random Access Memory, random memory), EPROM (Erasable Programmable Read-Only Memory, Erasable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory, Electrically Erasable Programmable Read-Only Memory), flash memory, magnetic card or optical card. That is, a readable medium includes any medium that stores or transmits information in a form readable by a device (eg, a computer).

Those skilled in the art will understand that computer program instructions can be used to implement each block in these structural diagrams and/or block diagrams and/or flow diagrams and combinations of blocks in these structural diagrams and/or block diagrams and/or flow diagrams . Those skilled in the art can understand that these computer program instructions can be provided to general-purpose computers, professional computers, or processors of other programmable data processing methods for implementation, so that the computer or processors of other programmable data processing methods can execute the present invention. A scheme specified in a block or blocks of a structure diagram and/or a block diagram and/or a flow diagram of the invention disclosure.

Those skilled in the art can understand that the various operations, methods, and steps, measures, and solutions in the processes discussed in the present invention can be replaced, changed, combined, or deleted. Further, other steps, measures, and schemes in the various operations, methods, and processes that have been discussed in the present invention may also be replaced, changed, rearranged, decomposed, combined, or deleted. Further, steps, measures, and schemes in the prior art that have operations, methods, and processes disclosed in the present invention can also be alternated, changed, rearranged, decomposed, combined, or deleted.

Those of ordinary skill in the art should understand that: the discussion of any of the above embodiments is exemplary only, and is not intended to imply that the scope of the present disclosure (including claims) is limited to these examples; under the idea of the present invention, the above embodiments or Combinations between technical features in different embodiments are also possible, steps may be carried out in any order, and there are many other variations of the different aspects of the invention as described above, which are not presented in detail for the sake of brevity. Therefore, any omissions, modifications, equivalent replacements, improvements, etc. within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A signal transmission method based on a subcarrier-level analog beamformer, comprising: After the signal p passes through the serial-to-parallel converter, the inverse Fourier transformer, the cyclic prefixer and the parallel-to-serial converter in sequence, the time-domain sample point sequence at the sending end is obtained Will Simultaneously pass through N _t signal transmission filters in parallel to realize subcarrier-level analog beamforming; The output of each signal sending filter is wirelessly sent by N _t signal sending antennas respectively. 2. The method according to claim 1, further comprising: Signals are received by N _r signal receiving antennas, and the signals received by N _r antennas are respectively passed through N _r signal receiving filters and then superimposed and combined into signal r; After the signal r passes through the serial-to-parallel converter, the Fourier transformer, the decyclic prefixer and the parallel-to-serial converter in sequence, the frequency-domain sample point sequence p' at the receiving end is obtained. 3. The method according to claim 1 or 2, wherein the signal transmission filter is determined according to the beamforming vector selected for each subcarrier according to its respective channel characteristics: Determining the optimal beamforming vector at the transmitting end for the subcarriers transmitted by the signal transmitting antenna connected to each signal transmitting filter; A time-domain beamforming filter is determined according to the optimal beamforming vector of the transmitting end as the signal sending filter. 4. The method according to claim 3, wherein the determining the time-domain beamforming filter according to the optimal beamforming vector of the transmitting end specifically comprises: According to the following expressions 4 and 5, N _t time-domain beamforming filters are obtained, respectively: Wherein, Β _k is the optimal beamforming vector on the kth subcarrier, k=1, 2,..., K; K is the number of subcarriers, and F ^-1 represents IFFT. 5. The method according to claim 1 or 2, wherein the signal reception filter is determined according to the beam combining vector selected for it by the respective channel characteristics of each subcarrier: For the subcarriers received by the signal receiving antenna connected to each signal receiving filter, determine the optimal beam combining vector at the receiving end; A time-domain beam combining filter is determined according to the optimal beam combining vector of the receiving end as the signal receiving filter. 6. The method according to claim 5, wherein the determining the time-domain beam combining filter according to the optimal beam combining vector of the receiving end specifically comprises: According to the following expressions 6 and 7, N _r time-domain beamforming filters are obtained, respectively Wherein, D _k is the optimal beam combining vector on the kth subcarrier, k=1,2,...,K; K is the number of subcarriers, and F ^-1 represents IFFT. 7. A signal transmission device based on a subcarrier-level analog beamformer, comprising: a signal transmission device located at the base station side; wherein, the signal transmission device includes: A series-to-parallel converter, an inverse Fourier transformer, a cyclic prefixer, and a parallel-to-serial converter are connected in series to convert the signal p into a sequence of time-domain samples at the sending end N _t signal transmission filters are all connected to the output terminals of the parallel-to-serial converter, and are used to At the same time, N _t channels of filtering are performed in parallel to realize analog beamforming; The N _t signal sending antennas are respectively connected to the N _t signal sending filters, and are used for wirelessly sending the output signals of the signal sending filters of each channel. 8. The device according to claim 7, wherein the N _t signal receiving filters are respectively It is obtained according to the following expressions 4 and 5: Wherein, Β _k is the optimal beamforming vector on the kth subcarrier, k=1, 2,..., K; K is the number of subcarriers, and F ^-1 represents IFFT. 9. A signal transmission device based on a subcarrier-level analog beamformer, comprising: a signal receiving device located on the user side; wherein, the signal sending device includes: N _r signal receiving antennas for receiving wireless signals; N _r signal receiving filters, the input end of each signal receiving filter is respectively connected to an antenna, and the output ends of each signal receiving filter are connected to each other, and the signals received by the N _r antennas are respectively received by N _r signal receiving The filter is superimposed and combined into a signal r after filtering; A series-to-parallel converter, a Fourier transformer, a decyclic prefixer and a parallel-to-serial converter connected in series in sequence are used to convert the signal r into a frequency-domain sample point sequence p' at the receiving end. 10. The device according to claim 9, characterized in that, the N _r signal receiving filters are respectively It is obtained according to the following expressions 6 and 7: Wherein, D _k is the optimal beam combining vector on the kth subcarrier, k=1,2,...,K; K is the number of subcarriers, and F ^-1 represents IFFT.