CN109818661A - A Communication Method Based on Signal Spatial Alignment - Google Patents

Abstract

The present invention provides a communication method based on signal space alignment. The method includes: each user performs coding processing on information to be sent, generates a sending signal, and sends the sending signal to a relay node; Performing in the middle: receiving the transmitted signal and generating the received signal, and encoding the received signal to obtain a sum signal; the signal receiving end eliminates the received interference message to obtain a valid signal. Applying the embodiment of the present invention, taking the main network as the Y channel and the secondary network as the X-channel coexistence network with a bidirectional single relay node as the system model diagram, according to the physical layer network coding technology under the generalized signal alignment, it can be arbitrary for the primary and secondary networks. The model diagram of the number of users leads to the scheme of improving the network multiplexing gain and improving the system performance.

Description

A Communication Method Based on Signal Spatial Alignment

technical field

The present invention relates to the technical field of wireless communication, in particular to a communication method based on signal space alignment.

Background technique

The purpose of image dehazing is to reduce the interference of fog as much as possible from the image blurred by fog, restore the scene target, enhance the contrast and clarity of the image, restore the details of the image, and improve the visibility of the image. Most of the current dehazing algorithms are used in land scenes, especially in traffic monitoring and other occasions. There are few dehazing algorithms that specialize in special occasions such as sea fog.

Since the development of communication, it has gradually transitioned from wired communication to wireless communication. From the successful demonstration of wireless telegraphy by Marconi in 1897, wireless communication technology has been extensively studied. Wireless communication has developed from pure mobile calls to wireless multimedia application platforms capable of file transfer, audio and video functions, and the wide application of interactive content such as file transfer, audio and video, etc., will place higher requirements on network quality. To meet these demands, future wireless communication systems need to provide better flexibility and scalability to meet diverse demands. At present, the use of relay node technology in a wireless network can improve the system performance of the network, expand the coverage, improve the spectrum utilization rate, and save network resources. The multi-antenna feature of the relay node can make the wireless network form a MIMO system, thereby further improving the system performance. The main focus of current communication is new technologies such as MIMO and network coding.

MIMO technology was proposed by Marconi in Italy in 1908, and is mainly used to solve the fading problem in wireless channels. The relay node and mobile station in the traditional mobile communication system can be equipped with multiple antennas to form a MIMO communication link, so that the system capacity of the link between the relay node and the mobile station can be improved, and the system can be greatly improved. communication efficiency. The combination of MIMO technology and distributed antenna system can not only inherit the advantages of the latter, reduce the path loss in the process of signal transmission, reduce the shadow effect, but also greatly improve the capacity of the system. Compared with the traditional single-antenna system, the MIMO system can greatly improve the channel capacity, making it close to the Shannon channel capacity, which provides a prospect for solving the capacity demand problem of big data services.

The ultra-high-speed information transmission rate of the future wireless communication system poses a great challenge to the existing communication network structure. For the problem that the existing wireless spectrum resources are relatively tight, the future wireless communication network may use the frequency band higher than 3GHz, and the attenuation of the wireless signal will be serious when it propagates in the high-frequency wireless medium, so the coverage of the base station will be greatly reduced. . In order to guarantee the transmission rate, it is necessary to greatly increase the transmit power in the mobile terminal. However, the increase in the transmit power of the mobile terminal will inevitably increase the radiation risk of the mobile terminal user, and it is also necessary to improve the existing battery power storage technology. The relay node transmission technology can solve the above problems very well. The core idea is to arrange low-cost and low-power relay nodes in the cell, which can improve the system throughput, expand the coverage of cell signals, and especially improve the Signal quality of users close to the cell border.

In the two-way wireless relay node channel, the two nodes send their respective data packets through different time slots, and the relay node combines the two data packets into one network packet and sends them to the respective nodes. Physical layer network coding technology requires strict time synchronization, allowing two nodes to send data packets at the same time, thus saving time slots, which will lead to insufficient waste of antenna resources and low utilization of spectrum resources.

SUMMARY OF THE INVENTION

In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a communication method based on signal space alignment, with the main network as the Y channel and the secondary network as the X channel coexisting network with a bidirectional single relay node as a system model diagram , according to the physical layer network coding technology under the generalized signal alignment, the scheme of improving the network multiplexing gain and improving the system performance can be obtained according to the model diagram of the primary and secondary network for any number of users.

In order to achieve the above purpose and other related purposes, the present invention provides a communication method based on signal space alignment. In the network, for any user N, the number of information sent by user N is N/2, where M is greater than or equal to 3, and N is greater than or equal to 4. In the main network, information can be sent and received for any user. In the network, any user in 2N can only perform signal transmission, and any user in 2N-1 can only perform signal reception; the method includes:

Each user encodes the information to be sent, generates a sending signal, and sends the sending signal to the relay node;

Performing in the relay node: receiving the transmitted signal and generating a received signal, and encoding the received signal to obtain a sum signal;

The signal receiving end removes the received interference message to obtain a valid signal.

In a specific implementation of the present invention, the step of receiving the transmitted signal and generating the received signal includes:

receiving the transmitted signal;

Determine the receiving matrix and signal-to-noise ratio;

A received signal is generated based on the transmit-receive matrix and the signal-to-noise ratio.

In the specific implementation of the present invention, the specific expression for generating the received signal is:

where y ^[r] is the received signal, r is the relay node, N is the number of users, H ^[N,r] is the channel matrix from user N to relay node r, V _N is the set of precoding vectors from user i to user j , S _N is the set of signal vectors sent from user i to user j, and n ^[r] is the signal-to-noise ratio of the relay node r.

In the specific implementation mode of the present invention, the specific expression of the sum signal is:

Among them, M is the number of users of the primary network, N is the number of users of the secondary network, and s _{M, M-1} are the signals sent by user M and user M-1.

In the specific implementation of the present invention, the valid message received by user 1 of the main network is:

The valid messages received by user 1 of the secondary network are:

Among them, y ₁₁ is the effective signal of the main network, is the effective signal of the secondary network, u ₁ represents the receiving matrix of the main network user 1, n ₁ represents the signal noise of the main network user 1, U ₁ represents the receiving matrix of the secondary network user 1, represents the noise of user 1 of the secondary network.

As described above, a communication method based on signal space alignment provided by the embodiment of the present invention aims to firstly take the half-duplex relay node as a reference, and the bidirectional transmission process is divided into an uplink phase and a downlink phase. The stage aligns the signals between the communicating users to the same dimension, and the relay node aligns the interacting signals into a transformed subspace and designs the relay node processing matrix to broadcast the message in the BC stage. Therefore, in a multi-user wireless communication network, the data efficiency will drop sharply due to the interference caused by simultaneous transmission of multiple source nodes. Taking the main network as the Y channel and the secondary network as the X channel, the bidirectional single-relay node of the coexisting network is the system model diagram. According to the physical layer network coding technology under the generalized signal alignment, the model diagram of the primary and secondary networks with any number of users can be obtained. A scheme to improve network multiplexing gain and improve system performance is proposed.

Description of drawings

FIG. 1 is a schematic flowchart of a communication method based on signal space alignment according to an embodiment of the present invention.

FIG. 2 is another schematic flowchart of a communication method based on signal space alignment according to an embodiment of the present invention.

Detailed ways

The embodiments of the present invention are described below through specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

See Figure 1-2. It should be noted that the drawings provided in this embodiment are only to illustrate the basic concept of the present invention in a schematic way, so the drawings only show the components related to the present invention rather than the number, shape and the number of components in actual implementation. For dimension drawing, the type, quantity and proportion of each component can be changed at will in actual implementation, and the component layout may also be more complicated.

As shown in FIG. 1 and FIG. 2 , an embodiment of the present invention provides a communication method based on signal space alignment, and the method includes:

S101, each user performs encoding processing on the information to be sent, generates a sending signal, and sends the sending signal to a relay node.

Based on the fact that each node has global channel state information that remains unchanged, and the node operates in half-duplex mode, it is assumed that the relay node has Nr antennas, each user has Nt antennas, and sends M-1 independent messages . The whole process consumes 2 time slots: the uplink (MAC) phase and the downlink (BC) phase. The signal sent by the i-th user on the left to the j-th user on the right is denoted as S ^[i,j] . Then in the MAC stage, all nodes send messages to the relay node, and the relay node will receive a total of M(M-1)+N·N/2 independent signals from the primary and secondary networks. Calculate the expressions of the signals sent by the primary and secondary networks respectively:

The mainnet sends a signal to express:

The secondary network sends a signal to express:

Among them, v ^[j+1,i] represents the precoding vector of the signal from user i to user j+1, s ^[j+1,i] represents the signal from user i to user j+1, M is the user of the main network number, N is the number of users of the secondary network.

S102: Execute in the relay node: receive the transmitted signal and generate a received signal, and obtain a sum signal after encoding the received signal.

In the MAC phase, the transmitted signal of the terminal is precoded and then sent to the relay node, then the received signal of the relay node is:

in, Represents the channel matrix between the ith user and the relay node, and obeys a complex Gaussian random distribution with zero mean and variance σ ² . n ^[r] ∈ C ^Nr×1 , which means that the mean is zero and the variance is σ ² additive white Gaussian noise.

In the embodiment of the present invention, the signal receiving process includes: receiving the transmitted signal; determining a receiving matrix and a signal-to-noise ratio; and generating a received signal based on the transmitting, the receiving matrix and the signal-to-noise ratio.

Specifically, the signal-to-noise ratio is preset according to the channel, and then the specific expression of the relay to generate the received signal is:

where y ^[r] is the relay received signal, r is the relay node, H ^[N,r] is the channel matrix from user N to relay node r, V _N represents the set of precoding vectors from user i to user j, S _N represents the set of signal vectors sent from user i to user j, and n ^[r] is the signal-to-noise ratio of the relay node r.

At the relay node, the relay node performs linear processing on y ^[r] through the receiving matrix A, namely:

At the relay, the sum signal of the messages sent between the two user pairs can be obtained according to the network coding theory of the physical layer, then the receiving matrix A of the relay needs to be constructed at the relay. Take a ₁ as an example, and take the main network as an example, Signal sent to user 1 and user 2 Put it in the null space of the matrix formed by other channels and cancel the interference, namely:

Other users (users 1 and 3, users 1 and 4, etc.) form the null space of the matrix for sending messages as follows:

Taking the secondary network as an example, the signals sent by user 1 and user 2 are paired The vector is placed in the null space of the other channels forming the matrix and the interference between the other channels is eliminated, namely:

By analogy, the message vector sent between every two users (such as users 1 and 4, users 1 and 6, etc.) is placed in the null space of the matrix formed by other channels to eliminate the interference from other channels, there are:

According to the theory in physical layer network programming, the sum signal of information exchange between two users needs to be obtained at the relay, then the expression of the signal received by the relay can be rewritten as:

In the BC stage, if the relay wants to obtain the required transmission signal, it needs to encode the network, optimize the precoding vector, and then use amplification and forwarding to receive and process the sum signal in the MAC stage. broadcast to each receiver. Then, the interference messages received by each user are eliminated through channel zero-forcing, so that each user only receives messages sent by itself and valid messages that it needs to receive.

Let the transmitted signal of the relay be X _r , namely:

Among them, α is the amplification and forwarding coefficient of the relay. A receiving matrix U of the receiving end is constructed at the receiving end, and the received signal is processed by the receiving matrix U. Taking user 1 of the primary and secondary networks as an example, the signal output processed by user 1 with the receiving matrix is:

where the primary network U ₁ =[v ^[2,1] ,v ^[3,1] v ^[4,1] ...v ^[M,1] ] ^T , the secondary network U ₁ =[v ^[2,1] ,v ^[4,1] ,v ^[6,1] ...v ^[N,1] ] ^T ,

Therefore, the expression of the signal received by the primary and secondary networks is:

S103, the signal receiving end removes the received interference message to obtain a valid signal.

It can be understood that, based on the sum signal, the effective transmission signal is obtained and broadcast. In an implementation manner of the present invention, the effective message received by the user 1 of the main network is:

The valid message received by user 1 of the network is:

The interference messages received by each user are eliminated through channel zero-forcing, so that each user only receives messages sent by itself and valid messages that it needs to receive.

The complexity is an important index used to measure the system performance, through the complexity, we can see the benefit of increasing the spatial multiplexing gain by the number of antennas used. In the method of generalized signal alignment GSA, the zero-forcing algorithm is used to deal with the message interference between users and to configure the antennas of users and relay nodes. According to matrix theory, it can be known that the generalized inversion or singular value decomposition of an m×n matrix A of rank r has a complexity of o(mnr). is an m×n matrix, and the B matrix is an n×p matrix, so its complexity is o(mnp).

The total complexity of the sender at the MAC stage is:

C _T1 =C _T11 +C _T12 =o(M ⁵ +N ⁵ )

In the BC stage, the total complexity of the main network sender is obtained as:

C _T =MC _T1 +C _T2 =o(M ⁶ +N ⁵ )

In the MAC stage, the receiver is the relay node, and the linear precoding of the relay node is realized by multiplying the channel matrix and the beamforming vector matrix. The total complexity of the relay node is:

o _R1 =o(M ⁵ +N ⁵ )

The total complexity in the BC phase is:

o _R21 =o(M ⁵ +N ⁵ )

The complexity of the secondary network receiver is:

o _R22 = o(N ⁵ )

The total complexity of the BC stage is obtained by substituting and processing the formula C = C _T + C _R :

C=C ^T +C ^R =o(M ⁶ +N ⁵ )

In the present invention, all channels are assumed to be perfect channels, that is, non-Rayleigh fading channels, and the transmitting end needs to meet the power restriction condition, assuming that its transmit power is P, so that each user obtains the same noise variance and is σ ² . In the BC phase, after the message sent by the relay node to each user is processed, the received signal-to-noise ratio and rate of each valid message of user i are:

R _j =log ₂ (1+SINR _j )

To sum up, in the embodiment of the present invention, in a multi-user wireless communication network, due to interference caused by simultaneous transmission of multiple source nodes, data efficiency will drop sharply. Taking the main network as the Y channel and the secondary network as the X channel, the bidirectional single-relay node of the coexisting network is the system model diagram. According to the physical layer network coding technology under the generalized signal alignment, the model diagram of the primary and secondary networks with any number of users can be obtained. A scheme to improve network multiplexing gain and improve system performance is proposed.

First, based on the fact that each node has global channel state information that remains unchanged, and the node operates in half-duplex mode, it is assumed that the relay node has Nr antennas, each user has Nt antennas, and sends M-1 antennas. independent news. The whole process consumes 2 time slots: the uplink (MAC) phase and the downlink (BC) phase. The signal sent by the i-th user on the left to the j-th user on the right is denoted as S ^[i,j] . Then in the MAC stage, all nodes send messages to the relay node, and the relay node will receive a total of M(M-1)+N·N/2 independent signals from the primary and secondary networks. The information sent by each user of the main network is pre-coded to generate a transmission signal, all signals are pre-coded and then sent to the relay node, the relay node generates the received signal, and the relay node performs linear linearity on the received signal generated at the relay node through the acceptance matrix. Process get and signal. Then, the sum signal obtained at the relay node is subjected to physical layer network coding, and then precoding processing is performed to obtain the signal sent by the relay node. Finally, the message processed by the relay node is broadcast to all users by amplifying and forwarding in the BC stage. Therefore, by applying the embodiments of the present invention, compared with the traditional single-relay node bidirectional single network, the present invention studies the physical layer network coding with the generalized signal alignment algorithm of the coexisting channel relay node network model, and analyzes the two modified generalized signal alignment algorithms. The complexity of the signal alignment algorithm is calculated, and the sum rate of the system under the generalized signal alignment algorithm is calculated. The analysis shows that the generalized signal alignment algorithm has the advantage of improving the system performance.

The above-mentioned embodiments merely illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed in the present invention should still be covered by the claims of the present invention.

Claims (5)

1. A communication method based on signal space alignment, wherein in a primary network, for any user M, the number of information transmitted by the user M is M x (M-1), and in a secondary network, for any user N, the number of information transmitted by the user N is N/2, where M is greater than or equal to 3 and N is greater than or equal to 4, in the primary network, information can be transmitted and received for any user, and in the secondary network, only signal transmission can be performed for any user in 2N, and only signal reception can be performed for any user in 2N-1, the method comprising:

each user generates a sending signal by coding information to be sent, and sends the sending signal to a relay node;

performing in the relay node: receiving the sending signal and generating a receiving signal, and coding the receiving signal to obtain a sum signal;

and the signal receiving end eliminates the received interference message to obtain an effective signal.

2. The communication method according to claim 1, wherein the step of receiving the transmission signal and generating a reception signal comprises:

receiving the transmission signal;

determining a receiving matrix and a signal-to-noise ratio;

generating a received signal based on the transmit receive matrix and the signal-to-noise ratio.

3. The method of claim 2, wherein the generating the received signal is embodied as:

wherein, y^[r]For receiving signals, r is a relay node, N is the number of users, H^[N,r]Channel matrix, V, from user N to relay node r_NSet of precoding vectors, S, from user i to user j_NIs a set of signal vectors transmitted by users i to j, n^[r]Is the signal-to-noise ratio of the relay node r.

4. The method of claim 3, wherein the sum signal is expressed as:

wherein M is the number of main network users, N is the number of sub-network users, s_M,M-1For user M and user M-1.

5. The communication method according to claim 4, wherein the specific representation of the valid signal comprises:

wherein,for the main network to be active, the network,is a sub-net effective signal, u₁Receiving matrix, n, on behalf of primary network users 1₁Signal noise, U, representative of primary network subscriber 1₁A receiving matrix representing the secondary network users 1,representing the noise of the secondary network user 1.