CN108306663B - Simple network coding system and method based on MIMO Y channel physical layer - Google Patents

Abstract

The invention discloses a physical channel based on MIMO Y channelIn a two-hop, multi-user and multi-antenna MIMO Y channel, there are one and only one Relay node Relay with N antennas, and there are K Relay nodes Relay with M antennas_iMutual information User node User of antenna_iK, K,; all communication is realized through Relay, the communication is represented in two channels, a multi-user access channel is recorded as MAC, and a broadcast channel is recorded as BC; in MAC, all User nodes User_iTransmitting the information to a Relay; in BC, Relay sends re-encoded information to User_i(ii) a In the process of forwarding MAC to BC, Relay realizes communication through network coding conversion based on a mutual information relation matrix, a global channel information matrix and a user node precoding and decoding rule appointed by a system. The invention provides a simple physical layer precoding matrix V for users_iGenerating a regular, simple physical layer decoding matrix W_iGenerating rules, a simple transform coding matrix F rule from the MAC stage to the BC stage.

Description

Simple network coding system and method based on MIMO Y channel physical layer

Technical Field

The invention belongs to the technical field of wireless communication, and relates to a simple network coding system and method for a MIMO Y channel physical layer in multi-user, multi-antenna and two-hop wireless communication.

Technical Field

The multi-antenna, multi-hop and multi-user wireless network is an important supplement to the current commercial organized network, and is also one of the important deployment forms of the next generation wireless access networks such as the Internet of things, the sensor network, the family heterogeneous network and the like. A multi-user wireless network, which is a basic form of current commercial network deployment; the multi-antenna property is derived from an important means for improving the anti-interference capability of the user node. Therefore, the multi-hop network based on multiple users and multiple antennas is also the focus of research on the next generation wireless network deployment form. However, there are still many technical difficulties. The main difficulty is the implementation of the communication freedom in a multi-user wireless communication network. Current multi-user wireless communication systems are still interference limited. In addition, in the unorganized network, the utilization efficiency of the communication resources is greatly reduced without coordination of the central node. The difficulty point is how to quickly and simply acquire the multi-user communication freedom degree as much as possible at lower communication cost. Although some current research indicates that in theory MIMO Y channels, maximum degrees of freedom can be achieved. The Relay node based on the MIMO Y channel has the characteristics of organizing the network, is flexible with the Relay node in the meta-organization network, and has the capability of fully utilizing all the acquired channel information. And realizing the interference alignment idea, namely eliminating the interference among users.

There are two kinds of nodes in MIMO Y channel system, one Relay node is marked as Relay, and K User nodes are marked as User_iI is 1, …, K. The MIMO Y channel has two basic states, a multiple access state, denoted MAC, and a broadcast state, denoted BC. All communication is effected via a unique Relay, in the MAC all User nodes User_iK passes the information to Relay, i 1, …; in BC, Relay sends re-encoded information to User_i，i＝1,…,K。

However, although the current research based on MIMO Y channel suggests the possibility of maximum communication freedom acquisition, no practical operability method can be proposed. Moreover, the research conclusion is based on the realization of the local interference alignment idea, the consideration of (operation) characteristics of a global system is omitted, and the global channel information condition is not considered, so that the assumptions can not be realized at all and are not perfect.

Disclosure of Invention

In order to solve the technical problem, the invention provides a simple network coding system and method based on a MIMO Y channel physical layer in multi-user, multi-antenna and multi-hop wireless communication.

The technical scheme adopted by the system of the invention is as follows: a simple network coding system based on MIMO Y channel physical layer is characterized in that: in a two-hop, multi-user and multi-antenna MIMO Y channel, there is one and only one Relay node Relay with N antennas, and there are K Relay nodes with M_iMutual information User node User of antenna_iI is 1, …, K; all communication is realized through Relay, communicationThe method is characterized in that the method comprises two channels, namely a multi-user access channel which is marked as MAC, and a broadcast channel which is marked as BC; in MAC, all User nodes User_iTransmitting the information to a Relay; in BC, Relay sends re-encoded information to User_i(ii) a In the process of forwarding MAC to BC, Relay realizes communication through network coding conversion based on a mutual information relation matrix, global channel information and a global coding and precoding generation rule.

The method adopts the technical scheme that: a simple network coding method based on MIMO Y channel physical layer includes that in a two-hop, multi-user and multi-antenna MIMO Y channel, there is one and only one Relay node Relay with N antennas, there are K Relay nodes with M_iMutual information User node User of root antenna_iI is 1, …, K; all communication is realized through Relay, and the communication is represented in two channels, one is a multi-user access channel and recorded as MAC, and the other is a broadcast channel and recorded as BC;

characterized in that the method comprises the following steps: step 1: in the MAC stage, a user carries out network precoding;

the specific implementation comprises the following substeps:

step 1.1: obtaining all channel information estimation through training sequence and Relay, obtaining system physical layer mutual information relation matrix A, and optimizing pre-coding and decoding rule f_1.2And f_3.1(ii) a And distributes A and the preferred codec rule f_1.2、f_3.1Giving all users; when the network topology is not changed and the pre-coding and decoding rules are not changed, the initialization step 1.1 is only used for the first operation; user_iThe channel estimation training sequence can be carried and finished at the MAC and BC stages;

step 1.2: user_iAccording to a physical layer mutual information relation matrix A issued by Relay, utilizing a predetermined optimized coding rule function f_1.2A and User_iCorresponding unique node position number m in A_iAs a parameter, a global precoding matrix V thereof is obtained_i，V_i←f_1.2(A,m_i)；

Step 1.3: user_iAccording to the pre-determinedCoding matrix V_iAnd User_iInformation to be sent to all other users

Generating a precoded global information matrix X_i＝V_iS_i(ii) a Wherein

Means the ith User_iPrepared for all other users sigma except i_iThe information sent;

step 1.4: in the MAC channel, all users_iI 1, …, K, clocking each X at a uniform time_iSending to a Relay;

step 2: in the conversion from the MAC stage to the BC stage, the Relay performs global network recoding;

the specific implementation comprises the following substeps:

step 2.1: relay receives X sent by all users_iChannel-transformed superposition output Y_RI.e. by

Wherein H_i,RFrom the ith User_iChannel gain of Relay to Relay node.

Step 2.2: relay estimates all channel information including MAC global channel information H according to the obtained information_Σ,RGlobal channel information H of BC channel_R,ΣA system physical layer mutual information relation matrix A, and a preferred pre-coding and decoding rule f_1.2And f_3.1Generating V_i←f_1.2(A,m_i) I ═ 1, …, K, compute Relay mutual information encoding conversion matrix F ← F_2.1(A,f_1.2,H_Σ,R,H_R,Σ)；

Step 2.3: based on the Relay mutual information transcoding matrix F, via the information V received from the MA channel_RGenerating broadcast information X_R＝FY_RAnd broadcasting information X on the BC channel_R；

And step 3: in the BC stageThe User generates a global receiving decoding matrix according to a network coding decoding matrix generation rule and obtains all nodes to send to the User_iInformation estimation of

The specific implementation comprises the following substeps:

step 3.1: user_iAccording to a system physical layer mutual information relation matrix A and a decoding rule f issued by Relay_3.1Forming a global receive decoding matrix W_i←f_3.1(A,m_i) (ii) a Wherein m is_iIs User_iA corresponding unique node location number in a;

step 3.2: user_iBased on W_iDecoding received X_RSamples are obtained, and other users are given to the User_iInformation estimation

The method presence criteria are:

and

(ii) present; wherein P is⁺The representation is the generalized inverse of the matrix P;

corresponding to the users with the same description order as the physical layer mutual information relation matrix A of the system, and a global receiving decoding matrix W_iA diagonal matrix formed by the sequences;

corresponding to the users with the same description sequence as the physical layer mutual information relation matrix A of the system, and a global precoding matrix V_iA diagonal matrix formed by the sequences; h_R,Σ，H_Σ,RBC and MAC global channel information matrices, respectively.

Preferably, F ← F_2.1(A,f_1.2,H_∑,R,H_R,∑) The calculation rule is as follows:

compared with the prior art, the method of the invention has the following advantages and beneficial effects:

(1) the invention is based on the global mutual information relation matrix A and the coding and decoding design of the global channel information, so the invention has very strong operability and does not have the problem of being inoperable in mathematical computation due to the local design;

(2) in the invention, at the user side, the channel information characteristics do not need to be known, only the precoding is carried out based on the global mutual information relation matrix A, and the precoding and decoding are carried out with the optimal coding and decoding design rule of the system, so the operation is simple and easy, and the requirement on the node capacity is also reduced;

(3) on the Relay side, a channel matrix can be obtained through a training sequence, the coding is carried out based on a global mutual information relation matrix A and the coding and decoding design rule optimized in the whole system, and then information conversion matrix coding can be obtained, so that the operation steps are simplified;

(4) the invention realizes simple physical layer network coding based on the actual condition;

(5) explicitly giving the code presence conditions, and the coding rules, including F, V_i，W_i；

(6) The coding and decoding rules optimize a sufficient optimization space for the system, are compatible with other coding methods, and only need to meet basic rules.

Drawings

FIG. 1 is a system architecture diagram of an embodiment of the present invention;

FIG. 2 is a flow chart of a method according to an embodiment of the present invention.

Detailed Description

In order to facilitate the understanding and implementation of the present invention for those of ordinary skill in the art, the present invention is further described in detail with reference to the accompanying drawings and examples, it is to be understood that the embodiments described herein are merely illustrative and explanatory of the present invention and are not restrictive thereof.

Referring to fig. 1, the simple network coding system based on the MIMO Y channel physical layer provided by the present invention assumes that the channel is estimated by perfectly utilizing the MAC and BC channels and the training sequence information, and has (better) ideal channel estimation, for example, under the condition of relatively good SNR condition; the whole coding is divided into three stages, namely an MAC pre-coding stage, a Relay network coding stage and a BC decoding stage, which are respectively abbreviated as MAC, NC and BC stages. Three-stage communication is alternately carried out according to the time sequence of MAC, NC and BC; the system allows full-duplex communication, and allows multiple communication cycles of MAC, NC and BC to coexist according to the same or different time beats in different independent or mixed divisions of different channels such as different time divisions, frequency divisions, space divisions and the like; in the MAC stage of the system, all User nodes, User_i(i-1, …, K) pair transmission information

Using precoding matrices V_iPrecoding to obtain X_iAnd according to the same time beat, the coded information X is_iSending to a Relay node Relay to be converged into Y_R(ii) a In the conversion from the MAC stage to the BC stage, the Relay node pair of the system receives the information Y_RAccording to the global channel information and all preset precoding matrixes V_iGenerating a recoding matrix F by pairing F with Y_RGenerating X by network coding recoding_R(ii) a After the NC phase, the BC phase of the system is entered, and in the BC phase, the Relay broadcast data Y_RUser of each User node_iReceiving the information of the user, and the user follows the precoding matrix V_iInformation, generating a reception decoding matrix W_iAnd decoding the received information to complete one-time complete independent communication. The invention mainly lies in that F, V are paired based on the channel model of the system, namely the MIMO Y channel model_i，W_iInnovation of construction theory and practice.

To elaborate the examples, the present embodiment uses a more refined systematic symbologyThe following were used: the Relay is provided with N antennas and K users, and each user is provided with K-1 antennas; v_iIs represented as V^[i,j]Represents a slave User_iPoint to User_jThe precoding matrix of (a); s^[i,j]To represent

User of slave User_iUser pointing_jThe information of (a); y is^[Σ,R]The information that all K users send to the Relay and are received by the Relay is represented; i.e. superscript [ A, B]Representing parameters emanating from A with a target of B, sigma representing all users, sigma_iIndicating removal of User_iAll users except R, R represents Relay; other H denotes channel information, for the same reason H^[Σ,R]Indicating that K users send Relay global channel information, i.e. the aforementioned H_Σ,R(ii) a F denotes slave Y executed by Relay^[Σ,R]To X^[R,Σ]The transformation matrix of (2); m denotes a decoding matrix, W^[i,j]Representing decoding from User_iPoint to User_jA decoding matrix of the information of (1). A is a global mutual information relation matrix.

Referring to fig. 2, the simple network coding method for achieving interference alignment based on the MIMO Y channel physical layer provided by the present invention includes three major steps, 9 minor steps.

Step 1: in the MAC stage, a user carries out network precoding;

step 1.1: obtaining all channel information estimation through a training sequence and Relay, obtaining a system physical layer mutual information relation matrix A, and distributing A to all users; simultaneously distributing optimized pre-coding and decoding rules f meeting the conditions_1.2And f_3.1. When the network topology is not changed and the pre-coding and decoding rules are not changed, the initialization step 1.1 is only used for the first operation; user_iThe channel estimation training sequence can be carried and finished at the MAC and BC stages; since the channel estimation is a mature method, it is not described herein any more, and it is only assumed that the corresponding channel information matrix is obtained by the corresponding method. For example, when information conditions are ideal, such as high SNR, K is used to mutually communicate with other K-1 users via the MIMO Y channel,

at this time, the channel change operation

Is equivalent to that of

Change to

Direct operation of (2); i.e. equivalent to operation

Wherein 0_1×(K-1)Representing a row-1 (K-1) column zero matrix. This cost operation is the system physical layer mutual information relationship matrix, namely:

this is an assumption under ideal conditions, when the channel is perfect, antenna M_iNot uniquely determined, but still determined according to the actual mapping relation

To

The equivalent mapping relationship a of (a) is only different in form.

Step 1.2: user_iAccording to a physical layer mutual information relation matrix A issued by Relay, utilizing a predetermined optimized coding rule function f_1.2A and User_iCorresponding unique node position number m in A_iAs a parameter, a global precoding matrix V thereof is obtained_i，V_i←f_1.2(A,m_i) (ii) a Here, as an example, let m_iI; is provided with

Therefore, it is only necessary to set the condition

And (4) finishing. Specific form requirement

I.e. without amplifying the original signal power. For example, it is possible to set

When the ideal assumption is that there are K-1 antennas per user, each antenna corresponding to one user transmission, and space-time coding is not taken into account. When the system has other space-time coding requirements, only the space-time code requirements and the setting requirements need to be combined. The ideal assumption is similar, except that the structure needs to be set according to the antenna relationship, rather than the ideal square matrix structure.

Step 1.3: user_iPrecoding matrix V according to each useful information_iI.e. by

A precoding vector for each individual mutual information is generated, and, based on the transmitted information,

s^[i,j]the middle i is not equal to j, and a pre-coded global information matrix X is generated_iI.e. by

Step 1.4: in the MAC channel, all users_iSending coded global information according to uniform time beat

To Relay;

step 2: in the conversion from the MAC stage to the BC stage, the Relay performs global network recoding;

step 2.1: relay receives X sent by all users_iI is 1, …, K, wherein

To obtain

Step 2.2: relay estimates all channel information including MAC global channel information H according to the obtained information_Σ,RGlobal channel information H of BC channel_R,ΣA system physical layer mutual information relation matrix A, and a preferred pre-coding and decoding rule f_1.2And f_3.1Generating V_i←f_1.2(A,m_i) I ═ 1, …, K, compute Relay mutual information encoding conversion matrix F ← F_2.1(A,f_1.2,H_Σ,R,H_R,Σ)；

Order to

According to the assumption, let

With F ═ BH (BH)^[R,Σ])⁺(H^[Σ,R]B^T)⁺Wherein (BH)^[R,Σ])⁺Indicating BH of^[R,Σ]A generalized inverse matrix, when the generalized inverse matrix does not exist, the encoding is not established;

step 2.3: based on the Relay mutual information code conversion matrix F ═ (BH)^[R,Σ])⁺(H^[Σ,R]B^T)⁺By information received from the MA channel, i.e.

Generating broadcast information, X, for the BC stage^[R,Σ]＝FY^[Σ,R]And sending;

and step 3: in BC stage, User carries out rule and method for generating network coding and decoding matrix, and obtains all nodes to send to User_iInformation estimation of

Step 3.1: the user decodes the rule f according to the physical layer information A issued by the Relay_3.1Forming a system global receive decoding matrix, i.e., in this case

Step 3.2: user_iBased on W_iDecoding and received X_RSamples, i.e. codes Y^[R,i]＝H^[R,i]X^[R,Σ]+ N, then decoded to obtain

The existence criteria of the method of the invention are: :

and

are present. Wherein P is⁺The representation is the generalized inverse of the matrix P;

corresponding to the users with the same description order as the physical layer mutual information relation matrix A of the system, and a global receiving decoding matrix W_iA diagonal matrix formed by the sequences;

corresponding to the users with the same description sequence as the physical layer mutual information relation matrix A of the system, and a global precoding matrix V_iA diagonal matrix formed by the sequences; h_R,Σ，H_Σ,RBC and MAC global channel information matrices, respectively.

All the above coding is performed under the following criteria:

User_ithe precoding matrix and the receive decoding criteria of (a) are:

wherein A is the system physical layer mutual information relation matrix,

is a user global receiving decoding matrix W in the same order as the description of A_iA diagonal matrix formed by the sequences;

is the user global reception precoding matrix V in the same order as the description of A_iA diagonal matrix formed by the sequences; function V_i←f_1.2(A,i)，W_i←f_3.1(A, i) must satisfy the above rule.

F←f_2.1(A,f_1.2,H_∑,R,H_R,∑) The calculation rule of (1) is:

the invention is based on MIMO Y channel system, and can realize the following assumed conditions: there is a (better) ideal channel estimate, e.g. in case of better SNR conditions; all users have the same number of antennas and mutual information relationship protocol (step 1.1). By fully utilizing the global channel information, an operable MIMO Y-channel network coding method is provided. The method is mainly characterized in that the design is based on realizable hypothesis and a global mutual information relation matrix, a simple physical layer precoding matrix generation rule is provided for a user in an MAC stage, a simple physical layer decoding matrix generation rule is provided for the user in a BC stage, a simple conversion coding matrix F rule from the MAC stage to the BC stage is provided for Relay, and a corresponding system operation rule.

It should be understood that parts of the specification not set forth in detail are well within the prior art.

It should be understood that the above description of the preferred embodiments is given for clarity and not for any purpose of limitation, and that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (2)

1. A simple network coding method based on MIMO Y channel physical layer, adopt and base on MIMO Y channel physical layer simple network coding system;

the method is characterized in that: the system has one and only one Relay node Relay of N antennas in a two-hop, multi-user and multi-antenna MIMO Y channel, and has K Relay nodes of M_iMutual information User node User of antenna_iK, K,; all communication is realized through Relay, and the communication is represented in two channels, one is a multi-user access channel and recorded as MAC, and the other is a broadcast channel and recorded as BC; in MAC, all User nodes User_iTransmitting the information to a Relay; in BC, Relay sends re-encoded information to User_i(ii) a In the process of forwarding MAC to BC, Relay realizes communication through network coding conversion based on a mutual information relation matrix, a global channel information matrix and a user node precoding and decoding rule appointed by a system;

the method comprises the following steps:

step 1: in the MAC stage, a user carries out network precoding;

the specific implementation comprises the following substeps:

step 1.1: obtaining all channel information estimation through training sequence and Relay, obtaining system physical layer mutual information relation matrix A, and pre-coding and decoding rule f_1.2And f_3.1(ii) a And distribute A and codec rules f_1.2、f_3.1Giving all users; when the network topology is not changed and the pre-coding and decoding rules are not changed, the initialization step 1.1 is only used for the first operation; user_iThe channel estimation training sequence is selected to be carried and finished in the stages of MAC and BC;

step 1.2: user_iAccording to a physical layer mutual information relation matrix A issued by Relay, utilizing a predetermined optimized coding rule function f_1.2，AAnd User_iCorresponding unique node position number m in A_iAs a parameter, a global precoding matrix V thereof is obtained_i，V_i←f_1.2(A，m_i)；

Step 1.3: user_iAccording to its precoding matrix V_iAnd User_iInformation to be sent to all other users

Generating a precoded global information matrix X_i＝V_iS_i(ii) a Wherein

Means the ith User_iPrepared for all users other than i ∑_iThe information sent;

step 1.4: in the MAC channel, all users_iK, clocking each x at a uniform time_iSending to a Relay;

step 2: in the conversion from the MAC stage to the BC stage, the Relay performs global network recoding;

the specific implementation comprises the following substeps:

step 2.1: relay receives X sent by all users_iChannel-transformed superposition output Y_RI.e. by

Wherein H_i，RFrom the ith User_iChannel gain of Relay to Relay node;

step 2.2: relay estimates all channel information including MAC global channel information H according to the obtained information_∑，RGlobal channel information H of BC channel_R，∑A system physical layer mutual information relation matrix A, and a pre-coding and decoding rule f_1.2And f_3.1Generating V_i←f_1.2(A，m_i) I ═ 1, …, K, compute Relay mutual information encoding conversion matrix F ← F_2.1(A，f_1.2，H_∑，R，H_R，∑)；

Step 2.3: based on the Relay mutual information transcoding matrix F, via the information Y received from the MA channel_RGenerating broadcast information X_R＝FY_RAnd broadcasting information X on the BC channel_R；

And step 3: in the BC stage, the User generates a global receiving decoding matrix according to a network coding decoding matrix generation rule, and obtains all nodes to send to the User_iInformation estimation of

The specific implementation comprises the following substeps:

step 3.1: user_iAccording to a system physical layer mutual information relation matrix A and a decoding rule f issued by Relay_3.1Forming a global receive decoding matrix W_i←f_3.1(A，m_i) (ii) a Wherein m is_iIs User_iA corresponding unique node location number in a;

step 3.2: user_iBased on W_iDecoding received X_RSamples are obtained, and other users are given to the User_iInformation estimation

2. The method of claim 1, wherein F ← F_2.1(A，f_1.2，H_∑，R，H_R，∑) The calculation rule is as follows:

the method presence criteria are:

and

(ii) present; wherein P is⁺The representation is the generalized inverse of the matrix P;

corresponding to the users with the same description order as the physical layer mutual information relation matrix A of the system, and a global receiving decoding matrix W_iA diagonal matrix formed by the sequences;

corresponding to the users with the same description sequence as the physical layer mutual information relation matrix A of the system, and a global precoding matrix V_iA diagonal matrix formed by the sequences; h_R,Σ，H_Σ,RBC and MAC global channel information matrices, respectively.

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