CN101977103A - Implementation method of equivalent full duplex in bidirectional relay network - Google Patents

Abstract

The invention discloses an equivalent full-duplex realization method in a two-way relay network. By applying the embodiment of the invention, through efficient relay cooperation, starting from the number of time slots prepared, the relay nodes participating in the cooperation in each hop are always only One is in the sending state, and the rest are in the receiving state. The embodiment of the present invention utilizes alternate transmission and reception between relay nodes to realize an equivalent full-duplex bidirectional relay network, improve network resource utilization, and maximize spectrum efficiency.

Description

A Realization Method of Equivalent Full Duplex in Bidirectional Relay Network

technical field

The invention relates to the technical field of cooperative communication in a broad sense, in particular to a method and device for realizing equivalent full duplex in a two-way relay network.

Background technique

In CoMP communication, multi-hop communication, time-division multiplexing of two-way channels, and half-duplex working mode of nodes are the three dominant factors leading to low spectrum efficiency of two-way relay channels. Existing methods for improving the spectral efficiency of two-way relay channels include:

(1) The relay node processes two-way data at the same time purely in a decode-forward (DF) manner (that is, after decoding the two-way data separately, the network coding method is adopted);

(2) The relay node uses denoising mapping to process bidirectional data (that is, physical layer network coding);

(3) The relay node simultaneously processes bidirectional data in an amplify-and-forward (AF) manner (that is, bidirectional throughput-enhanced relay in the amplify-and-forward manner).

Although the existing method can improve the spectral efficiency of the two-way relay channel to a certain extent, it can only compensate the loss of system spectral efficiency caused by the time division multiplexing of the two-way channel. In the wireless two-way relay channel model of the node half-duplex mode However, the application of the above three methods still cannot ensure that the destination node receives information in every time slot. Therefore, the spectral efficiency of the two-way relay channel is still low, and there is still a lot of room for improvement.

Contents of the invention

The present invention provides an equivalent full-duplex realization method in a two-way relay network. The destination node can receive information in each time slot after the number of time slots is prepared, thereby maximizing spectrum efficiency.

The present invention provides an equivalent full-duplex implementation method in a two-way relay network. The first group of nodes (S1, D1) and the second group of nodes (S2, D2) that exist in the space are set, and the nodes S1 and S2 are always In the sending state, the node D1 and the node D2 are always in the receiving state, and there is no direct link between the node S1 to the node D2, and the node S2 to the node D1, the first group of nodes (S1, D1) and the second Two groups of nodes (S2, D2) realize information exchange through at least one group of relay nodes; the method also includes:

In the first time slot of sending data, the nodes S1 and S2 send data, and the nodes in the relay group are in the receiving state; the relay nodes in the receiving state complete the physical layer network coding operation;

Starting from the second time slot of sending data, in each time slot of sending data, select a relay node from the relay nodes in the receiving state as the sending node, and the rest of the nodes in the relay group are in the receiving state; in the receiving state The relay node in the state completes the physical layer network coding operation;

Starting from the number of preparation time slots, in each data sending time slot, only one relay node is always in the sending state among the assisting relay nodes, and the rest are in the receiving state.

Wherein, the number of preparation time slots is determined according to the number of hops between the first group of nodes and the second group of nodes.

Wherein, the determination of the number of preparation time slots according to the number of hops between the first group of nodes and the second group of nodes specifically includes: the number of preparation time slots is equal to that of the first group of nodes and the second group of nodes after the communication is initiated. The number of hops between nodes.

Wherein, an optimal relay node is selected from all the relay nodes in the receiving state in the last time slot according to the optimal path selection algorithm to switch to the sending state.

There are multiple actual transmission models for each time slot, and the specific number is the number of relay nodes participating in forwarding in each group.

Wherein, the nodes S1 and S2 both send a new data packet every time slot; or, send network coding data every time slot, and the network coding data is the network coding data of the new data packet and the received data packet.

Wherein, the data sent by the relay node in the sending state is the data after the two-way data stream has been encoded by the network.

By applying the embodiment of the present invention, through efficient relay cooperation, starting from the number of preparation time slots, only one relay node participating in the cooperation of each hop is always in the sending state, and the rest are in the receiving state. The embodiment of the present invention utilizes alternate transmission and reception between relay nodes to realize an equivalent full-duplex bidirectional relay network, improve network resource utilization, and maximize spectrum efficiency.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings without making creative efforts.

Fig. 1 is a flow chart of an equivalent full-duplex implementation method in a two-hop bidirectional relay network according to an embodiment of the present invention;

Fig. 2 is a schematic diagram showing the realization of the space between the first and second groups of nodes with 2 hops and 3 relay nodes in each hop according to an embodiment of the present invention;

Fig. 3 is the synoptic diagram that carries out PNC operation to the signal of path i based on the embodiment shown in Fig. 2;

Fig. 4 is all possible system models based on the first two time slots of the embodiment shown in Fig. 2;

Fig. 5 is a schematic diagram showing the realization of the space between the first and second groups of nodes with 3 hops and the number of relay nodes in each hop being 2 according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of the realization of the first and second groups of nodes with 4 hops between the first and second groups of nodes in space according to an embodiment of the present invention, and when the number of relay nodes in each hop is 3;

Fig. 7 is a schematic diagram of implementation when there are 5 hops between the first group and the second group of nodes where space exists according to an embodiment of the present invention, and the number of relay nodes in each hop is 3.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

In the embodiment of the present invention, multiple half-duplex nodes use physical layer network coding to process multi-channel data during the mutual cooperative relay process, and select the "optimal" path through time-division alternate transmission and channel state information. , which can realize the resource utilization rate of an equivalent full-duplex two-way relay network, and effectively improve the spectrum efficiency of the two-way relay channel.

Referring to FIG. 1 , it is a flow chart of an equivalent full-duplex implementation method in a two-hop bidirectional relay network according to an embodiment of the present invention. In this embodiment, the first group of nodes (S1, D1) and the first group of nodes (S1, D1) and Two groups of nodes (S2, D2), node S1 and node S2 are always in the sending state, node D1 and node D2 are always in the receiving state, and there is no direct link between node S1 to node D2, node S2 to node D1, that is That is, information exchange is realized between the first group of nodes (S1, D1) and the second group of nodes (S2, D2) through at least one group of relay nodes (relay nodes used for each hop are called a group); Nodes S1 and D1, S2 and D2 are relatively close to each other, that is to say, nodes S1 and D1, S2 and D2 can realize data sharing in a certain way if there is a direct link; the method also includes:

Step 101, in the first time slot of sending data, node S1 and node S2 send data, and the nodes in the relay group are in the receiving state; the relay nodes in the receiving state complete the physical layer network coding operation;

Step 102, starting from the second time slot for sending data, in each time slot for sending data, select a relay node from the relay nodes in the receiving state as the sending node, and the rest of the nodes in the relay group are in the receiving state ;The relay node in the receiving state completes the physical layer network coding operation;

Step 103, starting from the number of preparation time slots, in each time slot for sending data, only one relay node is always in the sending state among the relay nodes participating in the assistance, and the rest are in the receiving state.

The above number of preparation time slots is determined according to the number of hops between the first group of nodes and the second group of nodes; specifically, the number of preparation time slots is equal to the distance between the first group of nodes and the second group of nodes after the communication is initiated. hop count. For example, if there are 2 hops between the first group of nodes and the second group of nodes, then the number of preparation time slots is 2; if there are 3 hops between the first group of nodes and the second group of nodes, then the number of preparation time slots is 3.

It should be noted that, according to the optimal path selection algorithm, an optimal relay node is selected from all relay nodes in the receiving state in the previous time slot to switch to the sending state.

It should be noted that there are multiple actual transmission models for each time slot, and the specific number is the number of relay nodes participating in forwarding in each group.

It should be noted that the nodes S1 and S2 can both send a new data packet every time slot; they can also send the network coding data containing the new data packet every time slot.

It should be noted that the two-way data flow converges at the relay node located at the "relative center" of the network, and continues to relay and forward after network coding; There is a relay node located at the absolute center, so "relative center" is used to indicate the location where bidirectional data intersection occurs. Therefore, the data sent by the relay node in the sending state is the data after the bidirectional data flow is encoded by the network.

By applying the embodiment of the present invention, through efficient relay cooperation, starting from the number of preparation time slots, only one relay node participating in the cooperation of each hop is always in the sending state, and the rest are in the receiving state. The embodiment of the present invention utilizes alternate transmission and reception between relay nodes to realize an equivalent full-duplex bidirectional relay network, improve network resource utilization, and maximize spectrum efficiency.

Taking 2-5 jumps as an example below, the present invention will be described in detail.

Referring to FIG. 2 , it is a schematic diagram of realization of two hops between the first and second groups of nodes that exist in space according to an embodiment of the present invention.

(1) In the first time slot of sending data, all relay nodes receive bidirectional data from two source nodes S1 and S2 at the same time, and implement the physical layer of two-way signals according to appropriate demodulation mapping rules such as MAP mapping rules Network coding (PNC, Physical-Layer Network Coding) operation; at this time, the nodes in the relay group are all in the receiving state;

(2) From the second time slot, the relay node in the receiving state receives the superposition of the 3-way signals from the two source nodes and the relay node in the sending state, and completes the PNC operation of the 3-way signals; and , each time slot selects the "optimal" relay node from all the relay nodes in the receiving state in the previous time slot according to the "optimal" path selection algorithm to switch to the sending state, and the latest received "encoding" The information is forwarded to the next hop, and the relay node in the sending state changes to the receiving state in the subsequent time slot.

When the number of relay nodes is n=3, the specific implementation process is as follows:

Considering the quasi-static fading channel, all nodes work in half-duplex state. The data packets sent by the source nodes S1 and S2 in the jth time slot are

表示源节点i在第j个时隙和第j-1个时隙发送数据的模2加运算。in,

Indicates the modulo 2 addition operation of the source node i sending data in the jth time slot and the j-1th time slot.

From the second time slot, the relay node in the receiving state receives the superposition of the 3-way signals from the two source nodes S1 and S2 and the relay node in the sending state, and completes the PNC operation of the 3-way signals. The received signal of the relay node R _m in the receiving state is:

${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}<span\; class="notranslate">\; =</span>\sqrt{\mathrm{<span\; class="notranslate">\; P</span>}}{<span\; class="notranslate">\; \&PartialD;</span>}_{{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="m\; x\; S"\; filenames="HDA0000030479640000031.png,HDA0000030479640000041.png"\; state="\{\{state\}\}">m</figure-callout></span><figure-callout\; id="1"\; label="m\; x\; S"\; filenames="HDA0000030479640000031.png,HDA0000030479640000041.png"\; state="\{\{state\}\}">\; </figure-callout>}}}{\mathrm{<span\; class="notranslate">\; x</span>}}_{{}_{}}{{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}_{}<span\; class="notranslate">\; +</span>\sqrt{\mathrm{<span\; class="notranslate">\; P</span>}}{<span\; class="notranslate">\; \&PartialD;</span>}_{{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="m\; x\; S"\; filenames="HDA0000030479640000031.png,HDA0000030479640000041.png"\; state="\{\{state\}\}">m</figure-callout></span><figure-callout\; id="2"\; label="m\; x\; S"\; filenames="HDA0000030479640000031.png,HDA0000030479640000041.png"\; state="\{\{state\}\}">\; </figure-callout>}}}{\mathrm{<span\; class="notranslate">\; x</span>}}_{{}_{}}{{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}_{}<span\; class="notranslate">\; +</span>\sqrt{\mathrm{<span\; class="notranslate">\; P</span>}}{<span\; class="notranslate">\; \&PartialD;</span>}_{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{\mathrm{<span\; class="notranslate">\; x</span>}}_{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}$

为中继节点R_m处的加性高斯白噪声，均值为0，方差为N₀/2，N₀表示噪声功率。

表示信道的衰落特征，服从均值为0，方差为σ²的瑞利分布。Where P is the node transmit power, x _v represents the unit power modulation symbol of node v, v∈{S ₁ , S ₂ , R _t }, t∈{1, 2, 3};

is the additive white Gaussian noise at the relay node R _m , with a mean of 0 and a variance of N ₀ /2, where N ₀ represents the noise power.

Represents the fading characteristics of the channel, obeying the Rayleigh distribution with mean value 0 and variance σ ² .

向下一跳转发，处于发送状态的中继节点在随后时隙转为接收状态，后续再接收数据。In the forwarding stage, according to the "optimal" path selection algorithm, the "optimal" relay node is selected from all the relay nodes in the receiving state in the previous time slot to switch to the sending state, and the latest received "encoded" information

Forwarding to the next hop, the relay node in the sending state will switch to the receiving state in the subsequent time slot, and then receive data later.

The "optimal" path selection criterion h is specifically:

$\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; min</span>}<span\; class="notranslate">\; \{</span>{<span\; class="notranslate">\; |</span>{<span\; class="notranslate">\; \&PartialD;</span>}_{{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>{<span\; class="notranslate">\; |</span>{<span\; class="notranslate">\; \&PartialD;</span>}_{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="S"\; filenames="HDA0000030479640000031.png,HDA0000030479640000041.png"\; state="\{\{state\}\}">S</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>{<span\; class="notranslate">\; |</span>{<span\; class="notranslate">\; \&PartialD;</span>}_{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>{<span\; class="notranslate">\; |</span>{<span\; class="notranslate">\; \&PartialD;</span>}_{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>{<span\; class="notranslate">\; |</span>{<span\; class="notranslate">\; \&PartialD;</span>}_{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; \}</span>$

Wherein, n is the number of relay nodes, and the meanings of other letters are the same as above.

It should be noted that, due to the broadcast characteristics of the wireless channel, the nodes located in the communication range of the source nodes S1 and S2 and in the receiving state can receive the information sent by the source nodes S1 and S2. In contrast, the nodes in the sending state cannot Information received. Because nodes S1 and S2 do not need to know which relays need to send data, but only need to send directly.

Referring to FIG. 3 , it is a schematic diagram of performing PNC operation on the i-channel signal based on the embodiment shown in FIG. 2 .

The usual PNC mapping process is shown in Figure 3, considering the physical layer network coding mapping process involving i nodes, defining M to represent the digital symbol set, there are m _j ∈ M (j=1,...,i) and Subsequently, E is defined to represent a set of modulation symbols in the electromagnetic wave domain (PNC domain). Each m _j ∈ M (j=1,..., i) can be mapped to a corresponding modulation symbol e _j ∈ E (j=1,..., i), define f: M→E represents the modulation mapping function ,Right now

In the electromagnetic wave domain, multiple modulation symbols are superimposed in space, e ₁ +e ₂ +...+e _i =e′ _k ∈E′, where E′ is a set different from E and has a higher potential. Each superposition symbol e′ _k ∈ E′ received by the relay node must be mapped to a demodulation symbol m _k ∈ M according to a certain rule, and h is defined: E′→M represents the demodulation mapping function, that is, h(e′ _k ) = m _k . It is worth noting that f:M→E is a one-to-one mapping relationship, while h:E′→M is a many-to-one mapping relationship.

Referring to FIG. 4 , it is all possible system models based on the first two time slots of the embodiment shown in FIG. 2 .

Figure 4(a) is the system model of the first time slot. Due to the introduction of the idea of "optimal" path selection, starting from the second time slot, the relay node in the sending state is randomly determined according to the channel state, that is, the last time slot All relay nodes in the receiving state in the slot may switch to the sending state in this time slot. Figure 4(b)(c)(d) shows all possible system models for the second time slot. Obviously, starting from the second time slot, the number of all possible system models of this method depends on the number of relay nodes participating in forwarding, and the actual transmission process n chooses one.

Referring to FIG. 5 , it is a schematic diagram of implementation when there are 3 hops between the first and second groups of nodes that exist in space according to an embodiment of the present invention, and the number of relay nodes in each hop is 2.

For the 3-hop link, according to the difference of the data sent by the source node, two cases are exemplified. On the left side, the two source nodes send new data packets in each time slot; on the right side, the source nodes send new data packets and the network coded data of the received data packets in each time slot. Here are just examples of two cases, and there are other options for the data form sent by the source node.

Description of each time slot:

Time slot 1: source nodes S1 and S2 send data; relay group 1, that is, node R ₁₁ in Figure 5, and relay group 2, that is, node R ₃₁ in Figure 5, are in the receiving state, receiving data sent by source nodes S1 and S2 ;

Time slot 2: The operation of the source node is the same as that of time slot 1, but the specific data content sent is different; relay group 1 and relay group 2 select one of the relay nodes in this group as the sending node, and send time slot 1 The data received in the relay group is sent out; other relay nodes continue to be in the receiving state, receiving the data sent by the adjacent source node, the sending node in this relay group, and the sending node in the adjacent relay group.

Specifically, the source nodes S1 and S2 are still sending data, but the specific content of the data sent is different, and the relay node R ₁₁ in the relay group 1 and the relay node R ₃₁ in the relay group 2 act as the sender node, sends the data received in time slot 1, other relay nodes such as R ₁₃ and R ₃₃ are in the accepting state, for the relay node such as R ₁₃ , it receives the source node S1, the relay node R ₁₁ and the relay node The data sent by the relay node R ₃₁ ; for the relay node such as R ₃₃ , it receives the data sent by the source node S2, the relay node R ₃₁ and the relay node R ₁₁ .

Time slot 3: The operation of the source node is similar to that of time slot 2; for relay group 1 and relay group 2, the node in the sending state in the previous time slot changes to the receiving state, and selects from the nodes in the receiving state in the previous time slot One acts as a sending node, sending the data received in the previous time slot; starting from this time slot, the destination nodes at both ends of each time slot will receive a frame of new data corresponding to the source node.

Time slot 4: In this time slot, there are two pairs of nodes ((S1, D1), (S2, D2)), and the operation of nodes in the relay node group is similar to that of time slot 3. The only difference is the specific data content transmitted.

Time slot 5: In this time slot, there are two pairs of nodes ((S1, D1), (S2, D2)), and the operation of nodes in the relay node group is similar to that of time slot 4. The only difference is the specific data content transmitted.

Referring to FIG. 6 , it is a schematic diagram of implementation when the first and second groups of nodes that exist in space are 4 hops according to an embodiment of the present invention, and the number of relay nodes in each hop is 3.

For the 4-hop link, according to the difference of the data sent by the source node, two situations are exemplified. On the left side, the two source nodes send new data packets in each time slot; on the right side, the source nodes send new data packets and the network coded data of the received data packets in each time slot. Here are just examples of two of them, and there are other options for the data form sent by the source node.

Description of each time slot:

Time slot 1: Relay nodes in relay group 1 and relay group 3 are both in the receiving state, receiving data sent by adjacent source nodes;

Time slot 2: select a node in relay group 1 and relay group 3 as the sending node, and send the data received in the previous time slot, and other relay nodes in relay group 1 and relay group 3 as a receiving node. For example, relay node R 11 and relay node R ₃₃ are respectively selected as sending nodes in relay group ₁ and relay group 3, and relay node R ₁₂ and relay node R ₁₃ in relay group 1 continue to be receiving nodes , the relay node R ₃₂ and the relay node R ₃₁ in the relay group 3 continue to be the receiving nodes

At this time, all the nodes in the relay group 2 are in the receiving state, and receive the data sent by the sending nodes in the relay group 1 and the relay group 3 .

Time slot 3: Select one of the relay group 2 as the sending node to send the data received in the previous time slot, and the other nodes are in the receiving state. In relay group 1 and relay group 3: the node that was in the sending state in the last time slot changes to the receiving state, and receives the data sent by the sending node in this group, the adjacent source node and relay group 2; the node in the receiving state in the last time slot Choose one of them as the sending node.

For example, relay node R ₂₂ is selected as the sending node in relay group 2, and relay node R ₂₁ and relay node R ₂₃ in relay group 2 continue to be receiving nodes; The relay node R ₁₁ and the relay node R ₃₃ , which are the sending nodes in one time slot, are transferred to the receiving state, and the relay node R ₁₃ and the relay node R ₃₁ are selected as the sending nodes from the nodes in the receiving state in the previous time slot. , for the relay node R ₁₁ and the relay node R ₁₂ in the relay group 1 respectively receive the data sent by the source node S1, the relay node R ₁₃ and the relay node R ₂₂ in the relay group 2; for the relay group The relay node R ₃₂ and the relay node R ₃₃ in 3 receive the data sent by the source node S2, the relay node R ₃₁ and the relay node R ₂₂ in the relay group 2, respectively.

Time slot 4: Starting from this time slot, the destination nodes at both ends of each time slot will receive a frame of new data from the corresponding source node. The working mode of the nodes in each relay group is similar to that of the previous time slot.

Time slot 5: In this time slot, there are two pairs of nodes ((S1, D1), (S2, D2)), and the operation of nodes in the relay node group is similar to that of time slot 4. The only difference is the specific data content transmitted.

Referring to FIG. 7 , it is a schematic diagram of the realization of the first and second groups of nodes in space according to an embodiment of the present invention when there are 5 hops between them, and the number of relay nodes in each hop is 3. In this embodiment, only the case where the source node sends a new data packet in each time slot, it can be understood that the same applies to the case where the source node sends a new data packet in each time slot and the network coded data of the received data packet In this embodiment.

For the case of 5 links, it is similar to 4 links. Just starting from the fifth time slot, the destination nodes at both ends of each time slot will receive a frame of new data corresponding to the source node.

It can be seen that whether it is a 2-hop, 3-hop, 4-hop or 5-hop link, its working mode is basically the same. There are 2 main differences:

First, the number of preparation time slots for the destination nodes at both ends to receive new data from the corresponding source node is different;

Second, because the number of relay groups participating in the cooperation is different, the time slots for the relay groups at different locations to participate in the cooperation are also different. However, once participating, the basic mode is to select one of the nodes in the receiving state as the sending node according to certain rules, and send the data received in the previous time slot; the others are in the receiving state. In the next time slot, the node in the sending state enters the receiving state again, and one of the nodes in the receiving state in the previous time slot is selected as the sending node, and so on alternately.

To sum up, after determining the number of communication link hops, according to the description of the following point 4, properly consider the bidirectional data flow function of each node relay, and select the source node that can simplify the data combination complexity of the relay node as much as possible Send data type.

1. The two-way data flow converges at the relay node located at the "relative center" of the network, and continues to relay and forward after network coding; The relay node at the center, so the "relative center" is used to indicate the position where the two-way data intersection occurs.) Therefore, the data sent by the relay node in the sending state is the data after the two-way data flow is encoded by the network.

2. Starting from the second time slot, only one of the relay nodes participating in the cooperation (each hop) is always in the transmitting state, and the rest are in the receiving state. The relay node in the transmitting state is selected from all the relay nodes in the receiving state in the previous time slot according to the optimal path selection algorithm. There are also multiple actual transmission processes in each time slot, and the number of possible transmission models depends on each time slot. The number n of relay nodes that the group participates in forwarding;

3. The number of preparation time slots depends on the number of hops between the two end node pairs, that is, after the communication is initiated, after the number of time slots equal to the number of hops between the two end node pairs, each subsequent time slot Two-way interaction of a data packet corresponding to the source node can be realized;

通过适当调整系统传输链路上的信息内容，以最大限度抵消中继节点组内干扰以及组间反向传输的无用信息叠加；例如在2跳的情况下通过上述调整，是可以抵消中继节点组内干扰以及组间反向传输的无用信息叠加的；4. Since the data packets sent by nodes S1 and S2 in each time slot are bidirectionally transmitted in each subsequent hop forwarding, therefore, the interference information within the relay node group and the transmission information between groups will send data along with S1 and S2 The content and the number of transmission hops change. That is, after the number of hops between two end node pairs is determined, the content of the data packet sent by the source nodes at both ends can be adjusted. For example, after the second time slot in the case of 2 hops, source node i at any time The data sent by slot j can be adjusted as

By properly adjusting the information content on the system transmission link, the interference within the relay node group and the useless information superposition of the reverse transmission between groups can be offset to the greatest extent; for example, in the case of 2 hops, the above adjustment can offset the relay node Intra-group interference and superposition of useless information transmitted in reverse between groups;

5. The data packets sent by the nodes S1 and S2 in each time slot may be the new data packet and the network coded data of the received data packet on the basis of containing the new data packet.

The embodiment of the present invention comprehensively considers the cause of the low spectral efficiency of the two-way relay channel, and utilizes the cooperative transmission between relay nodes to maximize the spectral efficiency of the two-way relay channel, and with the increase in the number of relay forwarding hops, Its performance advantage is more and more obvious.

It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is a relationship between these entities or operations. There is no such actual relationship or order between them. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or device. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

Those of ordinary skill in the art can understand that all or part of the steps in the implementation of the above method can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, referred to herein as Storage media, such as: ROM/RAM, disk, CD, etc.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present invention are included in the protection scope of the present invention.

Claims (7)

1. An equivalent full-duplex realization method in a bidirectional relay network is characterized in that a first group of nodes (S1, D1) and a second group of nodes (S2, D2) with space existence are set, the nodes S1 and S2 are always in a sending state, the nodes D1 and D2 are always in a receiving state, no direct link exists between the nodes S1 and D2, and between the nodes S2 and D1, and information interaction is realized between the first group of nodes (S1, D1) and the second group of nodes (S2, D2) through at least one group of relay nodes; the method further comprises the following steps:

in the first time slot for transmitting data, the node S1 and the node S2 transmit data, and the nodes in the relay group are in a receiving state; the relay node in the receiving state completes physical layer network coding operation;

starting from the second time slot of the transmitted data, selecting one relay node from the relay nodes in the receiving state as a transmitting node in each time slot of the transmitted data, and enabling the rest nodes in the relay group to be in the receiving state; the relay node in the receiving state completes physical layer network coding operation;

starting from the number of the prepared time slots, only one relay node is in a transmitting state and the rest relay nodes are in a receiving state in each data transmission time slot and the relay nodes participating in assistance.

2. The method of claim 1, wherein the number of preparation slots is determined based on the number of hops separating the first set of nodes and the second set of nodes.

3. The method of claim 1, wherein the determining the number of preparation slots according to the number of hops between the first set of nodes and the second set of nodes comprises: the number of prepared time slots is equal to the number of hops between the first set of nodes and the second set of nodes after the communication is initiated.

4. The method of claim 1, wherein an optimal relay node is selected from all relay nodes in a receiving state in a previous time slot according to an optimal path selection algorithm to transit to a transmitting state.

5. The method of claim 4, wherein there are multiple actual transmission models per timeslot, and the specific number is the number of relay nodes participating in forwarding in each group.

6. The method of claim 1, wherein the node S1 and the node S2 each transmit a new data packet per slot; alternatively, network coded data is transmitted every time slot, the network coded data being the network coded data of the new data packet and the received data packet.

7. The method of claim 1, wherein the data transmitted by the relay node in the transmitting state is data encoded by a bidirectional data stream via a network.

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