Multi-node resistance relay network unicast flow transmission method based on position information

Abstract

The invention provides a multi-node relay-resistant network unicast flow transmission method based on position information, and belongs to the field of wireless ad hoc networks. According to the method, a broadcasting scheme is divided into an initialization stage, a message control stage and a data transmission stage; in the message control stage, time slot allocation of nodes and establishment of a controlled interception area are completed at the same time by utilizing an RTS-CTS interaction mechanism, and the success rate of network establishment is further improved by introducing an ARQ mechanism; in the data transmission stage, the advantages of the resistance relay network during data transmission are utilized, and a TDMA time slot allocation algorithm is combined, so that a large amount of data is transmitted, and the network load and the transmission success rate are improved while the energy overhead is effectively reduced. According to the method, the problem of network dynamic topology change caused by node movement in the ad hoc network is solved, and the problem of excessive data packet forwarding overhead in a high-density node scene is solved. Through the unicast flow transmission scheme, unicast transmission with low control overhead, high load and high delivery rate in a high-density network can be realized.

Description

Technical Field

[0001] The invention belongs to the field of mobile ad hoc networks, and mainly relates to a multi-node relay network unicast stream transmission method. Background Art

[0002] Mobile ad hoc networks (MANETs) are wireless, multi-hop, self-organizing mobile communication networks that do not rely on fixed infrastructure and can be quickly established at any time and any place. Each node in the network is relatively independent and has the functions of data reception and data transmission; the nodes can move freely, and the network topology changes dynamically; the high degree of collaboration between nodes and the distributed and parallel operation of nodes make the network highly robust and fault-tolerant. Mobile ad hoc networks have many advantages. They were originally used in the military field, and later they were widely used in field communications, rescue and emergency response, wireless sensor networks and other environments that are separated from the backbone network.

[0003] Barrage Relay Networks (BRN) are a new type of self-organizing network technology. The core features are low latency, low overhead and high reliability. Barrage Relay Networks (BRN) are a mobile self-organizing network with timely response, strong robustness and high robustness. They use a solution that combines time division multiple access (TDMA) technology with autonomous cooperative communication technology. At the same time, they have good scalability and have great potential in improving protocol models and optimizing network performance. BRN effectively combines a series of modern waveform processing technologies for cooperative communication, such as space-time coding, distributed beamforming, frequency hopping and modern error correction coding. On the basis of barrage relay networks, the concept of controlled-barrage regions (CBR) is proposed to promote barrage relay networks to specific applications. In barrage relay networks, a cooperative path is constructed for each unicast stream through a controlled-barrage region construction algorithm, and multiple unicast streams are isolated to achieve the transmission of multiple unicast streams in the network. Compared with mobile ad hoc network protocols, relay networks do not store the topology information and its changes of the entire network, which greatly reduces the network delay and overhead and has good scalability and robustness.

[0004] The relay network uses the blocking function of some nodes to establish a controlled interception area. The controlled interception area is a closed message area. The forwarding of any information in the area will not cross the boundary of the area, ensuring the reliability of the message. The nodes in the controlled interception area are divided into four types: source nodes, destination nodes, relay nodes, and blocking nodes. Nodes outside the controlled interception area are called irrelevant nodes because they do not participate in the message transmission process. When the source node sends information to the target node, it will first send and receive control messages. The intermediate node determines its position in the network by receiving the control messages from the source node and the target node, and then determines its role in this communication task (relay node or blocking node), and finally establishes a controlled interception area. After all nodes in the controlled interception area confirm their identities, the processing method for subsequent received messages has been determined, so the received messages can be directly processed at the corresponding behavioral level (forwarded or discarded) without being submitted to the upper layer, which effectively improves the communication speed within the controlled interception area. Summary of the invention

[0005] The present invention is mainly intended to solve the problem that in the existing relay network solution, a large number of relay nodes and redundant transmission will be generated under high node density, resulting in high network power consumption; the present invention provides a multi-node relay network unicast flow solution based on location information.

[0006] The technical solution of the present invention is a multi-node relay network unicast stream transmission method based on location information, which includes the following cyclic steps:

[0007] Step A: Initialization phase;

[0008] Step B: Control message stage;

[0009] Step C: Data transmission stage;

[0010] The specific method of step A is:

[0011] Step A1: Initialize nodes in the network and achieve clock synchronization;

[0012] Step A2: The application layer of the source node with unicast stream transmission requirements initiates a unicast stream transmission request, sets default parameters such as network lifecycle TTL and message retransmission period TTR, and encapsulates and prepares a broadcast control message;

[0013] Step A3: Entering the control message phase, the time slot count starts counting from 0;

[0014] The specific method of step B is:

[0015] If the node is a source node, define its own time slot T as 0; send a request to send message RTS containing time slot T, the RTS message contains: message type, unicast stream source-destination information, source node location information, and the number of hops from the source node Hop2S; if the node is a common node, wait for time slot allocation;

[0016] Step B1: The N-slot STDMA protocol is used in the control message stage and the data transmission stage. If a common node receives an RTS message for the first time, it allocates its own time slot T according to the Hop2S in the received control message. The specific scheme is as follows:

[0017] T=(Hop2S+1)%N

[0018] Where % is the remainder algorithm, after which the Hop2S field is updated and the RTS message is forwarded. The specific operation is to add 1 to the corresponding field value; otherwise, the RTS message is discarded and not forwarded;

[0019] Step B2: If the node that receives the request to send message for the first time is the target node of the unicast stream transmission, then in addition to the above actions, it is necessary to encapsulate a reply confirmation message CTS, which contains: message type, unicast stream source-destination information, destination node location information, the number of hops from this node to the destination node Hop2D, source-destination node hop distance information MaxHop, and geographic location restriction parameters;

[0020] Step B3: If the node receiving the confirmation message for the first time is a common node, the node determines its identity in the current unicast stream transmission according to the hop count information in the received control message; the hop count determination formula is:

[0021] Hop2S+Hop2D=MaxHop

[0022] In addition to satisfying the above hop count judgment formula, the position of an ordinary node should be within the theoretical optimal boundary to be judged as a relay node. In unicast stream transmission, it undertakes the forwarding task, updates the Hop2D field in the CTS message, and the specific operation is to add 1 to the corresponding field value and forward the CTS message; otherwise, it is judged as a blocking node and discards the CTS message.

[0023] Step B4: If the source node receives the CTS message, it indicates that the controlled interception area is constructed, the unicast stream is transmitted, and the data transmission phase is entered; if the destination node times out and does not receive a data packet as a reply confirmation, the message parameters are adjusted, and the specific operation is to add Δ to the Elli2a field value and retransmit the CTS message; Elli2a is a field in the control message indicating the major axis length of the ellipse boundary, and Δ indicates the additional width of the adaptive adjustment;

[0024] The data transmission phase:

[0025] Step C1: If the node is a source node, it is ready to send a data packet, and when the time slot count satisfies count%N=T, it sends a data packet broadcast;

[0026] Step C2: If the node is a relay node and it is the first time to receive this data packet, when the time slot count satisfies count%N=T, the data packet is forwarded. If a duplicate data packet is received, it is discarded.

[0027] Step C3: If the node is a blocking node, the node directly discards the data packet after receiving it without any forwarding;

[0028] Step C4: If the time slot count count is less than the network life cycle TTL, repeat steps C1, C2, and C3; if the time slot count count is greater than or equal to the network life cycle TTL, proceed to step C5;

[0029] Step C5: All node types are changed to common nodes, the time slot count is reset to zero, and the initialization phase is entered.

[0030] Furthermore, the theoretical optimal boundary in step B3 is expressed as: D S-X +D X-D ≤2a,

[0031] 2a is the major axis length of the ellipse area, which is determined by the Elli2a field in the control message. The initial value of this field is: The operation is rounded up, d0 represents the transmission radius of the node, D S-X Indicates the geographical distance between the node receiving the control message and the source node, D X-D Indicates the geographical distance between the node receiving the control message and the destination node, D S→D Represents the geographical distance between the destination node and the source node; the value of 2a is determined by the following formula: 2a=Elli2a×d0, so that all ordinary nodes located at the boundary of the controlled interception area when the node distribution is optimal will be determined as relay nodes.

[0032] Furthermore, in step B3, the position of the ordinary node should be within the theoretical optimal boundary to be determined as a relay node and the following conditions must be met:

[0033] d S-X +d X-D =d S-D

[0034] Among them, d S-D Corresponding to the MaxHop field in the CTS message, it indicates the number of hops from the source node to the destination node; d S-X Corresponding to the Hop2S field in the RTS message, it indicates the hop distance information of a node X from the source node; d X-DThe Hop2D field in the CTS message indicates the hop distance between a node X and the destination node. This decision formula ensures that all relay nodes are on the shortest path from the source to the destination node.

[0035] Furthermore, in step B3, the position of the ordinary node should be within the theoretical optimal boundary to be determined as a relay node and the following conditions must be met:

[0036] D S-X +D X-D ≤2a

[0037] Among them, D S-X , D X-D Indicates the coordinate distance information of a node X from the source node and the destination node. Node X obtains the coordinates of the source node and the destination node through the SrcXPos, SrcYPos, DstXPos, and DstYPos fields in the RTS message and the CTS message, and then calculates and knows; 2a is the major axis length of the geometric modeling ellipse in this scheme, which is calculated through the Elli2a field in the CTS message.

[0038] The above-mentioned phase A algorithm is as follows Figure 2 As shown, the algorithm flow chart of stage B and C is as follows Figure 3 As shown:

[0039] As described above, the present invention designs a unicast streaming transmission scheme based on geographic location information, which has the following advantages compared to the traditional relay broadcast scheme:

[0040] 1. The present invention realizes spatial multiplexing based on the traditional TDMA protocol, improves the time slot utilization rate, enables nodes to fully utilize channel resources for data transmission, does not cause competition for channel resources between nodes, and improves network transmission efficiency.

[0041] 2. The control message stage in the present invention can quickly and effectively complete the time slot allocation process and effectively overcome the impact of node density on network broadcasting.

[0042] 3. The unicast stream transmission scheme in the present invention reduces the number of nodes involved in relay forwarding, effectively reducing network power consumption while ensuring the success rate of data packet transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a schematic diagram of the RTS message.

[0044] Figure 2 This is a schematic diagram of the CTS message.

[0045] Figure 3 Schematic diagram of the theoretical boundary of the controlled interception area.

[0046] Figure 4 This is the flow chart of the control message stage.

[0047] Figure 5 This is the flow chart of the data transmission phase.

[0048] Figure 6 Schematic diagram of time slot allocation. DETAILED DESCRIPTION

[0049] Before introducing the technical solution of the present invention in detail, the following description is given:

[0050] 1. N-slot STDMA protocol is used in the control message stage and data transmission stage;

[0051] 2. The nodes in the mobile ad hoc network are synchronized by default.

[0052] 3. The slot count parameter count is automatically increased by one every time slot and is cleared after a network life cycle is completed.

[0053] In order to make the objectives, technical methods and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the implementation modes and the accompanying drawings.

[0054] like Figure 6 As shown, there are 21 nodes in the self-organizing network, unicast stream is transmitted, and the parameters N=3 and Δ=1.

[0055] Initialization phase:

[0056] (A1) Initialization of nodes in the network to achieve clock synchronization;

[0057] (A2) The application layer of the source node with unicast stream transmission demand initiates a unicast stream transmission request, sets the default parameters of network life cycle TTL and message retransmission period TTR, and encapsulates and prepares a broadcast control message;

[0058] (A3) Entering the control message phase, the time slot count starts counting from 0;

[0059] The control message stage:

[0060] If the node is a source node, it defines its own time slot T as 0; it sends a request to send message (RTS) containing time slot T. The RTS message contains: message type, unicast stream source-destination information, source node location information, and the number of hops from the source node Hop2S; ordinary nodes wait for time slot allocation;

[0061] The 3-slot STDMA protocol is used in the control message stage and the data transmission stage. If a common node receives an RTS message for the first time, it allocates its own time slot T according to the time slot information in the received control message. The specific scheme is as follows:

[0062] T=(Hop2S+1)%3

[0063] Wherein Hop2S is the corresponding field in the RTS message, % is the modulo algorithm, and then the field is updated, and the specific operation is to add 1 to the corresponding field value; otherwise, the RTS message is discarded and not forwarded;

[0064] (B1) If the node that first receives the request to send message is the target node of the unicast stream transmission, then in addition to the above actions, it needs to encapsulate a reply confirmation to send message (CTS), and the CTS message includes: message type, unicast stream source-destination information, destination node location information, the number of hops from this node to the destination node Hop2D, source-destination node hop distance information, and geographic location restriction parameters;

[0065] (B2) If the first received confirmation message is a common node, then the node determines its identity in this unicast stream transmission based on the hop count information in the received control message; the hop count determination formula is: op2S+Hop2D=MaxHop. In addition to satisfying the above hop count determination formula, the position of the common node should also be within the theoretical optimal boundary to be determined as a relay node, and to undertake the forwarding task in the unicast stream transmission, update the Hop2D field in the CTS message, and the specific operation is to add 1 to the corresponding field value and forward the CTS message; otherwise, it is determined to be a blocking node and the CTS message is discarded;

[0066] The content of the above RTS message is as follows Figure 1 As shown, the content of the CTS message is as follows Figure 2 As shown:

[0067] In the present invention, the theoretical optimal boundary of the relay node is determined by the following method:

[0068] Assume that in an ideal situation, the node density in the network is infinite. When the distance between two nodes is within the communication range of each other, they can communicate with each other. The upper limit of this communication distance is called the single-hop transmission radius d0. As the data packet propagates hop by hop, a series of concentric circles will be formed, and each circle represents the distance of one hop. When considering the distance (D_(SD)) between the source node (S) and the destination node (D), the boundary of the CBR can be regarded as an ellipse formed by the intersection of these concentric circles and the concentric circles emitted from the destination node. The closed area formed by the intersection of the ellipse and the two concentric circle families formed by the source node and the destination node forms the boundary of the relay node distribution. The Elli2a field value determines the major axis of the ellipse. All relay nodes that meet the specific distance sum condition are located inside the same ellipse. This ellipse actually becomes the boundary of the controlled interception area when the node distribution is optimal. The regional schematic diagram is shown as follows Figure 3 shown.

[0069] The theoretical optimal boundary of relay nodes is determined by the following method:

[0070] D represents the geographical distance between nodes, d0 represents the transmission radius of the node, and the distance between the node (S) and the destination node (D), i.e. the focal length of the ellipse, is recorded as D S-D . According to the geometric relationship, the nodes inside the ellipse satisfy: D S-X +D X-D ≤2a, 2a is the major axis length of the ellipse area, which is determined by the Elli2a field in the control message. The initial value of this field is: The operation is rounded up. The value of 2a is determined by the following formula: 2a = Elli2a × d0, so that all ordinary nodes located at the boundary of the controlled interception area when the node distribution is optimal will be determined as relay nodes.

[0071] (B3) If the source node receives the CTS message, it indicates that the controlled interception area is constructed, the unicast stream can be transmitted, and the data transmission phase begins; if the destination node does not receive the data packet, the message parameters are adjusted and the CTS message is retransmitted. The specific operation is to increase the Elli2a field value by 1 in each retransmission;

[0072] After the control message stage is completed, Figure 6 As shown, the nodes in the network have been assigned their own time slot information, the identity of each node is clear, and the unicast stream can start to be transmitted in the network.

[0073] C. Data transmission stage

[0074] (C1) If the node is a source node, it prepares to send a data packet, and sends a data packet broadcast when the time slot count satisfies count%N=T;

[0075] (C2) If the node is a relay node and receives the data packet for the first time, it forwards the data packet when the time slot count satisfies count%N=T. If a duplicate data packet is received, it is discarded.

[0076] (C3) If the node is a blocking node, the node will directly discard the data packet after receiving it without any forwarding;

[0077] (C4) If the time slot count count is less than the network life cycle TTL, repeat steps C1, C2, and C3; if the time slot count count is greater than or equal to the network life cycle TTL, proceed to step C5;

[0078] (C5) All node types are changed to ordinary nodes, the time slot count is reset to zero, and the initialization phase is entered.

[0079] The present invention is characterized in that:

[0080] 1. Based on TDMA technology, a cooperative communication algorithm for spatial multiplexing of time slots is implemented, so that nodes can make full use of channel resources to send data without causing competition for channel resources between nodes, thereby improving network transmission efficiency.

[0081] 2. The control message stage is combined with the automatic retransmission mechanism, which can quickly and effectively complete the time slot allocation through the request-confirmation interaction process, and effectively overcome the impact of high node density on network broadcasting.

[0082] 3. The unicast stream transmission solution can make full use of the spatial gain brought by cooperative communication, and effectively reduce network power consumption while ensuring the success rate of data packet transmission at a certain level.

[0083] 4. The unicast stream transmission scheme of the present invention solves the problem of dynamic network topology changes caused by node movement in an ad hoc network by periodizing the three phases.

Claims

1. A method for transmitting unicast streams in a multi-node relay network based on location information, the method comprising the following loop steps: Step A: Initialization phase; Step B: Control message stage; Step C: Data transmission stage; The specific method of step A is: Step A1: Initialize nodes in the network and achieve clock synchronization; Step A2: The application layer of the source node with unicast stream transmission requirements initiates a unicast stream transmission request, sets default parameters such as network lifecycle TTL and message retransmission period TTR, and encapsulates and prepares a broadcast control message; Step A3: Entering the control message phase, the time slot count starts counting from 0; The specific method of step B is: If the node is a source node, define its own time slot T as 0; send a request to send message RTS containing time slot T, the RTS message contains: message type, unicast stream source-destination information, source node location information, and the number of hops from the source node Hop2S; if the node is a common node, wait for time slot allocation; Step B1: The N-slot STDMA protocol is used in the control message stage and the data transmission stage. If a common node receives an RTS message for the first time, it allocates its own time slot T according to the Hop2S in the received control message. The specific scheme is as follows: T=(Hop2S+1)%N Where % is the remainder algorithm, after which the Hop2S field is updated and the RTS message is forwarded. The specific operation is to add 1 to the corresponding field value; otherwise, the RTS message is discarded and not forwarded; Step B2: If the node that receives the request to send message for the first time is the target node of the unicast stream transmission, then in addition to the above actions, it is necessary to encapsulate a reply confirmation message CTS, which contains: message type, unicast stream source-destination information, destination node location information, the number of hops from this node to the destination node Hop2D, source-destination node hop distance information MaxHop, and geographic location restriction parameters; Step B3: If the node receiving the confirmation message for the first time is a common node, then determine its identity in this unicast stream transmission according to the hop count information in the received control message; The hop count decision formula is: Hop2S+Hop2D=MaxHop In addition to satisfying the above hop count judgment formula, the position of an ordinary node should be within the theoretical optimal boundary to be judged as a relay node. In unicast stream transmission, it undertakes the forwarding task, updates the Hop2D field in the CTS message, and the specific operation is to add 1 to the corresponding field value and forward the CTS message; otherwise, it is judged as a blocking node and discards the CTS message. Step B4: If the source node receives the CTS message, it indicates that the controlled interception area is constructed, the unicast stream is transmitted, and the data transmission phase is entered; if the destination node times out and does not receive a data packet as a reply confirmation, the message parameters are adjusted, and the specific operation is to add Δ to the Elli2a field value and retransmit the CTS message; Elli2a is a field in the control message indicating the major axis length of the ellipse boundary, and Δ indicates the additional width of the adaptive adjustment; The data transmission phase: Step C1: If the node is a source node, it is ready to send a data packet, and when the time slot count satisfies count%N=T, it sends a data packet broadcast; Step C2: If the node is a relay node and it is the first time to receive this data packet, when the time slot count satisfies count%N=T, the data packet is forwarded. If a duplicate data packet is received, it is discarded. Step C3: If the node is a blocking node, the node directly discards the data packet after receiving it without any forwarding; Step C4: If the time slot count count is less than the network life cycle TTL, repeat steps C1, C2, and C3; if the time slot count count is greater than or equal to the network life cycle TTL, proceed to step C5; Step C5: All node types are changed to common nodes, the time slot count is reset to zero, and the initialization phase is entered.

2. A method for transmitting unicast streams in a multi-node relay network based on location information as claimed in claim 1, characterized in that: The theoretical optimal boundary in step B3 is expressed as: D S-X +D X-D ≤2a, 2a is the major axis length of the ellipse area, which is determined by the Elli2a field in the control message. The initial value of this field is: The operation is rounded up, d0 represents the transmission radius of the node, D S-X Indicates the geographical distance between the node receiving the control message and the source node, D X-D Indicates the geographical distance between the node receiving the control message and the destination node, D S→D Represents the geographical distance between the destination node and the source node; the value of 2a is determined by the following formula: 2a=Elli2a×d0, so that all ordinary nodes located at the boundary of the controlled interception area when the node distribution is optimal will be determined as relay nodes.

3. A method for transmitting unicast streams in a multi-node relay network based on location information as claimed in claim 1, characterized in that: In step B3, the position of the ordinary node should be within the theoretical optimal boundary to be determined as a relay node. The following conditions must also be met: d S-X +d X-D =d S-D Among them, d S-D Corresponding to the MaxHop field in the CTS message, it indicates the number of hops from the source node to the destination node; d S-X Corresponding to the Hop2S field in the RTS message, it indicates the hop distance information of a node X from the source node; d X-D The Hop2D field in the CTS message indicates the hop distance between a node X and the destination node. This decision formula ensures that all relay nodes are on the shortest path from the source to the destination node.

4. A method for transmitting unicast streams in a multi-node relay network based on location information as claimed in claim 1, characterized in that: In step B3, the position of the ordinary node should be within the theoretical optimal boundary to be determined as a relay node. The following conditions must also be met: D S-X +D X-D ≤2a Among them, D S-X , D X-D Indicates the coordinate distance information of a node X from the source node and the destination node. Node X obtains the coordinates of the source node and the destination node through the SrcXPos, SrcYPos, DstXPos, and DstYPos fields in the RTS message and the CTS message, and then calculates and knows; 2a is the major axis length of the geometric modeling ellipse in this scheme, which is calculated through the Elli2a field in the CTS message.

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