Relay-resistant network optimization communication method based on geographic path length

Abstract

The invention provides a relay-resistant network optimization communication method based on geographic path length, and belongs to the field of wireless ad hoc networks. The method comprises the following steps: initializing a network; the source node initializes time slot counting and broadcasts an RTS data packet; the node decodes the RTS data packet, initializes time slot counting and forwards the RTS data packet downwards; after the destination node receives the first RTS data packet, the shortest path hop count between the source node and the destination node is determined, a physical distance threshold value is initialized, and a CTS data packet is sent; if the destination node does not receive the service data packet for a long time, the physical distance threshold value is corrected, and the CTS data packet is retransmitted; when receiving the CTS data packet, the node judges the identity of the node, and forwards the CTS data packet if the CTS data packet is a relay; and after the data transmission is completed, the state before the handshake process is recovered. According to the invention, the establishment mode of the controlled interception area is optimized, the forwarding of excessive nodes in the same hop in the controlled interception area is reduced, the average power consumption in communication is reduced, and the user capacity of the relay blocking network is improved.

Description

Technical Field

[0001] The invention relates to the field of wireless ad hoc networks, and in particular to a relay network optimization communication method based on geographical path length. Background Art

[0002] Maintaining effective connections and stable communications in harsh communication environments is an important research direction for mobile ad hoc networks, and has broad development prospects in scenarios such as post-disaster emergency communications. However, these scenarios have more demanding conditions than ordinary ad hoc network scenarios, such as demanding communication channels caused by complex environments, communication interference, topology changes caused by node mobility, and reliable delivery of key data with low latency. Although some current mobile ad hoc network solutions can solve some of these problems, these solutions have not made breakthroughs in some key challenges.

[0003] Relay networks can effectively solve the above-mentioned problems of mobile ad hoc networks. Relay networks are mobile ad hoc networks based on autonomous cooperative communication between nodes and TDMA time slot allocation technology. Nodes dynamically update their time slots through time slot allocation algorithms, coordinate the sending relationship between nodes, and avoid channel conflicts. Nodes can collaboratively send given messages to one or more nodes without much coordination. Under complex channel conditions, the collaboration between nodes can effectively improve the data transmission rate. In the relay network, a controlled interception area construction algorithm is used to build a collaborative path for each unicast stream, and multiple unicast streams are isolated to achieve the transmission of multiple unicast streams in the network. The controlled interception area construction algorithm can transmit data with lower latency and more reliable probability by constructing collaborative paths, but it also brings about the problem of too many collaborative nodes and a low number of unicast streams.

[0004] At present, the existing technologies are mainly concentrated in the following aspects: First: by optimizing the time slot scheduling in the relay network, a relay network with multiple source nodes can be realized at the same time, but the central scheduler control node needs to be introduced in the solution, and the actual application value is not high; Second: the controlled interception area construction algorithm in the relay network is expanded, the clustering algorithm is introduced, and a new relay network based on clustering is constructed. The construction efficiency of CBR (controlled interception area) is accelerated by clustering, which improves the network transmission efficiency to a certain extent, but the user capacity of the network has not increased, and the improvement is limited. Summary of the invention

[0005] In view of this, the present invention proposes a method for optimizing communication in a relay network based on geographic path length. Based on the geographic routing protocol, the method optimizes the establishment of a controlled interception area, increases the physical path length parameter, utilizes the sending and receiving of control messages between destination nodes, and jointly determines the identity of the intermediate node from the two dimensions of the number of path hops and the physical length of the path, thereby reducing excessive node forwarding of the same hop in the controlled interception area, reducing the average power consumption in communication, and reducing the size of the controlled interception area established for each unicast stream, thereby improving the user capacity of the relay network.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] A method for optimizing communication in a relay network based on geographic path length comprises the following steps:

[0008] S1, network initialization, all nodes complete time synchronization;

[0009] S2, source node v S Initialize the time slot count S = 0, after which the time slot count increases as the time slot increases; the source node v S Get your own time slot number T(v S ), the source node broadcasts an RTS data packet to the surrounding in its own time slot. The RTS data packet includes the number of hops between the current node and the source node, the physical length of the path between the current node and the source node, the coordinates of the source node, the coordinates of the current node, the time slot number of the current node, and the time slot count of the current node;

[0010] S3, node v j Received from node v i When receiving an RTS packet, decode the RTS packet and calculate the number of hops d(v S ,v j ), the physical length of the path between itself and the source node L route1 (v S ,v j ), its own time slot number, and record the coordinates of the source node (x s ,y s ), initialize its own time slot count count j =count i +1, count i For node v i The time slot count of node v j Forward the RTS packet downward in its own time slot; if a node receives the same RTS packet repeatedly, it will be discarded;

[0011] S4, destination node vD After receiving the first RTS packet, the shortest path hop count δ between the source node and the destination node is determined according to the receiving time, the threshold modification times N = 0 is initialized, and the physical distance threshold M is initialized. N The CTS packet includes the number of hops between the current node and the destination node, the physical length of the path between the current node and the destination node, the number of hops of the shortest path between the source node and the destination node, and the physical distance threshold M. N ;

[0012] S5, destination node v D After sending the CTS data packet, wait for receiving the service data packet. If the service data packet is not received within K time slots after the CTS data packet is sent, update N=N+1 and modify the physical distance threshold M. N , and resend the CTS packet;

[0013] S6, node v j Received from node v i When a CTS packet is received, the physical distance threshold M is obtained. N , the shortest path hop count δ between the source node and the destination node, calculate the hop count d(v D ,v j ), the physical length of the path between itself and the destination node L route2 (v D ,v j ), if d(v S ,v j )+d(v D ,v j )≤δ, then the node v j On the shortest path, it determines itself as a possible relay node, otherwise it determines itself as a blocking node and does not participate in relay forwarding; for a possible relay node, if it satisfies L route1 (v S ,v j )+L route2 (v D ,v j )≤M N , it determines itself as a relay node and sends CTS packets in its own time slot; otherwise, it determines itself as a blocking node and does not participate in relay forwarding;

[0014] S7. After the data transmission is completed, the source node initiates the cancellation of the controlled interception area, and each node cancels its own identity judgment and returns to the state before the handshake process.

[0015] Furthermore, the initial value M0 of the physical distance threshold is calculated as follows:

[0016]

[0017] Where D is the straight-line distance between the destination node and the source node, and θ is the angle between the line connecting the destination node and its previous node and the line connecting the source node and the destination node.

[0018] Furthermore, the physical distance threshold M N The correction method is:

[0019] M N =M N-1 ×1.3 N .

[0020] Furthermore, node v j The way to calculate your own time slot number is:

[0021] T(v j )=(T(v i )+1)%3

[0022] Among them, T(v j ) is the node v j The time slot number, T(v i ) is the time slot number of the previous node, and % means taking the remainder.

[0023] Furthermore, K=3δ.

[0024] The beneficial effects of the present invention are:

[0025] (1) It solves the problem that in the current relay network architecture, nodes coordinate the sending relationship through cooperative transmission but do not limit the number of nodes participating in the cooperative transmission. The present invention adopts the threshold setting based on the geographical path length to further accurately limit the number of nodes participating in the cooperative transmission, reduce the excessive node forwarding of the same hop in the controlled interception area, reduce the average power consumption in the communication, reduce the area size of each unicast flow, and thus improve the user capacity of the relay network.

[0026] (2) Improved content of RTS and CTS messages. The RTS and CTS messages of the present invention contain new necessary content. The path length L from the source node is added to RTS. route1 , the number of hops between the source node and the source node d(v S ,v j ), the source node coordinates parameters; CTS adds the shortest path hop count δ and physical threshold M between the source node and the destination node N And the path length L to the destination node route2 Based on these parameters, the present invention realizes the optimization of the relay network communication process.

[0027] (3) The problem of abnormal communication caused by poor initial threshold setting during the establishment of the controlled interception area is solved. When abnormal communication occurs, the destination node corrects the physical distance threshold, which can improve the robustness of the overall architecture.

[0028] In summary, the relay network in the prior art only limits the node identity by the shortest path hop number δ, which will lead to an excessive number of participating nodes, resulting in a decrease in the number of multicast links supported by the network. The present invention adds the parameter of geographic path length as a restriction, and N The dual parameters jointly participate in the node identity judgment, reducing the node redundancy in the controlled interception area. From the perspective of the entire network, the area of ​​the controlled interception area is reduced, and the number of controlled interception areas in the entire network increases, thereby increasing the network user capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a flow chart of a method for optimizing communication through a relay network according to an embodiment of the present invention;

[0030] Figure 2 is a schematic diagram of the approximate calculation principle of the physical distance threshold in an embodiment of the present invention;

[0031] Figure 3 It is an example diagram of network topology and node identity in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The present invention is further explained below in conjunction with the accompanying drawings and specific examples. This example is implemented on the premise of the technical solution of the present invention. It should be understood that this example is only used to illustrate the present invention and is not used to limit the scope of the present invention.

[0033] A method for optimizing communication in a relay network based on geographic path length, including time synchronization of all nodes in the network, broadcasting of RTS messages, calculation of intermediate parameters, broadcasting of CTS messages, and communication establishment and correction process, referring to Figure 1 , specifically including the following steps:

[0034] (1) Source node v S Initialize the time slot count S = 0, and increases with the time slot growth, assigning its own time slot number T(v S ), and broadcast RTS to the surroundings during the source node's sending time slot.

[0035] (2) Refer to the RTS message content shown in Table 1:

[0036] Table 1 RTS message content

[0037]

[0038] If the receiving node vj ∈V\{v s ,v D}Received from node v i The RTS packet is decoded and the hop distance d(v s ,v j )=d(v s ,v i )+1, add 1 to the hop distance, and calculate L route1 (v S ,v j )=L route1 (v S ,v i )+D(v i ,v j ) and store, record the coordinates of the source node (x s ,y s ), initialize its own time slot count count j =count i +1, according to the message in the data packet, the time slot number is allocated, and the specific time slot allocation is T(v j )=(T(v i )+1)%3. When the node reaches its own transmission time slot, i.e., T(v j )=count j %3, forward the RTS packet downward. If a node receives the same RTS packet repeatedly, it will be discarded.

[0039] (3) Receiving node v j The destination node v D When receiving the RTS data packet, it decodes and obtains the source node coordinates in the data packet, calculates and stores the physical distance D between the source and destination nodes in combination with its own node coordinates, and obtains the number of hops δ from the source node in the data packet. D =d(v s ,v D ) is the number of hops in the shortest path;

[0040] (4) Refer to the CTS message content shown in Table 2 Figure 2 The schematic diagram of the approximate calculation of the physical distance threshold is shown:

[0041] Table 2 CTS message content

[0042]

[0043] For the physical distance threshold M N Perform approximate calculation, initialize the physical distance threshold M0, and receive node v j Continue to send RTS packets in its own transmission time slot. jThe destination node v D When the CTS packet is sent in its own transmission time slot, the initialization threshold modification times N = 0, where in

[0044] (5) After the destination node completes sending the CTS data packet, it waits to receive the data packet. If it does not receive the data packet after waiting for more than K = 3δ time slots, the threshold modification times are increased by 1, and the physical distance threshold in the CTS data packet is modified by M. N =M N-1 ×1.3 N , resend the CTS packet;

[0045] (6) The receiving node first combines the received control message with the destination node hop distance d(v D ,v j ) and the hop distance d(v D ,v j ) determines whether the node is on the shortest path. If so, it is determined to be a possible relay node. Otherwise, it is determined to be a blocking node. Then all possible relay nodes are further combined with L in the control message. route2 (v D ,v j ) and the locally stored L route1 (v S ,v j ) and the physical distance threshold M in the control message N A comparison is made. If it is greater than the threshold, it is determined to be a blocking node. Otherwise, it is determined to be a relay node and participates in relay forwarding to complete the establishment of a controlled interception area.

[0046] (7) After completing the data transmission, the source node cancels the controlled interception area, cancels its own identity judgment, and returns to the state before the handshake process.

[0047] Combine the following Figure 3 The network topology and node identity example diagram are used to explain the effect achieved by this method:

[0048] First, for the path between the destination nodes, it can be seen that the shortest path length is 3 hops, and the nodes on the 4-hop path do not participate in relay forwarding. Secondly, for the destination node D, all its neighboring nodes should participate in cooperative transmission. However, with this method, after the dual restrictions of the shortest path hops and the geographical path length, only nodes C1 and C2 participate in cooperative transmission; for the C1 node, R1, R2, and R3 nodes are nodes that may participate in cooperative transmission, and for the C2 node, R3 and R4 are nodes that may participate in cooperative transmission. However, depending on the physical distance threshold limit, the above nodes only have the possibility of fully or partially participating in actual cooperative transmission, realizing the limitation of the number of nodes participating in cooperative transmission under the premise of ensuring the normal establishment of the link.

[0049] The present invention combines the shortest path with the physical distance threshold to restrict the nodes participating in the collaborative transmission. In the request communication stage, the message of the physical path length from the source node and the destination node is added to the RTS and CTS data packets. When passing each hop node, the parameter is calculated and updated; at the same time, the physical distance threshold parameter is set in the CTS data packet. While ensuring the shortest path, the number of previous hop nodes participating in the collaborative communication at the node is limited by the physical path length node by node. Under certain conditions, the threshold will also be modified to ensure the construction of the transmission path and the stable transmission of data.

[0050] In summary, the present invention optimizes the way of establishing a controlled interception area, reduces excessive node forwarding at the same hop in the controlled interception area, reduces the average power consumption in communication, and can effectively reduce the size of the controlled interception area for each unicast stream in the relay network, thereby further improving the user capacity of the relay network.

[0051] The above content is only used to illustrate the present invention and is not used to limit the scope of the present invention. After reading the present invention, various equivalents of the present invention will fall within the scope defined by the claims attached to this application for those skilled in the art.

Claims

1. A method for optimizing communication in a relay network based on geographic path length, characterized in that: The following steps are involved: S1, network initialization, all nodes complete time synchronization; S2, source node v S Initialize the time slot count S = 0, after which the time slot count increases as the time slot increases; the source node v S Get your own time slot number T(v S ), the source node broadcasts an RTS data packet to the surrounding in its own time slot. The RTS data packet includes the number of hops between the current node and the source node, the physical length of the path between the current node and the source node, the coordinates of the source node, the coordinates of the current node, the time slot number of the current node, and the time slot count of the current node; S3, node v j Received from node v i When receiving an RTS packet, decode the RTS packet and calculate the number of hops d(v S ,v j ), the physical length of the path between itself and the source node L route1 (v S ,v j ), its own time slot number, and record the coordinates of the source node (x s ,y s ), initialize its own time slot count count j =count i +1, count i For node v i The time slot count of node v j Forward the RTS packet downward in its own time slot; if a node receives the same RTS packet repeatedly, it will be discarded; S4, destination node v D After receiving the first RTS packet, the shortest path hop count δ between the source node and the destination node is determined according to the receiving time, the threshold modification times N = 0 is initialized, and the physical distance threshold M is initialized. N The CTS packet includes the number of hops between the current node and the destination node, the physical length of the path between the current node and the destination node, the number of hops of the shortest path between the source node and the destination node, and the physical distance threshold M. N ; S5, destination node v D After sending the CTS data packet, wait for receiving the service data packet. If the service data packet is not received within K time slots after the CTS data packet is sent, update N=N+1 and modify the physical distance threshold M. N , and resend the CTS packet; S6, node v j Received from node v i When a CTS packet is received, the physical distance threshold M is obtained. N , the shortest path hop count δ between the source node and the destination node, calculate the hop count d(v D ,v j ), the physical length of the path between itself and the destination node L route2 (v D ,v j ), if d(v S ,v j )+d(v D ,v j )≤δ, then the node v j On the shortest path, it determines itself as a possible relay node, otherwise it determines itself as a blocking node and does not participate in relay forwarding; for a possible relay node, if it satisfies L route1 (v S ,v j )+L route2 (v D ,v j )≤M N , it determines itself as a relay node and sends CTS packets in its own time slot; otherwise, it determines itself as a blocking node and does not participate in relay forwarding; S7. After the data transmission is completed, the source node initiates the cancellation of the controlled interception area, and each node cancels its own identity judgment and returns to the state before the handshake process.

2. The method for optimizing communication through a relay network based on geographic path length according to claim 1, characterized in that: The initial value M0 of the physical distance threshold is calculated as follows: Where D is the straight-line distance between the destination node and the source node, and θ is the angle between the line connecting the destination node and its previous node and the line connecting the source node and the destination node.

3. The method for optimizing communication through a relay network based on geographic path length according to claim 1, characterized in that: Physical distance threshold M N The correction method is: M N =M N-1 ×1.3 N 。 4. The method for optimizing communication through a relay network based on geographic path length according to claim 1, characterized in that: Node v j The way to calculate your own time slot number is: T(v j )=(T(v i )+1)%3 Among them, T(v j ) is the node v j The time slot number, T(v i ) is the time slot number of the previous node, and % means taking the remainder.

5. The method for optimizing communication through a relay network based on geographic path length according to claim 1, characterized in that: K = 3δ.

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