Improved AODV routing method for marine cross-media acoustic and electrical cooperative networks

Abstract

The present invention belongs to the field of marine cross-medium acoustic and electrical cooperative network communication technology, and discloses an improved AODV routing method for a marine cross-medium acoustic and electrical cooperative network. The method introduces a link stability factor of radio and underwater acoustic transmission when establishing a route; the surface cross-medium node specifies relevant equipment for data transmission according to the type of the destination node; after the node receives a routing response and establishes a route, it sets a timer to send a HELLO packet for route maintenance, and other nodes that have not established a route do not send a HELLO packet; after the underwater destination node receives a routing request, it sends two consecutive routing responses to the source node. The present invention improves the route establishment and maintenance mechanism, introduces an acoustic and electrical weighted hop count and a link stability factor, solves the problems of excessive traditional AODV notification packets leading to underwater transmission packet collision, and the principle of minimum hop count leading to low packet delivery rate and large delay, reduces network delay, and improves the packet delivery rate and throughput of the integrated network.

Description

Technical Field

[0001] The present invention belongs to the technical field of marine cross-media acoustic and electric cooperative network communication, relates to a communication ad hoc network routing protocol, and particularly relates to a routing protocol for a cross-media acoustic and electric cooperative communication network, and especially relates to an improved AODV routing method for a marine cross-media acoustic and electric cooperative network. Background Art

[0002] The ocean cross-medium acoustic-electric collaborative network integrates underwater acoustic and radio communication methods. Nodes such as unmanned underwater vehicles (AUVs) and sensors below the sea surface use underwater acoustic communication, while nodes such as buoys and ships on the sea surface integrate both underwater acoustic and radio communication methods to achieve cross-medium communication. Equipment such as drones above the sea surface uses radio for communication. The network uses self-organizing network protocols to organize underwater, surface, and aerial nodes into an interconnected three-dimensional information network, providing an effective technical means for real-time sharing of ocean information.

[0003] In an acoustic-electric collaborative network, information is transmitted above the ocean surface via radio, while information is transmitted below the surface via underwater acoustics. These two transmission methods differ significantly in terms of transmission rate and latency. There are two main approaches for acoustic-electric collaborative routing protocols: separate networking of different media and integrated acoustic-electric collaborative networking. Regarding separate networking of different media, Yang Yuxuan proposed a hop-count-based underwater acoustic routing protocol, MAVOR. This protocol uses multiple buoy nodes and replaces the distance from the underwater node to the surface with the number of hops from the underwater node to the surface node. This ensures that data packets generated by the underwater node reach the surface buoy node in the direction with the minimum number of hops. During the surface forwarding phase, a radio opportunistic routing protocol is used. This routing protocol only enables one-way information transmission. Ding Jiannan et al. proposed a cross-medium adaptive routing strategy, using the AODV routing protocol on the surface using terrestrial radio and the HH-VBF routing protocol underwater to achieve acoustic-electric collaborative transmission. Before transmission, the source node calculates the transmission delay of different links to determine whether to use the surface link or the underwater link. However, this method requires obtaining the location information of the destination node before the source node sends data. Liu Yangfei proposed research on opportunistic routing algorithms for ocean acoustic-electric collaborative networks. For underwater routing, he designed a forwarding selection method based on depth weighting and node residual energy. To address the data forwarding mechanism for surface buoy nodes, he proposed a location-based priority sorting method. However, this routing method only enables one-way information transmission.

[0004] Regarding integrated network routing, Tan Yanjie proposed flooding routing for acoustic-electrical collaboration and radio-priority forwarding routing. He detailed the principles of the radio-priority forwarding routing protocol and improved the RREQ and RREP frame formats, adding node load and remaining energy as a basis for node forwarding decisions. Jiang Zilong conducted simulation analysis of the performance of AODV and OLSR in acoustic-electrical collaborative networks. However, these routing methods have high overhead and are prone to channel conflicts during underwater acoustic transmission.

[0005] Currently, most routing strategies that network different media separately only enable one-way transmission from underwater to surface, or require the source node to obtain the destination node's location information before sending data, making practical application difficult. Most integrated routing strategies currently directly apply traditional radio ad hoc routing algorithms to acoustic-electric collaborative networks, resulting in high overhead and poor adaptability to underwater environments.

[0006] Through the above analysis, the problems and defects of the existing technology are as follows:

[0007] (1) Currently, most routing strategies that use different media to form networks can only achieve one-way transmission from underwater to surface, or the source node needs to obtain the location information of the destination node before sending data, which makes practical application difficult.

[0008] (2) Most of the existing integrated networking routing currently directly applies the traditional radio self-organizing network routing algorithm to the acoustic-electric cooperative network, which has problems such as high overhead and poor adaptability to underwater environments. Summary of the Invention

[0009] To overcome the problems existing in the related art, the embodiments disclosed in the present invention provide an improved AODV routing method for an ocean cross-medium acoustic-electric cooperative network. The technical solution is as follows:

[0010] The present invention is implemented as follows: an improved AODV routing method for an ocean cross-medium acoustic-electric collaborative network includes route search, route reply, and route maintenance;

[0011] When establishing a route, the link stability factor of radio and underwater acoustic transmission is introduced. After the route is established, each node determines whether the route is invalid by whether it can receive the HELLO packets broadcast regularly by its neighbors.

[0012] The surface cross-medium node specifies a device for data transmission based on the type of the destination node. When the cross-medium node's underwater acoustic device receives a routing request, if the destination node is an airborne node, it directly forwards the request through the buoy's radio device. If the destination node is an underwater node, if the surface cross-medium node receives a routing request from the underwater node, it forwards the routing request through the radio device. If the surface cross-medium node's radio device receives a routing request, it forwards the routing request simultaneously through the underwater acoustic device and the radio device.

[0013] After the node receives the routing response and establishes the route, it sets a timer to send HELLO packets for route maintenance. Nodes that have not established routes do not send HELLO packets.

[0014] After receiving the routing request, the underwater destination node sends two routing responses to the source node in succession.

[0015] Further, route search includes:

[0016] (1) When the source node has data to send to the destination node, the source node checks whether there is a route to the destination node. If so, the data is sent directly; if not, the source node sends a route request RREQ to start establishing the route;

[0017] (2) When a node receives a routing request, it determines whether the TTL of the routing request is a finite value. If not, it is discarded. If it is a finite value, it calculates the distance between the node and the previous hop node and the single-hop link stability factor RQ value. The RQ value is added to the total support value ALLRQ in RREQ and divided by the number of hops to obtain the average link quality AVGRQ.

[0018] (3) The node determines whether it has received an RREQ with the same ID. If not, it directly stores or updates the path to the source node in the routing table. If it has received an RREQ with the same ID, it determines whether AVGRQ is greater than the value in the existing routing table. If so, it stores or updates the path to the source node in the routing table. If AVGRQ is not greater than the value in the existing routing table, it discards the routing request.

[0019] (4) Determine whether it is the destination node or there is a path to the destination node. If so, send two routing response RREPs to the source node. When the source node receives the RREPs, the route establishment is complete.

[0020] (5) If the node is not the destination node or there is a path to the destination node, determine whether the node is a buoy node;

[0021] (6) If the node is a buoy node, determine whether the node receives a RREQ from an underwater acoustic device. If so, subtract b from the routing request survival hop count TTL, and the node continues to broadcast the RREQ using radio, and the next-hop node continues to execute step (2); if the node does not receive a RREQ from an underwater acoustic device, determine whether the destination node is an underwater node. If not, subtract b from the node routing request survival hop count TTL, broadcast the RREQ using radio, and the next-hop node continues to execute step (2); if the destination node is an underwater node, subtract b from the node routing request survival hop count TTL, continue to broadcast the RREQ using radio, and at the same time subtract a from the node request survival hop count TTL, and continue to broadcast the RREQ using underwater acoustic, and the next-hop node continues to execute step (2); a is the one-hop weight coefficient of the underwater acoustic sensor node, and b is the one-hop weight coefficient of the radio node;

[0022] (7) If the node is not a buoy node, determine whether the node is an underwater acoustic node. If so, subtract a from the node request survival hop count TTL, and continue to broadcast the RREQ using underwater acoustic, and the next-hop node continues to execute step (2); if the node is not an underwater acoustic node, subtract b from the node routing request survival hop count TTL, broadcast the RREQ using radio, and the next-hop node continues to execute step (2).

[0023] In step (1), the source node checks whether there is a route to the destination node, including: the routing request data packet contains the survival hop count TTL. If the routing reply has not been received for a long time, increase the survival hop count and continue to send the routing request.

[0024] In step (2), the number of hops passed by the routing request is the weighted hop count Hop, and the expression is:

[0025] Hop = a * Hop uw + b * Hop wr

[0026] In the formula, a is the one-hop weight coefficient of the underwater acoustic sensor node, Hop uw is the number of hops of the underwater acoustic node passed by the routing request, b is the one-hop weight coefficient of the radio node, and Hop wr is the number of hops of the buoy node or air node passed by the routing request;

[0027] Introduce the underwater acoustic transmission link stability factor RQ, and the calculation formula is as follows:

[0028]

[0029] In the formula, d is the distance between two underwater nodes, R represents the maximum underwater acoustic communication radius, w is the distance threshold coefficient, 0 < w < 1, and w × R represents the communication critical distance;

[0030] The total support value ALLRQ is the sum of the total RQ of radio and underwater acoustic communications on the path, and is expressed as:

[0031]

[0032] Where ALLRQ is the total support value, i represents the i-th node of the path, n represents the total number of nodes in the path, and RQ i represents the transmission link stability factor of the i-th node;

[0033] The average link quality (AVGRQ) is the ratio of the sum of all link stability factors in the path to the number of hops. The calculation formula is as follows:

[0034]

[0035] Where n represents the total number of nodes in the path. The larger the AVGRQ value, the higher the link quality.

[0036] In step (3), the node determines whether it has received an RREQ with the same ID. The judgment process is as follows:

[0037] 1) When a node receives a RREQ, it checks whether there is an ID number in the RREQ record table that is identical to the source node and destination node of the RREQ. If so, the RREQ is discarded.

[0038] 2) When a node receives an RREQ, if it is the first time to receive the RREQ, it stores the RREQ ID number and the source node and destination node addresses of the RREQ in the RREQ record table.

[0039] In step (4), the node determines whether it is the destination node or whether there is a path to the destination node. The determination method is: whether the destination node IP address in the RREQ is the same as the IP address of the node;

[0040] The method for determining whether there is a path to the destination node is as follows: determining whether the routing table stores a path to the destination node;

[0041] In step (6), the information received from the underwater acoustic / radio interface is judged to be the information received by the underwater acoustic device or the radio device, and the node type is judged according to the IP address of the destination node;

[0042] In step (7), the node type is determined based on the node's IP address.

[0043] Further, the routing reply includes:

[0044] (1) If a network node receives a RREP packet, it determines whether there is a RREP packet with the same ID and the same destination node in the message list. The determination process for the RREP packet with the same ID is as follows: first determine whether there is the same RREQ ID number and the source node and destination node of the RREQ in the RREQ record table. If so, discard the RREQ; if it is the first time to receive the RREQ, store the RREQ ID number and the source node and destination node address of the RREQ in the RREQ record table; if not, update the destination node routing table and start periodically broadcasting HELLO packets; if there is a RREP packet with the same ID and the same destination node in the message list, read the AVGRQ in the RREP and determine whether it is greater than the AVGRQ value in the existing routing table. If not, discard the RREP packet; if it is greater than the AVGRQ value in the existing routing table, update the destination node routing table and start periodically broadcasting HELLO packets;

[0045] (2) Determine whether the node is a source node, and then determine whether the source node address in the RREP data packet is the local address. If they are the same, it is the source node; if so, the route establishment is completed; if not, unicast forward the RREP to the source node, and the next hop node continues to execute step (1).

[0046] Furthermore, after the route is established, each node on the path periodically broadcasts a Hello packet and begins executing the route maintenance steps, which include:

[0047] (1) The node determines whether it has received a Hello packet from a neighbor node regularly;

[0048] (2) If a Hello packet is received regularly from a neighboring node, no processing is done on the routing table;

[0049] (3) If the Hello packet from a neighboring node is not received regularly, determine whether there is a route in the routing table whose next hop is the neighboring node; if not, execute step (2); if so, delete the route and send a routing error RERR packet to the source node of the route;

[0050] (4) After receiving the RERR packet, the node determines whether there is an erroneous route in its routing table. If not, no processing is done on the routing table. If so, the route is deleted.

[0051] (5) The node determines whether there is still a route in its routing table; if not, it stops periodically broadcasting Hello packets; if so, it determines whether the node is the source node. If the node is not the source node, it unicasts the RERR to the source node; if the node is the source node, the routing maintenance process ends.

[0052] In step (1), the process of a node determining whether it has received a Hello packet from a neighbor node regularly is as follows: the node is set to broadcast a Hello packet every T seconds, and determines whether it has received a Hello packet from the neighbor node within every 2T seconds;

[0053] In step (3), based on the IP address of the neighboring node, the next hop IP address of each path in the routing table is retrieved to see if it is the same as the IP address of the neighboring node;

[0054] In step (4), the destination node and next hop information of the path in the routing table are retrieved to see whether they are consistent with the information in the RERR packet.

[0055] In step (5), to determine whether there are still routes in its own routing table, determine whether the number of paths currently existing in the routing table is 0; to determine whether the node is a source node, determine whether it has the previous hop address of the path. If so, it is not the source node; if not, it is the source node.

[0056] Combining all the above technical solutions, the advantages and positive effects of the present invention are as follows: in response to the problems of one-way transmission, high overhead, and poor adaptability to underwater environments in the current routing algorithms in marine cross-media acoustic-radio collaborative networks, the present invention proposes an optimized AODV Protocol for Cross-media Acoustic-wireless radio Collaborative Networks (CACN-OAODV) based on the traditional wireless ad hoc on-demand distance vector routing protocol (AODV). The protocol takes into account the characteristics of both underwater acoustic and radio communication modes, improves the routing establishment and maintenance mechanism, introduces acoustic-radio weighted hop count and link stability factor, and solves the problems of underwater propagation collision caused by excessive traditional AODV notification packets, and low packet delivery rate and large delay caused by the principle of minimum hop count, thereby reducing network delay and improving the packet delivery rate and throughput of the integrated network.

[0057] The CACN-OAODV protocol of the present invention has advantages over AODV in terms of packet delivery rate, throughput and delay. In the underwater to underwater node data transmission scenario, the CACN-OAODVV protocol packet delivery rate is improved by about 15%, the average throughput is improved by about 20bps, and the average delay is reduced by about 0.06 seconds. In the underwater to aerial node data transmission scenario, the CACN-OAODV protocol packet delivery rate is improved by about 9%, the average throughput is improved by about 12bps, and the average delay is reduced by about 0.24 seconds.

[0058] This invention belongs to the field of marine cross-media acoustic-electric cooperative network communication technology, specifically to a communication ad hoc routing protocol within a marine cross-media acoustic-electric cooperative network. This technical field is extremely important for the real-time sharing of marine information, the exploration and development of marine resources, marine environmental monitoring, and marine safety. Expected benefits include promoting real-time sharing of marine information and driving the innovative development of marine technology. It holds significant value in marine scientific research and resource development, marine environmental monitoring and protection, and marine safety.

[0059] The problems existing in the prior art mainly include that most routing strategies for networking different media separately can only realize one-way transmission from underwater to surface, or the source node needs to obtain the location information of the destination node before sending data, which makes practical application difficult; and most of the integrated networking routing currently directly applies the traditional radio self-organizing network routing algorithm to the acoustic-electric collaborative network, which has problems such as high overhead, adaptability to underwater environments, and poor adaptability when communication nodes move. The present invention effectively solves these problems. By improving the AODV routing method, two-way communication across media nodes is realized, and there is no need to obtain the location information of the destination node before the source node sends data. At the same time, the method also reduces network overhead and improves adaptability to underwater environments by optimizing routing algorithms and introducing link stability factors and other technical means.

[0060] The present invention introduces a number of innovative technologies in key steps such as route search, route reply, and route maintenance. These innovative technologies enable the present invention to overcome the limitations of existing technologies and achieve two-way communication across media nodes, without the need to obtain the location information of the destination node before the source node sends data. At the same time, the method also reduces network overhead and improves adaptability to underwater environments by optimizing routing algorithms and introducing link stability factors and other technical means. Through actual testing and experimental verification, the present invention has demonstrated good stability and reliability in cross-media communications, proving its effectiveness in overcoming technical biases. Compared with existing technologies, the present invention has achieved significant advantages in communication efficiency, network overhead, and adaptability to underwater environments.

[0061] In summary, the technical solution of the present invention has indeed overcome technical prejudice and made important contributions to the development of the field of marine cross-medium acoustic and electrical collaborative network communication technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure;

[0063] Figure 1 This is a flow chart of an improved AODV routing method for an ocean cross-medium acoustic-electric collaborative network provided by an embodiment of the present invention;

[0064] Figure 2 This is a CACN-OAODV route search flow chart provided by an embodiment of the present invention;

[0065] Figure 3 This is a CACN-OAODV routing reply flow chart provided by an embodiment of the present invention;

[0066] Figure 4 This is a CACN-OAODV routing maintenance flow chart provided by an embodiment of the present invention;

[0067] Figure 5 This is a topological diagram of an acoustic-electric collaborative network simulation scenario provided by an embodiment of the present invention;

[0068] Figure 6 This is a simulation result diagram of radio node hop weight selection provided by an embodiment of the present invention;

[0069] Figure 7 is a graph showing the relationship between underwater acoustic packet delivery rate and inter-node distance provided by an embodiment of the present invention;

[0070] Figure 8 is a graph showing the relationship between radio packet delivery rate and inter-node distance provided by an embodiment of the present invention;

[0071] Figure 9 Schematic diagram of underwater-underwater transmission packet delivery rate provided by an embodiment of the present invention;

[0072] Figure 10 Schematic diagram of underwater-to-air transmission packet delivery rate provided by an embodiment of the present invention;

[0073] Figure 11 2 is a schematic diagram of underwater-underwater transmission throughput provided by an embodiment of the present invention;

[0074] Figure 12 2 is a schematic diagram of underwater-to-air transmission throughput provided by an embodiment of the present invention;

[0075] Figure 13 Schematic diagram of underwater-underwater transmission delay provided by an embodiment of the present invention;

[0076] Figure 14 Schematic diagram of underwater-to-air transmission delay provided by an embodiment of the present invention;

[0077] Figure 15 This is a topology diagram of the acoustic-electrical collaborative network provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0078] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0079] The marine cross-medium acoustic-electric cooperative network can be regarded as a heterogeneous mobile self-organizing network. There are three types of nodes in the network: aerial nodes, surface cross-medium nodes, and underwater nodes. Nodes on and above the sea surface use radio for communication, underwater nodes use underwater acoustics for communication, and surface cross-medium nodes have both radio and underwater acoustic communication functions to achieve cross-medium communication. All nodes are mobile, and different types of nodes have different moving speeds. The topology of the acoustic-electric cooperative network is as follows: Figure 15 Directly applying the traditional AODV routing protocol to the ocean cross-media acoustic and electrical collaborative network has the following problems:

[0080] First, when the source node sends data to the target node, it first establishes a path to the destination node through the AODV protocol routing discovery process. Each node stores the routing information in its own routing table, and a lifetime is set for each route in the routing table. If the route exceeds the lifetime, each node will delete the route from the routing table. The source node needs to re-initiate the routing request. If the route does not change, the information exchange in the routing process will lead to a waste of bandwidth and energy. At the same time, since the delay of underwater acoustic communication is longer than that of radio communication, this will also aggravate the conflict of underwater acoustic nodes. In addition, in the traditional AODV protocol, all nodes will broadcast Hello packets for route maintenance. Even if the node is not on the transmission path, the Hello packet will be broadcast, which increases the burden on the underwater acoustic channel, resulting in a decrease in the data packet transmission rate of the entire acoustic-electric collaborative network.

[0081] Second, the traditional AODV protocol is based on the principle of minimum hop count. When a routing request is first initiated, the hop count is set to a minimum initial value. If no routing reply message is received within the set waiting time, the source node increases the lifetime and continues to send routing requests. Because radio transmission speeds are much higher than underwater acoustics, the minimum hop count in an acoustic-electric collaborative network does not equate to minimum latency. Therefore, the transmission speeds and latency of radio and underwater acoustics must be considered in an acoustic-electric collaborative network to reduce overall transmission latency.

[0082] Third, the locations of each node in the acoustic-electric collaborative network are in a state of dynamic change. In the marine environment, communication links are prone to breakage, especially when the intermediate node is located at the communication boundary of the adjacent node, the communication link is even more unstable. Once a break occurs, the route needs to be re-established, which affects the overall network transmission efficiency. Therefore, choosing a stable route is particularly important in the marine environment. When establishing a route, the distance between nodes can be considered to improve packet delivery rate and throughput.

[0083] The present invention solves the data packet collision problem caused by too many routing notification packets in the traditional AODV protocol. In the traditional AODV protocol, each node will set the routing validity period after the route is established, and continuously send routing notification packets during this period to maintain the routing status. However, this method will cause packet collision problems when data is transmitted underwater, increasing the network burden. In addition, in the traditional AODV protocol, when a cross-media node receives a routing request, it may forward the request indiscriminately, resulting in unnecessary network overhead. The present invention no longer sets the routing validity period, but relies on the HELLO packets broadcast regularly by the node to determine whether the route is invalid, thereby effectively reducing the sending of routing notification packets and reducing the risk of data packet collision. And by introducing a cross-media node intelligent data transmission mechanism, the corresponding equipment is selected for data transmission according to the type of destination node (air or underwater), effectively reducing underwater overhead and improving communication efficiency.

[0084] The present invention solves the problem of large transmission delay and unstable link. Due to the large difference in transmission speed between underwater acoustics and radio, the traditional AODV protocol may increase the delay during route discovery due to too many hops. In addition, the traditional AODV protocol does not fully consider the stability of the link when establishing the route, resulting in the link being easily disconnected in harsh environments (such as underwater), affecting the communication quality. The present invention introduces a weighted hop design to weight the hops according to the transmission speed of underwater acoustics and radio, thereby speeding up the route discovery speed and reducing the delay. And by introducing a link stability factor, the stability of the link is evaluated when the route is established, so that a more stable routing path is selected, thereby improving the reliability and stability of communication.

[0085] The core innovation of the present invention is: dynamic routing failure judgment and HELLO packet optimization;

[0086] Dynamic route failure judgment: Abandoning the traditional route validity period setting, the route failure is judged by whether the node can receive the HELLO packets broadcast regularly by the neighbor. This innovation improves the dynamics and accuracy of route judgment.

[0087] HELLO packet optimization: HELLO packets are sent periodically for route maintenance only after a node has established a route. Nodes that have not established a route do not send HELLO packets. This strategy significantly reduces overall information interaction and alleviates the communication burden.

[0088] The second core innovation of the present invention: intelligent data transmission across media nodes;

[0089] Destination node type-guided data transmission: Based on the type of destination node (air or underwater), cross-medium nodes can intelligently choose to transmit data via radio equipment or underwater acoustic equipment. This innovation effectively reduces underwater overhead and improves communication efficiency.

[0090] The third core innovation of the present invention: weighted hop count design;

[0091] Hop-weighted design: A lifetime, or maximum hop count, is set in the route request packet (RREQ). Hop counts are weighted based on the transmission speed differences between underwater acoustic and radio. A hop weight for the buoy's radio equipment is lower, while a hop weight for underwater acoustic equipment is higher. This design speeds up route discovery and translates the minimum hop count into the minimum latency.

[0092] The fourth core innovation of the present invention: introduction of link stability factor;

[0093] Link stability factor: Link stability factors for radio and underwater acoustic transmission are introduced during route establishment. By evaluating link stability, route selection is optimized, improving route stability and packet delivery rate, and effectively addressing issues such as large transmission delays and unstable links.

[0094] The innovative features of the present invention can be divided into:

[0095] 1. To address the problem of excessive routing notification packets in the traditional AODV protocol, which causes data collisions during underwater transmission, the proposed method first eliminates the need for node-specific validity periods after establishing a route. Instead, each node can determine route expiration by receiving HELLO packets regularly broadcast by its neighbors. Second, in the acoustic-electric collaborative routing protocol, a surface cross-medium node specifies the appropriate device for data transmission based on the type of destination node. When the cross-medium node's underwater acoustic device receives a routing request message, if the destination node is an airborne node, it forwards the message directly via the buoy's radio, bypassing the underwater acoustic device's forwarding process, thereby reducing underwater overhead. If the destination node is an underwater node, there are two scenarios: if the surface cross-medium node receives a routing request from an underwater node, it forwards the routing request via its radio; if the surface cross-medium node's radio receives the routing request, it forwards the routing request simultaneously via its underwater acoustic and radio devices. Third, after a node receives a routing response and establishes a route, it is scheduled to send HELLO packets for route maintenance. Other nodes for which a route has not yet been established do not send HELLO packets, thus reducing overall information exchange and alleviating communication overhead. Finally, after receiving the routing request, the underwater destination node sends two consecutive routing responses (RREPs) to the source node to improve the success rate of routing establishment under unreliable communication links.

[0096] 2. To address the issues of long transmission delays and unstable links, there are two innovations.

[0097] (1) Set a lifetime in the route request packet (RREQ), which is the maximum number of hops that the route request packet goes through. If the number of hops that the route request packet goes through exceeds this maximum hop value, the route request packet will not be forwarded. Due to the large difference in transmission speed between underwater acoustic and radio, in order to convert the minimum hop number into the minimum delay and speed up the route discovery speed, the hop number can be weighted. The hop weight of the buoy radio equipment is low, and the hop weight of the underwater acoustic equipment is high. The number of hops that the route request goes through is the weighted hop number Hop, and its value is set as follows:

[0098] Hop=a*Hop uw +b*Hop wr (1)

[0099] Where a is the one-hop weight coefficient of the underwater acoustic sensor node, Hop uw is the number of underwater acoustic nodes that the routing request passes through, b is the one-hop weight coefficient of the radio node, and Hop wr The number of buoy nodes or aerial nodes that the routing request passes through; coefficients a and b are obtained through empirical settings or optimization methods;

[0100] Using formula (1), the number of hops can be made positively correlated with the delay. Since the transmission speeds of underwater acoustic and radio in the acoustic-electric collaborative network are different, the traditional number of hops cannot be positively correlated with the delay, and the minimum number of hops does not necessarily correspond to the minimum delay. Through the design of hop weighting, the number of hops is made positively correlated with the delay.

[0101] (2) When establishing a route, introduce the link stability factors of radio and underwater acoustic transmissions to increase the stability of the route and improve the packet delivery rate.

[0102] Introduce the single-hop link stability factor RQ of underwater acoustic transmission. The calculation formula is as follows:

[0103]

[0104] In the formula, d is the distance between two underwater nodes, R represents the maximum communication radius of underwater acoustic, w is the distance threshold coefficient; 0 < w < 1, w×R represents the critical communication distance. Beyond this distance, the communication link is unstable and packet loss will occur. The radio transmission link stability factor can also use the same expression, except that the coefficient w in the two communication link stability factors is different.

[0105] Formula (2)尽可能的解决了声电协同网络路径上存在两点处在临界通信范围的情况,与公式(3)联合使用,使声电协同网络建立的路径更稳定,尽量不出现路径上两点处在临界通信范围的情况,使源节点到目的节点的路径最稳定。

[0106] The total support value (ALLRQ) is the sum of the RQs of radio and underwater acoustic communications on this path.

[0107]

[0108] In the formula, ALLRQ is the total support value, i represents the i-th node of the path, n represents the total number of nodes in the path, and RQ i represents the transmission link stability factor of the i-th node;

[0109] Formula (3)尽可能的解决了声电协同网络路径上存在两点处在临界通信范围的情况,与公式(2)联合使用。利用公式(3)计算路径上所有节点的链路稳定因子的和,使声电协同网络建立的路径更稳定,尽量不出现路径上两点处在临界通信范围的情况,使源节点到目的节点的路径最稳定。

[0110] If a path contains multiple hop nodes, then when considering the definition of path quality, the number of hops needs to be considered. The average link quality (AVGRQ) is the ratio of the sum of all link stability factors in the path to the number of hops. The formula is as follows. The larger the AVGRQ value, the higher the link quality.

[0111]

[0112] Where n represents the total number of nodes in the path. The larger the AVGRQ value, the higher the link quality.

[0113] Formula (4) minimizes the situation where two points on the path of the acoustic-electric collaborative network are within the critical communication range, optimizing the overall link factor and hop count. It is used in conjunction with Formula (3). Formula (4) is used to calculate the average value of the path link stability factor, making the path established by the acoustic-electric collaborative network have fewer hops and more stable, minimizing the situation where two points on the path are within the critical communication range, and making the path from the source node to the destination node the most stable.

[0114] After the improvement, the routing request must include the coordinate information of the previous hop. The modified message format is shown in Tables 1 and 2. The main innovation is to add "previous hop geographic location information" and "total support value ALLRQ" to the RREQ message, and "average support value (AVGRQ)" to the RREP message. The number of hops in both packets is calculated according to formula (1).

[0115] Table 1 Route Request (RREQ) packet format

[0116]

[0117] Table 2 Route Reply (RREP) packet format

[0118]

[0119] In a cross-media transmission scenario, when an underwater node sends data to a destination node, it checks whether a route exists to the destination node. If so, the data is sent directly. If not, the source node sends a route request (RREQ) to establish a route. The route request packet contains a time-to-live (TTL) hop count. If no route response is received for an extended period, the route request is sent again with an increased time-to-live hop count.

[0120] When other nodes receive a routing request, they first determine whether the TTL of the routing request is finite. If not, they discard it. If so, they calculate the distance between the current node and the previous hop node and the single-hop link stability factor (RQ). They add this RQ value to the total support value (ALLRQ) in the RREQ and divide it by the number of hops to obtain the average link quality (AVGRQ). The node then determines whether it has received an RREQ with the same ID. If not, it directly stores or updates the path to the source node in the routing table. If so, it determines whether the AVGRQ is greater than the value in the existing routing table. If so, it stores or updates the path to the source node in the routing table. Otherwise, it discards the routing request.

[0121] The node then determines whether it is the destination node or whether a path to the destination node exists. If it is not the destination node or no path to the destination node exists, if the node is a buoy node, it determines whether it has received a RREQ from an underwater acoustic device. If it has, it requests a routing request with the survival hop count minus b, and continues broadcasting the RREQ via radio. If it has not received a RREQ from an underwater acoustic device, it determines whether the destination node is an underwater node. If it is not, it requests a routing request with the survival hop count minus b, and continues broadcasting the RREQ via radio. If it is an underwater node, it requests a routing request with the survival hop count minus b, continues broadcasting the RREQ via radio, and simultaneously requests a routing request with the survival hop count minus a, and continues broadcasting the RREQ via underwater acoustics. If it is not a buoy node, it determines whether it is an underwater acoustic node. If it is, it requests a routing request with the survival hop count minus a, and continues broadcasting the RREQ via underwater acoustics. If it is an airborne node, it requests a routing request with the survival hop count minus b, and continues broadcasting the RREQ via radio.

[0122] If the node is the destination node or there is a path to the destination node, two routing response RREPs are sent to the source node.

[0123] If a network node receives an RREP packet, it determines whether there is an RREP packet with the same ID and destination node in the message list. If not, it updates the destination node's routing table and begins periodically broadcasting HELLO packets. If so, it reads the AVGRQ value in the RREP packet and determines whether it is greater than the AVGRQ value in the existing routing table. If not, it discards the RREP packet. If so, it updates the destination node's routing table and begins periodically broadcasting HELLO packets. It then determines whether the node is the source node. If so, the route is established. If not, it unicasts the RREP packet to the source node.

[0124] The above process enables efficient communication between underwater nodes, surface buoy nodes, and aerial platforms in ocean cross-media communications. This reduces underwater communication overhead and improves communication efficiency. It also accelerates route discovery, reduces latency, improves routing stability and packet delivery rates, and enhances network reliability. This addresses the high overhead, high latency, and unstable links associated with traditional routing protocols in ocean cross-media networks.

[0125] like Figure 1 As shown, the improved AODV routing method for the marine cross-media acoustic and electrical cooperative network provided by the embodiment of the present invention consists of search, route reply and route maintenance processes.

[0126] S1, when establishing a route, introduces the link stability factor of radio and underwater acoustic transmission; after the route is established, each node determines whether the route is invalid by whether it can receive the HELLO packets broadcast regularly by its neighbors;

[0127] In step S2, the surface cross-medium node specifies relevant equipment for data transmission based on the type of the destination node. When the cross-medium node's underwater acoustic equipment receives a routing request, if the destination node is an airborne node, it directly forwards the request via the buoy's radio equipment. If the destination node is an underwater node, if the surface cross-medium node receives a routing request from the underwater node, it forwards the routing request via its radio equipment. If the surface cross-medium node's radio equipment receives a routing request, it forwards the routing request simultaneously via the underwater acoustic equipment and the radio equipment.

[0128] S3, after the node receives the routing response and establishes the route, it sets a timer to send HELLO packets for route maintenance. Other nodes that have not established routes do not send HELLO packets;

[0129] S4, after receiving the routing request, the underwater destination node sends two routing responses to the source node in succession.

[0130] like Figure 2 As shown, the routing search process provided by the embodiment of the present invention is as follows:

[0131] 1. When a source node needs to send data to a destination node, it checks whether a route exists to the destination node. If yes, it sends the data directly. If no, it sends a route request (RREQ) to establish the route. The route request packet contains a time-to-live (TTL) number of hops. If no route response is received for a long time, the route request is sent again with an increased time-to-live (TTL) number of hops.

[0132] 2. When a node receives a routing request, it first determines whether the TTL of the routing request is a finite value. If not, it discards the request. If so, it calculates the distance between the node and the previous hop node and the single-hop link stability factor (RQ). It then adds this RQ value to the total support value (ALLRQ) in the RREQ and divides the result by the number of hops to obtain the average link quality (AVGRQ).

[0133] 3. The node determines whether it has received an RREQ with the same ID. If not, it directly stores or updates the path to the source node in the routing table. If so, it determines whether AVGRQ is greater than the value in the existing routing table. If so, it stores or updates the path to the source node in the routing table. Otherwise, it discards the routing request.

[0134] 4. The node determines whether it is the destination node or there is a path to the destination node. If so, it sends two routing response RREPs to the source node. When the source node receives the RREP, the route establishment is completed.

[0135] 5. If not, determine whether the node is a buoy node;

[0136] 6. If so, determine whether the node has received an RREQ from the underwater acoustic device. If so, subtract b from the routing request survival hop count TTL, and the node continues to broadcast the RREQ via radio. The next hop node continues to execute step 2. If not, determine whether the destination node is an underwater node. If not, subtract b from the routing request survival hop count TTL, and broadcast the RREQ via radio. The next hop node continues to execute step 2. If so, subtract b from the routing request survival hop count TTL, and continue to broadcast the RREQ via radio. At the same time, subtract a from the node's routing request survival hop count TTL, and continue to broadcast the RREQ via underwater acoustics. The next hop node continues to execute step 2.

[0137] 7. If not, determine whether the node is an underwater acoustic node. If so, the node requests the survival hop count TTL minus a, continues to broadcast RREQ using underwater acoustics, and the next hop node continues to execute step 2. If not, the node routing request survival hop count TTL minus b, uses radio to broadcast RREQ, and the next hop node continues to execute step 2.

[0138] like Figure 3 As shown, the routing reply process provided by the embodiment of the present invention is as follows:

[0139] 1. If a network node receives an RREP packet, it checks whether there is an RREP packet with the same ID and the same destination node in the message list. If not, it updates the destination node's routing table and begins periodically broadcasting HELLO packets. If so, it reads the AVGRQ value in the RREP packet and determines whether it is greater than the AVGRQ value in the existing routing table. If not, it discards the RREP packet. If so, it updates the destination node's routing table and begins periodically broadcasting HELLO packets.

[0140] 2. Determine whether the node is the source node. If so, the route is established. If not, unicast the RREP to the source node, and the next hop node continues to execute step 1.

[0141] After the route is established, each node on the path broadcasts Hello packets regularly and starts executing the route maintenance process. Figure 4 As shown, the route maintenance process provided by the embodiment of the present invention is as follows:

[0142] 1. The node determines whether it has received Hello packets from a neighbor node regularly;

[0143] 2. If yes, do nothing with the routing table;

[0144] 3. If not, determine whether there is a route in the routing table whose next hop is the neighbor node; if not, execute step 2; if so, delete the route and send a routing error RERR packet to the source node of the route.

[0145] 4. Upon receiving the RERR packet, the node determines whether the erroneous route in the RERR packet exists in its routing table. If not, no action is taken on the routing table; if so, the route is deleted.

[0146] 5. The node determines whether the route still exists in its routing table. If not, it stops periodically broadcasting Hello packets. If so, it determines whether it is the source node. If not, it unicasts the RERR to the source node. If so, the route maintenance process ends.

[0147] In order to further demonstrate the positive effects of the above embodiment, the present invention conducts the following experiments based on the above technical solution.

[0148] In order to describe the advantages of this routing protocol, a simulation scenario topology is constructed as follows: Figure 5 As shown, the network has a total of 28 underwater nodes, 6 sea surface buoy nodes, and 3 aerial nodes. The topological structure of each node is shown in the figure 5 The specific simulation parameter settings are shown in Table 3.

[0149] Table 3 Simulation parameter settings

[0150]

[0151]

[0152] This paper simulates the network performance of the aforementioned acoustic-electric collaborative network using the traditional AODV and CACN-OAODV routing protocols in two transmission scenarios. The two scenarios are: the source and destination nodes are both located 1000 meters underwater; and the source node is located 1000 meters underwater and the destination node is in the air. This paper analyzes the latency, throughput, and packet delivery rate performance of different routing protocols in these two scenarios.

[0153] The weight coefficients a and b in the weighted hop count in the CACN-OAODV routing protocol, and the critical communication distance w×R in the stability factor of the underwater acoustic and radio transmission links are determined by simulation experience values ​​in the present invention.

[0154] Since the transmission speed of radio is much faster than underwater acoustic, the underwater acoustic node hop weight a is set to 1; the radio node hop weight b is set to 0.25, 0.5, 0.75, and 1 respectively. The simulation test of route establishment time is carried out and the establishment time of acoustic-electric collaborative routing with different radio hop weights is recorded. The simulation results are shown in the figure below. Figure 6 As shown in FIG, when b=0.5, the route establishment time is the lowest, so b is set to 0.5 in the example.

[0155] Regardless of underwater acoustic communication or radio communication, the point-to-point packet delivery rate cannot reach 100% at the critical distance. Next, the critical distance of the two communication methods is simulated to determine the w value in the link stability factor of the two communication methods. The critical distance of the two nodes using underwater acoustic and radio communication methods is simulated, and 900 data are sent. The simulation results of the data packet delivery rate are as follows: Figure 7 and Figure 8 shown.

[0156] like Figure 7 As shown in the figure, the maximum communication radius R of underwater acoustic transmission is 2200m. When it exceeds 2000m, packet loss begins to occur. Therefore, the critical distance is 2000m, corresponding to w of about 0.91, so w = 0.91 is set. The link stability factor in the underwater acoustic transmission link is:

[0157]

[0158] like Figure 8 As shown in the figure, the maximum radio communication radius is 7800m. When the distance between two nodes exceeds 7600m, packet loss begins to occur. Therefore, the critical distance is 7600m, corresponding to w of approximately 0.97, so w = 0.97 is set. In this regard, the link stability factor in the radio transmission link is calculated as follows:

[0159]

[0160] After setting the above parameters, we will analyze the network latency, throughput, and packet delivery rate performance indicators of the traditional AODV and CACN-OAODV routing protocols in the underwater node-underwater node and underwater node-aerial node scenarios.

[0161] a. Packet delivery rate: The packet delivery rate in the above two scenarios is as follows Figure 9 and Figure 10 As shown in the figure, the CACN-OAODV routing protocol has a higher packet delivery rate than the AODV protocol in both scenarios. The underwater-to-underwater transmission scenario is approximately 15% higher than traditional AODV, and the underwater-to-air scenario is approximately 9% higher. This is because the improved AODV routing protocol effectively controls the number of routed packets, reducing the probability of channel collisions in the underwater acoustic channel space. Furthermore, the destination node replies to the RREP twice, accelerating the establishment of the data transmission path. The distance between nodes is also taken into account during path establishment, improving the stability of route establishment and thereby increasing the packet reception rate at the destination node.

[0162] b. Throughput: The throughput in the above two scenarios is as follows Figure 11 and Figure 12As shown in the figure, the CACN-OAODV routing protocol achieves higher throughput than AODV in both scenarios. In the underwater-underwater transmission scenario, it is approximately 20 bps higher than traditional AODV, and in the underwater-to-air transmission scenario, it is approximately 12 bps higher than the original AODV. During the first 100 seconds of the simulation, throughput fluctuates significantly because the path is not yet fully established. After 100 seconds, throughput gradually stabilizes, but subsequent fluctuations are due to path disruptions caused by node movement, necessitating path reestablishment, which results in temporary throughput fluctuations. In the later stages of the simulation, it is clear that CACN-OAODV outperforms traditional AODV.

[0163] c. Delay: as shown in Table 4;

[0164] Table 4 Average underwater-underwater and underwater-air transmission delays

[0165] Average delay (s) Underwater-Underwater Underwater-Aerial AODV 2.64 1.83 CACN-OAODV 2.58 1.59

[0166] The delay in the above two scenarios is as follows Figure 13 and Figure 14 The average latency is shown in Table 4. In both scenarios, the CACN-OAODV routing protocol achieved lower latency than the AODV protocol, approximately 0.06 seconds lower in the underwater-underwater transmission scenario and approximately 0.24 seconds lower in the underwater-to-air transmission scenario. Compared to the unmodified AODV routing protocol, the improved AODV routing protocol significantly reduced the number of significant delays. This is because the destination node responds twice to the routing request, expediting the establishment of the data transmission path and reducing packet buffering time. Furthermore, the number of survivable hops corresponding to the sending device during the routing request is reduced, making the link more likely to pass through the underwater-radio-underwater link, accelerating transmission speed and reducing transmission latency.

[0167] Simulation analysis shows that the CACN-OAODV protocol outperforms AODV in terms of packet delivery rate, throughput, and latency. In underwater-to-underwater node data transmission scenarios, the CACN-OAODV protocol improves packet delivery rate by approximately 15%, throughput by an average of approximately 20 bits per second, and latency by an average of approximately 0.06 seconds. In underwater-to-air node data transmission scenarios, the CACN-OAODV protocol improves packet delivery rate by approximately 9%, throughput by an average of approximately 12 bits per second, and latency by an average of approximately 0.24 seconds.

[0168] The above description is only a preferred specific implementation method of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. An improved AODV routing method for ocean cross-media acoustic and electrical cooperative network, characterized in that: The method includes route finding, route replying and route maintenance; When establishing a route, the link stability factor of radio and underwater acoustic transmission is introduced. After the route is established, each node determines whether the route is invalid by whether it can receive the HELLO packets broadcast regularly by its neighbors. The surface node selects the corresponding transmission device based on the type of the destination node of the routing request packet RREQ; the type of the destination node includes aerial nodes and underwater nodes. After the surface node receives the routing request, the transmission rules are as follows: (1) The destination node is an air node: Directly forward routing requests through the radio equipment of the surface node, and the underwater acoustic equipment no longer forwards routing requests; (2) The destination node is an underwater node, which can be divided into two cases: (2.i) If the surface node receives a routing request through the underwater acoustic device, it forwards the routing request through the radio device, and the underwater acoustic device no longer forwards the routing request; (2.ii) If the surface node receives a routing request via the radio device, it forwards the routing request via both the underwater acoustic device and the radio device; After the node receives the routing response and establishes the route, it sets a timer to send HELLO packets for route maintenance. Nodes that have not established routes do not send HELLO packets. After receiving the routing request, the underwater destination node sends two consecutive routing responses to the source node; Among them, route search includes: (a) When a source node has data to send to a destination node, the source node checks whether there is a route to the destination node. If so, it sends the data directly; if not, the source node sends a route request packet RREQ to start establishing the route; (b) When a node receives an RREQ, it determines whether the TTL of the routing request is greater than 0. If not, it discards the RREQ. If so, it calculates the distance between the current node and the previous hop node and the single-hop link stability factor RQ. It adds the RQ value to the total support value ALLRQ in the RREQ and divides it by the number of hops to obtain the average link quality AVGRQ, and then proceeds to the next step. (c) The node determines whether it has received a RREQ with the same ID. If not, it directly stores or updates the path to the source node in the routing table and proceeds to the next step. If so, it determines whether AVGRQ is greater than the value in the existing routing table. (ci) If so, it stores or updates the path to the source node in the routing table and proceeds to the next step. (c.ii) If not, it discards the routing request RREQ. (d) The node determines whether it is the destination node or whether there is a path to the destination node. If so, it sends two routing reply packets (RREPs) to the source node. The source node receives the RREPs and the route is established. If not, it proceeds to the next step. (e) If the node is not the destination node or there is no path to the destination node, determine whether the node is a surface node. (f) If the node is a surface node, determine whether the node has received RREQ from the underwater acoustic device. If so, subtract the TTL of the routing request from , the node continues to broadcast RREQ using radio, and the next hop node continues to execute step (b); if not, that is, the node does not receive RREQ from the underwater acoustic device, it determines whether the destination node is an underwater node, (fi) if not, the node routing request survival hop count TTL minus , use radio broadcast RREQ, the next hop node continues to execute step (2); (f.ii) If, that is, the destination node is an underwater node, the node generates two RREQs with different routing request survival hop counts TTL, which are broadcasted through radio and underwater acoustic equipment respectively; the RREQ used for radio equipment broadcast, the node routing request survival hop count TTL minus , used for RREQ broadcast by underwater acoustic equipment, node request survival hop count TTL minus , the next hop node continues to execute step (b); is the one-hop weight coefficient of the node that uses underwater acoustic equipment to transmit information, is the one-hop weight coefficient of the node that uses radio equipment to transmit information; (g) If the node is not a surface node, determine whether the node is an underwater node. (gi) If so, the node requests the survival hop count TTL minus , continue to broadcast RREQ using underwater sound, and the next hop node continues to execute step (2); (g.ii) If not, that is, the node is not an underwater node, the node routing request survival hop count TTL minus ,Using radio broadcast RREQ, the next hop node proceeds to step (b).

2. The improved AODV routing method for ocean cross-media acoustic and electrical cooperative network according to claim 1 is characterized in that: In step (a), the route request data packet RREQ contains the route request survival hop count TTL. If no route response is received for a long time, the survival hop count is increased and the route request is continued to be sent.

3. The improved AODV routing method for ocean cross-media acoustic and electrical cooperative network according to claim 1 is characterized in that: In step (b), the number of hops that the routing request goes through is the weighted hop count , the expression is: ； Where, is the one-hop weight coefficient of the node that uses underwater acoustic equipment to transmit information, is the number of hops through which the routing request passes through nodes that use underwater acoustic equipment to transmit information, is the one-hop weight coefficient of the node using radio equipment to transmit information, The number of hops through which the routing request passes through nodes that use radio equipment to transmit information; Introducing underwater acoustic transmission link stability factor , the calculation formula is as follows: ； In the formula is the distance between two underwater nodes, Indicates the maximum underwater acoustic communication radius, is the distance threshold coefficient, , Indicates the critical distance for communication; The total support value ALLRQ is the total support value of radio and underwater acoustic communication on the routing path. The sum of , the expression is: ； Where, is the total support value, Indicates the path nodes, The total number of nodes representing the path, Indicates the The transmission link stability factor of each node; The average link quality (AVGRQ) is the ratio of the sum of all link stability factors in the path to the number of hops. The calculation formula is as follows: ； Where, Represents the total number of nodes on the path. The larger the AVGRQ value, the higher the link quality.

4. The improved AODV routing method for ocean cross-media acoustic and electrical cooperative network according to claim 1, characterized in that: In step (c), the node determines whether it has received an RREQ with the same ID. The judgment process is as follows: When a node receives an RREQ, it determines whether there is an RREQ with the same ID number, source node, and destination node in its own RREQ record table. The above three conditions must be met at the same time. If so, the RREQ is discarded; if not, the RREQ ID number, source node, and destination node address are stored in the RREQ record table.

5. The improved AODV routing method for ocean cross-media acoustic and electrical cooperative network according to claim 1, characterized in that: In step (d), the method for determining whether it is the destination node is: whether the destination node IP address in the RREQ is the same as the IP address of the local node; the method for determining whether there is a path to the destination node is: whether the routing table stores the path to the destination node; In step (f), the surface node determines whether the information is received by the underwater acoustic device or the radio device according to the information received by the node master from the underwater acoustic or radio interface, and determines the node type of the destination node according to the IP address of the destination node; In step (g), the node type is determined based on the node's IP address.

6. The improved AODV routing method for ocean cross-media acoustic and electrical cooperative network according to claim 1, characterized in that: Routing reply, including: (A) If a network node receives a RREP packet, it determines whether there is a RREP packet with the same ID and the same destination node in the message list. If not, it updates the destination node routing table and starts broadcasting HELLO packets periodically. If there is a RREP packet with the same ID and the same destination node in the message list, it reads the AVGRQ in the RREP and determines whether the value is greater than the AVGRQ value in the existing routing table. If not, it discards the RREP packet. If the value is greater than the AVGRQ value in the existing routing table, it updates the destination node routing table and starts broadcasting HELLO packets periodically. (B) Determine whether the node is the source node. If so, the route is established. If not, unicast the RREP to the source node, and the next hop node continues to execute step (A).

7. The improved AODV routing method for ocean cross-media acoustic and electrical cooperative network according to claim 1, characterized in that: After the route is established, each node on the path periodically broadcasts HELLO packets and begins performing route maintenance, including: (d1) The node determines whether it has received a HELLO packet from a neighbor node regularly; (d2) If yes, do nothing with the routing table; (d3) If not, determine whether there is a route in the routing table with the neighbor node as the next hop. (d3.i) If so, delete the route and send a routing error packet RERR to the source node of the route. (d3.ii) If not, do not do anything to the routing table. (d4) When a node receives a routing error RERR, it determines whether there is an erroneous route in its own routing table. If so, it deletes the route and executes the next step. If not, it does not process the routing table. (d5) The node determines whether there is still a route in its routing table; if not, it stops periodically broadcasting HELLO packets; if so, it determines whether the node is the source node. (d5.i) If the node is not the source node, it unicasts the RERR to the source node; (d5.ii) If the node is the source node, it ends the routing maintenance process.

8. The improved AODV routing method for ocean cross-media acoustic and electrical cooperative network according to claim 7, characterized in that: In step (d1), the method for a node to determine whether it has received a HELLO packet from a neighbor node regularly is as follows: the node sets T Broadcast HELLO packet once per second, judgment 2 T Whether the HELLO packet from the neighboring node is received within seconds; In step (d3), the method for determining whether there is a route in the routing table whose next hop is a neighbor node is as follows: searching the routing table to see whether the IP address of the next hop of each path is the same as the IP address of the neighbor node; In step (d4), the method for determining whether there is an erroneous route in the RERR packet in the own routing table is to retrieve the destination node and next hop node information of the path in the routing table to see whether they are consistent with the information in the RERR packet.

9. The improved AODV routing method for ocean cross-media acoustic and electrical cooperative network according to claim 7, characterized in that: In step (d5), the method for determining whether there are still routes in its own routing table is: determine whether the number of paths currently existing in the routing table is 0. If it is 0, it means there is no route; the method for determining whether the node is a source node is: determine whether it has the previous hop address of the path. If so, it is not the source node; if not, it is the source node.

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