Underwater sound opportunistic routing method based on directional transmission

Abstract

The invention discloses an underwater acoustic opportunistic routing protocol method based on directional transmission. A traditional underwater acoustic opportunistic routing protocol adopts an omni-directional transmission mode, the problem of high data packet redundancy rate exists, and the phenomena of bypassing a far path and routing voids are easy to occur in a local sparse region, so that the network throughput is reduced and the energy consumption is increased. Based on the defects, a beam forming technology of a directional transducer is introduced, so that a sending node can directionally align to a target node to forward data, and the network space multiplexing rate is improved. And in combination with the advantage that the transmission distance of the directional transducer is farther under the same transmission power, the occurrence probability of routing voids is reduced, and the transmission delay of the network is reduced. And three factors of depth information, position information and residual energy of the nodes are considered, so that the average life of the network is prolonged. Compared with a traditional routing protocol method based on omnidirectional transmission, the method has the advantage that the performance of an underwater acoustic communication network is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of underwater acoustic communication, and in particular relates to an underwater acoustic opportunity routing method based on directional transmission. Background Art

[0002] With the increasing demand for ocean exploration, the research on Underwater Acoustic Sensor Network (UASN) has broad application prospects and practical significance, and has been a hot topic in recent years. Traditional underwater sensor networks are mainly composed of ground base stations, surface buoy nodes and underwater sensor nodes. The underwater data transmission link is generally from the source node at the bottom of the water to the sensor node and then to the surface buoy node. Due to the diversity and complexity of the underwater environment, underwater acoustic communication has the characteristics of severe noise, limited energy, and extended transmission time compared to radio communication. Therefore, the key technical problem facing underwater acoustic communication at present is how to effectively and reliably forward data to the surface buoy node. The routing protocol plays a key role in this process, determining whether the data packet can be transmitted to the destination node through an efficient and reliable path.

[0003] Existing underwater acoustic routing protocols have made improvements to performance bottlenecks such as routing holes, limited energy, and long transmission delays, but few studies have focused on improving performance by combining directional transducers. Directional transducers can concentrate energy on a small angle. Compared with omnidirectional transmission modes, directional transducers can transmit farther with a smaller beam width when the power is equal, thereby increasing spatial multiplexing and reducing end-to-end delay and energy loss, thereby greatly improving the communication efficiency of underwater acoustic networks. Summary of the invention

[0004] The main purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and provide a hydroacoustic opportunity routing method based on directional transmission.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A hydroacoustic opportunity routing method based on directional transmission is applied to a hydroacoustic sensor network with a multi-hop topology structure, including a source node fixed on the bottom of the water, N relay sensor nodes deployed underwater, and a buoy node deployed on the water surface. The source node contains the location information of the surface buoy node, and each node can obtain and regularly update its own location information through the equipped positioning device, ignoring the position changes of all nodes caused by the external environment. Each node is equipped with a multi-modal directional transducer that can realize beam directional forwarding. The beam angle is controlled by software definition and the beam switching time can be ignored. It is characterized in that the hydroacoustic opportunity routing method includes the following steps: S1, initialization stage, each node in the underwater acoustic sensor network obtains its own location information, the source node periodically generates a data packet, and the current node aligns the direction of the directional beam to the position of the surface buoy node to start sending data packets; S2. After the current node sends the data packet, the nodes that successfully receive the data packet within the transmission range of the current node's directional beam form the forwarding candidate set of the current node. After receiving the data packet, the nodes in the forwarding candidate set extract the packet ID number and the location information of the current node and the surface buoy node; S3, the nodes in the forwarding candidate set determine whether the data packet has been forwarded. If so, the data packet is discarded and forwarding is abandoned; if not, step S4 is executed; S4. The nodes in the forwarding candidate set calculate their respective priority weight factors according to their respective location information and current remaining energy. The larger the priority weight factor, the higher the forwarding priority and the shorter the waiting forwarding time of the node. The nodes in the forwarding candidate set calculate and set the waiting forwarding time according to their respective priority weight factors and enter the waiting holding state while monitoring the channel; S5. The node in the forwarding candidate set in the waiting state determines whether it has received a control packet with the same ID number as the previously received data packet. If so, it abandons the data packet forwarding and returns to the initial listening state to wait for receiving a new packet. If not, it executes step S6. S6. The node with the shortest waiting time in the forwarding candidate set is the node with the highest priority. After the waiting time is over, the node with the highest priority updates the sending node position in the data packet to its own node position. The node forwards the data packet along the direction vector of its own position and the position of the surface buoy node. After the node forwards the data packet, it resets the beam direction to the direction from the current node to the previous hop node and sends a control packet. S7. Determine whether the surface buoy node has received the ID data packet. If so, the transmission of the current ID data packet ends; if not, go to step S2 until the data packet is successfully transmitted from the source node to the surface buoy node.

[0006] Furthermore, in step S1, the model of the directional beam is abstracted as a fan. Under equal power conditions, the transmission distance of the directional beam is farther than that of the omnidirectional beam. In addition to the data information collected by the active node, the data packet also includes the data packet type and ID number, the sending node ID and coordinate information, and the surface buoy node coordinate information.

[0007] The directional transmission mechanism is used because the transmission power can be concentrated at a certain angle to transmit a longer distance, thereby increasing the spatial multiplexing rate and reducing the end-to-end delay. However, since the multi-modal directional transducer realizes beam directional forwarding by weighting multiple different modes, the directivity and power of the beam are controlled by internal software, the control logic is relatively complex and the beam shape is not completely regular. The present invention only needs to change the angle of the beam without changing the beam width, so the beam model is abstracted into a regular fan shape, which is conducive to the selection of candidate set nodes.

[0008] Furthermore, in step S4, the nodes in the forwarding candidate set The priority takes into account the depth difference of the nodes. , the distance difference from the node to the direction vector and the remaining energy of the node The present invention uses the priority weight factor Measuring Nodes The forwarding priority of the The larger the value, the higher the forwarding priority of the node. The value is calculated as follows:

[0009] in, It represents the ratio coefficient of depth difference to distance difference, which can be adjusted according to the specific deployment of network nodes. and The sensitivity is adjusted dynamically. Represents the nodes in the forwarding candidate set The depth difference between the node and the current node. represents the transmission radius of the node, Represents the nodes in the forwarding candidate set The distance difference to the direction vector. represents the current remaining energy of the node, Indicates the initial set energy of the node. The bigger, The smaller, The larger the The larger the value, the higher the priority of the node in the candidate node set.

[0010] The priority weight factor of the node is calculated by comprehensively considering the node depth information, location information and remaining energy in the forwarding candidate set. This is because the node with the larger depth difference and the closer distance direction vector is selected as the next hop forwarding node, the closer the node is to the surface buoy node. The fewer the total number of hops for the data packet to reach the surface buoy node. The nodes with more remaining energy should have more opportunities to participate in data packet forwarding, so that the transmission of data packets will not be interrupted due to the rapid exhaustion of energy due to the frequent participation of some nodes in forwarding.

[0011] Furthermore, in step S4, the waiting forwarding time of the nodes in the forwarding candidate set is Inversely proportional to the priority weight factor:

[0012] The maximum holding time is set, and the higher the priority of the node, the shorter the waiting time. This is because it can ensure that when the node with the largest priority weight factor ends the waiting time first and starts forwarding, the other nodes in the forwarding candidate set are in a waiting holding state.

[0013] Among them, the waiting forwarding time It is inversely proportional to the priority because it ensures that the nodes that are closer to the surface buoy node and have more remaining energy forward the data packet earlier.

[0014] Further, in step S5, the control packet contains the same ID number as the currently forwarded data packet. To ensure that the highest priority node can inhibit other low priority nodes from forwarding the same data packet after successfully forwarding the data packet, for two nodes within the same hop range , The forwarding time must meet the following requirements:

[0015] in, Indicates the waiting time of high priority nodes, Indicates the waiting time of low priority nodes, Indicates a high priority node The time when the data packet is received, Indicates low priority nodes The time when the data packet is received, Indicates that the control packet is from a high priority node Reaching a low priority node The time required for successful reception, that is, the low priority node needs to be guaranteed The control packet is received by the low priority node Receive the low priority node before In the waiting state.

[0016] Furthermore, in step S6, each node The simplified expression of the waiting time is: Each node The simplified expression of the waiting time is:

[0017] in, represents the priority weight factor, represents the transmission radius of the node, represents the speed of sound propagation in water, When the value becomes larger, the waiting time becomes smaller and the end-to-end delay also becomes smaller, but the probability of a node suppressing other low-priority nodes will also decrease, which will lead to relatively higher energy consumption.

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) In order to solve the problem of high data packet redundancy in omnidirectional transmission and the problem of "detour" and routing holes that are easy to appear in local sparse areas, the present invention combines the hydroacoustic opportunity routing protocol method designed with directional transmission mechanism to limit the forwarding area to the fan-shaped area facing the surface buoy node. Nodes outside the fan-shaped area will not participate in the forwarding of data packets, thereby reducing the redundancy of data packets during transmission. At the same time, the transmission distance is farther under the same power, so the network performance in local sparse areas is better; (2) The present invention considers node depth, location information, and node residual energy consumption when selecting forwarding nodes. Through multi-factor joint optimization, the energy load balancing of the network is improved and the network service life is extended. It is suitable for high-latency, low-bandwidth, and node energy-constrained application scenarios of underwater acoustic sensor networks. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 It is a flow chart of a hydroacoustic opportunity routing method based on directional transmission disclosed by the present invention; Figure 2 It is a beam model diagram of a hydroacoustic opportunity routing method based on directional transmission disclosed by the present invention; Figure 3 The invention discloses a method for routing hydroacoustic opportunities based on directional transmission. and Schematic diagram of Figure 4 It is a frame structure diagram of a data packet and a control packet in a hydroacoustic opportunity routing method based on directional transmission disclosed by the present invention; Figure 5 Schematic diagram of the routing process of nodes in the hydroacoustic opportunity routing method based on directional transmission in an embodiment of the present invention; Figure 6is a diagram showing the performance result of data packet delivery rate of a hydroacoustic opportunity routing method based on directional transmission in an embodiment of the present invention, which is simulated using an NS-3 discrete network simulator; Figure 7 This is a graph showing the average end-to-end delay performance result of simulating the hydroacoustic opportunity routing method based on directional transmission in an embodiment of the present invention using the NS-3 discrete network simulator; Figure 8 This is a graph showing the average energy consumption results of nodes simulated using the NS-3 discrete network simulator for the hydroacoustic opportunity routing method based on directional transmission in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0022] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0023] Embodiment 1: like Figure 1 As shown, when the source node has a data packet that needs to be forwarded to the surface buoy node, the forwarding method of the hydroacoustic opportunity routing protocol based on directional transmission disclosed in the present invention is used, and the forwarding method includes the following steps: S1, initialization stage, each node in the underwater acoustic sensor network obtains its own location information, the source node periodically generates a data packet, and the current node aligns the direction of the directional beam to the position of the surface buoy node to start sending data packets; In step S1, the model of the directional beam is abstracted as a fan. Under equal power conditions, the transmission distance of the directional beam is farther than that of the omnidirectional beam. In addition to the data information collected by the active node, the data packet also includes the data packet type and ID number, the sending node ID and coordinate information, and the surface buoy node coordinate information.

[0024] S2. After the current node sends the data packet, the nodes that successfully receive the data packet within the transmission range of the current node's directional beam form the forwarding candidate set of the current node. After receiving the data packet, the nodes in the forwarding candidate set extract the packet ID number and the location information of the current node and the surface buoy node; S3, the nodes in the forwarding candidate set determine whether the data packet has been forwarded. If so, the data packet is discarded and forwarding is abandoned; if not, step S4 is executed; S4. The nodes in the forwarding candidate set calculate their respective priority weight factors according to their respective location information and current remaining energy. The larger the priority weight factor, the higher the forwarding priority and the shorter the waiting forwarding time of the node. The nodes in the forwarding candidate set calculate and set the waiting forwarding time according to their respective priority weight factors and enter the waiting holding state while monitoring the channel; In step S4, the nodes in the forwarding candidate set The priority takes into account the depth difference of the nodes. , the distance difference from the node to the direction vector And the remaining energy of the node. The present invention uses the priority weight factor Measuring Nodes The forwarding priority of the The larger the value, the higher the forwarding priority of the node. The value is calculated as follows:

[0025] in, It represents the ratio coefficient of depth difference to distance difference, which can be adjusted according to the specific deployment of network nodes. and The sensitivity is adjusted dynamically. Indicates the nodes within the beam range The depth difference between the forwarding nodes, represents the transmission radius of the node, Indicates the nodes within the beam range The distance difference to the direction vector. represents the current remaining energy of the node, Indicates the initial set energy of the node. The bigger, The smaller, The larger the The larger the value, the higher the priority of the node in the candidate node set. Inversely proportional to the priority weight factor:

[0026] The maximum holding time is set. The higher the priority of the node, the shorter the waiting time.

[0027] S5. The node in the forwarding candidate set in the waiting state determines whether it has received a control packet with the same ID number as the previously received data packet. If so, it abandons the data packet forwarding and returns to the initial listening state to wait for receiving a new packet. If not, it executes step S6. In step S5, the control packet contains the same ID number as the currently forwarded data packet. To ensure that the highest priority node can inhibit the forwarding of the same data packet by the lower priority node after successfully forwarding the data packet, for two nodes within the same hop range , The forwarding time must meet the following requirements:

[0028] in, Indicates the waiting time of high priority nodes, Indicates the waiting time for low priority nodes. Indicates a high priority node The time when the data packet is received, Indicates low priority nodes The time when the data packet is received, Indicates that the control packet comes from arrive The time required for successful reception, that is, the The control package Before receiving In the waiting state.

[0029] S6. The node with the shortest waiting time in the forwarding candidate set is the node with the highest priority. After the waiting time is over, the node with the highest priority updates the sending node position in the data packet to its own node position. The node forwards the data packet along the direction vector of its own position and the position of the surface buoy node. After the node forwards the data packet, it resets the beam direction to the direction from the current node to the previous hop node and sends a control packet. In step S6, each node The simplified expression of the waiting time is:

[0030] in, When the value becomes larger, the waiting time becomes smaller and the end-to-end delay also becomes smaller, but the probability of a node suppressing other low-priority nodes will also decrease, which will lead to relatively higher energy consumption.

[0031] S7, determine whether the surface buoy node has received the ID data packet, if yes, the transmission of the current ID data packet ends; if no, go to step S2 until the data packet is successfully transmitted from the source node to the surface buoy node.

[0032] Embodiment 2: A simulation test was carried out on the open source simulation platform NS3. The nodes were randomly deployed in a three-dimensional spatial network of 5000m*5000m*5000m. The source node was fixed at the seabed coordinate (5000, 5000, 5000), and a surface buoy node was deployed at the sea surface (100, 100, 0). n sensor nodes were randomly deployed in the network, and the number of nodes n increased from 200 to 320 in increments of 20. All nodes are equipped with directional transducers that can transmit data packets in a directionally manner. The beam width of the transducer is set to 60°. Under equal power conditions, the transmission radius of the directional beam is twice that of the omnidirectional mode. The beam angle is controlled by software definition and the beam switching time is negligible. The node omnidirectional transmission range is set to 1000m, and the transmission range of the directional beam is 2000m. The beam model of the node is as follows Figure 2 Half-duplex communication is adopted between nodes; the transmission speed of underwater acoustic is 1500m / s, the data packet size is 2400 bytes, and the modulation rate of underwater acoustic modem is 9600bps.

[0033] Since nodes are randomly distributed, and The sensitivity of is the same. So let . Those skilled in the art will appreciate that the examples described here are intended to help readers understand the principles of the present invention, and it should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. The above embodiments are preferred implementations of the present invention, but the implementations of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention should be equivalent replacement methods and are included in the scope of protection of the present invention.

[0034] Other network simulation parameters are shown in Table 1 below: Table 1. Network simulation parameters

[0035] The simulation results of this embodiment are given below: Among the network performance measurement indicators, the end-to-end average delay, packet delivery rate and average energy consumption formulas are defined as follows:

[0036]

[0037]

[0038] The network performance of the directional transmission-based underwater acoustic opportunity routing protocol as the number of nodes n changes is as follows: Figure 6 , Figure 7 , Figure 8 As shown, they are the average end-to-end delay, data packet delivery rate and average energy consumption, respectively. The DTOR protocol is a hydroacoustic opportunity routing protocol based on directional transmission described in the present invention; the VBF protocol is a vector forwarding routing protocol; and the HHVBF protocol is a hop-by-hop vector forwarding routing protocol.

[0039] from Figure 6 It can be seen that when the number of nodes is 200, 220, 240, 260, 280 and 300, the packet delivery rate of the DTOR protocol is significantly the highest, indicating that the DTOR protocol has a longer transmission distance combined with directional beams under the same power, reducing the impact of packet transmission interruption caused by routing holes in local sparse areas; Figure 7 It can be seen that when the number of nodes is 220, 240, 260, 280, 300, and 320, the average end-to-end delay of the DTOR protocol is significantly the smallest, indicating that the DTOR protocol can reduce the propagation delay through a longer transmission distance of a single hop; Figure 8 It can be seen that when the number of nodes is 220, 240, 260, 280, 300, and 320, the average node energy consumption of the DTOR protocol is slightly higher than that of the VBF protocol, but significantly lower than that of the HHVBF protocol, indicating that DTOR reduces the total number of routing hops and packet redundancy through directional beam and multi-weight routing protocol methods, while improving the successful delivery rate of packets and improving the network energy load balancing. The experimental results show that compared with the traditional routing protocol method based on omnidirectional transmission, the DTOR protocol can effectively improve the performance of the underwater acoustic communication network.

[0040] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for hydroacoustic opportunity routing based on directional transmission, applied to a hydroacoustic sensor network with a multi-hop topology structure, comprising a source node fixed on the bottom of the water, N relay sensor nodes deployed underwater, and a buoy node deployed on the water surface, wherein the source node contains the position information of the surface buoy node, ignoring the position change of the surface buoy node caused by the external environment and each node can obtain and regularly update its own position information through the equipped positioning device, each node is equipped with a multi-mode directional transducer that can realize beam directional forwarding, the beam angle is controlled by software definition and the beam switching time can be ignored, characterized in that, The hydroacoustic opportunity routing method comprises the following steps: S1, initialization stage, each node in the underwater acoustic sensor network obtains its own location information, the source node periodically generates a data packet, and the current node aligns the direction of the directional beam to the position of the surface buoy node to start sending data packets; S2. After the current node sends the data packet, the nodes that successfully receive the data packet within the transmission range of the current node's directional beam form the forwarding candidate set of the current node. After receiving the data packet, the nodes in the forwarding candidate set extract the packet ID number and the location information of the current node and the surface buoy node; S3, the nodes in the forwarding candidate set determine whether the data packet has been forwarded. If so, the data packet is discarded and forwarding is abandoned; if not, step S4 is executed; S4. The nodes in the forwarding candidate set calculate their respective priority weight factors according to their respective location information and current remaining energy. The larger the priority weight factor, the higher the forwarding priority and the shorter the waiting forwarding time of the node. The nodes in the forwarding candidate set calculate and set the waiting forwarding time according to their respective priority weight factors and enter the waiting holding state, while monitoring the channel. S5. The node in the forwarding candidate set in the waiting state determines whether it has received a control packet with the same ID number as the previously received data packet. If so, it abandons the data packet forwarding and returns to the initial listening state to wait for receiving a new packet. If not, it executes step S6. S6. The node with the shortest waiting time in the forwarding candidate set is the node with the highest forwarding priority. After the waiting time ends, the node with the highest forwarding priority updates the sending node position in the data packet to its own node position. The node forwards the data packet along the direction vector of its own position and the position of the surface buoy node. After the node forwards the data packet, it resets the beam direction to the direction from the current node to the previous hop node and sends a control packet. S7. Determine whether the surface buoy node has received the data packet with the ID number. If so, the transmission of the current data packet with the ID number is completed; if not, go to step S2 until the data packet is successfully transmitted from the source node to the surface buoy node.

2. The method for hydroacoustic opportunity routing based on directional transmission according to claim 1, characterized in that: In step S1, the model of the directional beam is abstracted as a fan. In addition to the data information collected by the active node, the data packet also includes the data packet type and ID number, the sending node ID number and coordinate information, and the surface buoy node coordinate information.

3. The method for hydroacoustic routing based on directional transmission according to claim 1, characterized in that: In step S4, the nodes in the forwarding candidate set are forwarded The priority of the node is based on the depth difference of the node. , the distance difference from the node to the direction vector and the remaining energy of the node, using the priority weight factor Measuring Nodes The forwarding priority of The larger the value, the higher the forwarding priority of the node. The value is calculated as follows: in, It represents the ratio coefficient of depth difference to distance difference, which is adjusted according to the specific deployment of network nodes. and The sensitivity is dynamically adjusted. Indicates the nodes within the beam range The depth difference between the forwarding nodes, represents the transmission radius of the node, Indicates the nodes within the beam range The distance difference to the direction vector, Representation Node The current remaining energy, represents the initial set energy of the node, The bigger, The smaller, The larger the The larger the value, the higher the priority of the node in the candidate node set.

4. The method for hydroacoustic routing based on directional transmission according to claim 3 is characterized in that: In step S4, the waiting forwarding time of each candidate node Inversely proportional to the priority weight factor: in The maximum holding time is set, and the node with higher forwarding priority has shorter waiting time.

5. The method for hydroacoustic opportunity routing based on directional transmission according to claim 1, characterized in that: In step S5, the control packet and the currently forwarded data packet have the same ID number.

6. The method for hydroacoustic routing based on directional transmission according to claim 1, characterized in that: In step S5, in order to ensure that the highest priority node can inhibit the forwarding of the same data packet by the lower priority node after successfully forwarding the data packet, two nodes within the same hop range are , The forwarding time must meet the following requirements: in, Indicates the waiting time of high priority nodes, Indicates the waiting time of low priority nodes, Indicates a high priority node The time when the data packet is received, Indicates low priority nodes The time when the data packet is received, Indicates that the control packet is from a high priority node Reaching a low priority node The time required for successful reception, that is, the low priority node needs to be guaranteed The control packet is received by the low priority node Receive the low priority node before In the waiting state.

7. The method for hydroacoustic opportunity routing based on directional transmission according to claim 1, characterized in that: In step S6, each node The simplified expression of the waiting time is: in, represents the priority weight factor, represents the transmission radius of the node, represents the speed of sound propagation in water, When the value becomes larger, the waiting time becomes smaller and the end-to-end delay also becomes smaller, but the probability of a node suppressing other low-priority nodes will also decrease, which will lead to relatively higher energy consumption.

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