An underwater acoustic opportunistic routing method based on directional transmission

Abstract

The application discloses a kind of underwater acoustic opportunistic routing protocol methods based on directional transmission.The conventional underwater acoustic opportunistic routing protocol adopts omnidirectional transmission mode, there is high problem of data packet redundancy rate, and in local sparse area, it is easy to appear " detour " and routing hole phenomenon, lead to network throughput drop and energy consumption increase.Based on the above-mentioned defects, the application introduces the beam forming technology of directional transducer, so that the sending node can be oriented to the target node for data forwarding, improve network space multiplexing rate.Combined with the advantage that directional transducer transmits farther under the same transmission power, reduce the probability of occurrence of routing hole and reduce the transmission delay of network.Considering the depth information, position information and residual energy of node, the average life of network is improved.Compared with the conventional omnidirectional transmission-based routing protocol method, the method greatly improves the performance of underwater acoustic communication network.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of underwater acoustic communication, and particularly relates to an underwater acoustic opportunistic routing method based on directional transmission. BACKGROUND

[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 research hotspot in recent years. The traditional underwater sensor network mainly consists of a ground base station, a water surface buoy node and an underwater sensor node, and the underwater data transmission link is generally from a source node on the water bottom to a sensor node and then to a water surface buoy node. Due to the diversity and complexity of the underwater environment, underwater acoustic communication has the characteristics of serious noise, limited energy and long transmission delay compared with radio communication. Therefore, the key technical problem of current underwater acoustic communication is how to effectively and reliably forward data to the water surface buoy node. The routing protocol plays a key role in this process and determines whether the data packet can be transmitted to the destination node through an efficient and reliable path.

[0003] The existing underwater acoustic routing protocol has made improvements on how to improve the performance bottlenecks such as routing hole, limited energy and long transmission delay, but few studies focus on improving performance by combining directional transducers. The directional transducer can concentrate energy in a small angle. Under the condition of equal power, the directional transducer can transmit a longer distance with a smaller beam width than the omnidirectional transmission mode, thereby increasing the spatial reuse rate and reducing the end-to-end delay and energy loss, thereby greatly improving the communication efficiency of the underwater acoustic network. SUMMARY

[0004] The main purpose of the present application is to overcome the shortcomings and deficiencies of the prior art, and to provide an underwater acoustic opportunistic routing method based on directional transmission.

[0005] In order to achieve the above purpose, the following technical scheme is adopted in the present application:

[0006] An underwater acoustic opportunistic routing method based on directional transmission is applied to a multi-hop topology underwater acoustic sensor network, which includes one source node fixed on the water bottom, N relay sensor nodes deployed underwater, and one buoy node deployed on the water surface. The source node contains the position information of the water surface buoy node, and each node can obtain and regularly update its own position information through the equipped positioning device, ignoring the position changes of all nodes caused by external environment. Each node is equipped with a multi-modal directional transducer that can realize beam directional forwarding, and the beam angle is controlled by software definition and the switching time of the beam can be ignored. The underwater acoustic opportunistic routing method comprises the following steps:

[0007] S1, initialization phase, each node in the underwater acoustic sensor network acquires its own position 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 the data packet;

[0008] S2, after the current node sends the data packet, the nodes that successfully receive the data packet within the current node directional beam transmission range form a forwarding candidate set of the current node. The nodes in the forwarding candidate set extract the ID number of the packet and the position information of the current node and the surface buoy node after receiving the data packet;

[0009] S3, the nodes in the forwarding candidate set determine whether to forward the data packet, if yes, discard the data packet and give up forwarding; if not, execute step S4;

[0010] S4, the nodes in the forwarding candidate set calculate their priority weight factors according to their own position information and the 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 own priority weight factors to enter the waiting and keeping state, and listen to the channel at the same time;

[0011] S5, the nodes in the forwarding candidate set in the waiting and keeping state determine whether they have received a control packet with the same ID number as the previously received data packet, if yes, give up data packet forwarding and return to the initial listening state to wait for receiving a new packet; if not, execute step S6;

[0012] S6, the node with the shortest waiting time in the forwarding candidate set, i.e. the node with the highest priority, updates the sending node position in the data packet to its own node position after the waiting time ends. 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, the beam direction is reset to the direction from the current node to the previous hop node to send the control packet;

[0013] S7, determine whether the surface buoy node receives the ID data packet, if yes, the transmission of the current ID number 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.

[0014] Further, in step S1, the model of the directional beam is abstracted as a sector. Under the condition of equal power, the transmission distance of the directional beam is farther than that of the omnidirectional beam. The data packet carries data information collected by the source node, data packet type and ID number, sending node ID and coordinate information, and surface buoy node coordinate information.

[0015] The directional transmission mechanism is used because it concentrates the transmission power at a certain angle to transmit over a longer distance, thereby increasing spatial reuse and reducing end-to-end latency. However, multimode directional transducers achieve beam-oriented forwarding through weighted summation of multiple modes, and the beam's directivity and power are controlled by internal software. This control logic is complex, and the beam shape is not entirely regular. This invention only needs to change the beam angle without altering the beamwidth; therefore, it abstracts the beam model into a regular sector shape, which is beneficial for selecting candidate nodes.

[0016] Furthermore, in step S4, nodes within the forwarding candidate set are... The priority takes into account the depth difference of the nodes. Distance difference from node to direction vector and the remaining energy of the nodes This invention uses a priority weighting factor. Measure node Forwarding priority. The higher the value, the higher the forwarding priority of the node. The value is calculated as follows:

[0017]

[0018] in, The ratio of depth difference to distance difference can be adjusted based on the specific deployment of network nodes. and The sensitivity is dynamically adjusted. Indicates nodes within the forwarding candidate set The depth difference between the current node and the current node. Indicates the transmission radius of the node. Indicates nodes within the forwarding candidate set The distance difference to the direction vector. This represents the current remaining energy of the node. This represents the initial energy setting of the node. The larger, The smaller, The larger, the better The larger the value, the higher the priority of the node in the candidate node set.

[0019] The priority weighting factor for nodes is calculated by comprehensively considering the node depth information, location information, and remaining energy within the forwarding candidate set. This is because selecting nodes with larger depth differences and closer distances to the direction vector as next-hop forwarding nodes ensures that these nodes are closer to the surface buoy node, resulting in fewer total hops for data packets to reach the surface buoy node. Nodes with more remaining energy should have more opportunities to participate in data packet forwarding, preventing transmission interruption due to rapid energy depletion caused by frequent forwarding by some nodes.

[0020] Furthermore, in step S4, the waiting time for forwarding of nodes within the forwarding candidate set is... Inversely proportional to the priority weight factor:

[0021]

[0022] The maximum hold time is set, and nodes with higher priority have shorter wait times. This is because it ensures that once the node with the highest priority factor ends its wait time and begins forwarding, other nodes in the forwarding candidate set remain in a wait-and-hold state.

[0023] Among them, the waiting time for forwarding The reason it is inversely proportional to priority is that it ensures that the node closer to the surface buoy node and with more remaining energy will forward the data packet earlier.

[0024] Furthermore, in step S5, the control packet contains the same ID number as the currently forwarded data packet. To ensure the suppression function of the highest priority node forwarding the same data packet to other lower priority nodes after successfully forwarding it, for two nodes within the same hop range... , Forwarding time must meet the following requirements:

[0025]

[0026] in, This indicates the waiting time for high-priority nodes. This indicates the waiting time for low-priority nodes. Indicates a high-priority node The moment of receiving data packets, Indicates low-priority nodes The moment of receiving data packets, This indicates that the control packet originates from the high-priority node. Reaching low priority nodes And the time required for successful reception, i.e., ensuring low-priority nodes Control packets are sent to low-priority nodes Receive low-priority nodes It is in a waiting state.

[0027] Further, in step S6, each node The expression of the waiting time is simplified and arranged as follows:

[0028] Each node The expression of the waiting time is simplified and arranged as follows:

[0029]

[0030] Wherein, The priority weight factor is represented by p, The transmission radius of the node is represented by r, The sound propagation speed is represented by c, When the value of the value is larger, the waiting time is smaller, and the end-to-end delay is also smaller, but the probability of the node suppressing other low-priority nodes is also reduced, thereby causing relatively higher energy consumption.

[0031] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0032] (1) In view of the problems of high data packet redundancy in omnidirectional transmission and the problems of "detour" and routing hole easily occurring in local sparse areas, the present application can limit the forwarding area in the fan-shaped area towards the water surface buoy node by using the underwater acoustic opportunistic routing protocol method designed in combination with the directional transmission mechanism, so that the nodes outside the fan-shaped area will not participate in the forwarding of the data packet, thereby reducing the redundancy of the data packet in the transmission process. At the same time, the transmission distance is farther under the same power, so that the network performance in the local sparse area is better;

[0033] (2) The present application considers the node depth, position information and node residual energy consumption when selecting the forwarding node. Through multi-factor joint optimization, the energy load balancing of the network is improved, the network service life is prolonged, and the application scenario of high delay, low bandwidth and node energy limited of the underwater acoustic sensor network is suitable. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0035] Figure 1 is a flow chart of the underwater acoustic opportunistic routing method based on directional transmission disclosed by the present application;

[0036] Figure 2is a beam model diagram of a kind of underwater acoustic opportunistic routing method based on directional transmission disclosed by the application;

[0037] Figure 3 is a node in a kind of underwater acoustic opportunistic routing method based on directional transmission disclosed by the application and schematic diagram;

[0038] Figure 4 is a frame structure diagram of data packet and control packet in a kind of underwater acoustic opportunistic routing method based on directional transmission disclosed by the application;

[0039] Figure 5 is a routing process schematic diagram of node in the underwater acoustic opportunistic routing method based on directional transmission in the embodiment of the application;

[0040] Figure 6 is a data packet delivery rate performance result diagram of the underwater acoustic opportunistic routing method based on directional transmission in the embodiment of the application using NS-3 discrete network simulator for simulation;

[0041] Figure 7 is an average end-to-end delay performance result diagram of the underwater acoustic opportunistic routing method based on directional transmission in the embodiment of the application using NS-3 discrete network simulator for simulation;

[0042] Figure 8 is a node average energy consumption result diagram of the underwater acoustic opportunistic routing method based on directional transmission in the embodiment of the application using NS-3 discrete network simulator for simulation. DETAILED DESCRIPTION

[0043] In order to make the person skilled in the art better understand the present application scheme, the technical scheme in the embodiments of the present application will be described clearly and completely 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, not all. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor are within the scope of protection of the present application.

[0044] In the present application, it is referred to "embodiment" that the specific features, structures or characteristics described in conjunction with the embodiment can be contained in at least one embodiment of the present application. The phrase appears in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment to other embodiments. The person skilled in the art explicitly and implicitly understands that the embodiments described in the present application can be combined with other embodiments.

[0045] Embodiment 1:

[0046] As Figure 1As shown, when the source node has a data packet to be forwarded to the water surface buoy node, the underwater acoustic opportunistic routing protocol based on directional transmission forwarding method disclosed by the application is used, and the forwarding method comprises the following steps:

[0047] S1, in the initialization stage, each node in the underwater acoustic sensor network acquires its own position information, the source node periodically generates a data packet, and the current node starts to send the data packet by aligning the direction of the directional beam to the position of the water surface buoy node;

[0048] In step S1, the model of the directional beam is abstracted as a sector. Under the condition of equal power, the transmission distance of the directional beam is farther than that of the omnidirectional beam. The data packet carries the data information collected by the source node, and also includes the data packet type and ID number, the sending node ID and coordinate information, and the water surface buoy node coordinate information.

[0049] S2, after the current node sends the data packet, the nodes successfully receiving the data packet within the current node directional beam sending range form a forwarding candidate set of the current node. The nodes in the forwarding candidate set extract the ID number of the data packet and the position information of the current node and the water surface buoy node after receiving the data packet;

[0050] S3, the nodes in the forwarding candidate set judge whether the data packet has been forwarded, if yes, the data packet is discarded and the forwarding is abandoned; if not, step S4 is executed;

[0051] S4, the nodes in the forwarding candidate set calculate their own priority weight factors according to their own position information and the current residual energy. The greater the priority weight factor is, the higher the forwarding priority is, and the shorter the waiting forwarding time of the node is. The nodes in the forwarding candidate set calculate and set the waiting forwarding time according to their own priority weight factors to enter the waiting state, and listen to the channel at the same time;

[0052] In step S4, the nodes in the forwarding candidate set The priority of the node is comprehensively considered from the depth difference , the distance difference of the node to the direction vector , and the residual energy of the node. The priority weight factor is used to measure the forwarding priority of the node in the application. The greater the value is, the higher the forwarding priority of the node is. The value is calculated as follows:

[0053]

[0054] wherein, represents the proportional coefficient of the depth difference and the distance difference, and can be calculated according to the specific deployment of the network node and The sensitivity is dynamically adjusted. Represents nodes within the beam range The depth difference between the forwarding node and the forwarding node. Indicates the transmission radius of the node. Represents nodes within the beam range The distance difference to the direction vector. This represents the current remaining energy of the node. This represents the initial energy setting of the node. The larger, The smaller, The larger, the better The larger the value, the higher the priority of the node in the candidate node set. The waiting time for forwarding of each candidate node. Inversely proportional to the priority weight factor:

[0055]

[0056] The maximum hold time is set, and nodes with higher priority have shorter wait times.

[0057] S5. Nodes in the forwarding candidate set in the waiting state determine whether they have received a control packet with the same ID number as the previously received data packet. If so, they abandon data packet forwarding, return to the initial listening state, and wait to receive new packets. If not, they proceed to step S6.

[0058] In step S5, the control packet contains the same ID number as the currently forwarded data packet. To ensure the highest priority node can suppress the forwarding of the same data packet by a lower priority node after successfully forwarding it, for two nodes within the same hop range... , Forwarding time must meet the following requirements:

[0059]

[0060] in, This indicates the waiting time for high-priority nodes. This indicates the waiting time for low-priority nodes. Indicates a high-priority node The moment of receiving data packets, Indicates low-priority nodes The moment of receiving data packets, Indicates control packet from arrive And the time required for successful reception, i.e., it needs to be guaranteed. The control packet was Before receiving It is in a waiting state.

[0061] S6, the node with the shortest waiting time in the forwarding candidate set is the highest priority node, after the waiting time ends, the highest priority node updates the sending node position in the data packet to its own node position, and the node forwards the data packet along the direction vector from its own position to the water surface buoy node position, after the node forwards the data packet, the beam direction is reset to the direction from the current node to the previous hop node to send the control packet;

[0062] In step S6, each node The expression obtained by simplifying and arranging the waiting time is:

[0063]

[0064] wherein, When the value of the value increases, the waiting time becomes smaller, and the end-to-end delay also becomes smaller, but the probability of the node suppressing other low-priority nodes also decreases, thereby causing relatively higher energy consumption.

[0065] S7, judging whether the water surface buoy node receives the ID data packet, if yes, the transmission of the current ID number data packet ends; if no, going to step S2. Until the data packet is successfully transmitted from the source node to the water surface buoy node.

[0066] Embodiment 2:

[0067] Simulation tests are performed on the open source simulation platform NS3, the nodes are randomly deployed in a three-dimensional space network of 5000m*5000m*5000m, the source node is fixed at the position of the seabed coordinate (5000, 5000, 5000), a water surface buoy node is deployed at the sea surface (100, 100, 0), n sensor nodes are randomly deployed in the network, the number of nodes n increases from 200 to 320 with an increment of 20. All nodes are equipped with a directional transducer that can transmit data packets in a directional manner, the beam width of the transducer is set to 60°. Under the condition of equal power, the transmission radius of the directional beam is twice that of the omnidirectional mode. The beam angle is controlled by software definition and the switching time of the beam can be ignored. The omnidirectional transmission range of the node is set to 1000m, and the transmission range of the directional beam is 2000m. The beam model of the node is shown in Figure 2 The nodes use half-duplex communication; the transmission speed of underwater sound is 1500m / s, the data packet size is 2400 bytes, and the modulation rate of the underwater acoustic modem is 9600bps.

[0068] Due to the random distribution of the nodes, the sensitivity of the nodes to and is the same. Therefore, Those skilled in the art will appreciate that the examples described herein are intended to facilitate understanding of the principles of the application and should be understood as not limiting the scope of the application to such specifically recited examples and embodiments. The above-described embodiments are preferred embodiments of the application, but the embodiments of the application are not limited to the above-described embodiments, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the application should be equivalent replacement methods, and are included in the protection scope of the application.

[0069] Other network simulation parameters are shown in Table 1 as follows:

[0070] Table 1. Network simulation parameter table

[0071]

[0072] The simulation results of the present embodiment will be given as follows:

[0073] In the network performance measurement indicators, the average end-to-end delay, packet delivery rate and average energy consumption formula are defined as follows:

[0074]

[0075]

[0076]

[0077] The network performance of the directional transmission-based underwater acoustic opportunistic routing protocol with the number of nodes n is shown in Figure 6 、 Figure 7 、 Figure 8 , respectively, the average end-to-end delay, packet delivery rate and average energy consumption. Among them, the DTOR protocol is the directional transmission-based underwater acoustic opportunistic routing protocol described in the application; the VBF protocol is the vector forwarding routing protocol; the HHVBF protocol is the hop-by-hop vector forwarding routing protocol.

[0078] It can be seen from Figure 6 that when the number of nodes is 200, 220, 240, 260, 280 and 300, the packet delivery rate of the DTOR protocol is obviously the highest, which shows that the DTOR protocol has a longer transmission distance under the same power combined with directional beams, reducing the influence of the existence of routing holes in the local sparse area on the interruption of data packet transmission; from Figure 7 It can be seen that when the number of nodes is 220, 240, 260, 280, 300, 320, the average end-to-end delay of the DTOR protocol is obviously the smallest, which shows that the DTOR protocol can reduce the propagation delay through the longer transmission distance of single hop; from Figure 8It can be seen that when the number of nodes is 220, 240, 260, 280, 300 and 320, the average energy consumption of the nodes of the DTOR protocol is slightly higher than that of the VBF protocol, but is obviously lower than that of the HHVBF protocol, which indicates that the DTOR reduces the total hop count and the redundancy of data packets through the directional beam and the multi-weight routing protocol method, improves the data packet success delivery rate, and improves the network energy load balancing. The experimental results show that, compared with the traditional omnidirectional transmission-based routing protocol method, the DTOR protocol can effectively improve the performance of the underwater acoustic communication network.

[0079] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, which are all included in the protection scope of the present application.

Claims

1. A method of underwater acoustic opportunistic routing based on directional transmission, applied to an underwater acoustic sensor network with a multi-hop topology, comprising one source node fixed on the sea floor, N relay sensor nodes deployed underwater, and one buoy node deployed on the water surface, wherein the source node contains the location information of the water surface buoy node, the location change of the water surface buoy node caused by external environment is ignored, and each node can obtain and regularly update its own location information through the equipped positioning device, 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 switching time of the beam can be ignored. The underwater acoustic opportunistic routing method comprises the following steps: S1, an initialization stage, each node in the underwater acoustic sensor network acquires its own position 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 the data packet; S2, after the current node sends the data packet, nodes that successfully receive the data packet in the current node directional beam sending range form a forwarding candidate set of the current node, and the nodes in the forwarding candidate set extract the ID number of the packet and the position information of the current node and the surface buoy node after receiving the data packet; S3, the nodes in the forwarding candidate set determine whether the data packet has been forwarded, if yes, the data packet is discarded and the forwarding is abandoned; if not, step S4 is performed; S4. Nodes in the forwarding candidate set calculate their respective priority weight factors based on their location information and current remaining energy. The larger the priority weight factor, the higher the forwarding priority and the shorter the waiting time for forwarding. Nodes in the forwarding candidate set calculate and set their waiting time based on their respective priority weight factors, enter a waiting state, and simultaneously listen to the channel. In step S4, nodes in the forwarding candidate set... Priority is determined by considering the depth difference of the nodes. Distance difference from node to direction vector And the remaining energy of the nodes, using priority weighting factors. Measure node Forwarding priority The larger the value, the higher the node's forwarding priority. The value is calculated as follows: in, The ratio of depth difference to distance difference is a coefficient that varies depending on the specific deployment of network nodes. and The sensitivity is dynamically adjusted. Represents nodes within the beam range The depth difference between the forwarding node and the forwarding node. Indicates the transmission radius of the node. Represents nodes within the beam range The distance difference to the direction vector, Represents a node The current remaining energy, This represents the initial energy setting of the node. The larger, The smaller, The larger, the better The larger the value, the higher the priority of the node in the candidate node set; S5, the nodes in the forwarding candidate set in the waiting state determine whether a control packet with the same ID number as the previously received data packet is received, if yes, the data packet forwarding is abandoned, and the initial listening state is returned to wait for receiving a new packet; if not, step S6 is performed; S6, the node with the shortest waiting time in the forwarding candidate set, i.e., the node with the highest forwarding priority, updates the sending node position in the data packet to the node position of the node after the waiting time ends, the node forwards the data packet along the direction vector of the node position and the surface buoy node position, and the node re-sets the beam direction to the direction from the current node to the previous hop node to send the control packet; S7, it is determined whether the surface buoy node receives the data packet with the ID number, if yes, the transmission of the data packet with the current ID number is ended; if not, step S2 is performed; Until the data packet is successfully transmitted from the source node to the surface buoy node.

2. The underwater acoustic opportunistic routing method based on directional transmission according to claim 1, characterized in that, In step S1, the model of the directional beam is abstracted as a sector, and the data packet includes data packet type and ID number, sending node ID number and coordinate information, and surface buoy node coordinate information in addition to carrying data information collected by the source node. 3.The underwater acoustic opportunistic routing method based on directional transmission of claim 1, wherein, The waiting forwarding time of each candidate node in the step S4 Inversely proportional to the priority weight factor: wherein is the set maximum hold time, the higher the forwarding priority, the shorter the waiting time for the node.

4. The underwater acoustic opportunistic routing method based on directional transmission according to claim 1, characterized in that, In step S5, the control packet has the same ID number as the currently forwarded data packet.

5. The underwater acoustic opportunistic routing method based on directional transmission according to claim 1, characterized in that, In step S5, to ensure the suppression function of the highest priority node forwarding the same data packet to a lower priority node after successfully forwarding the data packet, for two nodes within the same hop range... , Forwarding time must meet the following requirements: wherein, represents the waiting time of a high priority node, represents the waiting time of a low priority node, represents a high priority node the time at which a data packet is received, represents a low priority node the time at which a data packet is received, represents the time required for a control packet to travel from a high priority node to a low priority node and be successfully received, i.e. to guarantee that the control packet of a low priority node is received by a low priority node before the low priority node is in a waiting hold state.

6. The underwater acoustic opportunistic routing method based on directional transmission according to claim 1, wherein, In the step S6, each node The expression obtained by simplifying the waiting time is as follows: wherein, represents a priority weight factor, represents a transmission radius of a node, represents a sound speed in water, When the value of the priority weight factor increases, the waiting time decreases, and the end-to-end delay also decreases, but the probability of the node suppressing other low-priority nodes also decreases, thereby causing relatively higher energy consumption.

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