CN104348562B - Multiple access method based on UW-CSMA/CA in the communication of a kind of underwater acoustic network - Google Patents

Abstract

The invention relates to a UW-CSMA/CA-based multiple access method in underwater acoustic network communication, comprising: when a node is in the WFCTS state, if the node receives the RTS of the destination node, it enters the back-off state and competes for the channel again, If the node receives the RTS from other nodes, it will reply CTS and enter the WFDTA state. If it receives the RTS that is not sent to the node, it will discard and wait for the corresponding CTS. If the node listens to any xCTS and xDATA, it will enter the silent state; When the node is in the WFDATA state, if the node receives the RTS from the source node, it will reply to the CTS and reset the timeout period of the WFDATA state. If the node receives the xRTS and xCTS sent by the source node to other nodes, it will immediately stop waiting for DATA and enter In the QUIET state, if the node listens to any xDATA, it will enter the silent state, otherwise, it will wait for the corresponding DATA until it times out.

Description

A Multiple Access Method Based on UW-CSMA/CA in Underwater Acoustic Network Communication

technical field

The invention relates to the field of underwater acoustic network communication, in particular to a UW-CSMA/CA-based multiple access method in underwater acoustic network communication.

Background technique

The ocean occupies more than two-thirds of the earth's area, and the observation and development of the ocean have attracted more and more attention from all countries. At the same time, the underwater acoustic network has become a research hotspot worldwide. The data link layer protocol is an important part of the study of underwater acoustic network. Compared with the wireless channel, the bandwidth of the underwater acoustic channel is limited and the propagation delay is large, which poses a great challenge to the design of the MAC protocol of the underwater acoustic network.

According to the channel acquisition method of the protocol, the MAC protocol is divided into a scheduling-based MAC protocol and a contention-based MAC protocol. Due to the narrow available frequency band of the underwater acoustic channel, it is difficult to use the scheduling-based FDMA. Scheduling-based TDMA requires accurate synchronization of clocks and guard intervals of each node, which is very difficult in underwater acoustic networks with high propagation delay and random space-time frequency variation. Scheduling-based CDMA is rarely used because of its high computational complexity. Therefore, contention-based MAC protocols are more suitable for underwater acoustic networks. Competition-based MAC protocols can be further divided into ALOHA-based MAC protocols and handshake-based MAC protocols. This application mainly studies the MAC protocol based on handshake in the multi-diving underwater acoustic network.

The handshake-based MAC protocol uses RTS/CTS handshake to reserve channels to solve the problem of hidden terminals and exposed terminals. Disclosed in reference 1 "Affan A. Syed, Wei Ye, Jobn Heidemann. T-Lohi: A New Class of MAC Protocols For Underwater Acoustic Sensor Networks [C]. The27th Conference on Computer Communications, Phoenix, 2008: 231-235" In the T-Lohi protocol, short wake-up signals are used to reserve channels to prevent data packet collisions. For distributed, short-distance, and dense networks, T-Lohi can provide network services with stable throughput and high energy utilization. In reference 2 "X.Guo, M.R.Frater, and M.J.Ryan.Design of a Propagation-Delay-Tolerant MAC Protocol for UnderwaterAcoustic Sensor Networks[J].Oceanic Engineering,2009,34(2):170-180" In this paper, the influence of high propagation delay of underwater acoustic channel is reduced by specifying the reply time of CTS, so as to improve the throughput of the network. In reference 3 "Nitthita Chirdchoo, Wee-Seng Soh, and Kee Chaing Chua. RIPT: A Receiver-initiated Reservation-based Protocol for Underwater Acoustic Networks [J]. Selected Areas in Communications, 2008,26(9):1744- 1753" proposed a random access MAC protocol that initializes the communication process through the receiving end, so that all its neighboring nodes send the data packets to be sent to the receiving end in the form of data packet queues. In reference 4 "Dong Fang, Yu Li, Haining Huang, Li Yin. A CSMA/CA-based MAC Protocol for Underwater Acoustic Networks [C]. 6th International Conference on Wireless Communications, Networking and Mobile Computing, Chengdu, 2010: 1- In 4", a MAC protocol suitable for underwater acoustic networks is designed, and it is named UW-CSMA/CA protocol. The multiple access method based on this protocol adopts the strategy of persistent waiting to reduce the number of back-offs, thereby improving the throughput of the network. quantity.

In the UW-CSMA/CA protocol, the durations of RTS, CTS, DATA, and ACK are respectively marked as T _RTS , T _CTS , T _DATA , and T _ACK , and the maximum propagation delay is marked as τ _max . Based on the UW-CSMA/CA protocol, the nodes in the underwater acoustic network may be in six states: IDLE, CTD, WFCTS, WFDATA, WFACK, and QUIET.

Referring to Figure 1, in the UW-CSMA/CA protocol, the basic communication process between the nodes in the underwater acoustic network is as follows: when the source node S has data packets to send, the node state changes from IDLE to CTD, and when the CTD state ends , the source node S will send RTS and turn to the WFCTS state, set the timeout period to 2τ _max +T _CTS ; after receiving the RTS, the destination node D will immediately send a CTS and turn to the WFDATA state, and set the timeout period to 2τ _max +T _DATA ; After receiving the CTS, the source node S immediately sends DATA and enters the WFACK state, and sets the timeout period to 2τ _max + T _ACK ; after the destination node D receives the DATA, it immediately sends an ACK and ends the communication (curved arrow in Figure 1 Indicates that the node ends this handshake communication); the source node S ends this communication after receiving the ACK.

The above is the description of the basic communication process between nodes in the underwater acoustic network. In practical applications, due to the complexity of the underwater acoustic network environment, nodes need to deal with various possible situations. In the multiple access method, how nodes deal with various possible situations is described. The UW- The multiple access method in the CSMA/CA protocol is described accordingly.

Let node X be any node in the underwater acoustic network.

Step 1), node X is in sleep state or waiting state, if the node receives an acoustic wake-up signal, go to step 2); if the backoff timeout and it has data to send, go to step 8); if the silence timeout and there is If the backoff is paused, it will continue to backoff, and continue to be in the sleeping or waiting state; if the silence times out and there is no paused backoff, it will continue to be in the sleeping or waiting state; if it has data to send and is not in the backing off or silent state, then After setting the backoff timer, it will continue to be in the sleeping state or waiting state. If it has data to send and is in the backoff or silent state, it will continue to be in the sleeping state or waiting state.

Step 2), node X wakes up and enters the state of receiving network control frames.

Step 3), if the receiving timeout, go to step 1), if the receiving verification is wrong, go to step 1); if the network control frame is received, check the destination address of the network control frame, if the destination address is not node X , then enter the silent state, and then go to step 1), if the destination address is node X and is not silent, then go to step 4), if the destination address is node X and is silent, then go to step 1).

Step 4), judge the type of the received network control frame, if the control frame type is RTS, go to step 5), if it is other types, go to step 1);

Step 5), node X replies CTS to the source node, and then sets the timeout timer T _WFDATA =2×τ _max +T _DATA , where τ _max is the maximum propagation delay, and T _DATA is the duration of DATA.

Step 6), node X waits for DATA, if DATA is received before timeout, go to step 7), otherwise go to step 1).

Step 7), turn off the timeout timer, and then verify the received DATA, if the verification is correct, pass the DATA to the network layer, if not, discard the DATA; then reply ACK according to the verification result, and finally re-execute step 1 ).

Step 8), node X sends RTS, and sets a timeout timer T _WFCTS =2×τ _max +T _CTS , where τ _max is the maximum propagation delay, and T _CTS is the duration of CTS.

Step 9), node X waits for the CTS of the destination node, if the network control frame is correctly received before the timeout, then go to step 10), if the verification error or timeout, turn off the timeout timer, add 1 to the number of backoffs, and then turn to to step 1).

Step 10), node X judges the type of the received network control frame, if the received network control frame is a CTS to be transmitted to node X, then close the timeout timer and go to step 0; if the received network control frame is to be transmitted For the CTS or DATA of other nodes, turn off the timeout timer, add 1 to the number of backoffs, set the silent timer, and go to step 1) 0; if the received network control frame type is RTS, discard the RTS, and then go to Step 9).

Step 11), node X sends DATA, and then sets the timeout timer T _WFACK =2×τ _max +T _ACK , where τ _max is the maximum propagation delay, and T _ACK is the duration of ACK.

Step 12), node X waits for the ACK of the destination node, if the network control frame is received before the timeout, and the received network control frame is verified correctly, go to step 13), if the received network control frame is verified incorrectly, then Continue to wait for the ACK of the destination node; if it times out, add 1 to the number of backoffs, and then go to step 1).

Step 13), node X judges the type of the received network control frame, if the received network control frame is an ACK for node X, turn off the timeout timer, and then go to step 12), otherwise go to step 12).

Step 14), Node X judges the parity bit in the ACK. If the verification is correct, the number of backoffs is cleared, and then go to step 1), otherwise, the number of backoffs is increased by 1, and then go to step 1).

The above is a description of the steps of the multiple access method in the existing UW-CSMA/CA protocol. As can be seen from the above description, this method adopts the idea of persistent waiting, for example: in step 6), the node persists in waiting for the corresponding CTS, and discards any RTS until it receives a CTS or times out; in step 12) and step 13 ), the node persists in waiting for the corresponding ACK; any other frames are discarded until an ACK is received or a timeout occurs. But in some states, according to the type of the monitored frame, it can be judged that the node will not wait for the expected frame. If it continues to wait, it will waste time, which is not conducive to improving the throughput of the protocol in the underwater acoustic environment.

Contents of the invention

The purpose of the present invention is to reduce the time wasted by the nodes in the existing UW-CSMA/CA protocol by insisting on waiting, and improve the throughput of the UW-CSMA/CA protocol in the underwater acoustic environment.

In order to achieve the above object, the present invention provides a UW-CSMA/CA-based multiple access method in underwater acoustic network communication, including:

Step 1), node X is in sleep state or waiting state; if the node receives an acoustic wake-up signal, go to step 2); if the backoff timeout and it has data to send, go to step 8); if the silence timeout and there is If the backoff is paused, it will continue to backoff and continue to be in the sleeping or waiting state; if the silence times out and there is no paused backoff, it will continue to be in the sleeping or waiting state; if it has data to send and is not in the backing off or silent state, set Set the backoff timer, and then continue to sleep or wait. If it has data to send and is in the backoff or silent state, it will continue to sleep or wait;

Step 2), node X wakes up, and enters the state of receiving network control frames;

Step 3), if the receiving timeout, go to step 1), if the receiving verification is wrong, go to step 1); if a network control frame is received, check the destination address of the received network control frame, if the destination address is not Node X, then enter the quiet state, and then go to step 1), if the destination address is node X and is not quiet, then go to step 4), if the destination address is node X and is quiet, then go to step 1);

Step 4), judge the type of the received network control frame, if the control frame type is RTS, go to step 5), if it is other types, go to step 1);

Step 5), node X replies CTS to the source node, and then sets the timeout timer T _WFDATA =2×τ _max +T _DATA , where τ _max is the maximum propagation delay, and T _DATA is the duration of DATA;

Step 6), node X waits for DATA, if it receives DATA before the timeout, then go to step 7), if the node receives the RTS sent by the source node to the node, then go to step 5); if the node receives the source node When sending xRTS or xCTS to other nodes, immediately end waiting for DATA, and enter the silent state, set the silent timer, go to step 1); if the node listens to any xDATA, enter the silent state, set the silent timer, go to step 1), else go to step 1);

Step 7), turn off the timeout timer, and then verify the received DATA, if the verification is correct, pass the DATA to the network layer, if it is incorrect, discard the DATA; then reply ACK according to the verification result, and finally go to the step again 1);

Step 8), node X sends RTS, and sets the timeout timer T _WFCTS =2×τ _max +T _CTS , where T _CTS is the duration of CTS;

Step 9), node X waits for the CTS of the destination node, if the network control frame is correctly received before the timeout, then go to step 10), if the verification error or timeout, turn off the timeout timer, add 1 to the number of backoffs, and then go to step 1);

Step 10), node X judges the type of the received network control frame, if the received network control frame is a CTS to be transmitted to node X, then close the timeout timer, go to step 11); if the received network control frame is For the CTS or DATA to be transmitted to other nodes, turn off the timeout timer, add 1 to the number of backoffs, set the silence timer, and go to step 1); if the received network control frame is the RTS sent by the destination node to node X, then Add 1 to the number of backoffs, and then go to step 1); if the received network control frame is an RTS sent by other nodes to node X, then go to step 5), and then back off and resend the DATA to be sent after the DATA is received; If the received network control frame is the RTS sent by other nodes to the destination node or the RTS sent between other nodes, discard the RTS, and then go to step 9);

Step 11), node X sends DATA, and then sets the timeout timer T _WFACK = 2×τ _max + T _ACK , where T _ACK is the duration of ACK;

Step 12), node X waits for the ACK of the destination node, if the network control frame is correctly received before the timeout, then go to step 13); if the verification is wrong, go to step 12); if it times out, add 1 to the number of backoffs, go to to step 1);

Step 13), node X judges the type of the received network control frame, if the received network control frame is an ACK for node X, then close the timeout timer, and go to step 14); RTS, then go to step 5), wait for the DATA to be received, and then back off and resend the DATA to be sent; if the node receives the xRTS, xCTS, and xDATA sent by the destination node to other nodes, it immediately stops waiting for ACK and enters the QUIET state. Set the silence timer, then go to step 1), and then back off and resend after step 1); otherwise, go to step 12);

Step 14), Node X judges the parity bit in the ACK. If the verification is correct, the number of backoffs is cleared, and go to step 1); otherwise, the number of backoffs is increased by 1, and go to step 1).

The present invention has the advantages of reducing the time wasted by nodes in the existing UW-CSMA/CA protocol by insisting on waiting, specifically:

(1) When the node is in the WFCTS state, if the node receives the RTS sent by the destination node to the node, it will enter the back-off state and re-compete for the channel; if the node receives the RTS sent by other nodes to the node, it will reply to the CTS and enter WFDTA state; if it receives an RTS that is not sent to the node, it discards and waits for the corresponding CTS; if the node monitors any xCTS, xDATA, it enters a silent state.

(2) When the node is in the WFDATA state, if the node receives the RTS sent by the source node to the node, it will reply to the CTS and reset the timeout period of the WFDATA state; if the node receives the xRTS and xCTS sent by the source node to other nodes , immediately end waiting for DATA and enter the QUIET state; if the node listens to any xDATA, it enters the silent state. Otherwise, keep waiting for the corresponding DATA until timeout.

(3) When the node is in the WFACK state, if the node receives the RTS sent by the destination node to the node, it will reply CTS, transfer to the received WFDATA state, and then back off and resend after receiving; if the node receives the RTS sent by the destination node When other nodes receive xRTS, xCTS, and xDATA, immediately stop waiting for ACK and enter the QUIET state, and back off and resend after the silence ends; otherwise, keep waiting for the corresponding ACK until timeout.

Compared with the prior art, the present invention has obvious improvement in throughput.

Description of drawings

FIG. 1 is a schematic diagram of the communication process between communication nodes of the underwater acoustic network in the existing UW-CSMA/CA protocol;

Fig. 2 is a flow chart of the multiple access method of the present invention;

Fig. 3 is the network topology structure schematic diagram that the present invention adopts when carrying out emulation;

Fig. 4 is a schematic diagram of the comparison results of the simulation of the throughput of the underwater acoustic network communication method using the multiple access method of the present invention and the prior art when the data packet length is 128Bytes, 256Bytes and 512Bytes, the communication rate in the simulation is 1024bps, The average grid spacing is 1000m;

Fig. 5 is a schematic diagram of the comparison result of the simulation of the throughput of the underwater acoustic network communication method using the multiple access method of the present invention and the prior art when the data packet length is 128Bytes, 256Bytes and 512Bytes, the communication rate in the simulation is 2048bps, The average grid spacing is 1000m;

Fig. 6 is a schematic diagram of the comparison result of the simulation of the throughput of the underwater acoustic network communication method using the multiple access method of the present invention and the prior art when the data packet length is 128Bytes, 256Bytes and 512Bytes, the communication rate in the simulation is 4096bps, The average grid spacing is 1000m;

Fig. 7 is a schematic diagram of the comparison results of the simulation of the throughput of the underwater acoustic network communication method using the multiple access method of the present invention and the prior art at a communication rate of 1024bps, 2048bps and 4096bps, and the length of the data packet in the simulation is 128Bytes, The average grid spacing is 1000m;

Fig. 8 is a schematic diagram of the comparison results of the simulation of the throughput of the underwater acoustic network communication method using the multiple access method of the present invention and the prior art at communication rates of 1024bps, 2048bps and 4096bps, and the length of the data packet in the simulation is 256Bytes, The average grid spacing is 1000m;

Fig. 9 is a schematic diagram of the comparison results of the simulation of the throughput of the underwater acoustic network communication method using the multiple access method of the present invention and the prior art at communication rates of 1024bps, 2048bps and 4096bps, the length of the data packet in the simulation is 512Bytes, The average grid spacing is 1000m;

Fig. 10 is a schematic diagram of the comparison results of simulation of the throughput of the underwater acoustic network communication method using the multiple access method of the present invention and the prior art when the average grid spacing is 500m, 1000m and 2000m, and the length of the data packet in the simulation is 256Bytes, the communication rate is 2048bps.

detailed description

The present invention will be further described now in conjunction with accompanying drawing.

With reference to Fig. 2, assume that node X is any node in the underwater acoustic network, the method of the present invention comprises the following steps:

Step 1), node X is in sleep state or waiting state. If the node receives an acoustic wakeup signal, go to step 2); if the backoff timeout and it has data to send, go to step 8); if the silence timeout and there is a paused backoff, continue to backoff and stay in the sleep state or waiting state; if the silence times out and there is no pause backoff, it will continue to sleep or wait; if it has data to send and is not in the backoff or silence state, set the backoff timer, and then continue to sleep or wait , if it has data to send and is in the backoff or silent state, it will continue to sleep or wait.

Step 2), node X wakes up and enters the state of receiving network control frames.

Step 3), if the receiving timeout, go to step 1), if the receiving verification is wrong, go to step 1); if a network control frame is received, check the destination address of the received network control frame, if the destination address is not Node X, then enter the quiet state, and then go to step 1), if the destination address is node X and is not quiet, then go to step 4), if the destination address is node X and is quiet, then go to step 1).

Step 4), judge the type of the received network control frame, if the control frame type is RTS, go to step 5), if it is other types, go to step 1);

Step 5), node X replies CTS to the source node, and then sets the timeout timer T _WFDATA =2×τ _max +T _DATA , where τ _max is the maximum propagation delay, and T _DATA is the duration of DATA;

Step 6), node X waits for DATA, if it receives DATA before the timeout, then go to step 7), if the node receives the RTS sent by the source node to the node, then go to step 5); if the node receives the source node When sending xRTS or xCTS to other nodes, immediately end waiting for DATA, and enter the silent state, set the silent timer, go to step 1); if the node listens to any xDATA, enter the silent state, set the silent timer, go to step 1), else go to step 1).

Step 7), turn off the timeout timer, and then verify the received DATA, if the verification is correct, pass the DATA to the network layer, if it is incorrect, discard the DATA; then reply ACK according to the verification result, and finally go to the step again 1).

Step 8), node X sends RTS, and sets a timeout timer T _WFCTS =2×τ _max +T _CTS , where τ _max is the maximum propagation delay, and T _CTS is the duration of CTS.

Step 9), node X waits for the CTS of the destination node, if the network control frame is correctly received before the timeout, then go to step 10), if the verification error or timeout, turn off the timeout timer, add 1 to the number of backoffs, and then go to step 1).

Step 10), node X judges the type of the received network control frame, if the received network control frame is a CTS to be transmitted to node X, then close the timeout timer, go to step 11); if the received network control frame is For the CTS or DATA to be transmitted to other nodes, turn off the timeout timer, add 1 to the number of backoffs, set the silence timer, and go to step 1); if the received network control frame is the RTS sent by the destination node to node X, then Add 1 to the number of backoffs, and then go to step 1); if the received network control frame is an RTS sent by other nodes to node X, then go to step 5), and then back off and resend the DATA to be sent after the DATA is received; If the received network control frame is an RTS sent by other nodes to the destination node or an RTS sent between other nodes, discard the RTS, and then go to step 9).

Step 11), node X sends DATA, and then sets the timeout timer T _WFACK =2×τ _max +T _ACK , where τ _max is the maximum propagation delay, and T _ACK is the duration of ACK.

Step 12), node X waits for the ACK of the destination node, if the network control frame is correctly received before the timeout, then go to step 13); if the verification is wrong, go to step 12); if it times out, add 1 to the number of backoffs, go to to step 1).

Step 13), node X judges the type of the received network control frame, if the received network control frame is an ACK for node X, then close the timeout timer, and go to step 14); RTS, then go to step 5), wait for the DATA to be received, and then back off and resend the DATA to be sent; if the node receives the xRTS, xCTS, and xDATA sent by the destination node to other nodes, it immediately stops waiting for ACK and enters the QUIET state. Set the silence timer, then go to step 1), and then back off and resend after step 1) is over; otherwise, go to step 12).

Step 14), Node X judges the parity bit in the ACK. If the verification is correct, the number of backoffs is cleared, and go to step 1); otherwise, the number of backoffs is increased by 1, and go to step 1).

The above is a description of the basic steps of the method of the present invention. Compared with the prior art, the method of the present invention is to reduce the time wasted by nodes in the existing UW-CSMA/CA protocol by insisting on waiting, specifically:

(1) When the node is in the WFCTS state, if the node receives the RTS sent by the destination node to the node, it will enter the back-off state and re-compete for the channel; if the node receives the RTS sent by other nodes to the node, it will reply to the CTS and enter WFDTA state; if it receives an RTS that is not sent to the node, it discards and waits for the corresponding CTS; if the node monitors any xCTS, xDATA, it enters a silent state.

(2) When the node is in the WFDATA state, if the node receives the RTS sent by the source node to the node, it will reply to the CTS and reset the timeout period of the WFDATA state; if the node receives the xRTS and xCTS sent by the source node to other nodes , immediately end waiting for DATA and enter the QUIET state; if the node listens to any xDATA, it enters the silent state. Otherwise, keep waiting for the corresponding DATA until timeout.

(3) When the node is in the WFACK state, if the node receives the RTS sent by the destination node to the node, it will reply CTS, transfer to the received WFDATA state, and then back off and resend after receiving; if the node receives the RTS sent by the destination node When other nodes receive xRTS, xCTS, and xDATA, immediately stop waiting for ACK and enter the QUIET state, and back off and resend after the silence ends; otherwise, keep waiting for the corresponding ACK until timeout.

Therefore, the method of the present invention has a significant increase in throughput.

Next, the method of the present invention is compared with the prior art through simulation.

In the present invention, NS2 is used for simulation analysis. The network topology used in the simulation is shown in Figure 3, and 36 static nodes (black nodes in Figure 3) form a 6×6 square distribution. Nodes are not exactly located at grid intersections, but a random offset of 10% grid spacing is introduced both horizontally and vertically. The maximum communication distance of a node is 1.75 times the grid spacing, so each node has 8 one-hop neighbors and 16 two-hop neighbors. In the simulation, all 36 nodes generate data packets according to Poisson distribution, and the rate of generating data packets is the same. Each data packet generated by a node is sent to any two-hop neighbor node, and each data packet has the same probability of being sent to 16 two-hop neighbor nodes. In order to make the nodes on the boundary also have 16 two-hop neighbor nodes, the boundary needs to be expanded, that is, two layers of nodes (gray nodes) are expanded in all four directions, but these additional nodes will not generate data flow, but only serve as the boundary Node's destination node and forwarding node exist. The simulation adopts static routing, and the figure only shows the static routing of one node (circular node), and the routing of other nodes is similar.

In the simulation process of the present invention, the speed of sound is taken as 1500m/s. In the simulation process, the load of the existing technology (UW-CSMA/CA) under different data packet lengths, different communication rates and different grid spacings and the underwater acoustic network communication method using the multiple access method of the present invention- Throughput for simulation comparison.

The definition of the whole network load and throughput involved in the simulation process is as follows:

Fig. 4 is a schematic diagram of the comparison results of the simulation of the throughput of the underwater acoustic network communication method using the multiple access method of the present invention and the prior art when the data packet length is 128Bytes, 256Bytes and 512Bytes, the communication rate in the simulation is 1024bps, The average grid spacing is 1000m.

Fig. 5 is a schematic diagram of the comparison result of the simulation of the throughput of the underwater acoustic network communication method using the multiple access method of the present invention and the prior art when the data packet length is 128Bytes, 256Bytes and 512Bytes, the communication rate in the simulation is 2048bps, The average grid spacing is 1000m.

Fig. 6 is a schematic diagram of the comparison result of the simulation of the throughput of the underwater acoustic network communication method using the multiple access method of the present invention and the prior art when the data packet length is 128Bytes, 256Bytes and 512Bytes, the communication rate in the simulation is 4096bps, The average grid spacing is 1000m.

It can be seen from Figure 4, Figure 5 and Figure 6 that as the length of the data packet increases, the single communication efficiency of the protocol increases after the handshake is successful, and the throughput of the two protocols is improved. Under the same data packet length, the throughput of the underwater acoustic network communication method adopting the multiple access method of the present invention is obviously higher than that of the prior art.

Fig. 7 is a schematic diagram of the comparison results of the simulation of the throughput of the underwater acoustic network communication method using the multiple access method of the present invention and the prior art at a communication rate of 1024bps, 2048bps and 4096bps, and the length of the data packet in the simulation is 128Bytes, The average grid spacing is 1000m.

Fig. 8 is a schematic diagram of the comparison results of the simulation of the throughput of the underwater acoustic network communication method using the multiple access method of the present invention and the prior art at communication rates of 1024bps, 2048bps and 4096bps, and the length of the data packet in the simulation is 256Bytes, The average grid spacing is 1000m.

Fig. 9 is a schematic diagram of the comparison results of the simulation of the throughput of the underwater acoustic network communication method using the multiple access method of the present invention and the prior art at communication rates of 1024bps, 2048bps and 4096bps, the length of the data packet in the simulation is 512Bytes, The average grid spacing is 1000m.

It can be seen from Figure 7, Figure 8 and Figure 9 that as the communication rate increases, the sending time of the data packet decreases, while the propagation delay does not decrease correspondingly, the communication efficiency decreases, and the throughput of the two protocols will decrease. Under the same communication rate, the throughput of the underwater acoustic network communication method adopting the multiple access method of the present invention is obviously higher than that of the prior art.

Fig. 10 is a schematic diagram of the comparison results of simulation of the throughput of the underwater acoustic network communication method using the multiple access method of the present invention and the prior art when the average grid spacing is 500m, 1000m and 2000m, and the length of the data packet in the simulation is 256Bytes, the communication rate is 2048bps.

It can be seen from Figure 10 that as the average grid spacing increases, the propagation delay increases, the RTS-CTS handshake time prolongs, the communication efficiency decreases, and the throughput of both protocols decreases. Under the same average grid spacing, the throughput of the underwater acoustic network communication method adopting the multiple access method of the present invention is obviously higher than that of the prior art.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than limit them. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent replacements to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all of them should be included in the scope of the present invention. within the scope of the claims.

Claims (1)

1. A multiple access method based on UW-CSMA/CA in underwater acoustic network communication, comprising: Step 1), node X is in sleep state or waiting state; if the node receives an acoustic wake-up signal, go to step 2); if the backoff timeout and it has data to send, then go to step 8); if the silence timeout and there is If the backoff is paused, it will continue to backoff and continue to be in the sleeping or waiting state; if the silence times out and there is no paused backoff, it will continue to be in the sleeping or waiting state; if it has data to send and is not in the backing off or silent state, set Set the backoff timer, and then continue to be in the sleeping state or waiting state; if it has data to send and is in the backoff or silent state, it will continue to be in the sleeping state or waiting state; Step 2), node X is woken up, and transfers to the network control frame receiving state; Step 3), if receiving overtime then go to step 1), if receiving verification error, then go to step 1); if receiving network control frame, check the destination address of the received network control frame, if the destination address is not Node X, then enter the silent state, and then go to step 1), if the destination address is node X and is not silent, then go to step 4), if the destination address is node X and is silent, then go to step 1); Step 4), judge the type of the received network control frame, if the control frame type is RTS, go to step 5), if it is other types, then go to step 1); Step 5), node X responds to the CTS to the source node, and then sets the timeout timer T _WFDATA =2×τ _max +T _DATA , where τ _max is the maximum propagation delay, and T _DATA is the duration of DATA; Step 6), node X waits for DATA, if it receives DATA before the timeout, then go to step 7), if the node receives the RTS sent by the source node to this node, then go to step 5); if the node receives the RTS from the source node When sending xRTS or xCTS to other nodes, stop waiting for DATA immediately, and enter the silent state, set the silent timer, go to step 1); if the node listens to any xDATA, enter the silent state, set the silent timer, go to step 1); otherwise go to step 1); Step 7), close the timeout timer, then check the received DATA, if the check is correct, pass the DATA to the network layer, if it is not correct, discard the DATA; then reply ACK according to the check result, and finally go to the step again 1); Step 8), node X sends RTS, and sets timeout timer T _WFCTS =2×τ _max +T _CTS , wherein, T _CTS is the duration of CTS; Step 9), node X waits for the CTS of the destination node, if the network control frame is correctly received before the timeout, then go to step 10), if the verification error or timeout, then close the timeout timer, add 1 to the backoff times, and then go to step 1); Step 10), node X judges the network control frame type that receives, if the received network control frame is the CTS that will be transmitted to node X, then close the overtime timer, go to step 11); If the received network control frame is For CTS or DATA to be transmitted to other nodes, turn off the timeout timer, add 1 to the number of backoffs, set the silent timer, and go to step 1); if the received network control frame is the RTS sent by the destination node to node X, then Add 1 to the number of backoffs, and then go to step 1); if the received network control frame is an RTS sent by other nodes to node X, then go to step 5), and then back off and resend the DATA to be sent after the DATA is received; If the received network control frame is the RTS sent to the destination node by other nodes or the RTS sent to each other between other nodes, then discard the RTS, and then go to step 9); Step 11), node X sends DATA, and then sets the timeout timer T _WFACK =2×τ _max +T _ACK , where T _ACK is the duration of ACK; Step 12), node X waits for the ACK of the destination node, if the network control frame is correctly received before the timeout, then go to step 13); if the check is wrong, then go to step 12); to step 1); Step 13), node X judges the type of the network control frame received, if the received network control frame is an ACK for node X, then close the timeout timer, and go to step 14); RTS, then go to step 5), wait for the DATA to be received, and then back off and resend the DATA to be sent; if the node receives the xRTS, xCTS, and xDATA sent by the destination node to other nodes, it immediately stops waiting for ACK and enters the QUIET state. Set the silence timer, then go to step 1), and then back off and resend after step 1) is over; otherwise, go to step 12); Step 14), node X judges the check bit in the ACK, if the check is correct, the number of backoffs is cleared, and then go to step 1); otherwise, the number of backoffs is increased by 1, and then go to step 1).