CN107222903A - Method of data capture based on constructive interference in asynchronous low duty ratio WSN - Google Patents

Abstract

The invention discloses a data collection method based on constructive interference in an asynchronous low duty ratio WSN. The data collection method is to randomly distribute n sensor nodes in an area with an area of M×M square meters to form a wireless sensor network , the sensor nodes include at least a Source node, a forwarding node, and a Sink node. Except for the Sink node, other sensor nodes in the wireless sensor network use the asynchronous LPP mechanism for sleep scheduling. During the network initialization process, the sensor nodes will perform Hierarchical selection to obtain the number of hops from the sensor node to the sink node. When there is data to be sent, the source node selects the awakened forwarding node in the network to transmit the data concurrently to the sink node. After the concurrent transmission is completed, the source node and the forwarding node return to the LPP Sleep scheduling state. The invention can effectively reduce the control overhead in the network, improve the receiving rate of data packets, and reduce end-to-end delay and network energy consumption.

Description

Data collection method based on constructive interference in asynchronous low duty cycle WSN

technical field

The invention relates to the technical field of wireless sensor networks, in particular to a data collection method based on constructive interference in an asynchronous low duty cycle WSN.

Background technique

Constructive interference is applied to the data transmission of wireless sensor network (WSN), which can realize concurrent transmission of data, and has a data packet reception rate close to 100% and very low data transmission delay. Based on constructive interference Concurrent transmission has the following characteristics: (1) In the process of concurrent transmission, the same data packet is transmitted; (2) When multiple nodes send data to the same node at the same time, they need to meet the condition of constructive interference; (3) Nodes do not Neighbor and routing information will be saved; (4) All nodes participate in concurrent transmission; therefore, when concurrent transmission based on constructive interference is applied to the data collection protocol, such nodes will not need to maintain neighbor node information and routing status information, Reduce network energy consumption and improve packet reception rate. However, concurrent transmission requires all nodes to participate in data transmission, resulting in large energy consumption. Therefore, we need to combine a low duty cycle mechanism, only some nodes need to participate in concurrent transmission, and nodes that do not need to participate will go to sleep. In order to reduce the energy consumption of the network.

However, in event-based monitoring-driven applications such as environmental monitoring and medical fields, sensor nodes often do not perform continuous and high-frequency data collection, but send status messages or collected information when an event (forest fire, etc.) occurs Sent to the Sink node (Sink node, also known as the sink node), the current existing data collection protocol is mainly based on unicast forwarding to reduce unnecessary transmission of nodes. In the data collection protocol based on unicast forwarding, a node selects a parent node from its neighbor nodes for data transmission, and finally routes the data packet to the Sink node. Affected by the environment, node energy and other factors, the information of neighbor nodes may be sent and changed in real time. Therefore, in these protocols, in order to ensure the robustness of routing, nodes need to maintain neighbor information regularly, and the energy consumed in the maintenance process is relatively large. While awake, the maintenance process will become more complicated. Therefore, in a low-duty-cycle wireless sensor network, the asynchronous duty-cycle mechanism does not need clock synchronization and does not need to know the sleep schedule of neighbor nodes, which can extend the network life cycle more effectively. In an asynchronous duty cycle network, compared with the LPL (Low Power Listen, low-power listening) mechanism, the LPP (Low Power Listen, low-power acquisition) mechanism is suitable for the application scenario of waking up some nodes in the network. As the scale increases, the performance of the LPP mechanism will be better. Therefore, in the low-duty-cycle sensor network using the asynchronous LPP mechanism, we propose a data collection protocol ADCCI (Asynchronous Duty Cycle and Constructive Interference) based on constructive interference. The Sink node does not need to save and maintain neighbor information to reduce End-to-end latency and network energy consumption.

Contents of the invention

The purpose of the present invention is to provide a data collection method based on constructive interference in an asynchronous low duty cycle WSN. According to the data collection method of the present invention, the control overhead in the network can be effectively reduced, the data packet reception rate can be improved, and the end-to-end delay can be reduced. and network energy consumption, in order to achieve the above object, the present invention adopts the following technical effects:

According to one aspect of the present invention, a data collection method based on constructive interference in an asynchronous low duty cycle WSN is provided, the data collection method includes the following steps: randomly distributing n sensor nodes in an area of M×M square A wireless sensor network is formed within an area of 1 m, where n is an integer greater than 1, and the sensor nodes include at least a Source node, a forwarding node, and a Sink node. Except for the Sink node, other sensor nodes in the wireless sensor network use The asynchronous LPP mechanism performs sleep scheduling. During the network initialization process, the sensor node will perform layer selection to obtain the number of hops from the sensor node to the sink node. When there is data to be sent, the source node selects the awakened forwarding node in the network for data forwarding. The forwarding node receives the data packet sent by the Source node and concurrently transmits the data packet to the Sink node. After the concurrent transmission is completed, the Source node and the forwarding node return to the LPP sleep scheduling state.

Preferably, in the network initialization process, the layer selection of sensor nodes includes the following steps:

Step 21: The Sink node broadcasts a Packet (hop=0) data packet, where hop represents the number of hops away from the Sink node;

Step 22: Any sensor node v _i (i∈n) in the network receives the data packet Packet(v _j .hop) broadcast by the neighbor node v _j (j∈n,j≠i), if v _i .hop< ＝v _j .hop-1, set the hop of node v _i to v _i .hop=v _j .hop+1, and then continue to broadcast Packet(v _i .hop) packets until all nodes in the network reach For the hop count of the Sink node, the node with hop=k is named as a k-layer node, where k is an integer greater than or equal to 1, and the k-layer node only needs to store hop information, and does not need to store any information about adjacent layer nodes.

Preferably, during the network initialization process, the sensor nodes only need to perform layer selection once, and after the network initialization is completed, the sensor nodes perform sleep scheduling according to the LPP mechanism.

Preferably, when the Source node of the k layer has data to send, the Source node will listen to the network channel for a period of time, and wait for the neighbor node to wake up and send a probe packet to establish a connection. After the connection is established, the neighbor node receives the awake data sent by the Source node packet to prolong the wake-up time of neighbor nodes; the Source node sends the awake data packet to the Sink node at last, and after the Sink node receives the awake data packet, after the T _backoff waiting time, the Sink node sends the feedback packet to the Source node, T _backoff The waiting time ensures that all probe packets and awake packets that are being transmitted are at least two hops away from the Sink. When the Sink node in the network receives the awake packet, it will process it according to the following three situations:

Situation 41: Nodes at layer k=(k≥hop) will be directly discarded and enter a sleep state to prevent nodes at layer k=(k≥hop) from participating in this concurrent transmission to reduce network energy consumption;

Situation 42: Neighbor nodes at layer k-1 will add their own hop(k-1) information when forwarding awake packets; k=(k>hop(k-1)) neighbor nodes at layer receive the awake packets Directly discard and go to sleep; k-2 layer nodes will cover hop(k-1) with hop(k-2) before forwarding after receiving the awake data packet, k-2 layer nodes continue to execute the same as hop(k- 1) Nodes operate in the same way;

Situation 43: The forwarding node that has processed the awake data packet and remains awake is not affected by the awake packet sent by the upper layer node;

Preferably, the Sink node will send the feedback packet to the Source node after receiving the awake packet, and the forwarding node that the Source node receives the feedback packet will process according to the following three situations:

Situation 51: The Source node receives the feedback data packet, but does not receive the awake data packet, the Source node will discard the feedback data packet and enter the sleep state;

Situation 52: The forwarding node at k=(k≥hop) level will directly discard the feedback packet and enter the sleep state;

Situation 53: The forwarding nodes at the same level will simultaneously receive the feedback data packet sent by the upper level node, and the forwarding node will directly copy the data from the receiving queue to the sending queue for sending without any processing, and finally the feedback data packet will be Concurrent transmissions arrive at the Source node, and constructive interference occurs at the Source node.

Preferably, after the T _backoff waiting time, the Sink node sends the feedback packet to the Source node, and when the feedback data packet arrives at the Source node, the Source node initiates concurrent transmissions with an interval of T _count after the T _wait waiting time. What is transmitted at the same time is the data packet collected by the sensor node; after the forwarding nodes at the same level receive the data packet at the same time, there will be a fixed waiting time T _process before sending the data packet, so the condition of constructive interference is satisfied. At this time, the forwarding node on the path from the Source node to the Sink node will not initiate a probe packet or an awake packet, so T _wait < T _backoff is satisfied;

After the Source node starts concurrent transmission, if it does not hear the k=(hop-1) layer node forwarding the data packet after 2×T _process , it will retransmit to increase the reliability of the transmission; if it detects and caches the queue There is also a data Source node that will continue to send data at T _count = 2×T _process .

Preferably, after the concurrent transmission is completed, the forwarding node returns to the LPP sleep scheduling state. After the data transmission is completed, the forwarding node on the transmission path is notified by an implicit termination method or an explicit termination method that the transmission has been completed, and then enters the sleep state. After that, The forwarding node will perform sleep scheduling according to LPP.

Preferably, in the implicit termination mode, the forwarding node participating in the concurrent transmission obtains the number of data packets from the awake packet, and the forwarding node enters sleep after forwarding the last data packet; in the display termination mode, the Sink After the node receives all count data packets, it will send a confirmation ACK, otherwise it will send a negative confirmation NACK, and the forwarding node participating in the concurrent transmission will terminate the concurrent transmission stage and go to sleep after forwarding the ACK or NACK.

The present invention has adopted above-mentioned technical scheme, the present invention has following technical effect:

(1) The present invention can effectively reduce the control overhead in the network, improve the data packet receiving rate, reduce end-to-end delay and network energy consumption, and is especially suitable for the application field of event-driven sensor monitoring.

(2) The Sink node of the present invention does not need to save and maintain neighbor information and routing status information, which can greatly reduce end-to-end delay and network energy consumption, and only use concurrent transmission based on constructive interference when there is data to send. Fast and reliable The data is sent to the Sink node, thereby improving the data packet reception rate; the invention combines a low duty cycle mechanism, only some nodes need to participate in concurrent transmission, and the nodes that do not need to participate go to sleep, which can reduce the energy consumption of the network .

(3) In the low duty cycle wireless sensor network of the present invention, the asynchronous duty cycle mechanism does not require clock synchronization, and does not need to know the sleep schedule of neighbor nodes, which can more effectively extend the network life cycle.

Description of drawings

FIG. 1 is a schematic diagram of the distribution of sensor nodes in the wireless sensor network of the present invention.

Fig. 2 is a schematic diagram of the operation of the Sink node processing data in the whole protocol of the present invention.

Fig. 3 is a flow chart of the data collection process of the sensor node of the present invention.

Fig. 4 is a schematic diagram of LPP sleep scheduling in the present invention.

Fig. 5 is a schematic diagram of changes in the data packet receiving rate under different data packet generation intervals of the present invention;

FIG. 6 is a schematic diagram of changes in duty cycle under different data packet generation intervals according to the present invention.

FIG. 7 is a schematic diagram of changes in data transmission delay under different data packet generation intervals in the present invention.

FIG. 8 is a schematic diagram of the variation of the proportion of the concurrent transmission phase to the data transmission delay under different data packet generation intervals in the present invention.

FIG. 9 is a schematic diagram of changes in the average overhead required to send each data packet under different data packet generation intervals in the present invention.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below with reference to the accompanying drawings and preferred embodiments. However, it should be noted that many of the details listed in the specification are only for readers to have a thorough understanding of one or more aspects of the present invention, and these aspects of the present invention can be implemented even without these specific details.

As shown in Figure 1, the data collection method based on constructive interference in an asynchronous low duty cycle WSN according to the present invention includes the following steps: randomly distributing n sensor network nodes in an area with an area of M×M square meters In, where n is an integer greater than 1, the sensor node includes at least Source node, forwarding node and 1 Sink node, except the Sink node, other sensor nodes in the wireless sensor network adopt the asynchronous LPP mechanism for sleep scheduling, During the network initialization process, the sensor node will perform hierarchical selection to obtain the hops from the sensor node to the sink node. When there is data to be sent, the source node selects the forwarding node that is awake in the network to forward the data, and the forwarding node receives the data sent by the source node Packet and concurrently transmit the data packet to the Sink node. After the concurrent transmission is completed, the Source node and the forwarding node return to the LPP sleep scheduling state. When the sensor node collects data and needs to send the data to the sink node, we call this node the source node (Source node), and in the sensor network, the sensor node that helps the source node send data to the sink node, we call it It is a forwarding node (Node node).

(1) When the Source node wants to send data, it will always listen to the channel and wait for the neighbor node to wake up and send a probe data packet. After the Source node receives the probe data packet, it will send an ACK to establish a connection, and the Source node will send an awake data at this time. Package to the Sink node.

(2) After receiving the awake data packet, the Sink node returns a feedback data packet (feedback packet) after waiting for a period of time (to avoid conflict with the probe data packet and the awake data packet). The forwarding node Node1 and the forwarding node Node2 are in the same hop, as shown in Figure 1, Figure 2 and Figure 3, so both will receive the feedback packet at the same time. The forwarding node Node1 and the forwarding node Node2 will directly send the feedback packet without any processing, and the feedback packet will arrive at the Source node at the same time, resulting in constructive interference.

(3) After the source node receives the feedback packet, it will consider that the nodes on the path to the sink node are ready for concurrent transmission. The Source node sends data after waiting for a period of time (to avoid conflict with the Sink's feedback packet), and the Node1 forwarding node and Node2 forwarding node will receive the packet at the same time, and then send it directly, which also produces constructive interference at the Sink node.

(4) Finally, the network can end the data transmission by means of explicit termination or implicit termination, and the Source node, Node1 forwarding node, and Node2 forwarding node go to sleep, and then perform sleep scheduling according to LPP.

In the initialization network process among the present invention, the layer selection of Sink node location comprises the following steps:

Step 21: the Sink node broadcasts a Packet (hop=0) data packet, wherein hop represents the number of hops away from the Sink node; so that the Source node obtains its own hop number to the Sink node;

Step 22: Any sensor node v _i (i∈n) in the network receives the data packet Packet(v _j .hop) broadcast by the neighbor node v _j (j∈n,j≠i), if v _i .hop< ＝v _j .hop-1, set the hop of node v _i to v _i .hop=v _j .hop+1, and then continue to broadcast Packet(v _i .hop) packets until all nodes in the network reach For the hop count of the Sink node, the node with hop=k is named as a k-layer node, where k is an integer greater than or equal to 1, and the k-layer node only needs to store hop information, and does not need to store any information about adjacent layer nodes. During the network initialization process, that is, within the network life cycle, the sensor nodes only need to perform a layer selection. After the network initialization is completed, the sensor nodes perform sleep scheduling according to the LPP mechanism. In the present invention, combined with Fig. 1 and Fig. 2 3 and Figure 4, the LPP mechanism performs sleep scheduling as follows:

When the Source node at the k=hop layer has data to send, the Source node will listen to the network channel for a period of time T _listen , and wait for the neighbor node to wake up and send a probe packet to establish a connection. After the connection is established, the neighbor node receives the awake sent by the Source node Data packet is to prolong the wake-up time of neighbor node; Described Source node sends the awake data packet and will reach Sink node finally, after Sink node receives the awake data packet, after T _backoff waiting time, Sink node sends feedback packet to Source node, T The _backoff wait time ensures that all probe packets and awake packets being transmitted are at least two hops away from the Sink.

After the T _backoff waiting time, the Sink node sends a feedback packet to the Source node. After the feedback data packet arrives at the Source node, the Source node initiates concurrent transmission with an interval of T _count after the T _wait waiting time. At this time, the transmission is the data packet collected by the sensor node; after the forwarding nodes at the same level receive the data packet at the same time, there will be a fixed waiting time T _process before sending the data packet, so the condition of constructive interference is satisfied. At this time, Source The forwarding node on the path from the node to the Sink node will not initiate a probe data packet or an awake data packet, so T _wait < T _backoff is _satisfied ; after the Source node starts concurrent transmission, if no k=( The hop-1) layer node forwards the data packet and retransmits it to increase the reliability of the transmission; if it detects and there is still data in the cache queue, the Source node will continue to send data at T _count = 2×T _process . In the present invention, when the Sink node in the sensor network receives the awake packet, it will be processed according to the following three situations:

Situation 41: Nodes at layer k=(k≥hop) will be directly discarded and enter a sleep state to prevent nodes at layer k=(k≥hop) from participating in this concurrent transmission to reduce network energy consumption;

Situation 42: Neighbor nodes at layer k-1 will add their own hop(k-1) information when forwarding awake packets; k=(k>hop(k-1)) neighbor nodes at layer receive the awake packets Directly discard and go to sleep; k-2 layer nodes will cover hop(k-1) with hop(k-2) before forwarding after receiving the awake data packet, and continue to perform the same operation as hop(k-1) node ;

Situation 43: The forwarding node that has processed the awake packet and remains awake is not affected by the awake packet sent by the upper layer node; the Sink node will send a feedback packet to the Source node after receiving the awake packet, and the Source The forwarding node that the node receives the feedback packet will process according to the following three situations:

Situation 51: The node receives the feedback data packet, but does not receive the awake data packet, the Source node will discard the feedback data packet and enter the sleep state;

Case 52: The forwarding nodes at k=(k≥hop) level will directly discard the feedback data packet and enter the sleep state.

Situation 53: The forwarding nodes at the same level will simultaneously receive the feedback data packet sent by the upper level node, and the forwarding node will directly copy the data from the receiving queue to the sending queue for sending without any processing, and finally the feedback data packet will be Concurrent transmission arrives at the Source node, and constructive interference occurs at the Source node;

In the present invention, the forwarding node receives the Source node data packet and concurrently transmits the data packet to the Sink node. After the concurrent transmission is completed, the Sink node sends the feedback data packet to the Source node; when the feedback data packet arrives at the source node, the source node ( Source node) initiates a transmission with an interval of T _count (a total of count data packets) after the waiting time is T _wait (in order to avoid conflict with the ongoing feedback data packet transmission), and the forwarding nodes at the same level receive the data at the same time After the data packet is sent, there will be a fixed waiting time T _process before sending the data packet. From receiving the data packet to sending the data packet, the waiting time generated by this process is defined as T _process . Therefore, nodes at the same level meet the condition of constructive interference, which increases the reliability of end-to-end. When k=1 layer nodes send the same data to the sink node at the same time, constructive interference occurs, which further improves the probability of successful packet reception.

The forwarding node records the metadata (Metadata) of the forwarded data packet, so the data packet will not be resent to prevent the problem of circular forwarding. At this stage, the source node starts to perform concurrent transmission and the nodes on the path to the sink will not initiate probe packets or awake packets, so set T _wait < T _backoff .

After the source node starts concurrent transmission, if it does not hear the k=(hop-1) layer node forwarding the data packet after 2×T _process , it will retransmit to increase the reliability of the transmission; There is still data, and the source node will continue to send data at T _count =2×T _process .

After the concurrent transmission is completed, the forwarding node returns to the LPP sleep scheduling state. After the data transmission is completed, the forwarding node on the transmission path is notified by the implicit termination method or the explicit termination method that the transmission has completed, and then enters the sleep state. Thereafter, the node will perform dormancy scheduling according to LPP. In the implicit termination mode, the forwarding nodes participating in concurrent transmission obtain the number of data packets from the awake data packet, and the node enters sleep after forwarding the last data packet; this implicit The mode of transmission is relatively simple, but the forwarding node will always listen to the channel after the data packet is lost, so the node is set in the ADCCI protocol to exit the concurrent transmission phase and enter sleep after Timeout(TX(h)).

In the display termination method, after receiving all count data packets, the Sink node will send a confirmation ACK, otherwise it will send a negative confirmation NACK, and the forwarding nodes participating in the concurrent transmission will terminate the concurrent transmission stage after forwarding the ACK or NACK. sleep. Although the explicit termination method generates extra time for transmitting ACK or NACK, the explicit termination method can reduce the timeout time Timeout(TX(h)) of nodes in a network with a high packet loss rate.

In the present invention, 50 nodes are selected to be set in a square area of 100× ^100m2 , the Sink node is located in the center of this area, and each node generates a data packet (20Bytes) within the data packet generation interval and passes the packet through multiple hops Routing to the Sink node. In this example, the ADCCIs all employ an explicit termination scheme. In the ADCCI protocol, the basic parameter settings are shown in Table 1

Table 1: ADCCI parameter settings

In the present invention, by using the data collection protocol Tree-based Hop-by-hopReliable Data Collection (hereinafter referred to as THRDC) on Contiki as a comparison protocol, this agreement is the realization of Collection TreeProcotol (CTP) on Contiki, and CTP is under LPL mode The performance is better than in LPP mode, so we use the X-MAC protocol to provide sleep scheduling for THRDC, as shown in Figure 4, set the T _wakeup of X-MAC to be consistent with the value of ADCCI. Link quality and other parameters are in accordance with the system default. In this chapter, we use the data packet generation interval to represent the time interval between two events, and the duty cycle is defined as: T (the average radio open time of each node in the data packet generation interval)/T (data packet generation interval), As shown in Figure 5 and Figure 6, it can be seen from Figure 5 that the data packet reception rate of ADCCI is close to 100%, while that of THRDC is around 94%. Because in ADCCI, due to constructive interference, the reliability between node layers is higher and there are multiple paths in the network to transmit data at the same time, and finally constructive interference at the sink node further increases the probability of reception. When THRDC transmits data, each hop is the node with the smallest value of ETX (Expected Transmission Count, expected number of transmissions). When data transmission fails, update ETX and wait for the node with the smallest ETX value to wake up again. If the ETX value changes greatly, the sending node will also broadcast to notify other nodes to update the route, thereby increasing the transmission delay and node wake-up time. From the duty cycle in Fig. 6, it is also proved that in the same data packet generation interval, the THRDC protocol radio is turned on for a longer time. Therefore, it can be concluded from Fig. 6 that compared to THRDC, ADCCI improves the packet reception rate by 5.8% while reducing the duty cycle by 24.6%.

In the present invention, as shown in Figure 7, the average end-to-end delay and concurrent transmission delay, as can be seen from Figure 7, under different data packet generation intervals, the average end-to-end delay of THRDC is 12.78s, ADCCI's It's 9.95s. Therefore, compared to THRDC, ADCCI can reduce the end-to-end delay by 22.1%. It can be seen from Figure 8 that the delay generated in the concurrent transmission stage accounts for 8.9% of the ADCCI average end-to-end delay (average 0.89s), and 91.1% of the time is preparing for the concurrent transmission stage. The delay generated in the concurrent transmission phase does not change much, so the proportion of the concurrent transmission phase decreases with the increase of the average end-to-end delay. Therefore, when the data packet generation interval is equal to 1200s and 2400s, two minimum value. It can be seen from Figure 7 and Figure 8 that concurrent transmission based on constructive interference is a low-latency data transmission method.

Control overhead, the experiment compares the number of control packets required to transmit each data packet under different data packet generation intervals during the entire process of data transmission between ADCCI and THRDC. The smaller the average overhead of each data packet, it means that the transmission of each The less energy consumed by the entire network of the data packet, the higher the energy utilization rate. In the X-MAC protocol, the node will continuously send beacon frames before the next hop node starts to receive the data packet. We will use the number of beacon frames sent continuously Count as 1.

When the data packet generation interval is small, the number of control packets required by THRDC is small, but as the data packet generation interval increases, this overhead will increase rapidly, because although there is no data to be sent in the network, THRDC The protocol needs to regularly maintain the routing state and generate control packet overhead. However, ADCCI nodes only generate control packets when there are data packets to be sent, so as the data packet generation interval increases, the required control packets for each data packet do not change significantly, which shows that the data in Figure 7 When the packet generation interval is equal to 1800s, the duty cycle of THRDC does not decrease further, while the duty cycle of ADCCI shows a downward trend.

Combining Figure 6 and Figure 9, the network energy consumption of ADCCI and THRDC is analyzed. The radio module in the sensor node is the most energy-consuming unit, and Figure 6 shows that in the same packet generation interval, the ADCCI radio module is turned on for 24.6% less time than THRDC. Figure 9 shows that the average control packet overhead required for each data in the ADCCI protocol has almost no change in different data packet generation intervals, so compared with THRDC, ADCCI can effectively reduce network energy consumption.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications should also be It is regarded as the protection scope of the present invention.

Claims (8)

1. the method for data capture based on constructive interference in asynchronous low duty ratio WSN, it is characterised in that：The method of data capture Comprise the following steps：N sensor node is randomly distributed in the region that an area is M × M square metres and forms wireless Sensor network, wherein, n is the integer more than 1, at least including Source nodes, forward node and 1 in sensor node Sink node, in addition to Sink node, the other sensors node in wireless sensor network is all slept using asynchronous LPP mechanism Sleep and dispatch, in network initialization procedure, sensor node can carry out hierarchy selection and be saved so as to obtain sensor node to Sink The hop count of point, when there is data to need transmission, the forward node revived in Source nodes selection network carries out data forwarding, turns Send out node and receive Source nodes transmission packet and by the packet concurrent transmission to Sink node, after concurrent transmission is finished, Source nodes return to LPP sleep scheduling states with forward node.

2. the method for data capture based on constructive interference in described asynchronous low duty ratio WSN according to claim 1, it is special Levy and be：In network initialization procedure, sensor node carries out hierarchy selection and comprised the following steps：

Step 21：Sink node broadcasts Packet (hop=0) packet, and wherein hop represents the jump apart from Sink node Number；

Step 22：Any one sensor node v in network_i(i ∈ n) receives neighbor node v_j(j ∈ n, j ≠ i) broadcast Packet Packet (v_j.hop), if v_i.hop<=v_j.hop-1 then by node v_iHop be set to v_i.hop=v_j.hop+ 1, then proceed to broadcast Packet (v_i.hop) packet, the node being continued until in network arrives the hop count of Sink node, Hop=k node is named as k node layers, wherein k is the integer more than or equal to 1, and k node layers only need to preserve hop information, Without preserving any information on adjacent Hierarchy nodes.

3. the method for data capture based on constructive interference in described asynchronous low duty ratio WSN according to claim 2, it is special Levy and be：In network initialization procedure, the sensor node need to be only carried out after the completion of a hierarchy selection, netinit, Sensor node carries out sleep scheduling according to LPP mechanism.

4. the method for data capture based on constructive interference in described asynchronous low duty ratio WSN according to claim 2, it is special Levy and be：When k layers of Source nodes have data to need transmission, Source nodes can intercept network channel for a period of time, etc. Treat that neighbor node revival sends probe packets to set up connection, set up after connection, adjacent node receives Source nodes and sent Awake packets to extend the recovery time of neighbor node；The Source nodes send awake packets and most arrived at last Sink node, Sink node is received after awake packets, by T_backoffAfter stand-by period, Sink node sends feedback Wrap Source nodes, T_backoffStand-by period ensures all probe packets transmitted and awake packet distances The Sink node that Sink is at least in double bounce, network can be handled when receiving awake bags according to following three kinds of situations：

Situation 41：The node of k=(k >=hop) layer will directly abandon and enter sleep state, it is to avoid the section of k=(k >=hop) layer Point participates in this concurrent transmission, to reduce network energy consumption；

Situation 42：K-1 layers of neighbor node can add hop (k-1) information of oneself when carrying out the forwarding of awake packets；K= (k>Hop (k-1)) layer neighbor node receive and sleep state directly abandoned and entered after awake packets；K-2 node layers are being received Awake packets, can use hop (k-2) covering hop (k-1) before forwarding, and k-2 node layers are continued executing with to be saved with hop (k-1) Point same operation；

Situation 43：Awake packets have been treated, and have kept the forward node of revival, the awake not sent by upper layer node The influence of bag.

5. the method for data capture based on constructive interference in described asynchronous low duty ratio WSN according to claim 4, it is special Levy and be：The Sink node is after awake packets are received, it will send feedback packets to Source nodes, The forward node that Source nodes receive feedback packets can be handled according to following three kinds of situations：

Situation 51：Source nodes receive feedback packets, but do not receive awake packets, and Source nodes will Feedback packets are abandoned, into sleep state；

Situation 52：The forward node of k=(k >=hop) level will directly abandon feedback bags, into sleep state；

Situation 53：Forward node in identical level, the feedback data of last layer minor node transmission will be received simultaneously Data are copied directly to be transmitted in transmit queue by bag, forward node from receiving queue without any processing, finally Concurrent transmission is reached Source nodes, and the generation constructive interference at Source nodes by feedback packets.

6. the method for data capture based on constructive interference in described asynchronous low duty ratio WSN according to claim 4, it is special Levy and be：By T_backoffAfter stand-by period, the Sink node sends feedback bags to Source nodes, works as feedback Packet is reached after Source nodes, and Source nodes are in T_waitAfter stand-by period, initiation interval time is T_countIt is concurrent Transmission, what is now transmitted is the data data packets that sensor node is collected；The forward node of identical level is received simultaneously To after data packets, fixed stand-by period T is had before the packet is sent_process, therefore meet the condition of constructive interference, Now the forward node on Source nodes to the path of Sink node will not initiate probe packets or awake packets, because This meets T_wait<T_backoff；

Source nodes start after concurrent transmission, if in 2 × T_processK=(hop-1) node layer is not listened to afterwards to turn Packet is sent out, then is retransmitted, to increase the reliability of transmission；If listening to and also having data Source in buffer queue Node can be in T_count=2 × T_processContinue to send data.

7. the method for data capture based on constructive interference in described asynchronous low duty ratio WSN according to claim 1, it is special Levy and be：After concurrent transmission is finished, forward node returns to LPP sleep scheduling states, after the data transfer is complete, by implicit Forward node in termination mode or display termination mode notification transmission path has completed transmission, then into sleep state, hereafter, Forward node will carry out dormancy dispatching according to LPP.

8. the method for data capture based on constructive interference in described asynchronous low duty ratio WSN according to claim 7, it is special Levy and be：In the implicit termination mode, the forward node for participating in concurrent transmission obtains the number of packet from awake bags Amount, forward node enters sleep after last packet has been forwarded；In the display termination mode, Sink node is received To after all count packets, confirmation ACK can be sent, NACK NACK is otherwise sent, the forwarding of concurrent transmission is participated in Node will terminate the concurrent transmission stage into sleep after ACK or NACK has been forwarded.