An adaptive distributed routing method for linear wireless sensor network

Abstract

The application belongs to the field of industrial wireless sensor network, and particularly relates to a self-adaptive distributed routing method for linear wireless sensor network, which comprises the following steps: designing a distributed routing method based on opportunistic routing, performing priority selection on a plurality of alternative nodes to forward data, so as to improve the network fault tolerance and path recovery capability; utilizing the broadcast characteristics of wireless signals to forward data packets to a group of alternative nodes, so as to avoid excessive dependence on one or several fixed forwarding nodes, and improve the transmission reliability of the network and the balance of energy consumption; and the process of selecting a forwarding node occurs at the node end, so that the distributed routing method does not depend on the collection of network information and the perception of topology information, and avoids the interaction of additional control messages.

Description

Technical Field

[0001] This invention belongs to the field of industrial wireless sensor networks, specifically relating to an adaptive distributed routing method for linear wireless sensor networks. Background Technology

[0002] Wireless sensor networks exhibit flexible and varied network topologies. Linear topologies are primarily used in scenarios such as railway and highway patrols, gas and oil pipeline monitoring, and subway tunnels. In environments like subway tunnels and pipeline monitoring, sensor nodes face more severe channel conditions due to multipath fading and other factors. Furthermore, node deployment can extend for several kilometers, making node maintenance and replacement complex and costly. Failures of some nodes, especially specific fixed relay nodes, can lead to network fragmentation, potentially blocking data from all nodes downstream of the failed node, or even causing network "death." Therefore, improving the reliability of node communication and reducing reliance on specific relay nodes is crucial for the stability and lifespan of linear topology networks.

[0003] Current research on routing mechanisms is mostly based on two-dimensional networks, with very little research on routing mechanisms for linear topology networks. Compared to two-dimensional networks, linear networks have only one transmission path, making them more susceptible to node failures and causing the network to be fragmented into multiple disconnected segments. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an adaptive distributed routing method for linear wireless sensor networks, comprising:

[0005] S1: When constructing a linear topology network, all nodes maintain their hierarchical information. The root node's hierarchical level is fixed at the minimum value of 0. When a node joins the network, it obtains the hierarchical information of all nodes within its communication range {L}. min ,...,L max} and set its own hierarchy information to L min +1, where L min L represents the lowest level of information. max Indicates the highest level of information;

[0006] S2: The sending node sends data in a flooding manner, encapsulating the transmission direction and its own hierarchical information in the data packet. Nodes within its communication range receive the data and, based on the transmission direction and whether the minimum forwarding energy consumption E is met, determine whether to forward the data. min The packet loss rate Q requires selecting the set of repeaters {N1, N2, ..., N}. m In the repeater set, all nodes have a certain probability of becoming a repeater node, where N m This represents the m-th node within the communication range;

[0007] S3: All nodes within the repeater set obtain their relative distance d with the transmitting node based on the RSSI value of the received data. rssi Combined with the node's own remaining energy E re The priority parameter q is used to calculate the packet loss rate Q.

[0008] S4: After the repeater nodes have distributedly calculated their own priority q, they calculate the backoff delay t based on the priority. back_off The priority level determines the length of the backoff delay. Nodes with higher priority have lower delays and are easier to forward. Finally, to prevent conflicts caused by identical backoff times, a random variable X is added to adjust the backoff delay t. back_off Size in Between, among them, Indicates the maximum backoff delay;

[0009] S5: When the timer expires, the node will immediately forward the data packet. If the node whose timer has not expired hears that a node has already sent data, it will block its own timer and stop sending the data.

[0010] S6: After sending data, the sending node will continue to listen to the network. If no node forwards or responds to the data packet within the waiting time, the data will be retransmitted. If a node forwards or responds, the forwarding is considered successful.

[0011] The beneficial effects of this invention are:

[0012] This invention considers that linear wireless networks are more susceptible to node failures and designs a distributed routing mechanism based on opportunistic routing. This avoids network fragmentation caused by the failure of certain fixed forwarding nodes. By distributing the decision on whether to join the repeater set at the node end and considering the priority determination method under the influence of multiple factors such as transmission distance, node energy consumption, and packet loss rate, this invention overcomes the problem of linear topology networks having a single path and higher requirements for transmission reliability and stability. This ensures the network's adaptability to node failures and the overall reliability, stability, and lifespan of the network. Attached Figure Description

[0013] Figure 1 This is a flowchart of an adaptive distributed routing method for linear wireless sensor networks according to the present invention.

[0014] Figure 2 This is a comparison diagram of different routing methods for failed nodes in this invention;

[0015] Figure 3 This is a diagram illustrating the process of repeater set selection, delay backoff, and blocking timing in this invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] An adaptive distributed routing method for linear wireless sensor networks, such as Figure 1 This includes the following steps:

[0018] S1: When constructing a linear topology network, all nodes maintain their hierarchical information. The root node's hierarchical level is fixed at the minimum value of 0. When a node joins the network, it obtains the hierarchical information of all nodes within its communication range {L}. min ,...,L max} and set its own hierarchy information to L min +1;

[0019] In this invention embodiment, since there is only one transmission path in the linear topology network, data transmission is divided into uplink and downlink directions. Each receiving node makes forwarding decisions in a distributed manner without needing to know the status of other nodes. The network is hierarchical, with the root node's hierarchy initialized to 0. When a node joins the network, it obtains the hierarchy information of nodes within its communication range.

[0020] L k =min{L i ,...,L j +1

[0021] Where {L i ,...,L j The process involves collecting the network hierarchy of nearby nodes for each node and selecting the node to become the next level in the smallest network hierarchy. The network hierarchy increases progressively from the root node, with a maximum of L levels. i Each node of +2 can be connected to L i +1 must communicate with at least one node, but cannot communicate with level L. i Communication can occur between any of the nodes. The hierarchy is L. j The node sends downlink data only at level L. j With L j +1 nodes are added to the repeater set; uplink data only has L. j With L j Nodes at level -1 are added to the repeater set.

[0022] S2: The sending node sends data in a flooding manner, encapsulating the transmission direction and its own hierarchical information in the data packet. Nodes within its communication range receive the data and, based on the transmission direction and whether the minimum forwarding energy consumption E is met, determine whether to forward the data. minThe packet loss rate Q requires selecting the set of repeaters {N1, N2, ..., N}. m In the repeater set, all nodes have a certain probability of becoming a repeater node, where N m This represents the m-th node within the communication range;

[0023] S3: All nodes within the repeater set obtain their relative distance d with the transmitting node based on the radio signal strength index (RSSI) of the received data. rssi Combined with the node's own remaining energy E re The priority parameter q is used to calculate the packet loss rate Q.

[0024] In this example, multiple alternative nodes are selected for forwarding based on priority, without relying on specific relay nodes. This allows for rapid selection of other nodes when a node fails, improving network fault tolerance and routing path recovery capabilities. Figure 2 Both the line-by-line transmission scheme and the K-hop transmission scheme specified Node 4 and Node 5 as forwarding nodes before transmission. When a forwarding node fails or transmission fails, the transmission also fails. By using multiple alternative nodes for priority forwarding, Node 3 can naturally forward when Node 4 fails, without needing to send any control commands to switch forwarding nodes.

[0025] All nodes within the repeater set obtain their relative distance d with the transmitting node based on the RSSI value of the received data. rssi ,include:

[0026]

[0027] Where, d rssi R represents the relative distance between a node in the repeater set and the sending node. val The RSSI value represents the wireless signal strength of the received data. A represents the RSSI value when the distance between the transmitter and receiver is one meter. n represents the environmental attenuation factor. abs() represents the absolute value function.

[0028] Node N in the repeater set i The relative distance to the transmitting node is obtained based on the received signal strength (RSSI). To reduce the number of times data packets are transmitted in the network, the node furthest within the communication range is selected for forwarding each time. Simultaneously, considering network load balancing and node performance, the remaining energy E of the node is introduced. re Packet loss rate Q calculation priority parameter q:

[0029]

[0030] Among them, E limitThis is the minimum energy limit for a node to maintain network operation. If the remaining energy is below this minimum limit, the node's priority is set to the lowest. max This is to ensure that the node possesses the maximum energy. This represents the maximum distance at which a node can maintain stable communication, where κ is the distance factor coefficient and λ is the packet loss rate factor coefficient. Priority is primarily determined by relative distance during the initial operational phase of a node. rssi As node energy consumption increases, priority decreases, and other nodes with higher remaining energy gain higher priority, thus balancing overall network energy consumption and improving network lifetime. Because the RF performance of different nodes is affected by hardware and other factors, each node dynamically updates its packet loss rate Q with each transmission; an increase in the packet loss rate reduces priority.

[0031] S4: After the repeater nodes have distributedly calculated their own priority q, they calculate the backoff delay t based on the priority. back_off The priority level determines the length of the backoff delay; nodes with higher priority have lower delays and are easier to forward. Finally, to prevent conflicts caused by identical backoff times, a random variable X is added. between;

[0032] In this invention embodiment, node priority is calculated locally based on the RSSI value of the data received by the node and its own maintained energy consumption and packet loss rate. Different nodes convert different priorities into backoff delays t. back_off For delayed forwarding, nodes with higher priority have shorter delay times and are forwarded more quickly. Figure 3 As shown. The formula for calculating the backoff delay is:

[0033]

[0034] in, For maximum backoff delay, This is the minimum transmission time for a node to send data to the air interface. Multiple nodes sending data below this time interval may cause collisions. ΔN tx The maximum backoff time can be divided into the granularity of the minimum transmission interval, which is mainly determined by the transmission time of the node. The value range is [0, ΔN] tx ], and round down, X is Random numbers within the range.

[0035] S5: When the timer expires, the node will immediately forward the data packet. If the node whose timer has not expired hears that a node has already sent data, it will block its own timer and stop sending the data.

[0036] S6: After sending data, the sending node will continue to listen to the network. If no node forwards or responds to the data packet within the waiting time, the data will be retransmitted. If a node forwards or responds, the forwarding is considered successful.

[0037] In this example, as nodes of different priorities begin to roll back their delays, the first node to finish its delay forwards data and then blocks the delays of other nodes in the same set of forwarders, marking the completion of this forwarding operation. Figure 3 As shown. When the nodes in the repeater set begin to back off due to delay, the delay of higher-priority nodes will end earlier. Under normal working conditions, the highest-priority node will forward the data packet. At the same time, if a high-priority node fails, the low-priority node will also forward the data after its delay ends. Once a node in the same repeater set forwards data, it will block the delay of other nodes, and other nodes will no longer forward the data.

[0038] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An adaptive distributed routing method for linear wireless sensor networks, characterized in that, include: S1: When constructing a linear topology network, all nodes maintain their hierarchical information. The root node's hierarchical level is fixed at the minimum value of 0. When a node joins the network, it obtains the hierarchical information of all nodes within its communication range {L}. min ,...,L max } and set its own hierarchy information to L min +1, where L min L represents the lowest level of information. max Indicates the highest level of information; S2: The sending node sends data in a flooding manner, encapsulating the transmission direction and its own hierarchical information in the data packet. Nodes within its communication range receive the data and, based on the transmission direction and whether the minimum forwarding energy consumption E is met, determine whether to forward the data. min The packet loss rate Q requires selecting the set of repeaters {N1, N2, ..., N}. m In the repeater set, all nodes have a certain probability of becoming a repeater node, where N m This represents the m-th node within the communication range; S3: All nodes within the repeater set obtain their relative distance d with the transmitting node based on the RSSI value of the received data. rssi Combined with the node's own remaining energy E re The priority parameter q is used to calculate the packet loss rate Q. S4: After the repeater nodes have distributedly calculated their own priority q, they calculate the backoff delay t based on the priority. back_off The priority level determines the length of the backoff delay. Nodes with higher priority have lower delays and are easier to forward. Finally, to prevent conflicts caused by identical backoff times, a random variable X is added to adjust the backoff delay t. back_off Size in Between, among them, Indicates the maximum backoff delay; S5: When the timer expires, the node will immediately forward the data packet. If the node whose timer has not expired hears that a node has already sent data, it will block its own timer and stop sending the data. S6: After sending data, the sending node will continue to listen to the network. If no node forwards or responds to the data packet within the waiting time, the data will be retransmitted. If a node forwards or responds, the forwarding is considered successful.

2. The adaptive distributed routing method for linear wireless sensor networks according to claim 1, characterized in that, In steps S1-S2, the linear topology network has only one transmission path, and the data transmission is divided into two transmission directions: uplink and downlink. Each receiving node makes forwarding decisions in a distributed manner and does not need to know the status of other nodes. Linear topology networks are hierarchical. The root node's hierarchy is initialized to 0. When a node joins the network, it obtains the hierarchy information of nodes within its communication range. The node collects the network hierarchy of nearby nodes and selects to become the next layer below the smallest network hierarchy. The network hierarchy increases progressively from the root node, with a maximum of L layers. i Each node of +2 can be connected to L i +1 must communicate with at least one node, but cannot communicate with level L. i Communication between any two nodes; hierarchy is L j The node sends downlink data only at level L. j With L j The node with +1 is added to the repeater set, and the uplink data only contains L. j With L j Nodes at level -1 are added to the repeater set.

3. The adaptive distributed routing method for linear wireless sensor networks according to claim 1, characterized in that, All nodes within the repeater set obtain their relative distance d with the transmitting node based on the RSSI value of the received data. rssi ,include: Where, d rssi R represents the relative distance between a node in the repeater set and the sending node. val The RSSI value represents the wireless signal strength of the received data. A represents the RSSI value when the distance between the transmitter and receiver is one meter. n represents the environmental attenuation factor. abs() represents the absolute value function.

4. The adaptive distributed routing method for linear wireless sensor networks according to claim 1, characterized in that, All nodes within the repeater set obtain their relative distance d with the transmitting node based on the RSSI value of the received data. rssi Combined with the node's own remaining energy E re The priority parameter q for calculating the packet loss rate Q includes: Where q represents the priority parameter; E limit This indicates the minimum energy requirement for a node to maintain network operation; nodes with less remaining energy will have their priority set to the lowest. max This indicates the maximum energy a node can possess; κ represents the maximum distance at which a node can maintain stable communication; λ represents the distance factor coefficient; and λ represents the packet loss rate factor coefficient.

5. The adaptive distributed routing method for linear wireless sensor networks according to claim 1, characterized in that, Calculate the backoff delay t based on priority. back_off ,include: Among them, t back_off Indicates a rollback delay. Indicates the maximum backoff delay; This represents the minimum transmission time for a node to send data to the air interface. Multiple nodes sending data below this time interval may cause collisions; ΔN tx This indicates the granularity at which the maximum backoff time can be divided into the smallest transmission interval; q represents the priority parameter. The value range is [0, ΔN] tx [and round down; X represents a random variable, which is...] Random numbers within the range.

6. The adaptive distributed routing method for linear wireless sensor networks according to claim 1, characterized in that, In steps S3-S4, the nodes in the repeater set begin to back off due to delays. The higher the priority of the node, the earlier the delay ends. When the nodes are working normally, the highest priority node will forward the data packet. At the same time, if a high-priority node fails, the low-priority node will also forward the data packet after its delay ends. Once a node in the same repeater set forwards data, it will block the delay of other nodes, and other nodes will no longer forward the data.

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