An adaptive hybrid routing method based on OLSR protocol

Abstract

The present application relates to the field of wireless communication, in particular to a kind of adaptive hybrid routing method based on OLSR protocol.The present application process includes: generating shortest path routing table and best link quality routing table;Shortest path routing table, using the principle of the total number of source node to destination node hop, from numerous routing paths, select optimal routing;Best link quality routing table, using the principle of the overall quality of link, from multiple routing paths, select optimal routing.When user initiates service request, using destination node address to query shortest path routing table and best link quality routing table, obtain the routing tuple reaching destination node.Then according to current service type and routing selection strategy, select the optimal routing type used, obtain next hop node address.The present application can select optimal routing using adaptive routing selection strategy according to the quality of service of different services and current wireless environment, to guarantee service quality of service, effectively improve user experience.

Description

Technical Field

[0001] This invention relates to the field of wireless communication, and in particular to an adaptive hybrid routing method based on the OLSR protocol. Background Technology

[0002] A wireless ad hoc network is a decentralized, self-organizing wireless network where each node is independent and discovers each other. Compared to wired ad hoc networks, wireless ad hoc networks differ primarily in the following aspects:

[0003] Channel interference is complex. Wireless nodes communicate via radio waves, and due to the complex electromagnetic environment of the air interface, wireless channels are highly susceptible to interference, and the link quality between nodes is prone to fluctuations.

[0004] The types of services are diverse. Wireless ad hoc networks are highly customizable. In order to meet the different services of different users, the network needs to provide different services, such as latency-sensitive services, bandwidth-sensitive services, etc.

[0005] Frequent node movement is a significant factor. Wireless ad hoc networks are characterized by mobility, allowing nodes to move freely in space. While this provides convenience for users, it also increases the complexity of network management. Frequent node movement leads to frequent changes in network topology, which in turn results in routing changes.

[0006] Based on the network characteristics analyzed above, an OLSR (Optimized Link State Routing) routing protocol can be used in wireless ad hoc networks. To obtain network-wide routing and topology information, the OLSR protocol requires each node to periodically send OLSR control messages, including HELLO and TC messages. Periodically sending HELLO messages allows the node to obtain the link status of neighboring nodes. Periodically sending TC messages allows the node to obtain the network topology. Through this process, nodes can obtain network-wide routing and topology information, thereby achieving the goal of routing-level networking.

[0007] The OLSR routing protocol only supports shortest path routing, and OLSR version 2 only supports best link quality routing. Considering the node mobility, channel complexity, and service diversity of ad hoc networks, using a single routing type is flawed and cannot meet the network requirements of different services.

[0008] The drawback of using a single shortest path route is that... Figure 2Using a network topology as an example, the numbers on the lines connecting nodes in the diagram represent link quality; the smaller the number, the higher the quality. In the diagram, node 1 needs to send data to node 3. According to the shortest path principle, node 1 will choose the path "Node 1 - Node 2 - Node 3". However, due to the poor link quality between nodes 2 and 3, the bandwidth of this link is limited. Meanwhile, the path "Node 1 - Node 5 - Node 4 - Node 3", although not the shortest path, has better link quality and can provide greater bandwidth. Choosing the shortest path with less bandwidth instead of the path with greater bandwidth is unacceptable for bandwidth-sensitive services.

[0009] The drawbacks of using a single best link quality are that... Figure 4 Using a network topology as an example, the numbers on the lines connecting nodes in the diagram represent link quality; the smaller the value, the higher the quality. In the diagram, node 1 sends data to node 5. According to the best link quality principle, node 1 will choose the path "Node 1-Node 2-Node 3-Node 4-Node 5". However, considering that although the link quality between node 1 and node 5 is poor, the user can still transmit normally to node 5 through multiple retransmissions, the service latency of the path "Node 1-Node 5" will be shorter than the latency of the best link quality path "Node 1-Node 2-Node 3-Node 4-Node 5". Choosing the best link quality path with higher latency instead of the path with lower latency is unacceptable for latency-sensitive services.

[0010] Based on the above analysis, the single route generation and selection strategy provided by the OLSR protocol cannot adequately meet the increasingly complex user needs. Therefore, an adaptive hybrid routing method based on the OLSR protocol is required. Summary of the Invention

[0011] This invention addresses the problems of the OLSR protocol's single route generation and selection strategy and its incompatibility with service quality by proposing an adaptive hybrid routing method based on the OLSR protocol.

[0012] The technical solution adopted in this invention is as follows:

[0013] An adaptive hybrid routing method based on the OLSR protocol includes the following steps:

[0014] Step S1: Generate the shortest path routing table based on the minimum path principle; generate the best link quality routing table based on the best link quality principle; and save both routing tables to the local database.

[0015] Step S2: When a user initiates a service request, the shortest path routing table and the best link quality routing table in the database are queried using the destination node address to obtain the route tuple to reach the destination node;

[0016] Step S3: Select the optimal route type to use based on the current service type and routing strategy, and obtain the next-hop node address.

[0017] Furthermore, the specific process of step S3 is as follows:

[0018] Step S3-1: If only the shortest path route or the best link quality route is available, select the existing route; otherwise, proceed to step S3-2.

[0019] Step S3-2: If the current service type is a non-latency-sensitive service, select the best link quality route and the process ends; otherwise, proceed to step S3-3.

[0020] Step S3-3: Let the shortest path hop count to the destination node be H1 and the optimal link quality route hop count be H2. Make a judgment: if H2-H1<=ThreshHop, then select the optimal link quality route; otherwise, proceed to step S3-4; where ThreshHop is the hop count difference threshold.

[0021] Step S3-4: If the shortest path link quality M <= ThreshMetric, then select the shortest path route; otherwise, select the route with the best link quality. ThreshMetric is the link quality threshold.

[0022] The advantages of this invention compared to the prior art are:

[0023] (1) Ensure service quality for different services and improve user experience.

[0024] Wireless ad hoc networks are highly customizable, and with increasingly diverse user needs, a single type of routing table can no longer meet these varied requirements. This invention maintains two sets of routing tables simultaneously: one is a shortest path routing table generated based on the minimum hop count principle, and the other is an optimal link quality routing table generated based on the best link quality principle. This allows for adaptive routing strategies to select the optimal route based on the service quality of different services and the current wireless environment, ensuring service quality and effectively improving user experience.

[0025] (2) Adaptive routing strategy to ensure service quality

[0026] The present invention provides an adaptive routing method that automatically selects the route type based on information such as service type, current network channel quality, and relay hop count, without user intervention. It can achieve a guaranteed gain in service quality under complex wireless environments and dynamically changing network topologies.

[0027] (3) This invention does not add any new air interface signaling or extend the signaling fields. It is generated entirely using the OLSR routing protocol, thus avoiding an increase in network load. Attached Figure Description

[0028] Figure 1 This is a flowchart of the OLSR routing strategy of the present invention.

[0029] Figure 2 This is a schematic diagram of the link quality of node 1 in the topology of this invention.

[0030] Figure 3 This is a schematic diagram of the link quality of the two nodes in the topology of this invention.

[0031] Figure 4 This is a schematic diagram of the link quality of the 3-node topology of the present invention.

[0032] Figure 5 This is a schematic diagram comparing the average latency of service 1 in topology 1 of the present invention.

[0033] Figure 6 This is a schematic diagram comparing the average latency of service 1 in topology 2 of the present invention.

[0034] Figure 7 This is a schematic diagram comparing the average latency of service 1 in topology 3 of the present invention. Detailed Implementation

[0035] The invention will be further explained below with reference to the accompanying drawings.

[0036] The OLSR routing protocol provides the optimal route from the source node to the destination node. Based on different route generation principles, this invention proposes an adaptive hybrid routing method based on the OLSR protocol to generate a shortest path routing table and a best link quality routing table. The shortest path routing table selects the optimal route from numerous paths based on the principle of minimizing the total number of hops from the source node to the destination node. The best link quality routing table selects the optimal route from multiple paths based on the principle of maximizing overall link quality. For example, for latency-sensitive services, the route with the shortest transmission latency is preferred (transmission latency is obtained through a comprehensive evaluation of relay hop count and link quality); for reliability and throughput-sensitive services, the best link quality route is preferred. Wireless ad hoc networks are constrained by air interface channels, and air interface resources are very limited. Any protocol expansion or increase in air interface messages will consume more air interface resources, increase network load, and reduce network throughput. Specifically, the method includes the following steps:

[0037] Step S1: Generate the shortest path routing table based on the minimum path principle; generate the best link quality routing table based on the best link quality principle; and save both routing tables to the local database.

[0038] Specifically, the shortest path routing table generation involves the following steps:

[0039] Step S101: Select symmetric neighbors from the one-hop neighbor set and add them to the shortest path route set;

[0040] Step S102: Select a symmetric two-hop neighbor from the strict two-hop neighbor set. If only one-hop path exists to the two-hop neighbor, add it directly to the shortest path route set. Otherwise, select the path with the best link quality and add it to the shortest path route set. If the link quality is also the same, a path can be randomly selected and added to the shortest path route set.

[0041] Step S103: Traverse the node topology set, generate the shortest path route tuple for all reachable nodes, and add it to the shortest path route set.

[0042] Specifically, the generation of the optimal link quality routing table includes the following steps:

[0043] Step S111: Select a symmetric neighbor from the one-hop neighbor set. If the link has outgoing neighbor metrics, add it to the best link quality route set; otherwise, ignore the one-hop neighbor tuple.

[0044] Step S112: Select a symmetric two-hop neighbor from the strict two-hop neighbor set. If only one-hop path exists to the two-hop neighbor, add it directly to the best link quality route set. Otherwise, select the one with the best link quality and add it to the best link quality route set. If the link quality is also the same, a path can be randomly selected and added to the best link quality route set.

[0045] Step S113: Traverse the node topology set, generate the best link quality route tuple for all reachable nodes, and add it to the best link quality route set.

[0046] Step S2: When a user initiates a service request, the shortest path routing table and the best link quality routing table in the database are queried using the destination node address to obtain the route tuple to reach the destination node;

[0047] Step S3: Select the optimal route type based on the current service type and routing strategy, and obtain the next-hop node address. For example... Figure 1 As shown, the specific process is as follows:

[0048] Step S3-1: If only the shortest path route or the best link quality route is available, select the existing route; otherwise, proceed to step S3-2.

[0049] Step S3-2: If the current service type is a non-latency-sensitive service, select the best link quality route and the process ends; otherwise, proceed to step S3-3.

[0050] Step S3-3: Let the shortest path hop count to the destination node be H1 and the optimal link quality route hop count be H2. Make a judgment: if H2-H1<=ThreshHop, then select the optimal link quality route; otherwise, proceed to step S3-4; where ThreshHop is the hop count difference threshold.

[0051] Step S3-4: If the shortest path link quality M <= ThreshMetric, then select the shortest path route; otherwise, select the route with the best link quality. ThreshMetric is the link quality threshold.

[0052] Example 1

[0053] by Figure 2 Let's take an example to illustrate the two types of routing. Figure 2 In the topology diagram, the numbers in the arrows represent link quality; the smaller the value, the higher the quality.

[0054] Specifically, the route generation from node 1 to node 3 is explained. There are two paths from node 1 to node 3: the first is "Node 1-Node 2-Node 3" (2 hops, link quality 4), and the second is "Node 1-Node 5-Node 4-Node 3" (3 hops, link quality 3). Therefore, the shortest path from node 1 to node 3 is "Node 1-Node 2-Node 3", while the best link quality route is "Node 1-Node 5-Node 4-Node 3". Following this method, the final shortest path routing table stored by node 1 is as follows:

[0055]

[0056] Similarly, the optimal link quality routing table stored in the final node 1 is as follows:

[0057]

[0058]

[0059] Example 2

[0060] by Figure 3 Let's take an example to illustrate the two types of routing. Figure 3In the topology diagram, the numbers in the arrows represent link quality; the smaller the value, the higher the quality. There are two paths from node 1 to node 5: the first is "Node 1 - Node 5" (1 hop count, link quality 5), and the second is "Node 1 - Node 2 - Node 4 - Node 5" (3 hop count, link quality 3). Therefore, the shortest path from node 1 to node 5 is "Node 1 - Node 5," while the optimal link quality route is "Node 1 - Node 2 - Node 4 - Node 5." Following this method of route generation, the final shortest path routing table stored on node 1 is as follows:

[0061]

[0062] Similarly, the optimal link quality routing table stored in the final node 1 is as follows:

[0063]

[0064] Example 3

[0065] Example 3 is a preferred example of Example 1.

[0066] Network Topology Reference Figure 2 As shown, if node 1 initiates service 1 (e.g., a PING service) to node 3, and the service is defined as a latency-sensitive service, the routing steps are as follows:

[0067] Step S1: Perform a routing table lookup using the address of destination node 3.

[0068] Step S2: Query the shortest path route and obtain the route tuple to the destination node 3.

[0069]

[0070] Step S3: Query the best link quality route and obtain the route tuple to the destination node 3.

[0071]

[0072] Step S4: Determine the optimal route type to use based on the current service type (latency-sensitive service) and the routing selection strategy, and obtain the next-hop node address.

[0073] Specifically, routing is performed according to the routing policy.

[0074] Step S4-1: The current route includes the shortest path route and the best link quality route, which requires further judgment.

[0075] Step S4-2: The current service is a latency-sensitive service, and further judgment is required.

[0076] Step S4-3: The shortest path route hop count to the destination node is H1=2, the optimal link quality route hop count is H2=3, calculate H2-H1=1, the result is equal to ThreshHop (hop count difference threshold, set to 1 here), select the optimal link quality route, and thus obtain the next hop address as node 5.

[0077] Example 4

[0078] Example 4 is a preferred example of Example 2.

[0079] Network Topology Reference Figure 3 As shown, if node 1 initiates service 1 (e.g., a PING service) to node 5, and the service is defined as a latency-sensitive service, the routing steps are as follows:

[0080] Step S1: Perform a routing table lookup using the address of destination node 5.

[0081] Step S2: Query the shortest path route and obtain the route tuple to the destination node 5.

[0082]

[0083]

[0084] Step S3: Query the best link quality route and obtain the route tuple to the destination node 5.

[0085]

[0086] Step S4: Determine the optimal route type to use based on the current service type (latency-sensitive service) and the routing selection strategy, and obtain the next-hop node address.

[0087] Specifically, routing is performed according to the routing policy.

[0088] Step S4-1: The current route includes the shortest path route and the best link quality route, which requires further judgment.

[0089] Step S4-2: The current service is a latency-sensitive service, and further judgment is required.

[0090] Step S4-3: The shortest path hop count to the destination node is H1 = 1, the best link quality hop count is H2 = 3, calculate H2 - H1 = 2, the result is greater than ThreshHop (hop count difference threshold, set to 1 here), further judgment is needed.

[0091] Step S44: The shortest path link quality M = 3, which is less than ThreshMetric (link quality threshold, set to 5 here). Select the shortest path route, and the next hop address is node 5.

[0092] Example 5

[0093] To confirm the hop count difference threshold and link quality threshold, this method uses simulation to determine them. Specifically, the same service is initiated using both the optimal path route and the optimal link quality route, with different link qualities set for the shortest path links, and the service latency is compared. Link quality is measured using packet loss rate, which is equal to packet loss rate multiplied by 100 and rounded up, i.e., Link Quality = CEIL(Packet Loss Rate * 100).

[0094] Topology 1: Reference Figure 2 Node 1 initiates a service, selecting the shortest path route and the best link quality route from Node 1 to Node 3 respectively. The hop count difference between the two routes is 1 hop. The service is executed 100 times, and the relevant latency and latency difference are calculated. Latency difference = latency of best link quality route - latency of shortest path route.

[0095] Topology 2: Reference Figure 3 Node 1 initiates a service, selecting the shortest path route and the best link quality route from Node 1 to Node 5 respectively. The hop count difference between the two routes is 2 hops. The service is executed 100 times, and the relevant latency and latency difference are calculated. Latency difference = latency of best link quality route - latency of shortest path route.

[0096] Topology 3: Reference Figure 4 Node 1 initiates a service, selecting the shortest path route and the best link quality route from Node 1 to Node 5 respectively. The hop count difference between the two routes is 3 hops. The service is executed 100 times, and the relevant latency and latency difference are calculated. Latency difference = latency of best link quality route - latency of shortest path route.

[0097] Statistical results are as follows Figure 5 , Figure 6 , Figure 7 As shown in the analysis, when the difference between the optimal link quality and the shortest path hop count is 1 hop, choosing the shortest path does not offer a significant advantage within a certain link quality range. As the hop count between the two paths gradually increases, choosing the shortest path offers a substantial delay advantage within a certain link quality range. However, as the link quality of the shortest path deteriorates, the delay advantage of the optimal link quality route gradually becomes apparent. Based on the simulation results, suitable hop count difference thresholds and link quality thresholds can be determined for this network. For example, in this embodiment, the simulation yields a hop count difference threshold of 1 and a link quality threshold of 5.

Claims

1. An adaptive hybrid routing method based on the OLSR protocol, characterized in that, It includes the following steps: Step S1: Generate the shortest path routing table based on the minimum path principle; generate the best link quality routing table based on the best link quality principle; and save both routing tables to the local database. Step S2: When a user initiates a service request, the shortest path routing table and the best link quality routing table in the database are queried using the destination node address to obtain the route tuple to reach the destination node; Step S3: Select the optimal route type to use based on the current service type and routing strategy, and obtain the next-hop node address; The specific process of step S3 is as follows: Step S3-1: If only the shortest path route or the best link quality route is available, select the existing route; otherwise, proceed to step S3-2. Step S3-2: If the current service type is a non-latency-sensitive service, select the best link quality route and the process ends; otherwise, proceed to step S3-3. Step S3-3: Let the shortest path hop count to the destination node be H1 and the optimal link quality route hop count be H2. Make a judgment: if H2-H1 <= ThreshHop, then select the optimal link quality route; otherwise, proceed to step S3-4; where ThreshHop is the hop count difference threshold. Step S3-4: If the shortest path link quality M <= ThreshMetric, then select the shortest path route; otherwise, select the route with the best link quality. ThreshMetric is the link quality threshold.

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