# Beacon-Based Hybrid Routing Protocol for Large-Scale Unmanned Vehicle Ad Hoc Network
## 2 Beacon-Based Multi-Agent Network Hybrid Routing Algorithm
### Path Discovery and Maintenance
#### 2.2.1 Path Discovery
The source node and destination node would actively respond to the pulse message broadcast by the beacon node to ensure the real-time validity of the communication link. The non-source node and destination node would not respond to the pulse message to reduce the route cost. ### Beacon-Based Hybrid Routing Protocol

In active DSDV, the cost of maintaining N paths per node is \(O\)_(N)_. The maintenance cost of each link is \(O\)_(N/T)_, where \(N\) is the number of nodes and \(T\) is the lifetime of a link. Therefore, the total cost of maintaining links for N nodes in the network is \(O\)_(N\({}^{2}\)/T)_. In on-demand routing protocols, such as AODV and dynamic source routing (DSR), the routing cost is reduced by maintaining active links on demand; the cost of maintaining active links for N nodes is \(O\)_(NF)_, where \(F\) is the number of active links on each node. However, the on-demand routing protocol still uses the method of flooding in the process of path transmission, and the broadcast cost of node flooding is \(O\)_(N)_. Therefore, the total number of maintenance links of \(N\) nodes in the network is \(O\)_(FN\({}^{2}\)/T)_. The beacon-based hybrid routing protocol uses single path tree to discover and maintain links; only the beacon node in the network periodically send a flooding. Therefore, the maintenance cost of the link is \(O\)_(N/T)_, and \(T\) is the pulse period of the beacon-based protocol. In active and on-demand routing protocols, when the number of nodes increases in a large scale, the cost of routing protocols increases exponentially, which is not suitable for large-scale networking scenarios. The beacon-based routing protocol uses the single path tree method to effectively solve the problem of flooding in the network. The routing cost and the number of nodes increase linearly, which reduces the cost of network maintenance. ## 3 Results

### Simulation Environment

The NS3 simulation platform was used to build a dynamic simulation environment of service data to evaluate the routing protocol we designed. The MAC layer in the NS3 simulation environment uses the IEEE802.11 standard. Table 1 shows the basic simulation parameters. Table 2 shows the beacon-based hybrid routing protocol parameters. In this simulation, in order to verify the performance of multi-node concurrent network communication, the node access time is limited. The node access time is required to be randomly selected between simulation start time (communication start time/s) and active link data. That is, the network access time in this experiment was between 80 s + 5 s \(\sim\) 50 s, so that it can guarantee concurrent communication with multiple links at the same time in the active link time. According to the above simulation parameters, 50 nodes were randomly distributed in the simulation environment with a range of 1000 m \(\times\) 1000 m, moving randomly at the speed of 5 m/s, and 5 to 50 groups of active communication links were randomly generated in the network. AODV and DSDV were selected as comparisons to the proposed beacon-based routing protocol. The performance of the routing protocol was estimated by comparing the simulation results. ### Results and Analysis

This paper mainly compared and analyzed the packet delivery rate and routing load. In order to ensure the randomness of node positions during the test, the nodes were in the stage of random movement before the 80 s of simulation, then communication links were established randomly from the 80 s to 170 s, in which the number of active links varied from 5 to 50. The results are discussed as follows. (1) Packet Delivery Rate (PDR)

PDR is the ratio of packets received by the target node to packets sent by the source node. It is a statistical measure of correctly transmitted packets. This index mainly examines the reliability and communication quality of the network. The higher the successful packet delivery rate, the higher the network reliability and the better the communication quality.