Performance of seamless soft handoff protocol for tactic mobile ad hoc networks

In this paper, we present two loop free alternative path (LFAP) computation algorithms for the seamless soft handoff (SHO) architecture proposed in [5] and its performance for tactical wireless mobile ad hoc networks. The proposed handoff architecture consists of several key components such as LFAP computation module, link quality prediction module, and link monitoring module. The key idea of the seamless soft handoff protocol is to proactively switch to a pre-stored alternative path, based on the interactions among SHO modules, before a potential node/link failure occurs. The prediction module predicts the link quality in the near future and triggers an alarm if the link quality predicted would be below a certain threshold. Based on the information from the monitoring module and the prediction module, each node makes a decision whether to switch to a pre-stored path, which is computed through the LFAP computation module. Results from simulation in OPNET show that the LFAP coverage of SHO increases considerably compared with several protocols proposed by the IETF IP fast-reroute (IPFRR) working group. The system throughput under SHO is also compared with that under OSPF. Simulation results show that, for the scenarios considered, the system throughput under SHO remains the same while the throughput under OSPF dropped significantly during the period when a node or link fails (for example, due to mobility events).