Latency Trade-off of Particle Swarm Optimization- enabled Seamless Handoff in Mobile WSNs

Mobility in wireless sensor networks may interrupt a link established between two nodes. Since most medium access control protocols do not accommodate mobility, a node has two options to tackle a deteriorating link: (option A) to maintain data transmission until the connection breaks and then establish a new link with a new relay node; and (option B) to seamlessly transfer the communication to a more stable link in parallel to the data transmission over the existing link. To realize option B, this paper proposes a particle swarm optimization -enabled seamless handoff mechanism, which allows a sensor node to handle the transmission according to the decay in the quality of a link. To prove the optimization effect of the handoff, this paper designs a static receiver-triggered protocol, investigates the effect of mobility on the latency of the protocol, defines a criterion to initiate the handoff, estimates the real-time position of nodes by designing the particle swarm optimization method, and develops a mobility-oriented seamless handoff module on the static protocol. The latency for the transmission of a burst of data for both options is compared using NS2. The simulation result shows that the time demands to set up a new connection is larger than the time demands to handoff. The latency for a signal -hop communication when the handoff is used can be reduced by 42.42% at the lowest compared with the case when it is not used. This number can even be greater as the duty cycle, the number of hops between nodes, and the network density increase.