Effect of Relay Nodes on End-to-End Delay in Multi-hop Wireless Ad-hoc Networks

Channel access delay in a wireless adhoc network is the major source of delay while considering the total end to-end delay. Channel access delays experienced by different relay nodes are different in multi-hop adhoc network scenario. These delays in multi-hop network are analysed in the literature assuming channel access delays are independent and are of same magnitude at all the nodes in the network. In this work, the end to-end delay in a multi-hop adhoc network is analysed taking into account the silent relay nodes. Along with silent relay node effect, Channel access probability (p), transmission radius (r) analogous to transmit power, network throughput and density of nodes arête other factors considered for the end-to-end delay analysis. Effect of network parameters along with silent relay nodes on end-to-end delay is found to be considerably high compared to the previous literature results. Given a bound on end-to-end delay with percentage of silent relay nodes, throughput, node density requirements for a multi-hop adhoc network, optimal ranges of transmission radius and channel access probability can be obtained from the proposed analysis. End-to-end delay increases with silent relay nodes along with transmission radius(r), channel access probability(p), node density and throughput. It is clear from the analysis, that the effect of silent relay nodes on end to-end delay cannot be ignored to maintain certain Quality of service (QoS) metrics for the multi-hop wireless adhoc network.

I. Introduction

Adhoc networks can communicate without fixed infrastructure. Ease and less time for deployment are the main advantages of adhoc networks. The adhoc networks are used in very diverse region of application from biological spheres to ubiquitous computing. Wireless sensor based adhoc networks have low bandwidth and more channel access delays. Delay is considered to be one of the main quality of service (QoS) metric for time constrained applications in adhoc networks. Wireless Sensor networks is one of major applications nowadays as they operate mostly in adhoc mode. Diverse delay requirements are required to support heterogeneous sensor network applications. Applications like detection of fire in forest, seismic activity need delay differentiation for best use of the measurements obtained by sensors.