An analysis of the lifetime of OLSR networks

The Optimized Link State Routing (OLSR) protocol is a well-known route discovery protocol for ad-hoc networks. OLSR optimizes the flooding of link state information through the network using multipoint relays (MPRs). Only nodes selected as MPRs are responsible for forwarding control traffic. Many research papers aim to optimize the selection of MPRs with a specific purpose in mind: e.g., to minimize their number, to keep paths with high Quality of Service or to maximize the network lifetime (the time until the first node runs out of energy). In such analyzes often the effects of the network structure on the MPR selection are not taken into account. In this paper we show that the structure of the network can have a large impact on the MPR selection. In highly regular structures (such as grids) there is even no variation in the MPR sets that result from various MPR selection mechanisms. Furthermore, we study the influence of the network structure on the network lifetime problem in a setting where at regular intervals messages are broadcasted using MPRs. We introduce the ’maximum forcedness ratio’, as a key parameter of the network to describe how much variation there is in the lifetime results of various MPR selection heuristics. Although we focus our attention to OLSR, being a widely implemented protocol, on a more abstract level our results describe the structure of connected sets dominating the 2-hop neighborhood of a node

Coverage Issues in Wireless Ad-Hoc Sensor Networks

Wireless Ad-Hoc sensor networks have a broad range of applications in the military,vigilance, environment monitoring, and healthcare fields. Coverage of the sensor networks describes how well an area is monitored. The coverage problem has been studied extensively, especially when combined with connectivity and well-organized. Coverage is a typical problem in the wireless sensor networks to fulfil issued sensing tasks. In general, sensing analysis represents how well an area is monitored by sensors. The quality of the sensor network can be reflected by levels of coverage and connectivity that it offers. The coverage issues have been studied extensively, especially when combined with connectivity and energy efficiency. Constructing a connected fully covered, and energy efficient sensor network is valuable for real world applications due to limited resources of sensor nodes. The survey recent contributions addressing energy efficient coverage problems in the context of static WASNs, networks in which sensor nodes do not move once they are deployed and present in some detail of the algorithms, assumptions, and results. A comprehensive comparison among these approaches is given from perspective of design objectives, assumptions, algorithm attributes and related results