Multi-tier Grid Routing to Mobile Sink in Large-scale Wireless Sensor Networks

Improving the efficiency of data dissemination algorithms and protocols to mobile sink remains as an interesting research and engineering issue, especial for large-scale wireless sensor network. As the node energy and resources are limited, theses protocols should meet energyefficiency, low delay and high delivery ratio requirements. Although an energy-efficient dissemination tree (d-tree) can be constructed with sink mobility, the delayed handoff could lead to suboptimal routing trees for a substantial amount of time as the network grows larger, and also the efficiency heavily relied on the location of the sink, thus it may offset the load balance resulting from hierarchical tree structure. In this paper, we propose an energy efficient routing protocol MGRP (Multi-tier Grid Routing Protocol) which introduces a special hybrid multi-tier structure for data dissemination. MGRP divides the observation areas into square grids, could be different size. Within each grid, we form an optimized cluster which transmits reliable data to its higher tier cluster head, the uppermost cluster head from neighbor grids further negotiate to construct the data d-tree from which the mobile sink can access and send query. Through intensive simulation in a given mobile sink experiment, MGRP performs better in terms of energy consumption and average delay respectively compared to previous protocols such as TTDD (grid-based), SEAD (treebased) and COSEN (chain-based), under practical conditions, where sensors may die out, but with initial large