GLOBAL: A Gradient-based routing protocol for load-balancing in large-scale wireless sensor networks with multiple sinks

Recently, multi-sink wireless sensor networks (WSNs) are envisioned to solve the hot spot problem caused by traditional single-sink WSNs. Routing protocols should be able to distribute network traffic evenly to multiple sinks to prolong network lifetime and they should be scalable. Gradient-based routing protocols are known to be suitable for the networks, where each node maintains its gradient representing the direction toward a neighbor node to reach a sink. In particular, existing protocols allow a sensor node to construct its gradient using the cumulative traffic load of a path for load-balancing. However, they have a critical drawback that a sensor node cannot efficiently avoid using the path with the most overloaded node. Hence, this paper introduces a new gradient-based routing protocol for load-balancing (GLOBAL) with a new gradient model to maximize network lifetime. In GLOBAL, the least-loaded path which also avoids the most overloaded sensor node is selected for forwarding. Through ns-2 simulation, we verify that GLOBAL achieves better performance than the shortest path routing protocol and load-aware gradient-based routing one.