Geographic forwarding and adaptive load balancing in wireless sensor networks

In the future sensor nodes will either have GPS capabilities, or be able to run localization protocols in order to get an accurate estimation of their position. These features would make geographic convergecasting a feasible and promising solution for WSNs. Key for the actual implementation of WSNs is the design of cross-layer solutions which consider explicitly the resource constraints of sensor nodes, especially in terms of available energy, limited memory and processing capabilities. We present a new protocol, named ALBA (Adaptive-Load Balanced Algorithm), which uses a cross-layer approach, pursuing the following goals: i) ALBA minimizes the number of hops required to reach the sink through a geographic forwarding scheme; ii) traffic is distributed evenly in the network, favoring nodes that are experiencing low congestion, while avoiding overloaded regions; iii) channel access efficiency is optimized through an adaptive back-to-back transmission of "bursts of packets" once a relay is selected, and iv) nodes are progressively made aware of routes to redirect the packets to the sink even when a connectivity hole occurs, i.e., when some nodes are not able to deliver packets to the sink because of lack of next-hop relay nodes closer to the sink.