Lifetime Benefits through Load Balancing in Homogeneous Sensor Networks

In routing protocols for wireless sensor networks energy efficiency is of paramount importance. Reliability-oriented protocols discard lossy links to avoid the significant energy cost of packet loss. The downside is that nodes with a particularly favorable channel tend to be overused: their lifespan is curtailed and the total amount of data delivered by the network may be significantly reduced. This problem is particularly critical for the nodes that provide access to the sink, since they have to carry the weight of the whole network. The use of load balancing schemes can be expected to provide significant lifetime benefits: rather than always using the nodes with the best channel, traffic is redistributed over a larger number of relays. We quantify the benefits of load balancing by comparing a routing protocol with embedded load balancing to a reliability-oriented protocol. We present and interpret experimental evidence of the benefits that stem from load balancing, but at the same time we also show that there are situations in which load balancing does not help.