Non-uniform Entropy Compression for Uniform Energy Distribution in Wireless Sensor Networks

Recently there has been an influx of work on extending a wireless sensor networks lifetime by distributing source compression and deploying non-homogeneous nodes to handle the aggregation. Both of these mechanisms have been shown to increase the network´s lifetime, but they each have requirements that might not be plausible. With distributed source compression, message distributions must be known a-priori, and the existing practical schemes tend to require modification of a layer in the network stack. In non-homogeneous node deployment, placement of more powerful nodes is a major factor in balancing network energy, but many scenarios exist where this is not reasonable. We propose non-uniform entropy compression wherein bottleneck nodes trade computation energy for transmission energy and do more aggressive compression, which induces a synthetic nonhomogeneity across a network built from physically identical nodes and extends network lifetime. Our method inserts a compression layer between medium access control (MAC) and the routing layers without modifying existing network layers, thus providing a general platform for message compression. We performed extensive simulations to show how our architecture affects network energy and delay considering message size, queue size, compression ratio and time, and network topology. Our simulations show that a computationally inexpensive and effective compression algorithm (with high compression ratio) that takes less than 0.2 s/ kbytes time (including both compression and decompression time) to execute will help extend network lifetime for most motes; for some motes (such as Mica2 and Rene2) 1 s/kbytes or more will work also. This supports our theory that synthetic-non-homogeneity is a viable and practical method for extending wireless sensor networks(WSNs) lifetime.