Summary

Wireless sensor networks must be designed to meet a number of challenging requirements including extended lifetime in the face of energy constraints, robustness, scalability, and autonomous operation. The many design concepts and protocols described in the preceding chapters address these challenges in different aspects of network operation. While much additional work remains to be done to realize the potential of tomorrow's systems, even these partial solutions offer reason for optimism.

Perhaps the most important lesson to take away from the studies described in this book is that the fundamental challenges must be tackled by making appropriate design choices and optimizations across multiple layers.

Consider energy efficiency, which is perhaps the most fundamental concern due to limited battery resources. The most significant source of energy consumption in many applications is radio communication. At deployment time, energy efficiency concerns can inform the selection of an appropriate mixture of heterogeneous nodes and their placement. Localization and synchronization techniques can be performed with low communication overheads for energy efficiency. At the physical/link layers, parameters such as the choice of modulation scheme, transmit power settings, packet size, and error control techniques can provide energy savings. Medium access techniques for sensor networks use sleep modes to minimize idle radio energy consumption. Topology control techniques suitable for over-deployed networks also put redundant nodes to sleep until they are needed to provide coverage and connectivity. At the network layer, routing techniques can be designed to incorporate energy-awareness and innetwork compression to minimize energy usage.