Throughput of Power-limited Wireless Networks with Processing Energy Considerations

It is widely believed that "whispering to the nearest neighbor" (ie. taking a large number of short hops) is the throughput optimal routing scheme for all ad-hoc wireless networks. We show that for power-limited networks where processing energy is not an insignificant factor, instead of taking short hops, there exists a characteristic hop distance that, along with load balancing, can attain high throughput, even for networks with a small number of nodes. In fact, the "whisper to the nearest neighbor" routing scheme leads to strictly suboptimal uniform throughput on the order of O(root lnN/N) when processing energy is considered. We show that taking Theta(1) number of hops is throughput, energy, and delay optimal, achieving Theta(1) uniform capacity under uniform traffic. These results are contrary to previous results on the capacity of power-limited wireless networks under a zero-processing energy assumption, which showed that capacity increases with increasing number of nodes. Hence, failing to account for processing energy not only leads to suboptimal routing schemes, but also leads to inflated optimism about the capacity scaling behavior of power-limited wireless networks.