Energy-optimum Throughput and Carrier Sensing Rate in CSMA-based Wireless Networks
A model for the energy consumption of a node as a function of its throughput in a wireless CSMA network is proposed. A single-hop network is modeled, and then a multi-hop network. The operating the CSMA network at a high throughput is energy inefficient since unsuccessful carrier sensing attempts increase the energy consumption per transmitted bit. Operating the network at a low throughput also causes energy inefficiency because of increased sleeping duration. Achieving a balance between these two opposite operating regimes, derive the energy-optimum carrier-sensing rate and the energy optimum throughput which maximize the number of transmitted bits for a given energy budget. For the single-hop case, it is shown that the energy-optimum total throughput increases as the number of nodes sharing the channel increases. For the multi-hop case, it is shown that energy-optimum throughput decreases as the degree of the conflict graph corresponding to the network increases. For both cases, the energy-optimum throughput reduces as the power required for carrier-sensing increases. The energy-optimum throughput is also shown to be substantially lower than the maximum throughput and the gap increases as the degree of the conflict graph increases for multi-hop networks.