MAC energy performance in duty cycle constrained sensor network and effect of sleep

Recently, energy efficiency has become a topic of great interest in sensor networks. Low frequency radio solutions in the ISM bands have been found attractive, because of their relatively easy implementation. However, these low frequency ISM bands are restricted by a duty cycle in most of the countries in the world to usually 10% or 1% of the active time. Also, because the data rates of commercial radios are relatively low, the transmittable frame sizes are limited to few tens of octets. The combination of low duty cycle and small data frames can prove to be disastrous for many otherwise well performing MAC protocols in the energy consumption perspective. In this paper, an energy consumption model for transmission and reception is proposed, a general analysis of the constraints imposed by duty cycle are presented, and the method is used to predict the worst-case scenario energy performance of our nanoMAC protocol and nonpersistent CSMA. From the analysis we can conclude that nanoMAC has considerably better characteristics for duty cycle constrained operation than nonpersistent CSMA.