Short Clear Channel Assessment in Slotted IEEE 802.15.4 Networks

One of the major concerns in wireless sensor networks is energy saving due to lack of power sources. IEEE 802.15.4 provides CSMA/CA to reduce the possibility of a collision by checking whether the medium is in use. This checking operation is CCA (Clear Channel Assessment). Currently, IEEE 802.15.4 defines CCA as two consecutive channel assessment for slotted CSMA/CA. Obviously, always performing the channel assessment twice is wasteful and inefficient, since it requires more delay and energy consumption than when the channel assessment is performed once. In this paper, we propose a SCCA (Short Clear Channel Assessment) scheme which performs the channel assessment once, not twice, with minimal effort. Simulation results show that the SCCA operation provides reduced CCA processing time and energy consumption than when IEEE 802.15.4 CCA is used.