A new analytical model for the IEEE 802.15.4 CSMA-CA protocol
We give new analytical results for the performance of a wireless sensor network using the energy-conserving CSMA-CA MAC protocol of IEEE 802.15.4. We derive the throughput both under saturation and under a nonsaturation scenario in a star network involving periodic traffic, and validate the accuracy of our results using simulation for both acknowledgement and non-acknowledgement modes. Our analysis relies on the solution of a fixed point equation, and we prove the existence and uniqueness of the fixed point for the saturated case. The initial backoff window that maximizes saturation throughput is derived, and shown to be an approximately linear function of the number of active nodes. We also study the saturation model when the number of nodes tends to infinity, and obtain a simple expression for the asymptotic throughput.