Performance Analysis of IEEE 802.15.4 Unslotted CSMA/CA Networks, Under Fading Channels and Saturated Tra?c Conditions.

Abstract

Appeared in 2003, IEEE 802.15.4 is the standard used in low-power; low-power wireless personal area networks (WPANs). This standard defines the physical (PHY) layer and the Medium Access Control (MAC) sub-layer of the OSI model.IEEE 802.15.4 de?nes the medium access control and physical layer for sensor networks. One of the MAC schemes proposed is unslotted Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA). The MAC sublayer defines two modes for channel access: beacons mode and non-beacon mode. In beacon mode the CSMA/CA slotted mechanism is used and in the non-beacon mode the CSMA/CA unslotted mechanism is used. In this work we proposed an analytical model with Markov chains to evaluate the performance of CSMA/CA unslloted mechanism. In the modeling we considered the transmission errors and we assumed that each station always has a packet in to transmit it.  Based on this analysis model, we compute the reliability, energy consumption and normalized throughput.