Improvements to CSMA-CA in IEEE 802.15.4

IEEE 802.15.4 is the first recognized standard that can replace the large number of proprietary PHY and MAC protocols for Low Rate Wireless Personal Area Networks (LR-WPANs). To balance the conflicting demands of low-delay data delivery and consumed energy, this standard employs CSMA-CA as the multiple-access scheme. However, a critical study of this protocol's operation under different conditions shows room for improvement. In this paper we propose two algorithms to improve the performance of this standard: time-based frame aggregation and selective frames. We evaluate these proposals under different conditions using performance indices including delay, throughput, and collision rate. Our simulation results together with analytical expressions from related work demonstrate the benefits of our proposed ideas.