Network Scalability Comparison of IEEE 802.15.4 and Receiver-Assigned CDMA

Many future wireless sensor networks will feature very high node density and low data rates per node as well as the desire for low latency and high network dependability. Existing medium access control (MAC) layer protocols, namely IEEE 802.15.4, may not be suitable for these networks due to their reliance on carrier sense multiple access with collision avoidance (CSMA-CA) contention processing. A modified IEEE 802.15.4 MAC protocol that supports a receiver-assigned code division multiple access (RA-CDMA) contention mechanism is modeled in this paper, and is shown to enable higher network scalability while improving network performance and contributing additional robustness against interferers. This paper focuses on a comparison of the contention mechanisms and the network scalability of IEEE 802.15.4 nonbeacon enabled mode and RA-CDMA, along with a MATLAB simulation framework used for end-to-end simulations of the protocols. Simulations suggest that IEEE 802.15.4 networks begin to break down in terms of throughput, latency, and delivery ratio at a relatively small overall network size compared to RA-CDMA networks. Results show that networks using the proposed RA-CDMA multiple access can support node densities approximately two to three times higher than IEEE 802.15.4 with minimal changes to the IEEE 802.15.4 MAC, in addition to lower latencies and improved interference mitigation.