Combining successive interference cancellation and CSMA/CA in a beam forming IEEE 802.15.4 gateway

We propose a novel method to maximise the aggregate throughput of an enhanced IEEE 802.15.4 gateway. By exploiting the gateway´s beamforming antenna array and successive interference cancellation (SIC) we simultaneously increase range and maximise throughput. Our algorithm organises nodes into clusters, with each cluster assigned a unique spreading code and target gateway receive power. Within a cluster, nodes share the medium via CSMA/CA and inter-cluster packet collisions at the gateway are resolved with SIC. Theoretical throughput gains are calculated and then verified with cross layer simulations encompassing ray trace based propagation modelling, IEEE 802.15.4 bit error rate (BER) models, and a discrete event based enhanced MAC simulator. A 4.3x improvement in aggregated throughput is shown in simulations, reflecting the theoretical analysis and providing a systematic approach for throughput optimization.