Carrier Sense Multiple Access Communications on Multipacket Reception Channels: Theory and Applications to IEEE 802.11 Wireless Networks

Multipacket reception (MPR) refers to physical layers where receivers can decode multiple simultaneously transmitted packets. In this paper we investigate the resulting performance of conjoining carrier sense multiple access (CSMA) communications with MPR. We report on its maximum achievable stable throughput with decentralized control and show there can be throughput gain over slotted ALOHA (S-ALOHA), the non-channel-sensing protocol of choice. However, this gain diminishes as the physical layer's MPR strength increases, thereby diminishing the need for channel sensing. Nonetheless, for systems evolving from a single-user (SU) to a multiple-user (MU) channel, CSMA can furnish significantly more efficient utilization of MPR capacity than S-ALOHA. This is meaningful in practice because the emerging generation of the widely deployed IEEE 802.11 wireless local area networks (WLAN) - 802.11ac - is adapting MPR and will operate in said region. In that regard, we also discuss the effective usage of a channel's resources for MPR and highlight the advantages multiuser-MIMO (MU-MIMO), an MPR technique, can offer to WLANs. Using early design specifications of 802.11ac, we show that the existing SU-oriented 802.11 MAC parameters can under-utilize the MPR capacity offered by a MU-oriented physical layer.