Opportunistic interference cancellation for MIMO systems

A novel protocol design across the physical and MAC layers of a multiple antenna station (MIMO station) called MIMO-IC (multiple-input-multiple-output interference cancellation) is proposed to address the co-channel interference problem between the single antenna stations (SISO stations) and the MIMO stations. MIMO-IC enables MIMO stations to cancel interference to and from the neighboring SISO stations opportunistically so that two MIMO stations may establish a link between them along with an existing SISO link within the same contention floor without causing interference between the two links. The simulation results show that both the link throughput and the latency between two MIMO stations are improved significantly as the number of active SISO stations increases within the contention floor while the throughput of the SISO links remains unaffected. A null-forming prototype is developed using commercially available 802.11n silicon to show that the interference can be attenuated by 15 dB for a static channel and by 12 dB for a dynamic channel at 10 km/hr.