Realizing High Performance Multi-Radio 802.11n Wireless Networks
The authors explore the design of a high capacity multi-radio wireless network using commercial 802.11n hardware. They first use extensive real-life experiments to evaluate the performance of closely located 802.11n radios. They discover that even when tuned to orthogonal channels, co-located 802.11n radios interfere with each other and achieve significantly less throughput than expected. The analysis reveals that the throughput degradation is caused by three link-layer effects: triggering of carrier sensing, out of band collisions and unintended frequency adaptation. Using physical layer statistics, they observe that these effects are caused by fundamental limitations of co-located radios in achieving signal isolation.