Implementation and experimental evaluation of multi-channel MAC protocols for 802.11 networks

Multi-channel MAC protocols have recently obtained considerable attention in wireless networking research because they promise to increase capacity of wireless networks significantly by exploiting multiple frequency bands. However, most of these protocols remain as pure academic interest since they only exist on paper and in simulation code but have no practical implementation. In this paper, we report lessons learned from our endeavor in which we implement three representative multi-channel MAC protocols: Asynchronous Multi-channel Coordination Protocol (AMCP), Multi-channel MAC (MMAC), and Slotted Seeded Channel Hopping (SSCH) on off-the-shelf IEEE 802.11 hardware. We explore practical impacts of these multi-channel MAC protocols and present results of our experimental performance evaluation. The major findings of our performance evaluation are: (1) all multi-channel MAC protocols underperform the original 802.11 MAC at low load, (2) all multi-channel MAC protocols give better performance than the original 802.11 MAC at medium and high load, (3) AMCP performs worst among all multi-channel MACs in one-hop and multi-hop 802.11b scenario but delivers the best performance in multi-hop 802.11a scenario, and (4) SSCH attains the best results in one-hop scenarios or at low loads but loses its effectiveness at high loads in multi-hop scenarios.