Reinvestigating Channel Orthogonality - Adjacent Channel Interference in IEEE 802.11n Networks
In this paper, the authors analyze the adverse effects of Adjacent Channel Interference (ACI) on 802.11 with a focus on new 802.11n standard. ACI is causing problems that are related to the carrier sensing mechanism in 802.11. On the one hand, the carrier sensing is sometimes too restrictive thus preventing concurrent transmissions which leads to a variant of the exposed terminal problem. On the other hand, the carrier sensing is sometimes too optimistic thus causing packet collisions which is a form of the hidden node problem. Both problems are especially severe in multi-radio systems, where the radios are very closely spaced. Such problems already investigated in 802.11a/b/g still remain with 802.11n.