To Buffer or to Switch: Design of Multichannel MAC for OSA Ad Hoc Networks

We present an analytical framework to assess the effectiveness of different combinations of medium access control (MAC) protocols for multichannel opportunistic spectrum access (OSA) ad hoc networks. As a performance metric we focus on average link layer throughput, and investigate dedicated control channel (DCC) and hopping control channel (HCC) MAC protocol abstractions. For DCC and HCC protocol classes we analyze two distinct strategies of managing active secondary user (SU) connection on the event of primary user (PU) arrival: to buffer the connection until PU leaves, or to switch the existing SU connection to a vacant channel. We come to an interesting conclusion: while, intuitively, OSA MAC protocols that support both SU connection buffering and SU connection switching should obtain the highest throughput, due to the channel switching overhead SU connection buffering alone performs better than the rest of the protocol combinations considered.