Frequency hopping in Cognitive Radio Networks: A survey

Nowadays, with this diversity of Communication devices, the demand for accessing the spectrum is extremely increased. Cognitive Radio Network(CRN) improves the utilizing of the available spectrum efficiently and without it a considerable portion of the assigned spectrum is used intermittently. The geographical variations of using the assigned spectrum ranges remarkably with a high variance in time and place. Among Lots of the medium access control (MAC) protocols proposed, channel-hopping-based medium access control protocols enhance the capacity in decentralized multichannel CRN´s without utilizing extra control channels.In order to transmit, each secondary user (SU) should stochastically follow a channel hopping sequence to establish a free channel. This paper addresses a survey on the basis of the channel hopping and reviews the channel hopping MAC in aspects of spectrum sharing ,related protocols, rendezvouses and control channel selection and so on.