Implementation of Channel Hopping Algorithm in Cognitive Radio Network & MANET

Dynamic spectrum access by the unlicensed secondary users (nodes) in the Cognitive Radio Network without harmful (potential) interference to the licensed users is an intelligent and efficient use of the Licensed Spectrum Bands. The nodes in a cognitive radio network(CRN) performs periodic local spectrum sensing & dynamically detects the vacant or unused spectrum around them in the form of free channels or spectrum holes which are used for communication among cognitive radio(CR) nodes. If any vacant channel is detected by the secondary user or CR node, it is strictly the responsibility of the CR node to vacate the channel upon the return of Primary User (PU) so that the Licensed user doesn‟t get any potential interference from the CR user. This paper presents an algorithm called „Vacate on Demand algorithm‟ which performs two main functions.1) Vacating the channel by CR user in case of PU return or after the completion of every sensing interval.2) Moving the CR user to some other vacant channel. After the completion of periodic spectrum sensing activity by CR nodes, based on the sensing results, a ranking table is formed which contains the total channels arranged from bottom to top in the order of Primary User activity. The algorithm uses this ranking table for quickly vacating the occupied channel by CR user in case of PU return & dynamically searches for vacant channel in the ranking table. This paper also compares the expected time to get a free channel in CRN with that of a MANET (Mobile Ad hoc Network).The performance of the above algorithm is analyzed using MATLAB simulation.