A hybrid handoff strategy based on dynamic spectrum aggregation in cognitive radio system

Spectrum aggregation (SA) is known as a technology permitting a primary user (PU) or a secondary user (SU) to occupy several idle bands simultaneously for transmitting numerous data. In LTE-A scenario, users can apply SA technology for media broadcasting or network video by utilizing scatted spectrum fragments. However, it´s still a problem that how the number of handoff and the delay of a secondary user can be reduced so as to accomplish the similar performance dynamically once the primary user dominates in cognitive radio system. This paper proposes a handoff strategy based on dynamic spectrum aggregation (DSA) in cognitive radio (CR) system to illustrate the spectrum handoff behavior of a secondary user. Also a backup- channel-selection strategy is advised to solve the problem of high delay brought about by the number of handoff. Finally, simulation results present that the handoff strategy based on DSA with the backup channel selection can reduce the number of handoff and shorten the delay of handoff.