Spectrum handoff decision algorithm with dynamic weights in cognitive radio networks

While primary users (PU) arrive in cognitive radio networks, the current spectrum handoff scheme is that secondary users (SU) have to vacate the spectrum bands which is used and move to other available spectrum bands. This brings frequent spectrum handoffs and degrades the performance of SU even results in service interrupt. Actually SU can still continue to transmit (Underlay) as long as the interference at PU does not exceed a certain threshold. However, the coverage of Underlay is restricted. To overcome aforementioned problem, it is proposed a multi-cell spectrum handoff scheme as a supplement on the coverage of Underlay. Simple additive weights decision algorithm with dynamic weights (SAW-DW) in spectrum handoff is used to select optimal target cell for SU to avoid service interrupt when SU exceeds Underlay constraint. Theoretical analysis and simulation results show that the scheme and algorithm can reduce the probability of handoff failure and service interrupt of SU and improve quality of service.