Spectrum hand-off schemes and optimum utilization of spectrum holes in cognitive radio networks

Two main problems in wireless communications are (1) limited available spectrum and (2) inefficiency in the spectrum allocation policy. These problems lead to the blocking of both initial and hand-off calls. We propose a spectrum allocation scheme in two phases. In the first phase, a collision between two calls for spectral band allocation is resolved. In second phase, spectral band allocation among a number of calls is considered. The main objective for the schemes is to minimize the forced termination of hand-off calls and an opportunistic spectrum channel allocation is achieved by assigning different priority levels to different calls.