Cognitive radio ( CR) is known as an intelligent technology allowing a secondary user ( SU) to occupy a primary user's ( PU's) band when it is idle. Appearance of the idle band may be contiguous or non-contiguous. In other words,the PU's band and the idle band are distributed alternately over the spectrum. Apparently the non-contiguous idle band cannot be fully utilized in this context. This paper proposes an algorithm to solve the problem of low utilization of the non-contiguous idle band and to increase the number of the SU who needs access to the spectrum by a static spectrum aggregation ( SSA) method combined with non-contiguous orthogonal frequency division multiplexing ( NC-OFDM) . The simulation results show that the SSA algorithm realizes at least 70% utilization of the idle band which provides access to the spectrum for as many as 30 SUs as expected.
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