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In cognitive radio network (CRN) where primary user (PU) and secondary user (SU) wish to communicate with their corresponding receivers simultaneously over frequency selective fading channels,the interference between PU and SU should be eliminated in order to realize spectrum sharing.Precoder division multiple access (PDMA) that implements Vandermonde precoder in cognitive orthogonal frequency division multiplexing (OFDM) is proposed,which benefits from the frequency selectivity of the cognitive channel to form a frequency beam-former.Vandermonde precoder enables SUs to achieve higher bit rate with optimal power allocation strategy under the condition of PU interference constraint.Numerical and simulation results are presented to prove theoretical derivations.It is shown that,achievable bit rates (ABR) of SU could be achieved with optimal power allocation scheme in CRN.Meanwhile,it is also verified that,with Vandermonde precoder to form PDMA,SU’s signal-to-noise ratio (SNR) and the target rate of PU could impact the ABR of SU significantly in CRN.
In cognitive radio network (CRN) where primary and secondary users (SU) wish to communicate with their corresponding receivers simultaneously over frequency selective fading channels, the interference between PU and SU should be eliminated in order to realize spectrum sharing. division multiple access (PDMA) that implements Vandermonde precoder in cognitive orthogonal frequency division multiplexing (OFDM) is proposed, which benefits from the frequency selectivity of the cognitive channel to form a frequency beam-former. Vandermonde precoder enables SUs to achieve higher bit rate with Optimal power allocation strategy under the condition of PU interference constraint. Numerical and numerical results are presented to prove theoretical derivations. It is shown that achievable bit rates (ABR) of SU could be achieved with the optimal power allocation scheme in CRN.Meanwhile, it is also verified that, with Vandermonde precoder to form PDMA, SU’s signal-to-noise ratio (SNR) and the t arget rate of could could impact the ABR of SU significantly in CRN.