Optimization of valid transmission time for cognitive users
Dan Ye · Journal of PLA University of Science and Technology · 2008
In order to investigate how Secondary User shares Primary User′s free spectrum and how SU′s valid transmission time in cognitive radio is optimized, according to the flow chart,the PU′s channel state was assumed to conform to Poisson distribution,and OFDM modulation was used in SU′s physical layer.Both the influence of the number of channels SU occupied and the duration of the transmission period on the total valid transmission time were analysed and the optimal values were found respectively.MATLAB simulation was devised to verify the analysis and the result accorded with the theoretical analysis.Based on this,an important constraining condition Interference Time Ratio was studied.It′s concluded that ITR mitigates the SU′s interference to the PU,while decreases the SU′s valid transmisson time.