Power and Time Allocation Between Multiple Channels in Cognitive Radio Networks

Abstract

In this paper, we consider a wideband cognitive radio network (CRN) containing a single secondary user (SU) which can only serially sense multiple narrowband channels and thus maximize the utilization of perceived available channels. Before transmitting, during a period of time τ, SU allocates τ _i to each channel and senses whether the channel is available or not. When transmitting, SU allocates different transmit power P _i to each channel. We study the problem of designing the optimal spectrum sensing time allocation τ _i , total sensing time τ and power allocation P _i between the multiple channels so as to maximize the achievable rate of CRN subject to the constraint of the total transmit power and probability of detection. The problem is transformed into some subproblems with low complexity and solved by optimal means separately. From the time and power allocation parameters, we conclude that channels with low probability of transmission chance or low channel gain will be closed without sensing or transmission in order to get the maximum rate. We also analyze how the conclusions can be applied to the scenario of multiple SUs. Numerical investigation shows that the proposed scheme can significantly achieve spectrum access and the optimization process improves the rate obtained by CRN.