Optimal primary pilot power allocation and secondary channel sensing in cognitive radios
Heejung Yu · IET Communications · 2016
Channel sensing in cognitive radio systems is examined with the objective to optimise primary user's power allocation in pilot signals in order to maximise the sum rate of both primary and secondary links. The pilot signal of the primary transmitter can be used not only for channel estimation at the primary receiver, but also for channel sensing at the secondary transmitter. A tradeoff exists between channel‐sensing performance and the sum rate of primary and secondary links. At first, the sum rate of primary and secondary networks can be increased by selecting the optimal operating point of channel sensing when a pre‐determined pilot is given. When pilot power can be controlled, the problem is formulated as a joint optimisation problem for the channel‐sensing performance and power allocation at the pilot signal. Using the optimal solutions, the maximum sum rate can be achieved. This joint optimisation problem has a unique solution that can be found numerically with an iterative manner and it has fast convergence characteristic. Channel sensing of the secondary user as well as an achievable rate of the primary user is considered in primary pilot power allocation.