Optimum Power Allocation for Preamble Detection With Channel-Adaptive Random Access

Channel-adaptive random access can reduce the power required for successful random access transmission in a TDD-based wireless system. With channel-adaptive random access, transmission of a random access packet is delayed until a predefined channel condition is satisfied. The performance of channel-adaptive random access has been investigated with suboptimal power allocations including constant and channel inversion power allocations. However, the optimal power allocation has not been studied for channel-adaptive random access. In this paper, the optimum power allocation is derived for channel-adaptive random access, especially considering the detection performance of a random access preamble. Some important properties are investigated for the optimum power allocation. Numerical results compare the performances of the optimum and the suboptimal power allocations.