PERFORMANCE IMPROVEMENT OF OFDM BY PILOT-AIDED SPARCECHANNEL ESTIMATION

对于OFDM系统，基于均方信道估计误差设计导频符号的数目、位置和功率分配。所提出的方法适用于基于OFDM的认知无线电与任何空的子载波。利用非线性优化技术交叉熵优化，得到了次优的导频符号位置。导频功率分配通过求解凸优化来确定。数值仿真结果表明，该方法优于传统方法。

For OFDM systems, number, location, and power distribution of pilot symbols are designed based on mean squared channel estimation error. The proposed method is applicable to OFDM-based cognitive radio with any null subcarriers. The sub-optimal location of pilot symbols is given by using cross entropy optimization that is a non-linear optimization technique. Pilot power distribution is determined by solving a convex optimization. Numerical simulations show that the proposed method outperformsthe conventional method.