基于导频时分复用的多中继协同通信系统频域信道估计算法

A pilot time division multiplexing based channel estimation algorithm for multi-relay cooperative communication systems

针对频率选择性衰落环境下结合正交频分复用技术的放大转发多中继协同通信系统，提出了基于导频时分复用的频域信道估计算法，包括最小二乘（LS）估计算法和低阶近似的线性最小均方误差（Lr-LMMSE）估计算法。理论分析和仿真结果表明，该算法不仅能成功分辨多中继协同通信系统的所有频域信道衰落系数，避免各中继节点转发的导频符号在目的节点上的混叠干扰，而且减少频域信道估计所需的导频符号数量和时隙周期长度，提高协同通信系统的传输效率和频谱利用率，同时显著提高信道估计的精度，降低算法的复杂度，具有较高的实用价值。

A training sequence aided frequency-domain channel estimation algorithm based on pilot time division multiplexing was proposed for orthogonal frequency division multiplexing （OFDM） based amplify-and-forward （AF） cooperative communication systems with multiple relay nodes over frequency-selective fading channels, including the least squares （LS） estimation method and the low-rank linear minimum mean square error （Lr-LMMSE） estimation method. The theoretical analysis shows that the proposed algorithm can achieve the entire frequency-domain channel fading coefficients of multi- node AF cooperative communication systems successfully and avoid the superposition of the pilot symbols transmitted by different relay nodes. Moreover, the proposed algorithm can decrease the pilot symbols and time slots for channel estimation than the traditional algorithms, thus the transmission capacity and spectrum efficiency of the AF cooperative communication system can be improved. And the lower complexity and the higher practicality and accuracy of the proposed algo- rithm were confirmed by the simulation results.