OFDM压缩感知信道估计中导频图案设计

为提高基于压缩感知的正交频分复用（orthogonal frequency-division multiplexing，OFDM）系统信道估计性能，研究了导频图案设计问题.在分析传统导频设计准则所存在问题的基础上，将测量矩阵和单位阵之间的欧式距离作为测量矩阵相关性的定义，进而得到新的基于互相关性最小化的导频设计准则；同时提出一种基于并行树的循环替换导频搜索算法，在每次循环时，依次替换各分枝节点中的每个导频位置，按照导频设计准则，采用先分枝内后分枝间选优的方法，避免了局部最优但全局错误的问题.仿真结果表明，使用新准则来设计导频可以提升稀疏信道估计效果，同时新的导频搜索算法具有较好的收敛性. 

The Pilot Pattern Design for OFDM Compressed Sensing Channel Estimation

In order to improve the channel estimation performance of OFDM (orthogonal frequency-division multiplexing) based on compressed sensing, the problem of pilot pattern design was discussed. Analyzing the problem of traditional pilot design criterion, the Euclidean distance between the measurement matrix and the identity matrix was used as the definition of correlation of measurement matrix. Then a new pilot design criterion was gotten based on correlation minimization. At the same time, a cyclic substitution search algorithm based on the parallel trees was also proposed. At each cycle, only one pilot position of each branch was substituted. According to the pilot design criterion, the better ones were chosen in every branch first and among all the branches latter to avoid the locally-optimal but globally-incorrect selections. Simulation results demonstrate that the new pilot design criterion can obtain substantial improvement in sparse channel estimation, while the new search algorithm has better convergence.