This letter considers downlink wideband channel estimation in an asymmetrical full-digital system where the number of uplink receive radio frequency chains is less than that of the downlink. This channel inconsistency will reduce downlink channel estimation accuracy. To deal with this problem, we adopt the coprime array topology in uplink receive antennas. Then, two iterative algorithms which are based on alternating direction method of multipliers and block-sparsity orthogonal matching pursuit, respectively, are developed to rebuild downlink channel. Simulation results demonstrate the effectiveness of the proposed scheme in the asymmetrical full-digital system.

中文翻译：

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非对称全数字系统的下行宽带信道估计

这封信考虑了非对称全数字系统中的下行链路宽带信道估计，其中上行链路接收射频链的数量少于下行链路的数量。这种信道不一致会降低下行信道估计的准确性。为了解决这个问题，我们在上行接收天线中采用互质阵列拓扑。然后，分别开发了基于乘法器交替方向法和块稀疏正交匹配追踪的两种迭代算法来重建下行信道。仿真结果证明了该方案在非对称全数字系统中的有效性。