In this paper, we propose a cross subcarrier precoder design (CSPD) for massive multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. The aim is to maximize the weighted sum-rate (WSR) performance while considering the smoothness of the frequency domain effective channel. To quantify the smoothness of the effective channel, we introduce a delay indicator function to measure the large delay components of the effective channel. An optimization problem is then formulated to balance the WSR performance and the delay indicator function. By appropriately selecting the weight factors in the objective function and the parameters in the delay indicator function, the delay spread of the effective channel can be reduced, thereby enhancing the smoothness of the effective channel. To solve the optimization problem, we apply the symplectic optimization, which achieves faster convergence compared to the gradient descent methods. Simulation results indicate that the proposed algorithm achieves satisfying WSR performance while maintaining the smoothness of the effective channel.

翻译：本文针对大规模多输入多输出正交频分复用系统，提出一种跨子载波预编码器设计方案。该方案旨在最大化加权和速率性能，同时兼顾频域等效信道的平滑性。为量化等效信道的平滑度，我们引入时延指示函数以度量等效信道中的大时延分量。通过构建兼顾加权和速率性能与时延指示函数的优化问题，并合理选择目标函数中的权重因子及时延指示函数中的参数，可有效降低等效信道的时延扩展，从而提升等效信道的平滑性。为求解该优化问题，我们采用辛优化方法，其收敛速度较梯度下降法具有显著优势。仿真结果表明，所提算法在保证等效信道平滑性的同时，能够获得令人满意的加权和速率性能。