论文标题
通过QCQP的强双重性，在量化的通道反馈下进行了强大的下行链路传输优化
Robust Downlink Transmit Optimization under Quantized Channel Feedback via the Strong Duality for QCQP
论文作者
论文摘要
考虑在频划分双面系统中强大的多输入单输出下行链接优化问题。基站（BS）将培训信号发送给用户，每个用户估计频道系数，量化估计通道的增益和方向，并将其发送回BS。假设发射机处的通道状态信息主要是由于通道方向量化误差，通道估计误差和过时的通道效应，这是不完美的。实际信道被建模为不确定性集，由两个不平等均等和一个平等不均匀的二次约束组成，以说明上述错误和效果。然后，将发射功率最小化问题制定为符合强大的信号到噪声加率限制的约束。相对于波束成形向量，每个鲁棒约束都等效地转换为二次矩阵不等式（QMI）约束。转换是通过等效相位旋转过程和二次约束二次程序的强双重性结果来实现的。因此，最小化问题将其变成了QMI问题，并且通过有限的线性矩阵不等式松弛和其他有效的凸约限制来解决该问题。给出了仿真结果，以证明所提出的方法的性能，并显示限制放松的效率。
Consider a robust multiple-input single-output downlink beamforming optimization problem in a frequency division duplexing system. The base station (BS) sends training signals to the users, and every user estimates the channel coefficients, quantizes the gain and the direction of the estimated channel and sends them back to the BS. Suppose that the channel state information at the transmitter is imperfectly known mainly due to the channel direction quantization errors, channel estimation errors and outdated channel effects. The actual channel is modeled as in an uncertainty set composed of two inequality homogeneous and one equality inhomogeneous quadratic constraints, in order to account for the aforementioned errors and effects. Then the transmit power minimization problem is formulated subject to robust signal-to-noise-plus-interference ratio constraints. Each robust constraint is transformed equivalently into a quadratic matrix inequality (QMI) constraint with respect to the beamforming vectors. The transformation is accomplished by an equivalent phase rotation process and the strong duality result for a quadratically constrained quadratic program. The minimization problem is accordingly turned into a QMI problem, and the problem is solved by a restricted linear matrix inequality relaxation with additional valid convex constraints. Simulation results are presented to demonstrate the performance of the proposed method, and show the efficiency of the restricted relaxation.
