For efficient implementation of 5G base stations, cloud-radio access network (C-RAN), where distributed units (DUs) are connected to a central unit (CU) through a fronthaul, has been considered. To support 5G with a wide bandwidth and large number of antennas, the fronthaul capacity becomes one of the limitations. To mitigate this problem, moving more blocks from the CU to the DU has been considered. One of the split options for the uplink is to deliver data and pilot symbols separately from a DU to a CU. For more efficiency in the fronthaul, the compression of data and pilot symbols has been adopted. As an objective of optimization, both the maximization of the uplink user rate and minimization of the fronthaul rate are considered. The optimization of the transmit powers and distortion variances of data and pilot symbols is considered. The closed-form expressions of the optimal variances of the data and pilot signal distortions with fixed data and pilot power are derived. Additionally, the optimal power allocation between the data and pilot signals are obtained when the data and pilot distortion variances caused by compression are fixed. Using an alternating optimization, the convergent solutions to the joint optimization problem can be obtained.

中文翻译：

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上行C-RAN中数据和导频信号功率和前传压缩的联合优化

为了有效实施5G基站，已经考虑了云无线电接入网络（C-RAN），其中分布式单元（DU）通过前传连接到中央单元（CU）。为了支持具有宽带宽和大量天线的5G，前传容量成为限制之一。为了减轻这个问题，已经考虑了将更多的块从CU移动到DU。上行链路的拆分选项之一是将数据和导频符号从DU分别传送到CU。为了提高前传效率，已采用数据和导频符号的压缩。作为优化的目的，要同时考虑上行链路用户速率的最大化和前传速率的最小化。考虑了数据和导频符号的发射功率和失真方差的优化。推导了数据的最佳方差以及具有固定数据和导频功率的导频信号失真的闭式表达式。另外，当由压缩引起的数据和导频失真方差固定时，可获得数据和导频信号之间的最佳功率分配。使用交替优化，可以获得联合优化问题的收敛解。