A sequential fronthaul network, referred to as radio stripes, is a promising fronthaul topology of cell-free MIMO systems. In this setup, a single cable suffices to connect access points (APs) to a central processor (CP). Thus, radio stripes are more effective than conventional star fronthaul topology which requires dedicated cables for each of APs. Most of works on radio stripes focused on the uplink communication or downlink energy transfer. This work tackles the design of the downlink data transmission for the first time. The CP sends compressed information of linearly precoded signals to the APs on fronthaul. Due to the serial transfer on radio stripes, each AP has an access to all the compressed blocks which pass through it. Thus, an advanced compression technique, called Wyner-Ziv (WZ) compression, can be applied in which each AP decompresses all the received blocks to exploit them for the reconstruction of its desired precoded signal as side information. The problem of maximizing the sum-rate is tackled under the standard point-to-point (P2P) and WZ compression strategies. Numerical results validate the performance gains of the proposed scheme.

翻译：一种称为射频条带的序贯前传网络，是无蜂窝MIMO系统中极具前景的前传拓扑结构。在该架构下，单根电缆即可连接接入点与中央处理器，因此相较于需为每个接入点配备专用电缆的传统星型前传拓扑更具优势。现有关于射频条带的研究主要集中于上行通信或下行能量传输，本文首次针对下行数据传输设计问题展开研究。中央处理器将线性预编码信号的压缩信息通过前传链路发送至接入点。由于射频条带采用串行传输机制，每个接入点均可访问其路径上的所有压缩块。据此可应用名为温纳-齐夫（WZ）压缩的先进压缩技术：每个接入点解压所有接收到的数据块，并将其作为边信息用于重建自身所需的预编码信号。本文在标准点对点压缩与WZ压缩策略框架下，以最大化系统和速率为目标展开研究。数值结果验证了所提方案的性能增益。