Multi Access-Point (M-AP) cooperation is expected to play a key role in the next-generation Wi-Fi standard (namely the upcoming IEEE WLAN 802.11bn/UHR, dubbed Wi-Fi-8), particularly in dense deployments where inter-cell interference hinders further increase in network capacity. Among the various considered AP-cooperation techniques, coherent Joint Transmission (JT) is the most ambitious, aiming at deploying an M-AP cluster as a single ‘super-AP’ serving multiple stations in a downlink Multi-User Multiple-Input Multiple-Output (DL MU-MIMO) fashion. Ideally, in the absence of practical impairments – predominantly inter-AP phase misalignment – prior-art JT schemes exhibit superior performance relative to simpler M-AP precoding schemes such as Coordinated Beam-Forming (Co-BF), equivalent to dB Signal-to-Interference-plus-Noise-Ratio gain in certain scenarios. However, the Wi-Fi standard – being based on low-cost implementation and deployment strategies as a major driver for success – cannot guarantee the required tight inter-AP synchronization levels, thus jeopardizing the JT advantage in practice (essentially wiping out the gain relative to Co-BF, in the above scenarios). As a cure, we develop a novel MIMO-precoding scheme, which preserves most of the JT gain ( out of the dB above) while being inherently resilient to phase offsets between the APs, thus paving the way to practical incorporation of JT into Wi-Fi-8.

中文翻译：

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Wi-Fi 中的 AP 协作：采用新颖的预编码方案进行联合传输，可适应发射机之间的相位偏移

多接入点 (M-AP) 合作预计将在下一代 Wi-Fi 标准（即即将推出的 IEEE WLAN 8021.1bn/UHR，称为 Wi-Fi-8）中发挥关键作用，特别是在密集部署中小区间干扰阻碍了网络容量的进一步提升。在各种考虑的 AP 协作技术中，相干联合传输 (JT) 是最雄心勃勃的，旨在将 M-AP 集群部署为单个“超级 AP”，为下行链路中的多个站提供服务。输出（DL MU-MIMO）时尚。理想情况下，在不存在实际损伤（主要是 AP 间相位失准）的情况下，现有技术的 JT 方案相对于更简单的 M-AP 预编码方案（例如协调波束形成 (Co-BF)）表现出优越的性能，相当于 dB 信号到-某些情况下的干扰加噪声比增益。然而，Wi-Fi 标准基于低成本实施和部署策略作为成功的主要驱动力，无法保证所需的严格的 AP 间同步水平，从而损害了实践中的 JT 优势（基本上消除了相对增益）到 Co-BF，在上述场景中）。作为一种解决方法，我们开发了一种新颖的 MIMO 预编码方案，该方案保留了大部分 JT 增益（超出上述 dB），同时对 AP 之间的相位偏移具有固有的弹性，从而为将 JT 实际融入 Wi-Fi 中铺平了道路。菲-8。