Out-of-system (OoS) interference is a potential limitation for distributed networks that operate in unlicensed spectrum or in a spectrum sharing scenario. The OoS interference differs from the in-system interference in that OoS signals and their associated channels (or even their statistics) are completely unknown. In this paper, we propose a novel distributed algorithm that can mitigate OoS interference in the uplink and suppress the signal transmission in the OoS direction in the downlink. To estimate the OoS interference, each access point (AP), upon receiving an estimate of OoS interference from a previous AP, computes a better estimate of OoS interference by rotate-and-average using Procrustes method and forwards the estimates to the next AP. This process continues until the central processing unit (CPU) receives the final estimate. Our method has comparable performance to that of a fully centralized interference rejection combining algorithm and has much lower fronthaul load requirements.

翻译：系统外（OoS）干扰是分布式网络在非授权频谱或频谱共享场景下运行的一个潜在限制。与系统内干扰不同，OoS信号及其相关信道（甚至其统计特性）完全未知。本文提出一种新颖的分布式算法，可在上行链路中缓解OoS干扰，并在下行链路中抑制OoS方向上的信号传输。为估计OoS干扰，每个接入点（AP）在收到前一个AP的OoS干扰估计后，通过Procrustes方法进行旋转取平均计算更优的OoS干扰估计，并将估计值转发至下一个AP。此过程持续进行直至中央处理单元（CPU）接收到最终估计值。我们的方法性能可与完全集中式干扰抑制合并算法相媲美，且前传负载要求显著降低。