In this paper we consider a wireless receiver model that employs the macro diversity (MD) technique, consisting of a selection combining (SC) receiver fed by two micro diversity (mD) SC branches, which is used to simultaneously reduce the effects of Nakagami-m short term fading, Gamma long term fading, and co-channel interference on the system performances. The interfering signal is also affected by the same propagation environment as is the case for the desired signal. We derive, closed form expressions for level crossing rate (LCR) of signal-to-interference ratio at the outputs of the mD SC with n branches, as well as for the signal-to-interference ratio at the output of the whole MD SC receiver. By using the obtained expression for LCR of signal-to-interference ratio at the output of the MD SC receiver, we can further determine average fade duration of proposed system configuration. We investigate and analyze the influence of Nakagami parameter m, the average value of desired signal envelope, and the average value of co-channel interference envelope on the LCR. This work is of great importance in the design of envisioned 5G wireless communication systems in the presence of the combined effects of fading and interference. Also, the LCR is important to system performance because, for example, the LCR influences the error correction code's performance.

在本文中，我们考虑一种采用宏分集（MD）技术的无线接收器模型，该模型由两个微分集（mD）SC分支馈送的选择组合（SC）接收器组成，用于同时减少Nakagami-米短期衰落，伽玛长期衰落和同信道干扰的系统的性能。干扰信号还受到与所需信号相同的传播环境的影响。我们得出mD SC输出为n时信噪比的电平穿越率（LCR）的闭式表达式分支，以及整个MD SC接收器输出的信噪比。通过在MD SC接收器的输出端使用获得的LCR信号干扰比的表达式，我们可以进一步确定所提出系统配置的平均衰落持续时间。我们调查并分析了中上参数m，所需信号包络的平均值以及同频道干扰包络的平均值对LCR的影响。在存在衰落和干扰的综合影响的情况下，这项工作对设想的5G无线通信系统的设计至关重要。而且，LCR对系统性能也很重要，因为例如，LCR影响纠错码的性能。