Extended k-u Fading Model in mmWave Communication: Statistical Properties and Performance Evaluations

This study proposes a small-scale fading model, named the extended k-u model, which incorporates the imbalance of multipath clusters by adding a new parameter based on the original k-u model. The extended k-u model outperforms the k-u model in characterizing small-scale fading in the millimeter-wave (mmWave) band and has more accurate modeling capability than the extended n-u model in scenarios with line-of-sight (LoS) paths. And it is mathematically more tractable than the a-k-n-u model. Experiments are conducted for mmWave communication scenarios with LoS paths, covering the outdoor 28 GHz band, the indoor 65 GHz band, and the indoor 92 GHz band. The results demonstrate that the extended k-u model achieves a smaller mean square error in fitting the measured data compared to both the k-u model and the extended n-u model across all scenarios. In addition, through theoretical derivations, closed-form expressions are obtained for the key statistical characteristics of the extended k-u model, including the probability density function, cumulative distribution function, moments of arbitrary order, and moment generating function. Based on these statistics, this study further derives and analyzes the expressions for some performance metrics of the communication system, including the amount of fading, the probability of outage, and the average bit error rate.