This paper considers a cell-free massive MIMO (CF-mMIMO) system using conjugate beamforming (CB) with fractional-exponent normalization. Assuming independent Rayleigh fading channels, a generalized closed-form expression for the achievable downlink spectral efficiency is derived, which subsumes, as special cases, the spectral efficiency expressions previously reported for plain CB and its variants, i.e. normalized CB and enhanced CB. Downlink power control is also tackled, and a reduced-complexity power allocation strategy is proposed, wherein only one coefficient for access point (AP) is optimized based on the long-term fading realizations. Numerical results unveil the performance of CF-mMIMO with CB and fractional-exponent normalization, and show that the proposed power optimization rule incurs a moderate performance loss with respect to the traditional max-min power control rule, but with lower complexity and much smaller overall power consumption.

翻译：本文考虑了无细胞大规模MIMO(CF-mMIMO)系统,该系统使用相形成形(CB),具有分数性能正常化。假设独立的Rayleg 淡化渠道,则产生可实现下链光谱效率的普遍封闭式表达方式,作为特殊情况,将先前报告的普通CB及其变体(即常规CB和强化CB)的光谱效率表达方式(即常规CB和强化CB)进行分解。还解决了下链功率控制问题,并提出了一项降低兼容性的权力分配战略,根据长期的减速实现情况,只优化了一个接入点(AP)系数。数字结果揭示了CFCMIMO的性能与CB和分数-Excon常规,并表明拟议的电优化规则在传统的最大功率控制规则方面造成适度性能损失,但复杂性较低,总功率消耗量小得多。