Performance of Mixed Channel Cell-Free Systems

The pursuit of improving the performance of communications systems has, in recent years, led to the popularization of the concept of cell-free system. In this system, division of space in cells is abolished and base stations are replaced by low-cost access points serving all mobile terminals in the system. In the literature, the behavior of such systems has been studied considering the non line-of-sight (NLoS) condition and, more recently, LoS condition. In this work, we propose, for cell-free systems, the use of a mixed channel model, where the occurrence of both conditions is possible, depending on the distances of the links. Analyzes were performed based on the number of devices, the density of users and access points and the quality of the channel estimation. The results indicate that the densification of the system, by reducing the area, affects the three scenarios in different ways. The mixed scenario surpassed, in terms of achievable rates, the homogeneous scenario with line-of-sight.