The Potential Gains of Macro-Diversity in Outdoor and Indoor mmWave Cellular Networks

Envision a future where entire 4K movies can be transferred in under a second, autonomous vehicles seamlessly interact with city traffic systems in real-time, and global phone calls remain uninterrupted regardless of location. The sixth generation of cellular technology (6G) has the potential to realize this vision. However, a significant challenge arises in the use of millimeter-wave (mmWave) frequencies, which are fundamental to 6G's high-speed capabilities. These frequencies have limited propagation distances and are highly susceptible to blockages caused by common environmental obstacles such as buildings, trees, and even pedestrians. This paper examines the impact of mmWave signal obstructions on the Ohio Northern University (ONU) campus. By incorporating field measurements into an analytically validated simulation model, the paper evaluates the effects of physical obstacles, such as buildings and walls, on mmWave signal performance and overall network reliability. In addition to analyzing the outdoor campus environment, the study investigates the James Lehr Kennedy Engineering Building to assess the distinct challenges and strategies required for ensuring robust 6G connectivity in both indoor and outdoor settings. The probability of a device maintaining a line-of-sight (LOS) connection to one or more base stations and successfully accessing the network is quantified for each scenario. The results highlight macrodiversity as an effective solution to mitigate the challenges associated with mmWave frequency deployment. By enabling simultaneous connections to multiple base stations within a given area, macrodiversity significantly enhances the probability of LOS while optimizing the number of base stations required for adequate coverage. A comparative analysis of indoor and outdoor environments indicates that outdoor deployment offers greater reliability at a lower cost. The earlier saturation point and reduced sensitivity to obstructions enable a high probability of LOS (PLOS) with fewer base stations, particularly as 6G infrastructure trends toward extended coverage radii. Unlike the accelerated rollout of 5G, which resulted in coverage inconsistencies and public misconceptions, this paper addresses the challenges of 6G implementation at an early stage. By drawing on lessons learned from previous generations, this study aims to support the development of a more reliable, efficient, and widely accepted 6G network.