Statistical Models for RF Exposure Exclusion Zone Design in Massive MIMO Systems

Massive multiple-input multiple-output (MIMO) is a fundamental enabler to provide high data throughput in next generation cellular networks. By equipping the base stations (BSs) with tens or hundreds of antennas, narrow and high gain beams can be used to spatially multiplex several users. While increasing the achievable performance, focusing the transmit power into specific directions also poses new issues when electromagnetic field (EMF) constraints are taken into account. With massive MIMO, traditional methods imposed by regulations to design exclusion zones around BS sites tend to be very conservative, in particular when the averaging period for measuring the EMF is properly taken into account. In this work, we consider statistical models for designing the exclusion zones around massive MIMO BSs and perform extensive system simulations to evaluate how the dimension of the exclusion zone decreases with respect to the traditional approach case. The analysis is performed by considering realistic channel models, BSs fully loaded and different configurations of active users per cell. Numerical results show that statistical models are very beneficial when compared to the traditional method as they reduce to half the maximum radius of the exclusion zone.