Broadcast-Multicast Single Frequency Network versus Unicast in Cellular Systems

Video is an important factor of the load in cellular networks due to the growing popularity of streaming and linear services. In unicast transmission mode, the same data is transmitted as many times as the number of receivers demanding the same video content. Conversely, in broadcast transmissions using the Single Frequency Network (SFN) technique, a set of base stations perform synchronized transmission of the same waveform to a potentially infinite number of users. The objective of this study is to compare the performance of unicast and broadcast. More precisely, we determine the minimum number of users downloading the same data from which a broadcast transmission is more efficient than multiple unicast transmissions. In this paper, a model to calculate the Signal-to-Interference-plus-Noise Ratio (SINR) in unicast and broadcast modes is presented, considering Poisson distributed base stations, path loss, fading, shadowing, trisectored antennas, SFN with a different number of base stations and beamforming in unicast mode. Results show that even when an SFN is formed by just 2 base stations and unicast transmissions are performed using beamforming with 8 antennas per sector, broadcast outperforms unicast when there are at least 8 users per cell demanding the same content.