Capacity and Scaling Laws of Dense mmWave and Interference Alignment Ad Hoc Networks

Ad hoc networks continue to be severely interference limited. One approach to increase capacity is to go to millimeter wave (mmWave). Higher bandwidth but also directional antennas to reduce interference. Another approach is to stay at conventional frequencies but use techniques like interference alignment (IA). In this paper, we derive the scaling laws for dense mmWave ad hoc networks with directional beamforming and ad hoc networks with IA. We also give an exact expression for the capacity of mmWave ad hoc networks with random dipole distance. Our results indicate that the number of antennas with uncoordinated beamforming must scale sub-linearly with the user density while the number of users coordinating with IA must scale super-linearly.