Ergodic Rate of Millimeter Wave Ad Hoc Networks

Abstract

In this paper, we use a stochastic geometry approach to quantify the ergodic rate of each user in an outdoor mm-wave ad hoc network. For a variety of use cases, it is reasonable to assume users will be clustered around a central point (e.g., WiFi hotspot or clusterhead) rather than uniformly distributed. Our results indicate that, in contrast to sub-6-GHz networks, clustered mm-wave ad hoc networks tolerate the increased interference because directional antenna arrays reduce the interference. For certain antenna array configurations and user densities, uncoordinated users within a cluster outperform TDMA. Additionally, we derive a scaling law for uniform mm-wave ad hoc networks and propose a heuristic scaling for clustered networks. The per user ergodic rate remains constant if mm-wave antenna arrays scale sub-linearly with the number of users for uniform networks or linearly in clustered networks as users are added to the cluster. Last, we compute expressions that quantify the loss in ergodic rate per user when alignment error occurs at the receiver and transmitter. Our results show that even relatively small errors in alignment can lead to significant ergodic rate reduction.