Millimeter Wave Ad Hoc Networks: Noise-limited or Interference-limited?

TL;DR

This paper analyzes whether millimeter wave ad hoc networks are noise-limited or interference-limited, providing closed-form expressions for throughput and proposing an adaptive hybrid resource allocation framework to optimize performance.

Contribution

It introduces a new analytical framework revealing the transitional behavior between noise-limited and interference-limited regimes in mmWave networks and proposes an adaptive resource allocation strategy.

Findings

mmWave networks can transition from noise-limited to interference-limited regimes

Derived closed-form expressions for collision probability and throughput

Proposed a hybrid resource allocation framework for adaptive management

Abstract

In millimeter wave (mmWave) communication systems, narrow beam operations overcome severe channel attenuations, reduce multiuser interference, and thus introduce the new concept of noise-limited mmWave wireless networks. The regime of the network, whether noise-limited or interference-limited, heavily reflects on the medium access control (MAC) layer throughput and on proper resource allocation and interference management strategies. Yet, alternating presence of these regimes and, more importantly, their dependence on the mmWave design parameters are ignored in the current approaches to mmWave MAC layer design, with the potential disastrous consequences on the throughput/delay performance. In this paper, tractable closed-form expressions for collision probability and MAC layer throughput of mmWave networks, operating under slotted ALOHA and TDMA, are derived. The new analysis reveals that mmWave networks may exhibit a non-negligible transitional behavior from a noise-limited regime to an interference-limited regime, depending on the density of the transmitters, density and size of obstacles, transmission probability, beamwidth, and transmit power. It is concluded that a new framework of adaptive hybrid resource allocation procedure, containing a proactive contention-based phase followed by a reactive contention-free one with dynamic phase durations, is necessary to cope with such transitional behavior.