Low-Latency Millimeter-Wave Communications: Traffic Dispersion or Network Densification?

TL;DR

This paper compares traffic dispersion and network densification strategies for reducing delay in mmWave communications, analyzing their effectiveness through probabilistic delay bounds and effective capacity, and proposes a hybrid approach for optimal performance.

Contribution

It introduces a comprehensive analysis of delay reduction strategies in mmWave networks using stochastic network calculus, including a hybrid scheme, with validated bounds and insights for optimal scheme selection.

Findings

Traffic dispersion outperforms densification at high system gain and arrival rates.

Increasing relay density and independent paths always benefits delay performance.

Optimal transmission scheme depends on traffic load and system service conditions.

Abstract

This paper investigates two strategies to reduce the communication delay in future wireless networks: traffic dispersion and network densification. A hybrid scheme that combines these two strategies is also considered. The probabilistic delay and effective capacity are used to evaluate performance. For probabilistic delay, the violation probability of delay, i.e., the probability that the delay exceeds a given tolerance level, is characterized in terms of upper bounds, which are derived by applying stochastic network calculus theory. In addition, to characterize the maximum affordable arrival traffic for mmWave systems, the effective capacity, i.e., the service capability with a given quality-of-service (QoS) requirement, is studied. The derived bounds on the probabilistic delay and effective capacity are validated through simulations. These numerical results show that, for a given average system gain, traffic dispersion, network densification, and the hybrid scheme exhibit different potentials to reduce the end-to-end communication delay. For instance, traffic dispersion outperforms network densification, given high average system gain and arrival rate, while it could be the worst option, otherwise. Furthermore, it is revealed that, increasing the number of independent paths and/or relay density is always beneficial, while the performance gain is related to the arrival rate and average system gain, jointly. Therefore, a proper transmission scheme should be selected to optimize the delay performance, according to the given conditions on arrival traffic and system service capability.