Multi-Antenna Transmission in Downlink Heterogeneous Cellular Networks under A Threshold-based Mobile Association Policy

TL;DR

This paper analyzes multi-antenna downlink heterogeneous cellular networks using a threshold-based mobile association policy, deriving outage probabilities and demonstrating improvements in spectrum and energy efficiency through threshold tuning.

Contribution

It introduces a novel reliability-oriented mobile association policy and provides analytical expressions for outage probability in multi-tier HCNs, including bounds and asymptotic behavior.

Findings

Large access thresholds reduce outage probability.

Proper threshold selection improves spectrum efficiency.

Proper threshold selection enhances energy efficiency.

Abstract

With the recent emergence of 5G era, heterogeneous cellular networks (HCNs) have invoked a popular research interest. In this paper, we provide a comprehensive analysis for multiantenna transmissions in a multi-tier downlink HCN. We first propose a reliability-oriented threshold-based mobile association policy, where each user connects to the strongest base station from which this user can obtain the largest truncated long-term received power. Under our mobile association policy, we derive analytical expressions for the exact outage probability of an arbitrary randomly located user, along with computationally convenient lower and upper bounds. Asymptotic analysis on the outage probability shows that introducing a large access threshold into mobile association significantly decreases the outage probability. We further investigate the spectrum efficiency and the energy efficiency of the HCN. Our theoretic analysis and numerical validations show that both the spectrum and energy efficiencies can be improved by properly choosing the access threshold.