Throughput and Energy Efficiency Analysis of Small Cell Networks with Multi-antenna Base Stations (1306.6169v1)

Abstract: Small cell networks have recently been proposed as an important evolution path for the next-generation cellular networks. However, with more and more irregularly deployed base stations (BSs), it is becoming increasingly difficult to quantify the achievable network throughput or energy efficiency. In this paper, we develop an analytical framework for downlink performance evaluation of small cell networks, based on a random spatial network model, where BSs and users are modeled as two independent spatial Poisson point processes. A new simple expression of the outage probability is derived, which is analytically tractable and is especially useful with multi-antenna transmissions. This new result is then applied to evaluate the network throughput and energy efficiency. It is analytically shown that deploying more BSs or more BS antennas can always increase the network throughput, but the performance gain critically depends on the BS-user density ratio and the number of BS antennas. On the other hand, increasing the BS density or the number of transmit antennas will first increase and then decrease the energy efficiency if different components of BS power consumption satisfy certain conditions, and the optimal BS density and the optimal number of BS antennas can be found. Otherwise, the energy efficiency will always decrease. Simulation results shall demonstrate that our conclusions based on the random network model are general and also hold in a regular grid-based model.

• The paper provides an analytical framework using stochastic geometry to evaluate the performance of small cell networks with multi-antenna base stations.
• It finds that network throughput always increases with base station density or antennas, but the scaling depends on the base station-user density ratio.
• Energy efficiency shows a non-monotonic behavior, suggesting that optimal base station density and antenna configurations exist to maximize efficiency.

Analysis of Throughput and Energy Efficiency in Small Cell Networks with Multi-Antenna Base Stations

The paper "Throughput and Energy Efficiency Analysis of Small Cell Networks with Multi-antenna Base Stations" by Chang Li, Jun Zhang, and Khaled B. Letaief provides a rigorous analytical framework for evaluating the performance of small cell networks, specifically focusing on network throughput and energy efficiency. This paper addresses the complex problem of assessing the downlink performance of these networks under realistic conditions characterized by the irregular deployment of base stations (BSs) and users, which are modeled as spatial Poisson point processes.

Analytical Framework

The paper formulates a comprehensive analytical approach to derive a tractable expression for the outage probability, which is crucial for performance evaluation. The framework employs stochastic geometry tools to model the locations of BSs and users, allowing for the analysis of multi-antenna transmissions under the assumption of maximal ratio transmission (MRT) beamforming at the transmitters. A significant contribution of the paper is the simplified expression for the outage probability, which facilitates the exploration of how BS density and the number of antennas impact the network performance.

Main Findings

1. Network Throughput:
   • The research finds that increasing the density of BSs or the number of antennas can always enhance network throughput. However, the extent of this improvement is significantly influenced by the BS-user density ratio.
   • In scenarios where BS density is much less than user density, the throughput scales linearly with the BS density, aligning with existing literature. However, when BS density is comparable to user density, a logarithmic scaling is observed, which highlights the importance of accounting for active BS probability in small cell networks.
2. Energy Efficiency:
   • Unlike throughput, energy efficiency exhibits a non-monotonic behavior with varying BS density or number of transmit antennas. Initially, efficiency may rise due to better utilization of resources but may eventually decline if certain power consumption components exceed a threshold.
   • The paper provides critical insights into the conditions under which BS deployment can remain energy-efficient, identifying optimal density and antenna numbers for maximizing energy efficiency.

Theoretical and Practical Implications

The results have profound theoretical implications for designing small cell networks. They suggest that optimal configurations of BS density and antenna numbers can be achieved, contingent upon the specific characteristics of the network environment and power consumption models. Practically, these insights can guide network operators to strategically deploy infrastructure to balance throughput gains with energy consumption.

Future Research Directions

The framework opens several avenues for future research, particularly in extending the analysis to other multi-antenna transmission techniques such as MU-MIMO and examining the role of cooperative interference management strategies. Further exploration into heterogeneous network architectures using similar models can provide a deeper understanding of the trade-offs between densification, user experience, and energy consumption.

This paper stands as a significant contribution by providing both an analytical foundation and practical guidelines for the deployment and management of future small cell networks, underpinning efforts toward achieving scalable and energy-efficient wireless communication systems.