Sleep mode management strategies for energy saving in cell-free wireless networks

Details

Supervisors

Louveaux, Jérôme ; Vandendorpe, Luc ; Oestges, Claude

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil électricien, à finalité spécialisée

Abstract

Wireless technologies have evolved rapidly over the past few decades. Data rates have increased dramatically, the number of connected devices has exploded and communication latency has been greatly reduced. Alongside these innovations, the share of the information and communication technology (ICT) sector in global electricity consumption has also risen sharply. Increasing the energy efficiency of wireless networks has therefore become a major concern. While major efforts have already been made in the development of the fifth generation of mobile telephony (5G), research is already focusing on future generations. Among the promising areas of research, cell-free networks have emerged as a means to increase energy efficiency and data rates compared to current cellular networks. In the cell-free paradigm, multiple Access Points (APs) are coordinated by centralising baseband processing in a shared central processing unit (CPU), allowing the APs to transmit coherently to user equipment (UE). The cooperation between the APs allows better interference management and a reduction of the spatial signal-to-noise ratio (SNR) variations. The aim of this work is to exploit the variations in traffic load throughout the day and put APs to sleep when possible to further reduce the energy consumption of cell-free networks. To do this, we study different cell-free (ASOs) presented in the literature, based on different time scales, and combine them with Advanced Sleep Modes (ASMs). These ASMs are incremental shutdowns of the hardware components of the APs, each with a different activation duration. A new hybrid ASO based on both statistical and instantaneous data is also developed to further exploit the ASMs. We then measure the impact of these ASOs on network power consumption and on the data rate experienced by network users. Next, the performance of the developed ASO is compared with that of small cells and Massive Multiple Input/Multiple Output (Ma-MIMO) cellular networks. The results show that the presented ASOs allow a significant reduction in the energy consumption of the studied network, with a low impact on the quality of service. In addition, the hybrid ASO offers greater flexibility in terms of the model used, making it more robust to technological changes. Finally, it is shown that cell-free networks with HASOs allow higher data rates with lower power consumption than cellular networks.