Energy Consumption and Environmental Implications of Wired Access Networks

Al-Ghathian Al-Ghathian

doi:10.3844/ajeassp.2011.531.539

Abstract

Problem statement: Wired broadband Internet access can be realized using various technologies, configurations and protocols. It is widely deployed and able to provide both high data rates and high reliability. These features are of strong importance for many advanced applications. Since the number of broadband subscribers worldwide grows exponentially, the power efficiency of access networks becomes increasingly important. Approach: The aim of this study is to study power consumption of different wired broadband access technologies including both those already widely used and those which are state-of-the-art, but not yet widely deployed. For this purpose, we developed a model for evaluating energy efficiency of wired access networks. The model is presented and applied to study energy efficiency of various access networks such as Hybrid Fiber Coax (HFC), Digital Subscriber Line (DSL), 1 and 10 Gbit/s point-to-point ethernet and Passive Optical Networks (1G-PON and 10G-PON). The metric for energy efficiency we used in this study is energy consumed per bit transmitted. Results: Results of the comparative study on energy efficiency of different access networks are shown and discussed. Additionally, we estimated environmental implications of different access options by means of reductions in Green House Gas (GHG) emissions caused by the electricity consumption of access network infrastructure. Conclusion: We found out that high-speed optical access technologies providing up to 10 Gbit/s per user have the potential to achieve the highest energy efficiency when assuming future broadband Internet access and broad use of advanced services and applications. However, for lower access data rates, 1G-PONs are the most energy efficient access options. Coper-based access technologies provide generally lower energy efficiency than the fiber based solutions. For transferring a large amount of data and when network equipment is switched off during its inactivity times, optical access technologies have the highest potential to reduce GHG emissions caused by the electricity consumption of access network infrastructure.

Highlights

Nowadays, the majority of broadband access subscribers have either a wired access over telephone lines, in most cases a version of Digital Subscriber Line (DSL), or a wireless access such as WiMAX, WiFi, GSM or UMTS
We considered two scenarios; one with unlimited uplink to the metropolitan area network and another one with an uplink limited to 320 Gbit/s
To-the-Node (FTTN) configuration using ADSL2+, VDSL or Hybrid Fiber Coax (HFC) shows the lowest efficiency, excepting the case in which a large number of subscribers are connected to the central office that has a limited uplink capacity

Summary

INTRODUCTION

The majority of broadband access subscribers have either a wired access over telephone lines, in most cases a version of Digital Subscriber Line (DSL), or a wireless access such as WiMAX, WiFi, GSM or UMTS. The obtained results are account the effect of reducing the data rate with shown in the “Results” The “Discussion” addresses increasing the transmission distance Since both xDSL possible environmental impact of the considered access and HFC are assumed to be implemented in the FTTN technolgoes. Please note that an all-copper solution, i.e. when electrical signals are transmitted over copper cables directly from central office to user premises, would result in significantly reduced data rates for long distances in case of xDSL and in a much lower energy efficiency of copper-based access technologies. In case of the widely deployed HFC and xDSL systems, we created a data base of network elements, i.e., Cable Modem Termination Systems (CMTSs), DSLAMs and DSL/HFC modems and calculated mean values that we used for the calculation of power efficiency.

10 G Ethernet

Findings

CONCLUSION