Energy consumption of telecommunication access networks

1 Introduction The world of information and communications technologies (ICT) has changed rapidly in the last decade. The internet and its surrounding technologies became the most commonly used communication medium in people’s personal and working lives. It is critical for a vast range of services – gathering information, communication and entertainment are only the main functions. Key to accessing the internet and to using its services are broadband access networks. These access networks are based on different technologies, e.g. DSL or DOCSIS, and on separate infrastructures, such as the telephone or hybrid fibre coax network. Furthermore, completely new systems, like Fibre to the Home (FTTH), were developed. State of the art access technologies can provide data rates up to several hundred Megabit per second. These technologies are available and will be further developed. Despite the availability of highly sophisticated access technologies, the physical rollout is lagging behind. The telecommunication infrastructures in many countries were built decades ago and were not designed to transport digital data signals containing high frequencies. This leads to two different parameter sets, one for the physical infrastructure and a second for the new access technology, which uses the existing infrastructure. The problem is that these two parameter sets do not match. The telephone network for example has cable routes longer than a DSL signal can be transmitted. Consequently, the demanded resources cannot be provided to all customers. The infrastructure has to be updated or a completely new one (Fibre to the home, FTTH) has to be built, otherwise building broadband will come to a halt. The network operators and governments have accepted the task and two methods are primarily used today to update the infrastructure: 1. To update the telephone network, the length of the copper twisted pair wire has to be shortened. Therefore, so-called Outdoor DSLAMs could be installed. 2. To update the hybrid fibre coax network, more fibre nodes could be installed to shrink the service group size. If a completely new infrastructure is set up, a continuous fibre optic network is built. These networks are called Fibre to the Building/Home networks (FTTB/H) and connect the building/subscriber directly with the network operator’s Point of Presence (PoP) via a fibre optic wire. Theoretically, the update methods will also last into FTTB/H networks. This is, however, more a plan than a fact today. In the short-term, all of these methods are able to satisfy the data rates demanded by the subscribers. A question arises: Which of the methods should be selected? Two important decision-making criteria should be the power consumption as well as the energy efficiency of the different access technologies. However, this is not taken into account in the political and economic considerations so far. This study is intended to provide an initial impetus for the consideration and assessment of the energy requirements of different broadband access technologies. 3