Energy consumption of telecommunication access networks

5 Access network modelling 5.1 DSL-Modelling Like all DSL technologies, VDSL2-Vectoring has severe length restrictions. As Figure 10 shows, the usable data rate drops along the copper cable’s length so that the minimum data rate of 50 Mbit/s can be delivered only over a few hundred metres. The telephone infrastructure, which is used by all DSL technologies, has by far longer cable lines. As a result, the demanded data rate is not available for every subscriber. Figure 10: The graph shows the achievable data rate of the different DSL technologies respective to the reach in a simplified manner. To provide the minimum data rate to all subscribers, the copper cable lines have to be shortened. This is done by installing new DSLAMs in the field close to the customers – typically in the existing street cabinets. In most rural areas however, installing new DSLAMs in the existing street cabinets is not enough to deliver the minimum data rate to all subscribers. Typically about 10% – 15% of the connections will not be reached. In order to provide the required data rate to the last 10% – 15% of the rural subscribers, new street cabinets with DSLAMs have to build. All street cabinets, existing and new ones, with active DSLAM components need a power and fibre connection, which have to be built too. To determine the power consumption of a VDSL2- Vectoring network, which is based on the existing telephone infrastructure and delivers the minimum data rate of 50 Mbit/s to every subscriber, the number of active network components has to be calculated. The calculation is carried out as follows: 1. Determine all subscribers who are provided directly from the central offices (number of central offices is known). 2. Determine all subscribers who can be supplied by installing DSLAMs into the existing street cabinets (number of existing street cabinets is known). 3. Determine new street cabinet locations which reach a maximum number of new subscribers within a certain radius until all remaining connections are assigned to a new street cabinet. (To determine the radius for the georeferenced analysis, over 235,000 data sets were statistically evaluated. A data set includes information about the actual cable length between a connection point and the street cabinet which it is assigned to, the linear distance between a connection point and its street cabinet and the achievable data rate with ADSL2+, VDSL2 and VDSL2-Vectoring). 4. Assign every street cabinet to a size class based on the number of subscribers. After carrying out the steps one to four, the number and size of the active network elements for the VDSL2- Vectoring network in this specific region is known. The next step is to assign power parameters to every network element so that the overall power consumption can be estimated. 15