| Popis: |
Spectral Management (SpM) involves managing an access network such that different systems can co-exist with each other. In relation to DSL systems, spectral management ensures that they can co-exist within the same cable. The use of spectral signal limits (specified via mandatory access rules) is necessary for all DSL deployments, and serves a common interest of all involved DSL operators. VDSL2 is a new technology, and can be deployed from remote locations such as street cabinets to shorten the loop to the home and thus increase the achievable bitrate. However, when all VDSL2 modems at customer premises transmit at full power, VDSL2 will only work well for customers that are close to the street cabinets. This situation can be improved significantly by reducing the transmit powers of nearby customers. This is called upstream power back-off, or simply UPBO. Such reductions can only be effective if they are tailored to underlying business needs, and on geographic and electrical characteristics of the network. These are all country or region specific, and should not be copied blindly from neighbouring countries. This paper shows how effective UPBO improves upstream bitrates for a variety of criteria, and how to define UPBO in an indisputable and implementation independent manner for specifying access rules. |
