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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 a necessity for all DSL deployments, and serves a common interest of all involved DSL operators. Such rules were relatively simple for legacy deployments such as ADSL, SDSL and HDSL, but are far more complicated for VDSL2. This is mainly a consequence of deploying VDSL2 from remote locations (e.g. street cabinets), where it should coexist with legacy equipment deployed from the central office. This paper summarizes the signal limits essential for VDSL2 and discusses the reasoning behind them. Such limits can only be effective if they are tailored to underlying business needs, geographic characteristics of the network, the installed base of legacy equipment, loop characteristics etc. As such, access rules need to be country or region specific and cannot be copied blindly from neighbouring countries. |
