ZyXEL VES1724-56B2 User Guide - Page 97
VDSL Setup
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CHAPTER 9 VDSL Setup 9.1 VDSL Overview Very High Bit Rate DSL is an asymmetric version of DSL that is used as the final drop from a fiber optic junction point to nearby customers. VDSL lets an apartment or office complex obtain highbandwidth services using existing copper wires without having to replace the infrastructure with optical fiber. Like ADSL, VDSL can share the line with the telephone. Your Switch supports VDSL2 (Very High Speed Digital Subscriber Line 2) which is the second generation of the VDSL standard (which is currently denoted VDSL1). VDSL2 allows a frequency band of up to 30MHz and transmission rates of up to 100 Mbps in each direction. VDSL2 is defined in G.993.2. VDSL Parameters The following sections describe the VDSL parameters you configure in the following screens: •VDSL Template Setup (see Section 9.3 on page 104). •VDSL Alarm Template Setup (see Section 9.4 on page 121). PSD PSD (Power Spectral Density) defines the distribution of a VDSL line's power in the frequency domain. A PSD mask is a template that specifies the maximum allowable PSD for a line. Frequency Band Plan Each VDSL mode operates in a different frequency band allocation, resulting in different upstream and downstream speeds. Your VES switch automatically changes the band plan based on the loop condition and loop length. Band plans include an optional band (between 25 kHz and 276 kHz) controlled by "limit PSD mask". The optional band is used for upstream transmission which is to be negotiated during line initiation. A sample of limit PSD mask and associated frequency band is shown next. Table 26 Limit PSD Mask TRANSMISSION MODE G.993.2 Annex A G.993.2 Annex A G.993.2 Annex A G.993.2 Annex A CLASS MASK US0 MASK LIMIT MASK 998 EU-32 D-32 998 EU-36 D-48 998 EU-40 D-48 998 .... ... FREQUENCY BAND = 25 ~ 138 kHz = 25 ~ 155.25 kHz = 25 ~ 172.5 kHz = ... VES1724-56 User's Guide 97