providing data rates as high as 24 Mbit/s downstream and 1 Mbit/s upstream depending on loop length. ADSL2+ can also be
used to reduce crosstalk because it provides the capability to use only tones between 1.1 MHz and 2.2 MHz, thus masking the
downstream frequencies below 1.1 MHz and associated interference. This is also referred to as Spectral Masking.
ADSL2+ Frequency Spectrum
VDSL2
Frequency configuration options of 8.5 MHz, 12 MHz, 17.7 MHz, and 30 MHz are set automatically depending on DSLAM
settings.
Note: Impulse Noise Protection (INP)
Electrical appliances and installations at customer premises often generate short bursts of noise of relatively
high amplitude. These bursts, called impulse noise, are electromagnetically coupled into the digital
subscriber line, degrading performance and in some cases disrupting service. The ADSL2/+ standard
introduced a parameter called Impulse Noise Protection (INP), that allows operators to select the maximum
impulse length that the DSL system can correct.
VDSL2 uses the same parameter and when implemented, an INP value between 2 and 16 can correct
errors from noise impulses ranging from 250µs to 3.75ms in length.
INP is a key feature in most IPTV video deployments and enables better Video QOS by minimizing the
effects of Impulse Noise.
The INP value for the interleaved channel can be set by the user and is expressed in symbols. For
example, an INP value of 1 means that 1 symbol can be corrected i.e. a burst of noise for 1 symbol
duration can be corrected without errors. One symbol equals 250µs, therefore an INP of 1 correlates to a
correction time of 250µs.
The Impulse Noise Protection (INP) or interleave depth is defined by the S and D parameters where:
S is the Interleave DMT symbols per FEC code word (1, 2, 4, 8, 16)
D is the Interleave depth (1, 2, 4, 8, 16, 32, 64)
Interleave delay can vary from 4.25 to 263.75 msec
MTTplus-523_e-manual, D07-00-117P RevA00
