Watson-SHDSL-Router-Manual.doc
Version 1.1-07
Watson SHDSL Router
Operating Manual
Revision: 2012-02-15
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3-11
3.5 DSL
3.5.1 Linerates and DSL sync rates
Watson EFM Plug-in modems support symmetrical DSL transmission as speci-
fied in ETSI TS 101 524 (SDSL) and ITU-T G.991.2 Annex B/G (G.SHDSL.bis).
The linecode used is either TC-PAM 16 or TC-PAM 32. With TC-PAM 16 the
supported linerate rates per pair are from 192 kbit/s to 3’840 kbit/s (3 - 60
timeslots of 64 kbit/s). TC-PAM 32 uses a 32-level linecode and allows a linerate
per pair from 768 kbit/s to 10’176 kbit/s (12 - 159 timeslots).
Figure 3-2: G.SHDSL.bis linerates
For certain linerates either TC-PAM 16 or TC-PAM 32 can be configured in the
modem. TC-PAM 16 has better DSL performance than TC-PAM 32. However
with linerates rates higher than 2’304 kbit/s (36 timeslots) and TC-PAM 16 the
symbol rate over the DSL becomes higher than what was specified in the original
version of ETSI TS 101 524. Higher symbol rates mean wider PSDs which in turn
can lead to higher interference to other DSL systems in the same cable binder,
e.g. ADSL, ADSL2, ADSL2+, VDSL2.
Beside the standards the Watson SHDSL router does as well support a 64- and
128-level linecode (TC-PAM 64 and TC-PAM 128). The number of timeslots per
pair when using TC-PAM 64 is from 160 to 199, the line rate when using TC-
PAM 64 is from 10’240 kbit/s to 12’736 kbit/s. The number of timeslots per pair
when using TC-PAM 128 is from 200 to 240, the line rate when using TC-PAM
128 is from 12’800 kbit/s to 15’360 kbit/s.
Please note that the linecodes PAM 64 and PAM 128 are much more sensitive
for interferences and noise and are therefore more difficult to apply in the real
network. For the same reason the line distances applicable for PAM 64 and PAM
128 are normally much shorter than with PAM 16 or PAM 32.
3.5.2 Multi-pair operation
Watson SHDSL router supports multi-pair operation. This allows aggregation of
individual DSL wire pairs for higher speeds or increased reach at a given speed.
Watson SHDSL router supports two different multi-pair aggregation methods: the
IEEE 802.3ah EFM PAF and the ETSI / ITU-T SHDSL M-pair mode.
EFM PAF allows configuring different linerate on the different DSL wire pairs with
a maximum linerate ratio of 1 to 4. It is also resilient to DSL wire pair failure. If
one pair fails the link is maintained using the other pairs. The data service is run-
ning at a lower speed, but is kept uninterrupted.
16 TC
-PAM
16 TC -PAM
32 TC -PAM
G.SHDSL, ETSI TS 101 524
5'696
Linerate
kBps
192 768
3'840
2'304
G.SHDSL.bis, e -SDSL
