UIT - Secteur de la normalisation des télécommunications
ITU - Telecommunication Standardization Sector
UIT - Sector de Normalización de las Telecomunicaciones
Study Period 1997-2000
Commission d' études 

Study Group
 16
Comisión de Estudio 

Contributi on tardive 

Delayed Contributi on  D.xxx
Contribuci ón tardía 

Geneva, 7 - 18 February 2000
Texte disponible seulement en 

Text available only in
 E
Texto disponible solamente en 

Question(s): 23/16
SOURCE*:
3Com Corp., Motorola, Lucent Technologies
TITLE:
Phase0/Phase1 Quick Connect proposal for Recommendation V.92
___________________
Abstract
We propose simple Quick Connect Phase1/Phase2 procedures for use in ITU Recommendation
V.92.
* Contact:
Vladimir Parizhsky
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Tel:
+1 (212) 760-3964
Fax:
+1 (212) 629-9801
E-mail: [email protected]
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1. Introduction
The intent of this paper is to present the simplest possible Phase0/Phase1 Quick Connect (QC)
procedure. We assume it is desirable to interrupt V.8bis and V.8 in Phase0. We also would like to
eliminate L1/L2 for both Analogue and Digital modems and Round Trip Delay (RTD) measurement
from Analogue to Digital modem direction. We keep the rest of the procedures as close to V.90 as
we can. We also assume the following:
V.34 and V.90 are subsets of V.92 as far as Phase1/Phase2 goes. This is similar to V.34
being a subset of V.90 up to Phase 3. So if QC is defined for V.92 it is automatically defined for
V.34 and V.90 as a fallback.
We intend to signal V.92 mode through INFO0 to avoid messing with V.8. QC is
mandatory in V.92 so no special signaling is needed to signal QC, in addition to V.92.
2.
Phase0/Phase1 Proposal
1 Sec.
APCM
CMshort
DPCM
ANSam
CM
JJ
INFO0a
INFO0d
A
B
A\
INFO1a
B\
Fig. 1 Short Restart Phase 1 and 2 – without V.8bis:
1 Sec.
APCM
DPCM
QC
CMshort
CRe
ANSam
Fig. 2 Short Restart Phase 1 – with V.8bis:
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Phase3
Phase3
-3-
1 Sec.
200ms
APCM
QC
DPCM
QC
CMshort
CRe
ANSam
Fig. 3 Short Restart Phase 1 – with V.8bis and recovery:
a.b
Short restart signals for the analogue modem
a.b.1
QC
Signal QC is a 1529 Hz tone transmitted for 100 ms. The tone may be repeated after a 200 ms
silence.
Due to some network echo chancellors, the DPCM may not receive the first QC properly. If the
APCM waits 200 ms and then resends QC, the latter QC should get through. This will also allow
the procedure to work with echo suppressers.
a.b.2
CMshort
Signal CMshort is a sequence of bits transmitted using V21(L) modulation. The bits consist of 10bit frames using V.8-type formatting. CMshort is only transmitted once, and is generally followed
by transmission of CM. Only the first 20 bits are required to be transmitted.
Bit position
Content
Description
0:9
1111111111
V.8 preamble
10:19
0101010101
CMshort synchronisation
20:29
0100000111
V.8 call function
30:39
0111001011
V.90 availability category
40:49
0101100001
PSTN access category
The DPCM could detect CMshort only based on the first 20 bits, as the synchronisation bits are
unique.
Analogue modem has to remember that it connected to the same V.92 modem before the current
call. So during the current call analogue modem issues CMshort followed by continuous CM. If
Digital modem misses CMshort, the pair goes through the normal V.8 V.92 connect.
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a.b.3
INFO0a , INFO1a
See V.90, V.92
a.c
Short restart signals for the digital modem
a.c.1
ANSam
See V.8
a.c.2
JJ
Signal JJ consists of ten ONEs followed by three consecutive octets of all ZEROs with start and
stop bits, modulating V.21(H) at 300 bit/s.
JJ is intended to look like CJ, but since CJ is only transmitted after CM it doesn’t require a
preamble.
If analogue modem misses JJ it has to see silence. Silence will be equivalent to JJ because
ANSam producing modem can't avoid sending JM. So JJ or silence indicates QC entry. Only V.8
continuation (JM) declines it.
a.c.3
INFO0d
See V.90, V.92
____________________
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