A.2 False Z sequence detection
3GPP48.020Rate adaption on the Base Station System - Mobile-services Switching Centre (BSS - MSC) interfaceRelease 17TS
The Framing Pattern Substitution algorithm presented in subclause 10.2 ensures sure that all the Z sequences found in the original sub frame are removed, but it shall be checked that the transformations performed do not introduce new unwanted Z sequences.
The goal of this subclause is to show that the transformed sub frame does not contain new Z sequences introduced by the algorithm itself.
The coding of the ZSP is the key point to avoid such an emulation. The different cases are considered below.
1: Sequence ZSP
The worst case is when the address is equal to 1:
|
1 |
C |
A0 |
A1 |
A2 |
A3 |
A4 |
1 |
|
1 |
0 |
0 |
0 |
0 |
0 |
1 |
1 |
There is a maximum of 5 zeroes.
2: Sequence Di / ZSP.
By definition, a data block always ends up with a one (except the last one of the message) and the ZSP always starts with a 1.
3: Sequence ZSP / Di
ZSP always ends up with a 1 and Di has a maximum of 7 zeroes : it is not possible to find 16 zeroes in a row.
4:Sequence Di / Dj
Di is not the last data block of the message.
As already mentioned, Di ends up with a one (except the last one) : this is the same case as 3.
5: Sequence Zi / D or D / Zi
This case only occurs when there is no substitution. In this case, the Zi bit close to the D field is always a one: this does not change the number of zeroes in sequence.
6: Sequence last Di / new framing pattern
The last D sequence can end up with up to 7 zeroes, followed by the 16 zeroes of the next frame.
There is anyhow no ambiguity, when considering that the framing pattern is made up of 16 zeroes followed by a one.
7: Sequence last Di / Z bit of the next sub frame
The last D sequence can end up with up to 7 zeroes, followed in the worst case by Z=0 and then a ZSP. As a ZSP starts with a one, this makes a maximum of 8 zeroes in a row.
8: Sequence ZSP / ZSP (not shown on the figure)
This case arrives when the original message has at least 16 zeroes in a row.
As the ZSP element always starts and ends up with a one, this always induces two consecutive ones.
Annex B (informative):
Change History
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Change history |
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Date |
TSG # |
TSG Doc. |
CR |
Rev |
Subject/Comment |
Old |
New |
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s27 |
A005 |
Synchronisation |
5.3.0 |
7.0.0 |
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s29 |
A006 |
Introduction of EDGE channel codings into the specifications |
7.0.0 |
8.0.0 |
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s30 |
A007 |
Asymmetric channel coding |
8.0.0 |
8.1.0 |
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09-2000 |
TSG#09 |
NP-000551 |
A008 |
1 |
32 kbit/s UDI/RDI multimedia in GSM |
8.1.0 |
8.2.0 |
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12-2000 |
TSG#10 |
NP-000604 |
A009 |
Removal of 1200/75 bit/s data rate and clean-up |
8.2.0 |
8.3.0 |
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03-2001 |
TSG#11 |
NP-010040 |
A013 |
Correction of downgrading procedure for HSCSD |
8.3.0 |
8.4.0 |
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03-2001 |
TSG#11 |
Upgraded to Release 4 [08.20 -> 48.020] |
8.4.0 |
4.0.0 |
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12-2001 |
TSG#14 |
NP-010604 |
001 |
1 |
Terminology clarifications requested by TSG GERAN |
4.0.0 |
5.0.0 |
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09-2002 |
TSG#17 |
NP-020405 |
002 |
Correction of Rate Adaptation Functions and removal of S Reference Point in MS |
5.0.0 |
5.1.0 |
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12-2002 |
TSG#18 |
NP-020617 |
003 |
4 |
CS Data Services (including HSCSD and EDGE) for GERAN Iu mode |
5.1.0 |
5.2.0 |
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12-2004 |
CN#26 |
Upgraded to v6.0.0 |
5.2.0 |
6.0.0 |
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06-2007 |
CT#36 |
Upgraded to v7.0.0 |
6.0.0 |
7.0.0 |
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12-2008 |
CT#42 |
Upgraded to v8.0.0 |
7.0.0 |
8.0.0 |
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12-2009 |
CT#46 |
Automatic upgrade from previous Release |
8.0.0 |
9.0.0 |
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03-2011 |
CT#51 |
Automatic upgrade from previous Release version 9.0.0 |
9.0.0 |
10.0.0 |
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03-2011 |
CT#51 |
Correction of heading and numbering made by MCC |
10.0.0 |
10.0.1 |
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09-2012 |
CT#57 |
Automatic upgrade from previous Release version 10.0.1 |
10.0.1 |
11.0.0 |
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2014-10 |
Automatic upgrade from previous Release |
11.0.0 |
12.0.0 |
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2015-12 |
Automatic upgrade from previous Release |
12.0.0 |
13.0.0 |
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Change history |
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Date |
TSG # |
TSG Doc. |
CR |
Rev |
Cat |
Subject/Comment |
New |
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2017-03 |
CT#75 |
Automatic upgrade from previous Release |
14.0.0 |
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2018-06 |
SA#80 |
– |
– |
– |
Automatic upgrade from previous Release |
15.0.0 |
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2020-07 |
SA#88e |
– |
– |
– |
Update to Rel-16 version (MCC) |
16.0.0 |
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2022-03 |
SA#95e |
– |
– |
– |
Update to Rel-17 version (MCC) |
17.0.0 |
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