ETSI TR 145 902 V13.0.0 (2016-01)

ETSI TR 1145 902 V13.0.0 (201616-01)






TECHNICAL REPORT
Digital cellular telecocommunications system (Phahase 2+);
Flexibxible Layer One (FLO)
(3GPP TR 45.9.902 version 13.0.0 Release 13 13)

R
GLOBAL SYSTTEME FOR
MOBILE COMMUUNNICATIONS

---------------------- Page: 1 ----------------------
3GPP TR 45.902 version 13.0.0 Release 13 1 ETSI TR 145 902 V13.0.0 (2016-01)



Reference
RTR/TSGG-0145902vd00
Keywords
GSM
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE

Tel.: +33 4 92 94 42 00  Fax: +33 4 93 65 47 16

Siret N° 348 623 562 00017 - NAF 742 C
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° 7803/88

Important notice
The present document can be downloaded from:
http://www.etsi.org/standards-search
The present document may be made available in electronic versions and/or in print. The content of any electronic and/or
print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any
existing or perceived difference in contents between such versions and/or in print, the only prevailing document is the
print of the Portable Document Format (PDF) version kept on a specific network drive within ETSI Secretariat.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at
http://portal.etsi.org/tb/status/status.asp
If you find errors in the present document, please send your comment to one of the following services:
https://portal.etsi.org/People/CommiteeSupportStaff.aspx
Copyright Notification
No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying
and microfilm except as authorized by written permission of ETSI.
The content of the PDF version shall not be modified without the written authorization of ETSI.
The copyright and the foregoing restriction extend to reproduction in all media.

© European Telecommunications Standards Institute 2016.
All rights reserved.

TM TM TM
DECT , PLUGTESTS , UMTS and the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members.
TM
3GPP and LTE™ are Trade Marks of ETSI registered for the benefit of its Members and
of the 3GPP Organizational Partners.
GSM® and the GSM logo are Trade Marks registered and owned by the GSM Association.
ETSI

---------------------- Page: 2 ----------------------
3GPP TR 45.902 version 13.0.0 Release 13 2 ETSI TR 145 902 V13.0.0 (2016-01)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (https://ipr.etsi.org/).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI 3rd Generation Partnership Project (3GPP).
The present document may refer to technical specifications or reports using their 3GPP identities, UMTS identities or
GSM identities. These should be interpreted as being references to the corresponding ETSI deliverables.
The cross reference between GSM, UMTS, 3GPP and ETSI identities can be found under
http://webapp.etsi.org/key/queryform.asp.
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI

---------------------- Page: 3 ----------------------
3GPP TR 45.902 version 13.0.0 Release 13 3 ETSI TR 145 902 V13.0.0 (2016-01)
Contents
Intellectual Property Rights . 2
Foreword . 2
Modal verbs terminology . 2
Foreword . 5
Introduction . 5
1 Scope . 6
2 References . 6
3 Definitions, symbols and abbreviations . 6
3.1 Definitions . 6
3.2 Abbreviations . 7
4 Motivation . 8
5 Requirements . 8
6 Overview of FLO . 9
6.1 General . 9
6.2 Principles of FLO . 9
6.3 Evolution from Release 5 . 9
6.4 Limitations . 10
6.5 Protocol architecture. 10
6.5.1 Iu mode . 10
6.5.2 A/Gb mode. 11
6.5.3 TBF configuration principles . 11
7 Layer 1 for FLO . 11
7.1 CRC Attachment . 12
7.2 Channel Coding . 13
7.3 Rate Matching . 13
7.4 Transport Channel Multiplexing . 16
7.4a Inband signalling bits . 16
7.5 Transport Format Combination Identifier (TFCI) . 16
7.6 Interleaving. 17
7.7 Signalling on HR Channels . 18
8 Layer 2 for FLO . 19
8.1 Protocol architecture in Iu mode . 19
8.1.1 General . 19
8.1.2 RLC protocol . 20
8.1.3 MAC protocol . 20
8.2 Protocol architecture in A/Gb mode . 20
8.3 RLC/MAC block structure . 20
8.3.1 General . 20
8.3.2 RLC/MAC blocks for control message transfer. 21
8.3.2.1 Downlink RLC/MAC control block format . 21
8.3.2.2 Uplink RLC/MAC control block format . 21
8.3.3 RLC/MAC blocks for data transfer . 21
8.3.3.1 Downlink RLC/MAC block for data transfer . 21
8.3.3.1.1 RLC unacknowledged mode . 21
8.3.3.1.2 RLC acknowledged mode . 22
8.3.3.1.3 RLC transparent mode . 22
8.3.3.2 Uplink RLC/MAC block for data transfer . 22
8.3.3.2.1 RLC unacknowledged mode . 22
8.3.3.2.2 RLC acknowledged mode . 22
8.3.3.2.3 RLC transparent mode . 23
ETSI

---------------------- Page: 4 ----------------------
3GPP TR 45.902 version 13.0.0 Release 13 4 ETSI TR 145 902 V13.0.0 (2016-01)
8.4 Ciphering in Iu mode . 23
8.4.1 General . 23
8.4.2 Parameters settings . 23
8.4.2.1 RLC non-transparent mode . 23
8.4.2.2 RLC transparent mode . 23
8.4.2.3 RLC/MAC control messages . 24
8.5 TFC Selection . 24
8.5.1 TFC selection in the uplink . 24
8.5.2 TFC selection in the downlink . 24
8.6 Ciphering in A/Gb mode . 24
9 Layer 3 for FLO . 25
9.1 In Iu mode. 25
9.2 In A/Gb mode . 25
9.3 Transport and physical channel configuration . 25
9.4 Calculated Transport Format Combination . 26
9.4.1 Definition . 26
9.4.2 Example . 27
9.5 TFC for Signalling. 28
9.6 TBF configuration . 28
10 Testing of FLO . 28
11 Impact on Specifications . 29
Annex A (informative): Block Codes for the TFCI . 30
Annex B (informative): Header fields . 32
B.1 Payload Type (PT) field . 32
B.2 Polling (P) bit . 32
B.3 Segmentation (S) bit . 32
B.4 Reduced Block Sequence Number (RBSN) bit . 32
B.5 Radio Transaction Identifier (RTI) field . 32
B.6 Temporary Flow Identity (TFI) field . 33
B.7 Block Sequence Number (BSN) field . 33
B.7.1 General . 33
B.7.2 RLC unacknowledged mode . 33
B.7.3 RLC acknowledged mode . 33
B.8 Split Block Indicator (SPB) field . 33
B.9 Stall Indicator (SI) field . 33
B.10 Extension (E) bit . 33
B.11 Length Indicator (LI) field. 34
Annex C: Change history . 35
History . 36

ETSI

---------------------- Page: 5 ----------------------
3GPP TR 45.902 version 13.0.0 Release 13 5 ETSI TR 145 902 V13.0.0 (2016-01)
Foreword
rd
This Technical Report has been produced by the 3 Generation Partnership Project (3GPP).
The contents of the present document are subject to continuing work within the TSG and may change following formal
TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an
identifying change of release date and an increase in version number as follows:
Version x.y.z
where:
x the first digit:
1 presented to TSG for information;
2 presented to TSG for approval;
3 or greater indicates TSG approved document under change control.
y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections,
updates, etc.
z the third digit is incremented when editorial only changes have been incorporated in the document.
Introduction
A new type of physical layer is proposed for the GSM/EDGE Radio Access Network (GERAN): the flexible layer one
(FLO). The main advantage of FLO is that the configuration of the physical layer (e.g. channel coding and interleaving)
is specified at call setup. This means that the support of new services such as IP Multimedia Subsystem (IMS) services
can be handled smoothly without having to specify new coding schemes in each release.
Through several enhancements such as reduced granularity and flexible interleaving, the radio bearers offered by FLO
would not only fulfil the IMS requirements in terms of flexibility and performance, but also greatly improve the link
level performance of real-time IMS services compared to GERAN Release 5.
The objective of this TR is to provide an overview of FLO, its architecture and study the impacts it has on the GERAN
radio protocol stack.
ETSI

---------------------- Page: 6 ----------------------
3GPP TR 45.902 version 13.0.0 Release 13 6 ETSI TR 145 902 V13.0.0 (2016-01)
1 Scope
The present document provides an overview of the flexible layer one, its architecture and studies the impacts it has on
the GERAN radio protocol stack.
2 References
The following documents contain provisions, which, through reference in this text, constitute provisions of the present
document.
• References are either specific (identified by date of publication, edition number, version number, etc.) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including
a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same
Release as the present document.
[1] 3GPP TR 21.905: 'Vocabulary for 3GPP Specifications'.
[2] 3GPP TS 22.101, 'Service Principles'.
[3] 3GPP TS 22.228, 'Service requirements for the IP Multimedia Core Network Subsystem'.
[4] 3GPP TS 23.107, 'QoS Concept and Architecture'.
[5] 3GPP TS 23.228, 'IP Multimedia Subsystem'.
[6] 3GPP TS 25.201, 'Physical layer - General description'.
[7] 3GPP TS 25.212, 'Multiplexing and channel coding (FDD)'.
[8] 3GPP TS 25.331, 'RRC Protocol Specification'.
[9] 3GPP TS 32.201, 'Specification of the 3GPP Confidentiality and Integrity Algorithms'.
[10] 3GPP TS 44.018: 'Radio Resource Control protocol'.
[11] 3GPP TS 44.118: 'Radio Resource Control protocol, Iu mode'.
[12] 3GPP TS 44.060: 'Radio Link Control/Medium Access Control protocol'.
[13] 3GPP TS 44.160: 'Radio Link Control/Medium Access Control protocol, Iu mode'.
[14] 3GPP TS 45.002: 'Multiplexing and multiple access on the radio path'.
[15] 3GPP TS 45.003: 'Channel Coding'.
[16] 3GPP TS 45.005: 'Radio transmission and reception'.
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply.
Active Transport Channel: a transport channel is active during a TTI if it carries a transport block.
ETSI

---------------------- Page: 7 ----------------------
3GPP TR 45.902 version 13.0.0 Release 13 7 ETSI TR 145 902 V13.0.0 (2016-01)
Dynamic attributes: for one transport channel, the values of the dynamic attributes are different among transport
formats. They are configured by Layer 3 and can change on a TTI basis under the control of the MAC sublayer.
Empty Transport Format: a transport format such that no transport block is carried over the transport channel (i.e. the
transport channel is inactive).
Empty Transport Format Combination: a transport format combination that is made up only of empty transport
formats.
Inactive Transport Channel: a transport channel is inactive during a TTI if it does not carry a transport block (i.e. the
transport block size is zero).
Radio Frame: The result of applying rate matching to a transport block along with its associated CRC that have first
been channel encoded.
Radio Packet: The set of one or more radio frames together with the applicable coded TFCI that form the volume of
payload that can be transmitted on a basic physical subchannel for any given TTI.
Semi-static attributes: for one transport channel, the values of the semi-static attributes are common to all transport
formats. They are configured by Layer 3 and can only be changed by Layer 3 signalling.
Transport Block: block exchanged on a transport channel between the physical layer and the MAC sublayer.
Transport Channel: SAP between the physical layer and the MAC sublayer.
Transport Format: configuration of a transport channel, including for instance channel coding, CRC size, etc.
Transport Format Combination: allowed combination of transport format(s) of the different transport channels that
are multiplexed together on a basic physical subchannel.
Transport Format Combination Indicator: layer one header that indicates the transport format combination that has
been selected for each radio packet.
Transport Format Combination Set: set of allowed transport format combinations on a basic physical subchannel.
Transport Format Indicator: index identifying a particular transport format within the transport format set.
Transport Format Set: set of all transport formats defined for a particular transport channel.
Transmission Time Interval: rate at which transport blocks are exchanged between the physical layer and the MAC
sublayer on a transport channel.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ADCH Associated Dedicated CHannel
CCTrCH Coded Composite Transport CHannel
CDCH Control-plane Dedicated CHannel
CTFC Calculated Transport Format Combinations
DCH Dedicated CHannel
FLO Flexible Layer One
GERAN GSM/EDGE Radio Access Network
IMS IP Multimedia Subsystem
MAC Medium Access Control
QoS Quality of Service
PDU Protocol Data Unit
RAN Radio Access Network
RLC Radio Link Control
RRC Radio Resource Control
RT Real Time
SDU Service Data Unit
SAP Service Access Point
TB Transport Block
ETSI

---------------------- Page: 8 ----------------------
3GPP TR 45.902 version 13.0.0 Release 13 8 ETSI TR 145 902 V13.0.0 (2016-01)
TBF Temporary Block Flow
TF Transport Format
TFI Temporary block Flow Identity
TFS Transport Format Set
TFIN Transport Format INdicator
TFC Transport Format Combination
TFCI Transport Format Combination Indicator
TFCS Transport Format Combination Set
TrCH Transport Channel
TTI Transmission Time Interval
UDCH User-plane Dedicated CHannel
UTRAN Universal Terrestrial Radio Access Network

Other abbreviations used in the present document are listed in 3GPP TR 21.905.
4 Motivation
The need for a flexible layer one for the Release 6 of GERAN is driven by the introduction of IMS services. For an
efficient support of IMS services, requirements are set on the radio bearer service of the RAN (see 3GPP TS 22.101,
3GPP TS 22.228, 3GPP TS 23.228 and 3GPP TS 23.107):
- the radio bearers should be flexible enough to efficiently deploy any IP multimedia applications;
- the radio bearers should allow the transport of several flows in parallel (e.g. text and video);
- the radio bearers should satisfy the user in a spectral efficient manner;
- the radio bearer should support the UMTS QoS concept and architecture.
So as to fulfil these requirements in an efficient manner, a flexible layer one is needed. Thanks to the flexible layer one
optimised support of real time IMS services is made possible in GERAN.
5 Requirements
The flexible layer one should:
- fulfil most of the IMS requirements in terms of radio bearer service attributes;
- support the multiplexing of parallel flows on to a basic physical subchannel;
- provide an optimisation of spectral efficiency through the support of different interleaving depths, unequal error
protection/detection, reduced channel coding rate granularity and support of 8PSK and GMSK modulations;
- provide an efficient support of real time IMS services;
- be applicable to both modes of operation: A/Gb mode and Iu mode;
- minimize the impacts on the radio protocols;
- minimize the overhead introduced by the radio protocol stack;
- not introduce an unfeasible number of test configurations;
- be future proof;
- within reason, be compatible with legacy transceiver implementations.
ETSI

---------------------- Page: 9 ----------------------
3GPP TR 45.902 version 13.0.0 Release 13 9 ETSI TR 145 902 V13.0.0 (2016-01)
6 Overview of FLO
6.1 General
In GERAN Release 5, the MAC sublayer is responsible for the mapping between the logical channels (traffic or control
channels) and the basic physical channels (see 3GPP TS 45.002). The logical channels are the channels the physical
layer offers to the MAC sublayer. Until now these logical channels and the mapping to the basic physical channel have
been fully specified in 3GPP TS 45.002.
A different approach has been taken in UTRAN, where instead of providing logical channels the physical layer offers
Transport Channels (TrCH), which can be used by the MAC sublayer (see 3GPP TS 25.201). A transport channel is
used to transmit one data flow with a given QoS over the radio interface. A number of transport channels can be active
at the same time and multiplexed at the physical layer. The transport channels are configured at call setup by the
network.
With FLO, the concept of transport channels used in UTRAN can be reused in GERAN i.e. the physical layer offers one
or several transport channels to the MAC sublayer.
6.2 Principles of FLO
With FLO, the physical layer of GERAN offers one or several transport channels to the MAC sublayer. Each of these
transport channels can carry one data flow providing a certain Quality of Service (QoS). A number of transport channels
can be multiplexed and sent on the same basic physical subchannel at the same time.
The configuration of a transport channel i.e. the number of input bits, channel coding, interleaving etc. is denoted the
Transport Format (TF). As in UTRAN, a number of different transport formats can be associated to o
...