ETSI TR 103 219 V1.1.1 (2015-04)

Speech and multimedia Transmission Quality (STQ); Quality of Service aspects of voice communication in an LTE environment

DTR/STQ-00198m

General Information

• Status: Published
• Publication Date: 20-Apr-2015
• Technical Committee: STQ MOBILE - STQ Mobile
• Current Stage: 12 - Completion
• Due Date: 28-Apr-2015
• Completion Date: 21-Apr-2015

Standards Content (Sample)

ETSI TR 103 219 V1.1.1 (2015-04)






TECHNICAL REPORT
Speech and multimedia Transmission Quality (STQ);
Quality of Service aspects of voice communication
in an LTE environment

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2 ETSI TR 103 219 V1.1.1 (2015-04)



Reference
DTR/STQ-00198m
Keywords
CSFB, QoS, VoLTE
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3 ETSI TR 103 219 V1.1.1 (2015-04)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Abbreviations . 7
4 Circuit-Switched Fall Back . 7
4.1 General overview of CSFB . 7
4.2 Amendments to existing QoS parameters . 8
4.2.1 CSFB Call Setup Failure Ratio [%] . 8
4.2.1.1 Preconditions . 8
4.2.1.2 Abstract definition . 8
4.2.1.3 Abstract equation . 9
4.2.1.4 Trigger points . 9
4.2.2 CSFB Call Setup Time [s] . 9
4.2.2.1 Preconditions . 9
4.2.2.2 Abstract definition . 9
4.2.2.3 Abstract equation . 9
4.2.2.4 Trigger points . 10
4.3 Proposed new QoS parameters in the context of CSFB . 10
4.3.1 Overview . 10
4.3.2 CSFB Failure Ratio [%] - Calling party. 10
4.3.2.1 Preconditions . 10
4.3.2.2 Abstract definition . 10
4.3.2.3 Abstract equation . 10
4.3.2.4 Trigger points . 11
4.3.3 CSFB Time [s] - Calling party . 11
4.3.3.1 Preconditions . 11
4.3.3.2 Abstract definition . 11
4.3.3.3 Abstract equation . 11
4.3.3.4 Trigger points . 11
4.3.4 CSFB Failure Ratio [%] - Called party . 12
4.3.4.1 Preconditions . 12
4.3.4.2 Abstract definition . 12
4.3.4.3 Abstract equation . 12
4.3.4.4 Trigger points . 12
4.3.5 CSFB Time [s] - Called party . 12
4.3.5.1 Preconditions . 12
4.3.5.2 Abstract definition . 12
4.3.5.3 Abstract equation . 13
4.3.5.4 Trigger points . 13
4.3.6 CSFB Return to LTE Failure Ratio [%] . 13
4.3.6.1 Preconditions . 13
4.3.6.2 Abstract definition . 13
4.3.6.3 Abstract equation . 13
4.3.6.4 Trigger points . 13
4.3.7 CSFB Return to LTE Time [s] . 14
4.3.7.1 Preconditions . 14
4.3.7.2 Abstract definition . 14
4.3.7.3 Abstract equation . 14
4.3.7.4 Trigger points . 14
ETSI

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4 ETSI TR 103 219 V1.1.1 (2015-04)
5 VoLTE (IMS based) . 14
5.1 Overview . 14
5.2 Amendments to existing QoS parameters . 16
5.2.1 VoLTE Session Setup Failure Ratio [%] . 16
5.2.1.1 Preconditions . 16
5.2.1.2 Abstract definition . 16
5.2.1.3 Abstract equation . 16
5.2.1.4 Trigger points . 16
5.2.2 VoLTE Session Setup Time [s] . 16
5.2.2.1 Preconditions . 16
5.2.2.2 Abstract definition . 17
5.2.2.3 Abstract equation . 17
5.2.2.4 Trigger points . 17
5.2.3 VoLTE Session Cut-off Ratio [%] . 17
5.2.3.1 Preconditions . 17
5.2.3.2 Abstract definition . 17
5.2.3.3 Abstract equation . 17
5.2.3.4 Trigger points . 18
5.3 Proposed new QoS parameters in the context of VoLTE . 18
5.3.1 Overview . 18
5.3.2 IMS Registration Success Ratio [%] . 18
5.3.2.1 Preconditions . 18
5.3.2.2 Abstract definition . 19
5.3.2.3 Abstract equation . 19
5.3.2.4 Trigger points . 19
5.3.3 IMS Registration Time [s] . 19
5.3.3.1 Preconditions . 19
5.3.3.2 Abstract definition . 19
5.3.3.3 Abstract equation . 19
5.3.3.4 Trigger points . 20
5.3.4 SRVCC Success Ratio [%] . 20
5.3.4.1 Preconditions . 20
5.3.4.2 Abstract definition . 20
5.3.4.3 Abstract equation . 20
5.3.4.4 Trigger points . 20
5.3.5 SRVCC Time [s] . 20
5.3.5.1 Preconditions . 20
5.3.5.2 Abstract definition . 21
5.3.5.3 Abstract equation . 21
5.3.5.4 Trigger points . 21
History . 22


ETSI

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5 ETSI TR 103 219 V1.1.1 (2015-04)
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 (http://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 Technical Committee Speech and multimedia Transmission
Quality (STQ).
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.
Introduction
LTE networks are a reality in many markets. CS voice interworking is one of the most crucial points in many networks
in Europe. Voice services used on LTE enabled handsets in an LTE environment bring along new QoS aspects which
are not yet covered in [i.1], e.g.:
• CSFB, a procedure where the UE operating in LTE mode issues a special service request and the network
signals the device to move (fall back) to 2G/3G to accept incoming calls or to place outgoing calls;
• VoLTE, Voice over IP in LTE networks using a dedicated packet bearer and SIP signalling. It is based on the
IP Multimedia Subsystem (IMS) network with specific profiles for control and media planes. This approach
results in the voice service being delivered as data flow within the LTE data bearer.
The two scenarios mentioned above, very frequently encountered in European networks and worldwide, present specific
QoS issues that need to be addressed in detail.
Alternative approaches exist to carry voice calls in LTE networks such as SVLTE (Simultaneous Voice and LTE Data)
and VoLGA (Voice Over LTE via Generic Access). However, these are not addressed in the present document as they
have only limited industrial support at the time of publication of the present document.

ETSI

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6 ETSI TR 103 219 V1.1.1 (2015-04)
1 Scope
The aim of the present document is to identify and describe important aspects, related QoS parameters, their trigger
points and calculation methods in the context of voice communication taking place in an LTE environment.
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI TS 102 250-2 (V2.2.1): "Speech and multimedia Transmission Quality (STQ); QoS aspects
for popular services in mobile networks; Part 2: Definition of Quality of Service parameters and
their computation".
[i.2] ETSI TS 123 272 (V11.6.0): "Digital cellular telecommunications system (Phase 2+);Universal
Mobile Telecommunications System (UMTS); LTE; Circuit Switched (CS) fallback in Evolved
Packet System (EPS); Stage 2 (3GPP TS 23.272 version 11.6.0 Release 11)".
[i.3] ETSI TS 123 216 (V8.7.0): "Digital cellular telecommunications system (Phase 2+); Universal
Mobile Telecommunications System (UMTS); LTE; Single Radio Voice Call Continuity
(SRVCC); Stage 2 (3GPP TS 23.216 version 8.7.0 Release 8)".
[i.4] ETSI TS 123 237 (V10.7.0): "Digital cellular telecommunications system (Phase 2+); Universal
Mobile Telecommunications System (UMTS); LTE; IP Multimedia Subsystem (IMS) Service
Continuity; Stage 2 (3GPP TS 23.237 version 10.7.0 Release 10)".
[i.5] ETSI TS 123 216 (V11.11.0): "Digital cellular telecommunications system (Phase 2+); Universal
Mobile Telecommunications System (UMTS); LTE; Single Radio Voice Call Continuity
(SRVCC); Stage 2 (3GPP TS 23.216 version 11.11.0 Release 11)".
[i.6] ETSI TS 124 228 (V5.14.0): "Digital cellular telecommunications system (Phase 2+); Universal
Mobile Telecommunications System (UMTS); Signalling flows for the IP multimedia call control
based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3
(3GPP TS 24.228 version 5.14.0 Release 5)".
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7 ETSI TR 103 219 V1.1.1 (2015-04)
3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
2G 2nd Generation (mobile networks)
3G 3rd Generation (mobile networks)
3GPP 3rd Generation Partnership Project
4G 4th Generation (mobile networks)
CC Call Control
CM Connection Management
CS Circuit Switched
CSFB Circuit Switched Fall-Back
DL DownLink
DTM Dual Transfer Mode
EMM EPS Mobility Management
eNodeB Evolved Node B
EPS Evolved Packet System
E-UTRAN evolved UMTS Terrestrial Radio Access Network
GERAN GSM EDGE Radio Access Network
GSM Global System for Mobile communications
HO HandOver
IMS IP Multimedia Subsystem
IP Internet Protocol
IP-CAN IP Connectivity Access Network
IRAT Inter-Radio Access Technology
LTE Long-Term Evolution
MME Mobility Management Entity
NAS Non-Access Stratum
P-CSCF Proxy-Call Session Control Function
PS Packet Switched
QoS Quality of Service
RRC Radio Resource Control
S-CSCF Serving-Call Server Control Function
SIB System Information Block
SIP Session Initiation Protocol
SRVCC Single Radio Voice Call Continuity
STQ Speech and multimedia Transmission Quality
SVLTE Simultaneous Voice and LTE Data
UE User Equipment
UL UpLink
UMTS Universal Mobile Telecommunications System
UTRAN UMTS Terrestrial Radio Access Network
VoLGA Voice over LTE Generic Access
VoLTE Voice over LTE
4 Circuit-Switched Fall Back
4.1 General overview of CSFB
Initially, operators are introducing LTE for packed data services only. For stationary fixed line substitution scenarios
this was possible without special regards to existing circuit switched voice services. As LTE is now available on more
and more Smartphones and VoLTE is only starting to be commercially deployed, many operators have integrated the
circuit-switched fall back option to offer voice services to LTE-enabled handsets.
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8 ETSI TR 103 219 V1.1.1 (2015-04)
Therefore, a CS-capable Device registered to LTE needs to fall back to UMTS or even GSM before originating or
terminating a voice call. This can have influence on the perceived service quality in terms of:
• longer service access time for the voice service;
• higher risk of failing service access, in particular for mobile-terminated calls;
• interruption of the data service during the CSFB and continuation in slower UMTS network (or interruption of
the data service for the whole duration of the voice call in case of CSFB to GSM, if DTM is not available in
the network).

Figure 1: Mobile Originating call in Active Mode - PS HO supported
(figure taken from ETSI TS 123 272 [i.2])
4.2 Amendments to existing QoS parameters
4.2.1 CSFB Call Setup Failure Ratio [%]
4.2.1.1 Preconditions
For a valid calculation the following preconditions need to be met:
• LTE coverage should be present.
• The UE should be registered to the LTE network.
• CSFB feature should be enabled in the network and supported by the UE.
4.2.1.2 Abstract definition
This parameter is the probability that the CSFB terminal cannot setup a call.
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9 ETSI TR 103 219 V1.1.1 (2015-04)
4.2.1.3 Abstract equation
unsuccessful CSFB Call setup attempt
CSFB Call Setup Failure Ratio [%] = × 100
all CSFB Call setup attempt

4.2.1.4 Trigger points

Trigger point from user's point
Event from abstract equation Technical description/protocol part
of view
CSFB Call Setup attempt Start: Start:
User initiates call by pushing the "RRC Connection Request" with cause
call button. "mo_Data", if present.

Otherwise: "EMM Extended Service request
(CS fallback indicator)" message is sent by
calling party.
Successful CSFB Call Setup Stop: Stop:
attempt Alerting tone heard by calling party The "ALERTING" message is received by
and called party rings. calling party.
Unsuccessful CSFB Call Setup Stop: Stop:
attempt Calling party receives a notification Successful end trigger not reached within a pre-
that the call set-up is cancelled or determined time.
does not receive any notification at
all within a pre-determined time.

4.2.2 CSFB Call Setup Time [s]
4.2.2.1 Preconditions
For a valid calculation the following preconditions need to be met:
• LTE coverage should be present.
• The UE should be registered to the LTE network.
• CSFB feature should be enabled in the network and supported by the UE.
4.2.2.2 Abstract definition
This parameter is the time period between initiation and establishment of a CSFB call.
4.2.2.3 Abstract equation
CSFB Call Setup Time [s] =()t − t [s]
calling party receives Alerting tone user press call button

ETSI

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10 ETSI TR 103 219 V1.1.1 (2015-04)
4.2.2.4 Trigger points
Trigger point from user's point
Event from abstract equation Technical description/protocol part
of view
Start: Start:
t
user press call button
User initiates call by pushing the "RRC Connection Request" with cause
Time of user presses call button
call button. "mo_Data", if present.

Otherwise: "EMM Extended Service request
(CS fallback indicator)" message is sent by
calling party.
Stop: Stop:
t
A-party receives Alerting tone
Alerting tone heard by calling party The "ALERTING" message is received by
Time of calling party receives
and called party rings. calling party.
Alerting tone
NOTE: In case of networks employing "early-alerting" features the "CONNECT" message should replace the
"ALERTING" one, under the assumption that called party measurement system picks up the call after a
constant time interval after ringing and that the latter is subtracted by the gross call setup time.

For other CSFB call parameters such as CSFB Call Speech Quality on Call Basis and CSFB Call Speech Quality on
Sample Basis, which are the same as in regular telephony case, please refer to [i.1], clause 6.6.
4.3 Proposed new QoS parameters in the context of CSFB
4.3.1 Overview
Service access
...