ETSI TS 138 509 V15.5.0 (2019-10)

5G; 5GS; Special conformance testing functions for User Equipment (UE) (3GPP TS 38.509 version 15.5.0 Release 15)

RTS/TSGR-0538509vf50

General Information

• Status: Published
• Publication Date: 16-Oct-2019
• Technical Committee: 3GPP RAN 5 - Mobile Terminal Conformance Testing (formely T1)
• Current Stage: 12 - Completion
• Completion Date: 17-Oct-2019

Standards Content (Sample)

TECHNICAL SPECIFICATION
5G;
5GS;
Special conformance testing functions
for User Equipment (UE)
(3GPP TS 38.509 version 15.5.0 Release 15)

3GPP TS 38.509 version 15.5.0 Release 15 1 ETSI TS 138 509 V15.5.0 (2019-10)

Reference
RTS/TSGR-0538509vf50
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3GPP TS 38.509 version 15.5.0 Release 15 2 ETSI TS 138 509 V15.5.0 (2019-10)
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Legal Notice
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3GPP TS 38.509 version 15.5.0 Release 15 3 ETSI TS 138 509 V15.5.0 (2019-10)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 5
1 Scope . 6
2 References . 6
3 Definitions, symbols and abbreviations . 7
3.1 Definitions . 7
3.2 Symbols . 8
3.3 Abbreviations . 8
4 UE special conformance test functions overview . 8
4.1 Requirements for UE support of test functions . 8
4.2 UE special conformance test functions concept . 8
5 UE special conformance test functions operation . 9
5.1 General . 9
5.2 Activation and deactivation of 5GS test mode bearers (UE test mode procedures) . 10
5.2.1 General . 10
5.2.2 Activate UE test mode . 10
5.2.3 Deactivate UE test mode . 10
5.3 Test loop functions . 10
5.3.1 General . 10
5.3.2 Close UE test loop . 11
5.3.3 Open UE test loop . 11
5.3.4 UE functionality when test loop is closed . 11
5.3.4.1 UE test loop mode A operation . 11
5.3.4.2 UE test loop mode B operation . 14
5.3.4.2.1 General . 14
5.3.4.2.2 UE test loop mode B operation for EN-DC and NGEN-DC . 15
5.3.4.2.3 UE test loop mode B operation for Standalone NR . 17
5.4 UE Beamlock test Function (UBF) . 19
5.4.1 General . 19
5.4.2 Activate Beamlock procedure . 19
5.4.2.1 Initiation . 19
5.4.2.2 Reception of ACTIVATE BEAMLOCK message by UE . 19
5.4.3 Deactivate Beamlock procedure . 20
5.4.3.1 Initiation . 20
5.4.3.2 Reception of DEACTIVATE BEAMLOCK message by UE . 20
5.4.3.3 Release of antenna beamlock by UE . 20
5.5 UE SS-RSRPB per receiver branch reporting . 20
5.5.1 General . 20
5.5.2 Initiation . 21
5.5.3 Reception of SS-RSRPB REPORT REQUEST message by UE . 21
5.6 UE Positioning test mode procedures . 22
5.6.1 Reset UE Positioning Stored Information . 22
5.6.1.1 General . 22
5.6.1.2 Initiation . 22
5.6.1.3 Reception of RESET UE POSITIONING STORED INFORMATION message by UE . 22
5.6.2 Update UE Location Information . 22
5.6.3 UTC time reset . 22
5.7 NSSAI delete test function . 22
5.7.1 General . 22
6 Test Mode Control message definitions . 24
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6.1 General . 24
6.2 Test mode messages . 24
6.2.1 ACTIVATE TEST MODE . 24
6.2.2 ACTIVATE TEST MODE COMPLETE . 25
6.2.3 DEACTIVATE TEST MODE . 25
6.2.4 DEACTIVATE TEST MODE COMPLETE . 25
6.3 Test loop messages . 25
6.3.1 CLOSE UE TEST LOOP . 25
6.3.2 CLOSE UE TEST LOOP COMPLETE. 25
6.3.3 OPEN UE TEST LOOP . 25
6.3.4 OPEN UE TEST LOOP COMPLETE . 25
6.3.5 Void . 26
6.3.6 Void . 26
6.4 Beamlock messages . 26
6.4.1 ACTIVATE BEAMLOCK . 26
6.4.2 ACTIVATE BEAMLOCK COMPLETE . 26
6.4.3 DEACTIVATE BEAMLOCK . 27
6.4.4 DEACTIVATE BEAMLOCK COMPLETE . 27
6.5 UE SS-RSRP per receiver branch reporting messages . 27
6.5.1 SS-RSRPB REPORT REQUEST . 27
6.5.2 SS-RSRPB REPORT RESPONSE . 28
6.6 UE Positioning messages . 28
6.6.1 RESET UE POSITIONING STORED INFORMATION . 28
6.6.2 UPDATE UE LOCATION INFORMATION . 28
6.7 NSSAI delete messages . 29
6.7.1 NSSAI DELETE REQUEST . 29
6.7.1 NSSAI DELETE RESPONSE . 30
7 Variables, constants and timers . 30
7.1 State variables . 30
7.2 Constants . 30
7.3 Timers . 31
7.4 Configurable parameters . 31
8 Electrical Man Machine Interface (EMMI) . 31
Annex A (informative): Change history . 32
History . 33

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3GPP TS 38.509 version 15.5.0 Release 15 5 ETSI TS 138 509 V15.5.0 (2019-10)
Foreword
This Technical Specification has been produced by the 3rd 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.
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1 Scope
The present document defines for User Equipment (UE) those special functions and their activation/deactivation
methods that are required in the UE for conformance testing purposes when the UE is connected to the 5G System
(5GS) via its radio interface(s).
The document also describes the operation of these special functions when the 5GS capable UEs are connected via a
non-5GS system e.g. E-UTRA FDD or TDD system.
Depending on the 5GS system's architecture some relevant for the UE for conformance testing special functions may be
defined in TS 36.509 [6].
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 unless the context in which the reference is made suggests a different Release is
relevant (information on the applicable release in a particular context can be found in e.g. test case title,
description or applicability, message description or content).
[1] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications".
[2] 3GPP TS 38.508-1: "5GS; User Equipment (UE) conformance specification; Part 1: Common test
environment ".
[3] 3GPP TS 38.523-1: "5GS; User Equipment (UE) conformance specification; Part 1: Protocol ".
[4] 3GPP TS 38.523-3: "5GS; User Equipment (UE) conformance specification; Part 3: Protocol Test
Suites "
[5] 3GPP TS 38.522: "NR; User Equipment (UE) conformance specification; Applicability of RF and
RRM test cases".
[6] 3GPP TS 36.509: "Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Packet
Core (EPC); Special conformance testing functions for User Equipment (UE)".
[7] 3GPP TS 24.007: "Mobile radio interface signalling layer 3; General Aspects".
[8] 3GPP TS 34.109: "Terminal logical test interface; Special conformance testing functions".
[9] 3GPP TS 44.014: "Individual equipment type requirements and interworking; Special
conformance testing functions".
[10] 3GPP TS 36.331: "Evolved Universal Terrestrial Radio Access (EUTRA) Radio Resource Control
(RRC) Protocol Specification".
[11] 3GPP TS 38.331: "NR Radio Resource Control (RRC) protocol specification".
[12] 3GPP TS 38.521-1: "NR; User Equipment (UE) conformance specification; Radio transmission
and reception; Part 1: Range 1 Standalone".
[13] 3GPP TS 38.521-2: "NR; User Equipment (UE) conformance specification; Radio transmission
and reception; Part 2: Range 2 Standalone".
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[14] 3GPP TS 38.521-3: "NR; User Equipment (UE) conformance specification; Radio transmission
and reception; Part 3: Range 1 and Range 2 Interworking operation with other radios".
[15] 3GPP TS 38.521-4: "NR; User Equipment conformance specification; Radio transmission and
reception; Part 4: Performance".
[16] 3GPP TS 38.533: NR; "User Equipment (UE) conformance specification; Radio resource
management".
[17] 3GPP TS 24.301: "Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage
3".
[18] 3GPP TS 36.323: "Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data
Convergence Protocol (PDCP) specification".
[19] 3GPP TS 38.323: "NR; Packet Data Convergence Protocol (PDCP) specification".
[20] 3GPP TS 38.306: "NR; User Equipment (UE) radio access capabilities".
[21] 3GPP TS 24.501: "Non-Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3".
[22] 3GPP TS 38.215: "NR; Physical Layer Measurements".

3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in 3GPP TR 21.905 [1] and the following
apply. A term defined in the present document takes precedence over the definition of the same term, if any, in 3GPP
TR 21.905 [1].
Frequency Range 2 (FR2): The frequency ranges in which NR can operate being in the range of 24250 MHz - 52600
MHz.
Logical Test Interface: interface which provides the logical service to interwork and to communicate between UE and
System Simulator during the test of a UE
SS (System Simulator): test system (or equipment) that drives the test process with UE, like 5G System simulator
TMC (Test Mode Control): UE protocol entity used by the SS to control the UE specific testing functions
NOTE: In other Special conformance testing functions for User Equipment (UE) 3GPP specifications e.g. 36.509
[6], the term Test Control (TC) is used for describing the same UE entity. The different names do not
preclude the implementation of a single entity to handle all the functionality in a UE supporting different
3GPP technologies.
UE (User Equipment): user equipment as defined in [1] that is under test
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3.2 Symbols
No specific symbols apply for the purposes of the present document.
3.3 Abbreviations
For the purposes of the present document, the abbreviations given in 3GPP TR 21.905 [1] and the following apply. An
abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in
3GPP TR 21.905 [1].
EMMI Electrical Man Machine Interface
FFS For further Study
FR2 Frequency Range 2
LB Loop Back
MTC Main Test Component
NSSAI Network Slice Selection Assistance Information
SS System Simulator
TMC Test Mode Control
4 UE special conformance test functions overview
4.1 Requirements for UE support of test functions
The UE special conformance test functions are required for the support of 5GS conformance testing. They form a part
of the core requirements and thus have a direct impact on the design of the UE. The use of the word "mandatory" in the
present specification shall be understood as a particular requirement being mandatory for performing UE conformance
testing.
NOTE: While the importance of conformance testing should not be underestimated, and hence is highly
recommended, the implementation of facilitation of it is left to the Device implementation.
4.2 UE special conformance test functions concept
The present specification defines the UE special conformance test functions including any relevant procedure and the
Test Mode Control (TMC) message contents used for information exchange.
The conformance test methods applied in RF/RRM Conformance Test Specification TS 38.521-1 [12], TS 38.521-2
[13], TS 38.521-3 [14], TS 38.521-4 [15] and TS 38.533 [16], and, the conformance test models used in Protocol
Conformance Test Specifications TS 38.523-1 [3] and TS 38.523-3 [4], as well as, common test environment definition
and Generic procedures specified in TS 38.508-1 [2] utilise the UE special conformance test functions. Default TMC
messages and information element contents utilised in all before mentioned test specifications are specified in TS
38.508-1 [2].
The UE special conformance test functions vary depending on the conformance testing functionality they are designed
to support. The following broader groups of UE special conformance test functions can be identified:
- Test Loop Functions: Functions which require a loop to be established between the UE and the System
Simulator (SS) to allow e.g. DL data packets sent by the SS to be looped back UL by the UE
- General Test Functions: Commands send by the SS e.g. to trigger a certain UE behaviour which may be a
behaviour determined by 3GPP core spec requirements or such needed to facilitate conformance testing and not
being part of any 3GPP core spec requirements, or, to provide to the UE information needed for the conformance
testing.
NOTE 1: An example for behaviour needed to facilitate conformance testing and not representing behaviour
determined by 3GPP core spec requirements is counting and reporting the number of received data
packets thereby providing means to the SS to verify 3GPP core spec requirements.
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The utilisation of any UE special conformance test functions shall be considered as putting the UE in a test mode. The
duration of the test mode depends on the UE special conformance test function and in most of the cases will be
delimited by an activation and a deactivation command. However, in the case of general test functions used e.g. only to
provide information relevant for the conformance testing the test mode can be considered as entered as soon as the
information is received and exited as soon as the information has been acted upon.
As a common rule the UE special conformance test functions provide access to isolated functions of the UE via the
radio interface without introducing new physical interfaces just for the reason of conformance testing. However, in
certain cases the usage of AT Commands may be required which will require an external interface e.g. EMMI.
NOTE 2: It should be emphasised that the UE test functions only describe the functional behaviour of the UE with
respect to its external interfaces; physical implementation of the UE test function is completely left open
to the manufacturer.
Depending on the conformance testing functionality they are designed to support, the UE special conformance test
functions may comprise:
- A single DL message (e.g. a test function intended to provide to the UE information needed for the conformance
testing)
- A Request/Acknowledgement type of 2 messages exchange, an DL message followed by a UL message, (e.g. a
test function intended to request the UE to execute an action which requires acknowledgment that request was
received and acted upon)
Furthermore, depending on the conformance test scenarios
- An UE special conformance test function can be used in isolation.
NOTE 3: An example for this is the provision to the UE of location information which can then be used by the UE
throughout its "normal" i.e. not test mode functions dependant behaviour.
- Two, or more, UE special conformance test functions may need to be executed in a particular sequence before
the target UE behaviour can be assumed.
NOTE 4: An example for this are the Activate UE test mode and Close UE test loop functions. The former needs to
be executed first, at a particular moment of time, in order a specific type of test bearer terminated in a
particular UE protocol layer to be established. Followed by the latter, executed at different point of time,
which will instruct the UE to start looping back the received packets.
- Two, or more, UE special conformance test functions may be executed simultaneously with no particular relation
one to another allowing for different test mode functionality to take place at the same time.
NOTE 5: An example for this are the UE Beamlock test function and the test functions needed for test loop mode
operation (see NOTE 4). The former may need to be active throughout the entire tests with the latter
being active in parts of the test as appropriate. Both being active independently.
For the specification of UE special conformance test functions the present specification may refer to other
specifications. In the case when text on the same matter exists in the present specification and in the referred
specification, the text in the present specification takes precedence.
5 UE special conformance test functions operation
5.1 General
For consistency with legacy terminology, the present specification uses the terms 'Activate UE test mode' and
'Deactivate UE test mode' for denoting the activation and the deactivation of 5GS test mode bearers procedures
respectively. Consequently, 'Activate UE test mode' should not be understood as setting the UE in test mode in general
rather, as setting the UE in a mode (i.e. establishing a special type of test bearers) which other special UE conformance
testing functions require for proper operation. As this has been mentioned elsewhere in the present specification, not all
special UE conformance testing functions require such a setting.
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3GPP TS 38.509 version 15.5.0 Release 15 10 ETSI TS 138 509 V15.5.0 (2019-10)
Similarly, the present specification may use the term 'UE test loop mode X operation", where X is a chose letter, for
denoting operation which does not represent true looping back of data being received rather, it represents what can be
called as a "pseudo loop" i.e. providing back information about the received data e.g. the number of the received
packets.
5.2 Activation and deactivation of 5GS test mode bearers (UE
test mode procedures)
5.2.1 General
The SS performs, where applicable, activation and deactivation of the conformance test functions in the UE by sending
Security Protected NAS Layer 3 messages.
The UE test mode procedures are intended for setting the UE into a test mode where the SS can set up test bearers
terminated at a particular point in the 5GS protocol stack as specified in the functional block diagram of each UE test
loop mode of operation. The following test bearers are defined in the present specification:
- data radio bearers (UE test loop mode A),
- EPS bearers or 5GS QoS flows (UE test loop mode B).
5.2.2 Activate UE test mode
Same as TS 36.509 [6], subclause 5.3.2 with the following exceptions:
- where E-UTRA is mentioned the same applies for NR;
the NB-IoT mode is out of the scope of the present specification;
where different UE test loop modes are mentioned only those applicable to 5GS should be taken into account
(see subclause 5.3.4 for the applicable 5GS UE test loop modes).
5.2.3 Deactivate UE test mode
Same as TS 36.509 [6], subclause 5.3.3 with the following exceptions
- where E-UTRA is mentioned the same applies for NR;
- the NB-IoT mode is out of the scope of the present specification;
- where different UE test loop modes are mentioned only those applicable to 5GS should be taken into account
(see subclause 5.3.4 for the applicable 5GS UE test loop modes).
Apart from sending the appropriate deactivation command to the UE the functions shall be deactivated by:
switching off the UE; or
by removing the USIM.
5.3 Test loop functions
5.3.1 General
Before a loop functionality can be exercised, the test loop needs to be closed; this is to be understood as the UE being
instructed to start looping back received data packets. When looping back received data packets is not any longer
required the loop should be re-opened; opening of a loop does not change the type of bearer being established by the UE
test mode activation function (subclause 5.2.2).
To limit the number of special test functions, the concept of closing and opening a loop is also used as instruction to the
UE to initiate/terminate other actions. An example of this is counting the received packets and reporting the number of
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received packets back to the SS; in the context of this utilisation closing a loop is to be understood as the UE being
instructed to start counting the packets, whereas opening a loop should be understood as stop counting the packets.
Other utilisation of the closing/opening a "test loop" test functionality can be specified if appropriate.
The UE test loop functions for 5GS are intended for:
- NR receiver and transmitter testing to disable application data transfer in downlink and uplink during SS UE
measurements.
- NR layer 2 (MAC, RLC, PDCP, SDAP) and data radio bearer testing to generate data transfer in downlink and
uplink.
- 5GC and NR layer 3 testing to verify data transfer continuation over RRC and 5GC procedures.
- 5GC NAS user-plane testing to verify uplink QoS flow descriptions handling.
5.3.2 Close UE test loop
Same as TS 36.509 [6], subclause 5.4.2 with the following exceptions:
- where E-UTRA is mentioned the same applies for NR;
- the NB-IoT mode is out of the scope of the present specification
- where different UE test loop modes are mentioned only those applicable to 5GS should be taken into account
(see subclause 5.3.4 for the applicable 5GS UE test loop modes).
- where EPS bearers are mentioned the same applies for 5GS QoS flows; and
- UE supported minimum buffer size for MR-DC and NR shall match the required total layer 2 buffer size as
specified in TS 38.306 [20], clause 4.1.4.
5.3.3 Open UE test loop
Same as TS 36.509 [6], subclause 5.4.5 with the exceptions:
- where E-UTRA is mentioned the same applies for NR;
- the NB-IoT mode is out of the scope of the present specification;
- where different UE test loop modes are mentioned only those applicable to 5GS should be taken into account
(see subclause 5.3.4 for the applicable 5GS UE test loop modes).
5.3.4 UE functionality when test loop is closed
5.3.4.1 UE test loop mode A operation
Editor’s note: Functional block diagrams for UE test loop mode A for NE-DC need to be added.
UE test loop mode A provides loopback of PDCP SDUs for bi-directional data radio bearers while UE is operating in
NR. The downlink PDCP SDUs received by the UE on each bi-directional data radio bearer are returned on the same
radio bearer regardless of the PDCP SDU contents and of the QoS flow descriptions of the associated QoS Flow as
specified in TS 24.501 [21].
Figures 5.3.4.1-1 and 5.3.4.1-2 show functional block diagrams of UE test loop function for the TMC entity and UE test
loop mode A for the case when EN-DC or NGEN-DC with a MCG bearer and a SCG bearer is configured and for the
case EN-DC or NGEN-DC with a MCG and a split bearer is configured.
Figures 5.3.4.1-3 shows functional block diagrams of UE test loop function for the TMC entity and UE test loop mode
A for the case when standalone NR is configured.
NOTE 1: The number and the order of RB LB Entities in the functional block diagrams are provided for illustration
only. No specific order or numbering is precluded.
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Test Mode
UE Test Loop Function
Control
UE Test Loop Mode A
RB LB
RB LB RB LB
Entity#k
Entity#k+1 Entity#k+2
MCG DRB
MCG DRB SCG DRB
RRC
CNTRL SRB1/SRB2
ROHC ROHC
ROHC
Ciphering Ciphering Ciphering
E-UTRA/
NR PDCP
NR PDCP
AM/UM AM/UM AM/UM
E-UTRA RLC NR RLC
DTCH
DTCH
E-UTRA MAC NR MAC
NR PHY
E-UTRA PHY
Tx Rx
Tx Rx
Test System
Figure 5.3.4.1-1: Model for Test Mode Control and UE Test Loop Mode A on UE side when EN-DC or
NGEN-DC with MCG bearer and SCG bearer is configured

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Test Mode
UE Test Loop Function
Control
UE Test Loop Mode A
RB LB
RB LB
Entity#k
Entity#k+1
MCG DRB
Split DRB
RRC
CNTRL        SRB1/SRB2
ROHC
ROHC
Ciphering Ciphering
E-UTRA/NR
NR
PDCP
PDCP
AM/UM AM/UM AM/UM
E-UTRA RLC NR RLC
DTCH
DTCH
E-UTRA MAC NR MAC
NR PHY
E-UTRA PHY
Tx Rx
Tx Rx
Test System
Figure 5.3.4.1-2: Model for Test Mode Control and UE Test Loop Mode A on UE side when EN-DC or
NGEN-DC with MCG and split bearer configured

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Test Mode
UE Test Loop Function
Control
UE Test Loop Mode A
RB LB
RB LB
Entity#k
Entity#k+1
DRB#k
RRC DRB#k+1
CNTRL SRB1/SRB2
ROHC ROHC
Ciphering Ciphering
NR PDCP
AM/UM AM/UM
NR RLC
DTCH
NR MAC
NR PHY
Tx Rx
Test System
Figure 5.3.4.1-3: Model for Test Mode Control and UE Test Loop Mode A on UE side when standalone
NR is configured
UE test loop mode A is mandatory to all 5GS UEs.
Prior to closing the UE test loop mode A, thereby requesting the UE to start looping back the received data packets, at
least one 5GS test mode bi-directional data radio bearer shall have been established between SS and UE. This implies
that before the procedure for establishing the bi-directional data radio bearer takes place the SS needs to activate the UE
test mode as specified in subclause 5.2.2.
The 5GS UE test loop mode A operation is the same as the one described in TS 36.509 [6], subclause 5.4.3 with the
exception where E-UTRA is mentioned the same applies for NR, and, the understanding that the NB-IoT mode is out of
the scope of the present specification.
5.3.4.2 UE test loop mode B operation
Editor’s note: Functional block diagrams for UE test loop mode B for NE-DC need to be added.
5.3.4.2.1 General
UE test loop mode B is mandatory to all 5GS UEs supporting one or more PDU session establishments.
ETSI
3GPP TS 38.509 version 15.5.0 Release 15 15 ETSI TS 138 509 V15.5.0 (2019-10)
5.3.4.2.2 UE test loop mode B operation for EN-DC and NGEN-DC
UE test loop mode B provides loopback of PDCP SDUs for bi-directional EPS bearers while UE is operated in NR or
E-UTRA modes. When operating in NR or E-UTRA, the downlink PDCP SDUs or SNDCP PDUs received by the UE
on all bi-directional data radio bearers are returned by the UE on the data radio bearer associated with an QoS Flow
with a QoS flow descriptions matching the TCP/UDP/IP protocol information within the PDCP SDU or SNDCP SDU
as specified in TS 24.501 [21].
NOTE 1: When multiple PDN connections are established (or multiple Primary PDP Contexts are active), it is
assumed that different IP addresses are allocated to the UE by the SS on each PDN.
Figures 5.3.4.2.2-1 and 5.3.4.2.2-2 show functional block diagrams of UE test loop function for the TMC entity and UE
test loop mode B for the case when EN-DC or NGEN-DC with a MCG bearer and a SCG bearer is configured and for
the case EN-DC or NGEN-DC with a MCG and a split bearer is configured.
NOTE 2: The number and the order of RB LB Entities in the UE Test Loop Function in the functional block
diagrams are provided for illustration only. No specific order or numbering is precluded.
ETSI
3GPP TS 38.509 version 15.5.0 Release 15 16 ETSI TS 138 509 V15.5.0 (2019-10)

UE Test Loop Function
Test Mode
UE Test Loop Mode B
Control
In E-UTRA mode
LB
NAS
Entity
UL TFT
Mapping
SDF to EPS bearer
(UL TFT handling)
RRC
IP PDUs = PDCP SDUs
CNTRL
SRB1/SRB2
SCG DRB
MCG DRB
ROHC ROHC
Ciphering Ciphering NR
E-UTRA / NR
PDCP PDCP
AM/UM AM/UM
E-UTRA RLC
NR RLC
DTCH DTCH
E-UTRA MAC NR MAC
E-UTRA PHY NR PHY
Tx Rx
Tx Rx
Test System
Figure 5.3.4.2.2-1: Model for Test Mode Control and UE Test Loop Mode B on UE side when EN-DC or
NGEN-DC with MCG bearer and SCG bearer is configured

ETSI
3GPP TS 38.509 version 15.5.0 Release 15 17 ETSI TS 138 509 V15.5.0 (2019-10)

UE Test Loop Function
Test Mode
UE Test Loop Mode B
Control
In E-UTRA mode
NAS
LB
Entity
UL TFT
Mapping
SDF to EPS bearer
(UL TFT handling)
RRC
IP PDUs = PDCP SDUs
CNTRL
SRB1/SRB2
Split DRB
MCG DRB
ROHC ROHC
Ciphering Ciphering
E-UTRA / NR
NR
PDCP
PDCP
AM/UM AM/UM
AM/UM
E-UTRA RLC NR RLC
DTCH
DTCH DTCH
E-UTRA MAC NR MAC
E-UTRA PHY NR PHY
Tx Rx
Tx Rx
Test System
Figure 5.3.4.2.2-2: Model for Test Mode Control and UE Test Loop Mode B on UE side when EN-DC or
NGEN-DC with MCG and split bearer configured

5.3.4.2.3 UE test loop mode B operation for Standalone NR
UE test loop mode B provides loopback of SDAP SDUs for bi-directional QoS Flows while UE is operated in
standalone NR mode. Prior to closing the UE test loop mode B, thereby requesting the UE to start looping back the
received data packets, at least one 5GS test mode bi-directional QoS Flow shall have been established between SS and
UE. This implies that before the procedure for establishing the bi-directional QoS Flows takes place the SS needs to
activate the UE test mode as specified in subclause 5.2.2
The downlink SDAP SDUs or IP PDU's received by the UE on all bi-directional QoS Flows are returned by the UE
without any modification of the IP header to the UL QoS flow descriptions handling SAP for transmission in uplink.
NOTE 1: When multiple PDU sessions are established, it is assumed that different IP addresses are allocated to the
UE by the SS on each PDU session.
ETSI
3GPP TS 38.509 version 15.5.0 Release 15 18 ETSI TS 138 509 V15.5.0 (2019-10)
Figure 5.3.4.2.3-1 shows functional block diagrams of UE te
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