LTE pre-SI Test Suite
Implementation in TTCN3: A case study
Pramod Shrivastava
Intel Mobile Communication
Nitin Bodas
Larsen & Toubro Infotech
Ranganath Mahapatra
Larsen & Toubro Infotech
1
Introduction
LTE pre-System Integration (pre-SI) test suite for testing UE modem in a simulated
environment.
Specifically designed to address IOT, field testing, inter-RAT scenarios and testing of
complex functional areas.
Implemented on a multi-mode LTE protocol stack running on a host system and
interacting with an automation framework through message queues.
The main objective of this suite was to advance the testing phase, typically carried out
at a later stage and thereby improve the overall testing process.
The test cases were developed in TTCN3.
2
UE Modem Development & Validation Phases
Protocol Layers
Physical and RF Layer
Advance Features
OS Porting & Peripherals
Pre-SI
Conformance Testing
Certification Support
Field Testing
Requirement Testing
Performance &
Stress Testing
IOT
SI
Operator Acceptance
Testing
Post-SI
 Pre-SI phase: Protocol layers such as Physical Layer, L2 and L3 consisting of MAC, RRC, RLC, NAS & PDCP
layers are developed independently
 SI Phase: Protocol layers (L2 &3) are integrated with physical layer, RF and other components or
modules and ported to UE modem
 Post-SI Phase: the UE modem undergoes development and validation with focus on customer acceptance,
certification testing etc.
3
Incremental Development & Testing
Test Case Execution
Test Case
Development/Enhancement
Protocol Stack
Development/Enhancement




 Release 8
 Release 9
 Release 10
Phase-1
Phase-2
Phase-3
………
Host Environment
Development




Phase-1
Phase-2
Phase-3
………
4
3GPP Releases & Features covered in the Test Suite
LTE/EPC Rel. 8

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

LTE FDD & TDD Interfaces
LTE FEDD & TDD Layer 1,2,3
delimitations
Security support
Mobility Features & IRAT
EPC Definition and support
EPC charging
Advanced Antenna,: MIMO, FSS
CS Fall Back
SRVCC
SON Features
Home eNB
IMS Support
LTE/EPC Rel. 9



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
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Positioning Support
LTE in 800 MHz
NW based Positioning
IMS Emergency
Public Warning System
Home eNB
eMBMS support in LTE
Enhanced DL Transmission
Vocoder rate adaptation
SON Features
LTE/EPC Rel. 10


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Bandwidth
aggregation
Relays and Repeaters
MIMO Enhancements
Multisite Cooperative
Transmission
 Incremental approach to develop the stack, network emulator and test suite.
 Synced up with 3GPP releases with respect to feature enhancements and addition of new features.
 Test Cases categorized into complex functional, IOT, security, inter-RAT, field testing and other
functional areas.
5
Filtering of Test Cases
SI Test Cases
 Complex Functional Test Cases
 Field Test Cases
 IOT Test Cases
 GCF Test Cases
Influenced Test Cases
 Pre-SI Phase 1
 Pre-SI Phase 2
 Pre-SI Phase 3
Non-Influenced Test Cases
6
Test Environment
Network Side Emulator
2G/3G/4G UE
System
Adaptation Layer
/ NAS
Layer 3
Pre-SI Test Suite
in TTCN-3
System
Adaptation Layer
System
Adaptation Layer
2G/3G/
L2 Layer
4G LTE
(PDCP/RLC/MAC)
L1
MAC Adaptation
Layer
AT/MMI
Commands
Layer 2
MAC Adaptation
Layer
MSG Q or UDP/IP
 The test cases are executed using host based tri-mode automation framework.
 It supports validation of both LTE and legacy technologies.
 The framework and UE protocol stack interact with each other in message queues and also
preserves LTE frame timing.
7
Sample Scenario#1
LTE
[Packet Call]
CS-FB call
UMTS
Add a bearer
End CS-FB
call
back to LTE with
both bearers.
MT Voice Call
Voice Call End
Web Browsing
CS-fall back
FTP Download
8
Sample Scenario#2
UE circulates around cells of different RATs
9
Addressing Challenges
 Test scenario identification is one of the key challenges in the development of the
pre-SI Test suite due to limitations and evolution of protocol stack or host
environment.
 These challenges are addressed ensuring the following aspects:
 Extensive knowledge of standard and release enhancements in multi RAT
context
 Extensive knowledge in SI and post-SI test areas
 Test coverage to replicate field or real life scenarios including negative and
concurrent scenarios etc
 Test cases were converted in to message flows followed by scripting which requires
excellent understanding of the interaction between UE modem and network.
10
Conclusion
Pre-SI test suite was developed with test scenarios typically executed in SI and post-SI
phases.
The objective of this suite is to reduce multimode LTE UE development time.
The test suite is designed such that it can also be used in SI and post-SI phase on
commercial network simulator.
The suite is continually enhanced to keep in sync with the evolution of 3GPP standard.
11
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