TTCN-3 Based Automation Framework for LTE UE Protocol Stack

Report
TTCN-3 Based Automation Framework
for
LTE UE Protocol Stack Testing
Theofanis Vassiliou-Gioles
Testing Technologies
Ranganath Mahapatra
Larsen & Toubro Infotech
1
LTE Network Architecture
GERAN
SGSN
HSS
UTRAN
S3
S6a
S7
MME
LTE-Uu
UE
LTE-Uu
Operator IP
Services
PCRF
S10
eNB
S4
S11
Serving GW
S1u
S2a
X2
S5
Internet
PDN GW
S2c
SGi
S2b
ePDG
Trusted non 3GPP IP
Access
Trusted/Untrusted non3GPP/3GPP IP Access
Wn*
Untrusted
non 3GPP IP Access
UE
2
Network Simulator
Need for Simulated Environment
• Before porting a UE protocol stack to a Modem, a simulated environment is required for
test and verification
• Network simulator is implemented on a host environment consisting of an automation
framework, test scripts and the UE side interface.
Emulating Network Element Functionality
• Test environment emulates the functionality of the network elements.
• It interacts with the UE protocol stack through a common interface in a pre-determined
manner as per the test cases.
Manager, Logger, Debugger
• The frame work consists of a test manager, mechanism to capture logs, data analysis
and debugging capability in text and graphical mode.
• It provides scope for integration of external codec and plug ins.
3
Protocol Stack Functionality
NAS
NAS
Relay
RRC
RRC
PDCP
PDCP
SCTP
SCTP
RLC
RLC
IP
IP
MAC
MAC
L2
MAC
L1
L1
L1
L1
UE
LTE-Uu
S1-AP
eNobeB
S1-AP
S1-MME
MME

UE protocol stack communicates with multiple elements in the network side though eNodeB.

UE control plane protocol layers are mapped to eNodeB and MME.

Except for the NAS layer messages, the other layers of UE interact directly with eNodeB
protocol stack.
4
Testing Architecture
Test Management
Control & Logging
Automation Framework
TCI
UE Protocol Stack
ETSI Test Scripts in TTCN-3
TRI
RRC
DRB Codec
SRB Codec ASN.1
Codec Layer
PDCP
RLC
PDCP
RLC
MAC
L2 Layer Stubs
MAC
MAC-Phy
MAC-Phy
System Adaption Layer
UDP / IP
5
Components
Codec
• Encodes and decodes the RRC messages which are defined in EUTRA_RRC_ASN1_Definitions.
• The default technique for encoding and decoding is as per RRC standard 36.331 is “PER-BASICUNALIGNED: 2002”.
L2 Layer Stubs
• PDCP, RLC and MAC header encapsulation and de-capsulation of messages and PDUs are some of
the functionalities of this module.
• Other basic functionalities/procedures of PDCP, RLC and MAC, ex - RACH procedure, broadcast
etc are also implemented.
System Adaptation Layer
• defines the communication protocol between eNodeB and UE protocol stack.
• The function of MAC-Phy interface is for the synchronization of eNodeB with UE protocol stack on
UDP/IP.
Wireshark Dissection Implementation
• MAC-Phy layer encapsulates its header into the messages.
• Wireshark doesn’t support these headers, so required dissectors are implemented in wire-shark
to dissect and understand the LTE messages sent via PHYSAP interface.
ETSI Test Script
• Consists of test cases, templates, records, functions, interfaces and TTCN3 ports (TCI & TRI
Ports).
• Additional test cases were also developed to improve the coverage.
6
Incremental Development & Testing
7
Test Execution
 Test case drives the specified procedures for
validation of the stack.
 The Test Manager of IDE provides a GUI interface to
run the test cases individually or in batches.
 The frame work provides log capturing and debugging
mechanism both in text and graphical representation
8
Our Value Adds on ETSI’s Solution

ETSI’s Solution
–
ETSI Test suite provides TTCN-3 scripts for protocol conformance testing.
–
It provides parallel test components and ports for seamless mapping of protocol layers for
network side entities.

Our Value Adds
–
In order to optimize the development cycle, we have utilized ETSI test suites,
commercially available IDE and external plug ins.
–
Adaptation layers were developed
–
A pseudo MAC-Phy interface layer was implemented.
9
Challenges
Codec’s and Adaptation Layers : Requires good understanding of protocol stack layers
and specification
Debugging and classification of issues: Differencing between test framework and UE
issues
Concurrent Development : Development of Test Framework (IDE), ETSI test cases and
UE Protocol stack
Identification of suitable commercial IDE
10
Thank You
Experts in Test
Automation
Our Business Knowledge,
Your Winning Edge.

similar documents