Operator-provided voice services will gradually migrate from today’s circuit-switched (CS) voice networks to packet-switched IP networks, using Voice over LTE (VoLTE) as the foundation to provide telecom-grade telephony services. In fact, the capability of transporting Voice over IP (VoIP) services along with the provision of high-rate data throughputs, characterizes one of the critical drivers for the LTE development.
This thesis presents the first implications of introducing IMS-based VoLTE in Germany, Austria and Switzerland (DACH) from a mobile operator’s perspective. Further VoLTE performance aspects such as parameter optimization and HD voice are discussed, thus serving as a basis to then analyze the DACH mobile network test results for 2014 in terms of telephony and data performance. Overall results for a DACH VoLTE trial conducted in the third quarter 2014 complement the analysis.
Table of Contents
1 Introduction
2 Migrating to IMS-based VoLTE: Initial considerations
2.1 Benefits of IMS-based VoLTE
2.2 Providing voice over LTE
2.2.1 Circuit-switched Fallback (CSFB)
2.2.2 Voice over LTE (VoLTE)
2.3 VoLTE Logical Architecture
2.3.1 4G LTE network architecture
2.3.2 VoLTE Functional Node Description
2.4 Assessing the Voice Quality Performance
2.4.1 Leveraging the Operators’ Assets
2.4.2 Development of audio testing
2.4.3 PESQ/POLQA methodology
3 VoLTE Parameter Optimization
3.1 Robust Header Compression (RoHC)
3.2 Transmission Time Interval (TTI) Bundling
3.3 Discontinuous Reception (DRX)
3.4 Dedicated Bearers
3.5 Semi-Persistent Scheduling (SPS)
4 VoLTE Testing
4.1 Primary Implications
4.1.1 Voice Quality of VoLTE versus OTT Voice Services
4.1.2 Mobile Network Test: Testing Framework
4.2 Mobile Network Test 2014: Connect Magazine
4.2.1 Organizational aspects
4.2.2 Test methodology
4.2.3 Germany: Telephony Test Results
4.2.4 Germany: Data Test Results
4.2.5 Austria: Telephony Test Results
4.2.6 Austria: Data Test Results
4.2.7 Switzerland: Telephony Test Results
4.2.8 Switzerland: Data Test Results
4.2.9 Mobile Network Test: Overall Results DACH Region
4.2.10 Austria: VoLTE Friendly User Tests
4.3 Mobile Network Test 2014: CHIP Magazine
4.3.1 Test methodology
4.3.2 Germany: Telephony Test Results
4.3.3 Germany: Data Test Results
5 Conclusion
Objectives & Core Topics
This thesis examines the technical and strategic migration of mobile operators from traditional circuit-switched voice services to IP-based Voice over LTE (VoLTE). It evaluates implementation strategies, network parameter optimization, and performance benchmarking to ensure high-quality telephony in all-IP environments.
- Technical architecture and functional nodes of VoLTE and IMS.
- Performance optimization techniques (e.g., RoHC, TTI Bundling, DRX, SPS).
- Comparative analysis of voice quality assessment methods like PESQ and POLQA.
- Network performance testing results across the DACH region (Germany, Austria, Switzerland) for 2014.
Excerpt from the Book
2.4.1 Leveraging the Operators’ Assets
Operators should pay special attention to exploit the high quality potential telecom voice services are able to offer. In effect, carrier-grade VoIP services founded on VoLTE are at all times prioritized in the mobile network compared to other data traffic. Over the core and radio networks, QoS mechanisms are in place to care for key real-time services and their quality. Over-The-Top (OTT) VoIP services run, on the contrary, as best-effort37 data over the mobile broadband access. And here is where the codecs for HD voice play an important role: they allow MNOs to employ them (e.g. codecs) with no major side-effects on the radio frequency (RF) capacity. Moreover, operators are able to combine a certain level of HD voice even when moving to 2G/3G. This efficiency advantage means that the new codec for HD VoLTE will neither demand any improvements of the VoLTE radio infrastructure nor additional RF capacity.
Global interoperability is also a relevant operator asset to build on. Indeed, the global E.16438 community builds a distinctive entity for billions of phone users: to reach one person’s handset, wherever in the world, through the phone number is a valuable asset that telephony service providers have built over the years. In this sense, operators can benefit of a lead position over OTT opponents by further delivering interoperable voice services. Still, advancing the voice quality experience even further, mainly based on interoperable HD voice enhancements, will unleash superior advantages to all stakeholders.
Summary of Chapters
1 Introduction: Provides an overview of the shift towards all-IP network technologies and introduces VoLTE as the primary solution for future-proof telephony services.
2 Migrating to IMS-based VoLTE: Initial considerations: Discusses the market drivers for VoLTE, legacy network constraints, and the fundamental role of IMS in enabling IP-based voice communications.
3 VoLTE Parameter Optimization: Details technical optimization methods such as header compression, scheduling, and bearer prioritization to improve VoLTE performance and reliability.
4 VoLTE Testing: Analyzes the frameworks for voice quality assessment and presents empirical performance data from mobile network benchmarks in the DACH region during 2014.
5 Conclusion: Synthesizes the findings, noting that VoLTE is essential for operator competitiveness and that future efforts must focus on network roll-out, interoperability, and demand-driven growth.
Keywords
VoLTE, IMS-based VoLTE, HD voice, Mobile Network, LTE, Circuit-switched Fallback, CSFB, SRVCC, Voice Quality, POLQA, PESQ, Network Optimization, QoS, Telephony, DACH Region.
Frequently Asked Questions
What is the primary focus of this research?
The work focuses on the migration from legacy circuit-switched voice networks to packet-switched IP networks, specifically utilizing VoLTE to deliver high-quality, carrier-grade telephony.
What are the central thematic areas?
The core themes include IMS-based VoLTE architecture, network parameter optimization techniques, voice quality metrics, and performance benchmarking of real-world mobile networks.
What is the main goal or research question of the paper?
The goal is to assess the implications of introducing VoLTE from a mobile operator's perspective, focusing on how operators can optimize their infrastructure to maintain competitiveness against OTT providers.
Which scientific methods are applied in this work?
The work combines technical architecture analysis with the evaluation of empirical network test results, utilizing established benchmarks and standardized methodologies like POLQA.
What is covered in the main body of the text?
The main body covers the theoretical migration path towards VoLTE, deep dives into technical features for optimization (such as RoHC and SPS), and a comprehensive analysis of 2014 network test data from Germany, Austria, and Switzerland.
How can the work be characterized by its keywords?
The work is defined by the technical convergence of voice and IP services, characterized by terms like VoLTE, IMS, network optimization, and performance benchmarking.
Why is CSFB considered only a transition phase?
CSFB is a fallback mechanism used to support voice on legacy infrastructure while LTE is being rolled out, but it lacks the advanced multimedia and efficiency capabilities inherent in native IMS-based VoLTE.
How does VoLTE differ from OTT VoIP services?
Unlike OTT services, which operate on a best-effort basis without guaranteed QoS, VoLTE is prioritized within the operator’s network, ensuring higher reliability, lower latency, and better overall user experience.
What role does the BGCF play in the architecture?
The Breakout Gateway Control Function (BGCF) manages the routing of SIP messages to determine whether a call should be terminated in a peer IMS domain or within the CS domain.
- Quote paper
- MSc. Omar Amoretti (Author), 2016, Unleashing VoLTE capabilities. Assessing the Migration from CS Voice to IMS-based Voice over LTE (VoLTE), Munich, GRIN Verlag, https://www.grin.com/document/322492
