The increasing gap among capacity and demand poses an important call for novel network technologies to allow mobile operators to improve performance (from the end-users’ point of view) on a cost-effective basis. In fact, Voice over Long Term Evolution (VoLTE) is a key component for an innovative set of base services defined for all-IP networks: the objective relies on making such new services as accessible as voice and SMS are nowadays, while also offering a flexible interaction with Internet applications.
Indeed, LTE focus on a (rather flat) all-IP access technology aiming at delivering a bandwidth-efficient method of carrying multiple types of user traffic at the same time. In other words, the capability of deploying Voice over IP (VoIP) services, while also supporting high-rate data throughputs, characterizes one of the critical drivers for the development to LTE.
Within this context, the IP Multimedia Subsystem (IMS) and Session Initiation Protocol (SIP) are essential technologies for deploying VoIP in an LTE setting. Nevertheless, the LTE RAN features are ultimately responsible for creating ‘value added’ services in relation to VoIP. Therefore, this paper illustrates in the second chapter the advantages of the IMS-based VoLTE approach as well as its (strategic) positioning compared to initial methods and over-the-top (OTT) providers.
Furthermore, the third chapter explains that optimization of radio features and parameters is required to offer reliable VoLTE connections based on high success rates. This is especially important for highly-competitive markets like the Austrian telecommunication sector: annual network performance tests (conducted by the P3 Group for example) may unmask a mobile operator’s (network) vulnerabilities and critically influence its customer’s preference and the likely churn rate. Finally, conclusions are drawn based on the key findings described in this paper.
Table of Contents
1 Introduction
2 Migrating to IMS-based VoLTE: Initial considerations
2.1 Benefits of IMS-based VoLTE
2.2 Positioning VoLTE
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 Conclusion
Objectives and Scope
The paper examines the implementation of Voice over LTE (VoLTE) and identifies essential radio access network (RAN) optimization techniques required to ensure carrier-grade voice quality and service reliability in an all-IP network environment.
- Strategic advantages of migrating to IMS-based VoLTE.
- Comparative analysis of VoLTE versus legacy fallback methods and OTT solutions.
- Technical optimization of key RAN parameters for improved performance.
- Resource management strategies for real-time voice traffic.
- Enhancing user experience through QoS and battery-saving features.
Excerpt from the book
3.2 Transmission Time Interval (TTI) Bundling
LTE presents a shorter TTI (1ms subframe) than earlier defined in cellular technologies. Clearly, a smaller TTI enables low over-the-air latency for real-time applications as resource scheduling is performed for every TTI. Some uplink issues are, though, caused by the short TTI in particular settings of an eNodeB’s coverage: given a UE located at a cell edge (with deteriorating reception and no possibility of enhancing its transmission power), the eNodeB may activate the TTI bundling. In other words, the UE will intensify the error detection and correction related to each data broadcast by transmitting over several TTIs. Based on this improved approach (e.g. error detection/correction), overall latency is diminished compared to the use of a single TTI.
As presented in Fig. 5, TTI bundling contributes to lower-latency VoLTE data at cell edges, where information errors are predictable. Instead of waiting for the HARQ process (typically 8ms/period) to send a data retransmission request, a data retransmission is assumed by TTI bundling: by doing so, several data packets are filled into a HARQ interlace period in advance. As a result, every packet comprises the identical source data coded with 4 distinct groups of error detection/correction bits.
Generally speaking, the short 1ms TTI (along with its bundling approach) represents for VoLTE a considerable advantage: it improves the uplink performance at cell edges by means of multiple bundled TTIs to transfer higher error detection and correction information.
Summary of Chapters
1 Introduction: Provides an overview of the shift toward all-IP networks and outlines the necessity of VoLTE for mobile operators.
2 Migrating to IMS-based VoLTE: Initial considerations: Discusses the market drivers for VoLTE and compares it with alternative strategies like CSFB and OTT solutions.
2.1 Benefits of IMS-based VoLTE: Details the competitive advantages of VoLTE, including HD voice quality and integration with web services.
2.2 Positioning VoLTE: Analyzes the strategic necessity of adopting VoLTE compared to provisional voice methods in LTE devices.
3 VoLTE Parameter Optimization: Explores technical steps required to enhance VoLTE performance and service reliability.
3.1 Robust Header Compression (RoHC): Explains how RoHC reduces bandwidth consumption by condensing protocol headers.
3.2 Transmission Time Interval (TTI) Bundling: Describes a method for improving uplink performance at cell edges by reducing retransmission latency.
3.3 Discontinuous Reception (DRX): Examines techniques for conserving UE battery life during voice calls by utilizing silent periods.
3.4 Dedicated Bearers: Discusses the use of EPS bearers to ensure quality of service for real-time voice packets.
3.5 Semi-Persistent Scheduling (SPS): Details how SPS minimizes control channel overhead for steady voice traffic transmissions.
4 Conclusion: Summarizes the findings and reinforces the long-term strategic value of VoLTE for telecom operators.
Keywords
VoLTE, LTE, IMS, SIP, RAN, Optimization, QoS, RoHC, TTI Bundling, DRX, Dedicated Bearers, SPS, VoIP, Mobile Broadband, Network Performance
Frequently Asked Questions
What is the core focus of this paper?
The paper focuses on the technical and strategic requirements for implementing Voice over LTE (VoLTE) and how to optimize Radio Access Network (RAN) parameters to achieve high-quality voice services.
What are the primary themes discussed?
Key themes include the migration to all-IP networks, the comparison between VoLTE and legacy or OTT voice solutions, and specific radio optimization techniques like RoHC, DRX, and SPS.
What is the main objective of the author?
The primary goal is to demonstrate that VoLTE is the superior strategy for mobile operators to improve network performance and customer experience in competitive markets.
Which scientific methods or approaches are used?
The paper utilizes a technical analysis approach, examining LTE architectural standards, standardized QoS Class Identifier (QCI) values, and radio resource management strategies.
What does the main body cover?
The main body covers the initial considerations for migration, the competitive positioning of VoLTE, and detailed technical sections on parameter optimization for reliable voice connectivity.
Which keywords best characterize this work?
Keywords include VoLTE, LTE, IMS, RAN Optimization, QoS, TTI Bundling, and Semi-Persistent Scheduling.
How does TTI Bundling specifically benefit VoLTE?
TTI Bundling improves uplink performance for users at cell edges by allowing the transmission of error correction information over multiple TTIs, thereby reducing latency and retransmission needs.
Why are Dedicated Bearers important for VoLTE?
Dedicated Bearers are critical because they allow operators to isolate voice traffic from generic data traffic, ensuring that voice packets receive the necessary QoS treatment to avoid latency and packet loss.
What role does DRX play in VoLTE?
DRX helps conserve the battery life of the User Equipment (UE) by switching off certain components during the periods of silence in a voice conversation.
- Quote paper
- Omar Amoretti (Author), 2015, VoLTE Capabilities. RAN Optimization Requirements, Munich, GRIN Verlag, https://www.grin.com/document/300821
