LTE Small Cell Optimization

14 VoLTE Optimization

Riku Luostari, Jari Salo, Jussi Reunanen and Harri Holma

1. 14.1 Introduction
2. 14.2 Voice Options for LTE Smartphones
3. 14.3 Circuit Switched Fallback
4. 14.4 Voice over LTE
5. 14.5 Single Radio Voice Call Continuity
6. 14.6 Summary
7. References

14.1 Introduction

LTE radio is designed for the packet connections without any support for circuit switched (CS) connections. Therefore, other voice solutions for voice service are required instead of the traditional CS voice. The voice service is important from the operator revenue point of view even if the share of voice traffic from the data volume point is very low. Every single LTE-capable smartphone needs to have a solution for offering high-quality voice connection. The different voice options including CS fallback and voice over LTE (VoLTE) are presented and the optimization is discussed in this chapter. Section 14.2 illustrates the timing and the main differences of the voice options. Section 14.3 presents CS fallback and Section 14.4 VoLTE solution. The handover from VoLTE to CS voice is called single radio voice call continuity (SRVCC) and is discussed in Section 14.5. The chapter is summarized in Section 14.6.

14.2 Voice Options for LTE Smartphones

The first LTE smartphones used dual radio solution where the terminal included two parallel radios: one for CDMA voice and another for LTE data. It looks like two separate terminals from the network point of view. Such a solution is simple from the network point of view ...