An Introduction to LTE: LTE, LTE-Advanced, SAE, VoLTE and 4G Mobile Communications, 2nd Edition

Chapter 13Quality of Service, Policy and Charging

In Chapters 2 and 11, we described how the evolved packet core transports data packets by the use of bearers and tunnels, and how it sets up a default EPS bearer for the mobile during the attach procedure. We also noted that each bearer was associated with a quality of service, which describes information such as the bearer's data rate, error rate and delay. However, we have not yet covered some important and related issues, namely how the network specifies and manages quality of service, and how it ultimately charges the user. These issues are the subject of this chapter.

We begin by defining the concept of policy and charging control, and by describing the architecture that is used for policy and charging in LTE. We continue by discussing the procedures for policy and charging control and for session management, through which an application can request a specific quality of service from the network. We conclude by discussing data transport in the evolved packet core, and offline and online charging.

Policy and charging control is described by two 3GPP specifications, namely TS 23.203 [1] and TS 29.213 [2]. The charging system is summarized in TS 32.240 [3] and TS 32.251 [4]. As usual, the details of the individual procedures are in the specifications for the relevant signalling protocols. Those for the evolved packet core are in References [5–8], but we will introduce some more protocols that are specifically related to policy ...