4.1 Introduction

In this chapter we discuss the radio resource management (RRM) functions in long term evolution (LTE). The term radio resource management is generally used in wireless systems in a broad sense to cover all functions that are related to the assignment and the sharing of radio resources among the users (e.g., mobile terminals, radio bearers, user sessions) of the wireless network. The type of the required resource control, the required resource sharing, and the assignment methods are primarily determined by the basics of the multiple access technology, such as frequency division multiple access (FDMA), time division multiple access (TDMA), or code division multiple access (CDMA) and the feasible combinations thereof. Likewise, the smallest unit in which radio resources are assigned and distributed among the entities (e.g., power, time slots, frequency bands/carriers, or codes) also varies depending on the fundamentals of the multiple access technology employed on the radio interface [23].

The placement and the distribution of the RRM functions to different network entities of the radio access network (RAN), including the functional distribution between the terminal and the network as well as the protocols and interfaces between the different entities, constitute the RAN architecture. Although the required RRM functions determine, to a large extent, the most suitable RAN architecture, it is often an engineering design decision how a particular RRM function should be realized. For example, whether intercell interference coordination or handover control is implemented in a...