We return to the details of the UMTS in this chapter. Many of these procedures were already presented at a high level in the discussion of radio resource control (RRC) in Chapter 7. Those examples included only two communicating entities, UE-RRC and UTRAN-RRC, but here some other participating entities are discussed. In this chapter the most common signaling procedures are shown as signaling flow diagrams. These diagrams help to illustrate how the various network entities and protocol tasks interact to perform a function. The UTRAN air interface procedures are further discussed in [1]. This chapter is rather UE-centric. Some more UTRAN-centric examples are given in [2].

Note that these diagrams do not show all the signaling needed to complete the procedure in question. Typically, part of the internal signaling of an entity (i.e., in the UE) has been left undefined in the specifications (or shown only at a high general level) and it is up to the equipment manufacturer to define the exact signaling diagrams. Therefore, some of the signal names in these diagrams have been invented by the author, and they are not based on any specification. Moreover, the procedures described here do not generally show any confirmation primitives. In real implementations these are often necessary to confirm that the requested action is possible or was successfully carried out in the applicable protocol task.

11.1 RRC Connection Procedures

The UTRAN separates the concepts of a radio connection from a radio bearer (RB). A radio connection is created...