riority etc., are defined in 3GPP TS 23.107 [3GP06c]. Radio Access Bearer Setup and Management Radio Access Bearer (RAB) is described by a set of parameters to transfer user data between UE (User Equipment) and CN (Core Network) for a specific traffic class. 3GPP TS 34.108 defines a set of RAB types, various RAB combinations on uplink and downlink for 3 UMTS Terrestrial Radio Access Network (UTRAN) transferring different traffic classes, and the detailed transport channel parameters for each individual uplink and downlink RAB type such as RLC PDU payload size, RLC/MAC headers, TFS (Transport Format Set), TTI (Transmission Time Interval), etc. Based on the given transport channel parameters, the maximum or peak data rate of the RAB is determined. Table 3.2 gives some examples of RAB types defined in 3GPP TS 34.108 [3GP04e] and their detailed transport channel parameters. Number of Service Peak rate Payload Transport (3GPP 34.108) [kbps] [bit] [bit] Blocks Conversational/Speech/U CS 12.2 L 12.2 kbps/ CS RAB Conversational/unknown/ CS 64 DL 64 kbps/ CS RAB Interactive or PS 64 background/DL 64 kbps / PS RAB Interactive or PS 128 background/DL 128 kbps / PS RAB Interactive or PS 384 background/DL 384 kbps / PS RAB Table 3.2: RABs defined in 3GPP TS 34.108 [3GP04e] (In this table, CS refers to Circuit-Switched and PS refers to Packet-Switched) The selection of an appropriate RAB for a particular user connection is mainly determined by Radio Resource Management (RRM) functions applied in the RNC and delimited by the parameters provided by the SGSN during the RAB establishment request. The core network will select a RAB with appropriate QoS based on the service request from the subscriber, and ask the RNC to provide such a RAB. The RAB is chosen depending on the user subscription, service type, requested QoS, the radio situation like pathloss, power utilization within the cell, interference power, etc. For example, the interactive web application can be assigned RAB 64kbps or higher. Conversational voice usually applies