n terms of diversity, the various MIMO schemes, such as transmit diversity, spatial multiplexing, and multiuser MIMO, play a key role. 4.2 Radio Resource Management Procedures In order to meet the RRM related requirements for LTE, 3GPP TS 36.300 [14] and 3GPP TR R3.018 [16] list the RRM functions that need to be supported in LTE. In this chapter, we list and discuss these functions with the understanding that the interplay of the various RRM functions is an important aspect, although it is typi- cally not subject to standardization. For instance, ICIC may result in limitations in the usage and power setting of certain resource blocks that affect the operation of the dynamic resource allocation (scheduler). Also, radio bearer control may have an impact on the operation of RAC by manipulating threshold values that the RAC takes into account when making an admission decision. Likewise, at the time of writing, the interaction between intercell power control relying on overload indi- cation and intercell interference coordination relying on traffic load indication is currently under study by the 3GPP. 4.2.1 Radio Bearer Control (RBC) and Radio Admission Control (RAC) The establishment, maintenance, and release of radio bearers (as defined in 3GPP TR 25.813 [17]) involve the configuration of radio resources associated with them. When setting up a radio bearer for a service, RBC takes into account the over- all resource situation in LTE, the QoS requirements of in-progress sessions, and the QoS requirement for the new service (see Figure 4.3). RBC is also concerned with the maintenance of radio bearers of in-progress sessions at the change of the © 2009 by Taylor & Francis Group, LLC Architecture and Protocol Support for RRM eNode B Create dedicated bearer request [QoS Info] RAC takes place upon a EPS radio QoS Info (depending on service type): bearer setup request Label (~QoS Class Identifier) GBR/MBR/AMBR UL/DL packet filters PHY radio BS establishment involves EPS bearer setup request the evaluation and the reservati