discussed in the sections focusing on the particular RRM function later in this chapter. We can differentiate the following main RRM functions in LTE, each of which will be discussed separately in Section 4.2: radio bearer control (RBC) and radio admission control (RAC); dynamic packet assignment-scheduling, link adaptation and power allocation; handover control; intercell interference coordination; load balancing; MIMO configuration control; and MBMS (multicast broadcast multimedia services) resource control. 4.1.3 Radio Resource Related Requirements Prior to the development of the LTE concept, the 3GPP defined a number of require- ments that this new system should fulfill. These requirements vary depending on © 2009 by Taylor & Francis Group, LLC Long Term Evolution: 3GPP LTE Radio and Cellular Technology whether they are related to the user perceived performance or to the overall system efficiency and cost. Accordingly, there are requirements on the peak user data rates, user plane and control plane latency, and spectrum efficiency. The requirements on the spectral efficiency or on the user throughput including average and cell edge throughputs are formulated as relative measures to baseline HSPA (high-speed packet access)-that is, the 3GPP release-6 standards suite-performance. For example, achieving a spectral efficiency and user throughput of at least two to three times that of the HSPA baseline system is required. The downlink and uplink peak data rates should reach at least 100 and 50 Mb/s (in a 20-MHz band), respectively. For the full set of requirements, see reference 6. It is clear that fulfilling such requirements can be possible only with highly efficient radio resource management techniques able to squeeze out the most from the instantaneous radio link conditions by adapting to the fast fluctuations of the radio link and by exploiting various diversity techniques. With respect to adapting to radio link fluctuations, fast link adaptation and link quality dependent schedul- ing have high importance; i