as well its typical L1 measurement interval and the measurement's impact on UE power consumption. In this section, we discuss the most important measurements in LTE, grouping them into UE and eNode B measurements and, when appropriate, drawing an analogy with well- known WCDMA measurements. © 2009 by Taylor & Francis Group, LLC Architecture and Protocol Support for RRM 4.3.1 Measurements Performed by the User Equipment UE measurements are needed to serve the following purposes: Intra-LTE (intra- and interfrequency) cell reselection and handovers as well as inter-RAT handovers (handovers to WCDMA and GSMIenhanced data rates for GSM evolution radio access networks [GERANs]). This is because radio coverage is one of the most important mobility drivers in both idle and connected modes [14]. Admission and congestion control. Measurement-based admission and con- gestion control play an important role in maintaining service quality for end users (based on single [local] eNode B measurements). Uplink power control, scheduling, and link adaptation. These essential radio network functions are inherently adaptive and rely on fast and accurate measurements [18]. Operation and maintenance. This set of functions enables network operators to observe the performance and reliability of the network and to detect fail- ure situations. Measurements are the primary input to these functions. The UE measurement quantities follow. In addition, Figure 4.18 provides a brief overview of the required RRM measurements and their counterparts in Protocol Measurement L1 Measurement Higher Layer Purpose Analogy with Interval to Report: Filtering: WCDMA RRC/MAC Mandatory/No Reference Symbol Received Power HO, Cell Reselection CPICH RSCP (RSRP) Reference Symbol Received Quality HO, Cell Reselection 200 ms CPICH Ec/Io (RSRQ) Carrier Received Signal Strength Inter-Frequency and 200 ms UTRA RSSI Inter-RAT HO Indicator (RSSI) Channel Quality Scheduling, DL Power Control, Link 1 TTI (1 ms) Indicator (CQI) Adaptation HO: Handover MAC: Medium Access Cont