re [9], if supported by the system. Of course, the eNodeB is capable of measuring uplink SINR which could be used to trigger handover in case uplink quality drops. Even if the calculation of SINR is supported by the system for connected mode, SINR cannot be used as a trigger for idle mode, which makes controlling of 'ping-pong' difficult. RSRQ: This is a function of cell RSRP, own cell load, other cell interference and thermal noise power. In principle, downlink SINR can be estimated from RSRQ, which in turn allows approximate mapping of RSRQ to downlink throughput, if the cell load is known. RSRP: This is independent of own cell load, interference and thermal noise. RSRP is basically a path loss8 measurement and as such insensitive to network load changes, unlike RSRQ which fluctuates based on own and other cell load. Thus, the main drawback of RSRP is that it cannot be used to estimate SINR, except in an isolated cell without other cell interference. A systematic way to approach the inter-layer mobility design problem is to first choose a minimum acceptable uplink- and downlink-scheduled throughput for each layer and then map the chosen throughput target to SINR, RSRQ or RSRP thresholds. Often the decision of which measurement quantity to use in the mobility design is made considerably easier by the constraints of the eNodeB implementation which commonly supports only a subset of measurement triggers discussed thus far. 8 In this section the term 'path loss' is used in the 3GPP sense to mean the difference between reference signal transmit power and RSRP, in other words antenna system gain is included. For 3G, the corresponding path loss measure is the difference between CPICH transmit power and RSCP. Inter-layer Mobility Optimization 15.4.2 Mapping Throughput Target to SINR, RSRQ and RSRP The basic design question is to determine the minimum required service level, below which the UE should exit the layer by, for example, handover, redirect or idle mode reselection. In most business environments, the question 