t locations. (b) Drive route average physical layer uplink (PUSCH) and downlink (PDSCH) throughput for six use cases. All measurements are performed on UE 4 Between RSRP and UE Transmit Power' establishes an empirical relationship between RSRP versus UE transmit power levels and Section 'Establishing Relationship Between RSRP and UE Power Consumption' compares the resulting Pcon versus RSRP with field performance. Figure 16.42a shows the range of RSRP levels assumed to define an average macro cell and small cell. Three static test locations, labelled A, B and C, are used to collect UE power consumption at the boundaries of each cell type. All field data measurements are performed using UE 4 in near free space test conditions, that is, with UE laid on a wooden table and with no surrounding objects and no user interaction to ensure that the smartphone-radiated performance is not impacted by hand or head effects. Figure 16.42b shows the average uplink and downlink physical layer throughput measured across several drive tests. LTE Small Cell Optimization Estimating UE Transmit Power Profiles One essential difference between LTE and WCDMA is the ways in which transmit power control loops operate. In WCDMA, both control and data physical channels are multiplexed at digital IQ level within the UE, the difference in spreading factors being adjusted by the NodeB using dedicated digital gains, also called 'B' factors. The resulting composite modulated carrier power is then controlled at slot rate by the NodeB to manage the rise over thermal (RoT) noise of the cell and to meet the target signal level link quality. The resulting UE transmit power density function (PDF) can then be directly mapped to the UE PTxRF transfer function, and average UE power consumption can be easily computed. This is the method used by GSMA to compute WCDMA talk time, see also examples in Reference [11]. With LTE, the uplink air interface changes the role of power control loops. First, transmis- sions within a cell are by definition orthogonal. Th