ks, leading to frequent, small packet radio trans- missions even when screen is in its 'off' state. In active state, such as radio streaming, battery consumption depends on screen activity, streaming protocol, client payload on application processor, as well as the amount of data transferred. We propose to reduce this complexity by Focusing solely on the cellular subsystem-intrinsic contribution, that is, digital baseband (BB) modem, RF transceiver, RF front-end and associated power management circuitry, for example, DC-DC converters and envelope tracking supply modulators Restricting measurements to the LTE FDD standard in conducted test conditions, that is, loading the RF front-end with an ideal 50 Ohm load Investigating operation in LTE band 4 and 20 MHz cell bandwidth only The UE power consumption modelling presented in this section is an extension of the work presented in Reference [10] in which the LTE cellular subsystem model can be defined as Pcellular P + Midle X Pidle + MDRX PPDRX (16.1) where 'm' is a binary variable describing whether the UE is in RRC_connected (con), RRC_idle (idle) or DRX mode. The associated P value describes the power consumption in the given RRC state/mode of operation. For the sake of simplicity, only RRC-connected state measurements are presented. Beyond enabling a detailed benchmark of different chipsets, 'Pcon is also used in Section 16.8.3 to illustrate the savings that can be offered by small cell deployments. From a power consumption characterization perspective, one essential difference between WCDMA and LTE is that the LTE-flexible air interface introduces a much greater number of variables. Assessing the impact of each one on 'Pcon' can be approximated by defining two categories of transfer functions: either uplink (TX) or downlink (RX) related. Each category is then further split into a baseband and a RF subcategory. The resulting four transfer functions (PRxBB, PRxRF, PTxBB, PTxRF) are described in Figure 16.39. A test case (TC) is dedicated to assess each variable fo