r each function. For example, TC 1 investigates the impact of modulation and coding scheme (MCS) on PRxBB while all other variables are held constant. Figure 16.39 also shows the experimental setup. Smartphones are tested in a faraday cage and are connected to an eNodeB emulator (Anritsu 8820c) via a pair of coaxial cables. Both supply voltage and current consumption are acquired over at least 30 seconds per point by an Agilent N6705B power supply. The measurements accuracy is estimated at +10 mW and are performed with screen maintained in its 'Off' state. Figure 16.40 presents the characteristics of the benchmarked smartphones. With the excep- tion of UE 3, all UEs are high-end flagship devices. The selection is representative of two LTE Small Cell Optimization Downlink parameters Uplink parameters Sub-category Transfer Category (impact of) function MCS / PRBs [0,28] Baseband PRxBB in SISO and MIMO [0,100] RF power SISO/MIMO [-25,-90] [0,100] Baseband PTxBB [0,23] RF power QPSK / 16 QAM PTxRF [-40,23] Anritsu 8820c Agilent N6705B RF1 in/out Tx/R x1 Power DC supply R F2 out Figure 16.39 LTE chipset power consumption test cases and experimental setup. Test case 2 is volun- tarily omitted for the sake of clarity. Variables are shown in brackets generations of baseband modems and three generations of RF transceivers. The devices also allows for comparing two PA control schemes: Average Power Tracking/Gain Switching (APT/GS) in UEs 1, 2 and 3, versus the recently introduced Envelope Tracking (ET) in UEs 4 and 5. The test results shown in Figure 16.41 reveal several remarkable findings. Starting with PRXBB performance in Figures 16.41a and 16.41b (TC1), it can be observed that baseband decoding energy efficiency has significantly improved in UEs 3 and 4 versus UEs 1 and 2. In 2x2 MIMO operation, the average power consumption slope is nearly halved, from 1 mW per Mbps, to approximately 0.4 mW per Mbps. For example, at 80 Mbps, UE 4 power consumption is 33% better than that of UE 1. This means that operating UEs 3 and 4