, 2 X 2 X 2 AC performs better than 1 x 2 x 2 AC with a SNR gain of 2 3 dB. For an outage of 10-2, 1 x 2 x 2 and 2 x 2 x 2 ACs have a SNR gain of ~ 20 dB over {1, 1, 1} AC. This illustrates the improvement of system performance with MIMO antennas. 6.4.3.2 Impact of Feedback Delays In Fig. 6.7, the impact of feedback delays is visualized with respect to (a) over the outage probability at 15 dB SNR for a 2 X 2 X 2 AC with FPs {1, 1, 1}. Curves demonstrate the severity of feedback delays over the outage probability with respect to a. For a < 0.4T, system records lower outage probability with better performance. However, with a decrease in PPQ, outage probability increases and results in system performance degradation. Curves illustrate for a < 0.1, system with {0.1,0.1,0.1} CP records high outage probability over the other CPs values. Further, system with {0.9, 0.9, 0.9} CP has low outage probability for a < 0.5T. It 6 Energy Harvested Device-to-Device MIMO Systems for Beyond 5G Time fraction (a) Fig. 6.7 2 x 2: X 2 MIMO AC: Outage probability VS (a) for different p values [14] is noticed that system performance improves with the decrease in aT due to more IP time. 6.4.3.3 Throughput Analysis In Fig. 6.8, throughput VS SNR curves are plotted for a 1 x 2 x 2 AC with FPs {2, 1, 1}. Throughput is analyzed at two fixed transmission rates Rr = 1 and Rr = 2 bits/s/Hz and with a = 0.2T. Curves illustrate the increase in system throughput with the increase in Rr at high SNR. System with {0.9,0.9,0.9} CP with an SNR gain of 2 5 dB attains higher throughput prior to {0.1,0.1,0.1} CP. For Rr = bits/s/Hz, system with {0.9,0.9,0.9} and {0.1,0.1,0.1} CPs, throughput saturates to 0.8 at 38 dB and 43 dB, respectively, whereas for Rr = 1 bits/s/Hz, system throughput saturates to 0.4 at 10 dB and 15 dB, respectively. 6.5 Conclusion In this chapter, concepts of energy harvesting are discussed such as energy harvesting sources, energy transmission techniques, energy harvesting models, and the impact of channel estimation errors over SW