On Performance of IoT Devices Utilizing Energy Harvesting and Carrier Sensing in NOMA-HCN

This work proposes a energy harvesting based non-orthogonal multiple access (NOMA) scheme in a heterogeneous cellular network (HCN) to support a ultra-dense network of devices. HCN comprises of macro-cell (MC) tier under-laid by small-cell (SC) tier. The distribution MCs follow the independent Poisson point process model, while the SC tier employs carrier sensing. Carrier sensing reduces interference by allowing only one base station to transmit. The analysis is carried out at SC which pairs two Internet-of- Things (IoT) devices for downlink NOMA transmission. IoT devices have diversified energy profiles and channel conditions which makes them suitable for NOMA pairing. Wireless energy harvesting and cooperative communication is employed at the devices to compensate for the energy and increasing coverage to IoT devices. Unlike previous works, the proposed method employs EH employing interference from SC and M C tiers rather than just the superimposed signal for EH. Expression of outage probability and system throughput are derived for the proposed NOMA transmission and comparisons are drawn with the HCN that do not employ carrier sensing.