High Throughput Wireless Links for Time-Sensitive WSNs With Reliable Data Requirements

Wireless sensor networks (WSNs) and internet of things (IoT) are expected to add a massive number of wireless devices to support various emerging applications. Consequently, adopting high throughput communications protocols is indispensable to serve such a massive number of devices. Therefore, this work presents a new framework, denoted as non-orthogonal multiplexing (NOM), that can substantially improve the throughput of wireless communications links for WSNs applications. The proposed framework utilizes power domain (PD) multiplexing to improve the throughput by recognizing that the hybrid-ARQ (HARQ) protocol and Chase combining (CC) create nonuniform power requirements for the transmitted packets. Consequently, multiple data packets can be combined and transmitted simultaneously using PD multiplexing. More specifically, the proposed framework allows combining multiple new packets, or new and retransmitted packets to increase the system throughput and reduce the delay. Moreover, to overcome channel state information (CSI) feedback limitations, a simple protocol is proposed where the number of transmitted packets is fixed for all transmission sessions. Therefore, the sensing nodes do not need to identify the number of transmitted packets for each transmission slot. The obtained results show that the proposed NOM protocol can eventually improve the link throughput by 100% at high signal to noise ratios (SNRs), and hence, reduce the delay by 50%. The system complexity and overhead are generally comparable to conventional HARQ systems, which confirms the efficiency of the proposed framework.