Low-Complexity Dual-Hop D2D Design

In this paper, a novel, dual-hop, device-to-device (D2D) schemes for high-data rate and low-latency services are proposed. These schemes can be used for augmented and virtual reality applications, multimedia streaming, mobile gaming, etc. The main goal was to implement a low-complexity, energy-efficient, and low-delay processing at the relaying device (RD), while at the same time to provide an appropriate diversity gain. Decoding and full channel state information (CSI) obtaining can affect processing delay and energy consumption, thus, there is no decoding at the RD, and it doesn't need full CSI, either for receiving or transmitting. The novel full-orthogonal space-time line code (OSTLC) and full-orthogonal space-time block code (OSTBC) pair, as well as the novel quasi-orthogonal STLC (QOSTLC) and quasi-orthogonal STBC (QOSTBC) pair, for relays with four antennas, are proposed. The number of antennas at transmitting device (D1) and receiving device (D2) can be arbitrary. Furthermore, the novel processing at the RD, for increasing orthogonality within the new, full-rate, QOSTLC, i.e., for emulating full-orthogonality and improving BER performance, is proposed. Besides these novel schemes, the well-known OSTLC-OSTBC pair for relays with two antennas is considered. The simulated bit error rate (BER) results are presented for the each analyzed scheme.