Turbo-coded Star-QAM for cooperative wireless and optical-fiber communications

A low-complexity cooperative wireless and optical-fiber communication scheme is proposed for uplink communication in a Fractional Frequency Reuse (FFR) based multicell, multiuser system. The FFR principle is invoked for improving the cell-edge performance without reducing the throughput of the cell-center. Each cell is illuminated with the aid of six Remote Antennas (RAs), which are connected to the central base-station with the aid of realistically modelled imperfect optical-fiber links. When a Mobile Station (MS) is located at the cell-edge, the two nearest RAs can be invoked to detect and forward the user´s signal to the base-station, based on the Single-Input Multiple-Output (SIMO) principle. Furthermore, we design a Turbo Coded (TC) 16-level Star-Quadrature Amplitude Modulation (StQAM) scheme for supporting optical-fiber-aided cooperative wireless transmission, where the receiver does not have to estimate the channel state information. Hence, a lower detection complexity can be achieved when compared to coherently detected schemes, albeit naturally, at a 3 dB power-loss. We also investigated the effect of phase-rotation imposed by imperfect optical-fiber links. We found that our noncoherent TC-StQAM scheme is robust to both wireless and optical-fiber imperfections.