Spectral efficiency enhancement technologies for future reliability-aware wireless communication systems

): In order to make better use of the limited spectrum resources and satisfy the requirements of extremely low error probabilities, spectral efficiency and reliability are considered as two major concerns for future wireless communication systems. Although various technologies have been proposed and examined to enhance the spectral efficiency effectively, the reliability performance of them has not yet been investigated thoroughly and well improved. In this work, we consider four dominating spectral efficient technologies, i. e., power-domain non-orthogonal multiple access (PD-NOMA), sparse code multiple access (SCMA), multi-input multi-output (MIMO) and orthogonal frequency division multiplexing (OFDM) systems. For the PD-NOMA and the SCMA networks, most of the existing designs only focus on maximising the network throughput, while reliability requirements of the users have not been well investigated. For the MIMO and OFDM systems, although many techniques have been proposed and evaluated to reduce the transmission error probabilities, there is still a significant room for increasing the reliabilities as well as decreasing the complexities of these techniques. Thus, we are motivated to study these theologies and provide our reliability-aware designs. The contribution of this work can be generalised into the following two aspects. On the one hand, we provide system designs to satisfy different reliability requirements from the network level of wireless communication systems, i. e., obtaining optimal resource allocation schemes. On the other hand, from the point-to-point transmission level, we focus on developing the transmission and reception techniques for these technologies so that their reliabilities can be further enhanced, i. e., reducing error probabilities.