NON-ORTHOGONAL MULTIPLE ACCESS WITH V-BLAST UNDER OPTIMUM ORDERING

Wireless communication has undergone many changes since its invention. Various multiple access techniques are developed and applied to perform communication through channels. Frequency-division multiple access (FDMA), time-division multiple access (TDMA), and code-division multiple access (CDMA) are the basis structures of the first three generations in wireless communication. In these schemes, orthogonal resource blocks are shared among distinct users. As an non-orthogonal multiple access method, non-orthogonal multiple access (NOMA) offers improved error and spectral efficiency performance by making it possible for all the users to benefit from the same frequency band at the same time slot. NOMA can be implemented as either power-domain or code-domain. Successive interference cancellation (SIC) is the fundamental idea behind the power-domain NOMA technique by using channel state information (CSI). Users can decode all transmission signals and force the interuser-interference to zero by applying SIC. By realizing communication through different channel states, multiple-input multiple-output (MIMO) enables enhanced data rate and/or error probability performance over wireless communication channels. In this thesis, a thorough combination of MIMO and the power-domain NOMA techniques is presented by applying zero-forcing (ZF) Vertical Bell Laboratories Layered Space-Time (V-BLAST) architecture in a multiuser downlink scenario. With ZF V-BLAST, layered transmission is conducted in spatial domain and SIC is carried out at the users such that spectral efficiency is improved. The Rayleigh channel model which is an effective way to simulate when there is no line-of-sight and the Nakagami-m channel model which is a general model are investigated for the proposed MIMO-NOMA scheme with ZF V-BLAST. The performance of the recommended system is compared with the conventional approach in terms of the average sum rate (ASR). Under the presented technique, optimum ordering is applied and carried out at the users. In this way, SIC is performed by comparing the signal-to-noise ratio (SNR) of each signal. The related SNR is signature of each transmit antenna. The effect of applying optimum ordering manifests itself as a 3 dB SNR gain in outage probability.