Performance of NOMA with Massive MIMO for 5G

This paper investigates the integration and performance of Non-Orthogonal Multiple Access (NOMA) within 5G systems, particularly when combined with Massive Multiple-Input Multiple-Output (MIMO) and Single Carrier with Frequency Domain Equalization (SC-FDE). With the emergence of 5G technologies, supporting a massive number of Internet of Things (IoT) devices, ultra-reliable low-latency communications (URLLC), and enhanced mobile broadband (eMBB) is critical. NOMA stands out as a promising multiple access technique that enables spectrum sharing among users in the power domain, thereby improving spectral efficiency and supporting the massive connectivity needs of 5G networks. This study analyzes both conventional and cooperative NOMA schemes. In conventional NOMA, signals are decoded using Successive Interference Cancellation (SIC) based on their power levels. However, performance degradation can occur when lower-power users cannot be canceled, resulting in residual interference that affects higher-power users. To address this, cooperative NOMA is introduced, where lower-power users act as relays to transmit clean versions of higher-power users' signals, thereby exploiting spatial diversity and reducing interference. The paper evaluates the use of massive MIMO to enhance spatial multiplexing and system capacity and discusses the use of SC-FDE over traditional OFDM for its advantage in lowering Peak-to-Average Power Ratio (PAPR), especially beneficial in uplink transmissions. Two types of receivers are examined: Zero-Forcing (ZF), which nullifies interference through matrix inversion at the cost of noise enhancement and complexity, and Maximum Ratio Combining (MRC), which is less complex but sensitive to interference.

Keywords: NOMA, Cooperative NOMA, 5G, Massive MIMO, SC-FDE, SIC, ZF, MRC, BER, Spectrum Sharing, IoT, mm-Wave.