NOMA for 5G and Beyond Wireless Networks

Abstract

The explosive growth of wireless subscribers and high data rate demanding multimedia services have pushed the fourth-generation (4G) network to improve and adapt to the emerging issues. This has led to the evolution of cutting-edge fifth-generation (5G) wireless networks. Few of the well-known techniques for boosting 5G networks are non-orthogonal multiple access (NOMA), small cell deployment (a.k.a. HetNets), millimeter-wave (mmWave) communications, intelligent reflecting surfaces (IRSs), etc. One of the basic elements of the physical layer of a wireless network is the multiple access (MA) techniques. The MA techniques deviate in each generation and have grown from frequency division multiple access, used in the first generation, to orthogonal frequency division multiple access, which is adequately accepted in the 4G network. NOMA (MA scheme that violates the criteria of orthogonality) has been considered a promising multiple access technique for the 5G networks. NOMA supports a huge number of connected users (or devices), lowers latency, and boosts spectral efficiency. Accordingly, the application of NOMA is essential in investigating the 5G network and beyond. Furthermore, NOMA is compatible with recent techniques, such as HetNets, device to device (D2D) communication, mmWave, and IRS. This integrates NOMA with the contending 5G and beyond techniques of great research interest and is presented in this chapter. This chapter introduces a scenario in which a heterogeneous cellular network (HCN) is considered with three tiers, namely, macro base station (macroBS) tier underlaid with femto base station (femtoBS) tier, and D2D tier. NOMA principle is applied in the femtoBS tier and the D2D tier, while the macroBS tier does not use NOMA. Offloading from the macroBS tier to the femtoBS tier aids in tackling congestion at the macroBS tier. The cooperation introduced using the D2D tier further supports the offloaded macro user (macroU) from the macroBS tier. This support is primarily helpful when the femtoBS tier is using NOMA, and the femtoBS tier is unable to find a pairing user for the offloaded macroU. We introduce theoretical bounds and analysis for outage probability supported by Monte Carlo simulations. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.