A Tutorial on Nonorthogonal Multiple Access for 5G and Beyond

Abstract

Today's wireless networks allocate radio resources to users based on the orthogonal multiple access (OMA) principle. However, as the number of users increases, OMA based approaches may not meet the stringent emerging requirements including very high spectral efficiency, very low latency, and massive device connectivity. Nonorthogonal multiple access (NOMA) principle emerges as a solution to improve the spectral efficiency while allowing some degree of multiple access interference at receivers. In this tutorial style paper, we target providing a unified model for NOMA, including uplink and downlink transmissions, along with the extensions to multiple input multiple output and cooperative communication scenarios. Through numerical examples, we compare the performances of OMA and NOMA networks. Implementation aspects and open issues are also detailed.

Overview on 5G Radio Frequency Energy Harvesting

“…An illustration of NOMA mechanism is given in Figure. 5. So far, 3GPP NR has specified flexible technology framework that can be tuned to enable a wide range of 5G scenarios, and more specifications are expected for Release 16 [41].…”

Outage and ergodic sum‐rate performance of cooperative MIMO‐NOMA with imperfect CSI and SIC

“…On the other hand, the non‐orthogonal multiple access (NOMA) aims to support multiple users through non‐orthogonal resource allocation, and hence, the tradeoff between spectral efficiency and user fairness is realized. Since the NOMA outperforms the OMA schemes in terms of lower latency, larger device/mobile connectivity, higher spectral efficiency, and better user fairness, many researchers recommend NOMA as a nominee MA technique for the fifth generation (5G) and following generations of wireless communications . Especially, in the power‐domain NOMA, many users can use the whole available spectrum at the same time by allocating distinct power factors to the users opposite to their channel conditions.…”

“…Especially, in the power‐domain NOMA, many users can use the whole available spectrum at the same time by allocating distinct power factors to the users opposite to their channel conditions. However, in the downlink NOMA networks, the superposition principle is applied at the transmitter of the base station (BS), in which the mobile users' signals are combined to form one signal,whereas, at each mobile user, successive interference cancelation (SIC) is successively performed until the desired signal is obtained …”

A New Green Prospective of Non-orthogonal Multiple Access (NOMA) for 5G

“…Furthermore, NOMA scheme can be combined with many other technologies to cater the requirements of high spectral efficiency, very low latency, massive device connectivity, very high achievable data rate, ultra-high reliability, excellent user fairness, high throughput, supporting diverse quality of services (QoS), energy efficiency and reduction of operating costs expected from 5G networks [9]. Thus, NOMA incorporated technologies such as MIMO-NOMA, cooperative NOMA, NOMA, and cognitive radio (CR) and green NOMA have attracted much attention from the research community [10].Energy-efficient NOMA or green NOMA will be a key ingredient in the upcoming 5G mobile network design to cater for the goal of achieving a low cost, self-sustaining, environment-friendly wireless network. It has been observed from the Global e-Sustainability Initiative that in 2002, the mobile industry was producing around 43% of the global information and communications energy-related emissions and it is expected that this will rise to 51% by 2020 [11].…”

“…Furthermore, NOMA scheme can be combined with many other technologies to cater the requirements of high spectral efficiency, very low latency, massive device connectivity, very high achievable data rate, ultra-high reliability, excellent user fairness, high throughput, supporting diverse quality of services (QoS), energy efficiency and reduction of operating costs expected from 5G networks [9]. Thus, NOMA incorporated technologies such as MIMO-NOMA, cooperative NOMA, NOMA, and cognitive radio (CR) and green NOMA have attracted much attention from the research community [10].…”