Outage probability analysis of EH relay-assisted non-orthogonal multiple access (NOMA) systems over Block Rayleigh Fading Channel

Non-orthogonal multiple access (NOMA) has been identified as a promising multiple access technique for the fifth generation (5G) mobile networks due to its superior spectral efficiency. In this paper, we propose and investigate a Non-Orthogonal Multiple Access (NOMA) of energy harvesting (EH) relay assisted system over Block Rayleigh Fading Channel. In order to evaluate the performance of the proposed system, the integral expression of the outage probability is analyzed and derived. Numerical results confirm that our derived analytical results match well with the Monte Carlo simulations in connection with all possible system parameter

Non-Orthogonal Multiple Access (NOMA) for 5G Networks

In this chapter, we explore the concept of non-orthogonal multiple access (NOMA) scheme for the future radio access for 5G. We first provide the fundamentals of the technique for both downlink and uplink channels and then discuss optimizing the network capacity under fairness constraints. We further discuss the impacts of imperfect receivers on the performance of NOMA networks. Finally, we discuss the spectral efficiency (SE) of the networks that employ NOMA with its relations with energy efficiency (EE). We demonstrate that the networks with NOMA outperform other multiple access schemes in terms of sum capacity, EE and SE

Non-orthogonal Multiple Access (NOMA) with Asynchronous Interference Cancellation

Non-orthogonal multiple access (NOMA) allows allocating one carrier to more than one user at the same time in one cell. It is a promising technology to provide high throughput due to carrier reuse within a cell. In this thesis, a novel interference cancellation (IC) technique is proposed for asynchronous NOMA systems, which uses multiple symbols from each interfering user to carry out IC. With the multiple symbol information from each interfering user the IC performance can be improved substantially. The proposed technique creates and processes so called "IC Triangles". That is, the order of symbol detection is based on detecting all the overlapping symbols of a stonger user before detecting a symbol of a weak user. Also, successive IC (SIC) is employed in the proposed technique. Employing IC Triangles together with the SIC suppresses co-channel interference from strong (earlier detected) signals for relatively weak (yet to be detected) signals and make it possible to achieve low bit error rate (BER) for all users. Further, iterative signal processing is used to improve the system performance. Employing multiple iterations of symbol detection which is based on exploiting a priori estimate obtained from the previous iteration can improve the detection and IC performances. The BER and capacity performance analyses of an uplink NOMA system with the proposed IC technique are presented, along with the comparison to orthogonal frequency division multiple access (OFDMA) systems. Performance analyses validate the requirement for a novel IC technique that addresses asynchronism at NOMA uplink transmissions. Also, numerical and simulation results show that NOMA with the proposed IC technique outperforms OFDMA for uplink transmissions. It is also concluded from the research that, in the NOMA system, users are required to have large received power ratio to satisfy BER requirements and the required received power ratio increases with increasing the modulation level. Also, employing iterative IC provides significant performance gain in NOMA and the number of required iterations depend on the modulation level and detection method. Further, at uplink transmissions, users' BER and capacity performances strongly depend on the relative time offset between interfering users, besides the received power ratio

Cooperative Non-Orthogonal Multiple Access in 5G Systems

Non-orthogonal multiple access (NOMA) has recently received considerable attention as a promising candidate for 5G systems. A key feature of NOMA is that users with better channel conditions have prior information about the messages of the other users. This prior knowledge is fully exploited in this paper, where a cooperative NOMA scheme is proposed. Outage probability and diversity order achieved by this cooperative NOMA scheme are analyzed, and an approach based on user pairing is also proposed to reduce system complexity in practice

Trellis-Coded Non-Orthogonal Multiple Access

In this letter, we propose a trellis-coded non-orthogonal multiple access (NOMA) scheme. The signals for different users are produced by trellis coded modulation (TCM) and then superimposed on different power levels. By interpreting the encoding process via the tensor product of trellises, we introduce a joint detection method based on the Viterbi algorithm. Then, we determine the optimal power allocation between the two users by maximizing the free distance of the tensor product trellis. Finally, we manifest that the trellis-coded NOMA outperforms the uncoded NOMA at high signal-to-noise ratio (SNR)