Uplink non-orthogonal multiple access for 5G wireless networks

The increasing demand of mobile Internet and the IoTs poses exacting requisites for 5G wireless communications, like high spectral efficiency. Hence, a promising technology, non-orthogonal multiple access (NOMA), is discussed. Unlike standard orthogonal multiple access technologies, NOMA can serve much more users via non-orthogonal resource allocation. The most striking attribute of NOMA is to serve multiple users at the same time/frequency/code, but with different power levels, which produces a remarkable spectral efficiency gain. There are mainly two types of NOMA techniques, power-domain and code-domain. This paper primarily focuses on power-domain NOMA that utilizes superposition coding (SC) at the transmitter and successive interference cancellation (SIC) at the receiver. Also, this paper discusses how NOMA performs when it is combined with other wireless communication techniques, for example cooperative communications, multiple-input multiple-output (MIMO). Furthermore, this p...

ATBU Journal of Science, Technology and Education, 2019

As a result of increasing demand on telecommunications services, networks suffer low speed and high latency. These seriously affect the performance of the network due to the presents of high burden on the existing multiplexing techniques such as Orthogonal Multiple Access (OMA) to deliver high speed data rates. Hence, the ever increasing demand for high speed and low latency data communications by mobile users define future features of networks to ease the burden on the existing multiple access techniques by significantly offering high data rates through multiplexing of multiple users over the same channel at the same time and frequency using Non Orthogonal Multiple Access (NOMA) in 5G systems. The research developed an improved resources allocation scheme for NOMA fifth Generation (5G) systems. The multiplexing of users on the same frequency band in NOMA makes it possible to have higher sum rate than the conventional OMA technique. This high sum rate can only be guaranteed through ...

International Journal of Electrical and Computer Engineering (IJECE), 2020

One of the hot research topics for the upcoming 5G (fifth-generation) wireless communication networks is the non orthogonal multiple access (NOMA) systems, where it have attracted both industrial and academic fields to improve the existing spectral efficiency. In fact, the multiuser detection process for NOMA systems is largely affected by the power distribution of the received signals. In this paper, a new method has been proposed to control the transmit power among active users in one of the promising NOMA systems; the interleave division multiple access (IDMA) which has been adopted here for consideration. Unlike conventional methods, where tedious mathematical computations are required; a simple and direct method has been derived. The proposed method has been applied to IDMA system with different FEC codes. The obtained results show that the proposed method outperforms the conventional one as compared to optimal results.

Wireless Personal Communications, 2015

This paper investigates several new strategies for the allocation of radio resources (bandwidth and transmission power) using a non-orthogonal multiple access (NOMA) scheme with successive interference cancellation (SIC) in a cellular downlink system. In non-orthogonal access with SIC, the same subband is allocated to multiple users, which requires elaborate multiuser scheduling and subband assignment techniques, compared to orthogonal multiplexing. While taking into account various design issues, we propose and compare several optimum and suboptimum power allocation schemes. These are jointly implemented with multiple user scheduling strategies. Besides, a minimization of the total amount of used bandwidth is targeted. Also, to increase the total achieved system throughput, a hybrid Orthogonal-Non orthogonal scheme is introduced. This hybrid scheme enables a dynamic switching to orthogonal signaling whenever the non-orthogonal cohabitation in the power domain does not improve the achieved data rate per subband. Extensive simulation

Academic Journal of Nawroz University

Because of the arising requirements of emerging networks (Fifth generation and beyond) such as supporting diverse Quality of Services (QoS), low latency, and high spectral efficiency; the previous and traditional generations of communication systems are becoming inappropriate. Furthermore, due to the huge connectivity and ever-growing demands of diverse services and high data rate applications, more effective radio access techniques are required for the purpose of a full-scale implementation of the fifth generation (5G) and beyond wireless systems. Therefore; the researchers are looking for new mechanisms to accomplish these demands, and one of the key techniques been proposed is NOMA due to its capability of spectrum efficiency enhancement. In NOMA-Based systems, the information signals of various users are superimposed at the transmitter side, by utilizing the differences of channel gain to work for different users simultaneously. In this study, recent papers on resource allocatio...

IEEE Communications Surveys and Tutorials, 2018

In the 5th generation (5G) of wireless communication systems, hitherto unprecedented requirements are expected to be satisfied. As one of the promising techniques of addressing these challenges, non-orthogonal multiple access (NOMA) has been actively investigated in recent years. In contrast to the family of conventional orthogonal multiple access (OMA) schemes, the key distinguishing feature of NOMA is to support a higher number of users than the number of orthogonal resource slots with the aid of non-orthogonal resource allocation. This may be realized by the sophisticated inter-user interference cancellation at the cost of an increased receiver complexity. In this article, we provide a comprehensive survey of the original birth, the most recent development, and the future research directions of NOMA. Specifically, the basic principle of NOMA will be introduced at first, with the comparison between NOMA and OMA especially from the perspective of information theory. Then, the prominent NOMA schemes are discussed by dividing them into two categories, namely, power-domain and code-domain NOMA. Their design principles and key features will be discussed in detail, and a systematic comparison of these NOMA schemes will be summarized in terms of their spectral efficiency, system performance, receiver complexity, etc. Finally, we will highlight a range of challenging open problems that should be solved for NOMA, along with corresponding opportunities and future research trends to address these challenges.

2017

IEEE Internet of Things Journal, 2019

In this paper, energy efficient resource allocation is considered for an uplink hybrid system, where non-orthogonal multiple access (NOMA) is integrated into orthogonal multiple access (OMA). To ensure the quality of service for the users, a minimum rate requirement is pre-defined for each user. We formulate an energy efficiency (EE) maximization problem by jointly optimizing the user clustering, channel assignment and power allocation. To address this hard problem, a many-toone bipartite graph is first constructed considering the users and resource blocks (RBs) as the two sets of nodes. Based on swap matching, a joint user-RB association and power allocation scheme is proposed, which converges within a limited number of iterations. Moreover, for the power allocation under a given user-RB association, we first derive the feasibility condition. If feasible, a low-complexity algorithm is proposed, which obtains optimal EE under any successive interference cancellation (SIC) order and an arbitrary number of users. In addition, for the special case of two users per cluster, analytical solutions are provided for the two SIC orders, respectively. These solutions shed light on how the power is allocated for each user to maximize the EE. Numerical results are presented, which show that the proposed joint user-RB association and power allocation algorithm outperforms other hybrid multiple access based and OMA-based schemes. Index Terms-Non-orthogonal multiple access (NOMA), energy efficiency (EE), power allocation (PA), uplink transmission. I. INTRODUCTION Non-orthogonal multiple access (NOMA) has been considered as a promising candidate for the fifth generation (5G) and beyond 5G cellular networks [2]-[7]. The key idea of NOMA is to serve multiple users simultaneously over the same radio resources. The introduced inter-user interference is mitigated by employing successive interference cancellation (SIC) at the receiver. Downlink NOMA has been extensively studied so far. Some works target sum rate maximization and show that higher spectral efficiency (SE) can be achieved by NOMA when compared with conventional orthogonal multiple

2020 International Symposium on Networks, Computers and Communications (ISNCC), 2020

5G is the fifth generation technology standard for cellular networks, which is already being deployed and offering many advantages for communications, such as the high degree of flexibility, the possibility of management and control of systems and resources, thus allowing to host and execute services in one or more distinct network slices, etc. Non-orthogonal multiple access (NOMA) is being considered as a key enabling technique for 5G cellular systems. The earlier generations are becoming less practical with the emergent requirements such as very high spectral efficiency, very low latency, supporting diverse quality of services (QoS). Researchers are working on different techniques to fulfill these requirements, and NOMA is one of the essentials due to its capacity to increase spectrum efficiency. NOMA schemes exploit channel gain differences to serve multiple users concurrently, by superimposing multiple users' information signals at the transmitter side. In this paper, we review, analyze and classify recent papers on resource allocation problem in 5G networks, and then we discuss the proposed solutions. In particular, the papers are classified into two main categories: power/energy-efficient and rate-optimal. For each paper, the objective, optimization method and main results are discussed. Finally, some open challenges are highlighted.

2018

Representing the next generation wireless network, non-orthogonal multiple access (NOMA) has become crucial multiple accessing techniques in recent times. In this article, the core issue of NOMA system, allocating power to multiple users has been addressed. In NOMA, the increment in the power of one user increases the interference of other users because all the users utilize the same frequency band but distinguish by their power level. To cancel the signals of other users at reception, users must perform successive interference cancellation (SIC) by handling other users' signals as noise and finally decode its own signal. Incompetent power allocation could upturn the interference greatly, which decreases the data rate and user fairness, the result is degradation of the system capacity and unfair user data rate. Simulation results showed that power allocation of each user has a great impact on other users' data rate and total system capacity. In this article computational app...