The purpose of this paper is to provide a high-level overview of the most important non-orthogonal multiple access (NOMA) protocols in 5G and 6G networks that incorporate code division within the context of 3GPP standardization. The article’s objective is also to look into and compare the various strategies that have been proposed as a solution to the issue of resource distribution to achieve high performance. Many different NOMA plans for 5G and 6G systems have been suggested by a multitude of businesses. NOMA is currently developing in two primary directions: one of them is with power division, and the other is with code division. During the process of standardization carried out by the 3GPP, the attention of the developers was concentrated in the second direction for the application of NOMA schemes in 5G and 6G systems. Hardware communication, also known as D2D communication, performs a significant role in the process of communication between devices. This will increase the efficiency with which network resources are utilized. Devices are now able to interact directly with one another, avoiding the need for transmission nodes. It also serves as one of the approaches to the problem of limited network coverage, which can be improved by utilizing D2D, and as a result fees and energy can be reduced. Increasing the size of the network is one way to achieve this goal, the explained of NOMA technology as well as its primary benefits in wireless technology. The most common variants of code division NOMA and the characteristics of those variants are discussed, as well as the opportunities and challenges associated with implementing those variants. NOMA protocols allow continuous expansion of wireless communication networks, i.e., 5G and 6G, which leads to enhanced performance of the networks.

The exponential development of wireless applications has increased problems in the spectrum. The unlicensed frequency spectrum is becoming highly saturated, in order to support the conditions of new radio devices with increasing data rates. The spectrum that has previously been allocated is also unused. As a consequence of these developments, scientists have been putting a lot of effort into developing an approach to the issue of the limited spectrum that could make it possible to create a more effective utilization of it. As cognitive radio permits opportunistic use of the licensed spectrum in less crowded areas, it has been proposed as a solution to this challenge. This paper provides an overview of the cognitive radio environment, including a dynamic spectrum access strategy, as well as additional information on the cognitive capabilities operating in combination IoT communication technologies. We investigate the utilization of cognitive radio in the Internet of Things along with the significant role that cognitive radio plays in making the Internet of Things possible. Cognitive radio will provide a comprehensive examination of spectrum sensing, which will cover the many types of sensing, sensing that is based on machine learning, as well as open topics that still need to be addressed further in this sector. This research paper is written in a way that provides detailed instructions for the purpose of assisting new researchers in the area of Cognitive Radio Networks.

The results of development of a mathematical model for time-frequency resource allocation in the LTE technology downlink using Resource Allocation Type 1 are given. Using the proposed model allows taking into account the technological features of the LTE downlink (splitting the resource blocks into subsets, allocation of RB of only one subset to user equipment), as well as territorial remoteness of user equipment (type of modulation system and coding). During the analysis it was found that use of the proposed model is aimed at providing each user equipment with quality of service according to the bandwidth in the downlink with the possibility of access to additional (unguaranteed) bandwidth. The analysis of the proposed model for time-frequency resource allocation in the LTE technology from the viewpoint of providing the required bandwidths for user equipment in the downlink was conducted.

Based on the laws of the known mechanisms of the frequency resources scheduling in the download channel, solution of the problem raised in this paper assures QoS by available resources which directly influent on quality of design of the equipment. The WiMAX resource allocation algorithms determine which users to schedule, how to allocate subcarriers to them, and how to determine the appropriate power levels for each user on each subcarrier. We present a brief survey of recent scheduling research. The goals of scheduling are to achieve the optimal usage of resources, to assure the QoS. The mathematical model introduced by a number of linear and nonlinear conditions-limitations is analyzed in this research, Therefore, a model is proposed that consists in the statement of the sub-channels scheduling problem. This model gives solutions of problems of rescheduling of the accessible capacity of the download channel of the WiMAX technology for the information transmission in the direction of users stations, taking into account their territorial remoteness.

In cognitive radio systems, users that are cognitive (unlicensed) must constantly scan the spectrum for primary (licensed) users to be present. In this article, the researchers display the benefits of cognitive radio collaboration. It is demonstrate that detection times can be reduced by motivating cognitive users to cooperate in the same band, thus increasing overall agility. Next, a cognitive two-user radio network is depicted and a method to exploit the inherent network asymmetry to improve agility. It is shown that our cooperation program improves the efficiency of cognitive users by 35%. The researchers then extend the cooperation scheme to two user-per-carrier multi-corporate networks and calculate the gain in asymptotic agility.

In the paper, the QoE-centric adaptive multipath routing tensor model aimed at provisioning the R-factor in software-defined networks has been presented. The flow-based routing model that is the base of the proposed approach takes into account possible packet losses caused by congestion of network elements and includes the conditions for realizing a multipath routing strategy, flow conservation, and link overload prevention. A tensor network description has been applied in order to construct the analytical form of conditions for ensuring the Quality of Experience in terms of the R-factor, as well as the expressions for calculating the average end-to-end delay and the probability of packet loss. Finally, the technological problem of adaptive routing has been reduced to solving the optimization problem of nonlinear programming that made it possible to ensure the adaptability feature of routing solutions when an increase in QoE requirements caused an increase in network resources needed. Using the proposed model is characterized by the load balancing within the multipath obtained for the network. As a result, a numerical study on a network fragment has been demonstrated, which is confirmed the proposed model adequacy and effectiveness in terms of load balancing in a case of increasing the network load.