The non-orthogonal multiple access (NOMA) allows one subcarrier to be allocated to more than one user at the same time in an orthogonal frequency division multiplexing (OFDM) system. NOMA is a promising technique to provide high throughput due to frequency reuse within a cell. In this paper, a novel interference cancellation (IC) technique is proposed for asynchronous NOMA systems. The proposed IC technique exploits a triangular pattern to perform the IC from all interfering users for the desired user. The bit error rate (BER) and capacity performance analysis of an uplink NOMA system with the proposed IC technique is presented, along with the comparison to orthogonal frequency division multiple access (OFDMA) systems. The numerical and simulation results show that the NOMA with the proposed asynchronous IC technique outperforms the OFDMA. It is also shown that employing iterative IC provides significant performance gain for NOMA and the number of required iterations depends on the modulation level and the detection method. With hard-decision, two iterations are sufficient, however with soft-decision, two iterations are enough only for low modulation level, and more iterations are desirable for high modulation level.

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SUMMARYA Petri‐net‐based simulation model of a wireless mobile ad hoc network is developed and studied. The model covers all the fundamental aspects of behaviour of such a network and uses a novel scheme of orientation‐dependent (or sector‐dependent) internode communication, with random states of links. The proposed scheme enables representation of reliability aspects of wireless communication, such as fading effects, interferences, presence of obstacles and weather conditions in a general and rather easy way. The simulation model was implemented in terms of a class of extended Petri nets to explicitly represent parallelism of events and processes in the WLAN as a distributed system. In the simulation, the behaviour of four fundamental performance metrics — packet delivery ratio, average number of hops, relative network traffic and end‐to‐end delay — were investigated with varying distance of transmission and different combinations of model parameters. Copyright © 2012 John Wiley & Sons, Ltd.

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This paper proposes two novel packet scheduling schemes, called as throughput enhanced scheduling (TES) and TES plus (TES+), for future ultra-dense networks. These schemes introduce two novel parameters to the scheduling decision making and reformulate the parameters used by the state-of-the-art schemes. The aim is to have a more balanced weight distribution between delay and throughput-related parameters at scheduling decisions. Also include a new telecommunications related parameter into scheduling decision making that has not been studied by popular schedulers. The performance of novel schemes is compared with well-known schemes-proportional fairness (PF), exponential/proportional fairness (EXP/PF), and M-LWDF. For performance evaluation, five performance metrics-average spectral efficiency and delay, quality of service (QoS) violation ratio, jitter, and Jain's fairness index-are investigated. The simulation results show that proposed schemes can outperform all the compared scheduling schemes. KEYWORDS5G networks, EXP/PF, M-LWDF, packet scheduling, real-time traffic, ultra-dense networks Int J Commun Syst. 2020;33:e4229.wileyonlinelibrary.com/journal/dac

The fifth-generation (5G) of cellular technology is currently being deployed over the world. In the next decade of mobile networks, beyond 5G (B5G) cellular networks with the under-development advanced technology enablers are expected to be a fully developed system that could offer tremendous opportunities for both enterprises and society at large. B5G in more ambitious scenarios will be capable to facilitate much-improved performance with the significant upgrade of the key parameters such as massive connectivity, ultra-reliable and low latency (URLL), spectral efficiency (SE) and energy efficiency (EE). Equipping non-orthogonal multiple access (NOMA) with other key drivers will help to explore systems' applicability to cover a wide variety of applications to forge a path for future networks. NOMA empowers the networks with seamless connectivity and can provide a secure transmission strategy for the industrial internet of things (IIoT) anywhere and anytime. Despite being a promising candidate for B5G networks a comprehensive study that covers operating principles, fundamental features and technological feasibility of NOMA at mmWave massive MIMO communications is not available. To address this, a simulation-based comparative study between NOMA and orthogonal multiple access (OMA) techniques for mmWave massive multiple-input and multiple-output (MIMO) communications is presented with performance discussions and identifying technology gaps. Throughout the paper, aspects of operating principles, fundamental features and technological feasibility of NOMA are discussed. Also, it is demonstrated that NOMA not only has good adaptability but also can outperform other OMA techniques for mmWave massive MIMO communications. Some foreseeable challenges and future directions on applying NOMA to B5G networks are also provided.

Wireless networks are today employed as complementary access technology, implemented on the last hop towards the Internet end-user. The shared media that wireless deployments provide and which is relevant to interconnect multiple users has a limited technical design, as only one device can be served per unit of time, design aspect that limits the potential applicability of wireless in dense environments. This paper proposes and evaluates a novel MAC-layer mechanism that extends current wireless networks with the possibility to perform downstream transmission to multiple devices within a single transmission time-frame, resulting in improved fairness for all devices. The mechanism, which is software-defined, is backward-compatible with current wireless standards and does not require any hardware changes. The solution has been validated in a realistic testbed, and the paper provides details concerning the computational aspects of our solution; a description of the implementation; and results extracted under different realistic scenarios in terms of throughput, packet loss, as well as jitter.Index Terms-OFDMA, resource management, user-centric networking, wireless. 1063-6692