Non-orthogonal transmission techniques for multibeam satellite systems

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Non-orthogonal transmission is a promising technology enabler to meet the requirements of 5G communication systems. Seminal papers demonstrated that non-orthogonal multiplexing techniques outperform orthogonal schemes in terms of capacity, latency, and user fairness. Since it is envisioned that satellites will be an integral component of the 5G infrastructure, it is worth studying how satellite communication systems can benefit from the application of non-orthogonal transmission schemes as well. Contrary to common perception, current communications through a satellite present a different architecture and face different impairments than those in the wireless terrestrial links. In particular, this work aims to describe different non-orthogonal schemes that are suitable for the forward link (i.e., satellite to user). In contrast with the return link of the satellite (i.e., user to satellite), where the use of non-orthogonal transmission schemes has been widely studied, less effort has been devoted to the forward link. In light of this, this article provides an overview and a novel taxonomy that is based on the forward link of different non-orthogonal multibeam transmission schemes. Finally, guidelines that open new avenues for research in this topic are provided.Peer ReviewedPostprint (author's final draft

Power and Channel Allocation for Non-orthogonal Multiple Access in 5G Systems: Tractability and Computation

Network capacity calls for significant increase for 5G cellular systems. A promising multi-user access scheme, non-orthogonal multiple access (NOMA) with successive interference cancellation (SIC), is currently under consideration. In NOMA, spectrum efficiency is improved by allowing more than one user to simultaneously access the same frequency-time resource and separating multi-user signals by SIC at the receiver. These render resource allocation and optimization in NOMA different from orthogonal multiple access in 4G. In this paper, we provide theoretical insights and algorithmic solutions to jointly optimize power and channel allocation in NOMA. For utility maximization, we mathematically formulate NOMA resource allocation problems. We characterize and analyze the problems' tractability under a range of constraints and utility functions. For tractable cases, we provide polynomial-time solutions for global optimality. For intractable cases, we prove the NP-hardness and propose an algorithmic framework combining Lagrangian duality and dynamic programming (LDDP) to deliver near-optimal solutions. To gauge the performance of the obtained solutions, we also provide optimality bounds on the global optimum. Numerical results demonstrate that the proposed algorithmic solution can significantly improve the system performance in both throughput and fairness over orthogonal multiple access as well as over a previous NOMA resource allocation scheme.Comment: IEEE Transactions on Wireless Communications, revisio

Cancelación sucesiva de interferencias en redes celulares de múltiples transmisores y múltiples receptores

La cancelación sucesiva de interferencias (SIC) Cooperativa es un esquema basado en principios de cooperación de red y que aprovecha la capacidad de los receptores avanzados para realizar SIC. La técnica ha venido abriéndose campo en las investigaciones frente a las nuevas generaciones de redes celulares. Se ha mostrado que SIC Cooperativa puede mejorar la capacidad de un canal en ciertas condiciones para un canal de acceso múltiple. En este trabajo se describen y plantean las condiciones necesarias para el uso de SIC Cooperativa en una red celular, y se implementa un simulador capaz de demostrar su funcionamiento y caracterizar el desempeño del sistema.Cooperative Successive Interference Cancellation (SIC) is a technique based on network cooperation that takes advantage of the capability of advanced receptors to suppress interference. This technique has been receiving attention in research for the next generation of cellular networks. It has been shown that Cooperative SIC can improve the channel capacity for a multiple access channel under certain conditions. In this work, the required conditions for the use of Cooperative SIC on a cellular network are described, a simulator that can demonstrate the technique and characterize its performance is also implemented.Ingeniero (a) ElectrónicoPregrad