Academic literature on the topic 'Coded Slotted Aloha (CSA)'

In this paper, we study via simulation the performance of irregular repetition slotted ALOHA under multi-packet detection and different patterns of the load process. On the one hand, we model the arrival process with a version of the M/G/∞ process able to exhibit a correlation structure decaying slowly in time. Given the independence among frames in frame-synchronous coded-slotted ALOHA (CSA), this variation should only take effect on frame-asynchronous CSA. On the other hand, we vary the marginal distribution of the arrival process using discrete versions of the Lognormal and Pareto distributions, with the objective of investigating the influence of the right tail. In this case, both techniques should be affected by the change, albeit to a different degree. Our results confirm these hypotheses and show that these factors must be taken into account when designing and analyzing these systems. In frameless operations, both the shape of the packet arrivals tail distribution and the existence of short-range and long-range correlations strongly impact the packet loss ratio and the average delay. Nevertheless, these effects emerge only weakly in the case of frame-aligned operations, because this enforces the system to introduce a delay in the newly arrived packets (until the beginning of the next frame), and implies that the backlog of accumulated packets is the key quantity for calculating the performance.

ABSTRAKPenggunaan Non-Orthogonal Multiple Access (NOMA) pada sistem komunikasi dapat memberi kebebasan bagi user untuk mengirimkan informasi secara bersamaan tanpa harus memperebutkan timeslot ataupun frekuensi. Coded Random Access (CRA) adalah salah satu bagian dari Coded Comain-NOMA (CDNOMA) yang menggunakan kode tanpa ortogonal untuk komunikasi uplink. Terinspirasi dari Additive Links On Line Hawaii Area (ALOHA), kami menggunakan metode Irregular Repetition Slotted ALOHA (IRSA) dengan tiga jumlah slot node dan sembilan degree distribution pada model kanal Line Of Sight (LOS) dan Non-LOS (NLOS). Kami menggunakan metrik pengukuran berupa throughput dan Packet Loss Ratio (PLR) untuk memperoleh hasil simulasi. Dari simulasi yang ekstensif, kami membuktikan bahwa IRSA stabil pada jumlah slot node yaitu 75, 150 dan 300 yang memperoleh throughput di sekitar 0.75 paket/slot.Kata kunci: Coded Random Access, Non-Orthogonal Multiple Access, Slotted ALOHA, Successive Interference Cancellation ABSTRACTThe use of Non-Orthogonal Multiple Access (NOMA) in communication systems can provide users the freedom to transmit information simultaneously without having to fight over timeslots or frequencies. Coded Random Access (CRA) is a part of Coded Domain-NOMA (CD-NOMA) that uses orthogonal code for uplink communication. Inspired by the Additive Links On Line Hawaii Area (ALOHA), we use the Irregular Repetition Slotted ALOHA (IRSA) method with three number of node slots and nine degree distributions on the Line Of Sight (LOS) and Non-LOS (NLOS) channel models. We use measurements in the form of throughput and Packet Loss Ratio (PLR) to obtain simulation results. From extensive simulations, we prove that IRSA is stable on a wide number of node slots of 75, 150 and 300 that acquire throughput in about 0.75 packets/slot.Keywords: Coded Random Access, Non-Orthogonal Multiple Access, Slotted ALOHA, Successive Interference Cancellation

L'origine concernant l'idée d'ajouter de l'intelligence aux objets de base et de les faire communiquer n'est pas connue précisément. Mais ces derniers temps, l'émergence d'Internet en tant que réseau de communication global a aussi motivé l'utilisation de son architecture et de ses protocoles pour connecter des objets. C'est par exemple le cas célèbre du distributeur automatique de sodas connecté à l'ARPANET dans les années 1980. Au cours des deux dernières décennies, de nombreuses améliorations technologiques ont été développées pour rendre possible l'Internet des objets (IoT). Un scénario d'un réseau IoT typique consiste à connecter des dispositifs embarqués composés de capteurs environnementaux, de microcontrôleurs et de matériel de communication à un nœud de collecte central. L'ensemble des données recueillies par ces nœuds permettra d'analyser et de comprendre précisément les phénomènes et comportements se produisant dans cet environnement. Les applications des technologies IoT sont infinies, car elles sont adaptables à presque tous les systèmes, que l'on doit surveiller et contrôler à distance, pouvant fournir des informations sur son état, son fonctionnement et son environnement. Les villes intelligentes, les soins, l'automatisation industrielle et la technologie portable sont quelques-unes des applications de l'IoT qui promettent de rendre notre vie plus sûre et plus facile. Certains défis en matière de recherche et de technologie doivent être relevés pour la mise en œuvre et la large dissémination des applications de l'IoT comme le déploiement, la mise en réseau, la sécurité, la résilience et le contrôle de l'alimentation des équipements. Cette demande massive de connexion dans les réseaux IoT introduit de nouveaux défis en termes de connectivité, de fiabilité et de technologie. Au niveau de la radio, les réseaux IoT représentent un énorme afflux de divers appareils qui communiquent via le même support radio partagé. Cependant, bon nombre de ces appareils sont difficiles à sécuriser et à manipuler. L'un des principaux défis du déploiement des réseaux IoT est le manque de solutions efficaces qui permettent un nombre massif de connexions tout en répondant en même temps aux exigences de faible latence et de faible coût. De plus, il y a eu récemment une tendance vers des systèmes de communication à longue portée pour l'IoT et aussi pour les réseaux cellulaires. Pour de nombreux cas d'utilisation, tels que les communications massives de type machine (mMTC), les performances peuvent être améliorées en s'éloignant du modèle classique d'établissement de connexion et en adoptant des méthodes d'accès aléatoire sans attribution prédéterminée. Associé à des techniques de couche physique telles que l'annulation successive des interférences (SIC) ou l'accès multiple non orthogonal (NOMA), les performances de l'accès aléatoire peuvent être améliorées, donnant lieu à de nouvelles conceptions de protocoles d'accès aléatoire. Dans cette thèse, nous nous concentrons sur l'un des candidats modernes pour les protocoles d'accès aléatoire bien adaptés à l'IoT :ALOHA à répétition irrégulière (IRSA). Comme des solutions sont nécessaires pour surmonter les défis de l'IoT, nous étudions le schéma d'accès aléatoire IRSA sous de nouveaux points de vue et nous commençons par une analyse des performances des différentes variantes grâce à l'outil de l'évolution de la densité du débit. Précisément, nous commençons par revisiter le scénario du protocole IRSA avec la capacité de réception de paquets multiples (MPR) au niveau du récepteur. Ensuite, nous étudions IRSA dans différents scénarios où des hypothèses plus réalistes sont considérées comme : IRSA avec plusieurs puissances de transmission, avec effet de capture et avec des erreurs de décodage. Dans la deuxième partie de la thèse, nous nous concentrons sur l'apprentissage et l'ajustement dynamique des paramètres du protocole IRSA. Dans un premier temps, nous analysons les performances [...]
The origin of the idea of adding intelligence to basic objects and making them communicate has been lost to history. But in recent times, the emergence of the Internet as a global communication network has also motived the use of its architecture and protocols to connect objects (such as the soda vending machine famously connected to the ARPANET in the 1980s). In the past two decades, many technological enhancements have been developed to enable the ``Internet of Things'' (IoT). A scenario of a typical IoT network is to connect embedded devices composed of environmental sensors, microcontrollers, and communication hardware, to a central collection node. The set of data gathered by these nodes will increasingly help in analyzing and precisely understanding the phenomenons and behaviors occurring in this environment. The applications of IoT technologies are endless because they are adaptable to almost any system that can provide information about its status, operation, and the environment and that one needs to monitor and control at a distance. Smart cities, healthcare, industrial automation, and wearable technology are some IoT applications that promise to make our life safer and easier. Some research and technology challenges need to be addressed for the implementation and full popularization of IoT applications including deployment, networking, security, resilience, and power control. This massive demand for connection in IoT networks will introduce new challenges in terms of connectivity, reliability, and technology. At the radio network level, IoT networks represent a huge inflow of various devices that communicate through the same shared radio medium. However, many of these devices are difficult to secure and handle. One major challenge to deploying IoT networks is the lack of efficient solutions that allow for a massive number of connections while meeting the low-latency and low-cost demands at the same time. In addition, recently, there has been a trend towards long-range communications systems for the IoT, including cellular networks. For many use cases, such as massive machine-type communications (mMTC), performance can be gained by moving away from the classical model of connection establishment and adopting grant-free, random access methods. Associated with physical layer techniques such as Successive Interference Cancellation (SIC), or Non-Orthogonal Multiple Access (NOMA), the performance of random access can be dramatically improved, giving rise to novel random access protocol designs. In this thesis, we focus on one of the modern candidates for random access protocols ``well-fitted'' to the IoT: Irregular Repetition Slotted ALOHA (IRSA). As solutions are needed to overcome the challenges of IoT, we study the IRSA random access scheme from new points of view and we start with an analysis of the performance of different variations through the density evolution tool. Precisely, we start by revisiting the scenario of the IRSA protocol in the case of Multiple Packet Reception (MPR) capability at the receiver. Then, we study IRSA in different scenarios where more realistic assumptions are considered, such as IRSA with multiple transmissions powers, with capture effect, and with decoding errors. In the second part of the thesis, we concentrate on learning and dynamically adjusting IRSA protocol parameters. First, we analyze the protocol performance in a centralized approach through a variant of Reinforcement Learning and in a distributed approach through Game Theory. We also optimize short frame length IRSA through a Deep Reinforcement Learning approach. Finally, we introduce a sensing capability to IRSA, in line with carrier sense principles, and we tentatively explore how one can learn part of sensing protocols with the help of Deep Learning tools

Random access (RA) protocols are normally used in a satellite networks for initial terminal access and are particularly effective since no coordination is required. On the other hand, contention resolution diversity slotted Aloha (CRDSA), irregular repetition slotted Aloha (IRSA) and coded slotted Aloha (CSA) has shown to be more efficient than classic RA schemes as slotted Aloha, and can be exploited also when short packets transmissions are done over a shared medium. In particular, they relies on burst repetition and on successive interference cancellation (SIC) applied at the receiver. The SIC process can be well described using a bipartite graph representation and exploiting tools used for analyze iterative decoding. The scope of my Master Thesis has been to described the performance of such RA protocols when the Rayleigh fading is taken into account. In this context, each user has the ability to correctly decode a packet also in presence of collision and when SIC is considered this may result in multi-packet reception. Analysis of the SIC procedure under Rayleigh fading has been analytically derived for the asymptotic case (infinite frame length), helping the analysis of both throughput and packet loss rates. An upper bound of the achievable performance has been analytically obtained. It can be show that in particular channel conditions the throughput of the system can be greater than one packets per slot which is the theoretical limit of the Collision Channel case.