Adaptive subframe allocation for next generation multimedia delivery over hybrid LTE unicast broadcast

The continued global roll-out of long term evolution (LTE) networks is providing mobile users with perpetually increasing ubiquitous access to a rich selection of high quality multimedia. Interactive viewing experiences including 3-D or free-viewpoint video require the synchronous delivery of multiple video streams. This paper presents a novel hybrid unicast broadcast synchronisation (HUBS) framework to synchronously deliver multi-stream content. Previous techniques on hybrid LTE implementations include staggered modulation and coding scheme grouping, adaptive modulation coding or implementing error recover techniques; the work presented here instead focuses on dynamic allocation of resources between unicast and broadcast, improving stream synchronisation as well as overall cell resource usage. Furthermore, the HUBS framework has been developed to work within the limitations imposed by the LTE specification. Performance evaluation of the framework is performed through the simulation of probable future scenarios, where a popular live event is broadcast with stereo 3-D or multi-angle companion views interactively offered to capable users. The proposed framework forms a ``HUBS group'' that monitors the radio bearer queues to establish a time lead or lag between broadcast and unicast streams. Since unicast and broadcast share the same radio resources, the number of subframes allocated to the broadcast transmission are then dynamically increased or decreased to minimise the average lead/lag time offset between the streams. Dynamic allocation showed improvements for all services across the cell, whilst keeping streams synchronised despite increased user loading

Coordinated Multicast/Unicast Transmission on 5G: A Novel Approach for Linear Broadcasting

Linear broadcasting services, with a scheduled programming, constitute a paramount tel-ecommunication service for today’s society. Although the existing technology is mature, current linear broadcast systems have serious limitations when providing service to moving users or users placed in areas with complex orography and poor signal quality. To over-come these limitations, 3GPP 5G standard has included a work item to support 5G mul-ticast/broadcast services for future Release 17. This paper investigates the integration of point-to-point (unicast) communication with cellular multicast/broadcast on 5G technology to extend the current support of linear broadcasting services. This integration relies on the use mobile edge computing (MEC) at the 5G base station (gNB) to host a dynamic adap-tive streaming over HTTP (DASH) server that is coordinated with the multicast transmis-sion to complement the broadcast service. This approach join the reliability of point-to-point communications, with dedicated resources for each user, with the spectrum efficiency of multi-cast communications, where a set of users share common resources. The coopera-tion between those unicast and multicast schemes allows those users whose coverage is not good enough, to complete the linear broadcast flow through the point-to-point transmission via MEC. The benefits of such approach have been assessed with simulations in a realistic scenario that considers a vehicle moving across a sparsely populated region in southern Spain. Results reveals that throughput and bitrate playback (reproduction rate) are greatly improved when unicast/multicast integration is enabled since the number of stalling events is reduced significantly.This work has been partially supported by Radio Televisión Española through Impulsa Visión RTVE grant and by the Universidad de Málaga. We are grateful to Pere Vila, Esteban Mayoral Campos, Adolfo Muñoz Berrón and Miguel Ángel Bona San Vicente for their support and collaboration during the development of the project. Funding for open access charge: Universidad de Málaga / CBU

Radio resource allocation algorithms for multicast OFDM systems

Mención Internacional en el título de doctorVideo services have become highly demanded in mobile networks leading to an unprecedented traffic growth. It is expected that traffic from wireless and mobile devices will account for nearly 70 percent of total IP traffic by the year 2020, and the video services will account for nearly 75 percent of mobile data traffic by 2022. Multicast transmission is one of the key enablers towards a more spectral and energy efficient distribution of multimedia content in current and envisaged mobile networks. It is worth noting that multicast is a mechanism that efficiently delivers the same content to many users, not only focusing on video broadcasting, but also distributing many other media, such as software updates, weather forecast or breaking news. Although multicast services are available in Long Term Evolution (LTE) and LTE-Advanced (LTE-A) networks, new improvements are needed in some areas to handle the demands expected in the near future. Resource allocation techniques for multicast services are one of the main challenging issues, since it is required the development of novel schemes to meet the demands of their evolution towards the next generation. Most multicast techniques adopt rather conservative strategies that select a very robust modulation and coding scheme (MCS), whose characteristics are determined by the propagation conditions experienced by the worst user in the group in order to ensure that all users in a multicast group are able to correctly decode the received data. Obviously, this robustness comes at the prize of a low spectral efficiency. This thesis presents an exhaustive study of broadcast/multicast technology for current mobile networks, especially focusing on the scheduling and resource allocation (SRA) strategies to maximize the potential benefits that multicast transmissions imply on the spectral efficiency. Based on that issue, some contributions have been made to the state of the art in the radio resource management (RRM) for current and beyond mobile multicast services. • In the frame of LTE/LTE-A, the evolved multimedia broadcast and multicast service (eMBMS) shares the physical layer resources with the unicast transmission mode (at least up to Release 12). Consequently, the time allocation to multicast transmission is limited to a maximum of a 60 percent, and the remaining subframes (at least 40 percent) are reserved for unicast transmissions. With the aim of achieving the maximum aggregated data rate (ADR) among the multicast users, we have implemented several innovative SRA schemes that combine the allocation of multicast and unicast resources in the LTE/LTE-A frame, guaranteeing the prescribed quality of service (QoS) requirements for every user. • In the specific context of wideband communication systems, the selection of the multicast MCS has often relied on the use of wideband channel quality indicators (CQIs), providing rather imprecise information regarding the potential capacity of the multicast channel. Only recently has the per-subband CQI been used to improve the spectral efficiency of the system without compromising the link robustness. We have proposed novel subband CQI-based multicast SRA strategies that, relying on the selection of more spectrally efficient transmission modes, lead to increased data rates while still being able to fulfill prescribed QoS metrics. • Mobile broadcast/multicast video services require effective and low complexity SRA strategies. We have proposed an SRA strategy based on multicast subgrouping and the scalable video coding (SVC) technique for multicast video delivery. This scheme focuses on reducing the search space of solutions and optimizes the ADR. The results in terms of ADR, spectral efficiency, and fairness among multicast users, along with the low complexity of the algorithm, show that this new scheme is adequate for real systems. These contributions are intended to serve as a reference that motivate ongoing and future investigation in the challenging field of RRM for broadcast/ multicast services in next generation mobile networks.La demanda de servicios de vídeo en las redes móviles ha sufrido un incremento exponencial en los últimos años, lo que a su vez ha desembocado en un aumento sin precedentes del tráfico de datos. Se espera que antes del año 2020, el trafico debido a dispositivos móviles alcance cerca del 70 por ciento del tráfico IP total, mientras que se prevé que los servicios de vídeo sean prácticamente el 75 por ciento del tráfico de datos en las redes móviles hacia el 2022. Las transmisiones multicast son una de las tecnologías clave para conseguir una distribución más eficiente, tanto espectral como energéticamente, del contenido multimedia en las redes móviles actuales y futuras. Merece la pena reseñar que el multicast es un mecanismo de entrega del mismo contenido a muchos usuarios, que no se enfoca exclusivamente en la distribución de vídeo, sino que también permite la distribución de otros muchos contenidos, como actualizaciones software, información meteorológica o noticias de última hora. A pesar de que los servicios multicast ya se encuentran disponibles en las redes Long Term Evolution (LTE) y LTE-Advanced (LTE-A), la mejora en algunos ámbitos resulta necesaria para manejar las demandas que se prevén a corto plazo. Las técnicas de asignación de recursos para los servicios multicast suponen uno de los mayores desafíos, ya que es necesario el desarrollo de nuevos esquemas que nos permitan acometer las exigencias que supone su evolución hacia la próxima generación. La mayor parte de las técnicas multicast adoptan estrategias conservadoras, seleccionando esquemas de modulación y codificación (MCS) impuestos por las condiciones de propagación que experimenta el usuario del grupo con peor canal, para así asegurar que todos los usuarios pertenecientes al grupo multicast sean capaces de decodificar correctamente los datos recibidos. Como resulta obvio, la utilización de esquemas tan robustos conlleva el precio de sufrir una baja eficiencia espectral. Esta tesis presenta un exhaustivo estudio de la tecnología broadcast/ multicast para las redes móviles actuales, que se centra especialmente en las estrategias de asignación de recursos (SRA), cuyo objetivo es maximizar los beneficios que la utilización de transmisiones multicast potencialmente implica en términos de eficiencia espectral. A partir de dicho estudio, hemos realizado varias contribuciones al estado del arte en el ámbito de la gestión de recursos radio (RRM) para los servicios multicast, aplicables en las redes móviles actuales y futuras. • En el marco de LTE/LTE-A, el eMBMS comparte los recursos de la capa física con las transmisiones unicast (al menos hasta la revisión 12). Por lo tanto, la disponibilidad temporal de las transmisiones multicast está limitada a un máximo del 60 por ciento, reservándose las subtramas restantes (al menos el 40 por ciento) para las transmisiones unicast. Con el objetivo de alcanzar la máxima tasa total de datos (ADR) entre los usuarios multicast, hemos implementado varios esquemas innovadores de SRA que combinan la asignación de los recursos multicast y unicast de la trama LTE/LTE-A, garantizando los requisitos de QoS a cada usuario. • En los sistemas de comunicaciones de banda ancha, la selección del MCS para transmisiones multicast se basa habitualmente en la utilización de CQIs de banda ancha, lo que proporciona información bastante imprecisa acerca de la capacidad potencial del canal multicast. Recientemente se ha empezado a utilizar el CQI por subbanda para mejorar la eficiencia espectral del sistema sin comprometer la robustez de los enlaces. Hemos propuesto nuevas estrategias para SRA multicast basadas en el CQI por subbanda que, basándose en la selección de los modos de transmisión con mayor eficiencia espectral, conducen a mejores tasas de datos, a la vez que permiten cumplir los requisitos de QoS. • Los servicios móviles de vídeo broadcast/multicast precisan estrategias eficientes de SRA con baja complejidad. Hemos propuesto una estrategia de SRA basada en subgrupos multicast y la técnica de codificación de vídeo escalable (SVC) para la difusión de vídeo multicast, la cual se centra en reducir el espacio de búsqueda de soluciones y optimizar el ADR. Los resultados obtenidos en términos de ADR, eficiencia espectral y equidad entre los usuarios multicast, junto con la baja complejidad del algoritmo, ponen de manifiesto que el esquema propuesto es adecuado para su implantación en sistemas reales. Estas contribuciones pretenden servir de referencia que motive la investigación actual y futura en el interesante ámbito de RRM para los servicios broadcast/multicast en las redes móviles de próxima generación.Programa Oficial de Doctorado en Multimedia y ComunicacionesPresidente: Atilio Manuel Da Silva Gameiro.- Secretario: Víctor Pedro Gil Jiménez.- Vocal: María de Diego Antó

A fast and reliable broadcast service for LTE-advanced exploiting multihop device-to-device transmissions

Several applications, from the Internet of Things for smart cities to those for vehicular networks, need fast and reliable proximity-based broadcast communications, i.e., the ability to reach all peers in a geographical neighborhood around the originator of a message, as well as ubiquitous connectivity. In this paper, we point out the inherent limitations of the LTE (Long-Term Evolution) cellular network, which make it difficult, if possible at all, to engineer such a service using traditional infrastructure-based communications. We argue, instead, that network-controlled device-to-device (D2D) communications, relayed in a multihop fashion, can efficiently support this service. To substantiate the above claim, we design a proximity-based broadcast service which exploits multihop D2D. We discuss the relevant issues both at the UE (User Equipment), which has to run applications, and within the network (i.e., at the eNodeBs), where suitable resource allocation schemes have to be enforced. We evaluate the performance of a multihop D2D broadcasting using system-level simulations, and demonstrate that it is fast, reliable and economical from a resource consumption standpoint

Towards an LTE hybrid unicast broadcast content delivery framework

The era of ubiquitous access to a rich selection of interactive and high quality multimedia has begun; with it, significant challenges in data demand have been placed on mobile network technologies. Content creators and broadcasters alike have embraced the additional capabilities offered by network delivery; diversifying content offerings and providing viewers with far greater choice. Mobile broadcast services introduced as part of the Long Term Evolution (LTE) standard, that are to be further enhanced with the release of 5G, do aid in spectrally efficient delivery of popular live multimedia to many mobile devices, but, ultimately rely on all users expressing interest in the same single stream. The research presented herein explores the development of a standards aligned, multi-stream aware framework; allowing mobile network operators the efficiency gains of broadcast whilst continuing to offer personalised experiences to subscribers. An open source, system level simulation platform is extended to support broadcast, characterised and validated. This is followed by the implementation of a Hybrid Unicast Broadcast Synchronisation (HUBS) framework able to dynamically vary broadcast resource allocation. The HUBS framework is then further expanded to make use of scalable video content

Point-to-Multipoint Services on Fifth-Generation Mobile Networks

[ES] Esta disertación cubre el estado del arte en LTE eMBMS Release 14, también conocido como Enhanced Television Services (ENTV). ENTV trajo un conjunto de mejoras, tanto a nivel radio como a nivel de núcleo, que transformó a eMBMS en un estándar de televisión terrestre completo. La última versión de esta tecnología se denomina LTE-based 5G Broadcast; pero no usa New Radio ni el núcleo 5G. Para proveer una solución nativa 5G de servicios punto-a-multipunto, hubo investigación en entornos acad\'emicos y colaboraciones público-privada. La iniciativa más notable en este aspecto fue el proyecto del Horizon 2020 5G-Xcast, que transcurrió de 2017 a 2019. 5G-Xcast produjo varias soluciones a nivel de arquitectura, desde la perspectiva de provisión de contenidos, nuevas funciones de red interoperables con el núcleo 5G, hasta modificaciones a la interfaz aire basada en New Radio. Los hallazgos del proyecto están descritos en esta tesis. La tesis incluye dos ejemplos de eMBMS aplicados a verticales diferentes, una para el uso de eMBMS en entornos industriales, y otra presentando eMBMS como un sistema SAP. Incluir servicios punto-a-multipunto como un modo adicional celular trae algunos desafíos, como ya mostró la estandarización de eMBMS: las redes de radiodifusión terrestre y las redes celulares son muy distintas entre ellas. Encontrar una forma de onda viable para ambas infraestructuras es complejo. Esta tesis ofrece un punto de vista distinto al problema: un escenario de colaboración entre cadenas televisivas y operadores móviles, donde la infraestructura de radiodifusión y móvil son compartidas. Este concepto se ha definido como Convergence of Terrestrial and Mobile Networks. Las tecnologías elegidas para converger son ATSC 3.0 y 5G, usando el Advanced Traffic Steering, Switching and Splitting (ATSSS). ATSSS está compuesto de una serie de procedimientos, interfaces, funciones de red, para permitir el uso compartido de un acceso 3GPP con uno non-3GPP, como Wi-Fi. Sin embargo, el uso de ATSSS para juntar radiodifusión y celular no es trivial, ya que ATSSS no fue dise\~{n}ado para enlaces radio unidireccionales como ATSC 3.0. Estas limitaciones son descritas en detalle, y una propuesta para solventarlas tambi\'en está incluida. La solución se basa en Quick UDP Internet Connections (QUIC), y se usa como ejemplo para la provisión de Convergent Services (File Repair y Video Offloading). La tesis concluye con una descripción de Release 17 5MBS, con los nuevos conceptos introducidos. 5MBS es capaz de cambiar entre unicast, multicast y broadcast; dependiendo del servicio, la ubicación geográfica de los usuarios, y las capacidades de la infraestructura móvil involucradas. Para evaluar 5MBS, se ha realizado un estudio de prestaciones, basado en comunicaciones multicast dentro del núcleo de red 5G. Este prototipo 5MBS forma parte del laboratorio VLC Campus 5G, y utiliza el software comercial Open5GCore como base del desarrollo. El modelo de sistema para la experimentación esta formado por un servidor de vídeo, que se conecta al Open5GCore y a las funciones de red mejoradas con funcionalidades 5MBS. Estas funciones de red envían el contenido mediante punto-a-multipunto a un entorno radio y terminales simulados. Los resultados obtenidos resaltan el objetivo principal de la tesis: las comunicaciones punto-a-multipunto son una solución escalable para el envío de contenido multimedia en directo.[CA] Aquesta dissertació cobreix capdavanter en LTE eMBMS Release 14, també conegut com Enhanced Television Services (ENTV). ENTV va portar un conjunt de millores, tant a nivell de ràdio com a nivell de nucli, que va transformar el eMBMS en un estàndard de televisió terrestre complet. La última versió d'aquesta tecnologia es denomina LTE-based 5G Broadcast; però no fa servir New Ràdio ni el nucli 5G. Per a proveir una solució nativa 5G de serveis punt-a-multipunt, va haver-hi investigació en entorns acadèmics i col·laboracions pública i privada. La iniciativa més notable en aquest aspecte va ser el projecte del Horizon 2020 5G-Xcast, que va transcórrer del 2017 a 2019. 5G-Xcast va produir diverses solucions a nivell d'arquitectura, des de la perspectiva de provisió de continguts, noves funcions de xarxa interoperables amb el nucli 5G, fins a modificacions a la interfície aire basada en New Radio. Les troballes del projecte estan descrits en aquesta tesi. La tesi inclou dos exemples de eMBMS aplicats a verticals diferents, una per a l'ús de eMBMS en entorns industrials, i una altra presentant eMBMS com un sistema SAP. Incloure serveis punt-a-multipunt com una manera addicional cel·lular duu alguns desafiaments, com ja va mostrar l'estandardització de eMBMS: les xarxes de radiodifusió terrestre i les xarxes cel·lulars són molt diferents entre elles. Trobar una forma d'ona viable per a totes dues infraestructures és complex. Aquesta tesi ofereix un punt de vista diferent al problema: un escenari de col·laboració entre cadenes televisives i operadors mòbils, on la infraestructura de radiodifusió i mòbil són compartides. Aquest concepte s'ha definit com Convergence of Terrestrial and Mobile Networks. Les tecnologies triades per a convergir són ATSC 3.0 i 5G, usant el Advanced Traffic Steering, Switching and Splitting (ATSSS). ATSSS està compost d'una sèrie de procediments, interfícies, funcions de xarxa, per a permetre l'ús compartit d'un accés 3GPP amb un non-3GPP, com a Wi-Fi. No obstant això, l'ús de ATSSS per a adjuntar radiodifusió i cel·lular no és trivial, ja que ATSSS no va ser dissenyada per a per a enllaços ràdio unidireccionals com ATSC 3.0. Aquestes limitacions són descrites detalladament, i una proposta per a solucionar-les també està inclosa. La solució es basa en Quick UDP Internet Connections (QUIC), i s'usa com a exemple per a la provisió de Convergent Services (File Repair i Vídeo Offloading). La tesi conclou amb una descripció de Release 17 5MBS, amb els nous conceptes introduïts. 5MBS és capaç de canviar entre unicast, multicast i broadcast; depenent del servei, la ubicació geogràfica dels usuaris, i les capacitats de la infraestructura mòbil involucrades. Per a avaluar 5MBS, s'ha realitzat un estudi de prestacions, basat en comunicacions multicast dins del nucli de xarxa 5G. Aquest prototip 5MBS forma part del laboratori VLC Campus 5G, i utilitza el programari comercial Open5GCore com a base del desenvolupament. El model de sistema per a l'experimentació està format per un servidor de vídeo, que es connecta al Open5GCore i a les funcions de xarxa millorades amb funcionalitats 5MBS. Aquestes funcions de xarxa envien el contingut mitjançant punt-a-multipunt a un entorn ràdio i terminals simulats. Els resultats obtinguts ressalten l'objectiu principal de la tesi: les comunicacions punt-a-multipunt són una solució escalable per a l'enviament de contingut multimèdia en directe.[EN] This dissertation covers the state-of-the-art in LTE eMBMS Release 14, also known as Enhanced Television Services (ENTV). ENTV provided a suite of radio and core enhancements that made eMBMS into a viable terrestrial broadcast standard. The latest iteration of this technology is known as LTE-based 5G Broadcast; even though it is not New Radio or 5G Core based. To bridge this gap, research efforts by academia, public and private enterprises evaluated how to provide a 5G-based solution for point-to-multipoint services. The most notable effort in this regard is the Horizon 2020 project 5G-Xcast, which ran from 2017 to 2019. 5G-Xcast provided several architectural solutions, from the content delivery perspective down to air interface specifics; providing new waveforms based on New Radio and Network Functions interoperable with a Release 15 5G Core. The findings are summarized in this thesis. Two examples of eMBMS applied to different verticals are included in the thesis, one for the use of eMBMS in industrial environments, and the other using eMBMS as a PWS technology. Providing point-to-multipoint services as another cellular service poses some problems, as the standardization process of eMBMS showed: the broadcast infrastructure is different than the cellular one. Having a waveform that is suited for both scenarios is a difficult endeavour. The thesis provides a new perspective into this problem: Having existing Terrestrial Broadcast standards and infrastructure be the point-to-multipoint solution of 5G, where mobile operators and broadcasters collaborate together. This is defined in the dissertation as Convergence of Terrestrial and Mobile Networks. The technologies chosen to be converged together were ATSC 3.0 and 5G; using the existing Release 16 framework known as Advanced Traffic Steering, Switching and Splitting (ATSSS). ATSSS is a series of procedures, interfaces, new Network Functions, to allow the joint use of a 3GPP Access Network alongside a non-3GPP one, like Wi-Fi. However, the use of ATSSS for cellular plus broadcast brings challenges, as the ATSSS technology was not designed to be used with a unidirectional access network like ATSC 3.0. These limitations are described in detail, and an architectural proposal that overcomes the limitations is proposed. This solution is based on Quick UDP Internet Connections (QUIC), and how to provide Convergent Services (i.e File Repair and Video Offloading) is shown. The thesis concludes with a description of Release 17 5MBS, including the new concepts introduced. 5MBS features the capacity of switching between unicast, multicast and broadcast; depending on the service addressed, the geographical location of the users, and the capability of the RAN infrastructure targeted. In order to evaluate 5MBS, a performance study of the use of multicast inside the 5G Core has been carried out. The 5MBS prototype was developed as part of the VLC Campus 5G laboratory, using the commercial software Open5GCore which provides the libraries and Network Functions to deploy your own 5G Private Network in testing environments. The system model of the experiment is formed by a video server, connected to the Open5GCore and the 5MBS enhanced functions; which will deliver the content to an emulated RAN environment hosting virtual gNBs and devices. The results obtained reinforce the objective of the thesis, positioning point-to-multipoint as a scalable way to deliver live content.Research projects: 5G-Xcast: Broadcast and Multicast Communication Enablers for the Fifth-Generation of Wireless Systems (H2020 No 761498); 5G-TOURS: SmarT mObility, media and e-health for toURists and citizenS (H2020 No 856950); FUDGE-5G: FUlly DisinteGrated private nEtworks for 5G verticals (H2020 No 957242).Barjau Estevan, CS. (2022). Point-to-Multipoint Services on Fifth-Generation Mobile Networks [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/19140

MBMS—IP Multicast/Broadcast in 3G Networks

In this article, the Multimedia Broadcast and Multicast Service (MBMS) as standardized in 3GPP is presented. With MBMS, multicast and broadcast capabilities are introduced into cellular networks. After an introduction into MBMS technology, MBMS radio bearer realizations are presented. Different MBMS bearer services like broadcast mode, enhanced broadcast mode and multicast mode are discussed. Streaming and download services over MBMS are presented and supported media codecs are listed. Service layer components as defined in Open Mobile Alliance (OMA) are introduced. For a Mobile TV use case capacity improvements achieved by MBMS are shown. Finally, evolution of MBMS as part of 3GPP standardization is presented

Towards efficient support for massive Internet of Things over cellular networks

The usage of Internet of Things (IoT) devices over cellular networks is seeing tremendous growth in recent years, and that growth in only expected to increase in the near future. While existing 4G and 5G cellular networks offer several desirable features for this type of applications, their design has historically focused on accommodating traditional mobile devices (e.g. smartphones). As IoT devices have very different characteristics and use cases, they create a range of problems to current networks which often struggle to accommodate them at scale. Although newer cellular network technologies, such as Narrowband-IoT (NB-IoT), were designed to focus on the IoT characteristics, they were extensively based on 4G and 5G networks to preserve interoperability, and decrease their deployment cost. As such, several inefficiencies of 4G/5G were also carried over to the newer technologies. This thesis focuses on identifying the core issues that hinder the large scale deployment of IoT over cellular networks, and proposes novel protocols to largely alleviate them. We find that the most significant challenges arise mainly in three distinct areas: connection establishment, network resource utilisation and device energy efficiency. Specifically, we make the following contributions. First, we focus on the connection establishment process and argue that the current procedures, when used by IoT devices, result in increased numbers of collisions, network outages and a signalling overhead that is disproportionate to the size of the data transmitted, and the connection duration of IoT devices. Therefore, we propose two mechanisms to alleviate these inefficiencies. Our first mechanism, named ASPIS, focuses on both the number of collisions and the signalling overhead simultaneously, and provides enhancements to increase the number of successful IoT connections, without disrupting existing background traffic. Our second mechanism focuses specifically on the collisions at the connection establishment process, and used a novel approach with Reinforcement Learning, to decrease their number and allow a larger number of IoT devices to access the network with fewer attempts. Second, we propose a new multicasting mechanism to reduce network resource utilisation in NB-IoT networks, by delivering common content (e.g. firmware updates) to multiple similar devices simultaneously. Notably, our mechanism is both more efficient during multicast data transmission, but also frees up resources that would otherwise be perpetually reserved for multicast signalling under the existing scheme. Finally, we focus on energy efficiency and propose novel protocols that are designed for the unique usage characteristics of NB-IoT devices, in order to reduce the device power consumption. Towards this end, we perform a detailed energy consumption analysis, which we use as a basis to develop an energy consumption model for realistic energy consumption assessment. We then take the insights from our analysis, and propose optimisations to significantly reduce the energy consumption of IoT devices, and assess their performance