Architectures and Key Technical Challenges for 5G Systems Incorporating Satellites

Satellite Communication systems are a promising solution to extend and complement terrestrial networks in unserved or under-served areas. This aspect is reflected by recent commercial and standardisation endeavours. In particular, 3GPP recently initiated a Study Item for New Radio-based, i.e., 5G, Non-Terrestrial Networks aimed at deploying satellite systems either as a stand-alone solution or as an integration to terrestrial networks in mobile broadband and machine-type communication scenarios. However, typical satellite channel impairments, as large path losses, delays, and Doppler shifts, pose severe challenges to the realisation of a satellite-based NR network. In this paper, based on the architecture options currently being discussed in the standardisation fora, we discuss and assess the impact of the satellite channel characteristics on the physical and Medium Access Control layers, both in terms of transmitted waveforms and procedures for enhanced Mobile BroadBand (eMBB) and NarrowBand-Internet of Things (NB-IoT) applications. The proposed analysis shows that the main technical challenges are related to the PHY/MAC procedures, in particular Random Access (RA), Timing Advance (TA), and Hybrid Automatic Repeat reQuest (HARQ) and, depending on the considered service and architecture, different solutions are proposed.Comment: Submitted to Transactions on Vehicular Technologies, April 201

Performance of narrow band internet of things (NBIoT) networks

Narrow Band Internet of Things (NBIoT) is a Low Power Wide Area Network (LPWAN) technology that has been standardised by 3GPP in Release 13 to work in cellular networks [15]. The main characteristics of NBIoT are its extended coverage compared to other cellular technologies such as LTE; its high capacity is due to its narrow channel bandwidth of 180 KHz, which also supports the possibility of these devices having a long battery life of up to 10 years, as well as low device complexity - all of which result in low device costs [2]. NBIoT can be deployed in one of three different options, namely: a) standalone, b) in-band and c) guard band deployment mode. These characteristics of NBIoT makes it very useful in the IoT industry, allowing the technology to be used in a wide range of applications, such as health, smart cities, farming, wireless sensor networks and many more [1] [25]. NBIoT can be used to realise the maximum possible spectral efficiency, thereby increasing the capacity of the network. Penetration of NBIoT in the market has dominated other LPWANs like Sigfox and LoRA, with NBIoT having a technology share of close to 50 percent [31]. This study is aimed at exploring the deployment options of NBIoT and determining how network operators can realise the greatest value for their investment by efficiently utilising their allocated spectrum. The main target is to derive the best parameter combination for deployment of the NBIoT network with acceptable error rates in both the uplink and the downlink. Different characteristics of NBIoT were discussed in this study, and the performance of the various approaches investigated to determine their efficiency in relation to the needs of the IoT industry. The error rates of NBIoT, when used in an existing LTE network, were the main focus of this study. Software simulations were used to compare the different parameter settings to see which options provide the best efficiency and cost trade-offs for structuring an NBIoT network. The results of the tests done in this study showed that the error rates are lower for standalone deployment mode than for in-band mode, which is mainly due to less interference in standalone mode than in in-band mode. The results also show that data transmitted in smaller Transport Block Size (TBS) in the Down Link (DL) has less errors than if it’s transmitted in larger blocks. The results also show that the error rate gets lower as the number of subframe repetition increases in the downlink, which is mainly due to the redundancy in sending the same data multiple times. However in the uplink, the results show that the error rates are comparable when the signal has poor quality

Performance assessment of NB-IoT protocol over satellite channels

Abstract Cellular networks play a very important role in nowadays paradigm which goal is to establish connectivity all around the world. Low power wide area networks (LPWAN) seem to fit well within low-cost devices, which constitute a great part of the electronics market. In this context, the narrowband internet of things (NB-IoT) protocol specified by the 3GPP is consolidating as one of the most adopted technologies in the field of LPWAN, together with LoRaWAN. With the goal of reaching global coverage, the NB-IoT protocol, which was mainly designed for terrestrial cellular networks, is now being extended to be able to work also on satellite networks. The support of satellite access is seen as the enabler of truly massive machine-type communications (mMTC) into areas that cellular connectivity is limited or inexistent (remote areas, air and sea communications). This thesis provides a performance assessment of the NB-IoT protocol under different satellite link conditions and transmission modes. The assessment is conducted using the MATLAB LTE Toolbox.Las redes móviles tienen un papel muy importante en la actualidad, puesto que tienen como objetivo establecer conectividad en todo el mundo. Las redes de bajo consumo y largo alcance (LPWAN) parecen encajar bien en un entorno donde los dispositivos de bajo coste constituyen una gran parte del mercado de la electrónica. En este contexto, el protocolo NB-IoT especificado por el 3GPP se consolida como una de las tecnologías más adoptadas en el contexto de LPWAN, junto con LoRaWAN. Con el objetivo de conseguir una cobertura global, el protocolo NB-IoT, que fue diseñado principalmente para redes de telefonía terrestre, ahora se está ampliando para poder trabajar también en redes de satélite. El acceso por satélite es visto como la puerta hacia las comunicaciones de tipos máquina masiva (mMTC) en áreas donde la conectividad celular es limitada o inexistente (áreas remotas, comunicaciones aéreas y marítimas). Esta tesis proporciona una evaluación del rendimiento del protocolo NB-IoT bajo diferentes condiciones de enlace por satélite y modos de transmisión. La evaluación se realiza utilizando la caja de herramientas MATLAB LTE.Les xarxes mòbils tenen un paper molt important en l'actualitat, ja que tenen com a objectiu establir connectivitat a tot el món. Les xarxes de baix consum i llarg abast (LPWAN) semblen encaixar bé en un entorn on els dispositius de baix cost constitueixen una gran part del mercat de l'electrònica. En aquest context, el protocol NB-IoT especificat pel 3GPP es consolida com una de les tecnologies més adoptades en el context de LPWAN, juntament amb LoRaWAN. Amb l'objectiu d'aconseguir una cobertura global, el protocol NB-IoT, que va ser dissenyat principalment per a xarxes de telefonia terrestre, ara s'està ampliant per poder treballar també en xarxes de satèl·lit. L'accés per satèl·lit és vist com la porta cap a comunicacions de tipus màquina massiva (mMTC) en àrees on la connectivitat cel·lular és limitada o inexistent (àrees remotes, comunicacions aèries i marítimes). Aquesta tesi proporciona una avaluació del rendiment del protocol NB-IoT sota diferents condicions d'enllaç per satèl·lit i modes de transmissió. L'avaluació es realitza utilitzant la caixa d'eines MATLAB LTE

Clock Error Impact on NB-IoT Radio Link Performance

3GPP has recently addressed the improvements in Random Access Network (RAN) and specified some new technologies such as enhanced Machine Type Communication (eMTC) and Narrow Band – Internet of Things (NB-IoT) in its release 13 which is also known as LTE-Advanced Pro. These new technologies are addressed mainly to focus on development and deployment of cellular IoT services. NB-IoT is less complex and easily deployable through software upgradation and is compatible to legacy cellular networks such as GSM and 4G which makes it a suitable candidate for IoT. NB-IoT will greatly support LPWAN, thus, it can be deployed for Smart cities and other fields such as smart electricity, smart agriculture, smart health services and smart homes. The NB-IoT targets for low cost device, low power consumption, relaxed delay sensitivity and easy deployment which will greatly support above mentioned fields. This thesis work studies the clock error impact on the radio link performance for up-link transmission on the NB-IoT testbed based on Cloud-RAN using Software Defined Radios (SDR) on a LTE protocol stack. The external clock error is introduced to the network and performance issues are analyzed in the radio link. The analysis indicates packet drops up to 51% in the radio link through the study of received power, packet loss, retransmissions, BLER and SINR for different MCS index. The major performance issues depicted by the analysis are packet loss up to 51% and retransmission of packets up to 128 times for lower SINR and high clock errors. Also, clock errors produce CFO up to 1.25 ppm which results in bad synchronization between UE and eNodeB

Time- and frequency-asynchronous aloha for ultra narrowband communications

A low-power wide-area network (LPWAN) is a family of wireless access technologies which consume low power and cover wide areas. They are designed to operate in both licensed and unlicensed frequency bands. Among different low-power wide-area network (LPWAN) technolo-gies, long range (LoRa), Sigfox, and Narrowband Internet of Things (NB-IoT) are leading in IoT deployment in large-scale. However, Sigfox and LoRa both have advantages in terms of battery lifetime, production cost and capacity whereas lower latency and better quality of service are of-fered by Narrowband Internet of Things (NB-IoT) operating licensed cellular frequency bands. The two main approaches for reaching wide coverage with low transmission power are (i) spread spectrum, used by LoRa, and (ii) ultra-narrow band (UNB) which is used by Sigfox. This thesis work focuses on the random-access schemes for UNB based IoT networks mainly. Due to issues related to receiver synchronization, two-dimensional time-frequency ran-dom access protocol is a particularly interesting choice for UNB transmission schemes. Howev-er, UNB possess also some major constraints regarding connectivity, throughput, noise cancel-lation and so. This thesis work investigates UNB-based LPWAN uplink scenarios. The throughput perfor-mance of Time Frequency Asynchronous ALOHA (TFAA) is evaluated using MATLAB simula-tions. The main parameters include the interference threshold which depends on the robust-ness of the modulation and coding scheme, propagation exponent, distance range of the IoT devices and system load. Normalized throughput and collision probability are evaluated through simulations for different combinations of these parameters. We demonstrate that, using repeti-tions of the data packets results in a higher normalized throughput. The repetition scheme is designed in such a way that another user's packets may collide only with one of the target packets repetitions. The power levels as well as distances of a user’s all repetitions are consid-ered same. By using repetitions, reducing the distance range, and increasing the interference threshold, the normalized throughput can be maximized

Performance Analysis of IoTWireless Cellular Systems

The Internet of Things (IoT) is becoming a reality and with it comes the need to support more devices with better coverage and low power consumption on the wireless network. One of the Low-Power Wide Wan (LPWA) technologies that aims to meet these requirements is Narrow-Band IoT (NB-IoT). NB-IoT is a 4G cellular technology particularly focused on IoT scenarios demanding for low throughput and very low energy consumption. This dissertation investigates the capacity and performance of NB-IoT technology in real-world scenarios by comparing the results of measurements performed under different radio conditions around Lisbon’s metropolitan area. Inspired by related works presented in the dissertation, the approaches adopted in this work are explained and the metrics collected are described in detail. Through practical measurements campaigns we characterize different metrics of NB-IoT performance for different propagation scenarios, identifying hypothetical causes for the observed performance.A Internet das Coisas (IoT) está a tornar-se uma realidade e com ela surge uma necessidade de albergar mais dispositivos com melhor cobertura e menor consumo de energia nas redes sem fios. Uma das tecnologias Low-Power Wide Area (LPWA) que visa atender a esses requisitos é Narrow Band IoT (NB-IoT). NB-IoT é uma tecnologia celular 4G particularmente focada em cenários de IoT que exigem baixo débito e baixo consumo de energia. Esta dissertação investiga a capacidade e o desempenho da tecnologia NB-IoT em cenários do mundo real, comparando os resultados das medições realizadas sob diferentes condições de rádio na área metropolitana de Lisboa. Tomando como inspiração alguns trabalhos relacionados apresentados na dissertação, as abordagens adotadas neste trabalho são devidamente explicadas e as métricas descritas em detalhes. Através de medições práticas, são caracterizadas diferentes métricas de desempenho de NB-IoT para diferentes cenários de propagação, identificando causas hipotéticas para o desempenho observado

GROUPING NARROWBAND INTERNET OF THINGS END POINTS WITH CONTROL PACKETS BASED ON MULTICAST PACKET DELIVERY FUNCTIONALITY FROM ENODEB

Techniques are described herein to create a multicast Narrowband Internet of Things (NB-IOT) User Equipment (UE) group based on a set of four attributes that are not defined in the 3rd Generation Partnership Project (3GPP) Release 14 Standard/Specification. This NB-IOT UE grouping for multicast applications may assist indoor NB-IOT eNodeB (eNB) based deployments