Theoretical Analysis of UNB-based IoT Networks with Path Loss and Random Spectrum Access

International audienceUNB is dedicated to long range and low power transmission in IoT networks. The channel access is Random-FTMA, where nodes select their time and frequency in a random and continuous way. This randomness leads to a new behavior of the interference which has not been theoretically analyzed yet, when considering the pathloss of nodes located randomly in an area. In this paper, in order to quantify the system performance, we derive and exploit a theoretical expression of the packet error rate in a UNB based IoT network, when taking into account both interference due to the spectral randomness and path loss due to the propagation

Spectrum Sharing for Massive Access in Ultra-Narrowband IoT Systems

Ultra-narrowband (UNB) communications has become a signature feature for many emerging low-power wide-area (LPWA) networks. Specifically, using extremely narrowband signals helps the network connect more Internet-of-things (IoT) devices within a given band. It also improves robustness to interference, extending the coverage of the network. In this paper, we study the coexistence capability of UNB networks and their scalability to enable massive access. To this end, we develop a stochastic geometry framework to analyze and model UNB networks on a large scale. The framework captures the unique characteristics of UNB communications, including the asynchronous time-frequency access, signal repetition, and the absence of base station (BS) association. Closed-form expressions of the transmission success probability and network connection density are presented for several UNB protocols. We further discuss multiband access for UNB networks, proposing a low-complexity protocol. Our analysis reveals several insights on the geographical diversity achieved when devices do not connect to a single BS, the optimal number of signal repetitions, and how to utilize multiple bands without increasing the complexity of BSs. Simulation results are provided to validate the analysis, and they show that UNB communications enables a single BS to connect thousands of devices even when the spectrum is shared with other networks.Comment: This paper is accepted for publication in the IEEE Journal on Selected Areas in Communications. arXiv admin note: text overlap with arXiv:1811.1109

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

LPWAN technologies for IoT systems: choice between ultra narrow band and spread spectrum

Low Power Wide Area Network (LPWAN) is imperative for the expansion and development of IoT networks and their connectivity infrastructure. This far-reaching connectivity of low power devices that are placed virtually anywhere is evolving a new things-based business model. This things-based business model has certain requirements such as long range, extended battery life and very low end point cost. LPWAN technologies have successfully addressed these IoT requirements and are receiving wider acceptance in the IoT industry. In most LPWAN technologies, two main alternative communication techniques, Ultra Narrow Band (UNB) and Spread Spectrum (SS) are used at the physical layer. However, the greatest dilemma is the selection of the most suitable technique from UNB and SS for LPWAN. This paper addresses this selection dilemma of UNB and SS by examining some of the most critical factors responsible for the performance of LPWAN technologies such as interference, capacity, link budget and coexistence. Furthermore, it evaluates the most popular UNB-based LPWAN technologies Sigfox and Telensa, and SS-based LPWAN technologies LoRa and RPMA investigating their strengths and limitations for IoT applications

Up-Link Capacity Derivation for Ultra-Narrow-Band IoT Wireless Networks

International audienceThanks to its low energy consumption and very long range (upto 50 km in free-space), ultra-narrow-band transmission (UNB) represents apromising alternative to classical technologies used in cellular networks to servelow-throughput wireless sensor networks (WSNs) and the Internet of things(IoT). In UNB, nodes access to the medium by selecting their frequency ina random and continuous way. This randomness leads to new behavior inthe interference which has not been theoretically analyzed, when consideringthe pathloss of nodes randomly deployed around the receiver. In this paper, inorder to quantify the system performance, we derive and exploit two theoreticalexpressions of the outage probability in a UNB based IoT network, accountingfor both interference due to the spectral randomness and path loss due to thepropagation (with and without Rayleigh fading). This enables us to estimatethe network capacity as a function of the path-loss exponent, by determiningthe maximum number of simultaneous supported nodes. We highlight that thebandwidth should be chosen based on the propagation channel properties

On the benefits of successive interference cancellation for ultra narrow band networks : Theory and application to IoT

International audienceUNB (Ultra Narrow Band) stands out as one promising PHY solution for low-power, low-throughput and long-range IoT. The dedicated MAC scheme is RFTMA (Random Frequency and Time Multiple Access), where nodes access the channel randomly both in frequency and in time domain, without prior channel sensing. This blind randomness sometimes introduces interference and packet losses. Hence, in this paper, we propose to use the well-known SIC (Successive Interference Cancellation) to cancel the interference in a recursive way. We provide a theoretical analysis of network performance, when considering jointly SIC and the specific spectral randomness of UNB. We analytically and numerically highlight the SIC efficiency in enhancing UNB system performance