1,412 research outputs found
Scalability analysis of large-scale LoRaWAN networks in ns-3
As LoRaWAN networks are actively being deployed in the field, it is important
to comprehend the limitations of this Low Power Wide Area Network technology.
Previous work has raised questions in terms of the scalability and capacity of
LoRaWAN networks as the number of end devices grows to hundreds or thousands
per gateway. Some works have modeled LoRaWAN networks as pure ALOHA networks,
which fails to capture important characteristics such as the capture effect and
the effects of interference. Other works provide a more comprehensive model by
relying on empirical and stochastic techniques. This work uses a different
approach where a LoRa error model is constructed from extensive complex
baseband bit error rate simulations and used as an interference model. The
error model is combined with the LoRaWAN MAC protocol in an ns-3 module that
enables to study multi channel, multi spreading factor, multi gateway,
bi-directional LoRaWAN networks with thousands of end devices. Using the
lorawan ns-3 module, a scalability analysis of LoRaWAN shows the detrimental
impact of downstream traffic on the delivery ratio of confirmed upstream
traffic. The analysis shows that increasing gateway density can ameliorate but
not eliminate this effect, as stringent duty cycle requirements for gateways
continue to limit downstream opportunities.Comment: 12 pages, submitted to the IEEE Internet of Things Journa
Survey on wireless technology trade-offs for the industrial internet of things
Aside from vast deployment cost reduction, Industrial Wireless Sensor and Actuator Networks (IWSAN) introduce a new level of industrial connectivity. Wireless connection of sensors and actuators in industrial environments not only enables wireless monitoring and actuation, it also enables coordination of production stages, connecting mobile robots and autonomous transport vehicles, as well as localization and tracking of assets. All these opportunities already inspired the development of many wireless technologies in an effort to fully enable Industry 4.0. However, different technologies significantly differ in performance and capabilities, none being capable of supporting all industrial use cases. When designing a network solution, one must be aware of the capabilities and the trade-offs that prospective technologies have. This paper evaluates the technologies potentially suitable for IWSAN solutions covering an entire industrial site with limited infrastructure cost and discusses their trade-offs in an effort to provide information for choosing the most suitable technology for the use case of interest. The comparative discussion presented in this paper aims to enable engineers to choose the most suitable wireless technology for their specific IWSAN deployment
Experimental Analysis of IoT Networks Based on LoRa/LoRaWAN under Indoor and Outdoor EnvirMedusonments: Performance and Limitations
Nowadays, Internet of Things (IoT) has multiple applications in different fields. This concept allows physical devices to connect to the internet in order to establish a strong infrastructure that facilitates many device control and monitoring tasks. Low Power Wide Area (LPWA) communication protocols become widely used for IoT networks because of their low power consumption and the broad range communication. LPWA enables devices to transmit small amounts of data in a long distance. Among LPWA protocols, LoRa technology gained a lot of interest recently from the research community and many companies. LoRa is a long range and low power wireless communication technology regulated by the LoRaWAN standard. It can be o good candidate to deploy node network where long distance and extended battery life is required. A LoRaWAN architecture is deployed in a star-of-stars topology and based on a systematic evaluation of a long-term operation of the network monitoring. This works describes experimental results of testing LoRa in indoor and outdoor environments to understand how it works, evaluate its performance, and limitations. As expected, results show that LoRa performs better outdoor. It is also interesting to note that elevating the gateway in order to have a free line of sight with the IoT node, or close to it, increases the signal quality received by the end-node devices, and consequently, longer distances can be achieved
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
Efficient Ambient LoRa Backscatter with On-Off Keying Modulation
Backscatter communication holds potential for ubiquitous and low-cost
connectivity among low-power IoT devices. To avoid interference between the
carrier signal and the backscatter signal, recent works propose a
frequency-shifting technique to separate these two signals in the frequency
domain. Such proposals, however, have to occupy the precious wireless spectrum
that is already overcrowded, and increase the power, cost, and complexity of
the backscatter tag. In this paper, we revisit the classic ON-OFF Keying (OOK)
modulation and propose Aloba, a backscatter system that takes the ambient LoRa
transmissions as the excitation and piggybacks the in-band OOK modulated
signals over the LoRa transmissions. Our design enables the backsactter signal
to work in the same frequency band of the carrier signal, meanwhile achieving
flexible data rate at different transmission range. The key contributions of
Aloba include: (1) the design of a low-power backscatter tag that can pick up
the ambient LoRa signals from other signals. (2) a novel decoding algorithm to
demodulate both the carrier signal and the backscatter signal from their
superposition. We further adopt link coding mechanism and interleave operation
to enhance the reliability of backscatter signal decoding. We implement Aloba
and conduct head-to-head comparison with the state-of-the-art LoRa backscatter
system PLoRa in various settings. The experiment results show Aloba can achieve
199.4 Kbps data rate at various distances, 52.4 times higher than PLoRa
Variable link performance due to weather effects in a long-range, low-power LoRa sensor network
When aiming for the wider deployment of low-power sensor networks, the use of sub-GHz frequency bands shows a lot of promise in terms of robustness and minimal power consumption. Yet, when deploying such sensor networks over larger areas, the link quality can be impacted by a host of factors. Therefore, this contribution demonstrates the performance of several links in a real-world, research-oriented sensor network deployed in a (sub)urban environment. Several link characteristics are presented and analysed, exposing frequent signal deterioration and, more rarely, signal strength enhancement along certain long-distance wireless links. A connection is made between received power levels and seasonal weather changes and events. The irregular link performance presented in this paper is found to be genuinely disruptive when pushing sensor-networks to their limits in terms of range and power use. This work aims to give an indication of the severity of these effects in order to enable the design of truly reliable sensor networks
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