On the use of sniffers for spectrum occupancy measurements of Bluetooth low energy primary channels

The methods usually employed to measure channel occupancy show limitations in the context of Bluetooth Low Energy (BLE) advertisements. We propose and analyze the use of BLE sniffers as light and portable low-cost spectrum occupancy meters to be used in scenarios where real time signal analyzers are not adequate. For the measurement technique to be successful, several low-level effects must be considered. The paper argues about on-air time, receiving blind times due to processing and intra system interference, buffer saturation and frequency anchoring. Hence, a compensation procedure based on collision rate estimation is proposed. Results with the refined method show that occupancies of 40% can be measured with an overestimation error whose percentile 95% is 5 percentage points. This is reduced to 1.9 points when the occupancy is 15%. The sniffers perform in real time and are shown to correctly track short term load variations. The strategy has been successfully used to characterize occupancy in highly variable and loaded scenarios such as subway platforms and a shopping mall. Values up to 25% have been observed, which implies a relevant packet error rate. Hence, the tool can be used to make agile audits and configure the parameters that control communication redundancy in new or existing networks.The work by UPC has been funded by MCIN/ AEI /10.13039/501100011033 and by ERDF A way of making Europe, with the grant RTI2018-099880-B-C32 and PID2021-125799OA-I00. The work by I3A-UZ has been funded by MCIN/ AEI /10.13039/501100011033 and by ERDF A way of making Europe, with the grants RTI2018-095684-B-I00 and RTI2018-099063-B-I00, and by the Government of Aragon (Reference Group T31 20R).Peer ReviewedPostprint (published version

On the use of sniffers for spectrum occupancy measurements of Bluetooth low energy primary channels

The methods usually employed to measure channel occupancy show limitations in the context of Bluetooth Low Energy (BLE) advertisements. We propose and analyze the use of BLE sniffers as light and portable low-cost spectrum occupancy meters to be used in scenarios where real time signal analyzers are not adequate. For the measurement technique to be successful, several low-level effects must be considered. The paper argues about on-air time, receiving blind times due to processing and intra system interference, buffer saturation and frequency anchoring. Hence, a compensation procedure based on collision rate estimation is proposed. Results with the refined method show that occupancies of 40% can be measured with an overestimation error whose percentile 95% is 5 percentage points. This is reduced to 1.9 points when the occupancy is 15%. The sniffers perform in real time and are shown to correctly track short term load variations. The strategy has been successfully used to characterize occupancy in highly variable and loaded scenarios such as subway platforms and a shopping mall. Values up to 25% have been observed, which implies a relevant packet error rate. Hence, the tool can be used to make agile audits and configure the parameters that control communication redundancy in new or existing networks

Towards Efficient and Enhanced Wireless Coexistence in the Unlicensed Spectrum

The 3rd Generation Partnership Project (3GPP) is developing the fifth generation (5G) of wireless broadband technology and has identified the unlicensed spectrum as a principal item on the plan of action. Listen-Before-Talk (LBT) has been recognized as the starting development point for the channel access scheme of future 5G New Radio-Unlicensed (NR-U) networks. Recent technical reports suggest that all sub-7 GHz unlicensed spectrum is targeted for 5G NR-U operation, including the 2.4 GHz Industrial, Scientific, and Medical (ISM) band. Literature is inundated with research on Wi-Fi and LBT-based long-term evolution License-Assisted Access (LTE-LAA) wireless coexistence analysis. While a treasure trove of radio spectrum has been approved for license-exempt use in the 6 GHz band, industry and standard organizations must make sure it is well utilized by enhancing their coexistence schemes. A proper assessment of the homogeneous LBT deployment is imperative under the new use cases and regulatory circumstances. The work presented herein aimed to fill the gap and underline the importance of improving channel access mechanisms in next-generation wireless systems. The research in this dissertation first analyzed the LBT channel access scheme and analytically evaluated its performance in terms of a metrics set, such as effective channel utilization, collision probability, mean access delay, and temporal fairness among coexisting nodes. Outcomes of the developed analytical model revealed inefficiencies in various cases. For example, high priority classes generally hinder overall effective channel utilization, exhibit a high collision rate, and incur long latencies compared to lower priorities; and low priority classes sustain longer delays in class-heterogeneous scenarios. The developed framework was then utilized to investigate wireless coexistence in a 5G-enabled intensive care unit, employing remote patient monitoring over 5G NR-U. A modified LBT scheme is then proposed in this work to enhance overall channel efficiency in homogeneous LBT deployments by reducing the collision probability among coexisting stations based on the analytical investigation of the LBT mechanism. It is expected that low-power, narrowband frequency hoppers will be allowed to operate in the 6 GHz spectrum based on recent European Communications Committee (ECC) mandates, which raises speculation around coexistence with incumbent radio access technologies (RATs). To address the potential operation of cellular LBT in the 2.4 GHz and frequency hopping systems in the 5- and 6-GHz bands, the coexistence of Bluetooth Low Energy (BLE) 5 and LBT was investigated empirically in an anechoic chamber. The mutual impact was explored by means of throughput, packet error rate, and interframe delays. Empirical evaluation results demonstrated how BLE throughput dropped as the intended-to-unintended signal ratio decreased and the way in which LBT classes exhibited a diminishing effect as the class priority descended. Long Range BLE physical layer (PHY) was found to sustain longer gap times (i.e., delay) than the other two PHYs; however, the LR PHY showed less susceptibility to interference. Results also demonstrated that low data rate BLE PHYs hindered LBT throughput performance since they correspond to longer airtime durations

Practical Extensions to the Evaluation and Analysis of Wireless Coexistence in Unlicensed Bands

Sharing spectrum resources in unlicensed bands has proven cost effective and beneficial for providing ubiquitous access to wireless functionality for a broad range of applications. Chipsets designed to implement communication standards in the Industrial, Scientific and Medical (ISM) band have become increasingly inexpensive and widely available, making wireless-enabled medical and non-medical devices attractive to an increased number of users. Consequently, wireless coexistence becomes a concern. In response, the U.S. Food and Drug Administration (FDA) has issued a guidance document to assist medical device manufacturers ensure reasonable safety and effectiveness. Coexistence-testing methods are now being reported in literature, and novel solutions are under consideration for inclusion in the American National Standards Institute (ANSI) C63.27 Standard for Evaluation of Wireless Coexistence. This dissertation addresses practical issues for evaluating and reporting wireless coexistence. During testing, an under-test-system (UTS) is evaluated in the presence of an interfering system (IS). Accordingly, an innovative method is suggested for estimating channel utilization of multiple, concurrent wireless transmitters sharing an unlicensed band in the context of radiated open environment coexistence testing (ROECT). Passively received power measurements were collected, and then a Gaussian mixture model (GMM) was used to build a classifier for labeling observed power samples relative to their source. Overall accuracy was verified at 98.86%. Case studies are presented utilizing IEEE 802.11n as an IS with UTS based on either IEEE 802.11n or ZigBee. Results demonstrated the mutual effect of spectrum sharing on both IS and UTS in terms of per-second channel utilization and frame collision. The process of approximating the probability of a device to coexist in its intended environment is discussed, and a generalized framework for modeling the environment is presented. An 84-day spectrum survey of the 2.4 GHz to 2.48 GHz ISM band in a hospital environment serves as proof of concept. A custom platform was used to monitor power flux spectral density and record received power in both an intensive care unit (ICU) and a post-surgery recovery room (RR). Observations indicated that significant correlation in activity patterns corresponded mainly to IEEE 802.11 channels 1, 6, and 11. Consequently, channel utilization of three non-overlapping channels of 20 MHz bandwidth---relative to IEEE 802.11 channels 1, 6, and 11---were calculated and fitted to a generalized extreme value (GEV) distribution. Low channel utilization ( 50%), was observed in the surveyed environment. Reported findings can be complementary to wireless coexistence testing. Quantifying the probability of UTS coexistence in a given environment is central to the evaluation of coexistence, as evidenced in the draft of the C63.27 standard. Notably, a method for this calculation is not currently provided in the standard. To fill this void, the work presented herein proposes the use of logistic regression (LR) to estimate coexistence probability. ROECT was utilized to test a scenario with an 802.11n IS and ZigBee UTS medical device. Findings demonstrate that fitted LR model achieves 92.72% overall accuracy of classification on a testing dataset that included the outcome of a wide variety of coexistence testing scenarios. Results were incorporated with those reported in [1] using Monte Carlo simulation to estimate UTS probability of coexistence in a hospital environment

Low-Power Wide-Area Networks: A Broad Overview of its Different Aspects

Low-power wide-area networks (LPWANs) are gaining popularity in the research community due to their low power consumption, low cost, and wide geographical coverage. LPWAN technologies complement and outperform short-range and traditional cellular wireless technologies in a variety of applications, including smart city development, machine-to-machine (M2M) communications, healthcare, intelligent transportation, industrial applications, climate-smart agriculture, and asset tracking. This review paper discusses the design objectives and the methodologies used by LPWAN to provide extensive coverage for low-power devices. We also explore how the presented LPWAN architecture employs various topologies such as star and mesh. We examine many current and emerging LPWAN technologies, as well as their system architectures and standards, and evaluate their ability to meet each design objective. In addition, the possible coexistence of LPWAN with other technologies, combining the best attributes to provide an optimum solution is also explored and reported in the current overview. Following that, a comparison of various LPWAN technologies is performed and their market opportunities are also investigated. Furthermore, an analysis of various LPWAN use cases is performed, highlighting their benefits and drawbacks. This aids in the selection of the best LPWAN technology for various applications. Before concluding the work, the open research issues, and challenges in designing LPWAN are presented.publishedVersio

A Survey on Layer-Wise Security Attacks in IoT: Attacks, Countermeasures, and Open-Issues

© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).Security is a mandatory issue in any network, where sensitive data are transferred safely in the required direction. Wireless sensor networks (WSNs) are the networks formed in hostile areas for different applications. Whatever the application, the WSNs must gather a large amount of sensitive data and send them to an authorized body, generally a sink. WSN has integrated with Internet-of-Things (IoT) via internet access in sensor nodes along with internet-connected devices. The data gathered with IoT are enormous, which are eventually collected by WSN over the Internet. Due to several resource constraints, it is challenging to design a secure sensor network, and for a secure IoT it is essential to have a secure WSN. Most of the traditional security techniques do not work well for WSN. The merger of IoT and WSN has opened new challenges in designing a secure network. In this paper, we have discussed the challenges of creating a secure WSN. This research reviews the layer-wise security protocols for WSN and IoT in the literature. There are several issues and challenges for a secure WSN and IoT, which we have addressed in this research. This research pinpoints the new research opportunities in the security issues of both WSN and IoT. This survey climaxes in abstruse psychoanalysis of the network layer attacks. Finally, various attacks on the network using Cooja, a simulator of ContikiOS, are simulated.Peer reviewe