Search

Bluetooth Low Energy (BLE) and IEEE 802.15.4 Time-Slotted Channel Hopping (TSCH) are widely used low-power standard technologies developed for short-range communications in the internet-of-things. In many applications, BLE and TSCH networks may be deployed in the vicinity of one another, which may lead to Cross Technology Interference (CTI) influencing each other's performance. Both technologies utilize channel hopping to alleviate the impact of external interferences. However, having a model to quantitatively estimate the performance of coexisting TSCH and BLE networks and analyze the role of networks' configuration settings is still an open problem. To address this, we provide a probabilistic analysis of collision-free communication of coexisting BLE and TSCH networks. Moreover, a fast coexistence simulation model is developed that computes the ratio of collision-free transmissions. This model is used to investigate how the performance of the coexisting networks may deviate from the results of the probabilistic analysis. It gives the designers a proper estimation of the worst case performance degradation due to such coexistence. It is shown that severity of the impact of coexisting BLE-TSCH networks on one another depends on the setup configurations and the relative timing of the two networks. The results show that these two technologies can coexist well with collision-free ratios of more than 92.58% and 96.29% in the tested configurations for TSCH and BLE, respectively.

Fine-grained frequencies have been used in several recent works to enhance network throughput as well as combat Cross Technology Interference (CTI) issues in licence free ISM bands. We observe that synchronous communication based strategies, due to the scope of inter-frequency capture-effect, are inherently more capable of supporting in-parallel communication over multiple channels even when the Center Frequency Distance (CFD) of the channels are very low (

Cross-Technology Interference affects the operation of low-power ZigBee networks, especially under severe WiFi interference. Accurate corruption estimation is very important to improve the resilience of ZigBee transmissions. However, there are many limitations in existing approaches such as low accuracy, high overhead, and requirement of hardware modification. In this paper, we propose an accurate corruption estimation approach, AccuEst, which utilizes per-byte SINR (Signal-to-Interference-and-Noise Ratio) to detect corruption. We combine the use of pilot symbols with per-byte SINR to improve corruption detection accuracy, especially in highly noisy environments (i.e., noise and interference are at the same level). We extract pilot symbols by leveraging protocol signatures. In addition, we design an adaptive pilot instrumentation scheme to strike a good balance between accuracy and overhead. We implement AccuEst on the TinyOS 2.1.1/TelosB platform and evaluate its performance through extensive experiments. Results show that AccuEst improves corruption detection accuracy by 79.4 percent on average compared with state-of-the-art approach (i.e., CARE) in highly noisy environments. In addition, AccuEst reduces pilot overhead by 83.7 percent on average compared to the traditional pilot-based approach. We implement AccuEst in a coding-based transmission protocol, and results show that with AccuEst, the packet delivery ratio is improved by 22.1 percent on average.

The ever-increasing deployment of Wi-Fi and ZigBee networks aggravates cross-technology interference (CTI) in the 2.4 GHz unlicensed spectrum. This letter presents a clean-slate technique, DOTA, to combat the CTI and enable ZigBee/Wi-Fi co-transmission. Unlike existing solutions merely handling Wi-Fi-to-ZigBee interference, DOTA accounts for the true sense of CTI wherein ZigBee and Wi-Fi interfere with each other. At the heart of DOTA lies two operations, signal polishing and pulse disambiguation, for decomposing and threading signal samples to recover contaminated ZigBee and Wi-Fi signals. Experiment results validate the feasibility of superiority of DOTA.

International audience; Several access technologies are expected to coexist and share the same spectrum portion for next-generation networks. However, to date, few tools exist in the literature when it comes to evaluating protocol performance in scenarios implying the coexistence of heterogeneous access technologies. We report herein, an extension of an open-source simulation framework for OMNeT++ (INET) to simulate interference impact on the coexistence of IEEE 802.11 and IEEE 802.15.4 in the 2.4GHz ISM bands. We extended the interference module of INET to take into account inter-technology and inter-channel interferences.

The growth of the Internet of Things (IoT) paradigm, popularized the use of wireless devices in the most diverse environments, creating the concept of Smart Environments (SE). SEs can be anything from a factory floor to our homes and are equipped with intelligent devices that automate most human activities. These devices suffer from the coexistence problem, as they often use the 2.4 GHz ISM band to communicate. In this context, this article presents the CASE algorithm to minimize interference in those environments through the proper allocation of wireless channels. The results suggest that the proposed algorithm reduces total interference as well as maximizes packet delivery when compared to existing approaches.

Localization of mobile nodes in wireless sensor networks (WSNs) is an active area of research. In this paper, we present a novel RSSI based localization algorithm for 802.15.4 (ZigBee) based WSNs. We propose and implement a novel range based localization algorithm to minimize cross technology interference operating in the same band. The goal is to minimize the mean square error of the localization algorithm. Hardware implementation of the algorithm is in agreement with ideal (no interference) simulation results where an accuracy of less than 0.5 m has been achieved.

Low power IoT suffers from performance degradation due to severe cross-technology interference (CTI) such as WiFi. In this demo, we present a novel ZigBee system that effectively maintains high reliability even under saturated WiFi traffic. This is achieved by placing a ZigBee packet on the guard band of ongoing, ambient WiFi traffic. Guard band is designed to be kept clear of interference from other WiFi, thereby safeguarding the ZigBee within. Our system effectively captures WiFi (802.11b) guard band on the fly, using physical layer information accessible on commodity ZigBee RF. We demonstrate real-time guard band detection and robust ZigBee communication, showcasing a practical pathway to operating low power IoT under excessive CTI.

The past years have witnessed the rapid conceptualization and development of wireless sensing based on Channel State Information (CSI) with commodity WiFi devices.Many research efforts have been devoted to promote WiFi sensing by innovating applications, refining models and optimizing algorithms. A critical issue of Cross-Technology Interference (CTI), however, is surprisingly unnoticed and largely unexplored in the existing literature. In this paper, we demonstrate that CTI poses severe impacts on CSI measurements and further degrades the performance of CSI-based sensing. Based on in-depth understanding of such impacts, we present PERFIC to deal with CTI for CSI on commercial WiFi. We first exploit the inherent cyclostationarity property of different signals to detect CTI and further identify the specific distorted subcarriers on CSI. For each interfered CSI, we then propose to mitigate the impacts of CTI by amending the abnormal subcarriers. We conduct experiments on typical wireless sensing applications, including human detection and activity classification, using off-the-shelf WiFi devices. The results demonstrate that PERFIC yields a remarkable performance gain of >30% with high efficiency and outperforms existing robust classifiers.By providing interference-free CSI that is amendable to existing and emerging CSI-based sensing applications, PERFIC underpins new insights for improving the sensitivity and reliability of wireless sensing.

In this paper, we show that inter-technology interference can be recognized using commodity WiFi devices by monitoring the statistics of receiver errors. Indeed, while for WiFi standard frames the error probability varies during the frame reception in different frame fields (PHY, MAC headers, and payloads) protected with heterogeneous coding, errors may appear randomly at any point during the time the demodulator is trying to receive an exogenous interfering signal. We thus detect and identify cross-technology interference on off-the-shelf WiFi cards by monitoring the sequence of receiver errors (bad PLCP, bad FCS, invalid headers, etc.) and propose two methods to recognize the source of interference based on artificial neural networks and hidden Markov chains. The result is quite impressive, reaching an average accuracy of over 95% in recognizing ZigBee, microwave, and LTE (in unlicensed spectrum) interference.

In recent years, the industrial, scientific, and medical (ISM) bands have been intensively shared with unlicensed wireless communications applications such as wireless sensor networks (WSNs). With flourishing popularity of sensor devices and increasing installation of wireless sensor nodes, the cross technology interference (CTI) has become a considerable real-world problem. Because of CTI, wireless devices suffer significant communication dilemma. Moreover, ISM band, as the main communication medium of WSN, should be reasonably utilized in an efficient and effective manner. Extensive approaches have been proposed to explore spectrum utilization in WSN. However, there is no such one, which systematically organizes these works. In this paper, we present a comprehensive survey on spectrum utilization in WSNs. To achieve this goal, We first illustrate the background of WSN and spectrum utilization. Our concern on CTI is then noted. Later we demonstrate the importance of efficient spectrum utilization. Eventually, through classification and summary of recent related works, we provide an essential structure of research in titled field and detailed intellectual merits of published works. Our survey covers more than 80 studies in the scope of spectrum utilization in WSN.

Cross-Technology Interference affects the operation of low-power ZigBee networks, especially under severe WiFi interference. Accurate corruption estimation is very important to improve the resilience of ZigBee transmissions. However, there are many limitations in existing approaches such as low accuracy, high overhead, and requiring hardware modification. In this paper, we propose an accurate corruption estimation approach, AccuEst, which utilizes per-byte SINR (Signal-to-Interferenceand-Noise Ratio) to detect corruption. We combine the use of pilot symbols with per-byte SINR to improve corruption detection accuracy, especially in highly noisy environments (i.e., noise and interference are at the same level). In addition, we design an adaptive pilot instrumentation scheme to strike a good balance between accuracy and overhead. We implement AccuEst on the TinyOS 2.1.1/TelosB platform and evaluate its performance through extensive experiments. Results show that AccuEst improves corruption detection accuracy by 78.6% on average compared with state-of-the-art approach (i.e., CARE) in highly noisy environments. In addition, AccuEst reduces pilot overhead by 53.7% on average compared to the traditional pilot-based approach. We implement AccuEst in a coding-based transmission protocol, and results show that with AccuEst, the packet delivery ratio is improved by 20.3% on average.

Recent studies show that high-power cross-technology interference is becoming a major problem in today's 802.11 networks. Devices like baby monitors and cordless phones can cause a wireless LAN to lose connectivity. The existing approach for dealing with such high-power interferers makes the 802.11 network switch to a different channel; yet the ISM band is becoming increasingly crowded with diverse technologies, and hence many 802.11 access points may not find an interference-free channel. This paper presents TIMO, a MIMO design that enables 802.11n to communicate in the presence of high-power cross-technology interference. Unlike existing MIMO designs, however, which require all concurrent transmissions to belong to the same technology, TIMO can exploit MIMO capabilities to decode in the presence of a signal from a different technology, hence enabling diverse technologies to share the same frequency band. We implement a prototype of TIMO in GNURadio-USRP2 and show that it enables 802.11n to communicate in the presence of interference from baby monitors, cordless phones, and microwave ovens, transforming scenarios with a complete loss of connectivity to operational networks.

Over the last few decades, we witnessed notable progress in wireless communication. This has led to rapid emergence of heterogeneous wireless technologies that share the RF spectrum in an un-coordinated way. Such a coexistence introduces high uncertainty and complexity to the medium, affecting reliability and availability of wireless net works. This problem aggravates for technologies operating in the lightly regulated, yet crowded ISM bands. To address coexistence of different technologies in the scarce RF spectrum, provide proper interference-aware protocols, and mitigation schemes, we need to develop a good understanding of the interaction patterns of these technologies. In this paper, we provide a thorough study of the implications of Cross Technology Interference (CTI) on the particularly vulnerable low-power IEEE 802.15.4 wireless networks. We identify the underlying vulnerabilities that hamper 802.15.4 to withstand CTI. We show that the uncertainty that CTI induces on the wireless channel is not completely stochastic; CTI exhibits distinct patterns that can be exploited by interference-aware protocols.