Bluetooth Low Energy Research Articles

Collaborative Indoor Positioning by Localization Comparison at an Encounter Position

With the widespread use of smartphones, there is a surging demand for localization in indoor environments. The main challenges are the requirement of special equipment (e.g., a map database and Wi-Fi access points) and error accumulation for indoor localization. In this paper, we propose a novel collaborative indoor positioning method to reduce error accumulation. Estimated positions are corrected using the collaborator’s positions when an encounter is detected by communication based on Bluetooth Low Energy (BLE). In addition, a map is obtained by taking photos of information boards. Therefore, the proposed method needs smartphones only; other equipment is not required. We obtained an accurate localization comparison using a machine learning model. The experimental results showed that the proposed method achieved reliable encounter communication in eight facilities. The collaborative localization method successfully enhanced position estimations. Specifically, the proposed method outperformed the existing baseline method by 13.0% in accuracy of indoor positioning.

A Service-Aware Scheme for Improving Channel Selectivity of BLE Beacon Advertising

As Bluetooth Low Energy (BLE) is a low-cost wireless technology, it has emerged to dominate a beacon technology market. BLE advertising is a critical part of the protocol that can broadcast messages to nearby scanners. Based on BLE 5.0 specification promising new functionality for connectionless services, the wide-ranging enhancements implemented in BLE advertising mechanisms open unlimited possibilities for more advanced beacons. For the advertising packets, beacons can increase the payload size or use chained packets so that more content can be provided in an advertising event. However, the channel selection algorithms in BLE do not support the transmission of diverse extended advertisements. The packets of different advertising events that need to be transmitted on specific channels should be considered for better transmission efficiency. In this paper, we give a clear classification of advertising services for BLE beacons, propose simple channel selectivity schemes to improve the service ratio, and show an analytical model to study the blocking probability of the BLE advertising network. In addition, we use this analytical model to identify the blocking performance of the network. Simulation results validated by the analytical model show that the proposed schemes improve the transmission efficiency of advertising services in BLE beacons.

Análisis del cumplimiento de Bluetooth 5 con los requisitos de IoT de la UIT

Bluetooth is an open, short-range, and low power Wireless technology, which aims to simplify communication between different kinds of devices. Bluetooth has five versions, divided into two main operation modes, Classic Bluetooth and Bluetooth Low Energy (BLE). BLE is designed for the use of IoT (Internet of Things) applications. The fifth version of Bluetooth improves all the features to surpass other technologies that want to be the base of IoT communications. Bluetooth 5 achieves greater range, higher data transmission speed, improved support for advertising, and energy efficiency than previous versions. The new mesh topology feature makes Bluetooth a good candidate for IoT communications since it allows decentralized architectures. In this work, a revision of the Bluetooth version 5 is carried out. Furthermore, the IoT's operating requirements, based on the recommendations of ITU (International Telecommunication Union), are presented. The contribution of this work is the analysis of the characteristics of Bluetooth 5 to determine whether or not they meet the IoT requirements proposed by the ITU. The analysis results indicate that Bluetooth 5 meets the high-level requirements and approximately half of each category's standard IoT requirements.

Improved Spectrum Coexistence in 2.4 GHz ISM Band Using Optimized Chaotic Frequency Hopping for Wi-Fi and Bluetooth Signals.

Efficiently managing coexistence is crucial for achieving high-quality wireless communication in the Industrial, Scientific, and Medical (ISM) band where multiple wireless communication systems operate. Coexistence problems between Wi-Fi and Bluetooth Low Energy (BLE) signals are especially significant due to their shared frequency band, which often leads to interference and a reduced performance for both systems. Therefore, effective coexistence management strategies are essential for ensuring the optimal performance of Wi-Fi and Bluetooth signals in the ISM band. In this paper, the authors conducted a study to investigate coexistence management in the ISM band by evaluating four frequency hopping techniques: random, chaotic, adaptive, and an optimized chaotic technique proposed by the authors. The optimized chaotic technique aimed to minimize interference and ensure zero self-interference among hopping BLE nodes by optimizing the update coefficient. Simulations were conducted in an environment with existing Wi-Fi signal interference and interfering Bluetooth nodes. The authors compared several performance metrics, including the total interference rate, total successful connection rate, and trial execution time for channel selection processing time. The results indicated that the proposed optimized chaotic frequency hopping technique achieved a better balance between reducing interference with Wi-Fi signals, achieving a high success rate for connecting BLE nodes, and requiring minimal trial execution time. This makes it a suitable technique for managing interference in wireless communication systems. While the proposed technique had a higher interference than the adaptive technique for small numbers of BLE nodes, for larger numbers of nodes it had a much lower interference than the adaptive technique. The proposed optimized chaotic frequency hopping technique provides a promising solution for effectively managing coexistence in the ISM band, particularly between Wi-Fi and BLE signals. It has the potential to improve the performance and quality of wireless communication systems.

Direction of arrival estimation for BLE: Antenna array design and evaluation

The use of smart antenna arrays in wireless communication systems is becoming increasingly popular, as they improve the performance of the radio link and allow the integration of communication and sensing functions. In this paper, we present the design and performance evaluation of a uniform circular antenna array (UCAA) with 12 monopole antennas and RF switches to select the active antenna for the signal direction of arrival (DoA) estimation. The antenna configuration was optimized through simulations for a different number of antennas and antenna array radius. The frequency tuning of the antennas considered the coupling of the active antenna with adjacent antennas. The performance of the antenna array was evaluated by (1) simulations that examined the proximity of the antenna to the edge of the antenna array and the influence of adjacent antennas on the performance of the active antenna, and (2) measurements in outdoor and indoor environments. The results of the simulations show that antenna coupling can cause nulls in the radiation pattern, which affects the DoA estimation by reducing the signal-to-noise ratio. In a semi-controlled environment, we achieved a DoA estimation error of less than 1 degree by using the Bluetooth Low Energy (BLE) Angle of Arrival feature.

An Energy-Efficient Flexible Multi-Modal Wireless Sweat Sensing System Based on Laser Induced Graphene

Real-time sweat monitoring is vital for athletes in order to reflect their physical conditions, quantify their exercise loads, and evaluate their training results. Therefore, a multi-modal sweat sensing system with a patch-relay-host topology was developed, which consisted of a wireless sensor patch, a wireless data relay, and a host controller. The wireless sensor patch can monitor the lactate, glucose, K+, and Na+ concentrations in real-time. The data is forwarded via a wireless data relay through Near Field Communication (NFC) and Bluetooth Low Energy (BLE) technology and it is finally available on the host controller. Meanwhile, existing enzyme sensors in sweat-based wearable sports monitoring systems have limited sensitivities. To improve their sensitivities, this paper proposes a dual enzyme sensing optimization strategy and demonstrates Laser-Induced Graphene (LIG)-based sweat sensors decorated with Single-Walled Carbon Nanotubes (SWCNT). Manufacturing an entire LIG array takes less than one minute and costs about 0.11 yuan in materials, making it suitable for mass production. The in vitro test result showed sensitivities of 0.53 μA/mM and 3.9 μA/mM for lactate and glucose sensing, and 32.5 mV/decade and 33.2 mV/decade for K+ and Na+ sensing, respectively. To demonstrate the ability to characterize personal physical fitness, an ex vivo sweat analysis test was also performed. Overall, the high-sensitivity lactate enzyme sensor based on SWCNT/LIG can meet the requirements of sweat-based wearable sports monitoring systems.

An Autonomous IoT-Based Contact Tracing Platform in a COVID-19 Patient Ward

Since 2020, the coronavirus disease (COVID-19) pandemic has had a substantial impact on all community sectors worldwide, particularly the health care sector. Healthcare workers (HCWs) are at risk of COVID-19 infection due to occupational exposure to infectious patients, visitors, and staff. Contact tracing of close physical interaction is an essential control measure, especially in hospitals, to prevent onward transmission during an outbreak event. In this article, we propose an IoT-based contact tracing system for subject identification, interaction tracking and data transmission in hospital wards. The system, based on Bluetooth Low Energy (BLE) devices, tracks the duration of interactions between different HCWs, and the time each HCW spends within the patient rooms using additional information from proximity sensors in the hallway or on the door frame of the patient room. The collected data are transferred via Long Range (LoRa) wireless technology and further analyzed to inform infection prevention activities. The suggested system’s performance is evaluated in a COVID-19 patient ward with both standard and negative pressure isolation rooms, and the current system’s capabilities and future research prospects are briefly discussed.

BLE beacon-based floor detection for mobile robots in a multi-floor automation laboratory

Abstract As an important task of multi-floor localization, floor detection has elicited great attention. Wireless infrastructures like Wi-Fi and Bluetooth Low Energy (BLE) play important roles in floor detection. However, most floor detection research tends to focus on data modelling but pays little attention to the data collection system, which is the basis of wireless infrastructure-based floor detection. In fact, the floor detection task can be greatly simplified with proper data collection system design. In this paper, a floor detection solution is developed in a multi-floor life science automation lab. A data collection system consisting of BLE beacons, a receiver node and an Internet of Things (IoT) cloud is provided. The features of the BLE beacon under different settings are evaluated in detail. A mean filter is designed to deal with the fluctuation of the received signal strength indicator data. A simple floor detection method without a training process was implemented and evaluated in more than 100 floor detection tests. The time delay and floor detection accuracy under different settings are discussed. Finally, floor detection is evaluated on the H20 multi-floor transportation robot. Two sensor nodes are installed on the robot at different heights. The floor detection performance with different installation heights is discussed. The experimental results indicate that the proposed floor detection method provides floor detection accuracy of 0.9877 to 1 with a time delay of 5 s.

Post-mortem digital forensics analysis of the Zepp Life android application

This paper studies the post-mortem digital forensic artifacts left by the Android ZeppLife (formerly MiFit) mobile application when used in conjunction with a Xiaomi MiBand 6. The MiBand 6 is a low-cost smart band device with several sensors that allow for health and activity monitoring, collecting metrics such as heart rate, blood oxygen saturation level, and step count. The device communicates via Bluetooth Low Energy with the ZeppLife application, which displays its data, provides some controls, and acts as a bridge to the Internet.We study, from a digital forensics perspective, the Android version of the mobile application in a rooted smartphone. For this purpose, we analyze the data repositories, namely its databases and XML files, and correlate the data on the smartphone with the corresponding usage of the Mi Band device. The paper also presents two open-source scripts we have developed to ease the task of forensic practitioners dealing with ZeppLife/MiBand 6: ZL_std and ZL_autopsy. The former refers to a Python 3 script that extracts high-level views of Zepp Life data through the command-line, whereas the latter is a module that integrates ZL_std functionalities within the popular open-source Autopsy digital forensic software. Data stored on the Android companion device of a MiBand 6 might include GPS coordinates, events and alarms, and biometric data such as heart rate, sleep time, and fitness activity, which can be valuable digital forensic artifacts.

PLL Fractional Spur’s Impact on FSK Spectrum and a Synthesizable ADPLL for a Bluetooth Transmitter

In this work, we present an open-source fully-synthesizable fractional-N all-digital phase-locked loop (ADPLL) designed for a Bluetooth low-energy (BLE) transmitter (TX) along with a semi-analytical model of the PLL fractional spur’s impact on the BLE output spectrum. Based on the model and the BLE specification for spur emission, a requirement for the PLL fractional spurs is derived. To meet the derived spectral mask by reducing the fractional spurs, a novel synthesizable two-step time to digital converter (TSTDC) that employs embedded TDC (EMBTDC) as coarse and Vernier delay-line TDC (DLTDC) as fine TDC is proposed. We also present a digital calibration scheme to compensate for the nonlinearity induced by the place-and-route (P&R) tool. The PLL is fabricated in 12-nm FinFET and demonstrated in a BLE-TX. The measured BLE transmissions satisfy the standard requirements thanks to the reduced fractional spurs. In a standalone PLL mode, the proposed TSTDC and calibration scheme reduced the fractional spurs by 14.3 dB compared to only using an EMBTDC in near-integer <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$</tex-math> </inline-formula> operation. The PLL supports a frequency range of 1.8–2.7 GHz and consumes 3.91 mW at 2.4006 GHz achieving figure of merit (FoM) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 220.7 dB in fractional-N mode with a 40 MHz reference, occupying an area of 0.063 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}$</tex-math> </inline-formula> . A highly automated design flow is used for the PLL to lower the barrier for new developers and reduce the porting cost.

Development of real-time monitoring BLE-LoRa positioning system based on RSSI for non-line-of-sight condition

Indoor positioning has become popular in this decade and is used to locate users or objects in indoor environments. This is because global positioning system (GPS) is not efficient for indoor use due to the multipath fading effect. This research is about development bluetooth low energy (BLE) indoor positioning system with the aid of long range (LoRa) network and guideline on selection of the BLE beacons. Next, positioning systems are developed consisting of BLE beacons, a transceiver of hybrid BLE-LoRa module, a LoRa receiver and Raspberry Pi as real-time monitoring. The received signal strength indicator (RSSI) and BLE Mac address from BLE beacons received via LoRa network are analyzed using the positioning algorithm designed in MATLAB. The positioning algorithm incorporates distance estimation, filter implementation and trilateration technique. The estimated location is analyzed with the root mean square error (RMSE) and cumulative distribution function (CDF). According to the results, implementing the filter reduces the positioning accuracy error, achieving 90% accuracy of positioning error less than 1.20 meters for the whole testbed. Finally, the algorithm is embedded into Raspberry Pi to view the location via desktop.

JECP: Joint Energy Conservation and Collision Avoidance for Path Construction in Bluetooth Networks

With the growing elderly population of the world population, the number of elderly people who live alone is continuously growing. Providing them with high-quality healthcare has become a major concern nowadays. In order to detect the elderly people’s sudden danger of elderly living alone, this paper proposes a path construction mechanism, called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">JECP</i> , which aims to conserve energy and avoid collision for the emergent sensors in Bluetooth mesh networks. In case that the emergent sensors are deployed in the same room, the proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">JECP</i> constructs disjoint paths to avoid collisions, which are triggered by the same emergent event at the same time. The other case is that the emergent sensors are deployed in different rooms. The probability that these emergent sensors are triggered by the same event is very small. Hence the proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">JECP</i> constructs the best emergent path that shares the general sensors as much as possible to save energy consumption. The experimental results show that the proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">JECP</i> outperforms the existing mechanisms in terms of transmission delay and energy consumption for the emergent sensors in Bluetooth Low Energy (BLE) networks.

BLE-based secure tracking system proposal

As communication capabilities of mobile devices continue to advance, ensuring reliability and security has become increasingly crucial. The aerial tracking system presented in this paper provides a useful solution for tracking and tracing objects in various scenarios. To ensure reliability and security, the system incorporates appropriate mechanisms, including Lightweight Cryptography, to prioritize confidentiality and integrity. The Android component of the system has two modes of operation: Tracker Mode, running on a smartphone mounted on a drone (RPA), and Client Mode, running on mobile devices on the ground. In Client Mode, users transmit their positioning and trajectory information via Bluetooth Low Energy beacon mode, which is then relayed to the server backend via the 4G/5G network once the RPA enters an area with coverage. The system provides a reliable and secure solution for situations where tracking and tracing are essential, such as the supervision and control of public areas with capacity control or tracking and localizing people in isolated environments.

A wireless and battery-less implant for multimodal closed-loop neuromodulation in small animals.

Fully implantable wireless systems for the recording and modulation of neural circuits that do not require physical tethers or batteries allow for studies that demand the use of unconstrained and freely behaving animals in isolation or in social groups. Moreover, feedback-control algorithms that can be executed within such devices without the need for remote computing eliminate virtual tethers and any associated latencies. Here we report a wireless and battery-less technology of this type, implanted subdermally along the back of freely moving small animals, for the autonomous recording of electroencephalograms, electromyograms and body temperature, and for closed-loop neuromodulation via optogenetics and pharmacology. The device incorporates a system-on-a-chip with Bluetooth Low Energy for data transmission and a compressed deep-learning module for autonomous operation, that offers neurorecording capabilities matching those of gold-standard wired systems. We also show the use of the implant in studies of sleep-wake regulation and for the programmable closed-loop pharmacological suppression of epileptic seizures via feedback from electroencephalography. The technology can support a broader range of applications in neuroscience and in biomedical research with small animals.

Application-Layer Time Synchronization and Data Alignment Method for Multichannel Biosignal Sensors Using BLE Protocol.

Wearable wireless biomedical sensors have emerged as a rapidly growing research field. For many biomedical signals, multiple sensors distributed about the body without local wired connections are required. However, designing multisite systems at low cost with low latency and high precision time synchronization of acquired data is an unsolved problem. Current solutions use custom wireless protocols or extra hardware for synchronization, forming custom systems with high power consumption that prohibit migration between commercial microcontrollers. We aimed to develop a better solution. We successfully developed a low-latency, Bluetooth low energy (BLE)-based data alignment method, implemented in the BLE application layer, making it transferable between manufacturer devices. The time synchronization method was tested on two commercial BLE platforms by inputting common sinusoidal input signals (over a range of frequencies) to evaluate time alignment performance between two independent peripheral nodes. Our best time synchronization and data alignment method achieved absolute time differences of 69 ± 71 μs for a Texas Instruments (TI) platform and 477 ± 490 μs for a Nordic platform. Their 95th percentile absolute errors were more comparable-under 1.8 ms for each. Our method is transferable between commercial microcontrollers and is sufficient for many biomedical applications.

Possibilities of Using Bluetooth Low Energy Beacon Technology to Locate Objects Internally: A Case Study

The developments that are occurring in relation to Industry 4.0 are making it possible to automate a huge number of production activities. Automation includes the possibility of automatically identifying individual elements of a system. One of the options for doing this involves the use of Bluetooth Low Energy technology. The system’s advantages lie in its wide availability, economic simplicity, ability to design individual system elements, and overall system architecture. The system applied in the case study presented in this article consisted of beacons from Accent Systems and identification gateways based on the Raspberry Pi Zero W device. During several hours of testing, the functionality and reliability of all system components was demonstrated. The measurements showed that the system was able to determine the distance from a gate in line of sight with 94% accuracy. With regards to indirect visibility, when a metal crate was used to shield the beacon from the gateway, the system was able to determine the exact distance only 22% of the time. However, the variance between the actual and measured values was found to be small, therefore proving sufficient for most use cases. The major advantage of Bluetooth Low Energy beacons, and Bluetooth technology in general, is its massive ubiquity in the market. Since the Bluetooth module is part of every smartphone, this system can be made available to a wide range of users.

Thermoelectric energy harvesting for wireless onboard rail condition monitoring

ABSTRACT A thermoelectric energy harvesting device is evaluated to power a bearing health monitoring system. Unlike wayside equipment, the new system is an onboard wireless solution utilizing accelerometer and temperature sensors to assess the bearing condition continuously. The harvesting system consists of two thermoelectric generator modules with aluminium heat sinks, a switching boost converter, a battery management circuit, and a lithium rechargeable battery. The performance of the harvester is validated on an AAR class bearing mounted on a laboratory tester, with load and speed simulating common freight routes of up to 896 miles. The energy harvested varies with operating conditions, and data is presented showing the effect of load and speed. Over a realistic route, the net energy harvested is more than double that needed to indefinitely power a Bluetooth Low Energy sensor. The critical design parameters are the ratio of open-circuit voltage to the temperature difference for the thermoelectric module, and the cold start voltage of the boost converter.

Satellite-Linked Remote Physiologic Monitoring During Simulated Rural Ground Ambulance and Rotor Wing Transports

Telemedicine and remote monitoring are rapidly gaining momentum in health care, including in-home and postdischarge monitoring. However, remote monitoring for telemedicine teams and receiving medical centers is yet to reach emergency medical services. When transporting a critically ill patient, continuous vital sign monitoring may be helpful to enhance receiving center collaboration and change care delivery before arrival when necessary. Our primary objective was to demonstrate successful transmission and reception of real-time physiologic summary data to a hospital base station during ambulance transport using a low-energy Bluetooth wireless wearable device linked to iridium satellite communications. We completed our proof-of-concept study on 2 simulated ground ambulance transports and 1 helicopter flight in rural areas surrounding Rochester, Minnesota. Each simulated transport used Mayo Clinic–developed wearable devices paired one-to-one with a physiologic communication kit. Electrocardiographic and photoplethysmographic waveforms were processed on the wearables every 5 minutes, with vital sign data generated and transmitted to an iridium satellite and relayed to a base station network–protected computer and mobile application with real-time display of summary and location. Data and geolocation were tracked in real time with a mobile application during the simulated transport, and summary data packets were saved on Mayo Clinic servers. During the 3 simulated rural transports, all (n=7; 100%) wearables successfully captured, recorded, and transmitted raw waveform physiologic signals. All devices transmitted successfully via the iridium satellite to the base station network–protected computer and mobile application. In all, 106 (69%) of 154 transmissions were successfully processed. Our project demonstrated successful remote monitoring of physiologic vital signs during transport in rural, low–cellular signal areas. The use of live remote monitoring should be explored to understand its utility in practice and outcomes.

A battery-less wireless implant for the continuous monitoring of vascular pressure, flow rate and temperature

Devices for monitoring blood haemodynamics can guide the perioperative management of patients with cardiovascular disease. Current technologies for this purpose are constrained by wired connections to external electronics, and wireless alternatives are restricted to monitoring of either blood pressure or blood flow. Here we report the design aspects and performance parameters of an integrated wireless sensor capable of implantation in the heart or in a blood vessel for simultaneous measurements of pressure, flow rate and temperature in real time. The sensor is controlled via long-range communication through a subcutaneously implanted and wirelessly powered Bluetooth Low Energy system-on-a-chip. The device can be delivered via a minimally invasive transcatheter procedure or it can be mounted on a passive medical device such as a stent, as we show for the case of the pulmonary artery in a pig model and the aorta and left ventricle in a sheep model, where the device performs comparably to clinical tools for monitoring of blood flow and pressure. Battery-less and wireless devices such as these that integrate capabilities for flow, pressure and temperature sensing offer the potential for continuous monitoring of blood haemodynamics in patients.

Multichannel Neighbor Discovery in Bluetooth Low Energy Networks: Modeling and Performance Analysis

Bluetooth Low Energy (BLE) has become one of the enabling wireless technologies to facilitate the Internet of Things. Neighbor discovery is critical in BLE communications. BLE uses multiple (three) channels in neighbor discovery. It is challenging to achieve low-latency and low-energy-consumption BLE neighbor discovery due to the lack of analytical models for multichannel neighbor discovery. In this paper, we study BLE multichannel neighbor discovery for two advertising modes specified by BLE: periodic deterministic advertising (PDA) and pseudo-random delay advertising (RDA). We build two generic models, BLE 3-Circle model and BLE 1-Circle model, for characterizing BLE multichannel neighbor discovery. For PDA mode, we present a necessary and sufficient condition for BLE multichannel neighbor discovery, and provide a guideline for parameter setting. With the guideline, we derive the expected discovery latency in closed form, and demonstrate that the expected discovery latency is very close to a theoretical lower bound. For RDA mode, we build an analytical model based on Markov chain to accurately compute the expected discovery latency. Simulation and experimental results show accuracy of our analytical works. Interestingly, our parameter setting guideline works well for both PDA and RDA mode.