Survey of Bluetooth Indoor Localisation

Recent research provides a detailed survey on Bluetooth indoor localisation. The paper underscores the importance of indoor localisation and the unique challenges it presents, such as the inability of GPS to function indoors.

There’s an overview of the types of localisation methods, including triangulation, scene analysis and proximity, as well as the metrics used in these systems. The main localisation techniques discussed are RSSI (Received Signal Strength Indicator), CSI (Channel State Information), fingerprinting and other methods like Angle of Arrival (AoA) and Time of Flight (ToF). RSSI is widely used in Bluetooth localisation but suffers from poorer accuracy due to environmental factors. In contrast, CSI is rarely used due to protocol limitations. Fingerprinting is sometimes employed, involving the pre-collection of measured signal strengths to create a database for location matching.

The survey identifies issues affecting Bluetooth indoor localisation systems, such as accuracy, latency, coverage range, cost and security. Accuracy can be problematic in complex indoor environments, which introduce obstacles and multipath effects that negatively impact signal transmission and reception. The range of coverage is crucial, especially in large indoor spaces where fewer reference nodes are preferred. Cost considerations include both equipment and setup costs, and security issues arise due to the need to protect location data within personal networks.

The study summarises various existing approaches to Bluetooth indoor localisation, categorising them based on their robustness to environmental changes. In discussing RSSI versus fingerprinting, the survey notes that RSSI-based approaches are prevalent due to their simplicity and widespread use. Fingerprinting, on the other hand, involves creating a detailed database of data, which can provide more accurate localisation but requires substantial pre-processing and regular re-calibration to remain effective. Fingerprinting is susceptible to dynamic changes in the environment, making it less competitive in typically fluctuating conditions such as changes in room layout or occupancy.

GATT Connections and Battery Life

Our battery use power testing uncovered some cases where the battery current use during advertising was such that the battery would last longer than manufacturer specification. What was going on?

After contacting the manufacturers, it turned out that some of them include a degree of configuration activity in their battery life estimates. If you only measure the current during advertising then you haven’t taken into account the extra current used during configuration. Configuration via manufacturer apps connects, rather than just listens, to the beacon via Bluetooth GATT. GATT connections consume significantly more power. For one off configuration this will be negligible but if you are in the habit of repeatedly changing the beacon configuration then the battery life will be impacted.

The same goes for platforms/apps that periodically connect to beacons to read, change or monitor beacon parameters. The battery won’t last as long. It’s also for this reason, it’s preferable to read sensor beacon sensor data in advertising data rather than via GATT when this is supported by the beacon and your scenario can cope will less frequently reported data.

Balancing Bluetooth Throughput and Reliability in Interference-Rich Environments

There’s an interesting new paper titled Modeling the Trade-off between Throughput and Reliability in a Bluetooth Low Energy Connection that provides a comprehensive analysis of the performance of Bluetooth Low Energy (BLE) communication in terms of throughput and reliability under various interference conditions.

The primary objective of the study was to develop and validate mathematical models that predict the throughput and reliability of BLE connections under interference.

Two models were developed, a Throughput Model using a Markov chain approach to predict the throughput of BLE connections under interference, and a Reliability Model that quantified the reliability of BLE connections by considering various transmission parameters and interference levels.

The throughput model was validated through extensive practical experiments under different interference scenarios. The experiments involved varying parameters such as packet length, number of packets, and connection intervals. The results showed a close match between the theoretical predictions and the experimental data, highlighting the accuracy of the models.

As might be expected, the study found that the interference level in the environment significantly affects both throughput and reliability. Higher interference levels (higher BER) reduce both metrics.

There is a non-linear relationship between payload size and throughput. While larger payload sizes can increase throughput in low-interference environments, they significantly reduce reliability and throughput in high-interference conditions.

Increasing the connection interval improves energy efficiency but reduces throughput without affecting reliability. This suggests that connection interval adjustments can optimise energy usage without compromising communication reliability.

Bluetooth devices should be configured based on the specific interference environment they will operate in. For instance, smaller payload sizes are preferable in high-interference environments to maintain reliability.

De-risking Bluetooth Projects

Many projects encounter insurmountable problems that ought to have been identified before the initiation phase. For example, some make commitments to specific hardware, which can significantly impede future development or result in large unexpected costs.

This lack of foresight and planning, referred to as ‘unknown unknowns’, can lead to project failure or necessitate unwelcome changes in course. Savvy founders, on the other hand, seek advice from experts to lessen the risk of being blindsided.

Another common problem is compatibility issues can occur between various manufacturers or versions. This discrepancy can give rise to unforeseen development challenges or affect user experience post-launch. Another issue is the achievable range of Bluetooth that can be heavily influenced by real-world conditions. Elements such as walls, the presence of other wireless devices and even atmospheric conditions can significantly limit Bluetooth’s effective range, potentially undermining the overall functionality of your project.

Although Bluetooth is praised for its energy efficiency, the actual power consumption can substantially deviate based on factors such as signal strength, data rate and connection interval. Misunderstanding or failing to anticipate these factors can lead to unanticipated issues with battery life in the final product.

A preliminary study can help avert costly and humiliating errors. At BeaconZone, we evaluate the feasibility of your project and provide guidance on both software and hardware options. We are here to answer your queries, highlight potential barriers and bring to light issues you may have overlooked.

By choosing not to go it alone, you can avoid mistakes that would otherwise occur. You’ll gain insight into any pragmatic decisions that may need to be taken. We can provide accurate cost and time estimates for implementation, ensuring that you purchase the most suitable hardware.

Our services also help to guard against getting locked into platforms with uncertain future costs and risks. Learning from the anonymous mistakes of our past clients can provide you with valuable insights. Moreover, we can expediently integrate Bluetooth knowledge into your organisation, giving you a head start on future developments.

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Using Covert Channels with iBeacon

A new study Implementation and Analysis of Covert Channel Using iBeacon (PDF) explores the creation and analysis of covert communication channels using iBeacon, which is based on Bluetooth Low Energy (BLE). Covert channels are methods used to transmit information secretly, bypassing normal security measures.

The authors introduce two types of covert channels: one that uses the payload of the iBeacon broadcast messages and another that employs the broadcasting intervals. The payload-based covert channel modifies the UUID, Major, Minor, and TX power fields of the iBeacon packets to transmit covert messages. This method achieved a maximum throughput of 911,600 Bytes per second (Bps) with a Packet Delivery Rate (PDR) consistently above 75%, indicating its efficiency in transmitting substantial data covertly.

The interval-based covert channel, on the other hand, encodes messages in the time intervals between consecutive iBeacon broadcasts. Although this method provides higher concealment compared to payload-based channels, it has a lower channel capacity and can cause transmission delays.

The experimental setup involved using Raspberry Pi devices to simulate the transmission and reception of iBeacon packets, where various advertising intervals were tested. The findings highlighted that shorter advertising intervals resulted in higher throughput, with the best performance observed in the 100–200 ms range.

The study concludes by emphasising the potential for significant data transmission through BLE beacons and suggests future research to explore countermeasures against such covert channels.

iBeacon vs Beacon: Understanding the Difference

The term ‘Beacon’ is a generic name for all types of devices that use standard Bluetooth to transmit signals. Among these, iBeacon is the most popular and widely recognised.

Beacons: The Broad Category

Beacons are small, wireless transmitters that use Bluetooth Low Energy (BLE) technology to send signals to nearby devices. These signals can trigger actions, such as sending notifications, providing navigation or tracking assets. The technology is simple yet powerful, enabling a myriad of applications across various industries, from retail to healthcare.

The term ‘Beacon’ encompasses a variety of beacon types, each with its unique specifications and use cases. These include Eddystone, AltBeacon, and, of course, iBeacon. Despite their differences, all beacons share the fundamental ability to transmit data using Bluetooth, making them interoperable with any Bluetooth-enabled device that scans for such signals.

iBeacon: Apple’s Contribution to Beacon Technology

Among the different types of beacons, iBeacon is perhaps the most well-known. It’s important to note that while the iBeacon data format was developed by Apple, it can be detected by any device that has Bluetooth scanning capabilities, not just Apple products.

The iBeacon protocol defines a specific data format for Bluetooth advertising. This format includes three main components:

  • UUID (Universally Unique Identifier): A 128-bit value that uniquely identifies the beacon or a group of beacons.
  • Major Value: A 16-bit integer used to group related beacons. For instance, all beacons in a specific retail store might share the same Major value.
  • Minor Value: Another 16-bit integer that allows for more granular identification within a group. This could, for example, differentiate individual beacons within a retail store.

Other Types of Beacons

While iBeacon is the most prominent, several other beacon technologies are worth mentioning:

  • Eddystone: Developed by Google, Eddystone is an open beacon format that supports multiple data frame types. This flexibility allows it to broadcast URLs, telemetry data and other forms of information, making it versatile for various applications.
  • AltBeacon: Created by Radius Networks, AltBeacon is an open and interoperable beacon standard. It aims to provide a flexible alternative to proprietary beacon formats, ensuring compatibility across different platforms and devices.

Inside the iBeacon Data Advertising

The iBeacon Bluetooth packet structure includes the following fields:

  • Preamble: A series of bytes that mark the beginning of the transmission.
  • Access Address: A 32-bit field that identifies the packet as a BLE advertisement.
  • PDU (Protocol Data Unit): Contains the actual iBeacon data, including the UUID, Major, and Minor values.
  • CRC (Cyclic Redundancy Check): Ensures data integrity by checking for errors in the received data.

The brevity of this format allows iBeacons, in fact all beacons, to operate effectively with minimal power consumption, making them suitable for prolonged use in various environments.

Enhancing Indoor Localisation for Ambient Assisted Living

New research Simplified Indoor Localisation Using Bluetooth Beacons and Received Signal Strength (RSSI) Fingerprinting with Smartwatch, introduces an innovative system for indoor localisation using Bluetooth Low Energy beacons and smartwatches, aimed at simplifying the process for users. This system is designed to detect a user’s location within specific areas like rooms within a house, rather than providing exact coordinates, with a particular focus on applications in ambient assisted living, especially for the elderly.

The study presents the methodology, implementation, and evaluation of the system, highlighting its practicality for real-world applications. The system demonstrated high accuracy, achieving 92.1% in environments with five rooms and 85.9% with three rooms, showcasing its effectiveness. The setup process is streamlined to reduce the number of reference points and employs a straightforward nearest neighbour algorithm, which simplifies the use and maintenance for users who may not have extensive technical skills.

The use of common and low-cost hardware components, such as Raspberry Pi for beacons and commercial smartwatches, helps keep the system affordable and simple to manage. Calibration is quick and efficient, which is ideal for residential settings. Despite its current effectiveness, the research suggests there is room for improvement. Future enhancements might include the adoption of multiple reference points per region to refine accuracy, particularly in transitional spaces between rooms.

This system offers a robust solution for indoor localisation with significant implications for healthcare, particularly aiding elderly individuals to live independently while ensuring their safety and mobility within their homes.

Beacons on Cruise Ships

Carnival Cruises is using Ocean Medallion™, a beacon that allows you to board the ship, open your room door, navigate the ship, find your family and friends onboard, make reservations and order and pay for food and drinks.

This is a significant and well thought out rollout for many reasons:

  • Large undertaking – In order to use the system, each ship is fitted with 75 miles (121km) of cables, more than 7,000 sensors and 4,000 digital screens.
  • Mass market promotion – it has even been mentioned on the BBC.
  • First large rollout to use beacons with NFC – As we previously mentioned, NFC can be used for, closer, security-related activities such as payment.
  • Used as a USP – The How It Works web page is using the added convenience as a unique selling point.
  • No battery life problems – The beacon only has to transmit and last as long as the holiday.
  • User Experience aware – The beacon has been designed to look like jewellery to gain acceptance. It’s engraved with the customer’s name and can be worn as a necklace, clip or on a keychain.

The clever part is that the gains aren’t just for Carnival cruise guests. The new system will also allow more personal location information to be gathered that can be used offer better targeted promotions and hence help increase revenue per customer.

Indoor Navigation for Environments with Repetitive Structures

New research looks into indoor navigation systems specifically designed for environments with repetitive structures, such as cruise ships, using Bluetooth low-energy (BLE) beacons without relying on GPS. The system incorporates a mobile application that uses these beacons to guide users accurately within buildings. The system optimises navigation through the use of pre-calculated routes, which minimises data storage requirements and enhances the application’s energy efficiency.

It system includes a sophisticated user interface that displays the route and updates navigation in real-time based on user movement and beacon signal reception. The implementation faced several challenges, particularly related to the synchronisation and real-time processing of beacon signals, which were addressed by optimising the beacon scanning process and the communication between system components.

The study lays the groundwork for future exploration and deployment of indoor navigation systems that leverage repetitive architectural features for enhanced navigation efficiency.

Minew’s New MWC01 and MBT02 Repeater Beacons

Minew has recently launched two new beacon models, the MWC01 and MBT02, a new type of product that is a repeater. These repeaters are designed to scan for beacons and re-transmit the strongest signal, providing a new approach to locating, and a way of extending Bluetooth communication.

The intended use of these repeaters isn’t entirely clear from the Minew website, so here’s an explanation of how they work and their benefits.

Traditional Beacon Systems

In a conventional setup, multiple gateways detect beacons within an area and server-side software uses trilateration to calculate the position of an asset or person. This method often lacks accuracy due to the fluctuating and imprecise nature of Received Signal Strength Indicator (RSSI) measurements.

Bluetooth Direction Finding

Bluetooth Direction Finding was introduced to improve accuracy. It uses the angle of arrival of Bluetooth signals, requiring complex software and specialised hardware. While very effective, this method can be complicated, time consuming and expensive to implement.

The Role of Repeaters

Minew’s new repeaters offer a middle ground between traditional RSSI-based systems and advanced Bluetooth direction finding. Here’s how they work.

Extra fixed Bluetooth beacons are placed throughout the area. The repeaters, attached to moving assets, detect the beacons and send the strongest signal to a single gateway. This reduces the number of gateways needed and allows for the strategic placement of beacons to enhance accuracy where necessary. It is a simpler and more cost-effective solution than Direction Finding implementations.

Additional Uses

Repeater beacons can also function as fixed repeaters to extend the range of a beacon where it’s insufficient. This is particularly useful for sensing and IoT applications, providing extra range and reliability.

Contact Us

Interested in integrating Minew’s repeater beacons into your solutions? Contact us for more information.