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What is Bluetooth Low Energy (BLE)? How does BLE work?

What is Bluetooth Low Energy (BLE)? How does BLE work?

What is Bluetooth Low Energy, also known as BLE?

Contents

What is Bluetooth Low Energy (BLE)?

In 2011, bluetooth low energy (BLE) hit the market, and was marketed as ‘bluetooth 4.0’. BLE implements the same simple pairing modules, authentication protocols, encryption, and link security offered by standard bluetooth. This makes BLE devices just as easy to set up, and just as reliable as bluetooth devices. However, there are some important differences between BLE and bluetooth that we will discuss in this article.

How does Bluetooth Low Energy (BLE) technology work?

BLE works in the same 2.4 GHz industrial, scientific, and medical (ISM) band as standard bluetooth, and also uses different channels than standard bluetooth. BLE uses 40 2-MHz channels for transmitting data using gaussian frequency shift modulation (a method used for smoother transitions between data pulses), making frequency hopping produce less interference issues compared to standard bluetooth communications. 

Direct sequence spread spectrum is used in BLE technology to reduce interference caused by BLE signal transmissions. Standard bluetooth technologies use the method of frequency-hopping spread spectrum (FHSS) to transmit radio signals which produces significant interference compared to BLE.

Discovery of BLE devices

BLE devices are discovered through the broadcasting of advertising packets over 3 separate frequencies to reduce interference. A BLE device sends out a repetitive packet of information over one of three channels with random delays of up to 10 milliseconds. The repetition period between each packet of information is called the ‘advertising interval’. 

These packets of information can be discovered by other devices looking to connect with a BLE device. Devices looking to connect with BLE devices scan for BLE signals by opening up a ‘scan window’ and ‘scan intervals’ to find signals to connect with coming from BLE devices. Once a signal is discovered and paired with, both devices are considered to be connected.

What is the difference between BLE and Bluetooth?

Differences between BLE and bluetooth are split into 6 categories: power consumption, range, throughput, connection speed, number of connections, and cost. More practical differences are that BLE does not support the voice capabilities of standard bluetooth technology, and is generally more secure and robust than standard bluetooth. 

Power consumption

BLE uses less power than previous versions of bluetooth technologies while still operating over the same 2.4 GHz ISM band. BLE achieves this by constantly being in ‘sleep mode’ until a connection is initiated. This allows BLE devices to function significantly longer than bluetooth devices because BLE is not always consuming power from the devices battery. It is only consuming power when in use and when connections are initiated. Before BLE, bluetooth enabled devices constantly used power to support their bluetooth capabilities. 

The power consumption of BLE is so low that small BLE devices can function between 5-10 years on a small coin cell battery. This is because the actual connections made by BLE devices only last a few seconds when initiated, with a peak energy consumption of ~15 Ma and an average of 1 uA. To simplify understanding the differences in power consumption between BLE and bluetooth, remember BLE uses about 1/10 of the energy bluetooth devices use.

Range

The range of bluetooth is much greater than the range of BLE. This is because BLE is optimized for longevity and low power consumption. While bluetooth is optimized for throughput and range. If devices need a longer range to operate they should be using bluetooth, but if they need to operate for longer periods of time over shorter distances than BLE should be used.

Throughput

BLE excels at transmitting small and infrequent data packets using low amounts of power with low latency. While bluetooth excels at transferring large amounts of data continuously. The throughput for BLE devices is ~100-250 Kbps, and for bluetooth devices throughput is about ~2 Mbps. To put the differences in throughput into perspective, one megabit is equal to 1024 kilobits, and 2 Mbps is equal to 2000 Kbps. This makes the throughput of bluetooth devices about 10 times more than BLE devices.

Connection speed

Another difference between bluetooth and BLE is in connection times. Bluetooth connection times are ~100mS, while BLE connection times are only a few mS — making connections to BLE much faster than standard bluetooth devices.

Number of connections

BLE devices are able to connect with a larger number of other devices, or ‘slaves’, compared to standard bluetooth. BLE devices can vary in how many connections they are able to make with other devices depending on the memory built into them and how they are being implemented.

This is an important feature of BLE for uses in applications such as indoor location tracking systems and geofencing. Bluetooth is better at establishing a connection with a lower number of devices and sending more information over a wider area than BLE.

Cost

Bluetooth devices use slightly more complex protocols to function and require larger batteries for operation which makes them more expensive than BLE devices. However, bluetooth devices can use a wider range of batteries when compared to BLE devices, making sourcing batteries for bluetooth devices easier than sourcing batteries for BLE devices.

BLE devices are made for a narrower range of use cases than bluetooth devices making achieving greater economies of scale easier for BLE devices which drives down their cost.

What are Bluetooth Low Energy (BLE) Beacons?

BLE beacons are the hardware of BLE devices powering the transmission of broadcast signals. Beacons are the hardware responsible for enabling actions to be performed by technologies in proximity to a BLE beacon, such as smartphones, tablets, and other devices. BLE beacons allow a BLE device’s location and movement to be tracked. They are also what allows location-based actions to be triggered when a BLE device enters a certain area. BLE tracking is made possible through BLE beacons.

ble beacons

How is BLE technology used with beacons?

BLE beacons work as broadcasting devices that send information one way to receiving devices, and successful transmission often requires specific software installed on devices to interact with BLE beacons. Software requirements for devices interacting with BLE beacons is necessary to prevent interactions not desired by the owners of BLE devices.

Universally unique identifiers

BLE beacons use universally unique identifiers (UUID) that make their transmissions highly likely to not be the same as another BLE beacon. The chances of BLE beacons using the same UUID are extremely low, but it is possible. The use of UUID is what makes it possible to link and create information coming to and from specific BLE devices. The use of UUID is standardized by the Open Software Foundation (OSF) as part of the Distributed Computing Environment (DCE) software system developed in the 1990’s for standardizing software architectures.

BLE beacon protocols

There are several different BLE beacon protocols in use, including: iBeacon, AltBeacon, URIBeacon, and Eddystone. iBeacon is the BLE beacon protocol used by Apple, and is used to help simplify payments and offer in-store / on-site offers. AltBeacon is the open source alternative to iBeacon created by Radius Networks.

URIBeacon works differently than iBeacon and AltBeacon because it transmits a URL directly to BLE devices instead of an identifier signal. Eddystone beacons are the most robust and diverse BLE beacons, and they are the standard used by Google.

They can send additional information such as battery voltage, beacon temperature, beacon uptime, and number of information packets sent since last start up.

Similar technologies to BLE beacons

A similar technology to BLE beacons is near field communication (NFC). Many NFC applications overlap with BLE beacons. NFC can be passive or active, and many modern devices support both NFC and BLE beacons. For example, NFC is supported by Apple devices, but support is limited to payments only.

How does Bluetooth positioning work?

Bluetooth positioning determines the location of bluetooth enabled devices. It relies on the received signal strength (RSSI) measurements between bluetooth devices to estimate the distance between each device. For bluetooth positioning to work there needs to be multiple bluetooth devices communicating with each other to estimate the location of bluetooth devices. 

BLE positioning works through BLE beacons mounted on walls to determine the location of BLE compatible devices, such as mobile phones for BLE tracking tags. Due to the low power consumption of BLE beacons they are able to work for years using a single battery.

How accurate is Bluetooth Positioning?

Bluetooth positioning supports device location within about a meter. Bluetooth positioning systems can be made more accurate by adding the ability to determine the movement of bluetooth devices within an area. If movement can be accurately assessed, bluetooth positioning systems can become more accurate; up to centimeter level accuracy.  Detecting the movement of bluetooth devices relies on determining the Angle of Arrival (AoA) and/or Angle of Departure (AoD) of bluetooth signals. AoA works by a bluetooth tag broadcasting its location to a multi-antenna array receiver device capable of estimating the signals angle and direction. AoD works by multiple bluetooth beacons sending their location coordinates to bluetooth devices (such as cell phones) capable of estimating their relative location in relation to the location of surrounding beacons. AoD and AoA are made possible by bluetooth 5.1

What is the Range of Bluetooth Low Energy (BLE)?

The range of BLE devices depends on multiple factors. Range depends on the performance of BLE beacons and BLE enabled sensors operating within their surrounding environments. Areas with more interference from other signals and/or physical obstructions such as people, machines, and walls will have shorter ranges compared to operating in environments with no interference from physical obstructions or other signals. 

Under optimal conditions BLE can operate up to 100 meters, but in practice they operate best from 0-25 meters. The range of BLE is shorter than other radio frequency based location technologies such as Wi-Fi and ultra wide-band (UWB).

How is BLE different from other RF Technologies?

BLE possesses unique characteristics compared to other RF technologies. This makes BLE more suitable for specific uses based on budget, operating environment, and use case. The primary difference between BLE and other RF technologies, such as Wi-Fi and UWB, is that BLE uses very low power consumption.

Wi-Fi vs. BLE

Wi-Fi and BLE both operate using the 2.4 Ghz frequency range, are found on many commonly used devices, and are both used in indoor positioning systems. They both use RSSI to find the location of devices, people, and other assets. 

BLE has more hardware and software options for real world use because of its low power consumption and higher accuracy compared to Wi-Fi. Despite the benefits of BLE over Wi-Fi, many organizations still use Wi-Fi instead of BLE because less investment is required to implement an indoor location tracking system using Wi-Fi than BLE. 

Most organizations already have the Wi-Fi infrastructure to implement a Wi-Fi based location tracking system. For most organizations, implementing a BLE location tracking system involves purchasing additional infrastructure such as BLE beacons, sensors, and more. Another reason why organizations opt for Wi-Fi over BLE is because Wi-Fi enables communication capabilities over a larger range and for more data to be transmitted. 

Many organizations believe BLE is too limiting compared to Wi-Fi because of its cost, range, and data throughput limitations. 

UWB vs. BLE

BLE and UWB are very similar. They both offer low power and low cost solutions for location tracking. Where they differ is mainly with their accuracy. UWB is far more accurate than BLE. UWB takes highly precise location measurements using time-of-flight (ToF). ToF is the measurement of the time it takes for data transfer between UWB devices. From the time between signals between UWB devices their location can be precisely measured using UWB. BLE uses RSSI to determine the location of other BLE devices, but with varying degrees of accuracy based on the strength or weakness of signals between BLE beacons and sensors. 

Despite the accuracy advantages of UWB over BLE, many organizations will still opt for BLE because of the large amounts of options for different BLE beacons, tags, and sensors. UWB requires more specialized and expensive hardware to generate highly accurate location data. 

However, organizations that require highly precise and accurate location data should opt for UWB over BLE. UWB generates location data with an accuracy of less than 50 cm, and bluetooth location accuracy is measured in meters. The latency of UWB is also less than 1 millisecond compared to a latency of 2-5 seconds for BLE.

What are Bluetooth Low Energy (BLE) use cases?

BLE is used for many different applications, but are best suited for uses where other location tracking technologies are limited such as in indoor environments where GPS systems cannot accurately assess the locations of people, objects, and other assets. Satellite signals for tracking location get significant interference in indoor environments and their signals can become completely unavailable to GPS receivers that are indoors. 

The primary use case for BLE is for indoor positioning systems. Indoor positioning systems are implemented to track the location of people and assets, promote products, share information, and to help the navigation of people.

Asset tracking

BLE is useful for tracking the general locations of people, equipment, and goods within indoor environments. Many manufacturing and warehousing facilities use BLE to track assets within them. Each employee and machine can be tracked to improve productivity and prevent injuries / damages. BLE enables organizations to manage and monitor their assets and employees in dangerous areas, such as within mining operations or within hospital rooms during pandemics.

Production promotion

BLE is capable of promoting products to people with devices close to a certain location. Companies use BLE to send push notifications to their users mobile devices when in close proximity to their stores. Allowing businesses to run specific advertising and marketing campaigns to people in close proximity to locations where they can purchase products and services.

Sharing information

BLE enables sharing information to people at a certain location. BLE is used in museums, exhibitions, and tourist attractions to help promote the sharing of interesting and useful information to guests about points of interest (POI) within the immediate environment. Information sharing is done using the URIBeacon protocol for sending URL links directly to the devices of consumers.

Navigation

BLE is also used to help people find their desired destinations faster. This is generally enabled by people installing a specific mobile application to enable communication between their devices and surrounding BLE beacons in certain areas. These applications are commonly used for helping people get to the correct locations for catching busses, trains, and planes.

Specific applications of BLE for indoor positioning

BLE for indoor positioning systems (IPS) takes advantage of the low power, simplicity, and availability of BLE devices. This allows IPS using BLE to offer specific location services which include: item finding, real-time location tracking, point of interest information, and wayfinding.

Item finding

BLE enabled item finding allows people to find BLE devices within indoor environments such as rooms, homes, workshops, and offices. Items must be equipped with a small BLE transmission device that is paired with a mobile device, or other device that can track the item of interest.

Point of interest

Point of interest works in a similar fashion to item finding, but is related to the proximity of BLE devices to BLE beacons. BLE beacons are able to send information about a location or object to devices equipped with communication software enabling a connection to the BLE beacons of interest. For example, people visiting a museum would receive information about specific areas within the museum as they visit each section of the museum.

Real-time location

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Wayfinding

Wayfinding is the most common application of BLE for indoor positioning. BLE beacons and devices can communicate with each other to direct people to appropriate destinations within large and/or complex facilities. It can help people reach their final destinations quickly by suggesting the shortest path to take.

What industries use BLE technology?

Many industries use BLE tracking and other technologies to track the positions and send information to and from people and other assets. Industries commonly using BLE technology include: security, manufacturing, healthcare, travel, advertising, entertainment, and retail.

Security

BLE enhances the security of organizations by automating and monitoring a facility’s entranceways, access points, hazardous area, and data systems. BLE beacons can also enable the monitoring of environmental conditions such as humidity, light, and temperature.

Manufacturing

BLE tracking technology is capable of monitoring the raw materials, tools, products, and staff working in the manufacturing industry. It can be used to monitor asset-employee associations and help organize the logistics associated with incoming shipments, delivering, and tracking of containers and vehicles.

Education

BLE positioning technology enables education organizations to automate their student attendance, manage access to their networks, and monitor the use of devices owned by the facility.

Healthcare

The healthcare industry uses BLE tracking to streamline the monitoring of patients, staff, and assets. They allow the location of all BLE tracking tags to be known at all times so patients, staff, and assets can be managed effectively in response to situations that arise within healthcare facilities.

Travel

The travel industry commonly uses BLE positioning for ticket sales, passenger registration, passenger wayfinding, and issuance of travel advisories. BLE for real-time location tracking is often used for automating passenger registrations and check-ins, monitoring the number of visitors (regular and unique), and timestamping the location of employees.

Advertising

Advertisers use BLE positioning to locate consumers in specific areas to send contextual advertisements to. These advertisements are contextual based on known data about the consumer they are targeting such as their online purchase histories and physical location to stores and/or displays.

Entertainment

The entertainment industry implements BLE positioning to help brands sell to more consumers through the hyper-local advertisement of their products and services to people at an entertainment event.

BLE is also used to improve the customer experience by allowing visitors attending an event to receive information about the event directly to their mobile devices, reducing the need for staff and reliance on brochures and maps.

Retail

BLE positioning is used to create a connection between a customer’s online activities and their physical presence in stores.

Stores are able to push specific offers and notifications to their customers based on their past online and in person purchase histories.

Conclusion

BLE is used for many different applications,especially for accurately finding the locations of people, objects, and other assets. The main advantage of BLE is its low power consumption, but it also brings a narrow cover range. BLE’s narrow range makes it a very cost-effective technology.

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