Bluetooth Low Energy: The Ultimate Guide on BLE From CTO

To start with, Bluetooth was initiated as a short-range technology to replace nodes and wires as a connection method. According to Statista the current number of shipped Bluetooth devices isn’t only presented in billions but is also growing continuously from year to year. Thus proving that the relevance of Bluetooth technology isn’t going to leave global markets in near future.

The Advantages of BLE

• Accessibility. Nowadays almost every phone has an integrated BLE module making features of wireless connection wide open for every smartphone-like device owner. Besides, Bluetooth Low Energy technology is compatible with integration in devices that don’t require any apps for maintaining quality connections with various products. Hence, its accessibility is not only defined by being integrated into phones and tablets.
• Low power requirements. Along with transmitting data in small amounts, there’s another thing that lets BLE be the lowest power consumer amongst the candidates. Key optimization in conserving power is achieved by keeping the signal transmission off whenever it’s not used.
• Low elements cost. Among the BLE analogues the original technology boasts with low prices for chipsets, modules, and other components. Thus granting a cost effective option for the development to surpass any competitor existing.
• Free specification documents. The most notable advantage of Bluetooth Low Energy is that any specification document you may need can be easily found and downloaded from the official Bluetooth website. While some technologies require considerable payment for access to the documentation, BLE shows you that it is free to use for everyone.

The Limitations of BLE

• Limited range. There are several factors that lead to BLE’s short distance. First of all, the BLE frequency spectrum is vulnerable to the obstacles between the connected devices, making it yet impossible to implement connections exceeding 100 meters. And the other factor that complicates the long-range connections includes all the issues with a BLE antenna such as device orientation and physical location.
• Low data rate. Bluetooth Low Energy can’t be used to transfer data of more than Bluetooth basic rate of 1 or 2 Mbps as, for example, cellular and wifi technologies can handle. One of the causes is the requirement of Bluetooth Low Energy specification for a 150 ms signal gap between the packet transmission along with the transmission power being dependent on the connection range.

Are BLE and Classic Bluetooth Devices Compatible?

Despite sharing the brand and specifications, Classic Bluetooth and low power Bluetooth aren’t compatible, a consideration important in the prototyping steps in IoT. It means that it’s impossible to connect devices directly.

Is there a Way to Make Classic Bluetooth and BLE Compatible?

To avoid Bluetooth LE vs Classic compatibility issues many smartphone-like gadgets tend to implement both of these technologies thus enabling communication with every side. Smartphones with such Bluetooth chipsets are called Dual Mode Bluetooth devices and are able to work with both Bluetooth Low Energy and Bluetooth Classic. According to the Bluetooth SIG report, each key platform device supports BLE Bluetooth and Classic Bluetooth.

Which One is Better: BLE or Bluetooth Classic?

Based on the experience of our CTO, it’s impossible to say which of the technologies is “better” or “worse” in general. The answer depends on your needs: whether you need to have a continuous data transfer, transmit large data packets, have the possibility to frequently recharge your device, etc.

Let’s see some examples of goals and determine the technology that fits better in distinct cases:

What is a Bluetooth LE Device Network?

Let’s talk about the main use cases of BLE enabled devices.

What are the Analogues of BLE?

Just like any other technology in today’s vast tech world, there will always be competitors. A competitive factor not only opens up a wider set of options to choose from but also lets the technologies prosper and evolve more among the analogues.

Competitive technologies:

• Z-Wave. A wireless protocol that’s represented as a mesh network with LE radio waves primarily used for home automation.
• ZigBee. A specification for creating personal area networks with the use of low-power radios. Presented as a mesh network, it’s responsible for low-power wireless connections in home automation and healthcare data management.
• Thread. A low-power mesh networking protocol based on IPV6 for Internet of Things product development. The main focus of this technology is providing outstanding security standards and being future-proof.

What is Bluetooth Low Energy Architecture?

As stated by Oleksii, the BLE architecture is the network and organization of components within the BLE protocol stack or protocol suite. It consists of three main layers.

1. The application layer. It serves as the direct interface with the user and encompasses the application logic, user interface, and overall application architecture.

2. The host layer. It includes multiple protocols and profiles:

• Attribute Protocol establishes rules for accessing data, and defining attributes' structure and operations.
• Security Manager Protocol ensures secure device communication and addresses privacy. It validates and performs authentication during the pairing process. Additionally, it can deter detrimental tracking of a device’s Bluetooth address by concealing it.
• Logical Link Controller and Adaptation Protocol (L2CAP) acts as a protocol converter and handles standard BLE packet fragmentation.
• Generic Access Profile (GAP) manages BLE device communication, covering roles, advertising, and connection establishment.
• Generic Attribute Profile (GATT) facilitates attribute data transfer between devices, with a client-server model for read/write operations.

3. The controller layer. The physical component of BLE firmware, the controller decodes signals and operates on the 2.4GHz bandwidth, dividing it into 40 channels for data transmission and advertising. The controller layer also comprises the physical and link layers, which manage how devices communicate.

• The physical layer denotes the radio hardware utilized for communication and data modulation/demodulation.
• The link layer serves as an interface between the physical layer and higher levels, interacting with the radio through an intermediary level known as the HCI (Host Controller Interface) layer. It handles radio state management and ensures adherence to the timing standards specified by Low Energy Bluetooth devices.

Are BLE Versions Backward Compatible?

Yes, Bluetooth Low Energy versions are backward compatible with each other. However, the features that were released in the newest versions won’t be supported by the older ones.

As an example, a BLE device with a Bluetooth 4.1 can easily be connected to a BLE device with Bluetooth 5.0, yet without access to the newest features of the 5-th version.

Can BLE Products Stream Audio?

Before the release of the Bluetooth 5.2 update, Bluetooth LE devices didn’t support audio devices. With the use of custom implementations, there was a way to make audio streaming possible, however, it was never about achieving a good quality sound. After Bluetooth 5.2, audio transmitting finally became possible with many upgrades and specifications awaiting in the future.

Protocols such as Bluetooth and ANT are pivotal in supporting diverse use cases, including real-time audio streaming.

How to Power BLE devices?

Bluetooth Low Energy is a technology for maintaining faster connections with low power consumption. It's quite typical for a BLE device to operate for a year on a single battery, which showcases how IoT helps in manufacturing by reducing energy consumption and extending device lifecycles. Still, there’re various sources to power such products, underscoring the need for developers to understand how to build companion apps with high power efficiency, especially when developing a health and fitness app that relies on real-time data from BLE sensors. The most common power sources for BLE’s battery life are:

• Coin Cell Batteries
• Lithium Batteries
• Rechargeable Lithium Batteries
• Alkaline Batteries

Which makes it crucial to understand how to build battery management software to maximize performance.

What Certifications are Required for BLE Products?

Considering that Bluetooth Low Energy radios in fact are Radio Frequency (RF) transceivers — the needed certifications depend on the country where the device is going to be used. Besides the certifications, it’s also required to get an End Product Listing with the Bluetooth SIG, which is a critical step in the Bluetooth Low Energy development process. Some examples:

• European Region — CE certification
• Canada — IC certification
• The US — FCC certification

Is an App a Necessity for BLE?

Communicating and managing Bluetooth Low Energy products, such as those utilized in IoT in smart farming, is often maintained via a specialized app for iPhones or Android devices. Thus, an app is the most common way for managing BLE connection requests, and a BLE app development company can ensure a seamless connection experience, however, connecting devices directly is also practically possible. For example, Web BLE implementation allows for direct interactions with BLE devices through web browsers. We at Stormotion experienced the development of a heart-rate sensor with a direct connection to an exercise machine.

How Many Devices Can Be Connected to BLE Simultaneously?

Bluetooth Low Energy protocol is based on a Master (Central) and Slave topology, a Master can create a connection with multiple peripherals simultaneously as well as be the Slave and the Master at the same time. The peripheral device transmits timed advertising packets, while the central device scans for and utilizes these data to locate the peripheral device. A practical limit for the Central device — is supporting up to 20 peripherals connected.

However, the practical number stated before only shows the BLE capabilities in general, but this limit may be different for some cases. It depends on the application-specific aspects that define the number of simultaneous connections in particular cases. Such aspects are primarily:

• the limits set by the physical layer (the controller itself);
• limitations of the host OS.

Experimentally it was determined that a Samsung Galaxy S9 as a BLE Central can support up to 8 simultaneously connected devices. While the iPhone 8, for example, managed to connect up to 10 such products.

According to Microsoft Q&A, when it comes to connecting Bluetooth Low Energy to Windows it works as follows:

1. BLE devices in connections have three different activity statuses: “paired”, “connected” and “transmitting”. A device can have one, two or three active statuses at the same time. For example, it can be paired and connected but not transmitting or can simultaneously be paired connected and transmitting.
2. The devices in terms of communication can be hosts and clients. For example, speaking about connecting wireless peripheral devices to a PC, the first ones act as clients and the PC itself represents the host side.
3. Host devices are able to support up to 7 products with a “connected” status and as many as needed “paired” devices.
4. Client devices play a peripheral role and support only 1 connection and up to 5 “paired” devices.

What is an iBeacon?

iBeacon is an Apple protocol based on BLE proximity sensing that possesses a set of features similar to a Bluetooth LE protocol stack.

What is the Difference Between a BLE Beacon and an iBeacon?

Practically, to send information about the distance between connected products to a device, iOS delivers the actual calculated distance, while Bluetooth Low Energy relies on the RSSI (Received Signal Strength Indicator). Thus, in an iOS case, the estimated distance won’t depend on the device manufacturers and will be equal regardless of the device version.

How Do BLE Beacons Work?

Let’s introduce ourselves to a Beacon world step-by-step:

1. There is a small device called “Beacon” that is constantly transmitting radio signals.
2. Devices nearby (smartphones, tablets, etc.) supported by Bluetooth Low Energy detect the transferred signal.
3. The signal gives your device its ID number, saying “Here I am!”.
4. Your device sends the ID it got earlier to the cloud server.
5. The server processes the given ID and determines what action lays behind the assigned number and responds according to the scenario.
6. The result could be any action pre-programmed before!

What Security Protocols Should Have BLE Beacons?

Two popular types of Beacon attacks can affect your mobile product:

• Beacon Spoofing. The attacker detects the Beacon ID of your device and creates a clone that behaves the same. The application of such a technique is quite obvious. The attacker can place the duplicate in other places, fooling your mobile app and user.
• Beacon Hijacking. The attacker detects the Beacon ID of the entire Beacon network you've invested resources into. This allows them to build another application, even a competitor, relying on the same Beacons.

Oleksii explains that the effective solution against these attacks relies on replacing the real Beacon ID with a temporary replacement called Secure UUID. The exchange happens periodically through an algorithm known only by the Beacon and the server.

Even if the attacker captures a temporary identifier, it can't be used because it’ll expire soon. The algorithm shouldn't be stored in the mobile application because it can be reverse-engineered. This means the mobile application has to communicate with the server to exchange the temporary identifier for a real one.

This solution requires a constant internet connection. In other words, even if your mobile app caches content for offline usage, Beacon-related features will still require internet connectivity. You can make the exchange period longer or allow the application to cache several future identifiers, but these attempts to support offline capabilities come with lower security.

BLE Beacon Use Cases

Beacons are quite useful things that can serve as an informational source or even attract potential customers. Here are some examples of how beacons are used in the modern world:

• In museums and galleries beacons serve as an extended information source. While you're standing next to a famous painting, your device catches a signal from the closest beacon and, if you grant location permission, opens a page devoted to the history of the artist and their creation.
• In retail beacons often serve as an advertising device, notifying about the most interesting deals and discounts. While passing by a store your device catches the signal of a shop’s beacon and transfers you to a page with the newest collections and available disсounts. Moreover, shopping malls use beacons to offer customers GPS-like indoor navigation.
• In educational facilities beacons also serve as a notificator about the upcoming events, conferences, holidays, etc. Once again your device receives a signal with a pre-programmed announcement and grants access to a page with the approaching educational activities listed in one place.

Platoon Fit

Platoon Fit is a platform where any user may find various progressive exercises for managing indoor workouts. Along with providing exercise guides, the company pays special attention to video content.

Talking about Bluetooth Low Energy device, our task was to build an MVP that would support fitness tracking devices integration. More specifically, we needed to set up a convenient data transfer between connected heart rate sensors with the Platoon Fit application.

With the integration of BLE compatibility protocols to the project, we managed to achieve the high-level data transaction system only in 4 weeks of testing and prototyping.

SportPlus

SportPlus is another great specimen on Stormotion’s project showcase. The company produces and sells various unique sports equipment for making their customers’ fitness experience effective. Our task was to design an application that would support every type of exercise machinery they offer.

However, the solution for this case was a challenging one to develop. The challenge lies in the fact that nearly every sports machine the company offers necessitates the use of distinct protocols for exchanged data, which leads us to the main problem. To build a proper communication between an application and the equipment we need to take every possible protocol into account.

With the strategy we created, we managed to access the data flow between another functioning app and the specific machine they offer. Thanks to this decision, we determined the order and format required for sending and receiving different bytes of information in each particular case. After the experimental part, we succeeded in supporting every possible connection for a complete data collection and data exchange system, regardless of the required machinery protocol.