Bluetooth 5.2 is the most recent version of the technology, and although it is not generally accessible yet due to delays in consumer models as well as support due to that pesky Covid-19 epidemic, the possibilities it offers are already very intriguing.

One of the most important things to highlight is Low Energy power management, which is the first of these major points. The low-energy Bluetooth 4 standard was released, however, it was not sophisticated enough to be utilized with the majority of practical applications, such as the streaming of music. As a result, low-energy activities were actually only utilized for smaller-scale processes, such as those associated with fitness watches or other devices of this kind.

Bluetooth 5.2 allows for the transmission of greater quantities of information across lower bandwidths and at lower power levels for the first time. Essentially, this is accomplished via the use of the new LC3 codec, which results in information being compressed more on the input side while being decompressed considerably more effectively on the output side of the transmission. This is excellent news for people who want high-quality Bluetooth audio since the fidelity of the music will be much improved. Because of the efficiency and speed of the decode on the other side, the audio information may be compressed considerably smaller – saving both time and energy – without sacrificing any quality.

It also has an enhanced attribute protocol, which enables concurrent transactions between two Bluetooth devices to take place at the same time in version 5.2. For example, if you have several applications running on your smartphone that are all utilizing the same Bluetooth device, this might be helpful. They will be able to function simultaneously instead of one being blocked while the others are running.

Finally, the usage of Isochronous Channels, which is probably the most intriguing addition of version 5.2, is discussed. This extends the functionality of the Dual Audio feature even further, enabling several Bluetooth devices to be connected to a single source. When using your wireless headphones at home, instead of having to switch between your laptop, phone, and television, your headphones may be linked to all of them at the same time and transition between them instantly and smoothly.

Moreover, this is very interesting in terms of the broadcasting possibilities that are available. Depending on how widespread the use of Bluetooth 5.2 becomes, it may be possible to walk into a crowded bar, spot something interesting on the television, and then tune into that stream using your Bluetooth headphones – or even that everyone watching the same program could access different language streams. This possibility, apart from being convenient, portends a revolution in hearing aid technology, as the hearing impaired may be able to beam whatever they are listening to into their earpieces with relative ease in the near future. What you’ve just read is very thrilling.

What’s New in Bluetooth version 5.2

The Bluetooth Special Interest Group (SIG) released the newest version of Bluetooth, version 5.2, a few months ago at CES 2020 (in January 2020). This statement was made at the same time as the introduction of the next generation of Bluetooth audio, which has been designated as LE Audio (Low Energy Audio).

The most significant modification made in version 5.2 is the addition of a new feature known as Isochronous Channels (ISOC). The ISOC provides the groundwork for the deployment of LE Audio in Bluetooth Low Energy (BLE) devices that support Bluetooth 5.2 or later.

However, ISOC is not the only new feature that has been included in this most recent release. In today’s article, we’ll take a look at three significant improvements that were added to LE Audio in version 5.2, two of which are not directly connected to the software.

The three characteristics are as follows:

  • Isochronous Channels (ISOC)
  • LE Power Control (LEPC)
  • Enhanced Attribute Protocol (EATT)

LE Audio is the next generation of Bluetooth audio technology

Before we get into the specifics of the Isochronous Channels feature, let’s take a moment to discuss LE Audio and what it means for us as users and developers.

Bluetooth technology has established itself as the de facto standard for wireless music transmission since its inception. Bluetooth audio products, such as wireless speakers and car infotainment systems, as well as wireless headphones and earbuds, are becoming more common these days. As a matter of fact, streaming music apps are the most popular use for Bluetooth.

In the past, the Bluetooth radio that was utilized for these applications was the original Bluetooth radio, also known as Bluetooth Classic or BR/EDR (Basic Rate/Enhanced Data Rate), which has been in use since the specification’s version 1.0. The new LE Audio, on the other hand, was powered by Bluetooth Low Energy technology (BLE).

LE Audio not only achieves the same capabilities and standards as Bluetooth Classic, but it also adds a few new functions and enhances the functionality of current ones.

1. Isochronous Channels (ISOC)

The meaning of the term “Isochronous” is “occurring at the same time,” which can be found by searching for “isochronous” in the dictionary. In the context of Bluetooth Low Energy, this implies enabling (1) time-sensitive data transfers and (2) synchronized display of these data streams across many receivers at the same time. As previously stated, this new functionality serves as the basis for the LE Audio product line.

A new Physical channel, the Isochronous Physical Channel (ISOC), is introduced in Bluetooth Low Energy (BLE). It may be utilized on any of the LE PHYs, including the one-meter PHY, the two-meter PHY, and the LE Coded PHY (which includes both s=2 and s=8 configurations).

Communication that is geared toward connections and communication that is not aimed toward connections

Both connection-oriented and connectionless communication are supported by the ISOC. When it comes to Bluetooth Low Energy nomenclature, this implies that both connections and broadcasts are supported.

Each stream in a connection is referred to as a Connected Isochronous Stream in the connection terminology (CIS). When two or more CISes must be synchronized, such as those transmitted to left and right earphones, they are set to be part of a single group, known as a Connected Isochronous Group (CIG).

It is essential to exchange timing reference data across streams that are members of the same CIG in order to provide synchronized stream rendering on various receivers. Data transmission is possible in both directions with CIGs, which is useful in applications such as earbuds with microphones and for transmitting control data to the source device.

2. LE Power Control (LEPC)

When the initial transmit power of a transmitter is known to the receiver, the received signal strength indicator (RSSI) may be used to determine the distance between the receiver and the transmitter in wireless communication.

Wireless receivers have a signal intensity range that is ideal for receiving signals. The RSSI readings that are higher or lower than this range may create problems with decoding the received signal, therefore readings that are within this range indicate improved signal quality.

Because of a newly introduced LE Power Control capability, devices that are monitoring the strength of a transmitted signal (the RSSI) from a connected device can request that the transmit power level used by its peer be changed either in the direction of the requestor or in the direction of its peer. Transmitters may also alter the transmit power on their own initiative, and the receiver will be informed of the change.

Using LEPC and maintaining the RSSI within the optimum range of the receiver offers a number of advantages, including the following:

  • Improved control over the signal’s quality is possible.
  • lowering the number of errors received at the receiving end
  • improving coexistence with other 2.4 GHz band signals, particularly those that are not Bluetooth-related (such as Wi-Fi and Zigbee).

Support for this feature is optional, but if both devices support it, they must utilize it for power management control if they are connected to the same network.

3. Enhanced Attribute Protocol (EATT)

EATT is an improved version of the original Attribute Protocol, which was first introduced in 1996 and is still in use today (ATT).

When compared to the original Attribute protocol, which operates in a sequential manner, the Enhanced Attribute Protocol provides a way to perform concurrent/parallel transactions between a Bluetooth Low Energy client and a Bluetooth Low Energy server, which may help to reduce the latency of operations in some applications.

When using a smartphone, for example, this is helpful since several applications may be interacting with a Bluetooth Low Energy device simultaneously. Through the use of EATT, an app’s Attribute transaction would not be stopped while another app’s ATT transaction was in process. This would effectively enable several applications to communicate with a Bluetooth Low Energy device simultaneously, possibly decreasing latency.

Specifically, the L2CAP layer’s Maximum Transmission Unit (MTU) is separated from the Attribute layer’s MTU in order to do this. Here’s an illustration to help you visualize what I’m talking about:

If the MTU of the L2CAP layer is smaller than the MTU of the Attribute layer, the L2CAP layer will break up the PDUs coming from the (upper) Attribute layer into smaller chunks and interleave the PDU chunks coming from different applications, causing the L2CAP layer to break up the PDUs coming from the (upper) Attribute layer into smaller chunks and interleave the PDU chunks coming from different applications.

For the sake of this example, we will have App A transmit a PDU that is bigger than the L2CAP MTU size, which implies that it will be split up into pieces of sizes up to the L2CAP MTU. This would enable the PDUs from App A and App B to be interleaved instead of App B’s PDU being stopped by App B’s PDU, as would otherwise occur.

The last couple of points we’d like to highlight are as follows:

  1. According to the specification, the Enhanced Attribute Protocol is an optional feature.
  2. It is necessary to encrypt the connection between the two Bluetooth Low Energy devices in order to do this. As a result, it is intrinsically more secure than the original Attribute Protocol, which was not improved.

What’s New in Core Spec Version 5.2

The Most Important Things You Should Know About Bluetooth 5.1 and 5.2

Despite the fact that the Bluetooth 5.0 standard was just recently introduced to the market, there have been two recent upgrades to the specification that include significant improvements that will have an effect on the future of wireless design: Bluetooth 5.1 and Bluetooth 5.2. It is the goal of this article to walk you through the most important elements of these upgrades so that your engineering team can predict what capabilities will be available for future design projects using Bluetooth.

Begin by reviewing the main features of Bluetooth 5.1, which are as follows: When the Bluetooth 5.1 standard was announced, the headlines were dominated by the addition of Angle of Arrival (AoA) and Angle of Departure (AoD) capabilities. However, there is more to this release than just AoA and AoD functionality.

1.New Direction-Seeking Skills

The improved direction-finding capabilities, AoA and AoD, introduced in Bluetooth 5.1, have sparked the greatest interest in the industry, and they are the ones that have created the most enthusiasm. Both the AoA and AoD techniques make use of numerous antennas that are placed in arrays in order to allow the ability to identify the relevant direction of a signal source. It is feasible to correctly anticipate the location of a signal in three-dimensional space using AoA or AoD in conjunction with other techniques such as Received Signal Strength Indicator (RSSI) triangulation or Ultra-Wideband (UWB) technology, which was previously not achievable.

It is essential to use arrays of several antennas in order to achieve the great accuracy promised for the Bluetooth 5.1 AoA and AoD capabilities. When dealing with a high number of co-located antennas, form factor may soon become a problem. However, integrated antenna technology enables engineers to make use of AoA and AoD without having to worry about the overall size of the antenna array.

Many experts believe that the new direction-finding capabilities constitute a significant step toward what many wireless engineers regard to be the Holy Grail of wireless devices: Real-Time Location Services, which is currently unavailable (RTLS). Much industry debate has taken place on this subject, and the excitement surrounding it is warranted since RTLS opens the door to applications that have been anticipated for the future of wireless.

It is true that Bluetooth 5.1 does not make real-time location services (RTLS) a reality today, but it enables engineers to make significant strides in that direction, particularly when AoA and AoD are combined with more powerful chipsets and other technologies that collectively provide more precise and more timely data about relative location, movement, and other factors, such as temperature.

Bluetooth SIG is expected to continue to make strides in this direction, but in the meantime, we have a set of features that will help us get closer to that goal by providing us with tools that can be applied to a variety of use cases such as asset tracking in warehouses, wayfinding for visitors in large facilities such as hospitals and museums, and limited contact tracing, among others.

2.Improvements to GATT cache

This feature of Bluetooth 5.1 is another that may or may not be relevant for every design project, but it is important for those in which connection speed is a key consideration. GATT (Generic Attribute) caching allows Bluetooth devices to cache the GATT table of generic attribute handles when they are connected to a GATT server. This allows Bluetooth devices to connect to GATT servers of the same kind more quickly in the future, while also conserving energy in the process.

When a device attempted to connect with another device, the previous versions of Bluetooth Low Energy conducted what is known as Service Discovery on each of the devices. It takes considerable processing power and time to conduct Service Discovery, and this amount grows exponentially as the number of connected devices grows. By caching the GATT database, that procedure is made faster for devices that are already known. Consider it the same as missing an introduction when you run into an old friend: you already know each other, therefore you don’t need to say anything more. In the same way, GATT caching achieves the same result—saving time and energy for devices for which speed and battery life are important considerations.

3.Randomized indexing of advertising channels

The final innovation mentioned in Bluetooth 5.1 is Random Advisory Channel Indexing, which enables devices to select advertisement channels randomly, rather than strictly as before needed. This enables fewer collisions and may make the connection more efficient. With the theme so far, fewer accidents and faster connections result in improved battery use and dependability.

The engineering community found the channel selection and data transmission technique to be too restrictive for many applications. In response to this feedback, the Bluetooth SIG has incorporated more flexibility in LE to enable engineering crews to randomly select devices between advertising channels, rather than to be rigidly predetermined and likely to collide with other advertisers at the same time, resulting in slow connection and high power consumption. It helps to randomize broadcasts from a gadget, which makes collisions with advertising nearby less probable. As a consequence, advertising messages will be received more successfully and connections will occur faster.

Each of the characteristics, separately and together, helps to speed up LE and make it more efficient and battery-intelligent by allowing engineers to adapt their designs and network deployments to suit their scenario of use.

Let us turn our attention to Bluetooth 5.2’s main features. Since the release was a point, it might be misunderstood that Bluetooth 5.2 did not contain significant enhancements, however, that is not the case. Bluetooth 5.2 includes several key improvements that may play a major role in future design initiatives.

4.Other Features

In the specification of Bluetooth 5.2, LE Audio will also have an audio effect beyond consumer devices, including Enhanced Attribute Protocol, LE Power Control, and LE Isochronous Channels. You will probably hear those three technologies mostly related to audio features described by the previous section, but engineers may also use them for additional design advantages and for new applications where reduced latency and multi-stream features are advantageous.

Engineers may utilize LE Isochronous Channels in applications where time-synchronized data transmission from one to many devices might have an effect. EATT may be utilized to enable several programs to concurrently access the LE stack while reducing interference that is caused by each data flow. One of the main advantages is reduced latency for each data stream, which is useful for many audio-excluding applications. LE Power Control plays an important part in the battery life of audio applications but may also have an equal effect on other applications by optimizing dynamically the transmission power utilized on the basis of signal quality if two devices interact. The intelligence included in this feature allows the device to discover methods to decrease energy consumption in real-time while maintaining signal strength quality and contributing to the coexistence of other adjacent wireless devices. These capabilities together provide the new Bluetooth 5.2 devices with great promise both in audio and beyond.


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