What’s new in Bluetooth 5.2

Bluetooth 5.2 was introduced in CES 2020 which focuses majorly on LE Audio and its enhancements.

Three Major improvements are

  • Enhanced Attribute Protocol
  • LE Power Control
  • LE Isochronous Channels

Enhanced Attribute Protocol:

An improved version of the Attribute protocol (ATT), called the Enhanced Attribute protocol (EATT), has been introduced along with some associated improvements to the Generic Attribute  Profile (GATT).

Key Improvements:

  • EATT supports concurrent transactions. This can reduce the end- to- end latency of one or more of the applications and improve the user’s experience of responsiveness.
  • In support of EATT a new L2CAP Enhanced Credit Based Flow Control Mode introduced which provides flow control and so allows applications to regard the protocol as reliable.
  • EATT has security advantages over unenhanced ATT as it may only be used over an  encrypted connection.

Enhanced Attribute Protocol: Capabilities and Benefits

EATT modifies the sequential transaction model, making concurrent ATT transactions possible when conducted over distinct enhanced ATT bearers. A new mode has been added to the L2CAP layer and is used by EATT. The new L2CAP mode provides flow control so that EATT can be regarded as reliable. MTU values at the ATT layer and L2CAP layer have been made independently configurable, and this may reduce latency experienced by some applications that share the stack with other applications.

Technical Highlights:

L2CAP Enhanced Credit Based Flow Control Mode – Receiving device gives no of credits to sending device like no of LE frames can be sent. (e.g) 1 credit = 1 LE Frame. So that receiving knows how many frames are expected.

Parallel ATT Transactions – The sequential transaction rule still exists when EATT is used, but its scope is now defined as being per instance of the Enhanced ATT Bearer. In other words, EATT transactions may be executing in parallel if they are supported by distinct L2CAP channels which use the Enhanced Credit Based Flow Control Mode, i.e. distinct Enhanced ATT Bearers

Discovering Support for EATT – The Generic Attribute Profile service has been updated to allow a client to determine supports EATT and, conversely, to allow the client to inform the server that it supports EATT. A new characteristic called Server Supported Features has been defined and must be included in the Generic Attribute Profile service if EATT is supported by the server. Bit 0 of the first octet of the value of this characteristic set to 1 means that EATT is supported. In Version 5.2 of the Bluetooth Core Specification has assigned meaning to two more bits. Bit 1 indicates whether or not the Enhanced ATT Bearer is supported by the client. Bit 2 indicates whether or not a new ATT PDU called Multiple Handle Value Notifications is supported. The client must write an appropriate value to this characteristic to inform the server of the features it supports.

Attribute Protocol PDUs

A number of new PDUs which may only be used over an enhanced ATT bearer have been defined.

1.The following new ATT PDUs, for use solely over an enhanced ATT bearer have been defined.

  • ATT_READ_MULTIPLE_ VARIABLE_REQ and ATT_READ_MULTIPLE_ VARIABLE_RSP
  • ATT_MULTIPLE_HANDLE_ VALUE_NTF

2.   The following ATT PDUs have had their specified behaviors refined to reflect the improved definition of an ATT bearer

  • ATT_PREPARE_ WRITE_REQ and ATT_PREPARE_WRITE_RSP
  • ATT_EXECUTE_ WRITE_REQ and ATT_EXECUTE_WRITE_RSP

3.   ATT PDUs which may not be used over an enhanced ATT bearer

  • ATT_EXCHANGE_MTU_ REQ and ATT_EXCHANGE_ MTU_RSP
  • ATT_SIGNED_WRITE_ COMMAND

LE Power Control(LEPC)

This feature provides Bluetooth LE devices optimize transmit power levels dynamically based on RSSI levels.

Link Layer PDUs introcuced for LEPC

  • LL_POWER_CONTROL_REQ – Sends delta value by which the sending device is requesting that the recipient device adjust its TxPower.
  • LL_POWER_CONTROL_RSP – Responds actual change in the transmit power and Acceptable power reduction value.
  • LL_POWER_CHANGE_IND – used to notify a remote device whenever the sender’s transmit power level has been changed autonomously in one or more PHY’s.

Host Controller Interface Commands and Events:

HCI defines several new commands and events that are related to LE Power Control. Both power management and path loss monitoring use cases are provided for

New HCI Commands

  • LE Enhanced Read Transmit Power Level
  • LE Read Remote Transmit Power Level
  • LE Set Path Loss Reporting Parameters
  • LE Set Path Loss Reporting Enable
  • LE Set Transmit Power Reporting Enable

New HCI Events

  • LE Transmit Power Reporting
  • LE Path Loss Threshold

LE Isochronous Channels

Primarily designed to support LE Audio, the next generation of Bluetooth audio, allows the communication of time-bound data to one or more devices for time-synchronized processing. it Can be used over connections or be broadcast to an unlimited number of devices in a connectionless fashion. An audio source can transmit audio for synchronized playback by small, private groups of devices (personal audio sharing) or to large collections of devices of unlimited sizes in public spaces, such as cinemas. Music sharing is only one application, however. LE Audio, built on top of the new LE Isochronous Channels, will offer a new standard for hearing aids and support assisted hearing systems in diverse locations, such as theaters, conferences, lecture halls, and airports.

 LE Isochronous Channels: Capabilities and Benefits

Time-Bound Data and Synchronized Processing:

The Bluetooth LE Isochronous Channels feature is a new way of using Bluetooth LE to transfer timebounded data between devices. It provides a mechanism that makes sure that multiple sink devices, receiving data from the same source, will render it at the same time. Data has a time-limited validity period, at the end of which it is said to expire. Expired data which has not yet been transmitted, will be discarded. This means that receiver devices only ever receive data which is valid with respect to rules regarding its age and acceptable latency.

New Audio Use Cases:

LE Isochronous communication provides the means by which audio, delivered from a source to multiple sinks, can be rendered at the same time, for properly synchronized playback. Audio, which for some reason is delayed after being generated at the source, expires and is discarded so that it does not affect the listening experience at the sink(s).

Summary

We discussed Bluetooth 5.2 features which focused on Bluetooth Low Energy related improvements.

We will discuss more about LE ISOC and LE audio more in separate blog.

Hope this is helpful. Only your feedbacks will help us improve


Image by StockSnap from Pixabay

What is Bluetooth Classic, Bluetooth Low Energy and Bluetooth Dual-Mode Device?

In this modern technological wireless world, from Speakers to Smart Devices Bluetooth has become a part of our daily life. Based on energy consumption and transmission speed all the Bluetooth devices around us are divided into the following types mentioned here.

  1. Bluetooth Classic Device
  2. Bluetooth Low Energy Device
  3. Bluetooth Dual-Mode Device

Bluetooth Classic Device

Most of the Bluetooth Devices are Classic devices. All the speakers fall under either Classic or Dual-Mode Type as High-Quality HD audio data cannot be transferred in Bluetooth Low Energy devices. Bluetooth Classic is ideal for devices like Speakers, Headsets & for calling purposes. Bluetooth Classic Devices has its Advantages and Disadvantages.

Advantages

  1. Classic devices support the transmission of a large amount of data through Bluetooth as Communication Medium.
  2. Classic devices send continuous data with a high transmission speed of up to 2.1 Mbps.
  3. As Classic devices are designed for transmitting continuous data, it is used by speakers for streaming High-Quality HD audio.
  4. Classic Devices are preferred for Calling purposes due to its efficiency in transmitting continuous data.

Disadvantages

  1. A classic device can cover only up to a range of 30 meters.
  2. A classic device can have an active connection only with a maximum of 7 devices thus it’s limited to have only 8 devices in a Piconet (Blueooth Network).
  3. On compared to Bluetooth Low Energy, Classic takes more time to pair & connect. It takes about 100 milliseconds.
  4. The Classic device continues to consume power even when the device is idle.
  5. Compared to a Low Energy device, a Classic device takes more time to send data. It takes about 100 milliseconds.

Bluetooth Low Energy device

Till Bluetooth Version 3.0, improvements to Bluetooth Technology were made only in terms of speed of data transfer through Bluetooth. In Bluetooth 2.0, Basic Rate (BR) was improved to Enhanced Data Rate (EDR). Further in Bluetooth 3.0, the improvement was made from Enhanced Data Rate (EDR) to High Speed (HS).

In Bluetooth 4.0, improvements to Bluetooth start to focus on Power Consumption. Power consumption is an important factor to be considered for Wireless Portable Devices. So in Bluetooth 4.0, Bluetooth Low Energy was introduced in the name of “Bluetooth Smart“. Bluetooth low energy devices are commonly called as LE or BLE devices.

Bluetooth Low Energy is ideal for devices like Smart Bands, Fitness trackers, Security Gadgets like Tiny Finder and Tags, IoT and Home Automation.

Advantages

  1. As the name suggests, Bluetooth Low Energy device consumes very less amount of power.
  2. Due to its nature of less power consumption, Low Energy devices can function up to 1-2 years with a 1000mAH Coin Cell Battery.
  3. Low Energy devices can cover long distances up to a range of 100 meters.
  4. Low Energy device takes less amount of time to get connected. It takes only 6 milliseconds.
  5. Low Energy devices take only 3 milliseconds to transfer data.
  6. Low Energy devices are suitable for IoT applications as it’s capable of forming a Piconet with a minimum of 100 devices.

Disadvantages

  1. Bluetooth Low Energy devices can transmit data only at a rate of 0.3 Mbps.
  2. Bluetooth Low Energy device cannot send continuous data and it can transmit only short bursts of data.

Bluetooth Dual-Mode Device

Dual-Mode devices are formed by implementing BLE functionality on a Classic device. Bluetooth Dual-Mode device was introduced in 4.0 for backward compatibility purposes as many Tablets and Smartphones released at that time won’t support Bluetooth 4.0. This was introduced to make use of the advantages of both Classic & Low-Energy devices.

Products of Beats like Powerbeats 3, Beats Pill+ & many of its other products are Dual-Mode devices. Dual-Mode was implemented in Speakers and Headsets for the following purpose.

  1. The dual-Mode device offers high flexibility as it simultaneously supports both Classic and Low Energy devices.
  2. Dual-Mode allows Speakers and Headsets to get connected to a Smartphone with less latency by making use of BLE functionality.
  3. Dual-Mode allows Speakers and Headsets to stream High-Quality HD audio by making use of Classic functionality.
  4. Dual-Mode increases range of Speakers and Headsets by making use of BLE functionality.

In short, Dual-Mode device acts as a Classic device with Smartphones which have Bluetooth Version below 4.0. In the case of Smartphones with Bluetooth Version 4.0 and above, it initiates connection as a BLE device and streams high-quality audio as a Classic Device. Dual-Mode enriches customer experience by faster Pairing, faster media controls and High-Quality audio.

Android application to get the type of Bluetooth Device

There is an Android application – Bluetooth Devices Info available in the Google Play Store to fetch the list of profiles supported by the Bluetooth device.

Screenshot of Android application displaying the type of Boat Stone 200 as Classic.

Instructions for using the Android Application – Bluetooth Devices Info.
  1. Download and install Bluetooth Devices Info from Google Play Store from this link
  2. Pair and connect the Bluetooth device to the smartphone.
  3. Open the Bluetooth Devices Info Android application.
  4. Select the Bluetooth device from the list of paired Bluetooth devices.
  5. Technical Information on the Bluetooth device is displayed.
  6. Make use of the share button to share the technical information.

Bluetooth Profiles

Bluetooth Profiles represents the list of compatible features provided by a Bluetooth Device. Each Bluetooth profile represents functionality. Adding a profile to the Bluetooth Device adds a functionality or feature to the Bluetooth device.

Image by 200 Degrees from Pixabay 

Commonly used Bluetooth Profiles are:

  • A2DP Advanced Audio Distribution Profile
  • AVRCP Audio Visual Remote Control Profile
  • HSP – Headset Profile
  • HFP – Hands-free Profile
  • HID – Human Interface Device
  • PAN – Personal Area Networking Profile
  • OPP – Object Push Profile

Advanced Audio Distribution Profile (A2DP)

Image by Pascal König from Pixabay 

Usage : Bluetooth Speakers, Headsets, Soundbars and other Bluetooth Audio Devices

Advanced Audio Distribution Profile (A2DP) commonly used in Bluetooth Speakers, Soundbars, Smartphones, Car Music Systems & Laptops. The functionality of this profile is to distribute audio data between two devices using Bluetooth as the communication Medium. Audio distribution is uni-directional and it also supports High-Quality stereo audio. Roles supported by A2DP devices are mentioned here.

  • A2DP – Source (SRC)
    A2DP-SRC is the Bluetooth Device which usually acts as Source for Bluetooth Audio. Bluetooth devices like Smartphones and Laptops usually acts as an A2DP Source device when music is played from a Smartphone or Laptop to a Bluetooth Speaker.
  • A2DP – Sink (SNK)
    A2DP-SNK is the Bluetooth Device which usually receives and streams audio transferred from Smartphone or Laptop through Bluetooth as the Communication Medium. Bluetooth Devices like Speakers, Soundbars, Car Music System & Home-Theatres act as A2DP-SNK devices.

Smart Devices like Google Home Mini and Amazon Echo products acts as both A2DP-SRC and A2DP-SNK device.

  • Smart Device as A2DP-SRC
    Google Home Mini and Amazon Echo Products act as the A2DP-SRC device when it is connected to a Bluetooth Speaker. In this case, Bluetooth Audio streams from Smart Device to Speaker.
  • Smart Device as A2DP-SNK
    Google Home Mini and Amazon Echo Products act as the A2DP-SNK device when it is connected to a Smartphone or Laptop. In this case, Bluetooth Audio streams from Smartphone or Laptop to Smart Device.

Audio Visual Remote Control Profile (AVRCP)

Image by StockSnap from Pixabay 

Usage : Bluetooth Speakers or Headsets with Media Control Buttons

Audio Visual Remote Control Profile (AVRCP) is commonly used along with Advanced Audio Distribution Profile(A2DP). This profile allows Speakers and Headsets to control the playback of Audio and Video through Bluetooth as the communication Medium with the help of Media control buttons like Play/Pause, Previous & Next. Some headsets and Speakers like Beats Pill +, Bose Soundlink Color and Powerbeats 3 do not have explicit media control buttons like Play/Pause, Previous & Next but it supports AVRCP operations with the help of Multi-Functional Button and Volume Buttons.

Multi-Functional Buttons in Headsets and Speakers performs media operations by

  • Single-Tap : Play/Pause
  • Double-Tap : Next
  • Triple-Tap : Previous

Sometimes Volume Buttons in Headsets and Speakers perform Media operations like Previous & Next.

  • Press & Hold Volume + : Next
  • Press & Hold Volume – : Previous

Note: Mentioned above are commonly used media controls, please refer to your speaker or Headset’s User Guide for hidden AVRCP Controls.

Roles supported by AVRCP devices are mentioned here.

  • AVRCP-Controller (CT)
    AVRCP-Controller is the Bluetooth Device that controls media playback through Media Control buttons. Bluetooth Devices like Speakers, Soundbars, Car Music System & Home-Theatres act as AVRCP-CT devices as it controls the media operations with the help of its Media Control Buttons.
  • AVRCP-Target (TG)
    AVRCP-Target is the Bluetooth Device that responds to AVRCP Media Playback controls from the AVRCP-Controller device. Bluetooth Devices like Smartphones and Laptops act as AVRCP-TG devices as it responds to Media Playback controls from AVRCP-CT device like Speaker.

Smart Devices like Google Home Mini and Amazon Echo products acts as both AVRCP-CT and AVRCP-TG device.

  • Smart Device as AVRCP-CT
    Google Home Mini and Amazon Echo Products act as the AVRCP-CT device when it is connected to a Smartphone or Laptop. In this case, media playback of Song or Video streaming in Smartphones is controlled by Voice user Interface (VUI) operations from Smart Device like “Hey Google, Play Next” or “Alexa, Play Next”.
  • Smart Device as AVRCP-TG
    Google Home Mini and Amazon Echo Products act as the AVRCP-TG device when it is connected to a Bluetooth Speaker. In this case, media playback of Cloud music steaming in Smart Device is controlled by Media control buttons of Bluetooth Speaker.

Headset Profile (HSP)

Image by Esa Riutta from Pixabay 

Usage : Bluetooth Headsets and Speakers which supports basic calling feature

Headset Profile (HSP) adds basic calling functionality to Bluetooth Speaker or Headset. This profile allows the user to engage in Cellular or Online calls through Bluetooth Speaker or Headset. HSP is a basic profile as it allows the user to perform basic operations like attending and disconnecting the call.

Hands-Free Profile (HFP)

Image by Jess Watters from Pixabay 

Usage : Car Music Systems, Headsets with Alexa, Siri or Google Assistant support & Headsets which supports Redial feature.

Hands-Free Profile was introduced as an improvement to Headset Profile. Hands-Free Profile supports advanced calling features compared to basic functionalities of the Headset Profile. This profile allows users to initiate and engage in calls without interacting with their smartphones. This profile is usually implemented in Car kits, Headsets with Redial feature, Headsets which support interaction with Artificial Intelligence like Alexa, Siri & Google Assistant.

  • HFP in Car-kits
    Car-Kits allows the user to initiate and engage in a call by syncing the contacts between Car-Kit and Smartphone. The User can initiate the call to a Phone-book contact without interacting with his Smartphone by selecting & dialling a contact through Car-Kit’s display.
    Example : Android Auto and Apple CarPlay
  • HFP in Headsets which supports redial
    Some headsets allow the user to initiate the call with last dialled contact by double-tapping the call button of the headset.
  • HFP in Headsets which supports Alexa, Siri and Google Assistant
    Some headsets allow the user to initiate a call with the help of Artificial intelligence like Alexa, Siri or Google Voice Assistant. A user can initiate a call with Voice User Interface (VUI) command “Hey Siri! Call Mom”
    Example : Apple Airpods, Jabra Elite 65t and Sony WH1000XM3.

Human Interface Device Profile (HID)

Image by StartupStockPhotos from Pixabay

Usage : Keyboard, Mouse and Game Controller

Human Interface Device (HID) Profile allows the user to interact with Laptops, Desktops, Tablets, Smartphones, Smart TVs & Console Games using Bluetooth as the Communication Medium with the help of Bluetooth Keyboard, Mouse, Remote & Game Controllers.

Manufacturers like Apple, Sony & Microsoft started to use HID profile by implementing in its Keyboard, Mouse & Game controllers to interact with their products like MAC, PlayStation & Xbox. Amazon manufactures its Fire TV remotes and Echo Remotes by implementing HID Profile in its Bluetooth Remotes.

Popular Bluetooth Devices which use HID profiles are Apple Magic Keyboard, Apple Magic Mouse, Xbox Wireless Game controller, PS4’s Dualshock 4 Wireless Controller, Amazon Fire TV Remote & Echo Remote.

Personal Area Networking Profile (PAN)

Personal Area Networking (PAN) Profile allows the user to share the network connection between the Smartphone and Laptop through Bluetooth as the communication medium. A user can share his network through the “Bluetooth Tethering” Option in the Smartphone.

Object Push Profile (OPP)

Object Push Profile is the commonly used profile from Classic Mobile Phones with basic features to the latest Smartphones. This profile allows the user to transfer files between the Smartphones or Classic Mobile Phones with basic features.

Android application to get the list of Supported Profiles

There is an Android application – Bluetooth Devices Info available in the Google Play Store to fetch the list of profiles supported by the Bluetooth device.

Screenshot of Android application displaying the list of profiles supported by Boat Stone 200.

Instructions for using the Android Application – Bluetooth Devices Info.
  1. Download and install Bluetooth Devices Info from Google Play Store from this link
  2. Pair and connect the Bluetooth device to the smartphone.
  3. Open the Bluetooth Devices Info Android application.
  4. Select the Bluetooth device from the list of paired Bluetooth devices.
  5. Technical Information on the Bluetooth device is displayed.
  6. Make use of the share button to share the technical information.


How to get Technical Information of a Bluetooth Device

Bluetooth devices have become an integral part of our day to day life. We are using Bluetooth devices like Speaker, Headset, Home Theatre, Keyboard, Mouse in our day to day activities. We started to love Bluetooth devices as it avoids messy physical wires.

Each Bluetooth device has technical information like MAC Address, Profiles supported, UUID. Bluetooth Device’s technical information can be grabbed using an Android Application – Bluetooth Devices Info in Google Play Store.

The Android Application provides essential technical information of a Bluetooth Device like

  • Bluetooth Device Name
  • MAC Address
  • Bluetooth Device Type
  • List of Bluetooth Profiles supported by the Bluetooth Device.
  • List of UUIDs.

Screenshot of the Android application displaying technical details of Boat Stone 200.undefined

  • Bluetooth Device Name
    Name assigned to the Bluetooth device by Manufacturer.
  • MAC Address
    MAC Address is a unique 48-bit address assigned to Bluetooth Device. It is usually represented as a 6-byte hexadecimal address separated by a colon. The first three bytes of MAC address is Organizationally Unique Identifier(OUI) which represents the manufacturer of the Bluetooth Device and the second three bytes of MAC address is assigned by the manufacturer to the Bluetooth Device.

    MAC Address of Boat Stone 200 mentioned above in the screenshot is “FC:58:FA:C8:1D:FC“. The first three bytes “FC:58:FA” represents the organization “Shen Zhen Shi Xin Zhong Xin Technology Co., Ltd.”
  • Bluetooth Device Type
    Bluetooth devices are of three types: Classic, Low Energy (LE) & Dual-Mode. For further information on Bluetooth Device type, read this blog on Bluetooth Device Types.
  • List of Bluetooth Profiles
    Bluetooth Profiles represents the list of compatible features provided by the Bluetooth Device. For further information on Bluetooth Profiles, read this blog on Bluetooth Profiles.
  • UUID
    UUID is a 16-Bit Universally Unique Identifier. This represents the list of services provided and the organization of the Bluetooth Device.
Instructions for using the Android Application – Bluetooth Devices Info.
  1. Download and install Bluetooth Devices Info from Google Play Store from this link
  2. Pair and connect the Bluetooth device to the smartphone.
  3. Open the Bluetooth Devices Info Android application.
  4. Select the Bluetooth device from the list of paired Bluetooth devices.
  5. Technical Information on the Bluetooth device is displayed.
  6. Make use of the share button to share the technical information.