Bluetooth Core Specification 5.2 Version Feature Overview

The latest version of Bluetooth 5.2: Specification Feature Overview...

by Bestwireless
Bluetooth 5.2

Bluetooth technology is a wireless connection that allows devices that are Bluetooth enabled to communicate and share information. Bluetooth operates within a short distance of about 10 meters. With Bluetooth technology, you will be able to create personal area networks.

There are different versions of Bluetooth and each version has been improved to have fast and stable connections. The latest Bluetooth technology as of now is Bluetooth version 5.2 which has more advanced features than the previous versions. This version allows more than one device to connect and share information. Bluetooth 5.2 technology was released on January 6, 2020.

Overview Of New Bluetooth 5.2 Features:

The new Bluetooth version Brings a few new features. Below I describe every breakdown of the new feature of the 5.2 version. Let Check the update…

01. Enhanced Attribute Protocol

This an improved protocol of the earlier version of Attribute-protocol (ATT). EATT (Enhanced Attribute Protocol) supports simultaneous transactions and permits the interleaving of L2CAP-packets and ATT Maximum-Transmission-Unit which is changed when the connection is ongoing. This will give an enhanced user experience where more applications use the Bluetooth Low-Energy (LE) stack concurrently.

In conjunction with the EATT, there exist a new L2CAP-mode (Enhanced Credit-Based Flow Control Mode.). L2CAP mode allows a flow of control and also enables applications to regard the protocol as dependable.

EATT is advantageous over unenhanced ATT in terms of security because it can only be utilized over an encrypted link.

02. LE Power Control

The improved LE power control allows the devices to dynamically improve the transmission energy utilized when two devices are communicating. The Bluetooth LE receivers monitor signal strength & ask for transmission power-level modifications in devices that are connected.

Bluetooth controller monitors & reports path-loss changes to a Bluetooth host with the help of zones concept.

Advantages of LE Power Control:

  • Consumes less power with the help of dynamic power management on connected devices.
  • It improves reliability via active sustenance of receiver signal strength
  • Improves the relation with other wireless devices that are utilizing the 2.4-GHz frequency range.

03. LE Isochronous Channels

This feature is majorly made to support LE-Audio. This feature allows the communication of time-bound information to one or more applications for time-synchronized processing. LE Isochronous Channels make it possible for one to have new topologies and use cases.

LE Audio, which is built at the top of this new LE Isochronous-Channels, will provide a new standard for listening aids & support assisted hearing systems in various locations which include conferences, theaters, airports, and lecture halls.

Enhanced Attribute Protocol Explanation

The Bluetooth-Low-Energy Stack with ATT, GAP, and GATT

Bluetooth 5.2

Bluetooth Low Energy stacks comprise 2 architectural components which include the controller & host. Each of these components contains various stack layers. Host Controller Interface outlines a sequence of commands that are used by the host to communicate with the controller.

Bluetooth mesh devices have various host components that consist of layers of the mesh protocol stack.

  • Attribute Protocol

Bluetooth devices contain a collection of special data entities which include services, descriptors, and characteristics. All these attributes are organized into something known as an attribute table. The attribute Protocol is utilized by an ATT client to find out details of an attribute table remotely, a connected device known as the ATT server.

ATT is among the major mechanisms in which applications that are connected in Bluetooth devices will interact with each other with the help of PDUs the protocol-defines & procedures defined at higher level specifications (Generic Attribute Profile).

  • Logical Link Control & Adaptation Protocol (L2CAP)

Bluetooth 5.2

L2CAP is reliable for flow control, segmentation & reassembly of service data units (SDUs), and protocol multiplexing. L2CAP utilizes the idea of the channel to isolated sequences of packets that pass between the layers of the stack. Fixed channels need no set-up. Channels are also created & associated using a protocol via a specific Protocol Service-Multiplexer (PSM) value.

  • Concurrency & Latency

Several concerns are related to ATT & L2CAP that have consequences for latency when more applications are utilizing the stack.

i).  ATT Sequential-Transaction Model

Bluetooth 5.2

ATT makes use of a sequential operation model. With Bluetooth version 5.1, it meant that only one ATT transaction can be carried out at a time until the in-progress transaction is completed.

ii). ATT MTU & L2CAP MTU Sizes

In Bluetooth version 5.1, the MTU given to the L2CAP-layer has a 1-1 communication with the MTU-value which is assigned to the ATT-layer. This will lead to L2CAP not being able to interleave the processing of L2CAP-SDUs from various applications & different ATT-PDUs. This would be beneficial in other circumstances.

  • MTU Renegotiation

ATT MTU is negotiated straightaway after connecting with the use of the ATT-Exchange-MTU request & response PDUs. Once negotiated, it cannot be altered throughout this connection. When another application on a similar device is started on a similar connection, and the MTU size isn’t big enough for this purpose, then it has no choice but to fail, offering the user a poor experience.

  • Enhanced ATT Capabilities & Benefits

EATT improves the successive transaction model which makes simultaneous ATT transactions happen when it is conducted via different improved ATT-bearers. The improved model has an L2CAP layer which is utilized by EATT. L2CAP mode gives a flow-control so that EATT could be viewed as reliable.

  • Enhanced ATT Technical Highlights

Bluetooth 5.2

EATT always utilizes dynamic instead of fixed-L2CAP channels though with a present protocol service-multiplexer (PSM) value. Up to five channels can be asked at a period of using the present L2CAP_CREDIT_BASED_CONNECTION_REQ PDU. GATT-layer will take care of a pool of bearers & assign them to the servicing of requirements, as required.

The enhanced ATT protocol permits concurrent processes to be held by the stack. The Generic-Attribute Profile service is improved to enable a client to decide whether or not a linked server is compatible with EATT & conversely. This will allow the client to notify the server that it is compatible with EATT.


LE Power Control Explanations

  • Power regulation in Bluetooth BR/EDR

Bluetooth BR/EDR has a power control ability unlike in Bluetooth version 5.1.

  • Transmission Power & Electrical Power use

When two devices are communicating via Bluetooth one of the devices acts as a transmitter while the other device act as a receiver. The transmitter device will give out its signal with a certain power level which is also known as TxPower and it is measured in dBm. The power consumption by Bluetooth devices increases with an increase in TxPower levels.

  • Path Loss

Bluetooth 5.2

The level of the transmitted signal at the receiver point will be low than the level while on the transmitter. This is brought about by a phenomenon identified as path loss. This is created by some factors among them being the fact that the radio-wave-front increases to cover a bigger area which will lead to spreading the signal’s energy as it comes outwards from the transmitter device. This will result in a decrease in energy at every point.

Physical obstacles can also decrease signal strength via absorption. The signal will reflect & refract and as a result signal strength is reduced.

  • Background Errors, Range and Noise

Electromagnetic radiation is all over the environment and it is referred to as background noise. According to the Bluetooth 5.2 Core-Specification when a basic error rate surpasses 0.1 percent, then the communication is viewed as no longer operating well to be sustained. At this point, the connection will be lost and the transmitter and the receiver will be out of range.

  • Optimal Received Signal-Strength

Receivers have an ideal received signal-strength range which will give optimal performance. This is also known as the golden-range or the golden receive power-­range. When the receivers get high signal levels, it may get saturated & as a result causing the link between the connected devices to fail. Furthermore, when the received signal strength is very low, the error rate will decrease and this can affect the throughput which has packets that can’t be decoded with no error requiring to be resent. When the error rate surpasses the allowed limit, the connection link will fail.

  • Low-Power Communication & Power Control

The major aim of low-power Bluetooth communication is to sustain the needed communication which utilizes the cases to the best level of dependability whilst utilizing as low electrical power as possible. It’s a great success of the Bluetooth 5.2 version.

  • Coexistence

Bluetooth functions in a frequency range of 2.4 GHz.  It isn’t the only technology that utilizes this range. This brings the problem which is related to sharing a given section of the radio spectrum by various radio technologies and it is identified as coexistence.

  • Hysteresis

This an occurrence that is shown by some devices. It involves lag between the changes on one property & another that has a causal link with it.

  • Capabilities & Benefits of LE power control

i). Power management

LE Power-Control feature gives Bluetooth LE devices the skill to exercise power-management through enhancing transmit-power levels energetically.

ii) Path Loss Monitoring

Path loss is in Bluetooth Core Specification, which is defined as the variation between the remote-transmit power & the normal local RSSI measurement for the link. The LE Power-Control feature enables the host to describe 2 or three path loss zones as High, Middle, and Low.

  • Discovering Support for LE-Power Control

Devices can only utilize a particular LE-power control process if all devices are capable of supporting the relevant sections of this feature. The Link-Layer outlines the feature exchange process & this will enable peer devices to interchange a bit-mask knows the Feature-Set.

LE Isochronous Channels explanation

  • Physical Layer Variants

Bluetooth LE outlines more physical layer-variants which are known as Phys. Supported PHYs give various symbol rate & range capabilities.

  • Slots & Channels

Advanced digital-radio communications tech uses one or more structures that enable the radio medium to be used by more transmitting devices. The schemes are normally referred to as more access methods. If there is more transmission happening on a specific frequency within the same time, the packets are said to collide & the data gets corrupted hence should be retransmitted.

Bluetooth utilizes a combination of 2 multiple-access methods that are used to share the radio medium. They are known as Frequency Division-Multiple Access (FDMA) & Time Division-Multiple Access (TDMA).

  • Bluetooth Data Transport Architecture

Bluetooth 5.2

The architecture of Bluetooth explains a number of concepts that collectively comprise Bluetooth data transport architecture. The major concepts include Physical Link, Physical Channel, Logical Transport & Logical Link.

  1. Physical Channel outlines one or more different methods of communication via Bluetooth.
  2. A physical Link is a specific physical channel that specifies certain features of a link, which includes the use of power control.
  3. Logical links & transports have different parameters that are made to give the best means of assisting a precise set of data communication necessities over a physical link via the use of a particular physical channel type.
  • Extended Advertising

Advertising is a Bluetooth-LE process that gives a connectionless communication way. Bluetooth 5.2 Advertising utilizes 2 sets of channels which are referred to as the primary & secondary channels. The primary channel consists of the other three primary channels & the secondary channel has another 37 secondary channels.

  • Bluetooth 5.2 Audio

Bluetooth connection is used in more areas with different devices. However, audio remains to be the biggest application in Bluetooth technology. Improved Audio Distribution-Profile (A2DP) describes how Bluetooth could be utilized for best quality sound applications which includes music streaming.

Capabilities and Benefits of LE Isochronous Channels

i). Time-Bound Data & Synchronized Processing

Bluetooth LE-Isochronous channels highlights is a new way of utilizing Bluetooth LE to transmit time-bounded information between devices. Expired information that hasn’t yet been conveyed, will be ignored.

ii). New Audio Use-Cases

LE-Isochronous communication was majorly made for utilizing audio devices & systems. New topologies, new use cases, new product kinds will be likely with the new Bluetooth-LE isochronous channels characteristic. The use of Bluetooth-LE for sound is called LE Audio.

  • Technical Highlights of LE Power Control

Bluetooth information transport architecture has been improved to support isochronous channels, which might be connectionless or connection-oriented. Connection-oriented isochronous channels utilize the LE-Connected Isochronous-Stream logical transport & support bi-directional communication. LE-CIS stream will provide point-to-point isochronous communication between 2 joined devices.

Connectionless-isochronous communication utilizes Broadcast Isochronous Streams & just supports one-directional communication. CIS-streams are part of groups known as Connected Isochronous-Groups, each of these may have more CIS instances. Reliability is to be improved using retransmissions of the same packets within a series of sub-events on either CIS streams or BIS.


Bluetooth 5.2 version has more advanced features and the latest devices will have this technology fitted in. This Bluetooth version uses low energy. There will be also reduced latency. This version is more reliable.

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