Bluetooth 5.2 vs 5.3 – Specifications & Feature Comparison

In June 2016, the Bluetooth Special Interest Group declared Bluetooth v5. As per their press release, Bluetooth v5 will be known as Bluetooth 5. It comes with increased speed, range, and broadcast messaging capacity. It aims to deliver robust, reliable Internet of Things (IoT) connections that make smart buildings, intelligent homes, and outdoor use cases a reality.

Also Read – Bluetooth 5.1 vs 5.2

Compared to Bluetooth 5.1, there have been significant improvements brought in Bluetooth 5.2 and 5.3 for the ultimate benefit of users. Though the Bluetooth 5.3 specification might not appear a massive leap, such enhancements are significant additions to enhance user experience, device performance, and power consumption. Let’s first get into details of Bluetooth 5.2 and 5.3:

Bluetooth 5.2:

The Bluetooth SIG published the Bluetooth Core Specification Version 5.2 on 31^st December 2019.

This new specification adds the following new features:

1. Enhanced Attribute Protocol (EATT), an enhanced version of the Attribute Protocol (ATT)
2. LE Power Control
3. LE Isochronous Channels
4. LE Audio is designed on top of the latest 5.2 features.

The Bluetooth SIG announced BT LE Audio in January 2020. Compared to standard Bluetooth Audio, the Bluetooth Low Energy Audio leads to lower battery consumption and sets up a standardized system of audio transmission over BT LE. Moreover, Bluetooth LE Audio also enables one-to-many and many-to-one broadcasts. So, it allows multiple receivers from a single source or a single receiver for various sources. The latest LC3 codec is used. BLE Audio would also add support for hearing aids.

Now let’s go through the description of prominent aspects of Bluetooth 5.2:

1. Enhanced Attribute Protocol (EATT):

Bluetooth version 5.2 is equipped with an advanced version of the original Attribute Protocol (ATT) known as Enhanced Attribute Protocol (EATT). Basically, ATT works in a sequential manner which implies that transactions are carried out one at a time. However, EATT can accomplish concurrent or parallel transactions between a Bluetooth LE client and a server.

EATT streamlines breaking down L2CAP packets from various applications and merging them into smaller chunks that are more manageable. Consequently, transactions from two or more applications could be finished simultaneously.

The EATT feature improves user experience when multiple applications are operating on the same Bluetooth LE stack. Also, it decreases overall latency. It is important to note that EATT is optional per the specification. It needs an encrypted connection between both Bluetooth LE devices, making it more secure than ATT.

2. LE Power Control Feature (LEPC):

LE Power control allows managing power transmission between two connected devices that support Bluetooth version 5.2. Generally, wireless receivers come with an optimal received signal strength range which offers superior signal quality. Those receivers with a signal strength lower or higher than this optimal range can have problems when decoding signals.

Through LEPC, a receiving device can supervise its partner device’s received signal strength indicator (RSSI) signal and ask for altering the transmit power level in either direction. Instead, a transmitter can adjust the transfer power and transmit that information to the receiver.

Consequently, it promises that both devices stay in their optimal signal ranges. Also, it decreases error on the receiving end and reduces power consumption via dynamic power management.

The power management through LEPC also enhances coexistence with other signals within the 2.4 GHz band, including signals from Zigbee and WiFi.

3. Isochronous Channels (ISOC):

One of the significant feature upgrades is the support for isochronous channels. These channels can be used on any of the physical layer variants of LE. They can be used on 1M, 2M, and LE Coded configurations S=2 and S=8.

The latest isochronous channels of Bluetooth 5.2 support data retransmission for BIGs and CIGs, but in varied ways. For CIGs, the master transmits a packet to the slave, and then the slave reverts with a packet for every sub-event. For BIGs, only the master sends a packet in every sub-event. ISO intervals can vary from 5 milliseconds to 4 seconds.

Isochronous channels support connection-oriented and connectionless communication:

i. Connection-oriented communication:

When this mode is enabled, each data stream is known as a Connected Isochronous Stream (CIS). When CISes have to be synchronized, they are linked in a Connected Isochronous Group (CIG). Those CISes part of the identical CIG share reference data to synchronously stream on multiple receivers.

Devices supporting Bluetooth 5.2 can also set up multiple CIGs. Furthermore, CIGs facilitate bidirectional data transfer, making it more straightforward for devices to transmit control data to the source device.

ii. Connectionless communication:

When this mode is enabled, a single source, for example, a smart TV, can stream its data to multiple synchronized streams. Each stream is known as a Broadcast Isochronous Stream (BIS), whereas each group of BISes is known as a Broadcast Isochronous Group (BIG). Similar to CIGs, devices with Bluetooth 5.2 can set up multiple BIGs.

4. LE Audio:

LE Audio provides a significant improvement on Bluetooth LE and Bluetooth Classic. It utilizes reduced power and reduced bandwidth to provide superior quality audio transmissions. So, it improves quality and prolongs the device’s battery life.

LC3 optimizes the existing codec of Bluetooth LE by compressing audio transmissions and scaling them down to very extremely bit-rates without negatively affecting the audio quality.

LC3 and Bluetooth version 5.2 will reform the way consumers use Bluetooth audio accessories. Because LC3 is implemented with multi-stream capabilities and support for multiple synchronous connections (by default), True Wireless users can benefit from improved battery life and faster pairing. The improved battery life offers better efficiency and a more extended range. So, this Bluetooth standard is helpful for a pair of wireless headphones and a voice-controlled smart speaker.

The support for Piconet Link Manager Mode is added. This enables devices to connect without taking turns to prevent interference.

Bluetooth 5.3:

On 13^th July 2021, the Bluetooth SIG published the Bluetooth Core Specification Version 5.3. This Bluetooth version features lower latency, lower interference, enhanced battery life, and enhanced security.

It comes with the following feature enhancements:

• Connection Subrating
• Channel Classification Enhancement
• Periodic Advertisement Interval
• Encryption Key Size Control Enhancements

Note: Alternate MAC and PHY (AMP) Extension are removed in Bluetooth 5.3.

Now let’s go through the description of prominent aspects of Bluetooth 5.3:

1. Connection Subrating:

Specific devices spend much of their time in a low-duty cycle connection to conserve power. However, when higher bandwidth is required to support a particular application use case, then the connection parameters should be altered as fast as possible.

Connection Subrating speeds up the connection parameter updates with minimal delay. It conveys a better user experience and simultaneously retains the power-saving characteristics of low-duty cycle connections. Specifically, this can be useful in innovative medical devices like a smart blood glucose meter.

2. Channel Classification Enhancement:

Bluetooth LE Peripheral devices can now offer a connected Central device having radio channel classification data. This data might be used by the Central device while carrying out channel selection in adaptive frequency hopping.

Channel Classification Enhancement enhances reliability and throughput by decreasing the odds of interference occurring at the Peripheral while the Peripheral and Central devices are not physically near each other. Using this feature, an example of the device can be a vibration sensor connected to the smartphone and an industrial rotating machine. The vibration sensor works as a peripheral device, whereas the smartphone functions as a central device. The condition monitoring staff experience interferences of varying magnitudes and from varied sources.

3. Periodic Advertising Enhancement:

The standard extended advertising payload format’s AdvDataInfo (ADI) field can now be implemented in the AUX_SYNC_IND protocol data units (PDUs). These units are broadcasted when a device performs periodic advertising.

Now the Bluetooth Low Energy (LE) controllers might use the information in the ADI field to identify those packets that include retransmitted copies of identical or semantically correspondent data. Moreover, it removes such packets to avoid redundant processing on the nodes. So, the overall throughput is unaffected by retransmitted packets.

4. Encryption Key Size Control Enhancement:

Encryption key sizes are settled upon by the connected devices’ controllers in Bluetooth BR/EDR. This change enables a host to notify its Bluetooth BR/EDR controller about the minimum acceptable key size through the Host Controller Interface (HCI).

This enhancement lets the Bluetooth BR/EDR controllers more efficiently notify the host of the outcome of key length negotiations. This new feature of Bluetooth 5.3 will be more beneficial to IoT applications like access control, portable medical devices, door locks, and commercial lighting.

Removal of the Alternate MAC and PHY (AMP) Extension:

The Alternate Media Access Control and Physical layer extension (AMP) enables a Bluetooth system to incorporate single or multiple secondary controllers and a primary Bluetooth BR/EDR controller. But in high-quality Bluetooth products, this extension is rarely found. Hence, the Bluetooth SIG has discarded this feature from the Bluetooth 5.3 specification. But this new version can qualify products that utilize AMP against a previous Bluetooth Core Specification version.

Comparison of Bluetooth 5.2 vs Bluetooth 5.3:

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If you want to speed up connection parameters for high-duty cycle applications while ensuring power conservation, then Bluetooth 5.3 is a better option.

It offers increased reliability and throughput by reducing interference occurring at the peripheral. Redundant processing is avoided. For IoT applications, Bluetooth 5.3 is a better alternative.

If you want to have efficient transactions between two or more applications simultaneously with reduced latency, then Bluetooth 5.2 is a better pick. It is a better option for optimal signal transmission with reduced power consumption.

For flawless streaming on multiple synchronized streams, Bluetooth 5.2 is a better pick. LE Audio decreases consumption of power and bandwidth, which makes Bluetooth 5.2 a better option for high-quality audio transmission.