Ⅰ.  About Bluetooth LE  Audio Technology

Bluetooth audio has become a mainstream solution on the market, and most earbuds and headphones use the existing classic Bluetooth technology. However, LE Audio will be a game changer with the next generation of Bluetooth audio technology. Compared to classic Bluetooth, LE audio is transmitted over the Bluetooth Low Energy radio and provides high audio quality and lower power consumption. LE Audio has more attractive new features such as multi-streaming, broadcast audio streaming, and enhancements for Bluetooth audio use cases.

Ⅱ. Features of Bluetooth LE Audio

LC3 codec audio:

An audio codec is typically used to compress an audio stream on the sender side and decompress it on the receiver side in order to play it. LE Audio proposes the "Low Complexity Communication Codec" (LC3), a revolutionary codec that enables good quality while consuming less power.   LC3   offers higher quality at lower data rates, as well as the ability to balance audio quality and battery consumption. The data rate is around 50% lower than the   SBC   codec for the same quality audio.

The default  SBC codec in current Bluetooth audio is highly adaptable for sample rates up to 48kHz and 16-bit depth and can send data at up to 345kbps. However, its compression algorithm results in significant data loss. The LC3 audio codec will support a variety of sample rates ranging from 8 to 48 kHz, as well as bit depths of 16, 24, and 32 bits per audio sample. LE Audio requires the  LC3 codec, which supports multiple audio channels and provides customers with higher-quality audio, more powerful audio, longer battery life, and a smaller device form factor.

Figure. 1 Bluetooth Codec Comparison

Low Power Audio (LE Audio): The moniker LE Audio (Low Energy) says it all. Bluetooth Low Energy RF is supported by its audio capabilities. Clearly, it offers up a slew of new possibilities for low-power audio applications. The majority of use cases will be battery-powered wearables in this scenario.

The  LC3 codec helps achieve the same music quality at a 50% lower bit rate, which means the LE radio doesn't need to stay active as long, saving battery. The same audio quality can be achieved in a smaller form factor and with a smaller battery.

Multi-Stream Audio: Multi-Stream Audio allows a source device to send several audio streams to one or more audio sink devices in a coordinated manner. For example, the source device could be a smartphone, and the sink device could be one or more earbuds. LE Audio uses the Sync Channel functionality to allow a range of applications, including real TWS. This feature allows several audio streams to be shared between the source and sink devices, with a synchronization error of roughly 10-15 microseconds. This feature allows for smoother switching between multiple audio source devices and makes the   A2DP   and HFP profiles of conventional Bluetooth more functional.

Figure. 2 Multi-Stream Audio

Linked Isochronous Streams (CIS) enable logical transit between connected devices to transfer data on either side of an ACL, allowing LE Audio  Multi-Streaming (Asynchronous Connected Link). At each CIS event, each CIS can employ fixed or variable data size, framed or unframed data, single or many packets, and framed or unframed data. Data flow in CIS can be unidirectional or bidirectional between devices, and protocols are used to increase packet delivery dependability.

Figure. 3 Classic Bluetooth and LE Audio

Broadcast Audio: a cutting-edge function that expands the range of applications for Bluetooth audio. It enables a single audio source device to send audio streams to a large number of audio sink devices.

The "Broadcast Isochronous Stream" can be used to allow broadcast audio (BIS). It's used to send out one or more data streams at the same time to all receiving devices within range. On each BIS event, it supports constant or variable size, framed or unframed data, and numerous packets. It uses a one-way data flow from the source to the sink device that does not require acknowledgment. To improve delivery reliability,  BIS packets can be retransmitted by increasing the number of sub-events in each  BIS event.

Figure. 4 Broadcast Audio

Receiving devices within the broadcast audio range employ one of two broadcast mechanisms to join the audio stream:

Open broadcast: Any receiving device within range of the broadcast audio can begin receiving it.

Closed broadcast: To participate in the audio stream of any source device, any receiving device within range must enter a key.

The following categories can be used to categorize audio sharing:

Personal Audio Sharing: Users can share their personal mobile music with their friends and family.

Audio sharing based on location: Audio source devices can broadcast audio streams to audio sink devices in their immediate vicinity.

An airport authority, for example, can set up an audio source device with a standard announcement broadcast audio stream, and audio sink devices (passenger earphones) within range can receive the same audio stream at the same time.

Figure. 5 Personal and Location-Based Audio Sharing

Ⅲ. Bluetooth LE Audio Applications

LE Audio will revolutionize the Bluetooth audio market with a variety of characteristics that will enhance a variety of Bluetooth audio applications. Let's look at some examples of industry-specific applications:

Medical industry:

Hearing aids: Bluetooth audio is bringing an increasing number of people to their audio goods. The demand for single or dual hearing aids with telephony, low power consumption, and low latency is steadily increasing.  LE Audio hearing aids enable multi-stream audio streams in and out of the phone, each with its own set of controls. LE Audio offers "wireless calling, wireless music, wireless watching, and wireless calling" to its customers.

Figure. 6 LE Audio Hearing Aid

Consumer electronics products:

The audio source device (telephony/media audio): Because it enables multi-streaming, and LE audio source device can stream audio data to one or more sink devices.

LE audio source devices can be used on mobile phones, tablets, laptops, TVs, projectors, set-top boxes, streaming media players, and other devices.

The audio sink device (telephony/media audio) will receive audio data from one or more source devices. The multi-link capability provides for variable flow management depending on the demands of the user.

LE audio receiving devices include earbuds, headphones, and speakers, to name a few.

Figure. 7 LE Audio Source and Sink Device

Automotive and Industrial Industries:

Audio source/sink devices (telephony/media audio): The automobile industry is quickly transitioning to electrified vehicles (EVs). Current infotainment systems employ traditional Bluetooth for music and phone profiles, whereas LE Audio in infotainment will provide more functionality, such as audio sharing for music streaming and phone calls, while also consuming less power

Figure. 8 LE Audio in the Infotainment System

Location-Based Audio: Broadcast Audio is a great feature in LE Audio that can be used for a variety of purposes and reach a larger audience. Let's look at some examples of location-based audio:

Public Television: Libraries, waiting rooms, gyms, airports, railway stations, restaurants, places of worship, and other public televisions require public address or instruction audio delivery, which LE Broadcast Audio with multiple streams can help with.

Multilingual support: Different language translations for participants in different regions are required during seminars/conferences, and LE Audio Broadcast Multistreaming will give different language translations for different participants.

Users can sync their earbuds/headphones and hearing aids to pick language audio streams in cinemas, which require multilingual capability for various native language audio broadcasts.