ALLPCB
Introduction
As smart devices proliferate, wireless communication standards that enable devices to exchange data over short and long distances are central to personal area networking. Bluetooth is one of the most commonly encountered wireless technologies in consumer connected devices.
Generational overview
Classic Bluetooth originally offered data rates around 1–3 Mbps with typical ranges of about 10 m to 100 m. High Speed Bluetooth (Bluetooth HS) increased throughput up to roughly 24 Mbps. Bluetooth Low Energy (BLE or Bluetooth LE) targeted low power use, with common data rates around 1 Mbps and typical ranges near 30 m. The main differences between Bluetooth versions relate to data rate, range, power consumption, and supported features.
Bluetooth 1.x and 2.x
The initial 1.0 specification published in 1999 provided data rates near 748–810 kbps, was susceptible to interference from co-frequency devices, had interoperability issues across vendors, and offered limited pairing security. Bluetooth 1.2 improved pairing speed and added adaptive frequency hopping to reduce interference with other wireless technologies.
Bluetooth 2.x introduced non-hopping narrowband channels that enabled transmission to multiple devices and enhanced security and pairing. Version 2.1 expanded query and pairing features and added power-saving modes such as Sniff Subrating, which allows devices to negotiate longer intervals between confirmation signals to reduce power consumption.
Bluetooth 3.0
Bluetooth 3.0 introduced an optional High Speed mode that leverages Wi-Fi for bulk data transfer, achieving theoretical rates up to 802.11 Mbps and effective Bluetooth HS rates around 24 Mbps while reducing energy consumption compared with earlier implementations.
Bluetooth 4.x: Low energy focus
As smartphones, laptops, automotive systems, and wearable devices expanded into IoT and medical applications, demand for lower power consumption increased. Bluetooth 4.0 emphasized low-power operation while supporting three profiles: classic Bluetooth, high speed, and low energy. Key capabilities included lower cost, cross-vendor interoperability, low latency (on the order of milliseconds), AES-128 encryption, and extended range to 50–100 m in many implementations. Bluetooth 4.x enabled use cases such as fitness trackers, medical monitors, sensors, and home automation devices.
Bluetooth 5.x and beyond
Bluetooth 5.0, released in 2016, added a 2 Mbps "high speed" PHY and long-range modes at 125 kbps or 500 kbps, extending effective range to up to about 300 m in ideal conditions and improving battery life. These features enable indoor positioning and navigation scenarios; combined with Wi?Fi, submeter indoor positioning is possible. Bluetooth 5.0 also expanded broadcast capacity and support for more complex connection topologies such as beacons and location services, allowing some data to be delivered without explicit pairing.
Bluetooth 5.1 added enhanced location features and was the first to add support for Angle of Arrival (AoA) and Angle of Departure (AoD), enabling devices to determine directionality for positioning and faster, lower-power connections. Bluetooth 5.2 introduced LE Audio, which runs over Bluetooth Low Energy and uses the LC3 codec (Low Complexity Communication Codec). LE Audio enables multi-stream audio and allows multiple headsets to share the same audio source.
Bluetooth 5.3 introduced additional improvements, including LE Coded PHY for extended range, increased data rate up to 2 Mbps, and enhancements to wall penetration. It also added low-rate modes and periodic advertising enhancements to reduce packet loss and power consumption for IoT endpoints such as smart bulbs and wearables. Bluetooth 5.3 also enforces minimum encryption key sizes for connections, improving security by preventing connections when a peer cannot provide a sufficient key.
LE Audio, Auracast, and audio features
LE Audio (standardized in 2020) leverages the LC3 codec to provide improved audio quality at lower power. It supports audio sharing and includes features to improve accessibility for hearing-impaired users, such as better support for hearing aids. LE Audio also defines Auracast, a broadcast audio model that enables one-to-many audio distribution without pairing. Auracast allows listeners to tune into broadcast audio streams in public settings, for example choosing a muted TV feed at a bar or selecting among multiple simultaneous broadcasts without latency during switching. Devices that support Auracast can scan, join, and listen to broadcast streams when available.
Technical updates in recent versions
Bluetooth 5.2 introduced three notable updates: EATT (Enhanced Attribute Protocol) to allow more concurrent, lower-latency attribute transactions with improved security; LE Isochronous Channels to support synchronized timing for one-to-many audio streams under LE Audio; and LE Power Control for dynamic transmit power adjustments to improve link stability and reduce power consumption.
Auracast and LE Audio are integrated into the core LE specifications since Bluetooth 5.2, enabling password-protected shared audio sessions (for example, sharing a laptop or phone audio to multiple headsets) similar to establishing a private Wi?Fi hotspot.
Market trends and use cases
The Bluetooth SIG 2023 Market Trends Report indicated steady growth in Bluetooth device shipments, projecting about 7.6 billion units by 2027 with a compound annual growth rate of approximately 9%. Future directions highlighted by the SIG include wider bandwidths, support for higher frequency bands (including 5 GHz and 6 GHz), and improved location accuracy.
Industry collaboration among device makers and semiconductor vendors has produced specifications aimed at gaming and low-latency audio. For example, several vendors have cooperated on a Gaming Audio Profile 1.0 to reduce latency for live-streamed and interactive audio applications. Major vendors have also demonstrated LE Audio and Auracast concepts and compatibility in prototype products.
Summary of trends
- Greater focus on low power and low latency to support IoT, wearables, and audio devices.
- Expanded range and throughput options through new PHYs and coded modes.
- Native support for LE Audio with multi-stream capability, improved codecs, and broadcast audio (Auracast).
- Enhanced location services via AoA/AoD and improved periodic advertising for IoT use cases.
- Ongoing improvements in connection security, power control, and synchronization for multi-device audio.
