2018/4/25 21:28:08
Bluetooth Low Energy

Bluetooth Low Energy (Bluetooth LE, BLE, formerly marketed as Bluetooth Smart) is a wireless personal area network technology designed and marketed by the Bluetooth Special Interest Group (Bluetooth SIG) aimed at novel applications in the healthcare, fitness, beacons, security, and home entertainment industries.Compared to Classic Bluetooth, Bluetooth Low Energy is intended to provide considerably reduced power consumption and cost while maintaining a similar communication range.


Mobile operating systems including iOS, Android, Windows Phone and BlackBerry, as well as macOS, Linux, Windows 8 and Windows 10, natively support Bluetooth Low Energy. The Bluetooth SIG predicts that by 2018 more than 90 percent of Bluetooth-enabled smartphones will support Bluetooth Low Energy.


Bluetooth Low Energy technology operates in the same spectrum range (the 2.400–2.4835 GHz ISM band) as Classic Bluetooth technology, but uses a different set of channels. Instead of the Classic Bluetooth 79 1-MHz channels, Bluetooth Low Energy has 40 2-MHz channels. Within a channel, data is transmitted using Gaussian frequency shift modulation, similar to Classic Bluetooth's Basic Rate scheme. The bit rate is 1 Mbit/s, and the maximum transmit power is 10 mW. Further details are given in Volume 6 Part A (Physical Layer Specification) of the Bluetooth Core Specification V4.0.


Bluetooth Low Energy uses frequency hopping to counteract narrowband interference problems. Classic Bluetooth also uses frequency hopping but the details are different; as a result, while both FCC and ETSI classify Bluetooth technology as an FHSS scheme, Bluetooth Low Energy is classified as a system using digital modulation techniques or a direct-sequence spread spectrum.

Technical specification

Classic Bluetooth technology

Bluetooth Low Energy technology

Distance/range (theoretical max.)

100 m (330 ft)

>100 m (>330 ft)

Over the air data rate

1–3 Mbit/s

125 kbit/s – 1 Mbit/s – 2 Mbit/s

Application throughput

0.7–2.1 Mbit/s

0.27 Mbit/s

Active slaves

7

Not defined; implementation dependent

Security

56/128-bit and application layer user defined

128-bit AES with Counter Mode CBC-MAC and application layer user defined

Robustness

Adaptive fast frequency hopping, FEC, fast ACK

Adaptive frequency hopping, Lazy Acknowledgement, 24-bit CRC, 32-bit Message Integrity Check

Latency (from a non-connected state)

Typically 100 ms

6 ms

Minimum total time to send data (det. battery life)

100 ms

3 ms

Voice capable

Yes

No

Network topology

Scatternet

Scatternet

Power consumption

1 W as the reference

0.01–0.50 W (depending on use case)

Peak current consumption

<30 mA

<15 mA

Service discovery

Yes

Yes

Profile concept

Yes Bluetooth Low Energy

Yes Bluetooth Low Energy

Primary use cases

Mobile phones, gaming, headsets, stereo audio streaming, smart homes, wearables, automotive, PCs, security, proximity, healthcare, sports & fitness, etc.

Mobile phones, gaming, smart homes, wearables, automotive, PCs, security, proximity, healthcare, sports & fitness, Industrial, etc.

Bluetooth Low Energy