Bluetooth Low Energy (BLE) is the fastest growing wireless protocol for short-range (<100 meters), low data-rate (<10 Mbps) applications. More than 3.5 billion Bluetooth devices will ship in 2017. Bluetooth is growing at least an order of magnitude faster than any of the other competing protocols like Zigbee, Z-wave, Thread, AllJoyn, IoTivity, ANT, WirelessHART, DigiMesh, EnOcean and others. This explosive growth is attributed to two factors:
- Apple’s choice to include Bluetooth radio in its iPhone and iPad product segments.
- Bluetooth Special Interest Group(SIG) has aggressively updated the BLE specifications to match the evolving needs of this huge market.
The result is Bluetooth radios are ubiquitous in consumer electronics segment. The numbers below are from Bluetooth SIG website:
Are wireless protocol wars over?
Last few years has witnessed an intense battle between short-range ISM band wireless protocols. There are many good online comparisons of the technical merits of each protocol. No protocol is perfect and there is no requirement that all applications use the same protocol. Many legacy applications will continue to use their existing protocols as the cost of retrofit is too high.
For many applications, the small differences and advantages in the technical features of their favorite protocol will not be sufficient to overcome the business, cost and interoperability advantages of the “popular” protocol. In terms of popularity, Bluetooth is the clear winner, and this is one area where network effect will accelerate its dominance. The newly released version 5 of the Bluetooth specification is designed to cement the leadership position of this protocol. This post summarizes some of the key highlights from the 2800 page Bluetooth 5 core specification published by the Bluetooth SIG.
New features of Bluetooth 5.0
The most important features are:
- speed increase
- range increase
- New advertising modes
Speed increase - The new 2 Mbps option
The bottom layer of the Bluetooth stack is called the physical layer or the PHY. Bluetooth 4.x specification called out the 1 Mbps PHY. The 5.0 version adds the 2 Mbs (LE 2M) option. To use this new capability, the both radios in the link must support the 2Mbps rate. Together, with Data Length Extension (DLE) feature that was announced in Bluetooth 4.2, the new PHY will increase the speed and the amount of data that can be transferred over a BLE 5.0 link. For devices that do not require higher data rates, the 2Mbps link will offer an advantage in terms of power consumption, as these devices will require half the time complete a wireless transaction. There is also an additional benefit where packing the data at 2Mbs will increase the network capacity as all devices have to share the same wireless medium. This new mode will enable applications like medical ECG, voice-remotes, still-image transfer, power-efficient beacons, etc.
Range increase - The new coded PHY option
In addition to standard 1Mbps and 2Mbps options, Bluetooth 5.0 offers the 500 Kbps and 125 kbps options, also called the coded-rates. Both the coded-rates use the underlying 1 Mbps PHY. In case of the 500 kbps options, two bits of 1 Mbps stream is used encode 1 bit of 500 kps data. In case of 125 kbps, 8 bits of 1 Mbps stream is used to encode 1 bit of 125 kbps data. This encoding scheme uses Forward Error Correction (FEC) technique to create a wireless signal with higher Signal-to-Noise Ratio (SNR). In case of 500 kbps stream, the range is doubled and for 125 kbps, the range is quadrupled. In both the case, the increased range is achieved without increasing the radio transmitter power. With this new range options, Bluetooth LE provides credible options for enterprise and industrial IoT deployments. The capability to switch between fast connections and long range will protect investment in the Bluetooth technology stack. It is important to note that it is not possible to obtain the higher 2x speed and 4x range simultaneously.
New advertisement modes - advertisement extensions
Bluetooth LE connectionless mode is very popular with applications like beacons and sensors. The connectionless mode uses Bluetooth advertisement channels to broadcast data to any Bluetooth radios that are in the scanning mode. With BLE 4.x, all the advertisements are transmitted on 3 channels (out of 40 total channels). The new advertisement extensions expand these capabilities significantly:
- Increased channel capacity: To increase payload capacity without clogging the advisement channels, BLE 5.0 can start advertisements in the standard channels and complete the data transfer on an agreed upon non-advertising channel.
- Increased payload size: Up to 255 bytes of data can transferred in non-advertising channel.
- Payload chaining: Advertising packets can be chained together to create large beacon payloads. A chain can hold a maximum of 1650 bytes.
- Periodic advertisements: Advertising packets can be sent periodically, allowing observers to lock on to a stream of advertised packets.
Impact of Bluetooth 5.0 specification
Bluetooth 5.0 is a major update to the wireless standard. Many Bluetooth applications that were operating on the feasibility edge (in terms of range or data throughput) are now fully supported. Previously, some applications used a Bluetooth radio to support short-range communication and a sub-1-Ghz radio for long distance communication link. With BLE 5.0, communications links is dramatically simplified by using a single technology stack
The current Bluetooth mesh technology is based on broadcast capabilities provided by the BLE 4.x standard. With the new advertisement extensions, it is expected the BLE mesh will also be revised to exploit the new capabilities. BLE 5.0 will enable further penetration in home and building automation, industrial IoT and in healthcare applications. The latest generation smartphones are starting to support the new Bluetooth 5.0 features. It will take a few years for this change to occur. For many applications, using a Bluetooth edge gateway will be the fastest route to harness the full power of the Bluetooth 5.0 specification.