The Bluetooth Special Interest Group (SIG) has officially adopted a new version of the Bluetooth core specifications. Version 4.2 promises greater speed, greater privacy, and a soon to be ratified Bluetooth profile for IP connectivity. With the Internet of Things (IoT) revolution underway, the Bluetooth SIG hopes that these new capabilities for the wireless standard will help Bluetooth’s personal area networks be an enabler for IoT going forward.

Bluetooth is already in many devices and is favored in mobile and wearables due to its low power profile. Battery life in wearables is critical for user experience, and as we have seen the technology for wearables is in its infancy right now. Power use will be critical, due to the limited amount of space available, so Bluetooth 4.2 will extend the features of Bluetooth Low Energy to allow low-power IP connectivity over Bluetooth with a new profile which supports IPv6 and 6LoWPAN, which is low power wireless personal area network over IPv6. Bluetooth devices will then be able to directly access the internet through an edge device, rather than have to be tethered to a smartphone or other device with IP connectivity first.

The group is also adding some privacy features to the new spec. Currently, Bluetooth Beacons can be utilized as a way to track people. For example, a department store may implement beacons to track customer movements throughout the store. While it may be well meaning, these sorts of technologies may give the feeling of an invasion of privacy, so the new 4.2 spec will allow the MAC address of Bluetooth devices to be masked unless connecting to a trusted device. At the same time, the new devices will have additional refinements to reduce power consumption as part of the Low Energy Privacy 1.2 specifications.

Microsoft Band - a Bluetooth tethered wearable

Finally, Bluetooth LE will see a speed increase, with packet capacity increasing by 10 times, and overall speed increasing by 2.5 times over previous implementations. Standard Bluetooth packets offer a payload maximum of 1021 bytes. With the new specification, there are some additional header fields and a trailer added to the packet to allow for additional payload per packet. The maximum data transfer of Bluetooth Basic Rate (the original 4.0 spec) is about 2.1 Mpbs, and Bluetooth LE can only achieve 260 kbps. The increase is targetted towards the LE spec only, which should increase the maximum theoretical speed to 650 kbps. Real world use will not achieve the full speed increase, but the Low Energy Data Length Extension will be a welcome addition to the specification as more and more devices gain connectivity. Astute readers who follow Bluetooth may realize that Bluetooth 3.0 added capability for up to 24 Mbps, but that involves using Bluetooth to negotiate a connection over Wi-Fi. For devices with a Wi-Fi radio and the power capacity, this may be a better method if high speed data is required, but if the transfer is done over Bluetooth exclusively then it should use less power.

Bluetooth Maximum Transfer Rates (kbps)
Type Symmetric Transfer Asymmetric Forward Transfer Asymmetric Reverse Transfer
DM1 108.8 108.8 108.8
DH1 172.8 172.8 172.8
DM3 258.1 387.2 54.4
DH3 390.4 585.6 86.4
DM5 286.7 477.8 36.3
DH5 433.9 723.2 57.6
AUX1 185.6 185.6 185.6
2-DH1 345.6 345.6 345.6
2-DH3 782.9 1174.4 172.8
2-DH5 869.1 1448.5 115.2
3-DH1 531.2 531.2 531.2
3-DH3 1177.6 1766.4 235.6
3-DH5 1306.9 2178.1 177.1
Bluetooth LE 260
Data Packet Length Extension(4.2 spec) 650

The Bluetooth SIG has a good reason to want to get in on the IoT movement. An estimate by the Harvard Business Review, which draws on Goldman Sachs research, estimates that by 2020 there will be 28 billion connected devices on the internet. That is a big pie, and with the existing number of devices with Bluetooth already, as well as the robust encryption Bluetooth uses, the new specifications should help drive devices to using Bluetooth as their connectivity of choice.

There are of course other competing technologies for connecting IoT devices, with the obvious one being Wi-Fi with backers such as the Thread Group. There are advantages to some of these competing technologies as well such as Mesh networking, which is not part of the new Bluetooth spec. CSR has added their own extensions to Bluetooth which do allow mesh networking, but as it is not part of the official spec it will make it harder to be relied upon.

The Bluetooth specifications have an advantage though in that they will not necessarily require new hardware. Many of these features can be added via software updates because the existing radio technology is not changing. The group has a list of “Bluetooth Smart” devices that it keeps on its website.

Source: Bluetooth SIG

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  • prithvirajnarendra - Thursday, December 4, 2014 - link

    An application can achieve a data rate of 100 kbps in the state of the art devices using BLE. Usually it is lesser than this. The theoretical maximum data rate was 236.7 kbps with BLE (v4.0 and v4.1). With v4.2 this would increase by 2.5 times. This is because the maximum payload in the link layer is increased from 39 octets to 257 octets, which increases the amount of 'useful' data sent per packet.
  • Brett Howse - Thursday, December 4, 2014 - link

    You're correct I pulled the numbers from the spec but they are obviously for standard Bluetooth. I'll update the info thanks!
  • sweetca - Thursday, December 4, 2014 - link

    The "Nerd" is strong in this one.
  • prithvirajnarendra - Thursday, December 4, 2014 - link

    Well, that's my Master thesis talking. Can't let a site like AnandTech post completely wrong data.
  • reininop - Friday, December 5, 2014 - link

    And that is why I come here. The comments are nearly as informative as the reviews.
  • hsingh - Tuesday, December 16, 2014 - link

    Out of the 39 bytes (v4.1) and 257 bytes (v4.2), how many are the data bytes to calculate the effective data throughput of 236.7kbps(v4.1) and 650kbps (v4.2).
  • HisDivineOrder - Thursday, December 18, 2014 - link

    Funny how security didn't become a big issue until a certain leak exposed how rampantly privacy was being run ramshod over. Suddenly, it's everywhere. Even in wireless connection specs meant to enable connecting to public devices.

    I'm not complaining about the shift in attitudes, but it's interesting to see how the attitude about enabling "security" features against large entities being able to track you have shifted in such a short time.

    I guess that's what the NSA did for us. If they hadn't overreached, they wouldn't have proven to people that gross overreach was inevitable.
  • benzosaurus - Saturday, December 20, 2014 - link

    Now if they could just figure out how to make Bluetooth reliably negotiate a connection anytime ever, we'd be all set. I'm really not looking forward to a world where Bluetooth is used for anything other than cheap headphones and mice.
  • tazaguru - Monday, June 1, 2015 - link

    Good information. Thanks. Qs, We are thinking about replacing all our Keyboard and mousing to wireless , at the same time, making sure that the key taps are not hijacked with MIM attacks or such. BT 4.2 qualifies for this requirement but does anyone know if Windows/MAC (maybe linux too) support this? If yes, any timeline would be very helpful. Thanks

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