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What is Bluetooth LE? What about testing Bluetooth devices?

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John Leonard, Tactical Marketing Manager at Nordic Semiconductor offered to post a blog entry on Bluetooth LE for readers to gain a better understanding of Bluetooth LE technology, what types ofapplications Bluetooth LE devices are best suited for, and what are some of the considerations as it relates to testing Bluetooth LE devices.  If you have any questions or comments you can post them at the end of this article and John will respond.

1. What markets and applications is Bluetooth LE designed to address?

A: In a nutshell, Bluetooth Low Energy is designed to address the needs of wireless applications that rely on batteries for their operation. More specifically, applications that typically need to operate from AA/AAA or even coin cell batteries. The range of such potential applications is vast but certain markets such as Sports & Fitness, Health & Wellness and Consumer Electronics are immediately recognisable. It also introduces the mobile phone into the mix, whereas previously all such wireless applications ran on a range of proprietary wireless standards it introduces a unified standard, now becoming present in just about every new smartphone release which allows the mobile phone to become a control center/hub to this huge range of applications

2. What are the key attributes of BT LE?

A: The key attributes to Bluetooth Low Energy are super-fast response times, a pre-requisite in real-time human interface applications. Additionally very low average power consumption demands typically under 200µA and peak current demands of 15mA or lower. Again, it is the first, tue low-power standard to be adopted by the mobile phone community which opens up many previously impossible scenarios.

3. How does it fit into the overall BT family?

A: Bluetooth Low Energy is an integral part of the latest Bluetooth v4.0 standard introduced in 2011. Bluetooth v4.0 encompasses all previously adopted functionality in Bluetooth. Therefore with Bluetooth v4.0 you have Basic Rate, Enhanced Data Rate and Bluetooth Low Energy within one specification. The devices that will support Bluetooth v4.0 will come in different variants, mobile phones will support all aspects of Bluetooth v4.0. Peripheral applications and products will often support only the Low Energy aspects of Bluetooth v4.0, this allows cost savings by removing features typically not of use in a peripheral application.

4. Which were the main companies involved in driving the standard?

A: Bluetooth Low Energy has its origins in a research study originally called Wibree between Nordic Semiconductor and Nokia dating back 6 years or more. Since these early beginnings many more companies have gradually become involved in developing the specification. A number of wireless semiconductor vendors are involved including CSR, TINordic Semiconductor is still a major contributor to standard developments and currently has one of its own Directors on the Bluetooth SIG Board of Directors.

5. How did Nordic become a the chair or the steering committee?

A: Nordic Semiconductor were invited to take a place on the Bluetooth SIG steering committee in order to bring specific ultra low-power expertise to the overall Bluetooth SIG decision making. Nordic Semiconductor as the market leader in 2.4GHz ultra low-power devices has a deep understanding of necessities and requirements for many of the peripheral application areas that Bluetooth Low Energy aims to support. These application fields include desktop peripherals for computers, Human Interface Devices (HID), Sports & Fitness and Helathcre/Wellness applications

6. What are the major technical  differences between BT LE, and other low power wireless technologies such as Zigbee?

A: There are many technical differences between Bluetooth Low Energy and Zigbee and it would be hard to cover them all here. The most significant are a different data rate, Bluetooth Low Energy has 1Mbs on-air data rate, Zigbee (using 802.15.4 PHY & LL standard) has 250kbs on-air data rate. Both wireless topologies operate in the licence-free 2.4GHz ISM band, Bluetooth Low Energy (2MHz channel width) identifies 37 separate communication channels, whereas Zigbee (5MHz channel width) identifies 16.  The two systems employ fundamentally different modulation schemes, Bluetooth Low energy uses GFSK whereas Zigbee uses OPQSK together with DSSS. Zigbee supports complex mesh networking, whereas Bluetooth Low Energy supports star-topology networks. The protocol behaviour of Bluetooth Low energy is specifically geared towards low latency, low power connections but implemented in as a ‘connectionless’ protocol which means devices do not remain connected when nothing is happening. The Zigbee protocol is oriented towards a connected monitored network, such as might be used in building automation.

7. What are seen as the major challenges/issues with testing BT LE?

A: The testing and qualification for Bluetooth Low Energy has been considerably simplified in comparison to previous Bluetooth qualification. In electrical terms testing a Bluetooth Low Energy product will require the requisite RF-capable testing tools that any wireless application would need, other than this there is no further complexity of note compared to any other wireless product testing. The qualification process allows for elements of self-certification allowing wireless platform designs to be re-used easily in various products assuming no changes are made to the RF hardware.

8. What guidelines does the SIG provide for the testing of BT LE enabled devices?

A: The Bluetooth SIG has specific guidelines on how to approach testing for Bluetooth Low Energy qualification. The Bluetooth organisation supply a Bluetooth Low energy Profile Tuning Suite, A Test Plan Generator in addition to supplying links to Bluetooth Qualified Experts (BQE’s) and Bluetooth Qualified Test Facilities (BQTF’s). It also details the requirements for qualifying and branding with the new Bluetooth Smart, and Bluetooth Smart Ready logos which enable consumers to identify types of product and associated functionality. These resources can be found at: www.bluetooth.org