Bluetooth® v5.1 Test Solutions

RF and Connectivity Tests for New Bluetooth v5.1 Standard with AoA/AoD Specifications

Following the worldwide popularity of smartphones, Bluetooth® technology has entered widespread use not only in smartphones but also in audio products, such as headphones and headsets, as well as in wearables and it has become one of the most successful radio technologies for general consumers. Today, Bluetooth is built into nearly every smartphone, tablet PC, and laptop.

The Bluetooth core spec v5.0 released in December 2016 extended the Bluetooth Low Energy (BLE) specification for ultra-low-power consumption as well as increased the data rate and communications range to promote easy use in wireless IoT, etc., systems. As a result, increased Bluetooth use is anticipated in wearables, wellness products, and industrial fields.

More recently, the updated Bluetooth core spec v5.1 (Bluetooth v5.1) released in January 2019 adds new functions increasing the convenience for IoT applications. Even prior to Bluetooth v5.1, the Bluetooth Low Energy feature of Bluetooth devices has been leveraged by location services using Bluetooth beacons . However, the accuracy has been relatively low and could not be estimated accurately at larger distances from the beacon. Bluetooth v5.1 solves this problem to achieve a high position location accuracy of just a few centimeters using a new Angle of Arrival (AoA)/Angle of Departure (AoD) directional search function.
As a result, Bluetooth v5.1 supports higher-quality location services and is expected to become increasingly common in various industrial fields.

(Source: Bluetooth SIG, Inc.)

Since this new AoA/AoD function is achieved using the Bluetooth signal PHY layer technology, a dedicated RF tester will be needed to confirm that the performance meets the Bluetooth v5.1 standard.

The Bluetooth® word mark and logos are registered trademarks owned by Bluetooth SIG, Inc. and any use of such marks by Anritsu is under license.

Potential Bluetooth v5.1 (AoA/AoD) Application Fields

Growth of position location services is expected in many fields and the higher positional accuracy offered by Bluetooth v5.1 AoA/AoD will support this growth. Some potential applications for Bluetooth v5.1 (AoA/AoD) technology are introduced below.

Warehousing

Bluetooth v5.1 location accuracy makes product warehousing easier because items can be found using a smartphone for more efficient working.

Parking

Vehicles with built-in Bluetooth v5.1 can be linked to a smartphone, making it easy to find a parked vehicle without remembering exactly where it was parked.

Shopping

Smartphone maps can display both the store location and the position of the item in the store, making it easier for shoppers to plan an efficient shopping route.

Viewing

Every time an art gallery visitor moves between pictures, the smartphone can display the route to next potential pictures for a better art appreciation experience.

What is Bluetooth v5.1 Angle of Arrival (AoA)/Angle of Departure (AoD)?

[Conventional Bluetooth Position Location]

Conventional Bluetooth position location technology compares the beacon power data with the actual Received Signal Strength Indication (RSSI) to estimate the position from the difference in the values. Although this method can estimate approximate distance from a beacon, it cannot determine the direction of the device from the beacon. Direction estimation requires installation of multiple beacons and high accuracy is still difficult to achieve.

(Source: Adding some words to Bluetooth SIG, Inc.)

[Bluetooth v5.1 Position Location Method]

The Bluetooth v5.1 position location method (directional search technology) compares the phase of radio waves received by multiple antennas built into the Bluetooth v5.1 device to calculate the angle of the arriving radio waves. There are two methods: Angle of arrival (AoA) and Angle of Departure (AoD).

Position Location Method	Explanation
Angle of Arrival (AoA) Multiple Rx Antennas	The radio waves sent from a beacon with one antenna are received by the multiple antennas of the receiver where the path of the arriving radio wave is switched to each Rx antenna to obtain the different phase information from each path. Note: To estimate the direction from the phase difference, the distance (d) between antennas must be within about 12 cm (one wavelength) so that the phase does not rotate a full 360 degree. (Source: Bluetooth SIG, Inc.)
Angle of Departure (AoD) Multiple Tx Antennas	The radio waves sent from a beacon with multiple antennas are received by the single antenna of the receiver where the arrival path to the Rx antenna is switched to match the distance between the Tx antennas to obtain the phase difference information. Note: Like AoA, the direction from the phase difference, the distance (d) between Tx antennas must be within about 12 cm (one wavelength) so that the phase does not rotate a full 360 degree (Source: Bluetooth SIG, Inc.)

A variable-length field called Constant Tone Extension defined newly in the Bluetooth Low Energy signal formats has been added to implement this Angle of Arrival (AoA)/Angle of Departure (AoD) function.
The power, frequency, RF characteristics, etc., measurements for this new added signal (frame) are determined by Bluetooth SIG and are supported by Anritsu’s MT8852B.

Bluetooth direction finding signal with CTE

(Source: Bluetooth SIG, Inc.)

Bluetooth Test Set MT8852B for Bluetooth v5.1

Since the new Bluetooth v5.1 AoA/AoD functions are achieved using Bluetooth signal PHY layer technology, to confirm that product performance meets the level specified by the Bluetooth v5.1 standard, a dedicated tester meeting the Bluetooth v5.1 test specifications is required by makers:

1. Developing Bluetooth v5.1 communications chipsets
2. Researching modules with built-in Bluetooth v5.1 communications chipsets
3. Researching devices with built-in Bluetooth v5.1 modules and chipsets.

Anritsu’s Bluetooth Test Set MT8852B is a dedicated Bluetooth measuring instrument meeting the requirements of the Bluetooth v5.1 test specifications and is approved by Bluetooth SIG as an industry-wide test solution.
With support for many test items, including Bluetooth chip/module/device RF tests and connectivity tests, the MT8852B has a wide application range in R&D and manufacturing processes.

Bluetooth Test Set MT8852B

The MT8852B Bluetooth v5.1 option supports the following Bluetooth v5.1 test cases and packet Tx functions.

MT8852B Supported Test cases

• Output Power
• Carrier frequency offset and drift
• Tx Power Stability, AoD Transmitter

MT8852B Supported Packet Generation

• AoA and AoD packet generation with slot duration and variable CTE lengths

Moreover, with the following features, the MT8852B is expected to help customers with early release of products for the fast-growing IoT market.

Anritsu as Bluetooth SIG Member

Anritsu is an active member of Bluetooth SIG creating international standards, including Bluetooth v5.1. The company uses this experience as well as strong customer partnerships to develop powerful measurement solutions.

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