Bluetooth low energy

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Bluetooth Low Energy , Bluetooth LE ( BLE for short) or Bluetooth Smart is a radio technology that can be used to network devices within a range of around 10 meters (see also computer network ). Compared to “classic” Bluetooth , BLE is said to have significantly lower power consumption and lower costs with a similar communication area. Technically, Bluetooth Smart is not backwards compatible; newer Bluetooth devices must also support the LE protocol stack in order to be able to connect.

Since December 2009 this extension has been added to the Bluetooth industry standard , published as an optional part of Specification 4.0. Before the integration, radio technology was also known as Bluetooth ultra low power or Wibree . With the Bluetooth specification 4.2, IPv6 was integrated into the smart protocol stack in order to better position the technology for the Internet of Things . Bluetooth 5.0 only includes changes for low energy with new modes for building automation , for which a mesh protocol was added later. With Bluetooth 5.1 as an update to Bluetooth 5 , centimeter-accurate location was introduced in 2019.

history

Nokia started the development in 2001 to fill gaps in the previous application scenarios. The Bluetooth standard of the time was used as the basis (Bluetooth 1.1 standard 2002 and Bluetooth 1.2 standard 2005), which was further developed for lower power consumption and costs. The results were first published in 2004 as a research project at the IEEE as "Bluetooth Low End Extension". With other partners in the 6th FP of the EU , the service side was further defined by the MIMOSA project, and the results were presented in October 2006 under the trademark “Wibree”. The name “Wibree” is made up of “Wi” as an abbreviation for wireless and “Bree” after a place from the fantasy saga Lord of the Rings where important paths cross. At the time, Wibree was a joint development by Nokia , Logitech, Epson , Broadcom, CSR and Nordic.

In June 2007 an agreement was reached between the Wibree forum and the Bluetooth Special Interest Group , with which the Wibree technology should be included in the Bluetooth standard. In the first announcements of the part of the standard to be developed in July 2007, the radio technology was then called Bluetooth Ultra-Low-Power Technology. This was renamed again before it was completed, as the term Ultra Low Power used has a linguistic association with power, which should be avoided in view of the political demand for devices with lower energy consumption. The new protocol architecture was then presented as Bluetooth Low Energy in April 2009 in Tokyo. The formal adoption of Bluetooth 4.0 as part of the standard took place in December 2009.

Bluetooth 4.2 was adopted in December 2014 and contains numerous enhancements for the Bluetooth Smart area. In addition to the support of IPv6, there is also the option of sending data packets ten times as long via the channels. There are also improvements to the security architecture, as the old procedures could be bypassed. The wearables available since 2015 therefore communicate continuously via Bluetooth 4.2.

Bluetooth 5.0 was released in December 2016. Significant innovations are the double transmission rate with BLE of now 2 Mbit ( 2M PHY ) or the reduction of the data rate (to 500 or 125 kbit) in favor of the range ( LE Coded ). Where permitted, BLE is now allowed to transmit at 100 mW instead of 10 mW as in the previous standards.

Bluetooth 5.1 was released in January 2019. "Direction Finding" / a form of radio direction finding was introduced as a major innovation . This not only makes it possible to determine the approximate distance from the reported signal strength, but also from which direction a signal was sent. Using triangulation , it is possible to locate the system in the centimeter range, which is particularly advantageous within buildings, but can also support pedestrian navigation. In addition, the parallel developed Bluetooth mesh protocol was integrated.

Bluetooth 5.2 was released in January 2020. The main innovation here is a new audio profile ("LE Audio" for short). This is also based on the introduction of isochronous channels for stable transmission. There was already Bluetooth audio from various manufacturers via Bluetooth LE before, but since the Low Complexity Subband Codec (SBC) was used as standard for compression in the A2DP profile of Classic Bluetooth , 4 proprietary codecs dominated the market for Bluetooth because the free SBC codec was 48 kHz results in a data rate of 345 kBit / s, which is higher than the uncoded LE data rate. Even then, interference could lead to dropouts that could only be absorbed by the higher net data rate of the 2M PHY at a shorter distance. With Bluetooth 5.2, the Low Complexity Communications Codec (LC3) is now being introduced as a basic standard, which compresses better and covers a range from 16 to 320 kBit / s with various sampling rates. The aim is that the bit rate of the transmission decreases with increasing distance from the base device and the audio quality also decreases accordingly without producing audible dropouts, as was usual with SBC variants.

Logos

A separate Bluetooth Smart logo was created for Bluetooth LE technology . Devices with this logo can only connect to other Bluetooth Smart or Bluetooth Smart Ready devices.

The Bluetooth Smart Ready logo can be found on conventional Bluetooth devices (e.g. smartphones) that have been expanded to include Bluetooth LE technology. These can connect to the "classic" Bluetooth devices and to Bluetooth Smart or Bluetooth Smart Ready devices. This is made possible by two different radio units.

These marketing terms have since been abandoned.

compatibility

Bluetooth Smart and Bluetooth Smart Ready are optional components of Bluetooth 4.0. One consequence of this is that Bluetooth 4.0 devices do not necessarily have to be able to communicate with Bluetooth Smart devices. Devices in Classic Bluetooth generally only have to support cooperation ("connectivity") with the basic speed BR (Basic Rate), transmission with EDR (Enhanced Data Rate), HS (High Speed) or LE (Low Energy) is optional. For Bluetooth Smart One is single-mode -Implementation provided, which knows only the connectivity by LE.

Both Classic Bluetooth and Bluetooth Smart work in the 2.4 GHz ISM band , so they can share one antenna. The radio transmission for LE differs so much that different integrated circuits are regularly used for implementation, which are addressed separately on the software side, even if they are integrated in the same chip.

Through the processing of the Bluetooth standards committee and the historical derivation of the low-energy process from conventional Bluetooth, interference-free parallel operation of classic Bluetooth and Bluetooth Smart devices is guaranteed. The methods used for collision avoidance and bit transmission are similar.

Bluetooth 5

In the specification of Bluetooth 5.0, the term Smart was no longer used. Instead, the Bluetooth 5 designation will be introduced without versioning and will remain the same for Bluetooth 5.1 (which includes expansions for centimeter-accurate location). Backward compatibility with Bluetooth 4 and its 1M PHY is mandatory. Since all innovations in Bluetooth 5 relate exclusively to Bluetooth LE, Smart compatibility can be assumed.

Radio transmission

Bluetooth LE divides the ISM frequency band into 40 channels with a width of 2 MHz. (Conventional Bluetooth BR / EDR divides the ISM frequency band into 79 channels with a width of 1 MHz). Like Bluetooth BR, Bluetooth LE uses an FH-SS frequency hopping method to avoid collisions, and both use GFSK frequency shift keying for bit transmission. The alternative phase shift keying in the modulation provided for the higher-throughput EDR transmission from Bluetooth 2.0 onwards are not used by Bluetooth Smart , so that pure BLE chips can be structured more simply.

The data transfer rate with Bluetooth LE is 1 Mbit / s, identical to the value of the Basic Rate BR. A maximum transmission power of 10 mW is provided for Bluetooth Smart devices, so that the typical range is 40 meters. The Bluetooth standard also includes class 1 Bluetooth devices that can transmit at 100 mW (typical range of 100 meters). This was recorded using the Bluetooth 5 standard for Smart Profiles. Silicon Laboratories presented a BLE SoC at the end of 2016 , which should achieve a range of up to 200 m. However, this transmission power is usually not used with Bluetooth Smart to save energy.

The procedures for error correction and connection establishment are significantly different from classic Bluetooth. The net data rate drops from a maximum of 0.7 Mbit / s ( basic rate ) to 0.27 Mbit / s, a connection can be established in 3 ms instead of at least 100 ms, and data transfer can be completed after 6 ms. In particular, the short bursts on the radio link contribute to the low power consumption of Bluetooth LE devices: Instead of 1000 mW as a reference with conventional Bluetooth, there are Bluetooth Smart profiles with a power consumption of typically 10 mW.

2M PHY

With Bluetooth 5, the previous radio transmission has been expanded to include a mode with double symbol rate. Since with LE only one 1 bit is transmitted per symbol, the maximum data rate is theoretically doubled. However, the new mode also increases the bandwidth from around 1 MHz to around 2 MHz, so that more interference occurs in peripheral areas. The division of the ISM frequency band into 40 channels with a width of 2 MHz has not been changed. This is an essential difference to Bluetooth 2 EDR, which was also able to double the bit rate, but achieved this on 1 MHz bandwidth using π / 4-DQPSK and 8-DPSK phase modulation , while Bluetooth 5 remains with a pure GFSK frequency shift keying.

The previous radio transmission with 1 Mbit analogous to the Bluetooth Basic Rate was renamed with Bluetooth 5 in 1M PHY. The transmission with double step speed was newly introduced as 2M PHY. Every connection in Bluetooth Low Energy begins with a 1M PHY and it is the task of the application to request a switch to a 2M PHY. Both sides then switch between sending and receiving. The switch to the 2M PHY is intended primarily for firmware updates, in which the application makes a new attempt with the traditional 1M PHY if it fails. The target device should be close to the transmitter (a few meters).

LE Coded

With Bluetooth 5, the previous radio transmission has been supplemented by two modes with a reduced data rate. The symbol rate of the "Coded PHY" corresponds to the 1M PHY, but with mode S = 2 always two symbols are used per data bit. The coding pattern P = 1 ("Pattern Mapping") used for S = 2 is very simple - the same symbol is produced for each data bit to fill in. In the mode S = 8 with eight symbols per data bit, however, one data bit is coded in opposite directions - with the coding pattern P = 4, a 0 is coded in binary 0011 and a 1 in 1100 is binary coded. At S = 2 with P = 1 the range is roughly doubled, at S = 8 with P = 4 the range is roughly quadrupled.

With the "LE Coded" transmission, however, not only the error correction is changed, but a fundamentally different packet format is used. An “LE Coded” burst consists of three blocks. The switchover block (“extended preamble”) is transmitted like an LE 1M PHY, but only consists of 10 binary '00111100' in a row. These 80 bits are not recoded by the usual error correction of LE, but appear directly in the radio channel. This is followed by a header block (“FEC Block 1”), which is always transmitted with S = 8 and only contains the target address (“Access Address” / 32 bit) and the coding identifier (“Coding Indicator” / 2 bit). The coding identifier indicates the coding pattern with which the following useful data block ("FEC Block 2") is transmitted - S = 2 can then be used here.

The new packet format of Bluetooth 5 allows from 2 to 256 bytes to be transmitted as user data in one burst. This is considerably more than the previous maximum of 31 bytes of user data with Bluetooth 4. Together with the range detection, this should be sufficient for localization functions. In total, four times the range - with the same transmission power - is bought at an eighth of the data rate of 125 kBit. The old packet format, which is still used with 1M PHY and 2M PHY, is now called "Uncoded" from Bluetooth 5 onwards. In between there is the “LE Coded” S = 2 format with 500 kBit for the user data, which can reduce latencies in particular and is more energy-efficient with long data blocks because the overall burst is shorter.

Connection types

The Classic Bluetooth can manage up to 255 devices (slaves) in the piconet, 7 of which can be active at the same time and share the bandwidth (with EDR, up to three audio transmissions can take place in parallel without interference). The Bluetooth Smart does not recognize an active / passive distinction (it is also not suitable for audio transmission).

All Bluetooth LE devices send short advertising events (attention notices) independently of one another on one of the three advertising channels (effectively registration channels). The device then listens on this channel for a connection request, whereupon it switches to one of the remaining 37 channels in order to receive a larger data block from the device. With Bluetooth Smart , the possible master is passive most of the time, the possible slaves send at regular intervals on the advertising channel - as an example, the iBeacon can be configured so that it is only active every 900 ms instead of 100 ms. The distinction between master and slave is not generally assigned to the devices involved, but whoever reacts to an advertising event becomes the master for the following data connection.

Connection establishment

While the radio transmission and the connection establishment of Bluetooth LE are incompatible with the remaining parts of Bluetooth, the higher parts in the Bluetooth protocol stack use the same protocols (L2CAP, ATT). The problems of the Bluetooth security modes have also been carried over.

To establish initial contact between two devices, a device periodically sends packets on at least one of the three advertising channels. The other device listens periodically on one of the three channels for a specific period of time, with the channel being changed after each interval. The procedure is successful as soon as a packet falls into a reception phase. The two periods for sending packets ( advertising interval ) and for receiving them ( scan interval ) as well as the duration of a receiving phase ( scan window ) can be freely selected by a device within certain limits. The choice of parameters has a strong influence on the latency and energy consumption of the connection setup.

After the first contact has been made, the parameters for frequency hopping are also set, which is simply the time spent on a channel ("hop interval") and the grade value to the next channel ("hop increment"). With Bluetooth LE, a packet must be transmitted on each channel, and then the channel must be changed. Each packet begins with an 8-bit Bluetooth LE identifier, followed by a 32-bit access identifier, in front of the maximum 39 bytes of user data and a 24-bit checksum . Since the user data in the protocol stack always contains a length field (often with a value of zero) and bits for data flow control (14 bits in total), the user data area is effectively at least 2 bytes long. The access identifier is specified on the advertising channel (hexadecimal 0x8E89BED6), and an identifier that was specified when the connection was established is used on the 37 data channels.

In fact, the access code is already in the “connect package” on the advertising channel; this simplifies the passive listening in of data in the radio channel. Since the encryption information for the AES-CCM algorithm is also provided when the connection is established, attackers can understand the data. Further protection mechanisms, such as the assignment of a six-digit PIN, are not used in practice - all values ​​in the standard have the value zero in reality. With Bluetooth 4.2, the weak points in “pairing” have also been eliminated with the newly introduced ECDH (Elliptic Curve Diffie Hellman).

Profiles

From the perspective of Classic Bluetooth , Bluetooth LE devices always connect via the GATT profile - the Generic Attribute Profile is optimized for sensor data and, in general, the energy-efficient transmission of small amounts of data. In addition to access control via GAP ( Generic Access Profile ), single-mode Bluetooth Smart devices only implement variants of this profile. The GATT specification defines a number of attributes and shows the use for sensor profiles and application services; GATT specification 1.0 already contained two dozen GATT profiles and services. In principle, a Bluetooth Smart device can assume several roles at the same time and offer them in the advertising event .

Bluetooth LE supports practically none of the common Bluetooth profiles such as the connection of a headset (HSP profile) or the transmission of audio and video ( A2DP and VDP profiles ). There is no equivalent support for this within the GATT profiles. The Bluetooth profile FTP for file transfer is a superset of the OBEX profile (Object Exchange), which can be found in Bluetooth LE in the GATT profiles OTP and OTS (Object Transfer Profile / Service).

equipment

Like Bluetooth 2.1, Bluetooth Low Energy transmits in the 2.4 GHz range, should consume less energy and be significantly cheaper to integrate. This new protocol stack is compatible with Bluetooth version 2.1, but can be configured independently. Bluetooth Low Energy will be available as a single-chip solution for small devices and can be used in combination with previous Bluetooth devices. At least one new software version is required for previous devices.

The Android operating system supports Bluetooth Low Energy from version 4.3 (mid-2013). Apple's iOS operating system has been supporting BLE since iOS 5 with the CoreBluetooth framework, which was released in October 2011. BLE is already available for the Nokia Lumia 520, 620, 625 and 720 with the Lumia Amber software (mid-2013). With the software update to Nokia Lumia Black (early 2014), the Bluetooth LE function was activated on all Nokia Lumia smartphones with Windows Phone 8.

In addition to Windows Phone 8.1, there is also support from the Windows 8 desktop operating system. Under Linux, support is found in BlueZ 5, which was introduced at the beginning of 2013 and requires at least a 3.4 kernel. There is also support from BlackBerry 10 and Unison OS 5.2.

Bluetooth 5.x

Bluetooth 5 has been supported since Android Oreo (8.0) . This led to some confusion when the Samsung Galaxy S8 was released , which brought hardware for Bluetooth 5.0 with it, but couldn't use it at all thanks to Android 7. It was also shown that this device allows the 2M PHY for a higher data rate, but not the LE Coded mode for a higher range.

Bluetooth is 5 for iPhone 8 / iPhone X supported. A suitable chip has been built into the MacBook Pro since 2018. However, headphones with Bluetooth 5 are only available with Apple's second generation AirPods .

Bluetooth mesh

The mesh protocol for Bluetooth is developed independently of the standardization for Bluetooth devices, but requires at least one LE connection, as has been integrated since Bluetooth 4.0. The development of "Bluetooth Mesh" began in 2015, and version 1.0 was approved by the Bluetooth SIG in July 2017.

Bluetooth mesh works with short messages that are often less than 11 bytes long and can contain up to 384 bytes. Fragments can be sent in different bursts and are reassembled at the destination; from Bluetooth 5, the long messages also fit into a single burst ( LE Coded can transmit 256 bytes in one burst instead of a maximum of 31 bytes of payload previously).

A message always begins with the opcode, which can contain 1 byte (special messages), 2 bytes (standard messages) or 3 bytes (manufacturer-specific special messages). Also included are the source address and destination address in the network, which can affect both individual and groups of devices. The sequence number used avoids replay attacks. Encryption and authentication are mandatory, with different keys being used for the network and application.

The TTL (time to live) as a message field is limited to 126 hops. A maximum of 4096 sub-networks can be linked, with which a maximum of 65535 scenes can be addressed. Theoretically, a maximum of 16384 groups with a maximum of 32676 nodes each can be addressed there, but a lower limit is expected in practice.

Others

Corona apps

In the course of the COVID-19 pandemic , a number of apps for smartphones were released to facilitate the social tracing of contacts of infected people. The automated collection of contacts often takes place via Bluetooth Low Energy, the most common form of local radio in the population. This results from the design of Bluetooth for a wireless personal area network with a range of a few meters at most. Other short-range radio standards such as NFC have a range that is too short, while other radio standards available on smartphones have higher power consumption.

When apps were published, data protection issues arose in mid-2020. Activating the Bluetooth signal strength requires the "location determination" access right in the settings, which also allows access to other location services, including GPS. This is related to Bluetooth radio beacons or Apple's iBeacon , which were designed for indoor navigation systems , where you can still send the exact geo-coordinate to the smartphone in the absence of the GPS signal. A real-time triangulation of several beacons is then even possible to determine with centimeter accuracy. The use of this location determination, as well as GPS, is denied by the manufacturers of the apps. However, when the apps were put into operation, the operating system manufacturers for smartphones did not offer any technical means of distinguishing between distance measurements and coordinate services with different access rights. This technical restriction is to be distinguished from demands to record the locations of the contacts in order to reduce false alarms during containment.

See also

Web links

Individual evidence

  1. ↑ SIG Introduces Bluetooth Low Energy Wireless Technology, The Next Generation of Bluetooth Wireless Technology. In: SIG Press Releases. Bluetooth Special Interest Group (SIG), December 17, 2009, accessed January 28, 2010 .
  2. ↑ Nico Jurran: Bluetooth gets mesh network: competition for networking is getting fiercer. Heise Verlag, July 18, 2017, accessed on May 13, 2020 .
  3. ↑ a b Andreas Sebayang: Bluetooth 5.1 Direction Finding - Bluetooth gets a direction search . Golem. 29 January 2019.
  4. ↑ Iddo Genuth: Nokia's Wibree and the Wireless Zoo . ( Memento of April 3, 2014 in the Internet Archive ) In: thefutureofthings.com , (English). November 16, 2006, accessed December 30, 2015.
  5. ↑ M. Honkanen, A. Lappetelainen, K. Kivekas, Low end extension for Bluetooth , Radio and Wireless Conference, 2004 IEEE, 19-22. September 2004
  6. ↑ This website is dedicated to the European project MIMOSA. (No longer available online.) Archived from the original on August 4, 2016 ; accessed on December 15, 2015 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.mimosa-fp6.com
  7. ↑ Is Wibree going to rival Bluetooth? Retrieved December 15, 2015 .
  8. ↑ Wibree becomes ULP Bluetooth , Electronics Weekly, July 12, 2007.
  9. ↑ Bluetooth low energy ( memento of the original from March 3, 2009 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (English) @1@ 2Template: Webachiv / IABot / bluetooth.com
  10. ↑ Bluetooth low energy ( Memento of the original from September 4, 2009 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (English) @1@ 2Template: Webachiv / IABot / www.bluetooth.com
  11. ↑ Bluetooth 4.2 is getting faster and safer. Golem, December 3, 2014, accessed May 13, 2020 .
  12. ↑ Bluetooth Core Specification 5.0. Bluetooth SIG, December 6, 2016, accessed December 5, 2018 .
  13. ↑ Nico Juran: Bluetooth has a completely new audio architecture . Heise c't. January 21, 2020.
  14. ↑ Why Bluetooth is not the same as Bluetooth , golem.de, accessed on January 17, 2014
  15. ↑ [ https://3pl46c46ctx02p7rzdsvsg21-wpengine.netdna-ssl.com/wp-content/uploads/2019/03/Bluetooth_5-FINAL.pdf Bluetooth 5 Go Faster. Go Further.] . Bluetooth SIG. March 2019 .: "LE 1M is the PHY used in Bluetooth 4. It uses Gaussian Frequency Shift Keying and has a symbol rate of 1 mega symbol per second (Ms / s). It continues to be available for use in Bluetooth 5 and it's support is mandatory "
  16. ↑ Uwe Schulze: Briefly explained: Bluetooth 5 - tooth added . Heise iX. August 2017 .: "All new features of Bluetooth 5 only apply to low-energy devices - music and telephony do not benefit from them. The SIG intends to present an updated audio specification in 2018. Then it should also be possible to transmit audio via BLE. "
  17. ↑ Allen Henley: Bluetooth 5: More speeds, more range, new RF tests. EDN Network, November 21, 2017, accessed May 13, 2020 .
  18. ↑ Mark Hughes: What is Bluetooth 5? Learn about the Bit Paths Behind the New BLE Standard. Retrieved May 13, 2020 .
  19. ↑ bluetooth.com
  20. ↑ Dorine Gurney: Bluetooth 5 variations complicate PHY testing. EDN Network, January 29, 2018, accessed May 13, 2020 .
  21. ^ A b c Mike Ryan, iSEC Partners : Bluetooth: With Low Energy Comes Low Security. usenix, August 12, 2013, accessed May 13, 2020 .
  22. ↑ Philipp H. Kindt, Marco Saur, Michael Balszun, Samarjit Chakraborty: Neighbor Discovery Latency in BLE-Like Protocols . In: IEEE Transactions on Mobile Computing . tape 17 , no. 3 , March 1, 2018, ISSN  1536-1233 , p. 617–631 , doi : 10.1109 / tmc.2017.2737008 ( ieee.org [accessed June 29, 2018]).
  23. ↑ René Vogt: BLE Demo (CSI / Cnlab autumn conference). (No longer available online.) September 9, 2015, archived from the original on December 28, 2016 ; accessed on December 28, 2016 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.cnlab.ch
  24. ^ GATT Specification Documents. Retrieved December 15, 2015 .
  25. ↑ Android 4.3 detailed in new leak, but updates are minimal on The Verge , accessed July 19, 2013.
  26. ↑ iOS 5.0 , Apple , accessed September 28, 2013
  27. ^ Nokia website
  28. ↑ msdn.microsoft.com
  29. ↑ Gustavo Padovan: The big changes of BlueZ 5. (No longer available online.) February 22, 2013, archived from the original on September 23, 2017 ; Retrieved on July 12, 2016 : "As the MGMT interface is the only one to support the new Bluetooth Low Energy devices, BlueZ developers decided to drop support for the old interface once MGMT was completed. As a result, you need to be running Linux Kernel 3.4 or newer to use BlueZ 5. “ Info: The archive link was inserted automatically and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / padovan.org
  30. ↑ press.blackberry.com
  31. ↑ Archived copy ( memento of the original from September 30, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / rowebots.com
  32. ↑ Rafael Thiel: Why the Galaxy S8 has Bluetooth 5.0 but cannot use it . GIGA. May 30, 2017.
  33. ↑ Alexander Fagot: Samsung Galaxy S8: The truth about Bluetooth 5 in the new S-Class . Notebookcheck. May 28, 2017.
  34. ↑ Andreas Donath: Bluetooth 5.0 in the new MacBook Pro - what's the point? . MacLife. 15th July 2018.
  35. ↑ Get ready for Bluetooth mesh! | Bluetooth Technology website. In: blog.bluetooth.com. Retrieved July 6, 2017 .
  36. ↑ Low Energy: Mesh | Bluetooth Technology website. In: www.bluetooth.com. Retrieved July 18, 2017 .
  37. ↑ Markus Böhm: Why do Android users have to activate location access? . The mirror. June 16, 2020.
  38. ↑ Location access on Android phones . Stiftung Warentest. 17th June 2020.
  39. ↑ iBeacons: Wireless near-field communication with potential to become the standard ( Memento of the original from September 28, 2013 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. - Article at Beyond-print.de from September 25, 2013, accessed on September 28, 2013 @1@ 2Template: Webachiv / IABot / www.beyond-print.de