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Bluetooth, Wireless Local Area Networks (WLAN), and Ultrawideband (UWB)

Bluetooth, wireless local area networks and ultra-wideband are applications of high-frequency electromagnetic radiation that are used for the wireless and mobile connection of various pieces of telecommunications and data-processing equipment.

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Bluetooth

Bluetooth is a short-range wireless technology that is primarily intended for coupling peripheral devices in the office environment (such as PCs, notebooks, laptops and palmtops, organizers, printers and scanners). Many smartphones also contain a Bluetooth transmitter.

The frequency range used is between 2400 and 2483 MHz.

Bluetooth has three classes of transmitting power:

  • Class 1: maximum transmitting power of 100 mW

    for applications with ranges of up to approx. 100 metres

  • Class 2: maximum transmitting power of 2.5 mW

    for typical office workspace ranges of up to some 10 metres

  • Class 3: maximum transmitting power of 1 mW

    for applications in the immediate short range, with ranges of up to approx. 10 metres.

Many of the devices on the market are assigned to classes 2 and 3.

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WLAN

WLAN is used to set up local computer networks. The devices can be connected to one another wirelessly using factory-installed wireless interfaces in laptop and tablet computers or via corresponding expansion cards. Central access points (or hotspots) allow devices to connect to higher-level network structures – such as, in the professional context, a company data network. Many smartphones also contain a WLAN interface, allowing wireless Internet connections to be established in public places such as hotels or airports, for example, as well as in private settings, without using a mobile communications network.

Like Bluetooth, WLAN also uses the 2.4 GHz frequency band. Frequencies between 5 and 6 GHz can also be used.

The maximum permissible radiated power of the devices depends on the frequency range used:

  • Frequencies around 2400 MHz: 100 mW EIRP
  • Frequencies ranging from 5150 to 5350 MHz: 200 mW EIRP if used exclusively within closed spaces
  • Frequencies ranging from 5470 to 5725 MHz: 1 W EIRP
  • Frequencies ranging from 5925 to 6425 MHz: 200 mW EIRP

Frequencies above 5250 MHz may only be used with automatic power regulation. Otherwise, 50 % lower maximum values apply.

Recommended limit values are observed

Analyses as part of the German Mobile Telecommunication Research Programme showed that emissions from WLAN and Bluetooth devices in typical domestic or office environments are significantly lower than the recommended limit values (see Determination of exposure caused by wireless technologies used in homes and offices).

Situations such as working with a laptop on one’s lap, in which the WLAN transmitter may be located directly above the thigh, depending on the device's design, can lead to local exposure levels similar to those when making a call on a mobile phone. Where manufacturers indicate minimum distances for operation close to the body, these distances should be adhered to.

Further information on the subject of Bluetooth and WLAN can be found in the information sheet Sprach- und Datenübertragung per Funk: Bluetooth und WLAN ("Wireless speech and data transmission: Bluetooth and WLAN" in German only).

UWB

UWB is a technology for high-speed data transmission that – as the name suggests – uses a particularly wide frequency band. Its potential areas of application are above all in high-speed data services that operate over short distances.

The main area of application is expected to be in

  • audio
  • video and
  • data transmission

between devices that are not at a particularly large distance from one another (several metres). Examples include data transmission between

  • computers
  • printers
  • external hard disks and
  • MP3 players or
  • between components of home cinema systems.

Given the achievable transmission rates of several hundred Mbit/s (and sometimes into the Gbit/s range), UWB has the potential to replace the cable connections that have been prevalent for these applications until now.

Moreover, there are a number of other conceivable applications:

  • in the transport engineering sector: radar applications, e.g. for collision avoidance
  • in passenger screening: e.g. for the detection of dangerous items
  • in medical technology: e.g. for the detection of tumours
  • in radio-frequency identification (RFID): for the automatic identification and positioning of objects and living creatures using electromagnetic fields.

Frequency range and transmitting power

UWB uses frequency ranges that are partly designated for other (narrow-band) radio services. There is therefore a need to regulate radio technology in order to avoid interference. For the European Community, a European Commission Decision (2007/131/EC) was reached in February 2007 describing the use of the radio spectrum for UWB equipment. A number of aspects of this Decision were amended in 2014 (2014/702/EU). In Germany, the stipulations set out by the Federal Network Agency are binding.

Recommended limit values are not exceeded

A research project was carried out as part of the German Mobile Telecommunication Research Programme in order to obtain reliable data for the maximum possible and average expected exposure levels caused by various ultra-wideband radio applications as early as possible. This research showed that equipment operating based on UWB technology results in very low levels of exposure, although the frequency range covered is very large (with a bandwidth of up to 7.5 GHz).

Levels in excess of the recommended limit values for the specific absorption rate (SAR) are not possible if the restrictions on transmitting power stipulated by the German Radio Installation Act are complied with.

State of 2023.11.15

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