Wireless Data transmitting

	WLAN
	DECT
	IrDA
	Bluetooth®

For the wireless data transmitting over short distances there is a large series of technologies. Different solutions line up in order to free the user from the cable muss: e.g. infrared (IrDA), IEEE 802.11 (WLAN), HomeRF, Hyper LAN, DECT and Bluetooth®. On this page we will give you a short overview of the main technologies and give reasons for the special meaning of Bluetooth® for the wireless data transmitting.

In Europe chiefly WLAN, DECT, IrDA and Bluetooth® matter. HomeRF which is in a way a combination of DECT for speech and WLAN for data is widely spread in the USA (also as an equivalent to the European DECT standard for wireless telephony), but in Europe it is neither really used in the telephony nor in the network area. Also the European standard HyperLAN/2 which comes from the field of mobile radio and which has in fact advantages in comparison to WLAN did not win recognition (yet).

WLAN (Wireless LAN – wireless local network) is mainly used for the wireless networking of PCs over short and average distances. The so-called access point supplies data to the devices in the network. Theoretically 1.5 km can be bridged, in practice the achievable ranges are about 30 m in buildings and 300 m outside. The achievable data rates are depending on the actual WLAN characteristics (IEEE 802.11 a to i), WLAN 802.11b is today mainly used with data rates of up to 11 Mbit/s; but for multimedia applications mostly 802.11g with up to 54 Mbit/s. WLAN is little common outside the network area – not only due to its high energy consumption and the high interference liability. Other than DECT or Bluetooth® ,WLAN is not real time and therefore it is less appropriate for speech communication.

Contrary to WLAN, DECT (digital enhanced cordless telecommunications) with its limited data rates (24 to 552 kBit/s) is not designed for the network area but as its name already indicates it is mainly used for wireless telecommunication. The range of DECT in buildings is by default less than 50 m outside about 300 m. Indeed among experts DECT is under discussion as a possible alternative for Bluetooth® replacing the use of wires – but as the latter, the DECT features real time, little interference liability and little energy consumption. High manufacturing cost, moderate bandwidth and above all, the little flexibility in the application areas argue for an area-wide usage for the data communication. This way it may be assumed that the prior application field of DECT will further on mainly be limited to the wireless speech communication.

Also IrDA – the data transmitting via infrared according to the standard of the “Infrared Data Association” – will in the long run be less important in the data communication. Indeed IrDA is still today the most wide-spread system for wireless communication between consumer devices (most notebooks and mobile phones dispose of an IrDA interface) but there are even more serious disadvantages towards the competition, mainly towards Bluetooth® : The range and the data rate are too little. At good light conditions the infrared signal bridges about 1 m – in most cases less. Data are transmitted with max 115.2 kbit/s. According to the latest, little known FIR-Standard (Fast IR) it shall be possible to send with 4 Mbit/s – but also here a direct intervisibility is required, the sensitivity to interferences is high and it is not possible to protect the system against wiretapping (encryption) therefore, it is most susceptible that IrDA will soon be superseded by Bluetooth®. This is not least shown in the increasing number of Bluetooth® mobile phones – as it was due to mobile phones that the IrDA is nowadays widespread.

Bluetooth® is working as the WLAN in the license-free ISM-network and achieves data rates of up to 2.2 Mbit/s at ranges of up to 100 m (see “What are the capabilities of Bluetooth®”). Contrary to DECT, Bluetooth® is not only appropriate for the speech communication, but also for data transmitting. But the technology does not directly compete with the network standard WLAN. As it had primarily been designed as a pure replacement for cables, it mainly shows its advantages as uncomplicated and rapid “end-to-end”-interface for the data interchange between different devices. With Bluetooth® you can connect peripheral devices, mobile phones, PDAs or digital cameras with the PC, replace serial cable connections or operate machines by remote control.

The little energy consumption distinguishes Bluetooth® towards other remote control technologies, above all compared to WLAN. In the standby operation, the consumption is generally considerably less than 0.3 mA, for data transmitting from 0.3 to 30 mA. Furthermore, Bluetooth® chips can be produced space saving and at an affordable price. Not least, Bluetooth® is very simple in its application: The connection is established automatically, generally there is no need to configure the device.

Bluetooth® can be integrated to new or existing products in a very simple way. Bluetooth® adapters serve to retrofit PCs, notebooks or other devices with an adequate interface (USB or RS-232). This way you can for example establish wireless connections between devices and serial interfaces, e.g. measuring instruments, modems, printers or PCs and any other devices which are adequate for Bluetooth® without a problem with the help of LinTech Bluetooth® RS-232 adapters. Complex cabling to read out data or to operate machines or systems by remote control is eliminated, the installation work is little. There is no need to install neither drivers nor software to the concerned devices – the complete Bluetooth® software is already integrated to the adapter. For industrial applications, LinTech offers its Bluetooth® OEM moduls by which the manufacturers can equip their products with the Bluetooth® functionality at an affordable price.

back to top