Requirements to a wireless connection:

	Two or more locations with distances up to 50 km should be connected;
	Bandwidth of min. 2Mpbs required;
	Only digital signals should be transmitted.

Basically there are three different technologies, which are suitable for transmitting voice and/or data signals. Every of these three technologies has it's own advantages and disadvantages.

The following table gives an overview about these technologies.

	Wireless communication systems
	Medium			WLAN (IEEE 802.11)		Free Space Optics		Microwave links
	Transmission rate:			Some Mbps		4x2 .. 1.250 Mbps		4x2 .. 4 x 155 Mbps
	Maximum distance			Some km		< 2 km		< 50 km
	Security against tapping			High		Extremely high		Very high
	Availability			> 99 %		> 99 %		> 99,9 %
	Interference resistance against other users			Moderate, because of ISM frequencies		Interference not possible		Very high, because of exclusive frequence for each user
	Guaranteed QOS			No		Yes		Yes
	Interfaces			Ethernet 10/100BT		E1, Fast and Gigabit Ethernet, SDH/STM-1		E1, 10/100BT, STM-1
	Installation			Easy		Medium		Medium
	Precision of adjusting			Small		Very high		High
	Approval			License free		License free		Needs License from PTT

Because of different license terms in foreign countries, CBL has decided to sell only free space optics outside of germany.