Lecture 5: Wireless Measurements

Wireless Networks
Lecture 5: Wireless Measurements

The Frequency Spectrum and Wireless LANs:
The frequency spectrum ranges from very low frequencies at 1 Hz to gamma rays at 10^23 Hz. Within that very large range of frequencies, there are three frequency bands used for wireless LANs. Those three bands are collectively referred to as Industrial, Scientific, and Medical (ISM) bands.
These three bands represent unlicensed frequency bands on a worldwide basis.

ISM Bands:
Although ISM bands are unlicensed, they are not unregulated and a distinction between the two is important. The fact that an ISM band is unlicensed means that organizations can transmit using ISM equipment without having to obtain a license to use such equipment.
However, both the power and transmission characteristics of equipment, such as the frequencies are regulated for operation in an ISM band. In the United States, the FCC (Federal Communication Commission) is responsible for such regulation.
Two additional ISM frequency bands are referred to as the 2.4-GHz and the 5.0- GHz bands.
The 2.4-GHz ISM band ranges from 2.4000 to 2.4835 GHz, resulting in 83.5 MHz of available bandwidth.
The IEEE 802.11b standards operate in the 2.4-GHz frequency band.

Measurements:
Measurements can be used to qualify the level of received power as well as power gains and losses.