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Lecture 8, Wireless LANs

Infrared LANs

Transmission Techniques

Three technologies used for IR data transmission:

  1. Direct beam infrared
  2. Omnidirectional
  3. Diffused

Spread Spectrum LANs

Frequency Hopping

Direct Sequence

Narrowband Microwave LAN

Narrowband microwave refers to the use of a microwave radio frequency band for signal transmission

Licensed Narrowband RF

Unlicensed Narrowband RF

Wireless LAN Standards

802.11 Services

Services needed to provide functionality equivalent to wired LANs

In addition 802.11 includes the following:

Physical Medium

Three physical medium defined in 802.11

  1. Infrared defined at 1 and 2 Mbps operating at wavelength 850-950 mm
  2. Direct sequence spread spectrum operating in 2.4 GHz ISM band. Up to seven channels each with 1 or 2 Mbps data rate
  3. Frequency hopping spread spectrum operating in 2.4 GHz ISM

Medium Access Control