Ieee 802.11 Protocol - Psion Teklogix 9150 User Manual

Chapter 1: Introduction

IEEE 802.11 Protocol

1.5.3 IEEE 802.11 Protocol

The IEEE 802.11 protocol is an OSI standard for Wireless Local Area Networks
(WLANs). With this standard, any IEEE 802.11 radio can communicate with any
other similarly-equipped device. However, IEEE 802.11 does not provide a standard
for a total WLAN system. IEEE 802.11 solely standardizes two communications
layers: Physical (PHY) and Medium Access Control (MAC). Three different PHY
layer media are covered: 2.4 GHz Direct Sequence Spread Spectrum radio,
2.4 GHz Frequency Hopping Spread Spectrum radio, and infrared. Each station
in a WLAN system has its own unique MAC address.
Important:
IEEE 802.11 uses 2.4 GHz radios of relatively low power. The range is limited
to no more than a hundred feet or so, depending on the conditions, and is usually
restricted to "line of sight" operation. Therefore, most wireless networks need more
than one coverage area, with terminals moving between the areas. To integrate
those areas, systems using IEEE 802.11 protocol for their wireless networks
require an IEEE 802.11-equipped bridge device (or access point), such as the
9150 Wireless Gateway.
Using bridging software, the 9150 Wireless Gateway enables communication
between any wireless IEEE 802.11-equipped stations and LAN stations operating
on Ethernet or Token Ring. The 9150 itself is resident on the LAN and functions as
a MAC bridge, providing transparent integration between the stations on the wire-
less and wired networks.
Each terminal is associated with one 9150. A frame from an RF terminal is sent to
the 9150 that the terminal is associated with. The terminal puts a destination MAC
address in the frame, which specifies a hardware address on the wired LAN side.
Because the receiving 9150 is connected to an Ethernet or Token Ring network, it
encapsulates the data in an Ethernet or Token Ring frame, respectively, including the
destination MAC address specified by the terminal. The 9150 then sends the frame
onto the physical network; the frame is picked up by whichever device is at the des-
tination hardware address.
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Teklogix 9150 Wireless Gateway User Manual
Equipment using one physical medium (e.g. Frequency Hopping
versus Direct Sequence) will not interoperate with equipment using
a different physical medium.