Figure 1-4. Radio Frequency Bands - Nortel BayStack 660 Use Manual

The physical layer is a 2.4 GHz spread spectrum, direct sequence radio that
replaces the Ethernet cable normally required between LAN workstations.
Figure 1-4
Telecommunications
Television
FM Broadcast
(88 to 108 MHz)
Short Wave Radio
AM Broadcast
(560-1605 KHz)
Audio Frequencies
Figure 1-4.
A low-power radio operates within the 2.4000 to 2.4835 GHz band of the
unlicensed Industrial, Scientific, and Medical bands (ISM). It is divided into 78,
one MHz channels. The direct sequence scheme causes the radio to broadcast on
eleven channels simultaneously, each separated by a single channel. Interference
on any one channel can be tolerated as all eleven channels utilized carry the exact
same data.
Using Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA), each
string of data is sent with an additional signaling information designed to maintain
transmission efficiency. Every packet includes three signaling packets:
• Request to send (RTS)
RTS reserves the area around the sender.
• Clear to send (CTS)
203939-B
illustrates the frequency spectrum for this radio technology.
Super
High
Ultra
High
Very
High
High
Medium
Low
Very
Low
Radio Frequency Bands
5.850 GHz
Broadband
5.725 GHz
2.4835 GHz
802.11
2.400 GHz
928 MHz
Cellular
902 MHz
8698EB
Introduction
1-7