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AP-51xx Access Point Product Reference Guide
The access point uses electromagnetic waves to transmit and receive electric signals without wires.
Users communicate with the network by establishing radio links between mobile units (MUs) and
access points.
The access point uses DSSS (direct sequence spread spectrum) to transmit digital data from one
device to another. A radio signal begins with a carrier signal that provides the base or center
frequency. The digital data signal is encoded onto the carriers using a DSSS chipping algorithm. The
access point radio signal propagates into the air as electromagnetic waves. A receiving antenna (on
the MU) in the path of the waves absorbs the waves as electrical signals. The receiving MU interprets
(demodulates) the signal by reapplying the direct sequence chipping code. This demodulation results
in the original digital data.
The access point uses its environment (the air and certain objects) as the transmission medium.The
access point
can either transmit in the 2.4 to 2.5-GHz frequency range (802.11b/g radio) or the 5.2
GHz frequency range (802.11a radio), the actual range is country-dependent. Symbol devices, like
other Ethernet devices, have unique, hardware encoded Media Access Control (MAC) or IEEE
addresses. MAC addresses determine the device sending or receiving data. A MAC address is a 48-
bit number written as six hexadecimal bytes separated by colons. For example: 00:A0:F8:24:9A:C8
Also see the following sections:
•
Cellular Coverage
•
MAC Layer Bridging
•
Content Filtering
•
DHCP Support
•
Media Types
•
Direct-Sequence Spread Spectrum
•
MU Association Process
•
Operating Modes
•
Management Access Options
1.3.1 Cellular Coverage
An access point establishes an average communication range with MUs called a Basic Service Set
(BSS) or cell. When in a particular cell, the MU associates and communicates with the access point
supporting the radio coverage area of that cell. Adding access point's to a single LAN establishes
more cells to extend the range of the network. Configuring the same ESSID (Extended Service Set
Identifier) on all access points makes them part of the same Wireless LAN.
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