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1.3 Theory of Operations
To understand access point management and performance alternatives, users need familiarity with
access point
functionality and configuration options. The access point includes features for different
interface connections and network management.
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
•
AP-51xx MAC Address Assignment
1-19
Introduction
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