Channelized Services Overview; Open System Interconnection Reference Model - Nortel BayStack 650 User Manual

Using the BayStack 650 Wireless LAN Access Point
• Wall mountable or free standing unit with Ethernet connectors.
• A PC card slot for a BayStack 650 PC Card.
• Bridging, management, and security software for access point operations.
Wireless technology offers users freedom of movement and provides
administrators greater flexibility in LAN configurations. The BayStack 650
Access Point uses Frequency hopping spread spectrum (FHSS or FH) radio
frequency (RF) signals. This enables a laptop computer with a PC card that is
operating in FH modulation (for example, BayStack 650), to connect to a
BayStack 600 Series Wireless LAN.
Note: The BayStack 650 Access Point and the BayStack 650 PC Card (also
known as the BayStack 650 Wireless LAN products) both operate using a
FH modulation technique. Products with different modulation (such as the
BayStack 660 Access Point) cannot be used together.

Channelized Services Overview

With frequency hopping, a radio transmits and receives on one frequency for a
short period of time and then randomly moves to another frequency every tenth of
a second. Frequency hopping technology reduces susceptibility to interference
from other radio transmitters and noise sources in the same 2.4 GHz range since
the transmission is constantly shifting from one frequency to the next. The result
is a performance gain, better security, and scalability in the use of the product.
Load balance your network traffic by distributing the communication traffic
evenly over several access points.

Open System Interconnection Reference Model

The BayStack 650 Wireless LAN products conform to the Open System
Interconnection (OSI) reference model for data communications. The lower
two layers of the seven layer model are implemented as illustrated in
The MAC portion of the Data Link layer interfaces to the higher level software
through the network drivers. The IEEE 802.11 protocol has a four-part packet
handshake to assure fair and controlled access to the media. It provides virtual
collision detection and enhanced error detection and retransmission.
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Figure 1-1.
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