Understanding Wlan Standards And Technologies; 802.11 Standards For Wlan Communications - Cisco 7925G - Unified Wireless IP Phone VoIP Administration Manual

Chapter 2 Overview of the VoIP Wireless Network
•
•
•
•
For more information about Cisco Unified Wireless Networks, refer to
http://www.cisco.com/en/US/products/hw/wireless/index.html

Understanding WLAN Standards and Technologies

This section describes the following concepts:
•
•
•
•
•
•

802.11 Standards for WLAN Communications

Wireless LANs must follow the Institute of Electrical and Electronics Engineers (IEEE) 802.11
standards that define the protocols that govern all Ethernet-based wireless traffic. The Cisco Unified
Wireless IP Phone 7925G supports the following standards:
•
•
•
•
Cisco Unified Wireless IP Phone 7925G Administration Guide for Cisco Unified Communications Manager 7.0(1)
OL-15984-01
Cisco Catalyst 3750 Series Integrated Wireless LAN Controllers—Adds wireless LAN controller
functions to the stackable Cisco Catalyst 3750G Series Switches to improve operating efficiency,
security, mobility, and ease of use for WLAN administrators.
Wireless Control System (WCS)—Provides a powerful systems management. System
administrators can design, control, and monitor enterprise WLANs from a centralized location.
Cisco 2700 Series Wireless Location Appliance—802.11 based location tracking solution for asset
tracking, IT management, and location based security. An open API is included.
Cisco Wireless LAN Client Adapters—Available in CardBus, PCMCIA and PCI form factors, Cisco
Aironet Wireless LAN Client Adapters connect desktop and mobile computing devices to the
WLAN in 802.11b-compliant or 802.11a-compliant network.
802.11 Standards for WLAN Communications, page 2-3
Radio Frequency Ranges, page 2-4
802.11 Data Rates, Tx Power, Ranges, and Decibel Tolerances, page 2-4
Wireless Modulation Technologies, page 2-5
AP, Channel, and Domain Relationships, page 2-6
WLANs and Roaming, page 2-7
802.11b—Specifies the radio frequency (RF) of 2.4 GHz for both transmitting and receiving data.
Commonly called the Wi-Fi standard.
802.11g—Uses the same unlicensed 2.4 GHz band as 802.11b, but extends the data rates to provide
greater performance by using Orthogonal Frequency Division Multiplexing (OFDM) technology.
OFDM is a physical–layer encoding technology for transmitting signals by using RF.
802.11a—Uses the 5 GHz band that provides more channels and improved data rates by using
OFDM technology. Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC)
supports this standard.
802.11d—Enables APs to communicate available radio channels and acceptable power levels. The
Cisco Unified Wireless IP Phone 7925G will always give precedence to 802.11d to determine which
channels and powers to use. If the information is unavailable, then the phone will fallback to the
locally configured regulatory domain.

Understanding WLAN Standards and Technologies

2-3