Wireless Modulation Technologies - Cisco 8961 Administration Manual

Understanding WLAN Standards and Technologies
Table 6-2
Standard
802.11b
1. Adjusts dynamically when associating with an AP if the AP client setting is enabled.
2. Advertised rates by the APs are used. If the Restricted Data Rates functionality is enabled in the Cisco Unified
For more information about supported data rates, tx power and rx sensitivity for WLANs, see
Unified IP Phone 9971 Wireless LAN Deployment

Wireless Modulation Technologies

Wireless communications uses the following modulation technologies for signaling:
•
•
Table 6-3
standard.
Table 6-3
Item
Data Rates
Non-overlapping
Channels
Wireless
Modulation
Cisco Unified IP Phone 8961, 9951, and 9971 Administration Guide for Cisco Unified Communications Manager 8.6 (SIP)
6-6
Tx Power, Data Rates, Ranges, and Decibels by Standard (continued)
Maximum Tx
1
Power
17 dBm
Communications Manager Administration phone configuration, then the Traffic Stream Rate Set IE (CCX V4) is used.
Direct-Sequence Spread Spectrum (DSSS)—Prevents interference by spreading the signal over the
frequency range or bandwidth. DSSS technology multiplexes chunks of data over several
frequencies so that multiple devices can communicate without interference. Each device has a
special code that identifies the data packets for the device and all others are ignored. Cisco wireless
802.11b/g products use DSSS technology to support multiple devices on the WLAN.
Orthogonal Frequency Division Multiplexing (OFDM)—Transmits signals by using RF. OFDM is
a physical-layer encoding technology that breaks one high-speed data carrier into several
lower-speed carriers to transmit in parallel across the RF spectrum. OFDM, when used with 802.11g
and 802.11a, can support data rates as high as 54 Mbps.
provides a comparison of data rates, number of channels, and modulation technologies by
Data Rates, Number of Channels, and Modulation Technologies by IEEE Standard
802.11b
1, 2, 5.5, 11 Mbps
3 (Japan uses 4)
DSSS
Chapter 6
2
Data Rate Range
1 Mbps 1,010 ft (308 m)
2 Mbps 951 ft (290 m)
5.5 Mbps 919 ft (280 m)
11 Mbps 902 ft (275 m)
Guide.
802.11g
6, 9, 12, 18, 24, 36, 48,
54 Mbps
3
OFDM
Understanding the VoIP Wireless Network
Receiver Sensitivity
-96 dBm
-85 dBm
-90 dBm
-87 dBm
802.11a
6, 9, 12, 18, 24, 36, 48,
54 Mbps
Up to 23
OFDM
Cisco