Receiver SensitivityRangeData Rate (See
Note 2)
Maximum Tx Power
(See Note 1)
Standard
-96 dBm1,010 ft (308 m)1 Mbps17 dBm
-85 dBm951 ft (290 m)2 Mbps
-90 dBm919 ft (280 m)5.5 Mbps
-87 dBm902 ft (275 m)11 Mbps
Note
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 Communications Manager Administration phone configuration, then the Traffic Stream Rate
Set IE (CCX V4) is used.
For more information about supported data rates, Tx power and Rx sensitivity for WLANs, see the Cisco
Unified IP Phone 9971 Wireless LAN Deployment Guide at this location:
http://www.cisco.com/en/US/products/ps10453/products_implementation_design_guides_list.html
Wireless Modulation Technologies
Wireless communications use the following modulation technologies for signaling:
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 other
data packets 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. When used
with 802.11g and 802.11a, OFDM can support data rates as high as 54 Mbps.
The following table provides a comparison of data rates, number of channels, and modulation technologies
by standard.
Table 10: Data Rates, Number of Channels, and Modulation Technologies by IEEE Standard
802.11a802.11g802.11bItem
6, 9, 12, 18, 24, 36, 48,
54 Mbps
6, 9, 12, 18, 24, 36, 48,
54 Mbps
1, 2, 5.5, 11 MbpsData rates
Cisco Unified IP Phone 8961, 9951, and 9971 Administration Guide for Cisco Unified Communications Manager
10.0
54
802.11 Standards for WLAN Communications
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