Cisco Cisco Aironet 1400 Wireless Bridge Guía De Diseño
Copyright © 2004 Cisco Systems, Inc. All rights reserved.
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Figure 1.
Typical Bridge application used to connect different buildings across a
campus or a metro area
Cisco Aironet Bridges support IEEE 802.1d Spanning Tree and can therefore participate in
complex Layer 2 network designs involving redundant or meshed links.
1.1 Channels and Data Rates
IEEE 802.11a defines requirements for a PHY operating in the 5.0 GHz Unlicensed National
Information Infrastructure (UNII) frequency band and data rates ranging from 6 Mbps to 54 Mbps
in seven increments-6, 9, 12, 18, 24, 36, 48 & 54 Mbps. It uses the Orthogonal Frequency
Division Multiplexing-, which is a multi carrier system as compared to single carrier systems.
OFDM allows sub channels to overlap, giving us a high spectral efficiency. The modulation
technique allowed in (OFDM) is more efficient than the spread spectrum techniques use. More bits
are stuffed per second per hertz and provides up to 54 Mbps of data rate to network users.
For US-based 802.11a standard, the 5GHz unlicensed band covers 300 MHz of spectrum and
supports 12 non-overlapping channels. The channel frequencies and numbering defined in IEEE
802.11a start at 5 GHz for United States and each channel is spaced 5 MHz apart. The Figure 2
below shows the center frequency of the channels. The frequency of the channel is 10MHz either
side of the dotted line.
Information Infrastructure (UNII) frequency band and data rates ranging from 6 Mbps to 54 Mbps
in seven increments-6, 9, 12, 18, 24, 36, 48 & 54 Mbps. It uses the Orthogonal Frequency
Division Multiplexing-, which is a multi carrier system as compared to single carrier systems.
OFDM allows sub channels to overlap, giving us a high spectral efficiency. The modulation
technique allowed in (OFDM) is more efficient than the spread spectrum techniques use. More bits
are stuffed per second per hertz and provides up to 54 Mbps of data rate to network users.
For US-based 802.11a standard, the 5GHz unlicensed band covers 300 MHz of spectrum and
supports 12 non-overlapping channels. The channel frequencies and numbering defined in IEEE
802.11a start at 5 GHz for United States and each channel is spaced 5 MHz apart. The Figure 2
below shows the center frequency of the channels. The frequency of the channel is 10MHz either
side of the dotted line.
Figure 2.
UNII 3 Band