Data is transmitted on local area networks in packets. Higher data rates transmit the packets more quickly, but
as data rates increase the communication overhead consumes a greater percentage of the packet size.
| Protocol |
Data rate |
Data percentage |
Overhead percentage |
Maximum throughput |
| 802.11 |
2Mbps |
80% |
20% |
1.6Mbps |
| 802.11g |
54Mbps |
46% |
54% |
24.7Mbps |
| 802.11g + Xpress |
54Mbps |
55% |
45% |
29.7Mbps |
| 802.11 + HighSpeed |
54Mbps |
63% |
37% |
34.1Mbps |
As shown in the table above, the original 802.11 protocol has a data rate of 2 Mbps and accommodates 80% data
and 20% overhead, for a maximum throughput of 1.6 Mbps. Compare that with the 802.11g standard, which has a data
rate of 54 Mbps, but only accommodates 46% data and 54% overhead, for a maximum throughput of 24.7 Mbps.
Broadcom Xpress™ technology, utilizing a technique called frame bursting, repackages the data to allow more
to be sent in a single packet, reducing the percentage used for overhead. This increases the maximum throughput
from 24.7 Mbps to 29.7 Mbps. (Frame bursting uses protocol from the 802.11 standard, so all 802.11 compliant
network devices can receive frame bursts, which increases overall network efficiency.)
High Speed Mode further reduces packet overhead by utilizing a unique timing algorithm. 125 High Speed Mode can
achieve a throughput of up to 34.1 Mbps—over 33% faster than the maximum 802.11g throughput of 24.7
Mbps1.
For best results |
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The maximum performance increase is experienced when all devices comprising the network support High Speed
Mode/SpeedBooster™. This includes the wireless router and all PCs connected to the network. In this
situation, all devices are capable of transmitting and receiving packets in High Speed Mode.
If a PC that does not support High Speed Mode is connected to the network, the High Speed Mode router will
step-down to Xpress Technology. Then any 802.11b/g client device on the network will receive information at
Xpress technology speeds, but only Xpress-enabled clients will transmit with higher than standard throughput.
Standard 802.11b/g clients will transmit at standard 802.11b/g rates.
Notes:
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Other factors, such as distance between the network's wireless devices, the makeup of the physical
environment such as walls, furniture, etc., and the presence of RF interference, affect wireless
network performance. Depending upon these factors, you may not experience the maximum theoretical
throughput for your specific implementation.
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In a home network connected to the internet using a residential gateway (i.e. a broadband connection),
the speed of the connection to the internet will not be improved by the High Speed Mode performance
enhancements within your local area network. While throughput within the network may reach speeds up to
34.1 Mbps, internet connection speed will be limited by the residential gateway, which is typically 500
Kbps to 2 Mbps.
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1 Source: Broadcom corporation.
* When operating in 125 High Speed Mode, this Wi-Fi® device achieves an actual
throughput of up to 34.1 Mbps, which is the equivalent throughput of a system following 802.11g protocol and
operating at a signaling rate of 125 Mbps. Actual throughput will vary depending on environmental, operational
and other parameters.
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