125 High Speed Mode

125 High Speed Mode (125HSM) is Broadcom's proprietary frame-bursting and compression technology to improve 802.11g wireless LAN performance. The throughput transmission speed limit when using 125HSM is claimed to be up to 35%-40% higher than standard 802.11g.

The "125" in "125 High Speed Mode" refers to performance at a theoretical signaling rate of 125 Mbit/s: a 125HSM device can achieve a maximum throughput of 34.1 Mbit/s, which is the equivalent throughput of a system strictly following all 802.11g and operating at a signaling rate of 125 Mbit/s.

When 125HSM was originally announced in 2004, it was called Afterburner. It is currently marketed as a proprietary extension of Broadcom's Xpress technology, their standards-based frame-bursting approach that is supported by their 54g Wi-Fi chipsets.

Other vendors have marketed 125HSM products under a variety of names:

Manufacturers that have licensed 125HSM technology from Broadcom include Belkin, Buffalo Technology, Dell, Gateway, Hewlett-Packard, Asus, Linksys (now part of Belkin), Motorola, U.S. Robotics and Netcomm. In general, 125HSM products from different vendors are all interoperable in 125HSM mode.

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