Wi-Fi Issues

Wireless Standard  (Background on 802.11 Standard)

802.11b Wireless Products

802.11b Data Rate

Datarate automatic fallback to lower datarate, when RSSI (signal strength) goes lower. The original design in WaveLAN card use a different scheme: it falls back when several transmission attempts fail.
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Wireless tools

Wi-Fi Sniffer

Driver in Linux

Special Report: Linux Driver for Cisco Aironet Client Adaptor

Refer to Linux Wireless Howto
Hostap driver is a very popular driver. All Prism-2 based cards can use this driver.And....
HostAP enables 802.11b access point functionality utilizing the secondary (STA) firmware of Intersil's Prism2, Prism2.5, or Prism3 chipsets for time sensitive tasks. All other functionality is handled via the driver, including WEP and passing frames off to a port authenticator, like FreeRADIUS. Presently, HostAP works with Intersil's Prism chipset and cards utilizing PCI and PC Card interfaces to the host system. (PLX bridging is also supported.) I found currently 2 kind of pcmcia client cards can be turned into AP with hostap driver:

  1. Netgear MA401
  2. LinkSys (very old one with no version label)
  3. SMC 2623 v.1 (WINLAB only has v.2. it is not of Intersil-Prism)

HostAP dirver usually has three versions 0.0.3, 0.0.4, 0.1.2 etc. The first version support Tx-power settings while others not.

MADWIFI: Atheros Chip and It's driver:

This driver for 802.11a/b is very powerful to actually implementing all MAC schemes in the driver (software), not firmware in the chip. Atheros based cards do not have firmware, it is which necessitates the HAL, since that HAL (Hardware and OEM Abstraction Layers), in effect acts are the firmware. If you want to hack on madwifi code, hack on ath_pci and wlan, since, as Greg said in the middle of a rather large flame war, "the device will quite happily transmit any bit pattern you put in the tx buffer...".

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MAC Scheduler in the system:

My presentation about UpperMAC.

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