"Wireless technologies like WLAN (Wireless Local Area Network), Bluetooth, GPRS (General Packet Radio Service), GSM (Global System for Mobile communications), and IrDa (Infrared Data) serve different niches. While WLAN supports higher speeds and longer range than Bluetooth, it also has higher costs and higher power consumption. GPRS is slower than Bluetooth and WLAN, but can be used on the move. Despite their diversity, or rather because of it, devices with multiple wireless capabilities can use them in tandem. For example, a device can switch transparently from GPRS on the road to a cheaper WLAN in an Internet cafe for network connectivity, depending on location input from a GPS module. A cell phone can communicate through Bluetooth to a heart rate monitor and send an alert over GSM to a doctor if the patient's heart rate crosses a certain threshold.
"These wireless technologies are widely available today in the form of PCMCIA or Compact Flash (CF) cards, or as USB devices. Most computer systems, including embedded devices, have PCMCIA, CF, or USB interfaces, thus instantly enabling them to take advantage of wireless technologies even if they do not have built-in support for them. This article examines examples of such wireless devices and explores the respective Linux implementations of the device drivers, bus technologies, and protocols.
"You'll first see how WLAN devices work on Linux by tracing the code flow for an example WLAN card. Then you'll see how several Bluetooth devices interface with the Linux Bluetooth stack and other kernel layers. Next, you'll learn how to get GPRS and GSM devices to work with Linux. The article ends with the examination of Linux IrDa support and a brief look at performance issues faced by wireless networking devices..."
