Wireless Physical Transport

The Institute of Electrical and Electronics Engineers (IEEE) has developed a set of wireless standards that are commonly used for local wireless communications for PCs and laptops called 802.11. Currently, 802.11b and 802.11a are two basic standards that are accepted on a wider scale today. These standards are transmitted by using electromagnetic waves. Wireless signals as a whole can either be radio frequency (RF) or infrared frequency (IR), both being part ofthe electromagnetic spectrum (Boncella, 2002). Infrared (IR) broadcasting is used for close range communication and is specified in IEEE 802.11. The IR 802.11 implementation is based on diffuse IR which reflects signals off surfaces such as a ceiling and can only be used indoors. This type of transport is seldom used.

The most common physical transport is RF. The 802.11 standard uses this transport. Of the RF spectrum, the 802.11 standard uses the Industrial, Scientific, and Medical (ISM) RF band. The ISM band is designated through the following breakdown:

802.11b is the most accepted standard in wireless LANs (WLANs). This specification operates in the 2.4 gigahertz (GHz) S-band and is also known as wireless fidelity (WiFi). The speeds at which 802.11b can have data transfer rates is a maximum of 11 megabits per second (Boncella, 2002).

The 802.11a standard, commonly called WiFi5, is also used and operates with minor differences from the 802.11b standard. It operates in the M-band at 5.72GHz. The amount of data transfer has been greatly increased in this standard. The max link rate is 54 Mbps (Boncella, 2002).

There are other variations of 802.11 that may be used on a wider basis very soon. These are 802.11g and 802.11i. 802.11g operates in the same 2.4GHz S-band as 802.11b. Because they operate in the same band, 802.11g is compatible with 802.11b. The difference is that 802.11g is capable of a max link rate of 54 Mbps. The 802.11i standard is supposed to improve on the security of the Wired Equivalent Privacy (WEP) encryption protocol (Boncella, 2002).

The future ofthe 802.11 standard will bring other specifications—802.11c "helps improve interoperability between devices," 802.11d "improves roaming," 802.11e "is touted for its quality of service," 802.11 f "regulates inter-access-point handoffs," and 802.11h "improves the 5GHz spectrum" (Worthen, 2003).

Another option for close range communication between devices is Bluetooth technology or through infrared port usage. Bluetooth is a short-range wireless standard that allows various devices to communicate with one another in close proximity, up to 10 meters (Tarasewich et al., 2002). The Infrared Data Association (IrDA) developed a personal area network standard based on infrared links, in 1994, which brought technology that is extremely useful in transferring applications and data from handheld devices such as PDAs (Agrawal et al., 2003) and between computers and other peripheral devices. It requires line ofsight and covers a shorter distance than Bluetooth.

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