Wireless LANs are an evolving technology that many companies find worth watching. Although such networks aren't totally wireless, they do primarily use radio or infrared technology to connect subnets to the main body of a network. Although wireless networks are extensions of cabled networks, they cannot replace them. Technically, a few laptops joined together could constitute a wireless network, but, for our purposes, we will consider wireless networks that are connected to wired networks.
Without a doubt, wireless networks have more constrictions, usually related to the data transmission rates. However the convenience of turning on your PC and having an instant connection anywhere in a building sometimes outweighs the hassle of installing cables.
Most wireless LANs have an access point or wireless router that is connected to a wired network via a coax cable, Universal Serial Bus (USB), or Ethernet connection. Because most wireless LANs are extensions of a wired LAN, the access point is usually placed up high or in a similar location without many objects around it to obstruct the signal. The devices you want to connect to the wireless LAN must have a peripheral component to communicate with the access point. For laptops, this component is usually just a card to fit in the PCMCIA slot; for PCs, the card fits like a standard NIC or an attached USB dongle and antenna.
802.11a and 802.11b
The IEEE 802.11 committee established a standard in 1997 with a data rate of only 2Mbps. The standards supporting wireless are known as IEEE 802.11a, 802.11b, and 802.11g. Both 802.11a and 802.11b have distance limitations of 100 feet from the wireless access point or wireless router. 802.11b uses the 2.4GHz band, and currently supports data rates up to 11 Mbps.
Cisco wireless products, such as the Aironet series, integrate seamlessly into an existing network as a wireless overlay, or create freestanding all-wireless networks, enabling mobility quickly and cost effectively. These products are compliant with IEEE 802.11a and 802.11b standards using both single and dual band configurations.
A new wireless technology allowing speeds of up to 54Mbps is now available, and most companies provide legacy support of the older 802.11a and 802.11b technologies. This wireless technology is known as IEEE 802.11g, Wireless-G, or 54g, and continues to use the 2.4 GHz band.