What is WiFi Systems

In addition to 3G, WiFi based systems may be used to provide broadband wireless. WiFi is based on the IEEE 802.11 family of standards and is primarily a local area networking (LAN) technology designed to provide in building broadband coverage. Current WiFi systems based on IEEE 802.11a/g support a peak physical layer data rate of 54Mbps 3 and typically provide indoor coverage over a distance of 100 feet. WiFi has become the defacto standard for “last feet” broadband connectivity in homes, offices, and public hotspot locations. In the past couple of years, a number of municipalities and local communities around the world have taken the initiative to get WiFi systems deployed in outdoor settings to provide broadband access to city centers and metrozones as well as to rural and underserved areas. It is this application of WiFi that overlaps with the fixed and nomadic application space of WiMAX.

Metro area WiFi deployments rely on higher power transmitters that are deployed on lamp posts or building tops and radiating at or close to the maximum allowable power limits for operating in the license exempt band. Even with high power transmitters, WiFi systems can typically provide a coverage range of only about 1,000 feet from the access point. Consequently, metro WiFi applications require dense deployment of access points, which makes it impractical for large scale ubiquitous deployment. Nevertheless, they could be deployed to provide broadband access to hotzones within a city or community.

WiFi offers remarkably higher peak data rates than do 3G systems, primarily since it operates over a larger 20MHz bandwidth. The inefficient CSMA (carrier sense multiple access) protocol used by WiFi, along with the interference constraints of operating in the license exempt band, is likely to significantly reduce the capacity of outdoor WiFi systems. Further, WiFi systems are not designed to support high speed mobility. One significant advantage of WiFi over WiMAX and 3G is the wide availability of terminal devices. A vast majority of laptops shipped today have a built in WiFi interface. WiFi interfaces