Wi-Fi, or Wireless Fidelity, is a wireless local area network (WLAN) technology based on the Institute of Electrical and Electronics Engineers’ (IEEE) 802.11 family of standards, which includes 802.11a, b, g and n. There are several key differences between cellular and Wi-Fi. For example, Wi-Fi signals have a range of about 200 to 300 feet, while cellular GSM signals can travel for several miles. Wi-Fi also uses unlicensed spectrum, so unlike GSM, it has no inherent protection from interference.
Wi-Fi is used for a variety of applications. One of the most common is home and business Wireless Local Area Networks (WLANs). The other is “hotspots,” where users with an 802.11 PC card modem, hybrid cellular/Wi-Fi handset or laptop with an embedded modem get Internet access for free or for a fee. Hotspots are typically found in public areas such as airports and cafés.
Wireless operators frequently combine Wi-Fi with their 2G and/or 3G networks as a way to give their customers more options for accessing the Internet and data services. By offering adjunct Wi-Fi services, operators can leverage the installed base of Wi-Fi PC card modems and laptops with embedded 802.11 modems.
Wi-Fi also has become an important technology for the deployment of Unlicensed Mobile Access (UMA) services. These typically involve a handset that includes a cellular and Wi-Fi radio that can take advantage of a campus or in-home Wi-Fi router to place calls using VoIP technology that can then transfer seamlessly to a cellular network once outside the range of the Wi-Fi signal. Unlike VoIP calling, when UMA customers leave home or exit a Wi-Fi hotspot, their calls are seamlessly transferred to that operator’s GSM-HSPA wireless network. Calls also transfer from the wireless network onto Wi-Fi.
IP Multimedia Subsystem (IMS) is another system that is complementary to UMA and combines the elements of the cellular and Wi-Fi networks. While UMA is an access solution that provides roaming between cellular and Wi-Fi networks and helps provide connectivity inside buildings, IMS and the core network provide the whole service architecture. IMS is an industry standards-based platform for new services that is access technology agnostic. While UMA is a solution for the acute in-building coverage challenge, it is not a complete service platform and should not be compared with IMS as such.
IMS services can be delivered over any access technology, including DSL, cable, cellular and wireless technologies including Wi-Fi and WiMAX. Since IMS is access-agnostic, it can support UMA as well as other access methods, such as native IP access over Wi-Fi.
Wi-Fi is also used to deliver Internet Protocol Television (IPTV) into the home. Leading operators including TeliaSonera and Telenor (Sweden), and Belgacom SA (Belgium) offer gear to deliver HD IPTV streams over standard Wi-Fi throughout the home network, and others such as AT&T have reported trials. Using a device for 802.11n wireless connections instead of coaxial cable as the home’s main video distribution medium, transmissions of 30 Mbps to 50 Mbps are touted as guaranteed throughput for streaming video throughout a typical 2,500 to 3,000 square foot home. Some devices may support up to six HDTV IPTV streams running at 10 Mbps each.