Vertical handover, connection between wifi and 3G/4G broadband air cards
The Wi-Fi is now an ally of mobile broadband to save it from network saturation. It is a scenery closer and it begins to enter into the calculations of the major mobile operators. The technology that will help the 3G and 4G mobile network is called “vertical handover”, that is the transition of users across different networks (between Wi-Fi and 3G/4G or UMTS).
Different forms of vertical handover in the network are already used by some operators. South Korea’s SK Telecom makes between WiBro (local variant of WiMax) UMTS and CDMA2000. Rumors say that AT&T in the United States intends to adopt roaming between 3G and Wi-Fi
The IEEE organization is working to define a standard for vertical handover, the 802-21 between Wi-Fi, WiMax and 3G/4G. The horizontal handover is already used and is the transition from one cell to another within the same network (or between different networks using the same technology, such as in roaming).
Recently, efforts have multiplied between operators, academics and experts to reach a vertical handover efficiently managing to talk to different technologies. The reason is that there is an urgent need: in all developed countries the broadband mobile networks show signs of saturation. A remedy, already adopted in some countries (USA, Japan, United Kingdom) are the femtocell (small cellular base station, typically designed for use in a home) and picocell (wireless communication system typically covering a small area, such as in-building ) which installed by the user, are used to relieve the main operator (macrocell). In recent days, there was a historical overtaking in the United States: the number of femtocells has exceeded the number of the macrocell.
The weaknesses of this solution are the cost of the equipment and the need to have adequate backhaul (ie a fast connection to the rest of the network;now it happens through adsl-dsl). So it would be useful relieves traffic of mobile users on the wi-fi hot spot if they are present.The hot spots are in fact connected to a wired network, where bandwidth is less poor than mobile.
How it vertical handover works: software on the pc ’s user knows when there is a sufficient Wi-Fi signal, in that case it moves the connection on the network. Otherwise it uses the mobile network through UMTS/4G/3G air cards connected to a PC.
The challenge of the algorithm is to maintain a stable connection as the user moves from one network to another: this is the vertical handover. You do not realize they have switched from Wi-Fi to 3G or the opposite continuing to navigate normally. It can use any Wi-Fi hot spot that is authorized to have access. To succeed they had to overcome two problems of vertical handover: wi-fi delays authentication and the ping pong, the risk of passing continuously from one network to another when the Wi-Fi signal is weak. The paradox: wi-fi was always considered by operators the enemy that could undermine the boom in mobile data traffic. The boom is arrived, too strong, and now they go to the Wi-Fi to get help.
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Tagged With 802-21 protocol, vertical handover