what is the use of near field communication
Near-field communication NFC devices are used in contactless payment systems, similar to those used in credit cards and electronic ticket smartcards and allow mobile payment to replace/supplement these systems. This is sometimes referred to as NFC/CTLS (Contactless) or CTLS NFC. NFC is used for social networking, for sharing contacts, photos, videos or files.[2] NFC-enabled devices can act as electronic identity documents and keycards.[3] NFC offers a low-speed connection with simple setup that can be used to bootstrap more capable wireless connections.[3]
Cell site The maximum range of a mast (where it is not limited by interference with other masts nearby) depends on the same considerations.In any case the limiting factor is the ability of a low-powered personal cell phone to transmit back to the mast. As a rough guide, based on a tall mast and flat terrain, it may be possible to get between 50 and 70 km (30–45 miles). When the terrain is hilly, the maximum distance can vary from as little as 5 kilometres (3.1 mi) to 8 kilometres (5.0 mi) due to encroachment of intermediate objects into the wide center fresnel zone of the signal.[6] Depending on terrain and other circumstances, a GSM Tower can replace between 2 and 50 miles (80 km) of cabling for fixed wireless networks.[7] In addition, some technologies, such as GSM, have an additional absolute maximum range of 35 kilometres (22 mi), which is imposed by technical limitations. CDMA and IDEN have no such limit defined by timing.