From Mesh to UWB: Untangling the wireless future
Published: 16 Apr 2004 12:35 BST
MAN: Metropolitan Area Networks are essentially wireless wide area networks that are based on the IEEE's 802.2 standard. MANs are being rolled out in the UK by the likes of Cisco and Intel, which believes that WiMax and metropolitan networks will complement Wi-Fi to provide complete wireless access for urban workers connecting to LANs.
Metro networks offer blanket access to the Net throughout an area the size of a large city at speeds of 1.5 megabits per second -- compared to around 2Mbps for a typical Wi-Fi hot spot -- which functions only within a small area. MANs work by sending a signal from a cellular transmission site, which consumers access through a special chip in mobile devices.
Mesh radio: In conventional wireless networks, there are two basic models. First, a single base station transmits a signal to a single receiver (point to point) or a single base station transmits a signal to many receivers (point to multipoint). In a mesh network, a base station transmits to another base station, and the signal 'hops' to the next station in a relay (point to point to point). It's possible to cover an entire city quickly using mesh technology. It is also cheaper than building fibre, and offers speeds of up to 10Mbps -- not up to fibre, but significantly faster than DSL or cable solutions. However, there are some issues with mesh -- it's difficult to predict the strength of signal on mesh networks and it can be unreliable.
RFID: Radio frequency identification chips --- sometimes called smart tags -- work by emitting a radio signal that can be read by an electronic base station from up to 300 feet away. For example, Tesco attaches RFID tags to selected high-value items in its warehouses. Each tag emits a radio signal which is picked up by the base station and transmitted over a dedicated Radio Frequency (RF) network to a back-end database. This data can then be used to keep a close eye on stock levels. When they are combined with MEMS technology (micro-electronic mechanical systems), tags can also track their physical environment, including temperature -- making them invaluable where stock is perishable or where an audit trail is necessary.
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