Text 55746, 60 rader
Skriven 2009-07-11 08:33:00 av TOM WALKER (1:123/140)
     Kommentar till en text av AUGUST ABOLINS
Ärende: Speed stick.
====================
AA>Unlike traditional wifi services, Roger's wireless service uses the cell-pho
AA>network of towers.  One of its advantages is that a connection does not requ
AA>line-of-sight - just reasonable proximity.  The closest cell tower is actual
AA>6 km away by road, but about 4km by "air".


Cell Range vaires wildy depending o nmany Factors. Here is a smal bit on
Cell Range.

*****

Cell site range

The working range of a cell site - the range within which mobile devices
can connect to it reliably is not a fixed figure. It will depend on a
number of factors, including

    * The frequency of signal in use (i.e. the underlying technology).
    * The transmitter's rated power.
    * The transmitter's size.
    * The array setup of panels may cause the transmitter to be
      directional or omni-directional.
    * It may also be limited by local geographical or regulatory factors
      and weather conditions.

Generally, in areas where there are enough cell sites to cover a wide
area, the range of each one will be set to:

    * Ensure there is enough overlap for "handover" to/from other sites
    (moving the signal for a mobile device from one cell site to
    another, for those technologies that can handle it - e.g. making a
    GSM phone call while in a car or train).
    * Ensure that the overlap area is not too large, to minimize
    interference problems with other sites.

In practice, cell sites are grouped in areas of high population density,
with the most potential users. Cell phone traffic through a single cell
mast is limited by the mast's capacity; there is a finite number of
calls that a mast can handle at once. This limitation is another factor
affecting the spacing of cell mast sites. In suburban areas, masts are
commonly spaced 1-2 miles apart and in dense urban areas, masts may be
as close as ¬-« mile apart. Cell masts always reserve part of their
available bandwidth for emergency calls.
Objects intruding into the fresnel zone between radio transmitters and
receivers can greatly impact signal strength.

The maximum range of a mast (where it is not limited by interference
with other masts nearby) depends on the same circumstances. Some
technologies, such as GSM, have a fixed maximum range of 40km (25
miles), which is imposed by technical limitations. CDMA and iDEN have no
built-in limit, but the limiting factor is really 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 is possible to get
between 50 to 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.
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 þ SLMR 2.1a þ 0  
 * Origin: Doc's Place BBS Fido Since 1991 docsplace.tzo.com (1:123/140)