Editing Cell site (section)

=== Range ===

The working range of a cell site (the range which mobile devices connects reliably to the cell site) is not a fixed figure. It will depend on a number of factors, including, but not limited to: 
* Height of antenna over surrounding terrain ([[Line-of-sight propagation]]).
* The frequency of signal in use.
* The transmitter's rated power.
* The required uplink/downlink data rate of the subscriber's device<ref>J. Andrews, A. Gohsh (2007). ''Fundamentals of WiMAX'', p. 43</ref>
* The directional characteristics of the site antenna array.
* Reflection and absorption of radio energy by buildings or vegetation.
* It may also be limited by local geographical or regulatory factors and weather conditions.
* In addition there are timing limitations in some technologies (e.g., even in free space, GSM would be limited to 150&nbsp;km, with 180&nbsp;km being possible with special equipment)

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 site is limited by the base station's capacity; of -56 dBm signal there is a finite number of calls or data traffic that a base station can handle at once. This capacity limitation is commonly the factor that determines the spacing of cell mast sites. In suburban areas, masts are commonly spaced {{convert|2–3|km|mi|abbr=on}} apart and in dense urban areas, masts may be as close as 400–800 m apart.<ref>{{Cite web|url=https://www.electronicdesign.com/communications/understanding-small-cell-wireless-backhaul|title=Understanding Small-Cell Wireless Backhaul|date=3 April 2014|website=Electronic Design|access-date=4 December 2019|archive-date=9 August 2020|archive-url=https://web.archive.org/web/20200809003627/http://electronicdesign.com/communications/understanding-small-cell-wireless-backhaul|url-status=live}}</ref>

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 {{convert|50 and 70|km|mi|abbr=on}}. When the terrain is hilly, the maximum distance can vary from as little as {{convert|6 to 8|km|mi|abbr=on}} due to encroachment of intermediate objects into the wide center [[Fresnel zone]] of the signal.<ref>[http://www.arcx.com/sites/faq.htm Frequently Asked PCS Questions] undated, URL retrieved 14 August 2007. {{webarchive |url=https://web.archive.org/web/20060509174612/http://www.arcx.com/sites/faq.htm |date=9 May 2006 }}</ref> Depending on terrain and other circumstances, a GSM Tower can replace between {{convert|2 and 50|mi|km|0|abbr=on|order=flip}} of cabling for fixed wireless networks.<ref>[http://www.accel-networks.com/blog/2009/03/ntia-seeks-input-on-broadband-stimulus.html NTIA Seeks Input on Broadband Stimulus Money] undated, URL retrieved 3 March 2009. {{webarchive |url=https://web.archive.org/web/20091122053748/http://www.accel-networks.com/blog/2009/03/ntia-seeks-input-on-broadband-stimulus.html |date=22 November 2009 }}</ref> In addition, some technologies, such as GSM, have an additional absolute maximum range of {{convert|35|km|mi|abbr=on}}, which is imposed by [[Timing advance|technical limitations]]. CDMA and [[Integrated Digital Enhanced Network|IDEN]] have no such limit defined by timing.

==== Practical example of range ====
* 3G/4G/5G ([[5G NR frequency bands#Frequency Range 1|FR1]]) Mobile base station tower: it is technically possible to cover up to 50–150&nbsp;km. (Macrocell)<ref>{{Cite web|url=https://mobilenetworkguide.com.au/mobile_base_stations.html|title=Mobile Phone Base Stations, How do mobile base stations work, Mobile Base Stations in Australia, Cell Tower, Mobile Phone Tower|website=mobilenetworkguide.com.au|access-date=4 December 2019|archive-date=12 November 2020|archive-url=https://web.archive.org/web/20201112020205/https://mobilenetworkguide.com.au/mobile_base_stations.html|url-status=live}}</ref>
* 5G ([[5G NR frequency bands#Frequency Range 2|FR2]]) Mobile base station: the distances between the 5G base-station is about 250–300&nbsp;m, due to the use of [[Extremely high frequency|millimetre waves]].<ref>{{Cite web|url=https://spectrum.ieee.org/everything-you-need-to-know-about-5g|title=Full Page Reload|website=IEEE Spectrum: Technology, Engineering, and Science News|date=27 January 2017|access-date=4 June 2018|archive-date=15 January 2021|archive-url=https://web.archive.org/web/20210115035415/https://spectrum.ieee.org/video/telecom/wireless/everything-you-need-to-know-about-5g|url-status=live}}</ref>