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Cellular communications: Difference between revisions
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== Anatomy of a cell tower == | == Anatomy of a cell tower == | ||
[[File:Cell-tower2.jpeg|thumb|left|Photo of a cell tower, or 'cell site'. One circular point-to-point remote radio head can be seen near image bottom. This microwave antenna connects one cell site to another. Image courtesy Petr Kratochvil, | [[File:Cell-tower2.jpeg|thumb|left|Photo of a cell tower, or 'cell site'. One circular point-to-point remote radio head can be seen near image bottom. This microwave antenna connects one cell site to another. Image courtesy Petr Kratochvil, CC0 1.0 Public Domain.]] | ||
Antennae, and the equipment comprising a cellular base station, are typically mounted onto a radio mast, or other raised structure, like a building. Sometimes the structure is disguised as other things, like a tree, or as bricks, so as to blend in with the local environment. | Antennae, and the equipment comprising a cellular base station, are typically mounted onto a radio mast, or other raised structure, like a building. Sometimes the structure is disguised as other things, like a tree, or as bricks, so as to blend in with the local environment. | ||
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== Use of cellular infrastructure in disasters == | == Use of cellular infrastructure in disasters == | ||
As mobile phone adoption has rapidly increased, so has cellular communications infrastructure spread. In many parts of the developed world cell sites provide coverage across the majority of the landscape, whereas in economically poorer regions mobile data increasingly acts as the sole means of internet access in urban and rural areas. | As mobile phone adoption has rapidly increased, so has cellular communications infrastructure spread. In many parts of the developed world cell sites provide coverage across the majority of the landscape, whereas in economically poorer regions mobile data increasingly acts as the sole means of internet access in urban and rural areas. In 2021, 93% of the global population was covered by a mobile broadband network<ref>https://reliefweb.int/report/world/using-mobile-phone-technologies-disaster-risk-management-reflections-shear-june-2021</ref>. | ||
Due to this broad use, cellular communications are increasingly used as a broadcast medium for alerting as to a coming extreme environmental event. Further, during the preparation phase, the event phase and aftermath, cellular phones are often used to organise, stay in touch with loved ones and to give location and status updates to rescue teams. The use of realtime video and the sharing of photos and voice messages has proved vital for rescue efforts across many disaster events. | Due to this broad use, cellular communications are increasingly used as a broadcast medium for alerting as to a coming extreme environmental event. Further, during the preparation phase, the event phase and aftermath, cellular phones are often used to organise, stay in touch with loved ones and to give location and status updates to rescue teams. The use of realtime video and the sharing of photos and voice messages has proved vital for rescue efforts across many disaster events. | ||
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Sometimes however, even in cases cellular communications are available, or have been partially restored, internet access itself is not available via mobile data routing. This is due to the 'backhaul' connections being broken or impaired. In both Haiti's 2010 earthquake and Eastern Japan's 2011 earthquake, submarine cables were severely damaged, cutting off large populations from the Internet<ref>https://journals.sagepub.com/doi/full/10.1177/1550147719829960#table1-1550147719829960</ref>. This serves as an example where the use of Internet-dependent remote 3rd party applications or services on phones is not always to be relied upon. | Sometimes however, even in cases cellular communications are available, or have been partially restored, internet access itself is not available via mobile data routing. This is due to the 'backhaul' connections being broken or impaired. In both Haiti's 2010 earthquake and Eastern Japan's 2011 earthquake, submarine cables were severely damaged, cutting off large populations from the Internet<ref>https://journals.sagepub.com/doi/full/10.1177/1550147719829960#table1-1550147719829960</ref>. This serves as an example where the use of Internet-dependent remote 3rd party applications or services on phones is not always to be relied upon. | ||
Fuel is often in short supply during disaster events. It is thus plausible that the large diesel tanks at the base of many large cell sites used for generating backup power may be drained to fuel vehicles or electricity generators for other needs. | |||
== Failure of mobile phones during disaster events == | == Failure of mobile phones during disaster events == | ||
[[File:Nokia-phone.jpg|thumb|A Nokia GT-ET1200I 'dumbphone'.]] | [[File:Nokia-phone.jpg|thumb|120px|A Nokia GT-ET1200I 'dumbphone'.]] | ||
While modern smartphones provide many conveniences, much of their functionality is dependent on network connectivity. When mobile data or WiFi is unavailable, the device's use is limited to the on-phone features and applications that do not need Internet access. A common issue with smartphones in a disaster event is that they run out of battery, and so may not be usable into the 2nd day of an event. Another is that they suffer water or impact damage. For this reason it is wise to put your smartphone into low power mode early into a disaster event while disabling WiFi and any unnecessary idling applications. | |||
A ziplock bag can also protect your phone from water damage. When putting it into your go-bag, make sure it is easily accessible but also protected from impact damage where possible. Pack a pre-charged 'power bank' and tested cable with which to charge your phone. | |||
It is also good to have a fallback phone solely for texts and calls. This can be a very inexpensive 'dumbphone', many of which have battery life counted in several days, even weeks. | It is also good to have a fallback phone solely for texts and calls. This can be a very inexpensive 'dumbphone', many of which have battery life counted in several days, even weeks. A simple pre-pay SIM card can be put into that phone with enough credit for calls and texts. Note that even a SIM without credit will function for emergency calls. | ||
== Community operated cellular infrastructure == | == Community operated cellular infrastructure == | ||
[[File:Pink-cell-tower.jpg|thumb|Image of the Pink Cell Tower project, a cell site providing free voice and calls powered off a Rasberry Pi, BladeRF and the YateBTS GSM stack.]] | [[File:Pink-cell-tower.jpg|thumb|left|240px|Image of the Pink Cell Tower project, a cell site providing free voice and calls powered off a Rasberry Pi, BladeRF and the YateBTS GSM stack.]] | ||
Often it is victims of environmental and other disasters that are geographically closest to the damaged cellular communications infrastructure they depend upon, and yet even with sufficient knowledge at hand, civilians may not have the rights, credentials and rarefied tooling to attempt a repair that involves access to the base station component itself. | Often it is victims of environmental and other disasters that are geographically closest to the damaged cellular communications infrastructure they depend upon, and yet even with sufficient knowledge at hand, civilians may not have the rights, credentials and rarefied tooling to attempt a repair that involves access to the base station component itself. | ||
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* Coaxial cable and connectors | * Coaxial cable and connectors | ||
A pre-packaged example implementation of this is Pink Cell Tower by technologist and artist Julian Oliver and contributor to this wiki<ref>https://julianoliver.com/projects/pink-cell-tower/<ref>. An entire pre-configured 'ISO' disk image can be downloaded and flashed onto an SDcard, for use on a Raspberry Pi minicomputer that is connected to a BlareRF SDR, in turn connected to directional antennae on its transmit (TX) and receive (RX) ports. Optionally running from a truck batteries powered by solar panels, the project can also serve a simple website on the Raspberry Pi 4's built-in WiFi device, whereby important information can be served to those physically proximate to the tower itself. | A pre-packaged example implementation of this is Pink Cell Tower by technologist and artist Julian Oliver and contributor to this wiki<ref>https://julianoliver.com/projects/pink-cell-tower/</ref>. An entire pre-configured 'ISO' disk image can be downloaded and flashed onto an SDcard, for use on a Raspberry Pi minicomputer that is connected to a BlareRF SDR, in turn connected to directional antennae on its transmit (TX) and receive (RX) ports. Optionally running from a truck batteries powered by solar panels, the project can also serve a simple website on the Raspberry Pi 4's built-in WiFi device, whereby important information can be served to those physically proximate to the tower itself. | ||
It is important to check your local jurisdiction before setting up a cell site, as doing so is often in breach of local radio frequency allocation and usage laws. In an emergency such strictures may matter very little. | It is important to check your local jurisdiction before setting up a cell site, as doing so is often in breach of local radio frequency allocation and usage laws. In an emergency such strictures may matter very little. | ||