4G Networks Could Be Knocked Offline by Solar Storms - Warns UK Report
A report into how the UK would cope with a "solar superstorm" -- a huge outburst of radiation from the Sun has warned that future 4G networks are more vulnerable to being knocked offline than current GSM and 3G networks.
An expert panel for the Royal Academy of Engineering studied the UK in particuar, and found that in general the UK is well adapted to deal with the sort of electromagnetic disruption caused by the mass solar eruption.
One of the key issues is the reliance of mobile networks on timer signals sent from GPS/GNSS satellite systems. While the satellites themselves should survive the solar storm, disturbances in the ionosphere could block their signals for several days.
The report said that "all terrestrial mobile communication networks with critical resiliency requirements should also be able to operate without GNSS timing for periods up to three days."
The use of GNSS (currently GPS) at base stations varies significantly according to the wireless technology employed. The 3G-based systems used in the UK were specifically designed not to require GPS support, by avoiding the need for synchronous operation between adjacent base stations.
Also, the current planned FDD-LTE based 4G networks avoid the need for GPS based synchronization. However, TD-LTE can require GPS signals to function, and the report notes that while TD-LTE is likely to lag the more conventional LTE services, it could be deployed, and if so, reliance on GPS signals needs to be considered.
In addition mobile phone based GPS systems would be affected which would impact on location based services - most importantly when used by the emergency services, but as will be seen below, cell based location systems might not be a reliable alternative.
The study concluded that as it stands today, the UK public mobile systems should be largely unaffected by GNSS disruption during a solar superstorm.
The other area of concern during a solar superstorm is radio noise in the atmosphere affecting base stations. Looking into this issue, the researchers concluded that in general, the problems would be limited to evenings and mornings, when the sun is facing head on to antennas mounted on base stations - and then only in the sector of the cell between the tower and the sun.
The study concluded that the UK's commercial cellular communications networks are currently much more resilient to the effects of a superstorm than those deployed in a number of other countries (including the USA) since they are not reliant on GPS. Solar radio bursts have been identified as a potential problem, but only for parts of the network facing the Sun at dawn and dusk. The Academy said that it believes that this is an acceptable risk given that each burst will only last ~20 minutes.
It did however have concerns about TETRA based radio networks used largely by the emergency services as they rely on GPS timing signals. If TETRA networks were knocked off-line, then the emergency services may have to rely on commercial mobile networks, which themselves would be likely be both disrupted in places, but also congested due to the natural tendency for people to phone each other during emergencies.
The report recommended that all terrestrial mobile communication networks with critical resiliency requirements should also be able to operate without GNSS timing for periods up to three days. This should particularly include upgrades to the network including those associated with the new 4G licenses where these are used for critical purposes and upgrades to the emergency services communications networks.
On the web: Royal Academy of Engineering