Recently there has been some public confusion relating to local authority ‘computer problems’ and the wireless links between various council offices.
In August 2012, in response to increased bandwidth demands by office staff, and increased security compliance guidelines from central government, the Council chose to upgrade the wireless connection between the buildings it owns. After examining the options, we chose a wireless solution that used the 5ghz frequency. This gave the Authority:
- Much better bandwidth by using 802.11n vs 802.11b standards – 300mbs vs 11mbs.
- A much more secure connection using WPA2 with AES encryption vs WPA
- Less interference from domestic wireless kit and other domestic appliances.
- More frequencies to choose from (21 non overlapping channels on 5ghz vs 3 non overlapping channels on 2.4ghz)
A link via VPN over broadband was examined, but this was discounted due to consistently poor internet speeds. Private circuits and leased lines were unfeasible due to price (£38,000 for three years). Entry level enterprise grade radios were also considered, but the cost was considered too great at the time (£4,000 per link).
The solution that is currently in place was delivered for a total cost of £1,400.
As part of the regulations governing the usage of the 5ghz spectrum1, all devices that use 5ghz have to comply with Dynamic Frequency Selection (DFS). This ensures that non-licensed 5ghz radios do not interfere with other devices on these frequencies. Many devices use these frequencies including aeronautical radionavigation2. DFS works by ensuring that these frequencies are clear from interference. Once the non-licensed radios detect a signal on the same frequency from one of the above services, the non-licensed radio has to drop its connection and reconnect on a different, un-used frequency – this causes the link to temporarily drop causing the IT problems. These drops were common last summer and an investigation was carried out comparing drop outs with landing times at the airport. Correlations were found with certain wind directions and drop outs. In July 2013, solutions were presented to management. It was decided at the time to not upgrade the system as the reorganisation and more efficient use of office space may make such upgrades unnecessary.