Status Autumn 2016

Somerville was the first college at Oxford to install site-wide wi-fi back in 2011. We installed wi-fi access points (APs) throughout the college. By 2017 they were approaching end-of-life and were quickly becoming inadequate for the amount of internet traffic being carried on ever-increasing numbers of devices. It was agreed (and budgeted) to upgrade the APs in 2016 (IT Committee MT2016) .

Issues around the new APs

165 new APs were installed during the winter of 2017. It has transpired over the months since they were installed that Wi-Fi-coverage has not improved but in fact has declined with users losing connection to the internet or having no access at all. The situation has been mostly reported by graduate students but there is a widespread understanding amongst undergraduates that the Wi-Fi throughout the college is patchy and unreliable (as reported at the TT 2017 user group meeting). After a long period of intense investigation, experimentation and consultation with manufacturers, the problems have been diagnosed and we have come to a better understanding of the college’s requirements and the technology’s capabilities. The result is that we need to a) reposition nearly all the 165 APs that were installed last year and b) add a further 135 APs.

Why do we need to reposition APs?

Whilst the new points certainly do have significantly greater capacity and are more efficient, the technology and manufacture is very different and operational difficulties were discovered when they were positioned in the same locations as the old ones. For example, the old APs’ signal bled out through the backplate meaning that it gave a 360 degree coverage. The new ones have a more focussed and stronger signal but it is 180 degrees only. Therefore ceiling mounting gives a better coverage than positioning them on the wall as the old ones were (and where the new ones replaced them).

A separate issue has arisen with regard to ROQ East and West. Because of the proximity of the Maths building and the current location of our APs, the Maths wireless network is interfering with our network in ROQ East. With forthcoming temporary buildings due to be erected opposite West, the same issue is very likely to occur there too. In order to counteract this, APs need to be placed in each study bedroom and the APs in the corridors removed. Aerohive have very recently devised an AP for this purpose and it is proposed that we replace the corridor APs with the new room based ones. This will release 40 APs which we can use to provide extra capacity needed as a result of the survey

Why do we need more APs?

Network Frequency changes

Back in 2011/2 most devices within college would only have single wireless antenna installed in them and this would have been on the 2.4ghz network frequency. The 2.4ghz Wi-Fi spectrum was designed for long range and low data rates (i.e. a wide area covered but not many devices supported simultaneously). At that time we provisioned for just the 2.4ghz network and devices requiring simple email and website reading. Content such as video over Wi-Fi was not considered necessary then. The physical wireless APs, while adequate for such a network, were designed to work in the environment as it existed then.

Further expansion of wireless technology means there are now far more Wi-Fi enabled devices in the world all now using Wi-Fi. This has crowded the 2.4ghz network and as such client devices have developed to look for the newer and less congested 5ghz network – a jump from 90% 2.4ghz devices to 80% 5ghz enabled devices in the last 3 years (iPhone 4S was the last iPhone to only have 2.4ghz Wi-Fi).

The 5ghz spectrum is designed for short range and high data rates (i.e. less coverage but supports more devices). In addition wireless APs now offer quality-of-service to 5ghz devices in preference to the older networks.

Our wi-fi network now needs to be able to support both 2.4ghz devices and 5ghz ones. The coverage is different for each frequency and therefore more APs are needed to provide enough support for the shorter range but higher data support 5ghz network.

Greater bandwidth required

Wi-fi users not only have increasing numbers of devices that need supporting but they also use the Internet differently. In 2011, use was primarily email and web browsing. In 2017, most users will watch TV and films on their devices via streaming services (BBC iplayer, Netflix, etc), catch up with lecture videocasts and carry out Big Data research from their rooms. All of which requires a significantly larger amount of bandwidth than ever before. Moreover student numbers have increased significantly since 2011, as have conferences and bed and breakfast guests.

Thus pressure on the wifi network has magnified in four directions: the number of frequencies to cover, the number of devices each user brings to the college, the type of use made of the network and the number of individuals making use of the network t any one time. This understanding of our own needs and how the new APs work has come to light over the year since we put in the new APs on a like-for-like basis. While it would have been preferable to be in this position a year ago , it has become clear that we need to significantly boost the wifi network in order to provide an adequate service with some futureproofing in order to provide the service that users demand.

Going forward

A complete survey of the college has now been carried out by our network providers LAN3 and the hardware providers, Aerohive, to establish locations for the new APs that provide coverage fit for purpose. We are now ready to reposition around 165 APs and add a further 135 APs. LAN3 have undertaken to guarantee that this solution will provide the solution we need to establish a stable and sufficient wifi network

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