The work was led by Professor Andrew Nix from the CSN Group in the Department of Electrical and Electronic Engineering. Professor Nix explained: “Our new technique allows WiFi products to be rigorously and repeatedly analysed. Manufacturers can now optimise the speed and coverage of their products before they release them to their customers.
“Our co-operation with Farncombe has enabled a comprehensive WiFi test that is well-tailored to the needs of video service providers. This is vital given the sophistication of the latest chipsets and the complexity of in-home radio wave propagation.”
Dr Geoff Hilton, who co-developed the process and specialises in advanced antenna design, said: “Modern WiFi routers typically include between four and six internal antennas. The types of antenna, position, orientation and their proximity to other electronic components and the outer casing all make a significant difference. To predict the performance of a new product we need to measure how each of its antennas radiate in 3D space.”
Antenna characterisation is performed using an anechoic chamber, which is a special ‘echo free’ environment. The test unit is rotated for all angles while the response of each antenna is measured in turn. The end result is a set of complex ‘3D’ antenna patterns that describe how the signals radiate to and from each antenna into the home.
Professor Nix added: “Once we have all the antenna patterns, we combine them with channel data from our virtual reality models. Our test home is deliberately challenging, comprising ten rooms spread over three floors. Electromagnetic ray tracing is used to calculate how the WiFi signals flow, bounce and bend around the home between your wireless router and client, for example a tablet or mobile phone.
“Next we ‘move' the wireless router from room to room and predict its coverage and speed in all areas of the home. To reach our conclusion we analyse 1.44 million different WiFi links inside the property. WiFi speed and coverage is computed using the CSN Group's own 802.11n simulator, which has been developed over a 20 year period. The simulator supports some of the latest WiFi technologies, such as Eigen beam-forming with up to four antennas at the router.”
Professor Nix said: “We work with a wide range of customers but most of our projects are covered by non-disclosure agreements. We’re really pleased to be able to announce that the latest product through our optimisation process is the brand new Super Hub from Virgin Media.”
The University worked alongside the prime contractor, Farncombe, on a set of benchmark tests to ensure Virgin Media's new router offered best in class performance at 2.4GHz and 5GHz. Farncombe undertook empirical testing in real-world environments to support the University’s analysis. Farncombe’s specialist hardware design team also reviewed the product.
The Farncombe WiFI testing service brings together the University’s theoretical results with the empirical testing and hardware review in a single report delivered to the client.
Gary Marshall, Farncombe’s Managing Partner for Engineering Services, said “We are delighted that our collaboration with the University of Bristol has helped Virgin Media launch a market-leading product with its latest Super Hub. Our unique service has been developed hand-in-hand with the University of Bristol to deliver a world-class, truly independent assessment of WiFi product performance.”
Given the repeatability of the new process, competitor products from Sky, TalkTalk and BT were tested using identical wireless links. Virgin Media’s new Super Hub was found to typically be six to nine per cent better than the competition. In the 5GHz band the new Super Hub sets a new performance benchmark.
Professor Nix concluded: “Every few months we see a new WiFi product that raises the bar a little higher. Virgin Media’s new Super Hub is currently the best UK ISP supplied unit we’ve tested and it’s great to see our tests demonstrate another leap forward in technology.”