From bricks to smart dust
Professor John Dunlop and his colleagues at the University of Strathclyde have been working on wireless solutions for several decades, squeezing more and more out of the spectrum as the services and volume of traffic continue to multiply year after year. But even though we laugh about the first generation of cellphones – nicknamed "bricks" because they were so big and heavy – the slimline 3G devices we are using today will look just as bulky, when "smart dust" is sprinkled all over the world.…
If wireless telecoms continue to advance at the rate they are going today, telepathy will soon become available for £19.99 a month – or even "Pay-As-You-Think."
At least, that is the impression you could easily get from Professor John Dunlop, as he talks about the progress we have made since the age of the first mobile handset – the "brick" – and anticipates what is to come in the future.Science fiction writers would struggle to imagine some of the ideas in the minds of researchers. But for Dunlop and his colleagues, the challenge in the real world is the same today as ever – the available spectrum is finite, and even when analogue TV is switched off, freeing up more bandwidth, demand will soon swallow it up. Service providers will want to introduce more fancy services, and more consumers will demand instant access, everywhere and all the time. Then as soon as developers squeeze some more out of the spectrum, it will soon be consumed once again, and the same old problem will be with us again...
At the University of Strathclyde’s Department of Electronic and Electrical Engineering, researchers in the Mobile Communications Group have focused on this basic problem for decades, specialising in several key areas like error correction, in the struggle to accommodate more voice-only signals at the same time as data, and ensure that the signal is steady and clear. The department has also done important work in modelling base stations, helping service providers distribute their network for maximum coverage at minimum cost.
With emerging standards always a critical issue, Dunlop’s department was also involved in the "contest" between TDMA (Time Division Multiple Access) and CDMA (Code Division Multiple Access) – two different ways of using the radio spectrum to allow multiple users to share the same channel. Even though CDMA became the standard for third-generation systems, Strathclyde’s work on TDMA produced ideas which helped GSM (the Global System for Communications) to evolve, including a concept called "Link Adaptation," which improves the performance of wireless connections in poor signal conditions.
Link Adaptation helps the network "reach a technical compromise" between number of users and the amount of error protection used to maintain signal quality, and it continues to play a key role in the development of future solutions as well as today's wireless networks. GSM (the second-generation system) is still the most widely used system today and according to Dunlop, Link Adapation can also be used in CDMA and the emerging "fourth-generation" system, OFDMA (Orthogonal Frequency Division Multiple Access).
The pioneering work which the Department has done through the years in the packetisation of voice also continues to drive its more recent research. For example, in the 1980s, researchers worked out ways of sending voice over Ethernet cables, until then used exclusively for data. In solving many of the problems involved, they further developed their expertise in digital signal processing, and went on to focus on how to prevent bits of voice signals being lost during transmission due to fading – signal restoration and error correction.
For the last six years, Dunlop has focused a lot of his efforts on the Personal Digital Environment or PDE – the "bubble" we all move around in, containing all our digital connections. "From a single handset, users now have a host of devices which collaborate with each other," Dunlop explains. "They move around with us wherever we go, but not always together in physical terms, and this creates a number of problems, including implications for security."
As mobile services become ubiquitous and demand grows for instant access to data from any location, resource management – looking after large numbers of devices, all competing for spectrum - becomes increasingly important to the efficient delivery of services, and this is where Strathclyde has made a number of advances, including in security.Because it has such a strong background in the mobile arena, Dunlop's Department is also one of the partners in an initiative called Mobile VCE (Virtual Centre of Excellence) which brings together major mobile communications companies and universities in the UK. Started 12 years ago, the Mobile VCE is a collaborative project, funded by the government and industry, which anticipates the future of mobile communications and develops new technologies – and shares the results of research.
Out of this initiative, one of the breakthroughs achieved by Strathclyde is a new kind of concept, patented three years ago, called The Digital Marketplace, which enables subscribers to negotiate prices and quality of service from different service providers, competing with each other for service provision, using special software "agents" which they program with their individual preferences.
For example, you may need a lot of bandwidth for data-intensive access during a business trip from Monday to Wednesday, when you are willing to pay for high-quality service, then less sophisticated services from Thursday to Friday, when you’re back in the office, and very basic services like voice and texting over the weekend. In every case, the quality requirements are different, and you want the lowest tariff for the particular service you need – except when it comes to more critical work where you can’t afford slow speeds, lost signals or errors.
"The business models for consumers and service providers are changing," says Dunlop. As well as creating a new kind of user experience and intensifying competition, The Digital Marketplace will also have an impact on bandwidth and cooperation among different service providers.
For example, they may provide coverage for each other in remote areas where some users can’t get a signal – saving costs and improving connectivity for everyone concerned.
Following on from this, Dunlop is also concerned with another new concept called Cognitive Radio, which enables users to detect free spectrum and to negotiate with service providers to use their free spectrum or "digital real estate." This allows users to dynamically access available bandwidth. "Several years ago, this wasn't even thought about," says Dunlop, "but now it is becoming a reality."
Similarly, Strathclyde is doing research in Co-operative Radio, which reduces interference and helps users access spectrum by detecting other devices and "piggybacking" signals, so every phone effectively becomes a relaying base station, helping to create ad hoc networks and extending the core network into remote areas.
Strathclyde is also doing research into wireless sensor networks, where the challenges include reducing power consumption and extending battery life – in some cases, sending the sensor to sleep when it isn't required. Another promising technology, being developed at Strathclyde, is the switched beam antenna, so the sensor sends its signal in a particular direction, instead of in every direction, saving power and reducing interference.
Ultimately, this will lead to what is called "smart dust" – tiny sensors which detect and measure things like air pollution, weather conditions and earth tremors, etc. This smart dust will literally be scattered all over the world, and the airwaves will be full of signals, fighting for spectrum. Instead of putting up more and more radio masts, however, Dunlop says the challenge is to make the network smarter by reducing the range of transmissions, using concepts like Co-operative Radio so the signal can bounce from one device to the other.
In an industry where competition becomes more intense all the time, Dunlop and his colleagues at Strathclyde, together with their partners in initiatives like Mobile VCE, are showing that the way ahead will also be increased collaboration, not just between devices but also between different organisations and people.
On track to success
The Mobile Communications Group at Strathclyde has done work for a wide range of industries over the years, including transportation. For example, it had a pioneering role in the transmission of video pictures from trains using the then new GSM development known as high-speed circuit switched data transmission. This work was undertaken for London Underground in the 1990s using a form of compressed video transmission, to relay events occurring on the train to a control room in real time. Radio transmission in underground railway tunnels is a significant problem but it can be achieved using a technology known as the "leaky feeder."A further development on the public transport theme was undertaken with SNCF, who were considering the next generation of TGVs running at up to 500km/h. The Strathclyde team were part of a consortium which developed a new technique known as "switchover" which allowed multiple users on a train, moving at these high speeds, to enjoy normal cellular communications by rapidly switching a trunked radio link from the train to trackside receivers.
Mobile VCE (Virtual Centre of Excellence)
The network for networks
The Mobile VCE (Virtual Centre of Excellence) was set up in 1996 by a group of leading companies and academics, supported by the government, to advance research in mobile and personal communications technology. It currently has about 20 industrial members, including major manufacturers like Alcatel-Lucent, Nokia Siemens Networks, NEC, Samsung and Toshiba, and service providers such as Vodafone, BT and Orange. It has six full academic members, including the University of Edinburgh and the University of Strathclyde.
The main idea behind the partnership is to identify areas where research is needed to enable practical commercial solutions, producing intellectual property which all the industrial members can share, at the same time as strengthening the UK research base. In many cases, the research teams have representatives from several universities.
According to Chief Executive Dr Walter Tuttlebee, the Mobile VCE model will enable companies to access £2.5m-worth of research in 2009, at a cost of £43,500. "This gives them a ‘window on the future’ and lets them monitor the new technology threats and opportunities which would otherwise fall off the bottom of their budget list in the current economic climate," he added.Full members also get royalty-free access to resulting patents, recruitment, industry collaboration opportunities, government linkages and elective research – customised initiatives funded jointly by typically 3-6 member companies.Current projects include:- Delivery efficiency – optimising wireless resources to enable reductions in cost-per-bit of network connections- Ubiquitous services – overcoming barriers to the deployment of ubiquitous services in three key domains(user, network and service/content)- Instant Knowledge – managing the important privacy and security issues for new business services which exploit the power of personal communication devices
In 2009, a new research programme will launch, focusing on three major workstreams - Green Radio, Flexible (self-X) Networks and User Interactions to enable Breakthrough Services.
Describing the changes in the organisation over the last 12 years, Dr Tuttlebee said: "Mobile VCE has evolved hugely in that time. It has transformed from a UK-centric research project into a truly global and internationally respected research organisation. It has led many industry missions – to China, Korea, Japan, USA – and has MoUs with leading research institutions in those countries. Its technical focus always has included services and networks, as well as wireless, and this continues.
Today’s commercial pressures mean that today it is delivering more demonstrations of technology, as well as the more ‘traditional’ technical reports and patent filings."