Self-configuring multifunction mobile terminals
8/25/04
Software Defined Radios (SDRs) are mobile devices that can be reconfigured over the air. Users could download new services from network operators, and even have voice and email services provided by different networks. The SCOUT project has studied how SDRs will be regulated and marketed.
"From the high level perspective, mobile terminal evolution will drive network evolution," says Markus Dillinger of Siemens AG and SCOUT coordinator. "SDR Mobile terminals will evolve more and more capabilities. You could be connected, simultaneously, to a Wireless LAN network and UMTS or GPRS. I could check my emails whilst receiving phone calls."
The project has considered some of the big questions and started the debate in new areas. These include user, operator and regulator requirements in cellular and ad hoc networks, new business models for the reconfigurable mobile terminal, and procedures for managing the downloaded software on reconfigurable terminals.
"Telecom regulators have an interest in the deregulation of radio spectrum, which in turn could lead to new services and new ways of providing services, and which could drive the EU economy one step further," comments Dillinger."At the moment, frequency bands are allocated according to services, but one might consider refarming spectrum so that, for example, UMTS could operate in GSM frequency bands."
Achieving a coherent European view on frequency spectrum use and deregulation is difficult. Each country has its own issues and regulation policies are markedly different in, say, France, Germany and the UK. Nevertheless, one of the members of the SCOUT consortium was the German Regulator, Regulierungsbehörde für Telekommunikation und Post, which generated a questionnaire directed at manufacturers: what factors are important, what should be controlled by regulators, do regulators have a role to play vis-à-vis SDR? This has opened up the debate to a wider public and put SDR on the agenda.
More than a standard issue
"We've also considered so-called adaptive multiphase standards," adds Dillinger. "If you have a mobile terminal that can be reconfigured via the network, why should we have to wait for a fully-matured standard to be drawn up? You could reduce the time to market if a minimal standard was published and, as new parts were agreed, mobile terminals could download upgrades as required."
Agreement on the original GSM standard was relatively quick, because it was a small group of European interests. UMTS has taken longer to become adopted partly because discussions had to take place on a worldwide basis. "The next generation, 4G, may well take even longer unless the approach we take to standards improves. It's difficult to please everyone and, in practice, not all aspects of the standard [or specification] may be in place within the prescribed discussion period," comments Dillinger.
Cognitive radio is a concept that takes into account the users' preferences and immediate environment. "The mobile terminal would realise that you don't want to download large email attachments while you're in a metro train, and would only download the message headers," says Dillinger. "The terminal could also decide to use a UMTS connection rather than a Wireless LAN connection because it provided a better service or cheaper tariff at the user's location."
Research shows that one of the most commonly-voiced user preference is the ability to roam across networks. For the SDR, this means not only roaming from one service provider to another, but from one technology to another: Wireless LAN, GSM, GPRS, UMTS, etc. "Roaming would very much be the enabler for SDR flexibility," says Dillinger. "What's more, if there's a need, reconfigurability could be used to provide even more services to the end user."
What technology should be used in these SDR mobile terminals? According to Dillinger: "Well-known standards, such as GSM and UMTS, are sufficiently stable and well-understood to have been committed to ASIC [Application Specific Integrated Circuit] early on,” the programming of which is usually fixed at the time of manufacture. "But there are other devices, such as DSPs [Digital Signal Processors] and FPLAs [Field-programmable Logic Arrays] that are eminently suited to providing the processing power in an SDR because they can easily be reprogrammed."
The conflict between the classical standards approach and the IETF [Internet Engineering Task Force] still dominates how SDRs will be controlled. "To what extent should SDRs be supported by networks," says Dillinger. "At one extreme, you have UMTS and GSM networks that are controlled by operators, and at the other you have Wireless LAN networks that are privately owned and autonomous. We need to strike a balance that will, ultimately, stimulate economic growth. At the end of the day, however, you have to prove that spectrum deregulation is beneficial." |
