Software-defined radio simplifies mobile phones

Mobile phones are getting more and more complicated. One reason is that a new radio is needed for each standard-GSM, 3G, and WLAN. A simpler solution, a radio that can be programmed to cover all standards, is now being developed at the Stringent Research Center at Linköping University in Sweden.

“We have come up with three concepts that, together, can reach the goal, the software-defined radio,” says the head of the Center, Professor Christer Svensson.

The three parts are:

1. Wideband Tunable Low-Noise Amplifier (LNA) for weak antenna signals.
2. A new type of Radio Frequency (RF) Sampling Receiver Front-End, devised to reshape the data with high carrier-wave frequency into a considerably lower data rate without losing useful information or mixing with disturbing signals. Unlike the conventional radio, it can receive signals with a wide range of carrier-wave frequencies and with different bandwidths. What’s unique is that the date rate has been slowed down before the analog-digital conversion, which otherwise would be extremely expensive and would use lots of currents.
3. A baseband processor that can be programmed for different standards. Today this is done by a circuit that is tailored only for a specific standard, like GSM.

The Low-Noise Amplifier and the RF Sampling Receiver Front-End exist already as prototypes in form of functional silicon chips.

Stringent (Strategic Integrated Electronic Systems Research) is Sweden’s largest electronics research center, with more than 50 researchers and graduate students from Divisions of Electronic Devices, Computer Engineering, Electronic Systems, and Embedded Systems. The mission of the Center is to convert complex ideas into silicon, to improve the efficiency of embedded systems, and to reduce developmental times. Basic funding is from the Swedish Foundation for Strategic Research.

The first year of operation has led to many other interesting research results including:

• New methods for allocating tasks in control computers, leading to enhanced efficiency and security for data processing (such as in cars).
• More efficient network protocols for network processors.
• New methods for design of efficient digital filters, which are useful in radio and satellite communication.