Digital Signal Processing for Wireless Transmission

Our Group has been conducting research in transmission signal processing for wireless broadcasting since the early 1990's. We have built a solid expertise in OFDM wireless transmission in the mobile environment and have published several papers in this area. We have been actively involved in the development of the DAB, DMB and DAB+ standards both in the ITU-R and the WorldDMB Technical Committee.

Our expertise covers all major functions in the physical layer portion of radio communication systems, including modulation, synchronization, channel estimation and equalization, detection, and error correction. We have also expertise in MIMO (Multiple Input Multiple Output) antennas techniques to improve the performance of communication systems as well as extended knowledge of mobile channel characteristics and modeling.

Our capabilities include the simulation of complete communications systems in Matlab on powerful workstations to verify concepts and system performance as well as real time prototyping for lab and field testing.

Our Group has developed a number of proprietary technologies for the DAB/DMB/DAB+ and DVB-T/H/SH broadcast standards. These include:

• A robust OFDM synchronization scheme (CRC DABSync) for DAB/DMB/DAB+ portable and vehicular receivers that provides excellent performance in fast fading mobile channels.
• An advanced OFDM differential detection technique (CRC DABDetect) for DAB/DMB/DAB+ portable and vehicular receivers that counter the Doppler spread induced degradation in mobile receivers at high vehicle speeds. This technique is fully compatible with transmitted DAB/DMB/DAB+ signals and requires only additional signal processing in receivers.
• A robust OFDM synchronization scheme (CRC DVBSync) for portable and vehicular DVB-T/H/SH receivers that provides excellent performance in fast fading mobile channels.
• An advanced coherent OFDM detection technique (CRC DVBDetect) that includes proprietary channel estimation/equalization and ICI (Inter Carrier Interference) cancellation techniques for DVB-T/H/SH portable and vehicular receivers. Our approach provides excellent trade-off between implementation complexity and performance.

The above technologies can be licensed separately for incorporation in third parties' hardware or software-based receivers or licensed as part of our Software Defined Radio receivers. Some of these technologies can also be applied to other OFDM-based communication systems such as the 3GPP and LTE.

Software Defined Radio

A Software Defined Radio (SDR) system is a radio communications system where the baseband signal processing functions (i.e. synchronization, demodulation, detection, channel estimation/equalization, error corrections, audio/video decoding, etc.) are implemented in software running on a general purpose processor (GPP) or a digital signal processor (DSP) instead of in hardware on an Application Specific Integrated Circuit (ASIC) chipset. Typically, an SDR receiver consists of an hardware RF Front End to tune and downconvert the signal from radio frequency to baseband, an analog-to-digital (A/D) converter and a GPP or a DSP that performs the rest of the signal processing in software. In the future, with advances in A/D converters and GPP/DSP speeds, it is expected that some if not all of the downconversion process will be done in software as well. The main advantage of SDR over ASIC is that an SDR terminal can be easily reconfigured and re-used for new radio protocols or standards by simply loading new software.

Our Group is developing software defined radio implementation of radio and television broadcast standards. This include the DAB/DMB/DAB+, DVB-T/H as well as the ATSC and ATSC-M/H standards. Our work includes the following implementation of modulators as well as of receivers for these standards:

• CRC SoftDAB/DMB/DAB+ Modulator
• CRC SoftDVB-T/H Modulator
• CRC Basic SoftDAB/DMB/DAB+ Receiver
• CRC Advanced SoftDAB/DMB/DAB+ Receiver

Those technologies are commercially available through licensing.