ee.oulu.fi, jaakko.talvitieee.oulu.fi, aarne.mammelavtt.fiAssociate Professor Pentti Leppänen, Telecommunication Laboratory,
Department of Electrical Engineering, University of Oulu
Dr Jaakko Talvitie, Director of the Centre for Wireless Communications
Research Professor Aarne Mämmelä, VTT Electronics
pentti.leppanenee.oulu.fi, jaakko.talvitieee.oulu.fi, aarne.mammelavtt.fi
The demand for high-quality wireless communication services exceeded all expectations in the beginning of the 1990's. The demand will continue to grow in the next century. In addition to wireless telephony, wireless data and video transmission will also be required, which evidently will increase the data rate to several megabits per second. In wireless local area networks, the expected data rate is more than 100 Mbit/s. The research activities of the "Advanced Wireless Communication Systems and Signal Processing" group are focused on advanced wireless communication systems and on the advanced signal processing methods and architectures needed in the implementation of the above-mentioned systems. The group consists of 3 sub-groups:
The activities of the sub-groups together cover completely the lower layers of a generic communication system model, from the network and transmission system level down to the micro-architecture and logic gate levels.
The main goals of the group are
To support the development of the third generation mobile phone system (UMTS/IMT-2000), and future wireless local area networks and other systems to be used for fast wireless data transmission.
To analyze and design communication networks and protocols.
To develop channel measurement systems and channel models based on measurements.
To optimize communication systems, methods and algorithms based on the developed channel models. The channel models, and therefore systems, are developed for various different channels, for example channels with intentional interference (military applications), channels with multiple users (CDMA applications), and indoor-outdoor static channels (WLL applications).
To develop floating-point and bit-true models of receiver algorithms for different systems. The models include, for example multiuser detectors, channel decoders, synchronization algorithms, and cancellation of intentional interference.
To develop VHDL architecture models for the most important algorithms
To develop experimental systems to verify the theoretical results
To produce international publications, doctoral theses and licentiate theses.
The groups at the University of Oulu (TL and CWC) focus on system and algorithm level studies of wireless communication networks and methods. The interest is on spread-spectrum and CDMA techniques, and their application to wireless digital communication systems that will be used at the end of 1990's and early in the 21st century, as well as implementation of such systems by modern digital signal processing methods. Potential application areas are, for example, cellular CDMA and personal communication networks (PCN), military communication on VHF/UHF bands, indoor wireless communications, especially wireless local area networks (WLANs), and measurement systems for radio channel modelling based on spread-spectrum techniques.
The mission of the CWC and TL groups is scientific research and development of wireless communication methods and applications, and the transfer of the gained knowledge for the use of industry, defence forces and society. CWC focuses on commercial and civilian applications, whereas TL is specializing in military systems. The groups work in close co-operation, sharing the information and know-how relevant to both groups.
The main effort of the VTT group is in the research and development of algorithms and implementation architectures for digital receivers. The group's research and the development knowledge has been applied in several projects in which digital receiver algorithms and their architectures have been designed for a fast wireless WLAN (Wireless Local Area Network) system, power line DS spread-spectrum system, fast microwave radio, satellite UMTS and an experimental DS spread-spectrum system.
The research at VTT on the algorithmic level includes both optimal and suboptimal algorithms. The optimal algorithms are in most cases too complex for practical implementation. For this reason, low complexity suboptimal algorithms, which are based on the optimal ones and are suitable for implementation, are studied.
The design of implementation architectures is performed jointly with the design of algorithms. The work is focused on architectures suitable for ASIC implementation. For a given set of algorithms, the most promising architectures are selected and modelled by using VHDL language. VHDL architecture models are synthesized to gate level descriptions from which accurate estimates of the complexity (in number of gates) and the throughput (speed) of the ASIC can be achieved.