1. Fujitsu Ltd., Kawasaki, Japan
2. Department of Electronics and Telecommunications, Politecnico di Torino, Turin, Italy
3. Department of Electronic and Electrical Engineering, University College London, London, U.K.
4. Nokia Bell Labs, Murray Hill, NJ, USA
5. Department of Electrical and Electronic Engineering, Aston University, Birmingham, U.K.
6. Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute, Berlin, Germany