1. Electronic and Electrical Engineering Department, University of Strathclyde, Royal College Building, 204 George Street, Glasgow G1 1XW, UK
2. Electrical Engineering Department, University of Malawi-The Polytechnic, Chichiri, Blantyre, Malawi
3. T/ICT4D Laboratory, The Abdus Salam International Centre for Theoretical Physics, Strada Costiera, 11-34151 Trieste, Italy
4. ISAT Laboratory, University of Cape Town, 18 University Avenue, Rhodes Gift, Cape Town 7707, South Africa