This thesis is carried out in the Communications Laboratory, Department of Electrical and Communications Engineering, Helsinki University of Technology, Espoo, Finland. I would like to take the opportunity to thank people who guided and supported me during this work.
I wish to express my deepest gratitude to my supervisor Professor Riku Jäntti for showing great interest in my work and for the guidance that he has given me. I also wish thank my instructor Lic. Tech. Boris Makarevitch for his valuable advice and guidance.
Thanks to my siblings and friends for their encouragement and mental support during my stay in Finland.
I am very grateful to my parents who have always given me their unconditional caring and support.
Mohammad Azizul Hasan 8th June, Espoo, Finland