I am most grateful for her teaching and advice, not only the research
methodologies but also many other methodologies in life. I would not have achieved
this far and this thesis would not have been completed without all the support that I
have always received from her.
In addition, I am grateful for the teachers of telecommunication engineering:
Asst. Prof. Dr. Rangsan Wongsan, Dr. Rangsan Tongta, and others person for suggestions
and all their help.
Finally, I most gratefully acknowledge my parents and my friends for all their
support throughout the period of this research