Performance of CDMA/PRMA as an Access Technique for Integrated Services in a UMTS High Altitude Platform System

High Altitude Platforms (HAPs) have gained a great interest in recent years. HAP systems will be global in nature but national in service provision. They will deliver IMT-2000 mobile and fixed wireless access using the proposed IMT-2000 terrestrial component radio transmission technologies and protocols. Under the above consideration, in this paper the performance of a MAC protocol based on the combination of the well-known Packet Reservation Multiple Access (PRMA) scheme with Code Division Multiple Access (CDMA) technologies in a Frequency Division Duplex (FDD) mode is studied, for a HAP operating at the 2 GHz frequency band at an altitude of 22 km. The impact of acknowledgement delay has been examined through computer simulations, along with the selection of suitable channel access functions (CAFs) to control the access of mobile users. Moreover the protocol performance is investigated in a cellular HAP environment and compared to that of a ground-based system. Finally, different traffic scenarios have been considered in order to investigate the access delay for non-real time traffic and the packet dropping performance for real time traffic.Nikolaos Batsios received his diploma degree in electrical & computer engineering (Telecommunication Division) from Aristotle University of Thessaloniki (Greece) in 2000. At the end of his studies, his diploma thesis was awarded from ERICSSON Hellas. He was also one of the six finalists of the IEEE Region 8 Student Paper Contest. He has worked as a Research Engineer in Space Engineering S.p.A. (Rome, Italy) and he was involved in ATB, ROBMOD and VIRTUOUS projects. Currently he is working in Intracom S.A. as Telecom Engineer. His research interests are in the field of satellite and terrestrial communication systems including physical layer design, medium access control layer architectures and protocols.Fotini-Niovi Pavlidou received the PhD degree in electrical engineering from the Aristotle University of Thessaloniki, Greece, in 1988 and the diploma in mechanical-electrical engineering in 1979 from the same institution. She is currently an associate professor at the Department of Electrical and Computer Engineering at the Aristotle University engaged in teaching for the under- and post-graduate program in the areas of mobile communications and telecommunications networks. Her research interests are in the field of mobile and personal communications, satellite and HAP communications, multiple access systems, routing and traffic flow in networks and QoS studies for multimedia applications over the Internet. She is involved in many national and international projects in these areas and she has chaired the European COST262 Action on Spread Spectrum Techniques. She has served as a member of the TPC of many IEEE/IEE conferences. She is a permanent reviewer for many international journals. She has published about 80 papers in refereed journals and conferences. She is a senior member of IEEE, currently chairing the joint IEEE VTS & AESS Chapter in Greece.