In this paper, we provide a method to estimate the capacity of the wideband code division multiple access (WCDMA) scheme using High Altitude Platform Stations (HAPS), and demonstrate the results. This is to validate that the HAPS system is one of the most effective solutions to provide high quality wireless communication services, such as IMT-2000 services. We use a practical system model which describes the HAPS system most appropriately, and this leads to realistic estimation results. We estimate the reverse and forward link capacity of the HAPS WCDMA system and compare it to that of the terrestrial system. The estimation results show that the capacity of the HAPS WCDMA system is about 1.2-1.67 times larger than that of the terrestrial system.
For the successful deployment of the long term evolution (LTE)-based mobile satellite service, the price of a user terminal is one of the major factors. A user terminal for the LTE-based satellite communication needs to be implemented with a similar hardware size that is used for a terrestrial LTE user terminal. However, for quality of service provision, the satellite user terminal needs a larger size of memories than the terrestrial terminal does. This is very evident by considering that the N -channel stop and wait hybrid automatic repeat request requires proportionally increasing memory size by the propagation delay, resulting in unmanageable amount of memories in the satellite system. To resolve this problem, we propose an efficient memory management method at the user terminal when the size of memory is insufficient. The simulation results in this paper reveal that the proposed method can increase the throughput about 20.7% when a user terminal is operated under very low throughput condition with an insufficient memory size, compared with the case without memory management scheme. In addition, we show that the additional throughput gain can be obtained by the packet scheduling using the information of receiver memory status.Tae Chul Hong received the BS and MS degrees in Electrical and Electronics Engineering from Yonsei University in 2000 and 2003, respectively. He has worked for ETRI from 2003. He is currently a senior member of research staff at SW-SoC Open Platform Team of ETRI in Daejoen, Korea. His research interests include LTE-based mobile satellite system, stratospheric communications system, satellite MBMS, scheduling, and network QoS.
KunSeok Kang received the BS and MS degrees in School of Electronics and ElectricalEngineering from Kyungpook National University, Korea, in 1997 and 1999. He is currently a principal member of research staff at Satellite Wireless Convergence Research Department of ETRI in Daejoen, Korea, and has worked for the development of efficient transmission algorithms for satellite communications. His research interests include satellite communications, coding technique, and multicarrier transmission.
Bon-Jun Ku received the BS and MS degrees in School of Electronic and ElectricalEngineering from Kyungpook National University in 1995 and 1999, respectively. He received PhD degree in Electrical and Electronics Engineering from Chungbuk National University in 2010. He is currently a principal member of the research staff at Satellite Wireless Convergence Research Department of ETRI. His research interests include satellite communications system, stratospheric communications system, and antenna engineering.
Dae-Ig Chang received his BS and MS degrees in Electronics and Telecommunications
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