Yun-Jeong Song

Development of mobile broadband interactive satellite access system for Ku/Ka band

It is difficult to implement the broadband satellite Internet and broadcasting service for mobile environment. The paper presents the design and implementation of a mobile broadband satellite access system. In case of the system design, mobile terminal service is considered a critical factor than fixed terminal services, such as resource management, antenna tracking, weak signal recovery. In the paper, mobile broadband interactive satellite access technology system (MoBISAT) is presented. The system network, which is composed of a star network, consists of time division multiplexing-based forward link and multi-frequency time division multiple access-based return link. The MoBISAT provides both Ku-band satellite TV and Ka-band high-speed Internet base on DVB-S/DVB-RCS standards to the passengers and crews for land, maritime and air vehicles. The key factors of hub and mobile terminal are addressed for the design and implementation of the MoBISAT. Especially, the design and implementation of the return link demodulation method, resource management scheme and mobile terminal structure including mobile antenna are described.

Performance analysis of channel impairment in high data rate satellite communication service

This paper presents a performance analysis for channel impairments that affect the service quality of a high data rate satellite communication system. Based on the modeling of group delay and nonlinear characteristics that severely affect the service quality, the system performances are analyzed for various data rate services via the Ka-band satellite channel. As the transmission data rate is increased, the degradations due to these channel impairments increase. The linear component of the group delay and the AM-AM component of the nonlinear characteristics severely affect the system performance.

Joint Carrier Recovery and Turbo Decoding Method for TDMA Burst MODEM Under Very Low SNRs

In this paper, we propose the enhanced carrier recovery algorithm for very low SNR environment. Especially, in order to increase an accuracy of residual frequency and phase offset estimation under very low SNR with constraints of power-limited communication system, it is achieved by comparing the phases between soft decision outputs of code symbols and the channel symbols at the each turbo decoding iteration. As the number of iteration increases, residual freq. and phase offset are compensated and thus the reliability of the soft decision output at next iteration is increased. In consequence, the complementary cooperation between iteration decoding and carrier recovery improves the final coded BER performance. The proposed techniques can fulfil the stringent up-link link budgets at Ka band by operating at very low SNR

Design of the robust demodulator for mobile broadband satellite Internet access system

In this paper, we propose a robust demodulator structure for mobile broadband satellite Internet access systems. Especially, in order to achieve good synchronization under very low SNR, a large frequency offset, and Doppler frequency offset, with the constraints of mobile satellite communication, we design a demodulator which has robust algorithms for carrier frequency recovery compared with the conventional algorithms. The proposed technique can fulfill the stringent up-link link budgets at Ka band by operating at very low SNR.