VCM-OFDM technique for advanced space communications system with high spectral efficiency

• Published in: Acta astronautica 2016-11, Vol.128, p.385-391
• Main Authors: Li, Jionghui, Zhou, Qing, Xiong, Weiming, Zhang, Ying, Yao, Chen
• Format: Article
• Language: English
• Subjects: Architecture; Coding; Communication satellites; Communications systems; Computer simulation; Data transmission; Doppler effect; Efficiency; Links; Modulation; Orthogonal Frequency Division Multiplexing; Payloads; Satellite communications; Satellites; Spectra
• ISSN: 0094-5765; 1879-2030
• DOI: 10.1016/j.actaastro.2016.07.027

The development of precise scientific payloads brings higher demand on the efficiency of space communications system to transmit the increasing volume of scientific data. Aiming to this issue, Orthogonal Frequency Division Multiplexing (OFDM) is chosen for its inherent capability of high-rate data transmission. Further, considering the dynamic link condition due to satellite orbital motion, we propose a new technique which combines Variable Coding Modulation (VCM) with OFDM to enhance the communication link spectral efficiency with required transmission reliability. With VCM-OFDM technique, the channel coding and modulation mode can be variable with time according to the link conditions, in order to fit the link budget curve and maintain a relatively fixed link margin. Hence, link resource waste can be reduced and throughput can be remarkably improved. Considering that OFDM-based systems are sensitive to Doppler shifts/spread, the coding and modulation mode (CODMOD) selection should be optimized subject to this scenario. This paper introduces the architecture of near-earth space data transmission system based on VCM-OFDM technique. The Doppler influence is analyzed through simulation and the CODMOD selection algorithm is discussed. The results prove the high performance on spectral efficiency enhancement of VCM-OFDM by comparison with several existing alternative methods. •VCM-OFDM technique is proposed to support higher rate satellite data transmission.•A satellite data communication system architecture with VCM-OFDM is introduced.•System achieves higher spectral efficiency and less link resource waste.•Simulation proves 150% improvement of data throughput vs. traditional scheme.•Theoretical deduction and practical analysis for engineering aspect are included.