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Satellite On-board Technologies for Next Generation Mobile Satellite Communication Systems
Mitsugi, Jin,Nakasuga, Yoshinori,Imaizumi, Yutaka,Suzuki, Yoshinori,Ueba, Masazumi 통신위성우주산업연구회 2003 Joint Conference on Satellite Communications Vol.2003 No.-
Next generation mobile satellite communications systems involve various types of traffic, including telephone, satellite SCADA and mobile hot spot traffic. The traffic will be broadband up to 1Gbps. To achieve such systems in the S band at affordable cost, innovations in satellite on-board technology will be required along with the adaptive modulation application. This paper introduces the concept of next generation mobile satellite communication and outline the requirements for the on-board equipment. It also presents a multi-beam feeder with a beam-group concept and an adaptive filter as enabling technology for such systems. The multi-beam feeder technique can provide sufficient satellite antenna gain all over the coverage area while enabling power to be focused on the needed beams. The communication capacity can be significantly enhanced with a meticulous resources assignment, which entails a complicated spectrum layout on the feeder link. The on-board adaptive filter allows the feeder link to be packed while maintaining the enhanced capacity.
A proposal on the configuration of AFC applicable to a wide range of frequency offset
Yamashita, Fumihiro,Nakasuga, Yoshinori,Mitsugi, Jin,Ueba, Masazumi 통신위성우주산업연구회 2002 Joint Conference on Satellite Communications Vol.2002 No.-
Future mobile satellite communications systems will provide services to fast vehicles. Thus, the signal received by the user terminals may experience a wide frequency shift away from the assigned frequency that is caused by the Doppler shift and insufficient precision of the Oscillator. This paper presents a new auto-frequency control (AFC) configuration that is capable of removing a large amount of frequency offset (about ${\pm}$0.6 fs, where fs means symbol rate of signal). The operational principle of the AFC is described, and its BER performance and initial acquisition time are evaluated via computer simulation.
Fundamental Characteristics of Onboard Bandwidth-Variable FFT Filter Bank
Yamashita, Fumihiro,Kazama, Hiroshi,Nakasuga, Yoshinori,Ueba, Masazumi 통신위성우주산업연구회 2000 Joint Conference on Satellite Communications Vol.2000 No.-
Voice service is currently the main service in mobile satellite communications, but in the future, there will be a demand for high-data rate services offering multimedia contents. Therefore, an onboard processor capable of handling services of various data rates is required. In the present study, it is assumed that a non-regenerative onboard processor will be used. The onboard processor must have functions to filter signals and convert their frequencies in a channel-by-channel manner. An FFT filter bank satisfies these requirements. However, the conventional onboard FFT filter bank is only applicable to signals of constant bit rate. Hence, the onboard bandwidth-variable filter bank that can handle many signals of various bit rates is proposed. The principle of operation of the bandwidth-variable FFT filter bank is described, then the BER performance of an FPGA-implemented design is evaluated.
Two-Tone CW Technique to Measure Difference in Transmission Time Between Radio Paths
USHIKUBOH,KONISHIM,NAKASUGAY,HORIKAWAK,USHIKUBO, H,KONISHI, M,NAKASUGA, Y,HORIKAWA, K 통신위성우주산업연구회 2005 Joint Conference on Satellite Communications Vol.2005 No.-
To achieve higher data rates and higher transmission capacity in wireless systems, efficient use of finite radio resources is an important technical issue. Measurement of the difference in the transmission time based on features of the paths helps to attain these goals. We propose a two-tone continuous wave (CW) technique to measure the difference in the transmission time between paths to achieve high data rate transmission in mobile satellite communication systems while efficiently using radio frequencies. The time difference between the paths is obtained by comparing phases detected from envelopes of the two-tone CWs passed through the measurement paths. This method simplifies the configuration and narrows the required bandwidth. The method can also be applied to a radio relay system including frequency conversion.