Research and Development of Satellite Switched TDMA System


Fig.1 INTELSAT VI Satellite

Antenna Beam Coverage of INTELSAT-VI Satellite

Fig.2 Antenna Beam Coverage of INTELSAT-VI Satellite

SS/TDMA System

Fig.3 SS/TDMA System

    Satellite Switched Time Division Multiple Access (SS/TDMA) is a highly efficient digital satellite communication system for multi-beam satellites. SS/TDMA system realizes efficient satellite operation by dynamic switching of multiple satellite spot beams, which is synchronized with burst transmission signals to multiple destinations by TDMA. Conducting research on essential subjects in SS/TDMA system, Takuro Muratani, Yasuhiko Ito and Takeshi Mizuike played a pioneering role in development of this technology to finally implement a commercial system through their continuing effort.

    The basic concept of SS/TDMA system was proposed already more than twenty years ago. Recognizing effectiveness of this technology, they initiated their research and development activities at an early period when technologies were still premature to implement the new concept of SS/TDMA. Takuro Muratani and Yasuhiko Ito first invented a solution algorithm to derive the most efficient sequence of switching pattern for given traffic demands among multiple spot beams. The paper they published not only provided a practical means to route given traffic demands with the shortest sequence of switching pattern but also attracted wide interest to the proposed mathematical model from a theoretical point of view. More than dozens of technical papers have been published on a basis of the proposed algorithm in the research areas of applied mathematics as well as communication engineering. Laying a foundation in this research area, their paper, which has been still cited frequently as a technical reference, is an exceptional achievement.

    Takuro Muratani, Yasuhiko Ito and Takeshi Mizuike continued a pioneering work to prove and demonstrate feasibility of essential technical subjects through development of a prototype on-board satellite switch matrix to implement SS/TDMA system, redundancy configuration and diagnostic techniques and synchronization control mechanism between TDMA reference stations and satellite switching. They played a leading role in development of the specification of INTELSAT SS/TDMA system, for which they also conducted a research on an operation planning method and developed an original control algorithm to take maximum advantage of the SS/TDMA system. The algorithm they developed is practically applicable as it takes account of both efficient assignment of traffic channels to satellite transponders and cost efficiency of earth station equipment.

    As the results of their effort and achievement, INTELSAT-VI satellite which was equipped with on-board SS/TDMA dynamic switch matrix was developed in 1989. For commercial implementation of the SS/TDMA networks, they developed a software system to generate channel assignment plan called burst time plan, which determines burst signal configuration and transmission timing. Implementing the original algorithms they proposed for generation of switching sequence and channel assignment in burst signals, the developed software is capable of planning an overall control and operation of the SS/TDMA network. Owing to this software system, in-orbit network testing was successfully conducted for the SS/TDMA networks via INTELSAT-VI satellites to finally realize commercial operation of large-scale SS/ TDMA networks accommodating tens of thousands of traffic channels.

    The SS/TDMA networks interconnecting dozens of earth stations via high quality digital satellite links are currently operating very successfully in both Atlantic and Indian Ocean Regions based on channel assignment and operation plans generated by this software. In Japan, a number of digital satellite links are provided to European countries by the SS/TDMA network in Indian Ocean Region via KDD Yamaguchi Earth Station.

    Laying the technical foundation for this new satellite communication system first in the world, they contributed to development of the commercial system through research of the essential technical subjects. Highly recognizing this technical accomplishment, the IEICE of Japan conferred the achievement award in 1996 to Takuro Muratani, Yasuhiko Ito and Takeshi Mizuike.


[1] Yasuhiko Ito, Yoshiyori Urano, Takuro Muratani, and Masahisa Yamaguchi、Analysis of A Switch Matrix for An SS/TDMA System、1977、Proceedings of IEEE, Vol.65, No.3, 1977
[2] Yasuhiki Ito and Takuro Muratni、Transponder Assignment and Scheduling for a Multi-Beam Satellite、1979、Transaction of IEICE, Vol.J62-B, No.4, 1979
[3] Takeshi Mizuike, Yasuhiko Ito, David J. Kennedy, and Lan N. Nguyen、Burst Scheduling Algorithms for SS/TDMA Systems、1991、IEEE Transactions on Communication, Vol.39, No.4, 1991
[4] Takeshi Mizuike, Yasuhiko Ito, Lan N. Nguyen, and Eijiro Maeda、Computer-Aided Planning of SS/TDMA Network Operation、1991、IEEE Journal on Selected Areas in Communications, Vol.9, No.1. 1991

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