An experimental mobile satellite communication network with an onboard packet switch system

An onboard switch makes satellite communications systems with a multi-beam structure more efficient. The Communications Research Laboratory has been studying mobile satellite communications networks, and developing an onboard packet switch. In this communications system, a compact mobile Earth station which can be installed in the mobile systems or easily carried anywhere is assumed. Its output power is 10 watts and it has a low gain antenna with less than 10 dBi. It is utilized to realize mobile satellite communications networks with a signal transmission rate of over several hundreds kilobits per second. The onboard packet switch has the function of bridges operating at the data link layer of the Open Systems Interconnect networking model. When the switch is located in a satellite, the satellite can be regarded as a central hub. One beam of the mobile links corresponds to one segment of the network. The bridges´ learning process is carried out between the beams, and the switching system builds and maintains tables with media access control address information. A proto-flight model of the onboard packet switch has already been developed. The performance test results show that the onboard packet switch is sufficient to meet the system requirements.