Systems and methods are described for robust scheduling of beam switching patterns in satellite communications systems. Embodiments operate in context of a hub-spoke satellite communications architecture having a number of gateway terminals servicing large numbers of user terminals over a number of spot beams. The satellite includes switching subsystems that distribute capacity to the user beams from multiple of the gateway terminals in a shared manner according to a beam group switching pattern. The beam group switching pattern is robustly formulated to continue distributing capacity during gateway outages (e.g., when one or two gateway terminals are temporarily non-operational due to rain fade, equipment failure, etc.). For example, the beam group switching pattern can be formulated to minimize worst-case degradation of capacity across user beams, to prioritize certain beams or beam groups, etc.

Robust beam switch scheduling

Conventional multibeam satellite communications systems ensure coverage of wide areas through multiple fixed beams where all users inside a beam share the same bandwidth. The authors consider a new and more flexible system where each user is assigned his own beam, and the users can be very geographically dispersed. This is achieved through the use of a large direct radiating array coupled with adaptive beamforming so as to reject interferences and to provide a maximal gain to the user of interest. New fast-converging adaptive beamforming algorithms are presented, which allow one to obtain good signal to interference and noise ratio with a number of snapshots much lower than the number of antennas in the array. These beamformers are evaluated on reference scenarios.

/pdf/adaptive-beamforming-for-large-arrays-in-satellite-12qfszgjza.pdf

Adaptive beamforming for large arrays in satellite communications systems with dispersed coverage

Conventional spot beam satellites receive return uplink beam signals that each correspond to a separate and unique return downlink beam. An embodiment of the invention allows flexible coverage areas by selectively attenuating and combining multiple return uplink beam signals and transmitting them on a single beam to a gateway terminal. This allows uplink capacity to be dynamically allocated amongst different uplink signals. Offered load in different beams can be predicted and used to set the attenuation values appropriately and the attenuation values may also be controlled remotely.

Flexible coverage areas for return link signals in a spot beam satellite communication system

This paper reviews the research and development on the phased array antennas (PAAs) for several applications in Japan First, the author shows the historical overview of the PAA for radar, satellite and mobile communication uses Then, the author introduces a millimeter-wave PAA, an optical beam forming, and an ultra wideband antenna element as modern applications of PAA systems

Progress of phased array systems in Japan

Optical Phased Array Using Multi Dither Heterodyning Technique for Receiving Optical Beam Former

Wideband Inter Networking engineering test and Demostration Satellite (WINDS) has been developed to realize high-data-rate satellite communication services for future multi-media applications. WINDS has Ka-band transmitting and receiving Active Phased Array Antennas (APAA) that can flexibly establish communiciation with any area by electronic beam scanning. we developed flight models of the APAA and verified its performance, including its radiation characteristics. This paper describes the design of the APAA and the development results of a flight model.

Yasuo Nakamura

Papers

Development results of a proto flight model of the Ka-band active phased array antenna for WINDS

Development of Ka-band Active Phased Array Antenna for WINDS

Development of Ka-band Active Phased Array Antenna for WINDS(WSANE2006)