Cellular/satellite communications system with improved frequency re-use

A satellite communications system for relaying signals received from a ground station on a second frequency band by transmitting said signals on a first frequency band using a multiplicity of antenna elements, including:

• downconverting means for converting signals received at said second frequency to a corresponding baseband signal;
• demultiplexing means for time-division demultiplexing said corresponding baseband signal to obtain separate sample streams;
• separate modulator means corresponding to each of said separate sample streams for directly receiving said separate sample streams and for modulating a carrier at said first frequency band with said separate sample streams to generate corresponding modulated signals;
• transmit amplifier means for amplifying said modulated signals and transmitting said modulated signals using said multiple antenna elements;
• wherein said downconverting means comprises a quadrature downconverting means producing an I and a Q baseband signal.

A bidirectional satellite communications system comprising:

• a satellite including:
• a multiple element antenna having multiple antenna elements for receiving signals on a first frequency band and relaying said signals to a ground station on a second frequency band;
• downconverting means for converting signals received at each of said multiple antenna elements on said first frequency band to corresponding baseband signals;
• multiplexing means for directly receiving and time-division multiplexing said corresponding baseband signals to form a multiplexed sample stream;
• and
• modulator means for modulating a carrier in said second frequency band with said multiplexed sample stream and transmitting said modulated carrier to said ground station and
• a ground station including:
• downconverting means for converting signals received at said second frequency to a corresponding baseband signal;
• demultiplexing means, for time-division demultiplexing said corresponding baseband signal to obtain separate sample streams;
• modulator means for modulating a carrier with signals to generate corresponding modulated signals;
• transmit amplifier means for amplifying said modulated signals and transmitting said signals to said satellite;
• and
• wherein said multiplexing means and said demultiplexing means are synchronized.

A satellite communications system employing a multiple element antenna receiving signals on a first frequency band and relaying said signals to a ground station on a second frequency band including:

• downconverting means for converting signals received at each of said multiple antenna elements on said first frequency band to corresponding baseband signals;
• multiplexing means for directly receiving and time-division multiplexing said corresponding baseband signals to form a multiplexed sample stream;
• and
• modulator means for modulating a carrier in said second frequency band with said multiplexed sample stream and transmitting said modulated carrier to said ground station;
• wherein said multiplexing means comprises an I-signal multiplexing means and a Q-signal multiplexing means.

A satellite communications system employing a multiple element antenna receiving signals on a first frequency band and relaying said signals to a ground station on a second frequency band including:

• downconverting means for converting signals received at each of said multiple antenna elements on said first frequency band to corresponding baseband signals;
• multiplexing means for directly receiving and time-division multiplexing said corresponding baseband signals to form a multiplexed sample stream;
• and
• modulator means for modulating a carrier in said second frequency band with said multiplexed sample stream and transmitting said modulated carrier to said ground station;
• wherein said modulator means comprises a quadrature modulator means in which an I signal and a Q signal are impressed on respective carrier signals of nominally 90 degrees phase difference.

A satellite communications system for relaying signals received from a ground station on a second frequency band by transmitting said signals on a first frequency band using a multiplicity of antenna elements, including:

• downconverting means for converting signals received at said second frequency to a corresponding baseband signal;
• demultiplexing means for time-division demultiplexing said corresponding baseband signal to obtain separate sample streams;
• separate modulator means corresponding to each of said separate sample streams for directly receiving said separate sample streams and for modulating a carrier at said first frequency band with said separate sample streams to generate corresponding modulated signals;
• transmit amplifier means for amplifying said modulated signals and transmitting said modulated signals using said multiple antenna elements;
• wherein said demultiplexing means comprises an I-signal demultiplexing means and a Q-signal demultiplexing means and said separate sample streams comprise I and Q sample streams.

A communications system employing a satellite having a multiple element antenna having multiple antenna elements for receiving signals on a first frequency band and relaying said signals to a ground station on a second frequency band including:

• satellite downconverting means for converting signals received at each of said multiple antenna elements on said first frequency band to corresponding baseband signals;
• satellite multiplexing means for directly receiving and time-division multiplexing said corresponding baseband signals to form a multiplexed sample stream;
• satellite modulator means for modulating a carrier in said second frequency band with said multiplexed sample stream and transmitting said modulated carrier to said ground station;
• ground station receiving means for receiving said multiplexed sample stream from said satellite modulator means;
• ground station demultiplexing means for time-division demultiplexing said multiplexed sample stream to form separate sample streams;
• and
• ground station routing means for routing said separate sample streams to appropriate destination terminals.

A satellite communications system employing a multiple element antenna receiving signals on a first frequency band and relaying said signals to a ground station on a second frequency band including:

• downconverting means for converting signals received at each of said multiple antenna elements on said first frequency band to corresponding baseband signals;
• multiplexing means for directly receiving and time-division multiplexing said corresponding baseband signals to form a multiplexed sample stream;
• modulator means for modulating a carrier in said second frequency band with said multiplexed sample stream and transmitting said modulated carrier to said ground station;
• and
• a time-division demultiplexing means for processing time-division multiplexed signals received from said ground station, wherein said demultiplexing means and said multiplexing means use a same clock.