Digital port expansion for hybrid massive MIMO systems

An antenna system comprising:

• a down converter module having M·N inputs for receiving M·N digital transmit signal streams, each digital transmit signal stream representing a transmit signal for a different corresponding antenna element of an M×N array of antenna elements, said down converter module programmed to generate P digital transmit-beam signal streams from the M·N digital transmit signal streams, wherein each of the P digital transmit-beam signal streams is a corresponding linear combination of the M·N digital transmit signal streams;
• and
• an R×T Hybrid Massive MIMO system having R·T antenna elements, said R×T Hybrid Massive MIMO system configured to apply appropriate phase shifts in an analog domain that cause the R×T Hybrid Massive MIMO system to simultaneously generate a set of P independent, differently directed transmit beams and further configured to map each of the P digital transmit beam signal streams to a corresponding different one of the P independent, differently directed transmit beams of the set of P independent, differently directed transmit beams, wherein M, N, P, R and T are integers, wherein R·TM·N, and wherein P<M·N.

An antenna system comprising:

• an R×T Hybrid Massive MIMO system having R·T antenna elements, said R×T Hybrid Massive MIMO system configured to apply appropriate phase shifts in the analog domain that cause the R×T Hybrid Massive MIMO system to simultaneously generate P independent, differently directed receive beams for receiving P received beam signal streams, each received beam signal stream of the P received beam signal streams received over a different corresponding one of the P differently directed receive beams;
• an up-converter module having P inputs for receiving the P received beam signal streams from the R×T Hybrid Massive MIMO system, said up-converter module programmed to generate M·N digital, up-converted signal streams from the P received beam signal streams, wherein each of the M·N digital up-converted signal streams is a corresponding different linear combination of the P received beam signal streams and output the M·N digital up-converted signal streams for a base band unit, wherein M, N, P, R and T are integers, wherein R·TM·N, and wherein P<M·N.