Patent ID: 8670500

Claim:
A method for transmitting signals at a transmitter of a Multi-Input Multi-Output (MIMO) system using a plurality of antennas, the method comprising: encoding input signals of an encoder to output (R) streams of signals, wherein (R) corresponds to a rank predetermined among {R1, R2, . . . , Rm}, wherein (m) is a predetermined integer number; performing a precoding on the (R) streams of signals at a precoder using a precoding matrix selected from a subset for (R) of a codebook, wherein the subset for (R) comprises (N R restrict ) precoding matrices, wherein (N R restrict ) is independently determined based on (R); and transmitting the precoded signals to a receiver, wherein: (N Ri restrict )≧(N Rj restrict ) when a subset for (Ri) comprises (N Ri restrict ) precoding matrices and a subset for (Rj) comprises (N Ri restrict ) precoding matrices; Ri and Rjε{R1, R2, . . . , Rm}; and Ri<Rj.