Patent ID: 7154960

Claim:
In a multiple input/multiple output wireless system in which a plurality of transmitter antennas at a transmitter end of the system transmit a plurality of signals on separate channels to a plurality of receiver antennas at a receiver end of the system, a method comprising: determining, at the receiver end, instantaneous channel coefficients of each of the separate channels between the plurality of transmitter antennas and the plurality of receiver antennas; determining an average signal-to-noise ratio of the signals received by the receiver antennas; calculating, using the determined instantaneous channel coefficients and the determined average signal-to-noise ratio, the individual capacities of the transmitter antennas wherein the capacity of the k-th transmitter antenna, for k between 1 and t, is determined from the k-th term in log 2 ⁡ ( 1 + ρ t ⁢ h _ 1 + ( I + ρ t ⁢ ∑ i = 2 t ⁢ ⁢ h _ i ⁢ h _ i + ) - 1 ⁢ h _ 1 ) + log 2 ⁡ ( 1 + ρ t ⁢ h _ 2 + ( I + ρ t ⁢ ∑ i = 3 t ⁢ ⁢ h _ i ⁢ h _ i + ) - 1 ⁢ h _ 2 ) + log 2 ⁡ ( 1 + ρ t ⁢ h _ 3 + ⁡ ( I + ρ t ⁢ ∑ i = 4 t ⁢ ⁢ h _ i ⁢ h _ i + ) - 1 ⁢ h _ 3 ) + ⋯ + log 2 ⁡ ( 1 + ρ t ⁢ h _ t + ⁢ h _ t ) where t is the number of transmitter antennas, ρ is the average signal-to-noise ratio of the received signals, I is an identity matrix, h j is an i-th column for any i between 1 and t of a channel matrix containing the determined channel coefficients in which each coefficient h ij is the determined channel coefficient between the i-th transmitter antenna and the j-th receiver antenna, and h i + is the Hermitian transpose of h i ; and using the calculated individual capacities of the transmitter antennas, transmitting information back to the transmitter end so that when each transmitter antenna uses a determined data rate and modulation and coding scheme for each transmitter antenna, the calculated individual capacity of each transmitter antenna is not exceeded.