Patent ID: 7239659

Claim:
A method for a target communication unit to communicate to a source communication unit, knowledge of a channel comprising a plurality of subcarriers, the method comprising the steps of: determining a plurality of channel estimates for a plurality of subcarriers received from the source communication unit; producing a channel waveform based on the plurality of channel estimates; and communicating knowledge of the channel by transmitting the channel waveform to the source communication unit; wherein the channel waveform based on at least one of, Z u ⁡ ( k ) = β u ⁢ ∑ l = 1 M b ⁢ ∑ m = 1 M m , u ⁢ H ^ u , m , l ⁡ ( k ) ⁢ s u ⁡ ( k ) ⁢ exp ⁢ { - j2π ⁢ ⁢ k ⁡ ( m - 1 + ( l - 1 ) ⁢ M m , u ) / α u } ; Z u ⁡ ( k ) = β u ⁢ ∑ l = 1 M b ⁢ H ^ u , l ⁡ ( k ) ⁢ s u ⁡ ( k ) ⁢ exp ⁢ { - j2π ⁢ ⁢ k ⁡ ( l - 1 ) / α u } ; Z u ⁡ ( k ) = β u ⁢ ∑ l = 1 M b ⁢ ∑ m = 1 M m , u ⁢ H ^ u , m , l ⁡ ( k ) ⁢ q u ⁡ ( k ) ⁢ δ ⁡ ( ( k + 1 - ( l - 1 ) ⁢ M m , u - m ) M m , u ⁢ M b ) ; and Z u , m ⁡ ( k ) = β u ⁢ ∑ l = 1 M b ⁢ H ^ u , m , l ⁡ ( k ) ⁢ q u , m ⁡ ( k ) ⁢ δ ⁡ ( ( k + 1 - l ) M b ) ; where Ĥ u,m,l (k) is a channel estimate between the source communication unit transmit antenna of index l and a receive antenna of index m at the target communication unit for a subcarrier of index k; Ĥ u,l (k) is a channel estimate between a source communication unit transmit antenna of index l and a receive antenna at the target communication for a subcarrier of index k; δ(n) is one if n equals zero and is zero otherwise; β u is a scale factor; q u,m (k), q u,m (k), and s u (k) are known sequences; M m,u is a number of receive antennas at the target communication unit; α u is a shift factor; and M b is a number transmit antennas at the source communication unit.