Methods and Systems for Combined Cyclic Delay Diversity and Precoding of Radio Signals
In a transmitter or transceiver, signals can be precoded by multiplying symbol vectors with various matrices. For example, symbol vectors can be multiplied with a first column subset of unitary matrix which spreads symbols in the symbol vectors across virtual transmit antennas, a second diagonal matrix which changes a phase of the virtual transmit antennas, and a third precoding matrix which distributes the transmission across the transmit antennas.
1 . A method for transmitting information signals having a plurality of symbol vectors associated therewith on a radio channel comprising:
precoding said symbol vectors by multiplying said symbol vectors with:
a first column subset of a unitary matrix which spreads symbols in said symbol vectors across all virtual transmit antennas,
a second diagonal matrix which changes a phase of said virtual transmit antennas, and
a third precoding matrix which distributes transmit energy across physical transmit antennas,
further processing said precoded symbol vectors to generate said information signals, and
transmitting said information signals.
2 . The method according to claim 1 , wherein said physical transmit antennas are antenna ports.
3 . The method according to claim 1 , wherein said symbol vectors are first multiplied by said first column subset of unitary matrix, next multiplied by said second diagonal matrix and then multiplied by said third precoding matrix.
4 . The method according to claim 1 , wherein when transmitting using r layers, said third precoding matrix has l columns, said second diagonal matrix has l rows and l columns, said first column subset of unitary matrix has l rows and r columns, and said symbol vectors have r elements.
5 . The method according to claim 1 , wherein when transmitting using r layers, said third precoding matrix has r columns, said second diagonal matrix has r rows and r columns, said first column subset of unitary matrix is a unitary matrix having r rows and r columns, and said symbol vectors have r elements.
6 . The method according to claim 1 , wherein said step of further processing further comprises:
mapping precoded symbols to resource blocks to be transmitted via at least one of said transmit antennas; and
distributing said resource blocks over the resource element grid of an orthogonal frequency division multiplexing (OFDM) type of transmission.
7 . The method according to claim 1 , wherein phase shifts induced by said second diagonal matrix are varied with respect to a parameter that is a function of a position of the resource element used for transmitting a particular symbol vector.
8 . The method according to claim 7 , wherein said parameter is a subcarrier index.
9 . The method according to claim 7 , wherein said parameter is a data resource element index.
10 . The method according to claim 1 , wherein said first column subset of unitary matrix and said second diagonal matrix together exhibit the same structure as cyclic delay diversity (CDD) for spatial multiplexing when represented in the frequency domain.
11 . The method according to claim 1 , wherein said third precoding matrix is performing channel dependent precoding.
12 . A transmitter for transmitting information signals having a plurality of symbol vectors associated therewith on a radio channel comprising:
a plurality of physical transmit antennas;
a processor for precoding said symbol vectors by multiplying said symbol vectors with:
a first column subset of a unitary matrix which spreads symbols in said symbol vectors across all virtual transmit antennas,
a second diagonal matrix which changes a phase of said virtual transmit antennas, and
a third precoding matrix which distributes transmit energy across said physical transmit antennas, and for
further processing said precoded symbol vectors to generate said information signals; and
a transmit chain of elements for transmitting said information signals.
13 . The transmitter according to claim 12 , wherein said physical transmit antennas are antenna ports.
14 . The transmitter according to claim 12 , wherein said symbol vectors are first multiplied by said first column subset of unitary matrix, next multiplied by said second diagonal matrix and then multiplied by said third precoding matrix.
15 . The transmitter according to claim 12 , wherein when transmitting using r layers, said third precoding matrix has l columns, said second diagonal matrix has l rows and l columns, said first column subset of unitary matrix has l rows and r columns, and said symbol vectors have r elements.
16 . The transmitter according to claim 12 , wherein when transmitting using r layers, said third precoding matrix has r columns, said second diagonal matrix has r rows and r columns, said first column subset of unitary matrix is a unitary matrix having r rows and r columns, and said symbol vectors have r elements.
17 . The transmitter according to claim 12 , wherein said step of further processing further comprises:
mapping precoded symbols to resource blocks to be transmitted via at least one of said transmit antennas; and
distributing said resource blocks over the resource element grid of an orthogonal frequency division multiplexing (OFDM) type of transmission.
18 . The transmitter according to claim 12 , wherein phase shifts induced by said second diagonal matrix are varied with respect to a parameter that is a function of a position of the resource element used for transmitting a particular symbol vector.
19 . The transmitter according to claim 18 , wherein said parameter is a subcarrier index.
20 . The transmitter according to claim 18 , wherein said parameter is a data resource element index.
21 - 36 . (canceled)