Methods and systems for combined cyclic delay diversity and precoding of radio signals

Abstract

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 - 36 . (canceled) 
     
     
         37 . A method for transmitting information signals having a plurality of symbol vectors associated therewith on a radio channel, comprising:
 applying a channel-dependent first precoding matrix and cyclic delay diversity (CCD) matrix to the symbol vectors;   subsequently applying a second precoding matrix to obtain precoded symbol vectors;   further processing the precoded symbol vectors to obtain information signals; and   transmitting the information signals and transmitting signaling representing elements of the first precoding matrix.   
     
     
         38 . The method of  claim 37 , further comprising determining a frequency granularity for the signaling on the basis of a characteristic of the radio channel,
 wherein the signaling is transmitted at the determined frequency granularity.   
     
     
         39 . The method of  claim 38 , wherein the frequency granularity is set comparable to a frequency variation of the radio channel. 
     
     
         40 . The method of  claim 39 , wherein a frequency variation of the CCD matrix is finer than the frequency granularity for the signaling. 
     
     
         41 . The method of  claim 39 , wherein the frequency granularity for the signaling is maintained unchanged in response to an increase in a frequency variation of the CCD matrix. 
     
     
         42 . The method of  claim 38 , wherein said determining a frequency granularity disregards a frequency variation of the CCD matrix. 
     
     
         43 . The method of  claim 37 , further comprising forming the second precoding matrix in view of the first precoding matrix and/or CCD matrix. 
     
     
         44 . The method of  claim 37 , wherein the second precoding matrix is channel-dependent. 
     
     
         45 . 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:
 applying a channel-dependent first precoding matrix and cyclic delay diversity (CCD) matrix to the symbol vectors; 
 subsequently applying a second precoding matrix to obtain precoded symbol vectors; and 
 further processing the precoded symbol vectors to obtain information signals; 
   a transmit chain of elements for transmitting said information signals as well as signaling representing elements of the first precoding matrix using said plurality of physical transmit antennas.   
     
     
         46 . A method for equalizing information signals having a plurality of symbol vectors associated therewith, comprising:
 receiving over a radio channel information signals as well as signaling representing elements of a first precoding matrix;   forming a channel estimate associated with said received information signals by multiplying an initial channel estimate with a channel-dependent first precoding matrix and cyclic delay diversity (CCD) matrix, and subsequently multiplying with a second precoding matrix; and   equalizing said information signals using the channel estimate thus formed.   
     
     
         47 . The method of  claim 46 , wherein the signaling is received from a transmitting node with a frequency granularity which varies in accordance with a characteristic of the radio channel. 
     
     
         48 . The method of  claim 47 , wherein the frequency granularity varies in accordance with a frequency variation of the radio channel. 
     
     
         49 . The method of  claim 48 , wherein a frequency variation of the CCD matrix is finer than the frequency granularity for the signaling. 
     
     
         50 . The method of  claim 46 , wherein the received signaling further represents elements of the second precoding matrix, which is channel-dependent. 
     
     
         51 . A receiver for equalizing information signals having a plurality of symbol vectors associated therewith, comprising:
 a plurality of physical receive antennas;   a receive chain of elements for receiving said information signals as well as signaling representing elements of a channel-dependent first precoding matrix using said plurality of physical transmit antennas; and   a processor configured to:
 form a channel estimate associated with said received information signals by multiplying an initial channel estimate with the first precoding matrix and a cyclic delay diversity (CCD) matrix, and subsequently multiplying with a second precoding matrix; and 
 equalizing said information signals using the channel estimate thus formed.