Method of pre-equalizing a data signal by time reversal in fdd

A device for pre-equalizing a data signal for a communicating entity referred to as an originating communicating entity, the entity having a set of originating antennas, said originating communicating entity being suitable for transmitting said signal in frequency division duplex to a destination communicating entity having a set of destination antennas, said device comprising means for:

• receiving a first pilot signal transmitted by a destination antenna;
• estimating a first impulse response of a first propagation channel between the destination antenna and a reference antenna;
• transmitting via an originating antenna, a second pilot sequence modulated by said first impulse response;
• estimating a composite impulse response of said first propagation channel and of a second propagation channel between the destination antenna and the originating antenna from a third pilot sequence transmitted by the destination antenna;
• and
• determining pre-equalization coefficients for the data signal from a combination of a set of composite impulse responses:,
• the means for emitting, receiving, and estimating being implemented iteratively for at least a portion of the set of destination antennas and at least a portion of the set of originating antennas.

A device for pre-equalizing a data signal for a communicating entity referred to as a destination communicating entity and having a set of destination antennas said destination communicating entity being suitable for receiving said data signal transmitted in frequency division duplex by an originating communicating entity having a set of originating antennas, said device comprising means for:

• transmitting via a destination antenna a first pilot sequence to the originating communicating entity;
• receiving a second pilot sequence transmitted by an originating antenna, said second sequence being modulated by a first impulse response of a first propagation channel between the destination antenna and a reference antenna;
• estimating a combined impulse response of said first propagation channel and of a second propagation channel between the originating antenna and the destination antenna;
• time reversing the combined impulse response;
• and
• transmitting a third pilot sequence modulated by said estimated time-reversed combined impulse response;
• the means for transmitting, receiving, estimating, and time reversing being implemented iteratively for at least a portion of the set of destination antennas and at least a portion of the set of originating antennas.

A radio communications system comprising:

• at least one originating communicating entity comprising a set of originating antennas and a first device configured to pre-equalize a data signal transmitted by the originating communicating entity in frequency division duplex to a destination communicating entity having a set of destination antennas, said first device comprising means for:
• receiving a first pilot signal transmitted by a destination antenna;
• estimating a first impulse response of a first propagation channel between the destination antenna and a reference antenna;
• transmitting via an originating antenna, a second pilot sequence modulated by said first impulse response;
• estimating a composite impulse response of said first propagation channel and of a second propagation channel between the destination antenna and the originating antenna from a third pilot sequence transmitted by the destination antenna;
• and
• determining pre-equalization coefficients for the data signal from a combination of a set of composite impulse responses:
• the means for emitting, receiving, and estimating being implemented iteratively for at least a portion of the set of destination antennas and at least a portion of the set of originating antennas;
• and
• at least one destination communicating entity referred to as the destination communicating entity and comprising a second device, said second device comprising means for:
• transmitting via the destination antenna the first pilot sequence to the originating communicating entity;
• receiving the second pilot sequence transmitted by the originating antenna, said second sequence being modulated by the first impulse response;
• estimating a combined impulse response of said first propagation channel and of the second propagation channel between the originating antenna and the destination antenna;
• time reversing the combined impulse response;
• and
• transmitting the third pilot sequence modulated by said estimated time-reversed combined impulse response;
• the means for transmitting, receiving, estimating, and time reversing being implemented iteratively for at least a portion of the set of destination antennas and at least a portion of the set of originating antennas.

A non-transitory data recording medium comprising a computer program recorded thereon, the program including software instructions for implementing a method of pre-equalizing a data signal transmitted in frequency division duplex by an originating communicating entity having a set of originating antennas to a destination communicating entity having a set of destination antennas, when the program is executed by the originating communicating entity, wherein the method comprises:

• a step of transmitting a first pilot sequence by a destination antenna;
• a step of the originating entity estimating a first impulse response of a first propagation channel between the destination antenna and a reference antenna of the set of originating antennas;
• an iterative step comprising the substeps of:
• an originating antenna transmitting a second pilot sequence modulated by said first impulse response;
• the destination entity estimating a combined impulse response of said first propagation channel and of a second propagation channel between the originating antenna and the destination antenna;
• time reversing said combined impulse response;
• the destination antenna transmitting a third pilot sequence modulated by said time-reversed combined impulse response;
• and
• estimating a composite impulse response of said first and second propagation channels from said modulated third pilot signal as received by the reference antenna;
• said iterative step being re-iterated for at least a portion of the set of originating antennas;
• said steps of transmitting a first pilot sequence, of estimating said first impulse response, and said iterative step being re-iterated for at least a portion of the set of destination antennas;
• and
• a step of determining pre-equalization coefficients for the data signal from a combination of a set of composite impulse responses.

A non-transitory data recording medium comprising a computer program recorded thereon, the program including software instructions for implementing a method for pre-equalizing a data signal for a destination communicating entity when the program is executed by the destination communicating entity, said destination communicating entity having a set of destination antennas and being suitable for receiving said data signal transmitted in frequency division duplex by an originating communicating entity having a set of originating antennas, wherein the method comprises:

• transmitting via a destination antenna a first pilot sequence to the originating communicating entity;
• receiving a second pilot sequence transmitted by an originating antenna, said second sequence being modulated by a first impulse response of a first propagation channel between the destination antenna and a reference antenna;
• estimating a combined impulse response of said first propagation channel and of a second propagation channel between the originating antenna and the destination antenna;
• time reversing the combined impulse response;
• and
• transmitting a third pilot sequence modulated by said estimated time-reversed combined impulse response;
• the means for transmitting, receiving, estimating, and time reversing being implemented iteratively for at least a portion of the set of destination antennas and at least a portion of the set of originating antennas.