Method of transmitting and receiving a multi-carrier signal, and a transmitter, a receiver, a signal, and a computer program corresponding thereto

1. A method of transmitting a multi-carrier signal by a transmitter using at least two transmit antennas to at least one receiver using at least two receive antennas, the method comprising an obtaining step of obtaining an estimate of at least two transmission downlink channels, where a downlink channel is defined between one of said transmit antennas and one of said receive antennas;

the method comprising a transmission stage performing at least one iteration of the following steps, for the at least two downlink channels:

transmitting payload data over said downlink channel, while taking account of said downlink channel estimate;

receiving acknowledgment information of said payload data, wherein said acknowledgment information is transmitted by the receiver associated with said downlink channels in the form of an acknowledgment frame of a data link layer known as the MAC layer comprising a channel estimate packet carrying at least two sets of pilots, each associated with a distinct receive antenna of said receiver;

estimating the uplink channel for each of said uplink channels corresponding to each of said downlink channels on the basis of the sets of pilots carried by the said acknowledgment frame associated with the uplink channel;

determining calibration factors by comparing said estimates of the downlink channels with said estimates of the uplink channels corresponding to said downlink channels, and

updating downlink channel estimates on the basis of said uplink channel estimates and said calibration factors.

2. The transmission method according to claim 1 , wherein said step of estimating the uplink channel delivers an estimate of a first portion of the frequency response of said uplink channel, and wherein said method comprises a step of frequency and/or time interpolation enabling a second portion of said frequency response to be estimated from said first portion.

3. A non-transitory computer program product comprising instructions for implementing the method according to claim 1 when the program is executed by a processor.

4. A transmitter for transmitting a multi-carrier signal to at least one receiver using at least two receive antennas, said transmitter using at least two transmit antennas and comprising means for obtaining an estimate of at least two transmission downlink channels, where a downlink channel is defined between one of said transmit antennas and one of said receive antennas;

the transmitter further comprising the following means, activated at least once for at least two downlink channels in the form of one iteration:

means for transmitting payload data over said downlink channels, taking account of said downlink channel estimates;

means for receiving acknowledgment information of said payload data, wherein said acknowledgment information is transmitted by the receiver associated with said downlink channels, in the form of an acknowledgment frame of a data link layer known as the MAC layer comprising a channel estimate packet carrying at least two sets of pilots, each associated with a distinct receive antenna of said receiver;

means for estimating the uplink channel for each of said uplink channels corresponding to said downlink channels on the basis of said acknowledgment frame associated with the uplink channel;

means for determining calibration factors by comparing said estimates of the downlink channels with said estimates of the uplink channels corresponding to said downlink channels and

means for updating said downlink channel estimates on the basis of said uplink channel estimates and said calibration factors.

5. A reception method for receiving a signal corresponding to a multi-carrier signal transmitted by a transmitter using at least two transmit antennas and received by a receiver using at least two receiver antennas;

the method comprising at least one iteration of the following steps for at least two downlink channels, where a downlink channel is defined between one of said transmit antennas and one of said receive antennas:

receiving payload data on said downlink channels; and

generating and transmitting acknowledgment information acknowledging reception of said payload data and enabling said transmitter to estimate the uplink channels corresponding to said downlink channels, wherein said generation step generates said acknowledgment information in the form of an acknowledgment frame of a data link layer known as the MAC layer, and comprises a channel estimate packet having at least two sets of pilots, each associated with a distinct receive antenna of said receiver.

6. The reception method according to claim 5 , wherein the pilots of said sets of pilots are arranged in such a manner that, during said step of transmitting acknowledgment information, a pilot at a given frequency is transmitted at any given instant by a single one of said receive antennas.

7. The reception method according to claim 5 , wherein said transmission step transmits at least a first portion of said acknowledgment frame over a 40 MHz frequency band, and transmits a second portion of said acknowledgment frame over two 20 MHz frequency bands, where appropriate.

8. A non-transitory computer program product comprising instructions for implementing the method according to claim 5 when the program is executed by a processor.

9. A reception method for receiving a signal corresponding to a multi-carrier signal transmitted by a transmitter using at least two transmit antennas and received by a receiver using at least two receiver antennas;

the method comprising at least one iteration of the following steps for at least two downlink channels, where a downlink channel is defined between one of said transmit antennas and one of said receive antennas:

receiving payload data on said downlink channels; and

generating and transmitting acknowledgment information acknowledging reception of said payload data and enabling said transmitter to estimate the uplink channels corresponding to said downlink channels, wherein said generation step generates said acknowledgment information in the form of an acknowledgment frame of a data link layer known as the MAC layer, comprising a distinct channel estimate packet associated with each receive antenna of said receiver.

10. A receiver for receiving a signal corresponding to a multi-carrier signal transmitted by a transmitter using at least two transmit antennas, said receiver using at least two receive antennas;

the receiver comprising the following means that are activated in the form of an iteration at least once for at least two downlink channels, where a downlink channel is defined between one of said transmit antennas and one of said receive antennas:

means for receiving payload data on said downlink channels; and

means for generating acknowledgment information in the form of an acknowledgment frame of a data link layer known as the MAC layer comprising a channel estimate packet having at least two sets of pilots, each associated with a distinct receive antenna of said receiver and means for transmitting said acknowledgment information acknowledging reception of said payload data making it possible for said transmitter to estimate uplink channels corresponding to said downlink channels.