Method and device for selecting an antenna for receipt of a multi-carrier signal

1. Method of evaluating received signals for a device comprising:

receiving a signal modulated simultaneously over a plurality of carriers, each carrier transporting a sequence of symbols, all the symbols transmitted simultaneously over all the carriers forming a series of symbols, separately evaluating the signal received by both a first antenna and a second antenna along a common evaluation path, the evaluation for the signal received at each of the first and second antennas being carried out for at least one evaluation period, wherein, for the evaluation period:

a confidence indicator is determined for the signal corresponding to each carrier and to each symbol received,

the symbols received are then transformed into a bitstream to which a stream of confidence indicators is allocated, each confidence indicator being allocated to a bit of a received symbol, the stream of confidence indicators being ordered identical to the bitstream,

sliding averages are then determined, the sliding averages being obtained from a number of confidence indicators from said stream of confidence indicators, this number being less than the total number of bits which can be transmitted simultaneously over the plurality of carriers, and

selecting one of the first and second antennas according to the separate evaluation for the signal received at each of the first and second antennas.

2. Method according to claim 1 , wherein the confidence indicators correspond to power measurements for the carriers carried out during the demodulation of the carriers.

3. Method according to claim 1 , wherein sliding averages are produced over a small number of confidence indicators, the small number being less than the total number of bits which can be transmitted simultaneously over the plurality of carriers, and in that the sliding averages serve to determine which is the strongest signal received at each of the first and second antennas.

4. Method according to claim 3 , wherein a criterion for evaluating a received signal corresponds to the minimum sliding average obtained for a signal in the evaluation period.

5. Method according to claim 4 , wherein the selected antenna corresponds to the antenna with the signal with the highest minimum sliding average.

6. Method according to claim 3 , wherein, for the signal received by both the first and second antennas:

the mean power for receiving the signal is measured during the evaluation time,

the minimum sliding average is determined during the evaluation time,

the mean receiving power is combined with the minimum sliding average, and in that the first or second antenna is selected as a function of the combination of the mean power with the minimum sliding average.

7. Method according to claim 1 , wherein the evaluation period corresponds to an evaluation burst and starts after at least one symbol has been received on each carrier.

8. Device for receiving a signal modulated over a plurality of carriers, each carrier transporting a sequence of symbols, all the symbols received simultaneously on the plurality of carriers forming a series of symbols, the device comprising:

a first antenna for receiving the signal;

a second antenna for receiving the signal;

an evaluation path;

a switch for selectively connecting the first and second antennas to the evaluation path;

the evaluation path comprising:

demodulation means for demodulating the symbols received by the various carriers;

transcoding means for transforming the series of symbols received into a bitstream received;

at least one means for determining a confidence indicator associated with each symbol for each carrier during the demodulation;

at least one layout means for transforming the confidence indicators determined for each cater into a stream of confidence indicators ordered identical to the bitstream, such that each confidence indicator is associated with a bit; and

means for determining a sliding average obtained from a number of confidence indicators from said stream of confidence indicators, this number being less than the total number of bits which can be transmitted simultaneously over the plurality of carriers;

the switch being controlled to select one of the first and second antennas according to a separate evaluation of the signal received at each of the first and second antennas.

9. Device according to claim 8 , wherein the confidence indicator is a measurement of the cater power, and in that the device comprises means for carrying out sliding averages on the confidence indicators.

10. Device according to claim 9 , wherein the evaluation path comprises a means for determining the minimum value of the sliding averages carried out during the separate evaluation.