Method of forming a set of constellations which is intended to be used for transmitting data between a transmitter and a receiver

Transmission/reception equipment (3A) comprising forming means (400) for forming a set of constellations (Ci) of non-equiprobable points (ai,j) which is intended to be used for transmitting data, said forming means permitting to obtain for said set of constellations an average power (P) which is lower than or equal to a fixed threshold (Pmax), characterized in that said forming means comprise:

• approximating means (401) for forming a set of constellations based on approximated values of the powers of said constellations, said approximating means comprise means for forming each constellation independently while considering that its points are equiprobable,
• verifying means (402) for verifying whether the average real power of the set of constellations produced by said approximating means is lower than or equal to said threshold,
• readjusting means (403) for readjusting said set once or several times, if necessary, by suppressing one or several points in one or several constellations, so that the real average power of said set is lower than or equal to the fixed threshold.

A modem (3A) comprising means for forming a set of constellations of non-equiprobable points which is intended to be used for transmitting data, said forming means enabling to obtain for said set of constellations an average power which is lower than or equal to a fixed threshold, characterized in that said forming means comprise:

• approximating means (401) for forming a set of constellations based on approximated values of the powers of said constellations, said approximating means comprise means for forming each constellation independently while considering that its points are equiprobable,
• verifying means (402) for verifying whether the average real power of the set of constellations produced by said approximating means is lower than or equal to said threshold,
• readjusting means (403) for readjusting said set once or several times, if necessary, by suppressing one or various points in one or various constellations, so that the average power of said set is lower than or equal to the fixed threshold.

A data transmission system comprising at least transmission/reception equipment that includes forming means for forming a set of constellations of non-equiprobable points which is intended to be used for the transmission of data, said forming means enabling to obtain for said set of constellations an average power that is lower than or equal to a fixed threshold, characterized in that said forming means comprise:

• approximating means for independently forming each set of constellations by calculating approximated values of the powers of said constellations,
• verifying means for verifying whether the real average power of the set of constellations produced by said approximating means is lower than or equal to said threshold,
• readjusting means for readjusting said set once or several times, if necessary, by suppressing one or several points in one or several constellations, so that the real average power of said set is lower than or equal to the fixed threshold.

A modem (3A) comprising means for forming a set of constellations of non-equiprobable points which is intended to be used for transmitting data, said forming means enabling to obtain for said set of constellations an average power which is lower than or equal to a fixed threshold, characterized in that said forming means comprise:

• approximating means (401) for forming a set of constellations based on approximated values of the powers of said constellations,
• verifying means (402) for verifying whether the average real power of the set of constellations produced by said approximating means is lower than or equal to said threshold,
• readjusting means (403) for readjusting said set once or several times, if necessary, by suppressing one or various points in one or various constellations, so that the average power of said set is lower than or equal to the fixed threshold, said readjusting means comprise means for suppressing the point having the largest amplitude of the constellation that has the largest power until a real average power is obtained for said set which is lower than or equal to the fixed threshold.

A method of forming a set of constellations (Ci) of points (ai,j) that are not equiprobable, which is intended to be used for transmitting data between a transmitter (3A, 3B) and a receiver (3B, 3A), said method enabling to obtain for said set of constellations an average power (P) that is lower than or equal to a fixed threshold (Pmax) characterized, in that it comprise:

• a first step (20) consisting of forming a set of constellations based on approximate values (Pi) of the powers of said constellations,
• a second step (301, 302) consisting of verifying whether the average real power of the set of constellations obtained during the first step is lower than or equal to said threshold,
• a third step (303) consisting of readjusting said set once or several times, if necessary, by suppressing one or various points in one or various constellations, so that the real average power of said set is lower than or equal to the fixed threshold and suppressing the point that has the largest amplitude of the constellation that has the largest power, so as to obtain for said set a real average power that is lower than or equal to the fixed threshold.