Method of allocating subbands to streams of a multichannel link in a multicarrier modulation communications system

1. A method of allocating a plurality of subbands (SB i ) to a plurality of streams (FL j ) of a multichannel link in a multicarrier modulation communications system, each stream (FL j ) being successively defined in a communications frame of said multichannel link by a number M j of bits to be transmitted and a noise margin Γ j , wherein the method comprises the steps of:

a) associating with each subband (SB i ) a normalized signal-to-noise ratio (SNR 0 ) i on the multichannel link;

b) classifying the subbands (SB i ) in a specific order of the normalized signal-to-noise ratios (SNR 0 ) i ;

c) determining an energy E i per subband (SB i ) by means of a binary allocation algorithm;

d) allocating, for each stream (FL j ) taken in the order of said frame, a number N j of consecutive subbands (SB i ) taken in the order of normalized signal-to-noise ratios so that the sum of the numbers n ij of bits in each subband (SB i ) allocated to each stream (FL j ) is equal to M j , where:

M

j

=

∑

i

=

1

N

j

⁢

n

ij

the number n ij of bits being calculated from energy E i and normalized signal-to-noise ratio of i carrier and from noise margin Γ j of stream j.

2. The method according to claim 1 , wherein said specific order is the increasing normalized signal-to-noise ratios (SNR 0 ) i order.

3. The method according to claim 1 , wherein the step d) is repeated if the number of subbands allocated is less than the total number of subbands, increasing the number M k of bits to be transmitted in the frame by given streams (FL k ) of constant noise margin (Γ k ) by successive incrementations ΔM k =(M k /Σ k M k )·Δ, where Δ is a given increment, until all the subbands have been allocated.

4. The method according to claim 1 , wherein the step d) is repeated if the number of subbands allocated is less than the total number of subbands by successive dichotomies from an initial interval [M inf , M sup ] where M inf is equal to the total number Σ j M j of bits to be transmitted by all the streams (FL j ) and M sup is equal to the total number of bits to be transmitted in the frame by given streams (FL k ) with a noise margin lower than the minimum margin of said given streams, the number M k of bits to be transmitted in the frame by the given streams (FL k ) of constant noise margin (Γ k ) being increased on each dichotomy by an amount ΔM k =(M k /Σ k M k )·(M c −M inf ), where M c is the mid-point of the preceding dichotomy interval, until all the subbands have been allocated.

5. The method according to claim 1 , wherein the step d) is repeated if the number of subbands allocated is less than the total number of subbands with the noise margin (Γ 1 ) of given streams (FL i ) increased by successive incrementations by an increment (ΔF) until all the subbands have been allocated.

6. The method according to claim 1 , wherein the step d) is repeated if the number of subbands allocated is less than the total number of subbands, increasing the noise margin (Γ 1 ) of given streams (FL 1 ) by an amount calculated by successive dichotomies from an initial amount ΔΓ c =(ΔΓ inf +ΔΓ sup )/2, with ΔΓ inf =0 and ΔΓ sup equal to a sufficiently high value, until all the subbands have been allocated.

7. A computer program product comprising a non-transitory computer readable medium storing program code instructions for executing the steps of the method according to claim 1 , when said program is executed in a computer.

8. A subband hardware distribution module for a transmitter of a multichannel link, comprising means for implementing the method according to claim 1 .

9. A transmitter of a multichannel link, comprising the distribution module according to claim 8 .