A method of allocating a plurality of subbands to a plurality of streams of a multichannel link in a multicarrier modulation communications system, each stream being successively defined in a communications frame of said multichannel link by a number Mj of bits to be transmitted and a noise margin Γj. Each subband is associated with a normalized signal-to-noise ratio on the multichannel link. The subbands are classified in a specific order of the normalized signal-to-noise ratios. An energy Ei per subband is determined by a binary allocation algorithm. For each stream taken in the order of said frame, a number Nj of consecutive subbands taken in the order of normalized signal-to-noise ratios is allocated so that the sum of the numbers nij of bits in each subband allocated to each stream is equal to Mj where: M j = ∑ i = 1 N j ⁢ n ij and nij=log2(1+El·(SNR0)i/ΓJ).