MC-CDMA downlink beamforming method with the weights applied to every element of the antenna array being different for every user and every frequency bin, the weights being adapted to maximise the signal to interference and noise ratio

摘要

The invention concerns a transmission method for transmitting a plurality of symbols from a base station of a MC-CDMA telecommunication system to a plurality (K) of users, each symbol (dk) to be transmitted to a user being spread with a coding sequence (ck(ℓ)) over a plurality (L) of carriers (ℓ) to produce a plurality of corresponding frequency components, said base station being provided with a plurality (M) of antenna elements (370). According to the invention, each frequency component produced by a symbol of a user (k) is weighted (320) by a plurality (M) of weighting complex coefficients (w*k(ℓ,m),m=1,..,M) to obtain a plurality (LM) of weighted frequency components (zmk(ℓ)), each weighting coefficient being relative to a user (k), a carrier (ℓ) and an antenna element (m) and said plurality of weighting coefficients being determined from estimates of the channel coefficients (hk(ℓ,m)) of the downlink transmission channels between each antenna element and each user for each carrier frequency, as well as the coding sequences of all users (ck(ℓ)), the transmit powers used for transmitting the symbols to the different users (Ptk) and the variance of noise affecting the received frequency components of the user's side.