Method and system for transmitting downstream data by relay

The present invention discloses a system for transmission of downlink data by the relay, comprising an evolved Node B, and the relay terminal, the evolved Node B, for determining based on the relay downlink transmit power for the terminal the terminal power parameter, the power parameter and notification to the terminal; the relay, for transmission power according to the downlink signals transmitted to the terminal; a terminal, according to the power parameter received from the evolved node B and / or the relay signal demodulated. The present invention resides in the LTE-A system for relaying the scene, according to the characteristics of the relay design which is suitable for relaying transmit power and transmission parameter setting methods, adapt to the characteristics of the relay, to improve the transmission performance of the system, and It solves the problem of transmitting power relay node set.