Various communication systems may benefit from codebook methods and devices for multiple transmitters. For example, a codebook for four transmitters (4Tx) may provide further enhancement for downlink multiple-input multiple-output (DL-MIMO) systems. A method can include weighting a signal for transmission based on a precoder selected according to a feedback from a codebook, such as codebooks A, B, C, D, or E, described herein. The method can also include sending the weighted signal.