In a system using spatial precoding, in the event that reliable channel state information is unavailable, a transmitting node artificially creates a randomization of the precoders applied to the transmitted signal. Different precoding vectors are applied to both transmitted data and demodulation reference signals for each of several groups of time-frequency resources, where the precoding vectors vary randomly or pseudo-randomly from each group of time-frequency resources to the next frequency-adjacent group or groups, or to the next time-adjacent group or groups, or both. In an LTE system in particular, this randomization of precoders can be applied at the resource-block level or, at the level of the Precoding Resource block Group (PRG), for example. Thus, the precoders applied to the transmitted signal vary from one PRG to the next, in a random or pseudo-random fashion.