The present invention relates to a method for communicating between a primary station and at least one secondary station, comprising configuring each secondary station to search at least one of a plurality of search spaces having a first structure, said first structure consisting of at least a first number of resource sets having a first size, where at least one resource set might be used to transmit a message to the considered secondary station, changing the search space structure to a second structure different from the first structure in response to a signalling message.