A shared control channel structure includes at least one control channel to be allocated at least to a user for at least one of uplink and downlink directions in a network, which the at least one control channel is arranged as at least a part of a modular structure comprising of modular code blocks on at least two different sizes. One of such modular structures may be represented as a tree structure in particular, where each of the modular code blocks define one node of the tree, respectively.