The present disclosure relates to user communication devices and communication network devices, both arranged to support grouping of user communication devices in a communication network. One example user communication device determines a neighbor user communication device set comprising the user communication device and neighbor user communication devices, and determines, by communicating with the neighbor user communication devices of the neighbor user communication device set via D2D communication, a user communication device group that the user communication device joins. The communication network device receives information on a plurality of user communication device groups, determined by user communication devices in the communication network, and executes clustering on the plurality of user communication device groups.