Multicasting system and method for vehicular communication network

A roadside communication devices comprising:

• a communication unit configured to communicate with a plurality of vehicular communication devices and at least one neighboring roadside communication device;
• a beacon analysis unit configured to analyze beacon frames from the roadside communication device and the at least one neighboring roadside communication device when a slot allocation request is received from one of the vehicular communication devices;
• a determination unit configured to search for a period in which a slot has not been allocated by the roadside communication device and the at least one neighboring roadside communication device and determine whether a period for allocation of a slot to the vehicular communication device is present;
• and
• a slot allocation unit configured to allocate a slot period for multicasting by the vehicular communication device based on results of the determination of the determination unit;
• wherein the slot allocation unit, when the vehicular communication device enters a data communication area of the roadside communication device after a slot period has been allocated by the at least one neighboring roadside communication device, allocates information about the entry of the vehicular communication device to a period which belongs to a slot period of the beacon frame of the roadside communication device and which corresponds to the slot period allocated by the at least one neighboring roadside communication device.