Patent ID: 8130672

Claim:
A data transmission method of a coordinator device of a data transmission system, the method comprising: forming a group comprising a plurality of reception stations to receive same data; transmitting data from the coordinator device to the formed group; after forming the group, allowing at least one another reception station to join the group by a join request thereof; determining with the coordinator device whether the at least one another reception station joins the group when the coordinator device receives the join request from the at least one another reception station; and performing a channel estimation with the coordinator device between the at least one another reception station that requests to join the group and the coordinator device that receives the join request, and selecting optimum channels with the coordinator device to transmit data to the group according to a result of the channel estimation, wherein the channel estimation is an estimation of at least one of data traffic, a travelling time, and unavailability, and wherein the coordinator device receives a data frame including a field that requests information on all groups included in a power line communication (PLC) cell from at least one of the plurality of reception stations of the formed group.