Network apparatus for channel access in contention free period

PURPOSE: A network device accessing a channel in a non-competition section is provided to allocate a time slot of remaining non-competition sections to the data transmission of a terminal according to priority by changing a guarantee time slot in a fixed non-competition section. CONSTITUTION: A coordinator(110) fixes a non-competition section in a frame at a preset size. The coordinator sets a GTS(Guarantee Time slot) in the fixed non-competition section to allocate the same. A terminal group forms the coordinator and a network. The terminal group includes one or more terminals. The terminals requests the GTS to the coordinator to transmit data to the GTS. [Reference numerals] (110) Coordinator; (121) First terminal; (122) Second terminal; (AA,BB) Beacon_i transmission; (CC) GTS allocation request; (DD,II,JJ) ACK transmission; (EE,FF) Beacon_(i+1) transmission; (GG) Data transmission by Poll; (HH) Data transmission