Patent ID: 8774218

Claim:
A frame constructing method for use in a multi-hop wireless access network, comprising: determining Relay Stations (RSs) and Mobile Stations (MSs) in a Base Station (BS) domain; setting a Down Link (DL) sub-frame; setting an Up Link (UL) sub-frame; and constructing one frame based on the UL sub-frame and the DL sub-frame; and selecting a preamble not reserved for use by the MSs and configured to be used to synchronize the RSs with the BSs, wherein setting the DL sub-frame comprises: setting a frame header for synchronizing and controlling the MS, and setting a DL relay sub-frame field for DL relay information sent to the RS; and wherein setting the UL sub-frame comprises setting a UL relay sub-frame field for UL relay information sent from the RS; and wherein said DL sub-frame includes a relay sub-frame header, said relay sub-frame header including the preamble.