backhaul resource regions to the relay node through superior signals referring to fig1 the relay node rn sends pdcch 1212 to user equipment ue in the relay node cell just before receiving a downlink backhaul sub frame from the base station e g enb the base station may transmit the downlink backhaul sub frame by performing a frequency division multiplexing fdm for pdcch 1202 and pdsch 1203 of the user equipment in the macro cell this structure is for the purpose of maintaining compatibility with conventional lte systems in the fourth embodiment as well rf transmission reception switching time delays 1206 and 1207 are invoked respectively just before and just after reception of downlink backhaul resources in order to apply such a switching time delay to the backhaul sub frame the base station does not use the last ofdm symbol in the transmission of the downlink backhaul unlike the third embodiment the relay node in the fourth embodiment does not need to receive pdcch 1202 from the base station so a reception start timing of the relay node becomes the pdsch start timing of the downlink backhaul sub frame since there is no need of considering blank of n ofdm symbols in the third embodiment the last ofdm symbol for blank is set only in consideration of the aforesaid switching time delay such a blank resource is applied to the last ofdm symbol 1205 of backhaul rb resources in the downlink backhaul sub frame as shown in fig1 the relay node may regulate transmission timing with user equipment in the relay node cell depending on reception timing of the downlink backhaul sub frame from the base station a transmission process of the base.