The present invention relates to a method for communicating downlink and uplink sub-frames between a base station and at least one half duplex user equipment in a half duplex communication system. The method is characterised in that a scheduled synchronisation time (T" STUL ) is such that the beginning of the reception of the effective part of said uplink sub-frame (UL) is separated from the end of the transmission of the effective part of said first downlink sub-frame (DL1) by a duration which is equal to the difference between a single idle period (IP) and an incremental timing advance value (Δt A ), said single idle period (IP), having a duration greater than or equal to the summation of a downlink/uplink required minimum idle duration (T DLUL ) and a uplink/downlink required minimum idle duration (T ULDL ), is reserved in either the end of said first downlink sub-frame (DL 1 ), or the beginning of said uplink sub-frame (UL), or both, said incremental timing advance value (Δt A ) being greater than or equal to said uplink/downlink required minimum idle duration (T ULDL ) and lower than or equal to the difference between the duration of said single idle period (IP) and said downlink/uplink required minimum idle duration (T DLUL ).