A method for configuring a downlink frame in a communication system, the method comprising: setting up a first region (202, 302, 204, 304) including allocation information of a data burst according to an amount of the data burst to be transmitted in a downlink frame, the first region (202, 302, 204, 304) being defined by slots, each slot being defined by a time domain symbol index and a frequency domain subchannel index; estimating a first transmission Protocol Data Unit/Packet Data Unit, PDU, according to scheduling priority; and transmitting the first PDU over a data burst allocation region (206, 306) in a remaining region except for the first region in the downlink frame, the data burst allocation region (206, 306) being defined by slots, each slot being defined by a time domain symbol index and a frequency domain subchannel index; wherein the data burst of said data burst allocation region includes at least one PDU having the same Modulation and Coding Scheme, MCS, level, with a previously transmitted PDU or is a data burst generated by concatenating PDUs of a same Mobile Station, MS; and wherein the data burst allocation region (206, 306) comprises a first sub-region (208, 308, 310, 312) comprising at least one slot over which a non-Hybrid Automatic Retransmit reQuest, non-HARQ, data burst is transmitted, and a second sub-region (212, 314) comprising at least one slot over which an HARQ data burst is transmitted; characterised by setting up the first region (202, 302, 204, 304) comprises determining a number of sub channels and a number of symbols included in a downlink MAP region (204, 304) within in the first region, and a number of data symbols included in the data burst allocation region (206, 306), based on a variable value which is incremented by one when the MCS level of the first PDU and the MCS level of the preceding PDU in the data burst allocation region (206, 306) are different, and not incremented when they are the same. setting up a first region (202, 302, 204, 304) including allocation information of a data burst according to an amount of the data burst to be transmitted in a downlink frame, the first region (202, 302, 204, 304) being defined by slots, each slot being defined by a time domain symbol index and a frequency domain subchannel index; estimating a first transmission Protocol Data Unit/Packet Data Unit, PDU, according to scheduling priority; and transmitting the first PDU over a data burst allocation region (206, 306) in a remaining region except for the first region in the downlink frame, the data burst allocation region (206, 306) being defined by slots, each slot being defined by a time domain symbol index and a frequency domain subchannel index; wherein the data burst of said data burst allocation region includes at least one PDU having the same Modulation and Coding Scheme, MCS, level, with a previously transmitted PDU or is a data burst generated by concatenating PDUs of a same Mobile Station, MS; and wherein the data burst allocation region (206, 306) comprises a first sub-region (208, 308, 310, 312) comprising at least one slot over which a non-Hybrid Automatic Retransmit reQuest, non-HARQ, data burst is transmitted, and a second sub-region (212, 314) comprising at least one slot over which an HARQ data burst is transmitted;