Although ultra-wideband transmission rates are very high in the physical layer, the bandwidth utili-zation efficiency is very low in the medium access control (MAC) layer. The bandwidth utilization efficiencycan be improved and the quality of service for delay-sensitive variable bit rate traffic such as high rate mo-tion picture experts group (MPEG)-4 traffic can be guaranteed by a simple and efficient algorithm that dy-namically sets the burst size of the delayed-acknowledgement (Dly-ACK) based on the IEEE 802.15.3 stan-dard. The burst size was adjusted in response to the wireless channel quality. Furthermore, the burst sizewas bounded by a maximum acknowledgement burst size setting and the remaining number of un-receivedblocks of a current supra-block. Simulation results show that the method achieves significant performanceenhancement in the job failure rate and throughput compared to immediate-acknowledgement (Imm-ACK)and other fixed burst size Dly-ACK schemes. This algorithm can also be applied in generalized time divisionmultiple access (TDMA) systems by using the block acknowledgement mechanism for delay sensitive traffic.