Although ultra-wideband transmission rates are very high in the physical layer, the bandwidth utilization efficiency is very low in the medium access control (MAC) layer. The bandwidth utilization efficiency can be improved and the quality of service for delay-sensitive variable bit rate traffic such as high rate motion picture experts group (MPEG)-4 traffic can be guaranteed by a simple and efficient algorithm that dynamically sets the burst size of the delayed-acknowledgement (Dly-ACK) based on the IEEE 802.15.3 standard. The burst size was adjusted in response to the wireless channel quality. Furthermore, the burst size was bounded by a maximum acknowledgement burst size setting and the remaining number of un-received blocks of a current supra-block. Simulation results show that the method achieves significant performance enhancement 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 division multiple access (TDMA) systems by using the block acknowledgement mechanism for delay sensitive traffic.