The aggregation technique was defined by IEEE 802.11n, and used later by IEEE 802.11ac. This technique combines numerous packets into a single transmission. Hence, the throughput is improved since the overhead associated with each transmission is reduced. However, the delay is increased in the case of low rate application and large size of aggregated frame. In this paper, we propose new scheduling algorithm based on urgency delay and an adaptive frame aggregation technique to obtain an optimal trade-off between maximizing throughput and minimizing delay. Packets are scheduled based on Urgency Delay (UD) as well as Waiting Delay (WD). Packets having the lowest UD are firstly served to be included in the aggregated frame. Then, the payload size of aggregated frame will be adjusted based on the same metric of the first sub-frame. Simulation results prove that the serving delay and packet loss are widely reduced, and the average throughput is improved.