An efficient practical packet scheduling algorithm for high data rate cellular services has to tackle two challenges: bandwidth efficiency and fairness, which are conflicting with each other. Existing methods, e.g., HSDPA, usually fail to strike an optimal balance of the two aspects. Recently, a highly practical scheme called MTA-ISIR has been suggested. While the MTA-ISIR scheme is considered to be a promising method for practical use, we find that it can be further improved. In this paper, we propose a new approach in which the power level threshold used for handling the fairness is dynamically adjusted. Our new approach also makes use of the "opportunistic scheduling" concept which enables the scheduler to optimize the bandwidth efficiency without sacrificing fairness. Simulation results indicate that our proposed method outperforms MTAISIR in various practical situations.