In this paper, we propose two novel schemes, which prevent starvation of low priority traffic in the IEEE 802.11e MAC layer protocol, and at the same time ensure proper service differentiation and QoS to high priority traffic. A study of the starvation of low priority traffic in the IEEE 802.11e MAC layer protocol is presented. We also study the effectiveness of dynamic MAC parameters in achieving better performance in the IEEE 802.11e EDCF. The extensive simulation results show that the proposed schemes outperform the IEEE 802.11e EDCF and at the same time prevent starvation of low priority traffic. The proposed schemes are evaluated in a MANET through simulations to assess the impact of mobility on the performance of the proposed schemes