This paper studies backoff-based priority schemes for IEEE 802.11 and the emerging IEEE 802.11e standard by differentiating the minimum backoff window size, the backoff window-increasing factor, and the retransmission limit. An analytical model is proposed to derive saturation throughputs, saturation delays, and frame dropping probabilities of different priority classes for all proposed priority schemes. Simulations are conducted to validate analytical results. The proposed priority schemes can be easily implemented, and results from this paper are beneficial in designing good priority parameters.