<p>Modern multimedia applications, such as video streaming and VoIP, are highly sensitive to throughput and delay, requiring accurate performance evaluation to ensure stringent Quality of Service (QoS) guarantees. The packet fragmentation mechanism, proposed by the IEEE working group to enhance the MAC (Medium Access Control) sublayer of the IEEE 802.11 standard in error-prone channels, has recently generated interest in studying its impact on access mechanism performance, including the Enhanced Distributed Channel Access (EDCA) mechanism of IEEE 802.11e networks. However, existing analytical evaluation models exhibit several anomalies, the most significant being the inadequate adaptation of Bianchi’s calculation for the average time slot length. Consequently, these models do not accurately reflect the expected performance in an imperfect channel. This paper proposes an analytical model capable of precisely evaluating the effect of fragmentation in an imperfect IEEE 802.11e-EDCA network, considering both throughput and, to the best of our knowledge, access delay. Analytical results derived from our model predict significant performance improvements compared to the existing model and transmission without fragmentation, with access delay reductions up to 64.25% and 65.15% respectively for video and voice categories under challenging channel conditions. Based on these analytical findings, a practical adaptive fragmentation policy is also derived, providing a direct mapping between payload size, BER, and the optimal number of fragments for real-time adaptation. Finally, the analytical results are validated against independent MATLAB simulation results, showing a very close agreement in terms of access delay and fragmentation gain, which confirms the accuracy and practical relevance of the proposed model.</p>