Most cellular standards for the forthcoming beyond 3G (B3G) and 4G technologies state Orthogonal Frequency-Division Multiple Access (OFDMA) for multiplexing and modulation procedures. OFDMA is able to combine multiple access techniques with Adaptive Quadrature Amplitude Modulation (AQAM) to maximize system performance while keeping the errors below a certain target. In order to achieve this objective, Channel Quality Indicators (CQI) are fedback from the receivers. However, potential errors and/or delays in the reception of such CQIs as well as an imperfect channel estimation may lead to a system performance degradation. This paper analyzes the impact of an imperfect adaptation on a Long Term Evolution (LTE) cellular network.