Packet size and modulation scheme can play an important role on optimizing the data rate of Long Term Evolution (LTE) system. The performance of the existing LTE system is evaluated in this paper in term of throughput and packet loss for Orthogonal Frequency-Division Multiple Access (OFDMA) modulation scheme with different packet sizes. The performance of LTE system for different packet size is done. The simulation experiments are done using Mat lab and Simulink libraries. The results show and discuss the effects of packet size and adaptation modulation on the performance of LTE based on throughput and packet loss. Moreover, the Signal-to-noise ratio (SNR) threshold values can be optimized in order to enhance the performance of LTE system. Experiments of packet loss illustrated that it is possible to get an accepted Packet Error Rate (PER) before reaching to SNR threshold values by enhancing an optimizing technique such as Markov Decision Process (MDP).