A simulation design of LTE communication system under adaptive modulation schemes

The LTE standard uses three different modulation schemes to adapt to various channel conditions in order to improve achievable data rates. These modulation schemes are the QPSK, 16-QAM and 64-QAM. This paper presents an overview of a LTE digital communication system Simulink model, designed in order to study the effects of the QPSK, 16-QAM and 64-QAM modulation schemes on the BER performance with an AWGN channel model. Different subsystems within the transmitter and receiver blocks are implemented in Simulink. It is noted that the LTE system uses Turbo channel coding and bitlevel scrambling to offer reliable and secure services to the users. Depending on the assumed channel condition (clear, medium clear or noisy), the 64-QAM, 16-QAM or QPSK modulation scheme, on the transmitter side; as well as the corresponding demodulation scheme, on the receiver side; are automatically selected. Based on the recovered data bits, the obtained bit error rates are analyzed, compared and discussed.