Exploiting the Adaptive Modulation Scheme to Increase the Throughput Performance of 3GPPLTE Downlink Interface Air

The driver for the choice of alternating use of modulation scheme is to increase the data rates where there is enough signal power to transmit it and improve the overall throughput performance. The adaptive modulation is a bit loading scheme exploited to increase the throughput performance of a communication link. This scheme will take into account the varying SNR values across the N subcarriers and instantaneous channel quality, and adapt a modulation scheme to the subcarrier based on the target performance level. Thus, more bits can be transmitted over a subcarrier while achieving the desired performance level. The modulation mode is picked from modulation schemes standardised for 3GPP LTE downlink-QPSK, 16QAM, 64QAM, and consideration is also given to BPSK and 8PSK schemes. A target performance threshold is adopted for each modulation mode in a subcarrier viewing it as AWGN subchannel. The average throughput obtained from the simulation with the constraint of the PC is 86.895 Mbps.