Design and implementation of adaptive modulation modem based on software defined radio (sdr)‎ for wimax system

Abstract EN

This paper presents design and implementation of adaptive modulation modem for WiMAX system.

(BPSK, QPSK, 8QAM, 16QAM, 32QAM and 64QAM) are used in this work.

Software Defined Radio (SDR) is used for implementing this modem.

This work examines the benefits of using adaptive modulation in terms of probability of bit error and spectral efficiency.

It specifically examines the performance enhancement made possible by using linear prediction along with channel estimation in conjunction with adaptive modulation.

Simulation results proved that the adaptive system performance with estimator and predictor is better than other modulation alone.

The simulation results for adaptive modulation in compared to each modulation technique alone show that for BER = 10-3 with (fd=50Hz -200Hz) system the improvement occurs by decreasing S / N by 2- 3 dB.

As for BER = 10-4 with same Doppler frequency, the system improvement takes place by decreasing S/N by 1.3dB- 4dB.

Regarding BER = 10-5 with same Doppler frequency, the improvement is by decreasing S/N by 1.5dB-5 dB.

Simulation results also show the flexibility of the adaptive system to operate with different level of modulation based on switching of S / N.

Matlab 7.8 (R2009a) used for simulation of adaptive modulation system with AWGN and fading channel.