A R DIGITECH International Journal Of Engineering, Education And Technology (ARDIJEET) www.ardigitech.in ISSN 2320-883X,VOLUME 3 ISSUE 2 ,01/04/2015 System Generator Based Implementation of QAM and Its Variants Nilesh Katekar *1, Prof. G. R. Rahate*2 *1 Student of M.E. VLSI & Embedded system, PCCOE Pune, Pune University, India *2 Astt. Prof. in Electronics and Telecommunication department, PCCOE Pune, Pune University, India *1 nileshkatekar05@gmail.com , *2 ganesh.rahate@pccoepune.org Abstract: Quadrature amplitude modulation (QAM) is widely used modulation technique in today’s wireless communication system. As it support the high data rate transmission and it efficiently uses the power and bandwidth resources. In this paper, basic QAM and its two variants are implemented in Xilinx system generator and output is observed and analyzed Keywords: QAM, BER, system generator I Introduction QAM is combinations of two modulation technique ASK and PSK, as it gives the variation in both amplitude and phase at the output. QAM has the ability to transmit the high data rate due to that it is widely used modulation technique in wireless technologies like 3G, Wi-Fi, Wi-MAX etc. However, it must also be noted that when using modulation technique such as 64 QAM, better signal-to-noise ratios (SNRs) are needed to overcome any interference and maintain a certain bit error ratio (BER) [1] Use of different QAM variants at different time is depends on the channel condition. When channel condition is good or user equipment is near to the transmission station then higher order modulation is preferred such as 64 QAM, and when channel condition is poorer then lower order modulation technique has to be switched such that 64 QAM to 16 QAM or 8 QAM as per the required BER. This is adaptive modulation technique used in today’s wireless technology. II Related Work Reference [4] is a text book; it explores the basics of QAM and modulation techniques with help of diagrams, waveforms and mathematical equations. In reference [2] author has implemented the simulink based QAM system using the direct simulink block sets and plotted the result on error rate versus SNR(db). In reference [7], author’s implemented16 QAM modulation and demodulation in MATLAB, calculated results for different BER for different SNR values and compare the 16 QAM BER results with BPSK and QPSK modulations and concluded that performance of 16 QAM modulations is superior to BPSK and QPSK modulation. In reference [8], authors implemented the 16 QAM transmitter and receiver on FPGA. In this paper authors design 16 QAM modulator and demodulator in MATLAB system generator and obtain the results on FPGA board. In paper [1] author implemented QAM modems on FPGA using partial reconfiguration and as per the user requirement, user can switch between different modulations and demodulations technique in runtime by configuring control register in FPGA, switching between different modulations manually. Here authors of this paper are trying to make system adaptive by passing different channel conditions and a partial work in this direction is presented in this paper. III Basics of QAM Among all the forms of digital modulation used in communication system QAM is different. In this system, digital signal to be transmitted is acts both on amplitude and as on the phase of the carrier signal. Therefore, QAM modulation is a mix of ASK with PSK[4] Fig 1: Construction of QAM [3]