1. Performance Evaluation of Different QAM
Techniques Using Matlab/Simulink
Submitted by
VENKATARAJ R
Under the Guidance of
D. VIJAYALAKSHMI
Assistant Professor
Department of Electronics & Communications Engineering

2. Brief Overview
 Compares different Quadrature Amplitude Modulation (QAM)
techniques at different bit rates (8,16, 32, 64 and 256) based
on the Bit Error Rate (BER) versus the Ratio of Bit Energy to
Noise Power Spectral Density (Eb/No).
 Comparison between the resulting transmission errors in the
received signal at different noise or Eb/No levels.
 Model simulates the impact of changing the power of the
applied noise (AWGN) during the transmission process.

3. Bit error rate, BER is applicable to radio data links as
well as fiber optic data systems, Ethernet.
Any system that transmits data over a network of
some form where noise, interference, and phase
jitter may cause degradation of the digital signal.
AWGN is commonly used to simulate background
noise of the channel under study.

4. General QAM modulation/demodulation
Simulink model

6. Table 1: Parameter Setting for Random Integer

7. Table 2: Parameter Setting for General QAM Modulator/Demodulator
is the data symbol chosen from a I × J rectangular QAM constellation.
2d is the Euclidean distance between two adjacent
signal points

8. • 8-QAM: (I=4*J=2)
 [-2.13-.71i -2.13+.71i -.71-.71i -.71+.71i 2.13-.71i 2.13+.71i .71-.71i
.71+.71i]
• 16-QAM: (I=4*J=4)
 [-1.89-1.89i -1.89-.63i -1.89+.63i -1.89+1.89i -.63-1.89i -.63-.63i -.63+.63i .63+1.89i 1.89-1.89i 1.89-.63i 1.89+.63i 1.89+1.89i .63-1.89i .63-.63i
.63+.63i .63+1.89i]
• 32-QAM: (I=8*J=4)
 [-3.08-1.32i -3.08-.44i -3.08+.44i -3.08+1.32i -2.2-1.32i -2.2-.44i -2.2+.44i 2.2+1.32i -1.32-1.32i -1.32-.44i -1.32+.44i -1.32+1.32i -.44-1.32i -.44-.44i .44+.44i -.44+1.32i 3.08-1.32i 3.08-.44i 3.08+.44i 3.08+1.32i 2.2-1.32i 2.2.44i 2.2+.44i 2.2+1.32i 1.32-1.32i 1.32-.44i 1.32+.44i 1.32+1.32i .44-1.32i
.44-.44i .44+.44i .44+1.32i ]

9. Table 3: Parameter Setting for AWGN Channel
Table 4: Parameter Setting for Error Rate Calculation

10. Table 4: Parameter Setting for Error Rate Calculation

11. Table 5: To workspace Block

12. The main interface of the BERTool

13. Plots of the BER of the Simulated QAM techniques

14. Plots of the BER of the Simulated 8-QAM at different levels
of the noise power spectral density (Eb/No)

15. Plots of the BER of the Simulated 8-QAM at different levels of the input
signal power

16. Conclusion
• It demonstrates the utilization of the BERTool in
evaluating and comparing the performance of the
different QAM techniques.
• Discusses the proportional relation between the power
of the input signal and the noise variance implemented
by the added white Gaussian noise component.
• It provides a way to simulate the performance of these
communication techniques along with using the BERTool
in performing the evaluation phase in this model.

17. [1] Sam, W. Ho, "Adaptive modulation (QPSK, QAM), "
www.intel.com/netcomms/technologies/wimax/30
3788.pdf, December 30, 2007.
[2] Xiaolong Li, “Simulink-based Simulation of Quadrature
Amplitude Modulation (QAM) System”, Proceedings of The
2008 IAJC-IJME International Conference.
[3] “Exact BER Analysis of an Arbitrary Square/ Rectangular
QAM for MRC Diversity with ICE in Non-identical Rayleigh
Fading Channels” (2005 IEEE) by Laleh Najafizadeh, Chintha
Tellambura.

18. Thank you