Comparison of BER performances of 64-PSK and 64-QAM in AWGN channels
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Comparison of BER performances of 64-PSK and 64-QAM in AWGN channels
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Comparison of BER performances of 64-PSK and 64-QAM in AWGN channels
- 1. COMPARISON OF BER PERFORMANCES OF 64-PSK AND 64-QAM IN AWGN CHANNELS EE451 Communication Systems II Berk SOYSAL Yiğitcan AYDOĞMUŞ
- 2. OUTLINE 1 INTRODUCTION 2 BINARY MODULATION 3 M-ARY MODULATION 4 M-PSK MODULATION 5 M-QAM MODULATION 6 AWGN CHANNEL EFFECT 7 BIT ERROR RATE 8 RESULTS 9 CONCLUSION
- 3. INTRODUCTION • What is digital communication ? • Digital communication is the transmission of information that has been encoded digitally, and passed through digital devices such as computers.
- 4. INTRODUCTION • What is modulation ? • Modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal with an information bearing signal. • Why do we need modulation ? • Low frequency signals are more immune to noise. • Prevent interference. • Reduce the antenna size in designed transceivers.
- 6. M-ARY MODULATION • In general, M-ary communication is used when one needs to design a communication system that is bandwidth efficient. • However, the gain in bandwidth is accomplished at the expense of error performance.
- 7. M-ARY MODULATION • To use M-ary modulation, the bit stream is blocked into groups of λ bits. • The number of bit patterns is M = 2λ • The symbol transmission rate is; Rs = 1/Ts = 1/(λTb) = Rb/λ symbols/sec There is a bandwidth saving of 1/λ compared to binary modulation.
- 8. M-PSK MODULATION • In this modulation type, the information is encoded in the phase of the transmitted signal.
- 9. M-PSK MODULATION • The signals lie on a circle of radius √Es, and are spaced every 2π/M radians around the circle. Constellation Diagram of 64-PSK; Decision Regions for M-PSK receiver;
- 10. M-QAM MODULATION • In this modulation type, the information is encoded in both the amplitude and the phase of the transmitted signal. • In QAM the transmitted signal has the form:• This signal is demodulated by multiplying with a cosine signal;• Or equivalently; • Applying LPF removes the sine and cosine terms and leaves only the message term.
- 11. 64-QAM MODULATION • In 64 QAM there are 64 signal points in the constellation that are equally divided into four quadrants. • Since the constellation is divided equally into four quadrants, normalizing the energy in a single quadrant will simplify things. Constellation Diagram of 64-QAM; Calculating the total energy in any one of the quadrant; The average energy is and the normalization factor will be .
- 12. AWGN CHANNEL EFFECT Additive white Gaussian noise (AWGN) is a channel model in which the only impairment to communication is a linear addition of wideband or white noise with a constant spectral density and a Gaussian distribution of amplitude. Noisy Constellation Diagrams;
- 13. BIT ERROR RATE • The bit error rate or bit error ratio (BER) is the number of bit errors divided by the total number of transferred bits during a studied time interval. • Bit error rate (BER) is a parameter which gives an excellent indication of the performance of a data link.
- 14. THEORETHICAL BER OF M-QAM & M-PSK k=log2M
- 15. THEORETHICAL BER GRAPH OF M- PSK
- 16. THEORETHICAL BER GRAPH OF M- QAM
- 17. RESULTS
- 18. M-PSK VERSUS M-QAM Bandwidth and Power Efficiency of M-PSK Signals Bandwidth and Power Efficiency of M-QAM Signals
- 19. SHANNON’S LIMIT
- 20. THANK YOU FOR LISTENING !