Comparsion of M-Ary psk,fsk,qapsk.pptx

NA

1. ELL 727 ASSIGNMENT COMPARISON OF M-ARY PSK,FSK,QAPSK 1 Submitted By : Keshav (2022JOP2591) Satyander Singh (2022JOP2600) Submitted To: Prof. Vinod Chandra

2. Outline Abstract Introduction to M- ary PSK, QAPSK and FSK Comparison of M- Ary Modulation Schemes wrt Bandwidth Efficiency, Noise Performance and Implementation Complexity Summary References

3. Modulation 3   The process of varying one or more properties of a periodic  waveform with a modulating signal that typically contains information to be transmitted. modulate

4. Types of Modulation Amplitude M-ASK: Amplitude Shift Keying Frequency M-FSK: Frequency Shift Keying Phase M-PSK: Phase Shift Keying Amplitude + Phase M-QAM: Quadrature Amplitude Modulation s ( t ) = A cos ( 2π f c t + 𝜙 )

5. Introduction What is M- Ary Modulation? In a M array modulation two or more bits are grouped together to form a symbol and an assigned signal is transmitted during the symbol period Ts by changing one of the parameter of the carrier (Amplitude, Frequency or Phase). N umber of possible symbols given by M= T hen the symbol period is given by . If phase of the carrier is modulated it is known as MPSK. where m=0, 1, 2, ……., M-1 If frequency is modulated it is known as MFSK. where m=0, 1, 2, ……., M-1 Modulation of amplitude as well as phase is know as M QAPSK.  

6. 6 M-ary signaling scheme: In this signaling scheme 2 or more bits are grouped together to form a symbol. One of the M possible signals s 1 (t) ,s 2 (t),s 3 (t),……s M (t) is transmitted during each symbol period of duration T s . The number of possible signals = M = 2 n , where n is an integer.

7. 7 n M = 2 n Symbol 1 2 0, 1 2 4 00, 01, 10, 11 3 8 000, 001, 010,011,... 4 16 0000, 0001, 0010,0011,…. …. …… ………. The symbol values of M for a given value of n:

8. 8 M-ary Phase Shift Keying(MPSK) In M-ary PSK, the carrier phase takes on one of the M possible values, namely  i = 2 * (i - 1)  / M where i = 1, 2, 3, …..M. The modulated waveform can be expressed as where E s is energy per symbol = (log 2 M) E b T s is symbol period = (log 2 M) T b.

9. 9 The above equation in the Quadrature form is By choosing orthogonal basis signals defined over the interval 0  t  T s

10. 10 M- ary signal set can be expressed as Since there are only two basis signals, the constellation of M- ary PSK is two dimensional. The M- ary message points are equally spaced on a circle of radius E s , centered at the origin . The constellation diagram of an 8-ary PSK signal set is shown in fig.

11. 11 Fig: Constellation diagram of an M-ary PSK system(m=8)

12. M-PSK 12 I Q ‘10’ ‘01’ ‘11’ I Q ‘1’ ‘0’ I Q ‘111’ ‘100’ ‘010’ ‘011’ ‘001’ ‘000’ ‘100’ ‘101’ I Q ‘1111’ ‘0000’ BPSK QPSK 8-PSK 16-PSK

13. 13 Noise Immunity: Increasing M implies that the constellation is more densely packed, and hence the distance between the two points reduces, which leads to poor noise immunity. Bandwidth Efficiency: T he first null bandwidth of M- ary PSK signals decrease as M increases while R b is held constant. Therefore, as the value of M increases, the bandwidth efficiency also increases.

14. 14 M-ary Frequency Shift Keying(MFSK) In M-ary FSK modulation the transmitted signals are defined by: where f c = n c /2T s , for some fixed integer n. The M transmitted signals are of equal energy and equal duration, and the signal frequencies are separated by 1/2T s Hertz, making the signals orthogonal to one another.

15. 15 The channel bandwidth of a noncohorent MFSK is : This implies that the bandwidth efficiency of an M- ary FSK signal decreases with increasing M. Therefore, unlike M-PSK signals, M-FSK signals are bandwidth inefficient. However, Noise Immunity of M-FSK is better as compared to both M-PSK and M-QAPSK

16. 16 M-ary Quadrature Amplitude Modulation (QAM) It’s a Hybrid modulation As we allow the amplitude to also vary with the phase, a new modulation scheme called quadrature amplitude modulation (QAM) is obtained. The constellation diagram of 16-ary QAM consists of a square lattice of signal points.

17. Quadrature Amplitude Modulation Change both amplitude and phase s(t)= A cos ( 2π f c t + 𝜙 ) 64-QAM: 64 constellation points, each with 8 bits I Q ‘1000’ ‘1100’ ‘0100’ ‘0000’ ‘1001’ ‘1101’ ‘0101’ ‘0001’ ‘1011’ ‘1111’ ‘0111’ ‘0011’ ‘1010’ ‘1110’ ‘0110’ ‘0010’ Bits Symbols ‘1000’ s 1 =3a+3ai ’ 1001’ s 2 =3a+ai ‘1100’ s 3 =a+3ai ‘1101’ s 4 = a+ai a 3a 16-QAM

18. 18 Noise Immunity and Bandwidth : Noise Immunity of M- QAM is superior to M- ary PSK. Bandwidth efficiency of M-QAM is identical to M- ary PSK.

19. Comparison of decreases in case of MPSK and MQAPSK with increase of M. H ence, Noise Immunity also decreases . 2. Decrease in is more rapid in MPSK as compared to that of MQAPSK. in MFSK increases with increase in M and hence the Noise Immunity for M- ary FSK increases as M increases. 4. MFSK is most immune to noise or symbol probability error.   Theory Details Table.1

20. Comparison of Spectral Efficiency of Modulation Schemes M-PSK and QAPSK image shows the average particle size of ~ 180 nm .   M-FSK Theory Details From the above table we notice that in M ary PSK as the values of M increases the spectral efficiency also increases, a similar data is there in M ary QAPSK. In M ary FSK spectral efficiency is constant for M=2 and M=4 and after that it decreases continuously. Table.2

21. 21 MPSK Receiver and Transmitter

22. 22 MFSK Transmitter and Receiver

23. 23 MQAPSK Transmitter and Receiver

24. Implementation Complexity and Cost While assuming the complexity and cost same for transmitter of the three schemes we compared them only based on receiver complexity and cost. M Ary PSK In this scheme we require N square law device, 2 multiplier, 1 bandpass filter, 2 integrator, 1 analog to digital converter and 1 parallel to serial converter . M Ary FSK In this scheme for receiver we require M bandpass filter, M envelop detector, 1 decision device, 1 N bit analog to digital converter and 1 parallel to serial converter. M Ary QAPSK In this scheme we require 2 square law device, 2 multiplier, 1 bandpass filter, 2 integrator, 2 analog to digital converter and 1 parallel to serial converter. MODEL PRICES FOR COMPONENTS MUX/ Switch = Rs 10 Integrator= Rs 20 Multiplier= Rs 200 Bandpass filter= Rs 15

25. Decision device= Rs 20 Analog to digital converter= Rs 10 Parallel to Serial converter = Rs 5 (where N is the no. of bits per symbol) Envelop detector= Rs 15   Table.3 Implementation Complexity and Cost Thus, from above table we see that complexity of M- Ary PSK and FSK increases with increase in value of M whereas for QAPSK it remains same. Among PSK and FSK the latter shows rapid increase in complexity and hence becomes costly as M increase. Therefore, in terms of implementation QASK is best in terms of less complexity and cost. M Ary No. of Components Price (Rs)   M=4 M=8 M=16 M=32 M=64 M=4 M=8 M=16 M=32 M=64 PSK 9 10 11 12 13 475 680 885 1090 1295 FSK 11 19 35 67 131 170 290 520 1000 1960 QAPSK 10 10 10 10 10 885 890 895 900 905

26. SUMMARY Table.4 S.NO. Parameter MPSK MFSK QAPSK 1 Modulation Phase Frequency Quadrature amplitude and Phase 2 Location of Signal Points On circle On M signal axis Signal points are placed symmetrically about origin 3 Distance between signal points 4 Error probability Highest Least Less than MPSK but more than MFSK for high value of M 5 Noise immunity least Highest Better than MPSK 6 Bandwidth required Same as QAPSK Highest among three Same as MPSK 7 Complexity Shows increase but less rapid than MFSK Increases with M Remains almost same 8 Cost Increases with M but less rapid than MFSK Increases with M Least for high value of M S.NO. Parameter MPSK MFSK QAPSK 1 Modulation Phase Frequency Quadrature amplitude and Phase 2 Location of Signal Points On circle On M signal axis Signal points are placed symmetrically about origin 3 Distance between signal points 4 Error probability Highest Least Less than MPSK but more than MFSK for high value of M 5 Noise immunity least Highest Better than MPSK 6 Bandwidth required Same as QAPSK Highest among three Same as MPSK 7 Complexity Shows increase but less rapid than MFSK Increases with M Remains almost same 8 Cost Increases with M but less rapid than MFSK Increases with M Least for high value of M

27. References Principle of Communication Systems by Taub and Schilling. Channel Capacity Calculations For M– ary N-dimensional Signal sets Philip Edward McIllree , B.Eng. Communication Systems by S. Haykin . Modern Digital and Analog Communication Systems by B.P Lathi.