Bit error rate analysis and performance of OFDM system ... · transmission. Orthogonal frequency...
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Bit error rate analysis and performance of OFDM system using digital modulation techniques Neha Singh 1 , Mohd. Javed Khan 2 # Electronics communication engineering, Integral University luck now Abstract— Wireless communication is a standout amongst the most dynamic zone of innovation improvement within recent memory. Present day communication frameworks are intended to help various applications, for example, information, voice, video and sight and sound transmission, henceforth they require high information rate, phantom productivity and inter symbol interference (ISI) free transmission. Orthogonal frequency division multiplexing (OFDM) meets the above necessities however changes in Signal to Noise Ratio (SNR) is very normal because of varieties in envelope of OFDM flag which corrupts framework execution. Request of fast remote interchanges is expanding step by step. To satisfy this need OFDM (Orthogonal Frequency Division Multiplexing) is prominently utilized alongside different balance methods in fifth Generation versatile correspondences. In this paper the execution of QAM, QPSK, and BPSK broke down with differing estimation of FFT of OFDM. The investigations have been accomplished for SER (Symbol Error Rate) with Eb/N0 (SNR) utilizing MATLAB. Keywords— OFDM, signal noise ratio (SNR), QPSK, communication, Multiplexing, BPSK, QAM I. INTRODUCTION OFDM is transforming into the chosen modulation technique for wireless communication to reduce multipath fading effects and to provide massive data rates. OFDM is a multicarrier transmission system that uses the method of ripping smaller subcarriers of frequencies to agitate multipath drawback. The OFDM system is a twin of the Frequency Division multiplexing techniques. In advanced modulation, digital images are changed over into waveforms that are perfect with the qualities of the channel. Band pass modulation is a procedure by which the data flag is changed over to sinusoidal waveform for advanced adjustment. Coherent and non-coherent modulation/demodulation is the fundamental sorts of bandpass modulation. Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), and Quadrature Amplitude Modulation (QAM) are particular organizations of these methods. In a perfect channel the transmitted flag from the transmitter will go through channel upto the receiver, where it is demodulated to get an ideal portrayal of the original signal. Anyway in actuality they got signal comprises of blend of attenuated and reflected rendition of the transmitted signal. In addition to these, the channel adds different sorts of noise to the signal. This influences the bit error rate. Any constant correspondence framework contains noise. This noise results in some likelihood of mistake at the demodulator. Likewise as various communication systems have diverse sensitivities to blunders, there exists a distinctive approach to address them. Wireless communication systems arrive in an assortment of structures and will have diverse channel attributes while planning a correspondence framework. A portion of these incorporate Fading, Shadowing, Interference Propagation way misfortune etc. II. OFDM Orthogonal frequency division multiplexing is a extensively used modulation and multiplexing expertise, it becomes the key factor in telecommunications standards together with wireless LANs, DTT and radio distribution in to a large extent of the earth. In the point of reference time, as well as now, the OFDM is termed in the literature as Multi-carrier and Fourier Transform. OFDM is essentially transmitting lower rate data over multi carrier in order to send long sequence in parallel data stream with IFFT orthogonal concept. The carriers are prepared orthogonal to each other by suitably choosing the frequency separating among them. A multicarrier system, for example FDM or WDM divides the total available bandwidth in the spectrum into sub- bands for multiple carriers to send in parallel.(1) And, its multiplexed a large number of low data rate carriers to make a compound high data rate communication system. Orthogonality gives the carriers a suitable cause to be narrowly spaced with overlapping without inter carrier interference (ICI). In Frequency Division Multiplexing (FDM), the transmitted signal is part into a lot of individual signals, known as subcarriers which are in the frequency domain. At that point each subcarrier is modulated using a conventional modulation format, and later they are jointly combined to generate the FDM signal. Every one of the subcarriers in FDM transmission is independently recovered by the receiver. And, if the subcarrier signals accomplish the orthogonality condition then this result in overlapping of spectrum and hence spectral efficiency is improved and it is known as OFDM. Information with bit rate R is transmitted into N parallel channels, each one of them with separate frequencies. Over each channel, the total bit rate is spread in equal parts at rate R/N. In each channel the information will be mapped to represent an information symbol and then multiplied by its corresponding frequency. These parallel information symbols are summed to form one OFDM symbol. Thus the duration of each OFDM symbol is Ts=N/R. JASC: Journal of Applied Science and Computations Volume VI, Issue V, May/2019 ISSN NO: 1076-5131 Page No:2702
Transcript of Bit error rate analysis and performance of OFDM system ... · transmission. Orthogonal frequency...
Bit error rate analysis and performance of OFDM
system using digital modulation techniques Neha Singh
1, Mohd. Javed Khan
2
#Electronics communication engineering, Integral University luck now
Abstract— Wireless communication is a standout amongst the most dynamic zone of innovation improvement within recent memory.
Present day communication frameworks are intended to help various applications, for example, information, voice, video and sight and
sound transmission, henceforth they require high information rate, phantom productivity and inter symbol interference (ISI) free
transmission. Orthogonal frequency division multiplexing (OFDM) meets the above necessities however changes in Signal to Noise Ratio
(SNR) is very normal because of varieties in envelope of OFDM flag which corrupts framework execution. Request of fast remote
interchanges is expanding step by step. To satisfy this need OFDM (Orthogonal Frequency Division Multiplexing) is prominently utilized
alongside different balance methods in fifth Generation versatile correspondences. In this paper the execution of QAM, QPSK, and BPSK
broke down with differing estimation of FFT of OFDM. The investigations have been accomplished for SER (Symbol Error Rate) with
Eb/N0 (SNR) utilizing MATLAB.
Keywords— OFDM, signal noise ratio (SNR), QPSK, communication, Multiplexing, BPSK, QAM
I. INTRODUCTION
OFDM is transforming into the chosen modulation technique for wireless communication to reduce multipath fading effects and to provide massive data rates. OFDM is a multicarrier transmission system that uses the method of ripping smaller subcarriers of frequencies to agitate multipath drawback. The OFDM system is a twin of the Frequency Division multiplexing techniques. In advanced modulation, digital images are changed over into waveforms that are perfect with the qualities of the channel. Band pass modulation is a procedure by which the data flag is changed over to sinusoidal waveform for advanced adjustment. Coherent and non-coherent modulation/demodulation is the fundamental sorts of bandpass modulation. Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), and Quadrature Amplitude Modulation (QAM) are particular organizations of these methods. In a perfect channel the transmitted flag from the transmitter will go through channel upto the receiver, where it is demodulated to get an ideal portrayal of the original signal. Anyway in actuality they got signal comprises of blend of attenuated and reflected rendition of the transmitted signal. In addition to these, the channel adds different sorts of noise to the signal. This influences the bit error rate. Any constant correspondence framework contains noise. This noise results in some likelihood of mistake at the demodulator. Likewise as various communication systems have diverse sensitivities to blunders, there exists a distinctive approach to address them. Wireless communication systems arrive in an assortment of structures and will have diverse channel attributes while planning a correspondence framework. A portion of these incorporate Fading, Shadowing, Interference Propagation way misfortune etc.
II. OFDM
Orthogonal frequency division multiplexing is a extensively used modulation and multiplexing expertise, it becomes the key factor in telecommunications standards together with wireless LANs, DTT and radio distribution in to a large extent of the earth. In the point of reference time, as well as now, the OFDM is termed in the literature as Multi-carrier and Fourier Transform. OFDM is essentially transmitting lower rate data over multi carrier in order to send long sequence in parallel data stream with IFFT orthogonal concept. The carriers are prepared orthogonal to each other by suitably choosing the frequency separating among them. A multicarrier system, for example FDM or WDM divides the total available bandwidth in the spectrum into sub-bands for multiple carriers to send in parallel.(1) And, its multiplexed a large number of low data rate carriers to make a compound high data rate communication system. Orthogonality gives the carriers a suitable cause to be narrowly spaced with overlapping without inter carrier interference (ICI). In Frequency Division Multiplexing (FDM), the transmitted signal is part into a lot of individual signals, known as subcarriers which are in the frequency domain. At that point each subcarrier is modulated using a conventional modulation format, and later they are jointly combined to generate the FDM signal. Every one of the subcarriers in FDM transmission is independently recovered by the receiver. And, if the subcarrier signals accomplish the orthogonality condition then this result in overlapping of spectrum and hence spectral efficiency is improved and it is known as OFDM. Information with bit rate R is transmitted into N parallel channels, each one of them with separate frequencies. Over each channel, the total bit rate is spread in equal parts at rate R/N. In each channel the information will be mapped to represent an information symbol and then multiplied by its corresponding frequency. These parallel information symbols are summed to form one OFDM symbol. Thus the duration of each OFDM symbol is Ts=N/R.
JASC: Journal of Applied Science and Computations
Volume VI, Issue V, May/2019
ISSN NO: 1076-5131
Page No:2702
TABLE I .Main parameter of the OFDM
Modulation BPSK,QPSK,16-QAM,64-QAM
Number of subcarriers 52 OFDM symbol duration 4µs
Noise channel AWGN,Rayleing,Rician Data rate 6,9,12,18,24,36 Code rate ½, 2/3,3/4
Channel spacing 20MHz Protect interval 800ns Channel spacing 20MHz
III. DIGITAL MODULATION SCHEMES
A digital signal can modulate amplitude, frequency, or period of sinusoidal carrier wave. If the modulating waveform consists of NRZ rectangular pulses, then the modulated parameter will be switched or keyed from one discrete value to another(4). These outcomes into three basic types of digital modulation schemes namely Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), and Phase Shift Keying (PSK).
A. Phase shift keying
The phase shift of a sinusoidal carrier is changed from one value to the other value corresponding to the change over from 0 to 1 or from 1 to 0 in the digital information. The error probability is very low and noise immunity is high. This paper manages the types of PSK viz BPSK, QPSK and QAM. This segment will portray these techniques in detail. 1. BPSK: In Binary phase shift keying (BPSK), the carrier gets 00 or 1800 phase shift corresponding to two different voltage
levels of binary modulating signal. If the sinusoid is of amplitude A, it has a power ps=1/2 A2 so that A = (2PS)1/2. The
transmitted signal is given by
VBPS(t) = b(t)(2Ps)cosw0t (1)
Ps = ½ erfc (Eb/No) (2)
Where b(t) is a stream of binary digits with voltage levels
Figure1-Phase modulation of binary signal on the carrier wave with BPSK(4)
Figure 2 –constellation diagram of BPSK(4)
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2. QPSK: In Quadrature phase shift keying (QPSK), when a data is transmitted using BPSK technique the channel bandwidth
required is 2fb and the QPSK method reduces that data transmission to fb, it is known as multilevel phase modulation. In
this two progressive bits in a bit stream are joined together to shape a message and each message is represented by distinct
value of phase shift of a carrier. The QPSK signal is spoken as, since there are 4 phases it is called as 4-PSK or Quadrature
PSK systems.
VQPSK(t)=(2Ps)1/2cos[wot+(2m+1)π/4]...............m=0,1,2,3 (3)
Ps = erfc(Eb/No) (4)
Figure3-Phase modulation of binary signal on the carrier wave with QPSK (6)
Figure 4 –constellation diagram of QPSK(6)
3. QAM: Quadrature Amplitude Modulation (QAM) improves the noise immunity of the system by allowing the signal vectors to differ, not only in their phase but also in amplitudes. And, it utilizes carrier phase shifting and synchronous detection to permit two DSB signals to occupy the same frequency band. The two DSB signals are orthogonal to one another.
Ps = 2 (1-1/ )1/2 erfc(Eb/No) (5)
Figure5-Phase modulation of binary signal on the carrier wave with QAM(6)
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Figure6-constellation diagram of 16-QAM (6)
IV PERFORMANCE PARAMETERS 1. BIT ERROR RATE (BER): Bit error gives the quantity of bits in error per unit time. In advanced communication, the quantity of bits in mistake are the quantity of bits received in an information stream over a correspondence channel that are adjusted either because of noise, interference, distortion or bit synchronization, attenuation, wireless multipath fading etc(1). Bit error probability Pe is characterized as the expectation value of the bit error ratio for example the number of bit errors divided by the total number of transferred bit during a defined time interval. It is desirable to improve by picking strong signal strength and by picking a robust modulation technique. In a loud channel the BER may be expressed as a function of signal to noise ratio denoted as Eb/No and is given by BER = ½ erfc(Eb/No). 2. AWGN: In communication theory, usually accepted that the transmitted signals are distorted by some noise. The most widely recognized noise to accept is additive Gaussian noise i.e. the so called additive white Gaussian noise channel AWGN. The detection process of a channel with AWGN is that the noise affects each transmitted symbol freely and such a channel is called memory less channel. The term additive means that the noise is just superimposed or added to signal that there are no multiplicative systems at work. This channel is linear and time-invariant and its frequency reaction is level for every one of the frequencies. 3. SNR signal noise ratio: SNR is a contrast between the signal strength a system replicates and contrasted to the signal
strength or amplitude of its background noise. SNR incorporates the noise the noise in the environment and undesirable signal.
SNR = 10log10 (Signal Power/ Noise Power) db (6) 4. Rayleigh fading channel: Rayleigh fading channel: Rayleigh fading is a statistical model for the impact of a propagation environment on a radio signal, for example that used by wireless devices and Rayleigh fading model acknowledge that the magnitude of a signal that has gone through, such a transmission medium (additionally called a communications channel) will vary randomly, or fade, as indicated by a Rayleigh distribution the radial component of the sum of two uncorrelated Gaussian random factors. Rayleigh fading is viewed as a reasonable model for tropospheric and ionospheric signal propagation just as the effect of heavily built-up urban conditions on radio signals. Rayleigh fading is most appropriate when there is no dominant propagation along a viewable pathway between the transmitter and receiver.
V.SIMULATION RESULTS
FIGURE 7: BER Performance of BPSK AWGN channel using MATLAB code
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In this paper matlab is used to simulate the performance of the digital modulation scheme BPSK, QPSK and QAM their performance is evaluated by find SNR and BER over AWGN.
Fig7. Above shows BER versus SNR (Eb/No in dB) execution examination of BPSK modulation techniques over
Additive White Gaussian Noise (AWGN) channels utilizing MATLAB code.
SNR(DB) BER (using BPSK)
0 0.0757
1 0.0566
2 0.0389
3 0.0215
4 0.0118
5 0.0058
6 0.0021
7 8.3X10-4
8 2.5X10-4
9 1.3X10-4
10 0
Table 2 BER results for OFDM model using BPSK modulation
FIGURE 8: BER Performance of QAM AWGN channel using MATLAB code
Fig8. Above shows BER versus SNR (Eb/No in dB) execution examination of QAM modulation techniques over Additive White Gaussian Noise (AWGN) channels utilizing MATLAB code.
SNR(dB) BER(using QAM)
0 0.1365
1 0.1157
2 0.0966
3 0.0758
4 0.0573
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5 0.0403
6 0.0277
7 0.0181
8 0.0093
9 0.0039
10 0.0017
Table 3. BER results for OFDM model using QAM modulation
has gone through, such a transmission medium (additionally called a communications channel) will vary randomly, or fade, as indicated by a Rayleigh distribution the radial component of the sum of two uncorrelated Gaussian random factors.(3). Rayleigh fading is viewed as a reasonable model for tropospheric and ionospheric signal propagation just as the effect of heavily built-up urban conditions on radio signals. Rayleigh fading is most appropriate when there is no dominant propagation along a viewable pathway between the transmitter and receiver.
FIGURE 9: BER Performance of QPSK AWGN channel using MATLAB code (8)
Fig9. Above shows BER versus SNR (Eb/No in dB) execution examination of QPSK modulation techniques over Additive White Gaussian Noise (AWGN) channels utilizing MATLAB code (9).
SNR(dB) BER(using QPSK) 0 0.2088 1 0.1803 2 0.1475 3 0.1125 4 0.0807 5 0.0554 6 0.0313 7 0.0172 8 0.0090 9 0.0036 10 0.0015
Table 4. BER results for OFDM model using QPSK modulation
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Figure 10: BER plot for BPSK, QAM and QPSK in AWGN channel (5)
Figure11: BER plot for BPSK, QAM and QPSK in RAYLEIGH channel (5)
It shows BER versus SNR (Eb/No in dB) performance analysis of BPSK, QPSK & QAM modulation techniques over Additive White Gaussian Noise channel using MATLAB code. And it is clear that BPSK has lower BER than QPSK & QAM i. For example at Eb/No of 4dB, BER in BPSK is around 0.01 whereas QPSK and QAM is around 0.1. At SNR= 10 BER for BPSK is 0 but for QPSK and QAM it is greater than 10-3. If we compare BER among QPSK and QAM then at SNR 10, BER for QPSK is approximately 10-3 where as QAM it is around 10-1(10).Therefore QPSK performs better than QAM. Also at SNR=14, BER for QPSK is 0 where as for QAM it is approximately 10. RESULT
In this paper assessed the BER execution of OFDM with the assistance of matlab apparatus and the execution of OFDM system was tried for three digital modulation techniques to be specific BPSK, QPSK and QAM. The simulation result it is seen that the BPSK enables the BER to be improved in a noisy channel at the cost of maximum data transmission capacity. It is concluded that BPSK performs better compared to the QPSK and QAM for both the cases using AWGN channel and Rayleigh fading channel. And QAM with higher mode value gives best spectral efficiency and under worst conditions and it also use QPSK, BPSK.
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6. (3)Performance Analysis of Different QAM Techniques Using Rician Fading Channel Prerna Amlavad | Mukesh
Ptidar, 2018 7. (5)J. Lowery et al., “Performance of Orthogonal-frequency-division multiplexing in ultra long-haul WDM systems,”
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