Comparative Simulation & Analysis of 2- PSK Spreading Transceiver

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Comparative Simulation & Analysis of

2-PSK Spreading Transceiver

Pramod Kumar

Astt. Professor, Electronics Engineering Department, U.N.S.I.E.T.V.B.S. P.U. Jaunpur, Uttar Pradesh, India

pkrajdan@yahoo.com

Sudhir Singh

Astt. Professor, Electronics Engineering Department, U.N.S.I.E.T.V.B.S. P.U. Jaunpur, Uttar Pradesh, India

sukam02.sullko@gmail.com

Nagendra Kr. Gautam

Student, Of B.Tech, Electronics & Communication Engineering Department, U.N.S.I.E.T.V.B.S. P.U. Jaunpur, Uttar Pradesh, India

nkgautam.12@gmail.com

Abstract:

Wireless communication technology has taken on a prominent position in indoor environment applications recently, therefore direct sequence spread spectrum (DSSS) is proposed in addition to binary phase shift keying (BPSK), which not only have anti-jamming capability, concealment and low SNR but also provide efficient utilization of bandwidth and power, than the other communication system. The transmission environment in which DSSS yield desirable performance is based on Lab VIEW 8.5 and named as BPSK-Spreading transceiver. At the transmitter, the NRZ data stream is first mapped into BPSK symbols and then spread-out using different PN code like Hadamard code, Gold or Kasami sequences. The receiver first performs de-spreading and finally BPSK de-symbol mapping. We further focus on the applications of this technique to anti-jamming navigation broadcast, bootstrapping of spread spectrum communication as CDMA.

Keywords: MATLAB 7.8 Simulink, Lab VIEW 8.5, etc.

1. Introduction:

Communication technology has advent of personal communication system (PCS), which usually co-exist in the 2.4GHz ISM band. Therefore, the interference rejection property has become very important in developing a reliable wireless transmission system for indoor applications. A major issue of concern with digital communication has been that of providing for the efficient utilization of bandwidth and power. The justification for preoccupation with this issue is simply the fact that bandwidth and power are the two primary communication resources and it is therefore essential that they are used with care in the design of most communication systems. Nevertheless, wireless communication technologies for un-licensed band application are the situations where it is necessary to sacrifice the efficient utilization of these two resources in order to meet certain other design objectives i.e. ability to reject the interference whether among the various signal. This requirement is catered to by a class of signaling techniques known collectively as spread-spectrum modulation. The anti-jamming capability, associated with spread spectrum makes this technology suitable for un-licensed band applications. The wireless transmission environment in which DSSS yield desirable performance is based on Lab VIEW. The spread spectrum transmitter first perform the BPSK symbol mapping using sinusoidal carrier and then spread the spectrum using Hadamard code, Gold or Kasami sequences. Spreading consists of multiplying the input data by a pseudo-random or pseudo-noise (PN) sequence, the bit rate of which is much higher than the data bit rate.

2. Objective of this paper:

The present work has been undertaken with the following objectives:

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3. BPSK symbol mapping and spreading:

The first stage consists of a product modulator or multiplier with data sequence and carrier signal to perform BPSK modulation. The second stage consists of a PN sequence spreading. The phase modulation of has two values, 0 and , depending on the polarities of the data sequence at time t in accordance with the truth table of table 1

S.No. Input digital signal Bipolar NRZ signal BPSK output signal

1. Binary 0 _√ _cos

2. Binary 1 _√ _cos

In a coherent binary PSK system, the pair of signals, and used to represent binary symbols 1 and 0 respectively, are defined by

cos

cos cos

Where , and is the transmitted signal energy per bit, and carrier frequency is chosen to ⁄ for some fixed integer .

In BPSK the is a stream of binary digits with voltage levels which, as a matter of convenience we take to be at +1V and -1V. When = 1V we say it is at logic level 1 and when = -1V we say it is at logic level 0. Hence BPSK is given by bipolar NRZ level as

cos

For the second stage modulation i.e. spreading is performed by applying information bearing signal and

pseudo noise (PN) sequences to product modulator. Thus if is narrowband and the PN sequence is wideband, the product signal will have a spectrum that is nearly the same as the PN sequence, i.e. in context of our present application, the PN sequence perform the role of a spreading code. We may thus express the transmitted signal as

4. De-spreading & BPSK symbol de-mapping:

Accordingly, the channel output is given by

Where the binary PSK is signal, and is the PN sequence. In the receiver, the received signal is first multiplied by the PN sequence yielding an output that equals the coherent detector input .

In the above equation, we have noted that, by design, the PN sequence c(t) satisfies it’s property, that reproduced hear for convenience:

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5. Results and Discussion:

The direct sequence spread spectrum based PSK spreading transceiver system is analyzed for their anti-jamming capability, low SNR. Except first simulation all subsequent simulation demonstrated to the performance of PSK spreading transceiver system. The first simulation demonstrated that the PSK spreading transmitted system is correctness. The power spectral density (PSD) for input and output signal show that the model that the theoretical model is conformed. Results show the help of Lab VIEW/ MATLAB with-spreading better performance.

5.1 With Spreading:

0 0.02 0.04 0.06 0.08 0.1 0.12

0 2 4 6 8 10 12

B

E R

SNR (dB)

[1]. BER vs SNR(dB) for Length of Hadamrd code=60, No. user = 1

0 0.02 0.04 0.06 0.08 0.1 0.12

0 2 4 6 8 10 12

B E

R

SNR (dB)

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5.2 Without Spreading: 0

0.02 0.04 0.06 0.08 0.1 0.12

0 2 4 6 8 10 12

B

E R

SNR (dB)

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

0 2 4 6 8 10 12

B

E R

SNR (dB)

[1]. BER vs SNR(dB) for No. user = 1

BER vs SNR (dB) for No. of user=1: Without Spreading, Input power, refernceced to 1 ohm (watts):1

0 0.05 0.1 0.15 0.2 0.25 0.3

0 2 4 6 8 10 12

B E

R

SNR (dB)

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6. Conclusion:

Form the above observations and the simulation result we can say that, the spreading based 2-PSK transceiver is not only have the anti-jamming capability, low SNR value and concealments but also provided efficient utilization of bandwidth and power. More importantly, the technique Direct Sequence Spread Spectrum (DSSS),

is exceed the other communication system BER performance and have robustness against channel estimation errors. Its low SNR value properties has been designed provide the quality performance, because of low transmitting power is required, which increases the efficiency of the overall system. In summary, the main advantages of proposed technique i.e. high concealments, anti-jamming capability and low SNR property, provided that, any unauthorized receiver can’t detect the information, only the user detected it who is authorized for it, increased the channel capacity and required low transmitting power. In Short we can say that the technique Direct Sequence Spread Spectrum (DSSS) is attain more robust performance, and outperformed then the other digital communication system, it can conserved both power and bandwidth i.e. the primary sources of any communication system.

6.1 Suggestion for Future work:

Based on gathered observations while completing this project; topics were identified which would benefit for further investigation.

1. The spreading technique is analyzed for its processing gain, because it characterized this technique. 2. This technique is also analyzed for multipath propagations using both considering fading phenomena

and without considering fading phenomena, no of path will also very as pre requirements.

3. This technique is also be used for coding and spreading of the CDMA, to show its practical approaches.

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[4] Simon Haykin [2005]. “Digital Communications”. John Wiley and Sons: New York.

[5] Herbert Taub, Donald L Schilling [2008]. “Principals of communication system”. McGraw-Hill: New York. [6] Behrouz A. Forouzon [2006]. “Data Communications and Networking”. McGraw-Hill: New York.

[7] Robert H. Bishop, the University of Texas [2008]. “Lab VIWE 8.5 Student Edition”. National Instrumens. [8] T. S. Rappaport [2006]. “Wireless Communications Principles and Practice”. Pearson second Edition. [9] Simon Haykin [2005]. “Wireless Communications”. Wiley Student Edition: New York.

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[11] Juinn-Horng Deng [2011]. “A low-complexity MSK-based M-ary cyclic-shift keying transceiver for direct sequence spread spectrum system over multipath fading channels”. Wiley Online Library, DOI: 10.1002/dac.1237

0.338 0.34 0.342 0.344 0.346 0.348 0.35 0.352 0.354

0 2 4 6 8 10 12

B

E R

SNR (dB)