A SURVEY ON OPTIMIZATION BASED SPECTRUM SENSING TECHNIQUES TO REDUCE ISI AND PAPR IN OFDM BASED COGNITIVE RADIO SYSTEM

International Journal of Network Security & Its Applications (IJNSA) Vol. 11, No.1, January 2019
DOI: 10.5121/ijnsa.2019.11105 53
A SURVEY ON OPTIMIZATION BASED SPECTRUM
SENSING TECHNIQUES TO REDUCE ISI AND PAPR
IN OFDM BASED COGNITIVE RADIO SYSTEM
1
Mr.B.Maheswara Rao, 2
Dr.S.Baskar
1
Research scholar,2
Professor, Department of EEE,
Vel Tech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology
maheswar414@gmail.com, drbaskar@veltechuniv.edu.in,
ABSTRACT
Cognitive radio is emerging technologies in OFDM based wireless systems which are very important for
spectrum sensing. By using cognitive radio (CR) high data can be transferred with low bit error rate. The
key idea of OFDM is to split the total transmission bandwidth into the subcarriers which further reduce the
intersymbol interference (ISI) and peak to average power ratio(PAPR) in the signal. There are many
optimization based spectrum sensing techniques are existing for efficient sensing purpose but each has its
own advantages and disadvantages. This leads to start the comprehensive study for reducing PAPR and
ISI(Intersymbol interference) in terms of FPGA based partial configuration. In the first part of review
OFDM characteristics of the signal has compared with several optimizations based ISI reduction
techniques. The second part is to compare the various spectrum sensing techniques in cognitive radio
engine and its application in FPGA.
.KEYWORDS
Cognitive radio, Inter symbol interference (ISI), Spectrum sensing, OFDM
1. INTRODUCTION
As the wireless devices and applications are increasing, the available electromagnetic spectrum
becomes increasingly crowded due to limitations of spectrum access. Hence, many studies and
researches have been done in order to utilize the available spectrum efficiently. Therefore, the
concept of opportunistic usage of frequency bands using cognitive radio is introduced. Cognitive
radio is defined as a radio that senses its electromagnetic environment and changes its
transmission or reception parameters dynamically and autonomously [1]. Furthermore, cognitive
radio allows unlicensed users to access licensed frequency bands through dynamic spectrum
access. One of the main function of cognitive radio is spectrum sensing. The most popular
spectrum sensing techniques are classified into two categories: Non-Cooperative and Cooperative
sensing. In non-cooperative sensing, the detection of a Primary User (PU) signal is based on the
received signal at a cognitive radio user, such as energy detection [2], matched filter detection and
cyclo stationary feature detection [3], each of these techniques has its strengths and weaknesses.
In a conventional parallel data system, the total signal bandwidth can be divided into N non-
overlapping frequency sub-channels. Each sub-channel is modulated with a separate symbol and
then the N subchannels are frequency multiplexed. To eliminate the inter-carrier interference
(ICI), a spectral overlap is avoided i.e. empty spectral region is provided, between two adjacent
sub-channels. But this results in inadequate use of the ready spectrum [4]. The concept was
recommended in the mid-1960s, to handle with this wastefulness, through the advancement of
frequency division multiplexing (FDM) with overlapping sub-channels. The sub-channels were

54
ordered so that, the sidebands of the individual carriers overlap without inducing ICI. To
accomplish this, the carriers must be mathematically orthogonal.
Figure-1 Block diagram of sensing the bands and to reduce ISI
It is proficient advanced transmission procedure for fourth Generation correspondence. OFDM is
multicarrier in nature which utilizes the number of subcarriers for multiplexing. These sub-
bearers are orthogonal and are covered with each other. OFDM is better to answer for fast
advanced correspondence. One of the real disadvantages of the OFDM signals is Peak to Average
Power Ratio (PAPR) [5]. The most extreme pinnacle of the transmitted flag happened when
numbers of signs of the same stage are included intelligibly.
With a high measure of PAPR, the power intensifiers work in a non-straight district so it requires
expansive power back-off [6], which makes the framework much costly. In the event that a power
intensifier does not work in direct locale, it is hard to keep out of band radiation underneath a
particular farthest point. This sort of approach includes Selective Mapping (SLM) [7] and Partial
Transmit Sequences (PTS). SLM strategy applies scrambling turn to all sub-transporters
autonomously while the PTS technique just takes scrambling to some portion of the sub-bearers.
2. OPTIMIZATION BASED ISI AND PAPR REDUCTION TECHNIQUES
Kuldeep Singh et al.,[8] proposed a PTS in light of Cuckoo Search (CS) Algorithm (CS-PTS) has
been proposed for a proficient diminishment of PAPR with fewer ventures keeping in mind the
end goal to beat the drawback of the regular PTS. The unmistakable drawbacks of further
expanding the number of sub-pieces are that the time postponement and many-sided quality of
framework increments. It depends on look methodology of a cuckoo feathered creature and it
recreates the forceful regenerative technique of the winged creature. Reenactment result
demonstrates that the CS-PTS stage streamlining plan can accomplish better PAPR lessening.
Huynh et al.,[9] adjusted a manufactured honey bee province (ABC) calculation, which is an
approach in light of arrangement sets to tackle combinatorial and numerical improvement issues
at the underlying advance, stage factor enhancements remember a worldwide ideal stage vector
with the best wellness from the haphazardly delivered stage vectors.
Y. Wang et al..,[10] has thought about computational many-sided quality among the ABC-PTS
and the current PAPR lessening techniques, for example, molecule swarm advancement
calculation based PTS (PSO-PTS), the iterative flipping calculation for PTS (IPTS), slope plunge
seek (GD), and the least separation guided hereditary calculation (MDGA). It is demonstrated that
contrasted with the leaving PAPR diminishment strategies, the ABCPTS calculation has the most

55
reduced scan many-sided quality for bigger PTS sub-obstructs in the meantime and can show
signs of improvement PAPR lessening execution.
Tellado et al., [11] proposed the TR strategy in light of flag to cut-out commotion control
proportion to decrease the many-sided quality of the minimization methodology. The remedial
flag is evaluated by means of these four enhancement solvers, in particular, Gradient calculation,
Fletcher-Reeves and Polak-Ribiere Conjugate-Gradient and Quasi-Newton strategies.
Reproduction comes about on the IEEE 802.11a standard demonstrate that conjugate slope solver
gives better execution in term of PAPR lessening addition and merging pace contrasted with
Quasi-Newton and Gradient calculations.
Eakhwan Song et al.,[12] proposed an advancement technique in light of a logical estimation
strategy for educational and jitter was presented. In spite of the fact that the strategy shows a
quantitative improvement approach, it is less appropriate for complex tuning of the outline
parameters because of the suspicion that voltage-time bend has a perfect direct slant in the
diagnostic estimation. the proposed strategy has been effectively approved with a huge change in
both recurrence and time spaces
3. SPECTRUM SENSING TECHNIQUES
Bahi et al.,[13] proposed another location plan of OFDM PUs signals utilizing Singular Value
Decomposition (SVD) of Second-Order Statistics (SOS) of the got signals at the Secondary Users
(SUs), so as to choose the nearness/nonattendance of OFDM PUs signals. The decision of OFDM
tweak is because of the way that it is all the more broadly utilized as a part of remote interchanges
(e.g. 3GPP/LTE (third Generation Partnership Project/Long Term Evolution) for the downlink,
WiFi, WiMAX (Worldwide Interoperability for Microwave Access), DVBT (Digital Video
Broadcast Terrestrial)), in light of its high transmission capacity productivity.
Ming Liu et al., [14] proposed an accepted spectrum sensing techniques for TDS-OFDM are
focused around the misuse of the PN grouping and therefore experience the ill effects of inter
symbol impedance (ISI). This paper proposes a novel information supported channel estimation
system which joins the channel assessments acquired from the PN arrangement and, above all,
extra channel evaluations separated from OFDM information images. Information helped channel
estimation is completed utilizing the reconstructed OFDM information images as virtual
preparing successions.
Cognitive radio (CR) cannot sense the presence of primary user, and thus it allowed accessing
the channel while the PU is still in operation. To address this issue or to overcome this problem
multiple CRs can be considered to collaborate in spectrum sensing. Khaled Ben Letaif et al..,
found that in cooperative spectrum sensing, all CRs identify the availability of licensed spectrum
individually. Each cooperative partner makes a binary decision based on its local observation and
forward one bit of the decision to the common receiver. As a result OFDM has great advantage
over fading channel so OFDM is very robust against the inter symbol interference (lSI). So we get
higher probability of detection for low Probability of false alarm[15].
In [16], Zhang and Leung proposed a low complexity suboptimal algorithm for an OFDM-based
CR system in which SUs may access both non active and active PU frequency bands, as long as
the total CCI and ACI are within acceptable limits.
Bansal et al. [17] investigated the optimal power allocation problem in CR networks to maximize
the SU downlink transmission capacity under a constraint on the instantaneous interference to

56
PUs. The proposed algorithm was complex and several suboptimal algorithms were developed to
reduce the computational complexity.
4. OFDM WITH FPGA
S. Haene, D. Perels and A Burg [18] recommended that A constant MIMO-OFDM physical layer
transmitting at a pinnacle information rate of 216Mbit/s more than 20MHz transfer speed was
prototyped and described through estimations. Constant operation of the framework on a FPGA
was accomplished by steady choice and enhancement of the utilized handset calculations for the
FPGA usage and via cautious plan of the comparing handset equipment design.
Arun Kumar K An et al.,[19] portrays in the headway of present-day time remote correspondence
frameworks, reconfigurable innovation plays a basic obligation. The Baseband FPGA execution
of an OFDM transmitter is likewise talked about in this paper. The module is executed utilizing a
strategy called fractional reconfiguration with the goal that somebody can swap between
unmistakable tweak strategies, coding systems and number sub-bearers requested in less time. In
this PR based execution of OFDM Transmitter, a more prominent region of the Modulator,
coding and IFFT modules will be static and a lesser zone will be dynamic. At the season of
swapping just the dynamic zone of the FPGA is reconfigured in less time which will diminish
power and setup time.
Veena and Swamy[20] performed the examination of DWT based OFDM over FFT construct
OFDM and actualizing in light of FPGA propose a DWT-IDWT based OFDM transmitter and
recipient that accomplish better execution in wording SNR and BER for AWGN channel. It
demonstrates all the wavelet families better finished the IFFT-FFT usage. The OFDM display is
produced utilizing Simulink, different experiments have been considered to confirm its execution.
FINDINGS:
1. It is powerless against the impacts of frequency offset. OFDM sub-bearer ranges cover one
another, which require strict symmetry among them. Frequency offset impedes symmetry
and can likewise debase demodulation execution. Time balance can prompt OFDM image
impedance and adequacy weakening.
2. The utilization of OFDM presents a high pinnacle normal power proportion. It is realized
that in OFDM, the yield is a superposition of sub-transporters. At the point when the periods
of transporters are the equivalent, this could prompt some quick power yields which are
higher than the mean intensity of the framework. This outcomes in a bigger Peak-to-Average
Power Ratio (PAPR). At the point when the pinnacle control is excessively high, it could be
out of scope of straight power speakers. This offers ascend to non-straight mutilation and
changes the superposition of the flag range. It additionally devastates sub-transporter
symmetry and debases the execution of OFDM.
3. On a very basic level OFDM is a multicarrier transmission system wherein a single
higher rate data transporter is isolated into a considerable number of parallel lower
rate data bearers which are solely called as sub-transporters, hence decreasing the
Inter picture Interference (lSI) in light of gigantic picture length not in any manner
like the standard Frequency Division Multiplexing (FDM) advancement.

57
5. COMPARATIVE EXAMINATION
In this segment different existing Optimization based ISI diminishment strategies are thought
about as far as time delay, The FPGA based arrangement methods is analyzed regarding setup
time, dormancy, control which have confinements and favourable circumstances in different
parameters.
Table 1. Comparison Of Optimization Based Isi And Paper Reduction Techniques
Techniques PAPR Time delay Power
consumption
SNR BER Convergence
rate
Cuckoo Search
(CS)
Algorithm
(CS-PTS)
Better
reduction
less more more moderate Moderate
An artificial
bee colony
(ABC)
algorithm
Considerable
amount of
reduction
More moderate less More Moderate
ABC-PTS Better
reduction
moderate More More Less Less
analytic
estimation
method eye
opening with
optimization
Less
reduction
Moderate Less Moderate More Very less
Singular Value
Decomposition
(SVD)
Moderate
reduction
Less Moderate Less More More
TDS-OFDM Less
reduction
more more Less Moderate Moderate
Table-2 Comparison Of Fpga Configuration Techniques
Methods Configuration time Latency Power Memory
FPGA
prototyped
OFDM
more more Less More
Cordic based
Partially
Reconfigurable
FPGA Module
Very less moderate very less Less
DWT –FPGA
based OFDM
Less more moderate Very less
6. CONCLUSION
In this paper, an overview of different strategies for advancement based ISI lessening systems,
range detecting methods and FPGA arrangement procedures are inspected as far as a
postponement, normal power, SNR and BER. It is extremely surely known that all strategies
function admirably for various purposes. The points of interest and hindrances of these strategies
are talked about. There are sure issues recognized, for example, FPGA incomplete
reconfiguration, however, experiences the ill effects of poor transmission capacity distribution,
which prompts wasteful information exchange systems with expanded power utilization and

58
diminished throughput. Latencies can't be accomplished utilizing a product baseband running
over a working framework or even continuous working framework.
REFERENCES
[1] Q. Zhao and B. M. Sadler, “A survey of dynamic spectrum access,” Signal Processing Magazine,
IEEE, vol. 24, no. 3, pp. 79–89, 2007.
[2] A. Taherpour, M. Nasiri-Kenari, and S. Gazor, “Multiple antenna spectrum sensing in cognitive
radios,” IEEE Transactions on Wireless Communications, vol. 9, no. 2, pp. 814–823, 2010
[3] W. A. Gardner, A. Napolitano, and L. Paura, “Cyclostationarity: Half a century of research,” Signal
processing, vol. 86, no. 4, pp. 639–697, 2006
[4] Anurag Tiwari, SanketPhapal, DhirajKadam, Sivanantham S, Sivasankaran K, “FPGA
Implementation of FFT Blocks for OFDM”, IEEEOnline International Conference on Green
Engineering and Technologies,pp.978-982, 2015.
[5] Nilesh Chide, ShreyasDeshmukh, Prof.P.B.Borole, “Implementation of OFDM System using IFFT
and FFT”, International Journal of Engineering Research and Applications (IJERA), Vol.3, pp.2009-
2013,2013
[6] W. Yajun, W. Chen and C. Tellambura, (2010), “A PAPR reduction method based on artificial bee
colony algorithm for OFDM signals,” IEEE Transactions on Wireless Communications, vol. 9, no.
10,pp. 2994-2999
[7] A. Gangwar and M. Bhardwaj, (2012), “An Overview: Peak to Average Power Ratio in OFDM
system & its Effect,” International Journal of Communication and Computer Technologies, vol. 01,
no. 02, pp. 22-25
[8] Kuldeep Singh, Balraj Singh Sidhu,” PAPR Reduction of OFDM Signals Using Cuckoo Search
Algorithm”, International Journal of Computing and Technology, Volume 2, Issue 2, February 2015.
[9] Huynh hVo Trung Dung, Hakjeon Bang and Seungil Myong,” PAPR Reduction using PTS with Low
Computational Complexity in Coherent Optical OFDM Systems” IEEE Trans. Broadcast., vol. 53, no.
3, pp. 719-724, Sep. 2007
[10] Y. Wang, W. Chen, and C. Tellambura, “A PAPR Reduction Method Based on Artificial Bee Colony
Algorithm for OFDM Signals,” IEEE Trans. Wirel. Commun., vol. 9, no. 10, pp. 2994-2999, Oct.
2010
[11] J. Tellado and J. M. Cioffi, “Peak power reduction for multicarrier transmission,” in Proc. IEEE
GLOBECOM. Conf, 2011
[12] Eakhwan Song, Juyeop Kim, Jiseong Kim,” A Passive Equalizer Optimization Method Based on
Time-Domain Inter-Symbol Interference (ISI) Cancellation Technique” IEEE TRANSACTIONS ON
ELECTROMAGNETIC COMPATIBILITY, 2017 IEEE
[13] F. Z. El Bahi, H. Ghennioui, M. Zouak,” Spectrum Sensing Technique for Cognitive Radio of
Multiple OFDM Signals based on Singular Value Decomposition” 2016, IEEE transactions on
communications, vol. 57, no. 6, pp. 1784–1793

59
[14] Ming Liu, Matthieu Crussière, and Jean-François Hélard, “A Novel Data-Aided Channel Estimation
with Reduced Complexity for TDSOFDM Systems” IEEE Transactions on Broadcasting, VOL. 58,
NO. 2, JUNE 2012 247
[15] Khaled Ben Letaife, Fellow IEEE and Wei Zhang, "Cooperative communications for Cognitive Radio
Networks", proceeding of IEEE, vol-97 No-5 May 2009.
[16] Y. Zhang and C. Leung, “An efficient power-loading scheme for OFDMbased cognitive radio
systems,” IEEE Trans. Veh. Technol., vol. 59, no. 4, pp. 1858–1864, May 2010
[17] G. Bansal, M. Hossain, and V. Bhargava, “Optimal and suboptimal power allocation schemes for
OFDM-based cognitive radio systems,” IEEE Trans. Wireless Commun., vol. 7, no. 11, pp. 4710–
4718, Nov. 2008.
[18] M.A. Mohamed1, A.S. Samarah1, M.I. Fath Allah2, “A Novel implementation of OFDM using
FPGA”, IJCSNS International Journal of Computer Science and Network Security, VOL.11 No.11,
November 2011
[19] Arun Kumar K A, “An OFDM Transmitter Implementation using Cordic based Partially
Reconfigurable IFFT Module”, IEEE3rd International Conference on Eco-friendly Computing and
Communication Systems, pp.266-270,2014.
[20] Mrs. VEENA M.B1 & Dr. M.N.SHANMUKHA SWAMY,” Performance analysis of DWT based
OFDM over FFT based OFDM and implementing on FPGA” International Journal of VLSI design &
Communication Systems (VLSICS) Vol.2, No.3, September 2011.
AUTHOR
Mr.B.MaheswaraRao received his B.Tech in (Electronics & Communication
Engineering) from – Sri Raja Rajeswari Engineering College (JNTUH) in 2006 and
M.Tech (VLSI System Design)-From Hyderabad Institute of Technology & Management
(JNTUH) in 2010 and Advanced Diploma in Data Science and Big Data Analytics from
National Institute of Electronics and Information Technology, Calicut, in March-July
2017, Student Member of IEEE, respectively. Currently, working towards the Ph.D.
degree in Electronics and Communication Engineering, from Veltech Rangarajan
Dr.Sagunthala R&D Institute of Science and Technology, Avadi, Chennai India. His
research interests include VLSI Technology & Design, Wireless Communication and
Networks, MIMO-OFDM, Cognitive Radio Networks.
Dr.S.Baskar received his B.E (Electrical & Electronics Engineeering) from Annamalai
University and M.Tech (Power Electronics) from Vellore Institute of Technology, India.
He has completed his Ph.D – EEE in the specialization area of FACTS controllers from
Annamalai University. He is currently working as Professor in the Department of
Electrical and Electronics Engineering, at Veltech Rangarajan Dr.Sagunthala R&D
Institute of Science and Technology, Avadi, Chennai, India. His research interests include
Power Electronics, Control and Modeling of FACTS Controllers and its application to
power system

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