Research Article Performance on ICI Self-Cancellation in ...downloads.hindawi.com/journals/jfs/2015/854753.pdf · In OFDM system, a er IFFT the transmitted signal can be expressed

Research ArticlePerformance on ICI Self-Cancellation in FFT-OFDM andDCT-OFDM System

Shilpi Gupta1 Upena Dalal1 and Vishnu Narayan Mishra23

1Electronics Engineering Department Sardar Vallabhbhai National Institute of Technology Surat 395 007 India2Applied Mathematics and Humanities Department Sardar Vallabhbhai National Institute of TechnologyIchchhanath Mahadev Dumas Road Surat Gujarat 395 007 India3L 1627 Awadh Puri Colony Beniganj Phase-III Opposite-Industrial Training Institute (ITI) Ayodhya Main RoadFaizabad Uttar Pradesh 224 001 India

Correspondence should be addressed to Vishnu Narayan Mishra vishnunarayanmishragmailcom

Received 21 October 2014 Accepted 9 December 2014

Academic Editor Syed Abdul Mohiuddine

Copyright copy 2015 Shilpi Gupta et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

In orthogonal frequency division multiplexing (OFDM) system the existence of frequency offset in AWGN channel affects theorthogonality among the subcarriers and consequently introduces the intercarrier interference (ICI) The paper investigates newICI self-cancellation technique tomitigate the effect of ICI in FFT-OFDM and compares it to DCT based OFDM system in terms ofbit error rate (BER) and carrier to interference ratio (CIR) The proposed method for group size three results in a significant 20 dBimproved CIR in FFT-OFDM In terms of BER proposed ICI self-cancellation technique outperforms the other self-cancellationtechniques in FFT-OFDM Also this paper investigates outperforming BER and CIR improvement by using DCT-OFDM withoutapplying self-cancellation techniques due to its energy compaction property

1 Introduction

Orthogonal frequency division multiplexing (OFDM) is aspecial form multicarrier (MC) that dates back to 1960s Theconcept of the multicarrier transmission was first clearlyintroduced by Chang in 1966 [1] and its detailed descriptioncan also be found in [2 3] In 1971 Weinstein and Ebert pro-posed an improved OFDM system [4] in which the discreteFourier transform (DFT) was employed to generate orthog-onal subcarriers in place of the bank of demodulators andoscillators This scheme also reduces the system implemen-tation complexity significantly by using the inverse discreteFourier transform (IDFT) and discrete Fourier transform(DFT) In this system model the baseband signal was mod-ulated by IDFT at transmitter side and demodulated by DFTat the receiver side and by using IDFT modulation all thesubcarriers were orthogonal to each other and in frequencydomain they were overlapped

Flexibility of the OFDM system provides opportunitiesto use advanced techniques such as adaptive loading and

transmitter and receiver diversities to improve transmissionefficiency In 1948 Shannon suggested that in frequencyselective channel the highest data rate can be achieved byusing a multicarrier (MC) system with an intensive set ofsubchannels and adapting transmission powers and data ratesaccording to the signal to noise ratio (SNR) at differentsubchannels In 1980 Peled andRuiz proposedOFDMsystemwith cyclic prefix [5] In this the cyclic prefix is used tomaintain the orthogonality among the subcarriers and thisresults in the reduction of intersymbol interference (ISI)and intercarrier interference (ICI) Because in DFT circularconvolution in (discrete) time domain corresponds to multi-plication in (discrete) frequency domain the circular convo-lution is needed and not the regular convolution while thereal channel requires only normal convolution

So if cyclic prefix is used at the place of guard interval thenregular convolution can be used to create circular convolu-tion

In 1980 Hirosaki proposed an equalization algorithmto reduce the intersymbol interference (ISI) and intercarrier

Hindawi Publishing CorporationJournal of Function SpacesVolume 2015 Article ID 854753 7 pageshttpdxdoiorg1011552015854753

2 Journal of Function Spaces

interference (ICI) [6] for the ISI and ICI caused by a channeldistortion synchronization error or phase error In 1985Cimini proposed pilot-based OFDM system [7] to reduce theeffect of multipath propagation and cochannel interferenceon a narrow band digital mobile channel In this by usingpilot signal the effect of flat Rayleigh fading can be reducedsignificantly An improvement in signal to interference ratioof 6 dB can be obtained over the burst Rayleigh channel

In 1990s OFDM system has been exploited for high datarate communication mobile radio channel but it has somedrawbacks One of them is high peak to average power ratio(PAPR) and the second is intercarrier interference (ICI) Soin communication system a number of techniques are used todeal with high PAPR such as clipping clipping and filteringtone reservation tone injection selected mapping and par-tial transmit sequence [8] And to mitigate the effect of ICIin 1999 Jeon et al proposed a frequency domain equalizationICI cancellation scheme [9] This scheme is used when ICI iscaused by fading distortion In this method the pilot subcar-riers are added in between the transmitted data symbols soat the receiver side by using the pattern of pilot subcarrierthe equalization technique is applied In 1999 Armstrong alsoproposed a time domain windowing ICI cancellation scheme[10] and it is only used when the ICI is caused by band limitedchannel In this method a time domain window functionis multiplied at the transmitter side and the same windowfunction is multiplied at the receiver side to reduce the effectof ICI

The above two ICI cancellation schemes are not effectivebecause the major source of ICI is frequency offset due tofrequency mismatch between the transmitter and receiverslocal oscillator and Doppler shift due to relative motionbetween the transmitter and receiver After that new ICI can-cellation schemes are proposed for pulse shaping and ICI self-cancellationThese schemes reduce the effect of ICI caused byfrequency offset

In 2001 Zhao and Haggman introduced an ICI self-cancellation technique [11] In this technique one data symbolis mapped on two subcarriers at transmitter side and atreceiver side these groups of subcarriers are combined so theeffects of ICI on these subcarriers cancel each other Thisscheme is easy to implement but the bandwidth efficiency isreduced And after that different ICI self-cancellation tech-niques are described based on a data symbol mapped on eachof the two subcarriers tomitigate the ICI [12ndash15] In this whena data symbol is mapped on two subcarriers the carrier tointerference ration (CIR) improved by 15 dB And a data sym-bol ismapped on two subcarriers with a predefinedweightingcoefficient So the ICI generated between the subcarriers ismutually cancelled

Orthogonal frequency division multiplexing (OFDM) isthe promising communication technique in the broadbandwireless mobile communication system due to its high spec-tral efficiency and robustness to frequency selective fadingIn OFDMmulticarrier modulation (MC) is used comprisingmultiple numbers of frequency channels known as subcarri-ers and these subcarriers are orthogonal to each other

Currently OFDMhas been employed inmany communi-cation systems such asWireless Local AreaNetwork (WLAN)

system Worldwide Interoperability for Microwave Access(WiMAX) IEEE 80216 Digital Audio Broadcasting (DAB)system Digital Video Broadcasting (DVB) system andHIPERLAN2 (High Performance Local Area Network) LTE(Long-Term Evolution) and UWB (Ultra-Wide Band)

The major problem in OFDM is its carrier frequencyoffset error between the transmitted and received signal dueto the frequency mismatch between the local oscillator ofthe transmitter and the receiver or Doppler shift due torelative motion between the transmitter and receiver Inthis situation the orthogonality among the subcarriers is nolonger maintained that results in introduction of intercarrierinterference (ICI) in OFDM and the performance of thesystem is degraded

Many ICI cancellation schemes have been proposed toimprove the performance of the OFDM system ICI cancel-lation schemes are used to reduce the fading distortion [9]frequency offset and IQ imbalance effect [16] and are alsoeffective when the channel is band limited [10] ICI self-cancellation scheme [11 13 17] is used when ICI is causedby frequency offset where one data symbol is mapped ontogroup of subcarriers to reduce the effect of ICI but thebandwidth efficiency reduced by half when group size is twoIn ICI self-cancellation selection of weighting coefficient [14]is carefully done to reduce the effect of ICI A comparisonof FFT-OFDM and DCT-OFDM is given in [18 19] in termsof CIR and BER where DCT-OFDM system prevails due toenergy compaction property [20] Deepmala [21] andMishra[22] have discussed approximations of signals (functions)using fixed point theorems (PD-operator) and summabilityoperators as double digital filter Acar et al [23] andHusain etal [24] also studied approximation properties of certain oper-ators and generalized 119867(sdot sdot sdot)-120578-cocoercive operators andgeneralized set-valued variational-like inclusions and theirapplications in engineering fields Deepmala [25] studied theexistence theorems for solvability of a functional equationarising in dynamic programming Gupta et al [26] discussedanalytical approach of nonconventional mapping schemewith discrete Hartley transform in OFDM system

In this paper an ICI self-cancellation scheme has beenproposed where one data symbol is mapped on three sub-carriers which improves CIR and BER while the bandwidthefficiency reduced by one third The organization of paper isas follows OFDM system model is described in Section 2The next section analyzes ICI in FFT-OFDM system whileSection 4 will help to understand the ICI self-cancellation inFFT-OFDM followed by an important discussion of proposedscheme in Section 5 Analysis of ICI inDCT-OFDMsystem iscovered in Section 6 the last two sections produce simulationresults and conclusion as Sections 7 and 8 respectively

2 System Model

A high data rate serial input bit stream is converted into aparallel lower data rate bit stream and passes through thesignal mapper where modulation (MPSK QAM) is doneand fed into IFFTIDCT Cyclic prefix is used to removeintersymbol interference (ISI) and converted from parallel toserial and fed into the channel At the receiver side original

Journal of Function Spaces 3

Input bit stream Serial to parallel

Signal mapper (modulation)

IFFT or IDCT

Add cyclic prefix

Parallel to serial

AWGN channel

w(n)

Output bit stream Parallel to serial

Signal demapper (demodulation)

FFT or DCT

Remove cyclic prefix

Serial to parallel

exp(j2120587n120576N)

Figure 1 Block diagram of OFDM system model

bit stream is retrieved by applying the reverse process of whatwas done at the transmitter It has been shown in Figure 1

3 ICI Analysis of FFT-OFDM System

In OFDM system after IFFT the transmitted signal can beexpressed as

119909 (119899) =1119873

119873minus1sum

119905=0119883 (119905) 119890

1198952120587119899119905119873 (1)

where 119909(119899) represents the time domain 119899th sample of theOFDM transmitted signal 119873 is the total number of OFDMsubcarriers and 119883(119905) represents the modulated symbol infrequency domain for the 119905th subcarrier where 0 le 119905 le 119873minus1

The received signal after passing through the AWGNchannel affected by frequency offset

119910 (119899) = 119909 (119899) 1198901198952120587119899120576119873

+ 119908 (119899) (2)

where 120576 represents the normalized frequency offset and it isgiven byΔ119891119873119879

119904 whereΔ119891 is the frequency difference of local

oscillator between the transmitter and receiver and 119879119904is the

symbol period119908(119899) is theAWGNnoise added to the channelThe received signal after taking FFT in frequency domain

at the 119896th subcarrier can be expressed as

119884 (119896) =

119873minus1sum

119899=0119910 (119899) 119890

minus1198952120587119896119899119873 (3)

The received signal on the 119896th subcarrier can be furtherexpressed as

119884 (119896) = 119883 (119896) 119878 (0)⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

Desired signal+

119873minus1sum

119905=0119905 =119896119883 (119905) 119878 (119905 minus 119896)

⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

ICI signal

+119882(119896) (4)

In this equation right hand side first term of it representsthe desired signal and second term represents ICI signal for

119896th subcarrier 119882(119896) is the FFT of 119908(119899) and 119878(119905 minus 119896) is thecomplex ICI coefficient between the 119905th and 119896th subcarrier inthe received signal These coefficients are expressed as

119878 (119905 minus 119896) =sin [120587 (119905 + 120576 minus 119896)]

119873 sin [120587 (119905 + 120576 minus 119896) 119873]

sdot exp [119895120587 (119905 + 120576 minus 119896) (1 minus 1119873)]

(5)

The carrier to interference ratio (CIR) is the ratio of the signalpower to the power in the ICI component It indicates thequality of the signal If the received signal on the 0th subcar-rier is considered then the carrier to interference ratio (CIR)of OFDM system is given as

CIR =

119864 [|119862 (119896)|2]

119864 [|ICI (119896)|2]=

|119878 (119896)|2

sum119873minus1119905=0119905 =119896 |119878 (119905 minus 119896)|

2

=|119878 (0)|2

sum119873minus1119905=1 |119878 (119905)|

2

(6)

And CIR (in dB) of OFDM system depends on normalizedfrequency offset (Figure 2)

4 ICI Self-Cancellation in FFT-OFDM System

In ICI self-cancellation one data symbol is mapped on groupof subcarriers with predefined weighting coefficient Theweighting coefficients are carefully selected so that at thereceiver side the ICI signals within the group of subcarriersare cancelled by each other

41 ICI Self-Cancellation Scheme In this ICI self-cancellationone data symbol is mapped on two consecutive subcarriersto mitigate ICI Then transmitted data symbols are 119883(1) =

minus119883(0) 119883(3) = minus119883(2) 119883(119873 minus 1) = minus119883(119873 minus 2) Furtherthe received signal 119884(119896) is determined by the differencebetween two adjacent subcarriers So the difference between


0 005 015 025 035 045

0

10

20

30

40

50

60

70

80

FFT OFDM

Proposed

Normalized freq offset

CIR

(dB)

minus10

04030201

ICI SC

Figure 2 CIR versus normalized freq offset

adjacent ICI coefficients is very small [119878(119905 minus 119896) minus 119878(119905 + 1 minus

119896)] and the generated ICI signal on 119905th subcarrier will becancelled significantly by the generated ICI signal on (119905+1)thsubcarrierThe received signal on 119896th and (119896+1)th subcarrieris

1198841015840(119896) =

119873minus2sum

119905=024119883 (119905) [119878 (119905 minus 119896) minus 119878 (119905 + 1 minus 119896)] + 119882

1015840(119896)

1198841015840(119896 + 1) =

119873minus2sum

119905=024119883 (119905) [119878 (119905 minus 119896 minus 1) minus 119878 (119905 minus 119896)]

+ 1198821015840(119896 + 1)

(7)

To further reduce the ICI received signal on (119896 + 1)thsubcarrier it is subtracted from the 119896th subcarrier where 119896is even number Consider

11988410158401015840(119896) =

12[1198841015840(119896) minus 119884

1015840(119896 + 1)]

=12[119883 (119896) 2119878 (0) minus 119878 (1) minus 119878 (minus1)

+

119873minus2sum

119905=02119905 =119896

119883 (119905) 2119878 (119905 minus 119896) minus 119878 (119905 + 1 minus 119896)

minus 119878 (119905 minus 119896 minus 1)] +11988210158401015840(119896)

(8)

And the CIR of ICI self-cancellation is higher than standardOFDM expressed as

CIR =|2119878 (0) minus 119878 (1) minus 119878 (minus1)|2

sum119873minus2119905=246 |2119878 (119905) minus 119878 (119905 + 1) minus 119878 (119905 minus 1)|2

(9)

5 Proposed ICI Self-Cancellation Scheme

In this ICI self-cancellation one data symbol is mappedon three consecutive subcarriers to mitigate ICI Thentransmitted data symbols are 119883(1) = minus119883(0) 119883(2) =

minus119883(0) 119883(119873 minus 2) = minus119883(119873 minus 3) 119883(119873 minus 1) = minus119883(119873 minus 3)Then the received signal 119884(119896) is determined by the differenceamong three adjacent subcarriers The received signal on 119896thsubcarrier is written as

1198841015840(119896)

=

119873minus3sum

119905=03119883 (119905) [119878 (119905 minus 119896) minus 119878 (119905 + 1 minus 119896) minus 119878 (119905 + 2 minus 119896)]

+ 1198821015840(119896)

(10)

Similarly the received signal on (119896+1)th subcarrier is writtenas

1198841015840(119896 + 1)

=

119873minus3sum

119905=03119883 (119905) [119878 (119905 minus 119896 minus 1) minus 119878 (119905 minus 119896) minus 119878 (119905 + 1 minus 119896)]

+ 1198821015840(119896 + 1)

(11)

And similarly the received signal on (119896 + 2)th subcarrier iswritten as

1198841015840(119896 + 2)

=

119873minus3sum

119905=03119883 (119905) [119878 (119905 minus 119896 minus 2) minus 119878 (119905 minus 119896 minus 1) minus 119878 (119905 minus 119896)]

+ 1198821015840(119896 + 2)

(12)

To further reduce the ICI received signal on (119896 + 1)th and(119896 + 2)th subcarrier is subtracted from the 119896th subcarrier

11988410158401015840(119896) =

13[1198841015840(119896) minus 119884

1015840(119896 + 1) minus 119884

1015840(119896 + 2)]

=1

3[119883 (119896) 3119878 (0) minus 119878 (2) minus 119878 (minus2) 119905

+

119873minus3

sum

119905=03

119905 =119896



(13)

CIR of this ICI self-cancellation is written as



(14)


6 ICI Analysis in DCT-OFDM System

InDCT-OFDMsystem after IDCT the transmitted signal canbe expressed as

119909119899= radic

2119873

119873minus1sum

119905=0120573119905119889119905cos(120587119905 (2119899 + 1)

2119873) (15)

where 119909119899represents the 119899th sample of the OFDM transmitted

signal119873 is the total number of DCT-OFDM subcarriers and119889119905represents the modulated symbol for the 119905th subcarrier

where 0 le 119905 le 119873 minus 1 And

120573119905=

1radic2

119905 = 0

1 119905 = 1 2 119873 minus 1(16)

The received signal after passing through the AWGN channelaffected by the frequency offset is

119910119899= 119909119899cos(2120587119899120576

119873) + 119908 (119899) (17)

The received signal after taking DCT on the 119896th subcarriercan be expressed as

119910119896= radic

2119873120573119896

119873minus1sum

119899=0119910119899cos(120587119896 (2119899 + 1)

2119873) (18)

where

120573119896=

1radic2

119896 = 0

1 119896 = 1 2 119873 minus 1(19)

It can be further expressed as

119910119896= 119889119896120573119896119878119896119896

+

119873minus1sum

119905=0119905 =119896119889119905120573119905119878119905119896

+119882(119896) (20)

where in the right side first part represents desired signalsecond part represents ICI signal and 119882(119896) is the DCT of119908(119899) In second part 119878

119905119896is the ICI coefficient between the

119905th and 119896th subcarrier in the received signal and it can beexpressed as

119878119905119896

=12119873

120573119896

sdot

119873minus1sum

119899=0cos(120587 (119886119887 + 119889)

2119873) + cos(120587 (119886119888 + 119889)

2119873)

+ cos(120587 (119886119887 minus 119889)

2119873) + cos(120587 (119886119888 minus 119889)

2119873)

(21)

119886 = 2119899 + 1

119887 = 119905 + 119896

119888 = 119905 minus 119896

119889 = 4119899120576

(22)

0

50

100

150

200

250

FFT OFDM Proposed

CIR

(dB)

minus500 005 015 025 035 045

Normalized freq offset04030201

ICI SCDCT OFDM

Figure 3 CIR versus normalized freq offset (0th subcarrier index)

The received signal on 119896th subcarrier is considered then CIRof DCT-OFDM is expressed as

CIRDCT =

119864 [|119862 (119896)|2]

119864 [|ICI (119896)|2]=

10038161003816100381610038161198781198961198961003816100381610038161003816

2

sum119873minus1119905=0119905 =119896

10038161003816100381610038161198781199051198961003816100381610038161003816

2 (23)

7 Simulation Results

In this section the simulations have been shown for FFT-OFDM with and without ICI self-cancellation proposed ICIself-cancellation and DCT-OFDM Figures 3 and 4 show theCIR versus normalized frequency offset (0 le 120576 le 03) for allFFT-OFDMandDCT-OFDM for total number of subcarriers119873 = 64 are used It can be observed that the proposed ICI self-cancellation scheme has the higher value of CIR than existingself-cancellationmethodwhile it compares toDCT-OFDMat0th subcarrier and then DCT-OFDM has the higher CIR forall offset values shown in Table 1

Considering the scenario at 63rd subcarrier for DCT-OFDMCIR is higher when offset value is less than or equal to004 due to energy compaction property and for higher offsetvalue proposed method has high value of CIR (Table 2)

8 Conclusion

In this paper a new ICI self-cancellation scheme is proposedto mitigate the effect of frequency offset The proposedschemeperforms better than the existing ICI self-cancellationin FFT-OFDM Improvement in CIR is 3 dB to 4 dB Whileit compares to DCT-OFDM the DCT-OFDM gives goodresults without ICI self-cancellation in terms of CIR (at lowersubcarrier index) and at higher value of subcarrier index(worst case) DCT-OFDM performance is poor comparedto proposed ICI self-cancellation scheme Some interestingapplications of the FFT-OFDM andDCT-OFDM can be seenin [21 22]


Table 1 CIR comparison among all FFT-OFDM and DCT-OFDM at the first (0th) subcarrier

Normalized freqoffset FFT-OFDM CIR (dB) FFT-OFDM with SC GS2

CIR (dB)FFT-OFDM with proposed

SC CIR (dB)DCT-OFDM CIR

(dB)01 151044 326236 367266 125412402 86474 257274 295058 113045103 46120 211125 243512 1059674

Table 2 CIR comparison among all FFT-OFDM and DCT-OFDM at the last (63th) subcarrier




(dB)003 265240 441881 483871 525000004 236921 413454 455374 468288005 215560 391950 433778 425466007 184010 360016 401591 362092009 160756 336250 377484 315205015 113572 286844 326523 218958030 46120 211125 243512 70959

0

20

40

60

80

100

120

CIR

(dB)

minus20

FFT OFDM Proposed

0 005 015 025 035 045Normalized freq offset

04030201

ICI SCDCT OFDM

Figure 4CIR versus normalized freq offset (63th subcarrier index)

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Authorsrsquo Contribution

All the authors carried out the preparation of the presentpaper Each author contributed equally in the developmentof the paper Shilpi Gupta and Vishnu N Mishra conceivedthe study and participated in its design and coordination Allthe authors drafted the paper participated in the sequencealignment and read and approved the final version of thepaper

Acknowledgments

The authors are very grateful to the editorial board membersand the reviewers of esteemed journal for their deep observa-tions and pertinent suggestions which greatly helped them toimprove the paper significantly Special thanks are due to theeditor Professor Syed Abdul Mohiuddine for his efforts tosend the reports of the paper timely

References

[1] R W Chang ldquoSynthesis of band-limited orthogonal signals formulti-channel data transmissionrdquo Bell Labs Technical Journalvol 45 pp 1775ndash1797 1966

[2] R W Chang ldquoOrthogonal frequency division multiplexingrdquoUS Patent 3388455 January 1970 Filed November 1966

[3] B R Satzberg ldquoPerformance of an efficient parallel data trans-mission systemrdquo IEEETransactions onCommunication Technol-ogy vol 15 no 6 pp 805ndash811 1967

[4] S Weinstein and P Ebert ldquoData transmission by frequencydivision multiplexing using the discrete Fourier transformrdquoIEEE Transactions on Communications vol 19 no 5 pp 628ndash634 1971

[5] A Peled and A Ruiz ldquoFrequency domain data transmissionusing reduced computational complexity algorithmsrdquo in Pro-ceedings of the IEEE International Conference on AcousticsSpeech and Signal Processing (ICASSP rsquo80) vol 5 pp 964ndash967April 1980

[6] B Hirosaki ldquoAn analysis of automatic equalizers for orthogo-nally multiplexed QAM systemsrdquo IEEE transactions on commu-nications systems vol 28 no 1 pp 73ndash83 1980

[7] L J Cimini ldquoAnalysis and simulation of a digital mobile chan-nel using orthogonal Frequency division multiplexingrdquo IEEETransactions on Communications vol 33 no 7 pp 665ndash6751985

[8] S H Han and J H Lee ldquoAn overview of peak-to-average powerratio reduction techniques for multicarrier transmissionrdquo IEEEWireless Communications vol 12 no 2 pp 56ndash65 2005


[9] W G Jeon K H Chang and Y S Cho ldquoAn equalizationtechnique for orthogonal frequency-division multiplexing sys-tems in time-variant multipath channelsrdquo IEEE Transactions onCommunications vol 47 no 1 pp 27ndash32 1999

[10] J Armstrong ldquoAnalysis of new and existing methods of reduc-ing intercarrier interference due to carrier frequency offset inOFDMrdquo IEEE Transactions on Communications vol 47 no 3pp 365ndash369 1999

[11] Y Zhao and S G Haggman ldquoIntercarrier interference self-cancellation scheme for OFDM mobile communication sys-temsrdquo IEEE Transactions on Communications vol 49 no 7 pp1185ndash1191 2001

[12] C-P Li andW-WHu ldquoPilot-aided ICI self-cancellation schemefor OFDM systemsrdquo IEICE Transactions on Communicationsvol 89 no 3 pp 955ndash958 2006

[13] Y-H Peng Y-C Kuo G-R Lee and J-H Wen ldquoPerformanceanalysis of a new ICI-self-cancellation-scheme in OFDM sys-temsrdquo IEEE Transactions on Consumer Electronics vol 53 no4 pp 1333ndash1338 2007

[14] S Qiang Y Fang and M Wang ldquoA novel ICI self-cancellationscheme for OFDM systemsrdquo in Proceedings of the 5th Interna-tional Conference onWireless Communications Networking andMobile Computing (WiCOM rsquo09) pp 1ndash4 IEEE Beijing ChinaSeptember 2009

[15] A Bishnu A Jain and A Shrivastava ldquoA new scheme of ICIself-cancellation in OFDM systemrdquo in Proceedings of the 3rdInternational Conference on Communication Systems and Net-work Technologies (CSNT rsquo13) pp 120ndash123 IEEE April 2013

[16] K Sathananthan C R N Athaudage and B Qiu ldquoA novelICI cancellation scheme to reduce both frequency offset andIQ imbalance effects in OFDMrdquo in Proceedings of the 9thInternational Symposium on Computers and Communications(ISCC rsquo04) vol 2 pp 708ndash713 July 2004

[17] A Seyedi and G J Saulnier ldquoGeneral ICI self-cancellationscheme for OFDM systemsrdquo IEEE Transactions on VehicularTechnology vol 54 no 1 pp 198ndash210 2005

[18] P Tan and N C Beaulieu ldquoA comparison of DCT-basedOFDM and DFT-based OFDM in frequency offset and fadingchannelsrdquo IEEETransactions onCommunications vol 54 no 11pp 2113ndash2125 2006

[19] D Gupta V B Vats and K K Garg ldquoPerformance analysisof DFT-OFDM DCT-OFDM and DWT-OFDM systems inAWGN channelrdquo in Proceedings of the 4th International Con-ference on Wireless and Mobile Communications (ICWMC rsquo08)pp 214ndash216 Athens Greece August 2008

[20] A V Oppenheim R W Schafer and J R Buck Discrete-TimeSignal Processing Prentice Hall EnglewoodCliffs NJ USA 2ndedition 1998

[21] Deepmala A study on fixed point theorems for nonlinearcontractions and its applications [PhD thesis] Pt RavishankarShukla University Raipur India 2014

[22] V N Mishra Some problems on approximations of functionsin banach spaces [PhD thesis] Indian Institute of TechnologyUttarakhand India 2007

[23] T Acar L N Mishra and V N Mishra ldquoSimultaneous approx-imation for generalized Srivastava-Gupta operatorsrdquo Journal ofFunction Spaces vol 2015 Article ID 936308 11 pages 2015

[24] S Husain S Gupta and V N Mishra ldquoGeneralized 119867(sdot sdot sdot)-120578-cocoercive operators and generalized set-valued variational-like inclusionsrdquo Journal of Mathematics vol 2013 Article ID738491 10 pages 2013

[25] Deepmala ldquoExistence theorems for solvability of a functionalequation arising in dynamic programmingrdquo International Jour-nal of Mathematics andMathematical Sciences vol 2014 ArticleID 706585 9 pages 2014

[26] S Gupta U D Dalal and V N Mishra ldquoNovel analyticalapproach of non conventional mapping scheme with discreteHartley transform in OFDM systemrdquo American Journal ofOperations Research vol 4 pp 281ndash292 2014

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interference (ICI) [6] for the ISI and ICI caused by a channeldistortion synchronization error or phase error In 1985Cimini proposed pilot-based OFDM system [7] to reduce theeffect of multipath propagation and cochannel interferenceon a narrow band digital mobile channel In this by usingpilot signal the effect of flat Rayleigh fading can be reducedsignificantly An improvement in signal to interference ratioof 6 dB can be obtained over the burst Rayleigh channel

In 1990s OFDM system has been exploited for high datarate communication mobile radio channel but it has somedrawbacks One of them is high peak to average power ratio(PAPR) and the second is intercarrier interference (ICI) Soin communication system a number of techniques are used todeal with high PAPR such as clipping clipping and filteringtone reservation tone injection selected mapping and par-tial transmit sequence [8] And to mitigate the effect of ICIin 1999 Jeon et al proposed a frequency domain equalizationICI cancellation scheme [9] This scheme is used when ICI iscaused by fading distortion In this method the pilot subcar-riers are added in between the transmitted data symbols soat the receiver side by using the pattern of pilot subcarrierthe equalization technique is applied In 1999 Armstrong alsoproposed a time domain windowing ICI cancellation scheme[10] and it is only used when the ICI is caused by band limitedchannel In this method a time domain window functionis multiplied at the transmitter side and the same windowfunction is multiplied at the receiver side to reduce the effectof ICI

The above two ICI cancellation schemes are not effectivebecause the major source of ICI is frequency offset due tofrequency mismatch between the transmitter and receiverslocal oscillator and Doppler shift due to relative motionbetween the transmitter and receiver After that new ICI can-cellation schemes are proposed for pulse shaping and ICI self-cancellationThese schemes reduce the effect of ICI caused byfrequency offset

In 2001 Zhao and Haggman introduced an ICI self-cancellation technique [11] In this technique one data symbolis mapped on two subcarriers at transmitter side and atreceiver side these groups of subcarriers are combined so theeffects of ICI on these subcarriers cancel each other Thisscheme is easy to implement but the bandwidth efficiency isreduced And after that different ICI self-cancellation tech-niques are described based on a data symbol mapped on eachof the two subcarriers tomitigate the ICI [12ndash15] In this whena data symbol is mapped on two subcarriers the carrier tointerference ration (CIR) improved by 15 dB And a data sym-bol ismapped on two subcarriers with a predefinedweightingcoefficient So the ICI generated between the subcarriers ismutually cancelled

Orthogonal frequency division multiplexing (OFDM) isthe promising communication technique in the broadbandwireless mobile communication system due to its high spec-tral efficiency and robustness to frequency selective fadingIn OFDMmulticarrier modulation (MC) is used comprisingmultiple numbers of frequency channels known as subcarri-ers and these subcarriers are orthogonal to each other

Currently OFDMhas been employed inmany communi-cation systems such asWireless Local AreaNetwork (WLAN)

system Worldwide Interoperability for Microwave Access(WiMAX) IEEE 80216 Digital Audio Broadcasting (DAB)system Digital Video Broadcasting (DVB) system andHIPERLAN2 (High Performance Local Area Network) LTE(Long-Term Evolution) and UWB (Ultra-Wide Band)

The major problem in OFDM is its carrier frequencyoffset error between the transmitted and received signal dueto the frequency mismatch between the local oscillator ofthe transmitter and the receiver or Doppler shift due torelative motion between the transmitter and receiver Inthis situation the orthogonality among the subcarriers is nolonger maintained that results in introduction of intercarrierinterference (ICI) in OFDM and the performance of thesystem is degraded

Many ICI cancellation schemes have been proposed toimprove the performance of the OFDM system ICI cancel-lation schemes are used to reduce the fading distortion [9]frequency offset and IQ imbalance effect [16] and are alsoeffective when the channel is band limited [10] ICI self-cancellation scheme [11 13 17] is used when ICI is causedby frequency offset where one data symbol is mapped ontogroup of subcarriers to reduce the effect of ICI but thebandwidth efficiency reduced by half when group size is twoIn ICI self-cancellation selection of weighting coefficient [14]is carefully done to reduce the effect of ICI A comparisonof FFT-OFDM and DCT-OFDM is given in [18 19] in termsof CIR and BER where DCT-OFDM system prevails due toenergy compaction property [20] Deepmala [21] andMishra[22] have discussed approximations of signals (functions)using fixed point theorems (PD-operator) and summabilityoperators as double digital filter Acar et al [23] andHusain etal [24] also studied approximation properties of certain oper-ators and generalized 119867(sdot sdot sdot)-120578-cocoercive operators andgeneralized set-valued variational-like inclusions and theirapplications in engineering fields Deepmala [25] studied theexistence theorems for solvability of a functional equationarising in dynamic programming Gupta et al [26] discussedanalytical approach of nonconventional mapping schemewith discrete Hartley transform in OFDM system

In this paper an ICI self-cancellation scheme has beenproposed where one data symbol is mapped on three sub-carriers which improves CIR and BER while the bandwidthefficiency reduced by one third The organization of paper isas follows OFDM system model is described in Section 2The next section analyzes ICI in FFT-OFDM system whileSection 4 will help to understand the ICI self-cancellation inFFT-OFDM followed by an important discussion of proposedscheme in Section 5 Analysis of ICI inDCT-OFDMsystem iscovered in Section 6 the last two sections produce simulationresults and conclusion as Sections 7 and 8 respectively

2 System Model

A high data rate serial input bit stream is converted into aparallel lower data rate bit stream and passes through thesignal mapper where modulation (MPSK QAM) is doneand fed into IFFTIDCT Cyclic prefix is used to removeintersymbol interference (ISI) and converted from parallel toserial and fed into the channel At the receiver side original




IFFT or IDCT

Add cyclic prefix

Parallel to serial

AWGN channel

w(n)



FFT or DCT


Serial to parallel

exp(j2120587n120576N)





119909 (119899) =1119873

119873minus1sum

119905=0119883 (119905) 119890

1198952120587119899119905119873 (1)



119910 (119899) = 119909 (119899) 1198901198952120587119899120576119873

+ 119908 (119899) (2)






119884 (119896) =

119873minus1sum

119899=0119910 (119899) 119890

minus1198952120587119896119899119873 (3)


119884 (119896) = 119883 (119896) 119878 (0)⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

Desired signal+

119873minus1sum

119905=0119905 =119896119883 (119905) 119878 (119905 minus 119896)

⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

ICI signal

+119882(119896) (4)



119878 (119905 minus 119896) =sin [120587 (119905 + 120576 minus 119896)]

119873 sin [120587 (119905 + 120576 minus 119896) 119873]


(5)


CIR =

119864 [|119862 (119896)|2]

119864 [|ICI (119896)|2]=

|119878 (119896)|2

sum119873minus1119905=0119905 =119896 |119878 (119905 minus 119896)|

2

=|119878 (0)|2

sum119873minus1119905=1 |119878 (119905)|

2

(6)







0 005 015 025 035 045

0

10

20

30

40

50

60

70

80

FFT OFDM

Proposed


CIR

(dB)

minus10

04030201

ICI SC




1198841015840(119896) =

119873minus2sum


1015840(119896)

1198841015840(119896 + 1) =

119873minus2sum


+ 1198821015840(119896 + 1)

(7)


11988410158401015840(119896) =

12[1198841015840(119896) minus 119884

1015840(119896 + 1)]


+

119873minus2sum

119905=02119905 =119896



(8)




(9)




1198841015840(119896)

=

119873minus3sum


+ 1198821015840(119896)

(10)


1198841015840(119896 + 1)

=

119873minus3sum


+ 1198821015840(119896 + 1)

(11)


1198841015840(119896 + 2)

=

119873minus3sum


+ 1198821015840(119896 + 2)

(12)


11988410158401015840(119896) =

13[1198841015840(119896) minus 119884

1015840(119896 + 1) minus 119884

1015840(119896 + 2)]

=1


+

119873minus3

sum

119905=03

119905 =119896



(13)




(14)




119909119899= radic

2119873

119873minus1sum

119905=0120573119905119889119905cos(120587119905 (2119899 + 1)

2119873) (15)




120573119905=

1radic2

119905 = 0

1 119905 = 1 2 119873 minus 1(16)


119910119899= 119909119899cos(2120587119899120576

119873) + 119908 (119899) (17)


119910119896= radic

2119873120573119896

119873minus1sum

119899=0119910119899cos(120587119896 (2119899 + 1)

2119873) (18)

where

120573119896=

1radic2

119896 = 0

1 119896 = 1 2 119873 minus 1(19)


119910119896= 119889119896120573119896119878119896119896

+

119873minus1sum

119905=0119905 =119896119889119905120573119905119878119905119896

+119882(119896) (20)




119878119905119896

=12119873

120573119896

sdot

119873minus1sum

119899=0cos(120587 (119886119887 + 119889)

2119873) + cos(120587 (119886119888 + 119889)

2119873)

+ cos(120587 (119886119887 minus 119889)

2119873) + cos(120587 (119886119888 minus 119889)

2119873)

(21)

119886 = 2119899 + 1

119887 = 119905 + 119896

119888 = 119905 minus 119896

119889 = 4119899120576

(22)

0

50

100

150

200

250

FFT OFDM Proposed

CIR

(dB)

minus500 005 015 025 035 045


ICI SCDCT OFDM



CIRDCT =

119864 [|119862 (119896)|2]

119864 [|ICI (119896)|2]=

10038161003816100381610038161198781198961198961003816100381610038161003816

2

sum119873minus1119905=0119905 =119896

10038161003816100381610038161198781199051198961003816100381610038161003816

2 (23)




8 Conclusion







(dB)01 151044 326236 367266 125412402 86474 257274 295058 113045103 46120 211125 243512 1059674





(dB)003 265240 441881 483871 525000004 236921 413454 455374 468288005 215560 391950 433778 425466007 184010 360016 401591 362092009 160756 336250 377484 315205015 113572 286844 326523 218958030 46120 211125 243512 70959

0

20

40

60

80

100

120

CIR

(dB)

minus20

FFT OFDM Proposed


04030201

ICI SCDCT OFDM






Acknowledgments


References



































Volume 2014




Journal of











Journal of


Function Spaces






Algebra












IFFT or IDCT

Add cyclic prefix

Parallel to serial

AWGN channel

w(n)



FFT or DCT


Serial to parallel

exp(j2120587n120576N)





119909 (119899) =1119873

119873minus1sum

119905=0119883 (119905) 119890

1198952120587119899119905119873 (1)



119910 (119899) = 119909 (119899) 1198901198952120587119899120576119873

+ 119908 (119899) (2)






119884 (119896) =

119873minus1sum

119899=0119910 (119899) 119890

minus1198952120587119896119899119873 (3)


119884 (119896) = 119883 (119896) 119878 (0)⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

Desired signal+

119873minus1sum

119905=0119905 =119896119883 (119905) 119878 (119905 minus 119896)

⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

ICI signal

+119882(119896) (4)



119878 (119905 minus 119896) =sin [120587 (119905 + 120576 minus 119896)]

119873 sin [120587 (119905 + 120576 minus 119896) 119873]


(5)


CIR =

119864 [|119862 (119896)|2]

119864 [|ICI (119896)|2]=

|119878 (119896)|2

sum119873minus1119905=0119905 =119896 |119878 (119905 minus 119896)|

2

=|119878 (0)|2

sum119873minus1119905=1 |119878 (119905)|

2

(6)







0 005 015 025 035 045

0

10

20

30

40

50

60

70

80

FFT OFDM

Proposed


CIR

(dB)

minus10

04030201

ICI SC




1198841015840(119896) =

119873minus2sum


1015840(119896)

1198841015840(119896 + 1) =

119873minus2sum


+ 1198821015840(119896 + 1)

(7)


11988410158401015840(119896) =

12[1198841015840(119896) minus 119884

1015840(119896 + 1)]


+

119873minus2sum

119905=02119905 =119896



(8)




(9)




1198841015840(119896)

=

119873minus3sum


+ 1198821015840(119896)

(10)


1198841015840(119896 + 1)

=

119873minus3sum


+ 1198821015840(119896 + 1)

(11)


1198841015840(119896 + 2)

=

119873minus3sum


+ 1198821015840(119896 + 2)

(12)


11988410158401015840(119896) =

13[1198841015840(119896) minus 119884

1015840(119896 + 1) minus 119884

1015840(119896 + 2)]

=1


+

119873minus3

sum

119905=03

119905 =119896



(13)




(14)




119909119899= radic

2119873

119873minus1sum

119905=0120573119905119889119905cos(120587119905 (2119899 + 1)

2119873) (15)




120573119905=

1radic2

119905 = 0

1 119905 = 1 2 119873 minus 1(16)


119910119899= 119909119899cos(2120587119899120576

119873) + 119908 (119899) (17)


119910119896= radic

2119873120573119896

119873minus1sum

119899=0119910119899cos(120587119896 (2119899 + 1)

2119873) (18)

where

120573119896=

1radic2

119896 = 0

1 119896 = 1 2 119873 minus 1(19)


119910119896= 119889119896120573119896119878119896119896

+

119873minus1sum

119905=0119905 =119896119889119905120573119905119878119905119896

+119882(119896) (20)




119878119905119896

=12119873

120573119896

sdot

119873minus1sum

119899=0cos(120587 (119886119887 + 119889)

2119873) + cos(120587 (119886119888 + 119889)

2119873)

+ cos(120587 (119886119887 minus 119889)

2119873) + cos(120587 (119886119888 minus 119889)

2119873)

(21)

119886 = 2119899 + 1

119887 = 119905 + 119896

119888 = 119905 minus 119896

119889 = 4119899120576

(22)

0

50

100

150

200

250

FFT OFDM Proposed

CIR

(dB)

minus500 005 015 025 035 045


ICI SCDCT OFDM



CIRDCT =

119864 [|119862 (119896)|2]

119864 [|ICI (119896)|2]=

10038161003816100381610038161198781198961198961003816100381610038161003816

2

sum119873minus1119905=0119905 =119896

10038161003816100381610038161198781199051198961003816100381610038161003816

2 (23)




8 Conclusion







(dB)01 151044 326236 367266 125412402 86474 257274 295058 113045103 46120 211125 243512 1059674





(dB)003 265240 441881 483871 525000004 236921 413454 455374 468288005 215560 391950 433778 425466007 184010 360016 401591 362092009 160756 336250 377484 315205015 113572 286844 326523 218958030 46120 211125 243512 70959

0

20

40

60

80

100

120

CIR

(dB)

minus20

FFT OFDM Proposed


04030201

ICI SCDCT OFDM






Acknowledgments


References



































Volume 2014




Journal of











Journal of


Function Spaces






Algebra










0 005 015 025 035 045

0

10

20

30

40

50

60

70

80

FFT OFDM

Proposed


CIR

(dB)

minus10

04030201

ICI SC




1198841015840(119896) =

119873minus2sum


1015840(119896)

1198841015840(119896 + 1) =

119873minus2sum


+ 1198821015840(119896 + 1)

(7)


11988410158401015840(119896) =

12[1198841015840(119896) minus 119884

1015840(119896 + 1)]


+

119873minus2sum

119905=02119905 =119896



(8)




(9)




1198841015840(119896)

=

119873minus3sum


+ 1198821015840(119896)

(10)


1198841015840(119896 + 1)

=

119873minus3sum


+ 1198821015840(119896 + 1)

(11)


1198841015840(119896 + 2)

=

119873minus3sum


+ 1198821015840(119896 + 2)

(12)


11988410158401015840(119896) =

13[1198841015840(119896) minus 119884

1015840(119896 + 1) minus 119884

1015840(119896 + 2)]

=1


+

119873minus3

sum

119905=03

119905 =119896



(13)




(14)




119909119899= radic

2119873

119873minus1sum

119905=0120573119905119889119905cos(120587119905 (2119899 + 1)

2119873) (15)




120573119905=

1radic2

119905 = 0

1 119905 = 1 2 119873 minus 1(16)


119910119899= 119909119899cos(2120587119899120576

119873) + 119908 (119899) (17)


119910119896= radic

2119873120573119896

119873minus1sum

119899=0119910119899cos(120587119896 (2119899 + 1)

2119873) (18)

where

120573119896=

1radic2

119896 = 0

1 119896 = 1 2 119873 minus 1(19)


119910119896= 119889119896120573119896119878119896119896

+

119873minus1sum

119905=0119905 =119896119889119905120573119905119878119905119896

+119882(119896) (20)




119878119905119896

=12119873

120573119896

sdot

119873minus1sum

119899=0cos(120587 (119886119887 + 119889)

2119873) + cos(120587 (119886119888 + 119889)

2119873)

+ cos(120587 (119886119887 minus 119889)

2119873) + cos(120587 (119886119888 minus 119889)

2119873)

(21)

119886 = 2119899 + 1

119887 = 119905 + 119896

119888 = 119905 minus 119896

119889 = 4119899120576

(22)

0

50

100

150

200

250

FFT OFDM Proposed

CIR

(dB)

minus500 005 015 025 035 045


ICI SCDCT OFDM



CIRDCT =

119864 [|119862 (119896)|2]

119864 [|ICI (119896)|2]=

10038161003816100381610038161198781198961198961003816100381610038161003816

2

sum119873minus1119905=0119905 =119896

10038161003816100381610038161198781199051198961003816100381610038161003816

2 (23)




8 Conclusion







(dB)01 151044 326236 367266 125412402 86474 257274 295058 113045103 46120 211125 243512 1059674





(dB)003 265240 441881 483871 525000004 236921 413454 455374 468288005 215560 391950 433778 425466007 184010 360016 401591 362092009 160756 336250 377484 315205015 113572 286844 326523 218958030 46120 211125 243512 70959

0

20

40

60

80

100

120

CIR

(dB)

minus20

FFT OFDM Proposed


04030201

ICI SCDCT OFDM






Acknowledgments


References



































Volume 2014




Journal of











Journal of


Function Spaces






Algebra












119909119899= radic

2119873

119873minus1sum

119905=0120573119905119889119905cos(120587119905 (2119899 + 1)

2119873) (15)




120573119905=

1radic2

119905 = 0

1 119905 = 1 2 119873 minus 1(16)


119910119899= 119909119899cos(2120587119899120576

119873) + 119908 (119899) (17)


119910119896= radic

2119873120573119896

119873minus1sum

119899=0119910119899cos(120587119896 (2119899 + 1)

2119873) (18)

where

120573119896=

1radic2

119896 = 0

1 119896 = 1 2 119873 minus 1(19)


119910119896= 119889119896120573119896119878119896119896

+

119873minus1sum

119905=0119905 =119896119889119905120573119905119878119905119896

+119882(119896) (20)




119878119905119896

=12119873

120573119896

sdot

119873minus1sum

119899=0cos(120587 (119886119887 + 119889)

2119873) + cos(120587 (119886119888 + 119889)

2119873)

+ cos(120587 (119886119887 minus 119889)

2119873) + cos(120587 (119886119888 minus 119889)

2119873)

(21)

119886 = 2119899 + 1

119887 = 119905 + 119896

119888 = 119905 minus 119896

119889 = 4119899120576

(22)

0

50

100

150

200

250

FFT OFDM Proposed

CIR

(dB)

minus500 005 015 025 035 045


ICI SCDCT OFDM



CIRDCT =

119864 [|119862 (119896)|2]

119864 [|ICI (119896)|2]=

10038161003816100381610038161198781198961198961003816100381610038161003816

2

sum119873minus1119905=0119905 =119896

10038161003816100381610038161198781199051198961003816100381610038161003816

2 (23)




8 Conclusion







(dB)01 151044 326236 367266 125412402 86474 257274 295058 113045103 46120 211125 243512 1059674





(dB)003 265240 441881 483871 525000004 236921 413454 455374 468288005 215560 391950 433778 425466007 184010 360016 401591 362092009 160756 336250 377484 315205015 113572 286844 326523 218958030 46120 211125 243512 70959

0

20

40

60

80

100

120

CIR

(dB)

minus20

FFT OFDM Proposed


04030201

ICI SCDCT OFDM






Acknowledgments


References



































Volume 2014




Journal of











Journal of


Function Spaces






Algebra














(dB)01 151044 326236 367266 125412402 86474 257274 295058 113045103 46120 211125 243512 1059674





(dB)003 265240 441881 483871 525000004 236921 413454 455374 468288005 215560 391950 433778 425466007 184010 360016 401591 362092009 160756 336250 377484 315205015 113572 286844 326523 218958030 46120 211125 243512 70959

0

20

40

60

80

100

120

CIR

(dB)

minus20

FFT OFDM Proposed


04030201

ICI SCDCT OFDM






Acknowledgments


References



































Volume 2014




Journal of











Journal of


Function Spaces






Algebra



































Volume 2014




Journal of











Journal of


Function Spaces






Algebra
















Volume 2014




Journal of











Journal of


Function Spaces






Algebra









Documents

Research Article Performance on ICI Self-Cancellation in ...downloads.hindawi.com/journals/jfs/2015/854753.pdf · In OFDM system, a er IFFT the transmitted signal can be expressed