Analysis of OFDM in the presence of frequency offset and a method to reduce performance degradation

Sathananthan, K.; Rajatheva, R.M.A.P.; Slimane, S.B.

doi:10.1109/glocom.2000.891691

Cited by 32 publications

(27 citation statements)

References 6 publications

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“…When symbol is change to next symbol the phase of the carrier changed by 45º (π/4 radians). The table (1) shows symbol and their phase shifts [7]. Therefore if a complex data pair ex:(a,-a) is modulated onto two symmetrically placed subcarriers ,then the ICI generated by these subcarrier will be significantly cancelled out.…”

Section: Standard Ofdm Systemmentioning

confidence: 99%

A Novel methods of ICI self Cancellation Scheme in OFDM System

2014

IJRA

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In OFDM System the Frequency offset in wireless communication systems distort the Orthogonality between subcarriers resulting in Inter Carrier Interference(ICI).This Paper presents a new scheme for ICI self cancellation which is simple and convenient technique. It utilize data allocation and combining of ( , so  so  ) on to a pair of symmetrically placed subcarriers to reduce the ICI. In proposed scheme we are maximizing CIR performance for a normal frequency offset  . In this method the CIR performance is about more than 20dB better than that of normal OFDM for Small values of frequency offset  and having same bandwidth efficiency for larger Doppler frequency. Simulation results show that comparing proposed scheme with standard OFDM system and conventional ICI self cancellation. In simulation results we found that the performance of proposed scheme is better than the standard OFDM system and conventional ICI self cancellation.

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Section: Standard Ofdm Systemmentioning

confidence: 99%

A Novel methods of ICI self Cancellation Scheme in OFDM System

2014

IJRA

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“…In this scheme the data symbols are repeated on multiple adjacent subcarriers using polynomial coding but it results in PAPR performance degradation. The CIR performance of ICI self cancellation can be further improved by the scheme [17] proposed by Santhananthan et al and called "New ICI self-cancellation scheme". In this scheme [17] data symbols are repeated symmetrically using polynomial coding, which achieves frequency diversity effect of multipath fading channel.…”

Section: Related Workmentioning

confidence: 99%

“…In this scheme [17] data symbols are repeated symmetrically using polynomial coding, which achieves frequency diversity effect of multipath fading channel. The CIR and the BER performance of ICI cancellation schemes [16], [17] are claimed to be further improved by General ICI cancellation scheme, proposed by Seyedi et al, which is based on windowing technique used at the transmitter and receiver of OFDM system.…”

Section: Related Workmentioning

confidence: 99%

Review on PAPR Reduction in OFDM based system

Narula¹

2015

IJIRSET

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ABSTRACT:In recent time, the demand for multimedia data services has grown up rapidly. One of the most promising multi-carrier system, Orthogonal Frequency Division Multiplexing (OFDM) forms basis for all 4G wireless communication systems due to its large capacity to allow the number of subcarriers, high data rate and ubiquitous coverage with high mobility. OFDM is significantly affected by peak-to-average-power ratio (PAPR). Unfortunately, the high PAPR inherent to OFDM signal envelopes will occasionally drive high power amplifiers (HPAs) to operate in the nonlinear region of their characteristic curve. The nonlinearity of the HPA exhibits amplitude and phase distortions, which cause loss of orthogonality among the subcarriers, and hence, inter-carrier interference (ICI) is introduced in the transmitted signal. Not only that, high PAPR also leads to in-band distortion and out-of-band radiation. Different techniques are used to reduce the Peak to Average Power Ratio (PAPR) to increase the efficiency of the OFDM system. In this paper some of these important techniques are reviewed.

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“…This method proposed by Sathanantham, Rajatheva and Slimane, which utilizes data allocation and combining of (1,-1) at k th and (N-1-k) th subcarrier [7]. This scheme shows better CIR performance than ICI self cancellation scheme.…”

Section: Symmetric Symbol Repeat Ici Self Cancellationmentioning

confidence: 99%

Mitigation of ICI Through Optimized SSR ICI Self Cancellation Scheme in OFDM

Kongonda¹,

Tadishetty²

2016

ijcert

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Abstract:Orthogonal frequency division multiplexing (OFDM) is extensively used in wireless communication systems because it offers high data rates and provides a better solution to inter symbol interference (ISI) caused by a multipath channel. A well known problem of OFDM system is sensitive to carrier frequency offset (δ) between the transmitted and received signals. The Frequency offset in wireless communication systems ruins the Orthogonality between subcarriers resulting in Inter Carrier Interference (ICI).Which is a severe problem in OFDM system and eventually decrease the performance of the system. There are numerous techniques are in existence to mitigate the effect of ICI caused by CFO (carrier frequency offset). This paper investigates an innovative ICI cancellation method termed as optimized SSR (symmetric symbol repeat) ICI self cancellation scheme. The proposed method utilizes an optimum data allocation (1,-λ) and combining (1,-µ) scheme to improve CIR performance for an estimated normalized frequency offset δ. However, this requires continuous CFO estimation and feedback circuitry. To avoid the requirement of CFO, sub optimal values (λso, µso) are considered for combating the effect of ICI. This paper mainly focus on comparison of proposed method with the previous reduction methods and standard OFDM system in terms of CIR (carrier to interference) & BER (bit error rate) performance. Keywords: OFDM, ICI, ISI, CFO, CIR, BER, QAM I.INTRODUCTIONIn Today's world OFDM plays vital role in wireless communication systems, which is a promising modulating technique for high data rate transmission in wireless communication [1] systems. OFDM is a form of multi-carrier modulation technique [2], which effectively utilizes the spectrum by spacing the channels much closer together. This spectral efficiency can be achieved by making orthogonality between the sub carriers and preventing interference between the subcarriers. In OFDM, a high-rate data stream is divided into many lowerrate streams which are mapped (by using QAM or QPSK) onto mutually overlapping subcarriers and transmitted simultaneously i.e., high rate bit stream is split into N parallel lower rate bit streams and each of these streams are modulated using one of N orthogonal sub-carriers. However, OFDM is being widely used in many applications such as IEEE 802.11a, the multimedia mobile access communication (MMAC), HIPER-LAN/2, Digital Video Broadcasting (DVB) and so on.. In a basic communication system, the input data is modulated using only one carrier frequency. Therefore the available channel bandwidth is totally occupied by each symbol. This type of mechanism can lead to inter symbol-interference (ISI) in frequency selective channels.By inserting Guard interval with the cyclic extension of the OFDM symbol, the inter symbol interference (ISI) can be easily avoided. A well known problem with OFDM is its vulnerability to slight differences in frequency at the transmitter and receiver, normally referred as frequency offset, caused by Doppler shift due ...

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Analysis of OFDM in the presence of frequency offset and a method to reduce performance degradation

Cited by 32 publications

References 6 publications

A Novel methods of ICI self Cancellation Scheme in OFDM System

A Novel methods of ICI self Cancellation Scheme in OFDM System

Review on PAPR Reduction in OFDM based system

Mitigation of ICI Through Optimized SSR ICI Self Cancellation Scheme in OFDM

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