OFDM uplink for interactive broadband wireless: analysis and simulation in the presence of carrier, clock and timing errors

El-Tanany, M.; Wu, Yiyan; Hazy, L.

doi:10.1109/11.920776

Cited by 51 publications

(20 citation statements)

References 8 publications

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“…In [10] the performance in the presence of phase noise is obtained by evaluating the SNR degradation for a PSK modulation with different receiver schemes. In [11] a similar approach is carried out to evaluate the SIR, in the presence of frequency and timing errors. Also in more recent works, dealing especially with the determination of efficient compensation schemes, [12][13][14], the approach more commonly used is to determine the signal to interference plus noise ratio (SINR).…”

Section: Introductionmentioning

confidence: 99%

“…OFDM systems exhibit a higher sensitivity to phase noise than single carrier modulations and to reduce its effects only a partial compensation based on pilot symbols can be employed [4,5]. In the literature the problem of phase noise in OFDM systems has been considered in many works [6][7][8][9][10][11][12][13][14]. In [6] the SNR degradation is evaluated with a frequency offset in the carrier synchronization and phase noise, considering an integrate-and-dump filtering over the symbol period.…”

Section: Introductionmentioning

confidence: 99%

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Phase Noise Spectral Limits in OFDM Systems

Corvaja

Pupolin

2006

Wireless Pers Commun

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OFDM is recognized to be one of the best transmission techniques for wideband wireless communication systems. However, it exhibits two main drawbacks: its large amplitude fluctuation and its sensitivity to phase noise. Here we consider the phase noise impairments, taking care of the phase noise spectrum, which diverges form the classical Wiener model as the carrier frequency increases. Moreover, we show that the phase noise distortion can be decomposed in two terms, one dependent on the symbol under detection and the other dependent on the symbols of adjacent subcarriers, so that the performance degradation depends on both the constellation used in each subcarrier and the phase noise spectrum. As a consequence of this new results, the penalty due to phase noise expressed in terms of the average signal/noise plus interference ratio is not applicable in the case of modulations with non-constant amplitude constellations, such as 16-or 64-QAM. The method proposed here achieves a good accuracy, while keeping a low computational complexity, and it is confirmed by simulations.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phase Noise Spectral Limits in OFDM Systems

Corvaja

Pupolin

2006

Wireless Pers Commun

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“…, M}. This index scheme is shown in Most of the 2M subcarriers are used for data modulation, some of them can be used as pilots for channel estimation, and some of them can be used as null subcarriers as proposed in [25]- [27]. Without loss of generality, the 2M available subcarriers are not differentiated in this paper, since the usage of a subcarrier can be inferred from its modulation symbol.…”

Section: A Multiple Access In Ofdmamentioning

confidence: 99%

Low-Complexity Orthogonal Spectral Signal Construction for Generalized OFDMA Uplink With Frequency Synchronization Errors

Cao

Tureli

Yao

2007

IEEE Trans. Veh. Technol.

117

138

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Abstract-In orthogonal frequency-division multiplexing, the total spectral resource is partitioned into multiple orthogonal subcarriers. These subcarriers are assigned to different users for simultaneous transmission in orthogonal frequency-division multiple access (OFDMA). In an unsynchronized OFDMA uplink, each user has a different carrier frequency offset (CFO) relative to the common uplink receiver, which results in the loss of orthogonality among subcarriers and thereby multiple access interference. Hence, OFDMA is very sensitive to frequency synchronization errors. In this paper, we construct the received signals in frequency domain that would have been received if all users were frequency synchronized. A generalized OFDMA framework for arbitrary subcarrier assignments is proposed. The interference in the generalized OFDMA uplink due to frequency synchronization errors is characterized in a multiuser signal model. Least squares and minimum mean square error criteria are proposed to construct the orthogonal spectral signals from one OFDMA block contaminated with interference that was caused by the CFOs of multiple users. For OFDMA with a large number of subcarriers, a low-complexity implementation of the proposed algorithms is developed based on a banded matrix approximation. Numerical results illustrate that the proposed algorithms improve the system performance significantly and are computationally affordable using the banded system implementation.Index Terms-Banded matrix, carrier frequency offset (CFO), least squares (LS), minimum mean-square error (MMSE), multiple access, orthogonal frequency-division multiplexing (OFDM), synchronization.

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“…In OFDMA systems, sampling clock frequency mismatch, carrier frequency offsets (CFOs) due to poor oscillator alignments and Doppler effects, and timing delay caused by multi-path and non-ideal synchronization will seriously destroy the orthogonality among subcarriers. Moreover, they introduce the inter-carrier interference (ICI) and the multi-user interference (MUI) [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

A Low Power High-Speed 8-Bit Pipelining CLA Design Using Dual-Threshold Voltage Domino Logic

Wang

Huang

Lee

et al. 2008

IEEE Trans. VLSI Syst.

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A successive interference cancellation (SIC) structure is proposed for multi-user interference cancellation (MUI) due to carrier frequency offsets (CFOs) in the uplink of orthogonal frequency division multiple access (OFDMA) systems. The proposed architecture adopts a circular convolution to suppress the impacts caused by CFOs. This paper demonstrates that, with 2 iterations, the SIC has better performance than that of the parallel interference cancellation (PIC) structure. However, system complexity is only 1/2K, where K is the number of users in the system. This study also shows that system complexity can be significantly reduced if proper approximation is made.Keywords -Orthogonal frequency division multiple access (OFDMA), carrier frequency offset, multi-user interference (MUI), circular convolution, successive interference cancellation (SIC).

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OFDM uplink for interactive broadband wireless: analysis and simulation in the presence of carrier, clock and timing errors

Cited by 51 publications

References 8 publications

Phase Noise Spectral Limits in OFDM Systems

Phase Noise Spectral Limits in OFDM Systems

Low-Complexity Orthogonal Spectral Signal Construction for Generalized OFDMA Uplink With Frequency Synchronization Errors

A Low Power High-Speed 8-Bit Pipelining CLA Design Using Dual-Threshold Voltage Domino Logic

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