OFDM error floor based EVM estimation

Lipovac, Adriana; Modlic, Borivoj; Grgić, Mislav

doi:10.1109/softcom.2016.7772163

Cited by 9 publications

(7 citation statements)

References 3 publications

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“…Specifically, the LTE lab with the state-of-the-art vector signal analysis (VSA) and Error Vector Magnitude (EVM) measurements [16] is the best solution for the analysis with this regard [17][18].…”

Section: Testing Papr Reductionmentioning

confidence: 99%

“…However, when the maximal-amplitude symbols enter into the negative-back-off zone, then, as already mentioned above, the HPA non-linear distortion occurs, usually expressed as the peak normalized EVM for the largest symbol amplitudes, relative to the ideal (reference) k-th symbol power [17]: (3)…”

Section: A Ber Based Papr Estimationmentioning

confidence: 99%

“…Here we consider BER as being determined just by HPA distortion, as strong signal implies large SNR, while also no time dispersion (and so no multipath fading and the consequent inter-symbol interference) is present due to long enough cyclic prefix. Now we recall the relationship between the EVM and the HPA-distortion determined BER [17]:…”

Section: A Ber Based Papr Estimationmentioning

confidence: 99%

“…On the other hand, more realistic PAPR values are obtained by accordingly modifying (17) to take into account not only the (rarely appearing) 64-QAM highest-amplitude symbols, but all maximal amplitudes' values from ( 16), weighted by their probabilities of occurrence in the OFDM symbol, which can take various values, such as e.g. [19]:…”

Section: A Verification Of Papr Estimationmentioning

confidence: 99%

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In-Service BER Based Estimation of OFDM PAPR and CFO-induced Peak Phase Deviation

Lipovac

Mihaljević

2019

JCOMSS

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Section: Testing Papr Reductionmentioning

confidence: 99%

Section: A Ber Based Papr Estimationmentioning

confidence: 99%

Section: A Ber Based Papr Estimationmentioning

confidence: 99%

Section: A Verification Of Papr Estimationmentioning

confidence: 99%

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In-Service BER Based Estimation of OFDM PAPR and CFO-induced Peak Phase Deviation

Lipovac

Mihaljević

2019

JCOMSS

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“…Furthermore, back to basics, the well-known BER expression for the Quadrature Amplitude Modulation (QAM) signal transmission over the additive white Gaussian noise (AWGN) channel with E b /N 0 ratio of the energy E b of a bit and noise spectral density N 0 is [13]:…”

Section: Introductionmentioning

confidence: 99%

Practical BER-Based Estimation of Residual OFDM CFO by Reducing Noise Margin

Mihaljević

Lipovac

et al. 2020

Wireless Communications and Mobile Computing

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The main OFDM drawbacks are Carrier Frequency Offset (CFO) and large Peak-to-Average Power Ratio (PAPR), which both degrade the Bit Error Rate (BER). Specifically, we consider here clipping or any other PAPR reduction method sufficient to prevent the nonlinear high-power amplifier from generating errors. Moreover, in small cells, the signal-to-noise ratio is large, while the small time dispersion allows the OFDM symbol cyclic prefix to prevent intersymbol interference. This retains the CFO to solely determine the BER and vice versa, enabling indirect estimation of CFO-induced phase distortion by simple BER testing. However, a particular problem is measuring very low BER values (generated by alike residual CFO), which could last a long time in order to acquire statistically enough errors. The test time can be drastically reduced if the noise margin is reduced in a controllable way, by adding the interfering signal to each subcarrier at the receiver. This approach is shown to enable efficient and accurate short-term BER (and so CFO phase error) testing.

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Closed-Form Enhanced Detection of Clipped OFDM Symbol

Lipovac,

Mihaljević,

Lipovac

2024

IEEE Access

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Large peak-to-average power ratio (PAPR) and carrier frequency offset (CFO) are dominant impairments of the orthogonal frequency-division multiplexing (OFDM) symbol transmission that is applied within the state-of-the-art wireless operator networks. In this work, we deal with consequences of the amplitude peak clipping that is commonly used at the transmitter to reduce the PAPR of the OFDM symbol, and thus prevent its non-linear distortion which would otherwise be imposed by the output highpower amplifier (HPA). Accordingly, regardless of the clipping generating mechanism at the transmitter being either inherent (related to the HPA) or deliberate (due to PAPR reduction), the clipped incoming OFDM symbol at the receiver may lead to degraded detection accuracy and transmission performance. However, the methods that have been applied so far at the receiver for compensating non-linear distortion due to clipping, are quite complex and computationally demanding. On the contrary, we propose effective mitigation of the problem to be performed at the receiver, by deriving the closed-form enhanced detection criterion, which requires common measurements of the mean and the rms values, as well as the autocorrelation of the received OFDM symbol comprising both un-clipped and clipped sections. Such improved detection was shown to significantly reduce the side effects of clipping, and restore satisfactory transmission performance -the bit error rate (BER) in particular. The proposed analytical model was preliminarily verified by versatile Monte-Carlo simulations and professional industry-standard vector signal analysis (VSA) test system, as well as by BER testing. The evident convergence of the three methods' test results leads to the conclusion that the proposed clipped OFDM symbol detection method provides clear improvement with respect to the conventional one.

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OFDM error floor based EVM estimation

Cited by 9 publications

References 3 publications

In-Service BER Based Estimation of OFDM PAPR and CFO-induced Peak Phase Deviation

In-Service BER Based Estimation of OFDM PAPR and CFO-induced Peak Phase Deviation

Practical BER-Based Estimation of Residual OFDM CFO by Reducing Noise Margin

Closed-Form Enhanced Detection of Clipped OFDM Symbol

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