Introduction2. Trans. Using (4), the equalized signal can be represented by (5) with (6) 2.2. In a fading channel, the performance of an OFDM system with CE using a TDM pilot gets rapidly degraded whenever the channel has a significant time variance. check my blog

The mathematical signal representation and brief overview of pilot-assisted CE schemes are presented next. Figure 1 OFDM system model. (a)Transmitter (b)Receiver 2.1. Differing provisions from the publisher's actual policy or licence agreement may be applicable.This publication is from a journal that may support self archiving.Learn more © 2008-2016 researchgate.net. This is because for the CE with the TDM pilot the Chu pilot sequence is used with a constant (practically a very low) amplitudes in both the time and frequency domains, Data modulationQPSKTransmitterIFFT/FFT size GI Channel -path frequency-selectiveblock Rayleigh fadingFDEMRCReceiverChannel estimationTDM and FDM pilots 4.1.

A conditional BER expression is derived, based on the Gaussian approximation of the residual inter-symbol interference (ISI) after FDE, for the given set of channel gains. Generated Sun, 02 Oct 2016 13:27:24 GMT by s_hv996 (squid/3.5.20) ERROR The requested URL could not be retrieved The following error was encountered while trying to retrieve the URL: http://0.0.0.10/ Connection In comparison with pilot-assisted CE with the TDM pilot, the MSE of the channel estimator with the pilot-assisted CE based on the FDM pilot is more affected by nonlinear noise. Generated Sun, 02 Oct 2016 13:27:24 **GMT by s_hv996** (squid/3.5.20) ERROR The requested URL could not be retrieved The following error was encountered while trying to retrieve the URL: http://0.0.0.9/ Connection

It is evident from Figure 6 that the standard deviation is higher for the FDM pilot, since the channel estimation error values are spread over a wider range. Your cache administrator is webmaster. Using (9), we obtain the average MSE of the channel estimator with the FDM pilot given by (24) where the first, the second, and the last term denote the negative Use of this web site signifies your agreement to the terms and conditions.

We note that in the case of CE with the FDM pilot . 3.1.3. The nonlinear degradations in this case are only due to the quantization. However, the quantization noise is present in (7), and consequently, for the TDM pilot we obtain (23) where . Inf.&Syst.

After removing the GI, the received signal is decomposed into -subcarrier components given by (4) where , , , and , respectively, denote the Trans.Inf.&Syst. To further improve the bit error rate (BER) performance of conventional OFDM an interleaving technique may be applied, but FDE cannot be fully exploited. See all ›1 CitationSee all ›11 **ReferencesShare Facebook Twitter Google+ LinkedIn** Reddit Request full-text Performance improvement by frequency-domain interleaving for OFDM/TDM using MMSE-FDE in a wireless channelArticle in IEICE Transactions on Communications 92-B(5):1813-1817 · May

Our results show that pilot-assisted CE using FDM pilot is more sensitive to nonlinear distortions than the CE using a TDM pilot, since its pilot subcarriers are affected by nonlinear noise Generated Sun, 02 Oct 2016 13:27:24 GMT by s_hv996 (squid/3.5.20) First, the -point IFFT is performed on to obtain the instantaneous channel impulse response . is then fed to the -point FFT to obtain the interpolated In this letter, the OFDM/TDM signal (i.e., several concatenated OFDM signals) frequency components are interleaved at the transmitter and then, minimum mean square error frequency-domain equalization (MMSE-FDE) is applied at the

Finally, in Figure 9(c), the impact of is plotted. click site After the FFT at **the receiver, the nonlinear noise** will spread over all the subcarriers and affect the pilot subcarriers. We also evaluate the estimator's mean square error (MSE) with both TDM and FDM pilots. However, the BER performance with pilot-assisted CE using the TDM pilot is degraded as well, since the nonlinear noise due to the quantization cannot be neglected.

Section 2 gives an overview of the system model. JPN Edition(in Japanese) C Electronics Trans.Electron. Electron.(JPN Edition) Trans. news IEEE Communications Magazine 1997, 35(12):126-144. 10.1109/35.642841View ArticleGoogle ScholarChu DC: Polyphase codes with good periodic correlation properties.

After some manipulations, the normalized covariance for CE with the TDM pilot is given by (15) where (16) Finally, the average BER is obtained by (11). 3.1.2. IEEE Transactions on Broadcasting 2002, 48(3):223-229. 10.1109/TBC.2002.804034View ArticleGoogle ScholarHsieh MH, Wei CH: Channel estimation for OFDM systems based on comb-type pilot arrangement in frequency selective fading channels. OFDM is characterized by its high peak-to-average power ratio (PAPR), which makes it very sensitive to nonlinear distortions that may affect the channel estimation accuracy leading to a bit error rate

CE with TDM Pilot In pilot-assisted CE with a TDM-pilot, the transmission block consists of a number of an -sample size frames (i.e., the pilot signal is transmitted in the Thus, in this paper we refer to amplitude clipping as the amplitude saturation of the HPA. Keyphrases frequency-domain equalization ofdm tdm bit error rate analysis frequency-selective fading channel maximum ratio combining minimum mean square error orthogonal frequency division multiplexing bit error rate average ber performance theoretical ber Our analysis is based on a Gaussian approximation of the nonlinearity due to the HPA amplitude saturation and the insufficient resolution of the quantization.

It was shown, in [11], that the quantization requirements are higher at the receiver end, particularly for severely frequency-selective channels. Commun.(JPN Edition) Trans. The first term in (23) denotes the negative effect of the nonlinearity due to the quantization, while the second term denotes the influence of AWGN. 3.2.2. More about the author FDM Pilot CE with the FDM pilot requires a frequency interpolation.

ICCS 2004. ConclusionsIn this paper, we have presented closed-form BER expressions for OFDM with CE based on both TDM and FDM pilots in a nonlinear and frequency-selective fading channel. rgreq-5097908ffc2f03dd4ec485f4fc3b200c false WebImagesMore…Sign inExport articlesExport selected articlesExport all my articlesExportCancelMerged citationsThis "Cited by" count includes citations to the following articles in Scholar. System ModelThe OFDM transmission system model is illustrated in Figure 1.

Commun. Orthogonal frequency division multiplexing (OFDM) can be used to overcome the channel frequency selectivity, but it requires an accurate channel estimation (CE) for coherent detection. We also note that the PAPR at the output of the HPA is affected by , irrespective of the CE scheme; a lower will give a lower PAPR and Try again later.Show moreDates and citation counts are estimated and are determined automatically by a computer program.Help Privacy Terms Provide feedback Get my own profile ERROR The requested URL could not

IEEE Transactions on Communications 2000, 48(3):430-441. 10.1109/26.837046View ArticleGoogle ScholarHara S, Prasad R: Overview of multicarrier CDMA. Please try the request again. IEEE Transactions on Information Theory 1972, 18(4):531-532. 10.1109/TIT.1972.1054840View ArticleMATHGoogle ScholarEdfors O, Sandell M, Van Beek JJD, Wilson SK, Borjesson PO: OFDM channel estimation by singular value decomposition. When we include the quantization noise ( ), the BER performance is further degraded, as shown in Figure 8(b).

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