Iterative frequency domain channel estimation for dft-precoded ofdm systems using in-band pilots

Lam, Chan‐Tong; Falconer, D.D.; Danilo-Lemoine, F.

doi:10.1109/jsac.2008.080211

Cited by 42 publications

(11 citation statements)

References 30 publications

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“…2) Iterative CE based on combination of known pilot signals and the current soft estimates of data signals: To find the raw estimates of the channel, we use the frequency replacement method in [14]. Specifically, forΛ j SD (k) at pilot positions…”

Section: Receiver Structurementioning

confidence: 99%

Iterative frequency-domain channel estimation and equalization for single-carrier cooperative transmissions

Zhang

2012

2012 IEEE 23rd International Symposium on Personal, Indoor and Mobile Radio Communications - (PIMRC)

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Cooperative diversity is an effective transmission technique allowing multiple users to create a virtual antenna array although each of them is equipped with single antenna. In this paper, an iterative channel estimation and equalization (ICEE) scheme for single-carrier transmissions is proposed, realizing space-time block code (STBC) with amplify-and-forward (AF) relaying in a distributed fashion. Most existing researchers assume perfect channel information available at the receiver, however, the effect of imperfect channel estimation should be considered for practical applications. In the proposed algorithm, pilotaided channel estimation (CE) and soft inter-symbol interference (ISI) cancelation with minimum mean squared error (MMSE) filtering are performed iteratively to suppress interferences. An implementation that accounts for imperfect channel estimation is also investigated. The bit error rate (BER) performances and extrinsic information transfer (EXIT) charts are presented for Rayleigh fading channels. Simulation results demonstrate the effectiveness of the proposed algorithm.

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Section: Receiver Structurementioning

confidence: 99%

Iterative frequency-domain channel estimation and equalization for single-carrier cooperative transmissions

Zhang

2012

2012 IEEE 23rd International Symposium on Personal, Indoor and Mobile Radio Communications - (PIMRC)

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“…If they are stuck on a local minima, then the resulting channel estimate is poor. To remedy this problem, iterative ML and MMSE estimators (12) and (16) may be applied after running the gradient descent algorithm. From simulation, we find that usually one iteration is enough to achieve the Cramér--Rao bound.…”

Section: Is a Quadratic Form And If φ(S)mentioning

confidence: 99%

OFDM channel estimation and data detection with superimposed pilots

Cui

Tellambura

2011

Trans Emerging Tel Tech

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We propose three iterative superimposed-pilot based channel estimators for Orthogonal Frequency Division Multiplexing (OFDM) systems. Two are approximate maximum-likelihood, derived by using a Taylor expansion of the conditional probability density function of the received signal or by approximating the OFDM time signal as Gaussian, and one is minimum-mean square error. The complexity per iteration of these estimators is given by approximately O(NL 2 ), O(N 3 ) and O (NL), where N is the number of OFDM subcarriers and L is the channel length (time). Two direct (non-iterative) data detectors are also derived by averaging the log likelihood function over the channel statistics. These detectors require minimising the cost metric in an integer space, and we suggest the use of the sphere decoder for them. The Cramér--Rao bound for superimposed pilot based channel estimation is derived, and this bound is achieved by the proposed estimators. The optimal pilot placement is shown to be the equally spaced distribution of pilots. The bit error rate of the proposed estimators is simulated for N = 32 OFDM system. Our estimators perform fairly close to a separated training scheme, but without any loss of spectral efficiency.

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“…The drawback of this method is that it results in nulls in the equivalent channel impulse response (seen by data symbols), and hence, in a performance degradation. This degradation could be reduced by performing iterative channel equalization Lam et al (2008). On the other hand, such a scheme leads to increased envelope fluctuations of the transmitted signal.…”

Section: Data-dependent Overlay Pilotsmentioning

confidence: 99%