Nondata-Aided Channel Estimation for OFDM Systems With Space-Frequency Transmit Diversity

Çırpan, Hakan Ali; Panayırcı, Erdal; Doğan, Hakan

doi:10.1109/tvt.2005.863427

Cited by 33 publications

(6 citation statements)

References 21 publications

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“…The problem of interest is to derive an iterative algorithm based on the SAGE algorithm for data detection and channel estimation jointly employing the signal model given by (2). The SAGE algorithm, a generalized form of the EM algorithm [4], allows a more flexible optimization scheme and sometimes converges faster than the EM algorithm.…”

Section: Joint Data Detection and Channel Estimationmentioning

confidence: 99%

“…The SAGE algorithm is a broadly applicable approach to the iterative computation of parameters from intractable and high complexity likelihood functions. An EM approach proposed for the superimposed signals [1] is applied to the channel estimation for OFDM systems [2], [3] and compared with SAGE version in [4]. As will be seen shortly, a partial parallel interference cancelation (PIC) is incorporated into the resulting detection algorithm [5], [6].…”

Section: Introductionmentioning

confidence: 99%

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An Efficient Joint Data Detection and Channel Estimation Technique for Uplink MC-CDMA Systems Based on SAGE Algorithm

Panayırcı

Doğan

Çırpan

et al. 2007

2007 16th IST Mobile and Wireless Communications Summit

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This paper is concerned with joint channel estimation and data detection for uplink multicarrier code-division multiple-access (MC-CDMA) systems in the presence of frequency fading channel. The detection and estimation algorithm, implemented at the receiver, is based on a version of the expectation maximization (EM) technique, called the spece-alternating-generalized-expectation-maximization (SAGE) algorithm which is very suitable for the the multicarrier signal formats. Application of the SAGE algorithm to the problem of iterative data detection and channel estimation leads to a receiver structure that also incorporates a partial interference cancelation. Computer simulations show that the proposed algorithm has excellent BER end estimation performance.Index Terms: Joint data detection and channel estimation, MC-CDMA Systems, SAGE algorithm. I. INTRODUCTIONIn this paper we consider an efficient iterative algorithm based on the SAGE technique for multi-user data detection and channel estimation, jointly for uplink MC-CDMA systems in the presence of frequency selective fading channels. The SAGE algorithm is a broadly applicable approach to the iterative computation of parameters from intractable and high complexity likelihood functions. An EM approach proposed for the superimposed signals [1] is applied to the channel estimation for OFDM systems [2], [3] and compared with SAGE version in [4]. As will be seen shortly, a partial parallel interference cancelation (PIC) is incorporated into the resulting detection algorithm [5], [6]. The work is an extension of [7] in which joint data detection and channel estimation of uplink DS-CDMA systems were considered in the presence of flat Rayleigh channels. We extend their results for the uplink MC-CDMA systems with frequency selective channels. The channel estimation becomes more challenging for uplink systems since each channel between every user and the base station must be estimated rather than estimating a single channel in case of a downlink transmission.Notation: Vectors (matrices) are denoted by boldface lower (upper) case letters; all vectors are column vectors; (.) * , (.) T and (.) H denote the conjugate, transpose and conjugate transpose, respectively; . denotes the Frobenius norm; I L denotes the L × L identity matrix; diag{.} denotes a diagonal matrix; and finally, tr{.} denotes the trace of a matrix.

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Section: Joint Data Detection and Channel Estimationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An Efficient Joint Data Detection and Channel Estimation Technique for Uplink MC-CDMA Systems Based on SAGE Algorithm

Panayırcı

Doğan

Çırpan

et al. 2007

2007 16th IST Mobile and Wireless Communications Summit

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“…For ST block codes, orthogonal pilots can be employed at the transmitter and used at the receiver to estimate the channel 5, 6. Blind channel estimation techniques have also been successfully applied for ST codes 7–9. However, they are very sensitive to time‐selective communication channels.…”

Section: Introductionmentioning

confidence: 99%

MAP channel estimation with turbo processing for orthogonal space–time block coded MISO systems

Kammoun¹,

Siala

2011

Trans Emerging Tel Tech

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In this paper, we investigate fast time‐varying channel estimation for two orthogonal space–time block‐coded systems with either two or three transmit antennas and with one receive antenna. We propose an iterative expectation–maximisation‐based maximum a posteriori (MAP) semi‐blind algorithm for the estimation of the discrete propagation channels seen from the transmit antennas. This algorithm requires a convenient representation of the channel using a discrete version of the Karhunen‐Loève expansion theorem. It incorporates the coded structure of each block in a turbo‐processing fashion and uses the MAP training‐based channel estimation algorithm for its optimum initialisation. The transmit antennas are assumed to be spatially correlated for the system with two transmit antennas and spatially uncorrelated for the three‐antenna system. The validity of the proposed algorithm is highlighted by simulation results. The performance of the proposed receivers, based on MAP channel estimation, for the two systems approaches that of the perfect channel state information receiver, even for very time selective fading channels. Copyright © 2011 John Wiley & Sons, Ltd.

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“…Semi-blind channel estimation methods can enhance system performance by exploiting the unknown data symbols in addition to few pilots (usually one or two used for algorithm initialization) in the channel estimation process [2], [3], [4], [5]. An efficient and extensively-used method for semi-blind channel estimation is that based on the expectation-maximization (EM) algorithm.…”

Section: Introductionmentioning

confidence: 99%

Robust iterative receiver design under imperfect channel estimation

Sadough

2010

2010 Wireless Advanced 2010

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In a recent contribution, assuming pilot-only based channel estimation, we proposed an improved receiver which reduces the impact of channel uncertainty on the decoder performance. Here, we focus on semi-blind channel estimation based on expectation-maximization (EM) algorithm and propose an improved receiver design by an appropriate use of the channel estimation error statistics. This is done by means of an equivalent formulation of the EM algorithm from which we extract the statistics of the estimation errors. This additional soft information is used at each iteration of the receiver in a Bayesian framework to improve the performance of iterative detection. Our approach is compared to the conventional EM algorithm where the channel estimation error statistics are not available and where the receiver uses the channel estimate as if it was the perfect channel (also known as mismatched detection). Numerical results in the context of orthogonal frequency-division multiplexing show that the proposed approach outperforms the classically-used EM algorithm in terms of bit error rates.978-1-4244-7071-6/10/$26.00 2010 IEEE ©

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Nondata-Aided Channel Estimation for OFDM Systems With Space-Frequency Transmit Diversity

Cited by 33 publications

References 21 publications

An Efficient Joint Data Detection and Channel Estimation Technique for Uplink MC-CDMA Systems Based on SAGE Algorithm

An Efficient Joint Data Detection and Channel Estimation Technique for Uplink MC-CDMA Systems Based on SAGE Algorithm

MAP channel estimation with turbo processing for orthogonal space–time block coded MISO systems

Robust iterative receiver design under imperfect channel estimation

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