Iterative data detection and channel estimation for advanced TDMA systems

Abstract

This letter presents a new receiver for-ary transmission, where all receiver blocks are embedded in an iterative structure. Packet data transmission in global systems for mobile communications (GSM) and enhanced data rates for global evolution (EDGE) are considered as examples. A low-complexity soft-insoft-out detector for EDGE is introduced and its modification suitable for iterative detection is derived. Application of iterative detection and channel estimation techniques in GSM/EDGE shows a significant performance enhancement. Additional improvement may be obtained if the iterative processing is applied to packet retransmission schemes.

Soft-Iterative Channel Estimation: Methods and Performance Analysis

“…The estimation error (26) for the SB-LS method can be obtained from (11), (12), and (25), as (28) Recalling (25), (22), and the independence assumption for the noise vectors in (28), it can be shown by straightforward calculations that the error correlation matrix is given by (29) The corresponding MSE is shown in Table I (row 7).…”

“…By generalizing the results in [25], here we consider the maximum likelihood estimation of from the MB measurements modeled as in (11), under the Gaussian approximation for and under the channel structure constraint (3). The MB approximate maximum likelihood estimate (MB-AML) is obtained by the minimization of , with defined according to (20), constrained to (3), yielding (23) represents the estimate of the projector onto the stationary subspace spanned by the channel covariance matrix weighted by , and it is obtained from the leading eigenvectors of the sample covariance matrix (24) As in the training-based case [25], the MB-AML estimate (23) can be interpreted as a postprocessing of the whitened SB-AML estimate , so called because it has an identity matrix as covariance matrix.…”

“…Recently, several soft-iterative channel estimation methods have been developed for single-user [4]- [15] and multiuser [16]- [24] (such as CDMA, MC-CDMA) systems, with either single-antenna [4]- [13], [16]- [23] or multiple-antenna [14], [15], [24] transceivers, over frequency-flat [4]- [6], [15]- [19] or frequency-selective [7]- [14], [20]- [24] channels. Channel estimates are obtained using different criteria: the least squares (LS) criterion [8], [14], [16], [20], [21]; the minimum-mean-square-error (MMSE) method [9], [17], [18], [21], [23], [24]; the maximum a posteriori (MAP) estimation [15]; algorithms based on the expectation-maximization (EM) approach [7], [10], [19]; and adaptive methods for the estimation of time-varying channels [8], [11]- [13], [21], [22], such as least mean squares (LMS), recursive least squares (RLS), or Kalman filtering (KF).…”

A comparison analysis of prefiltering methods in space-time trellis-based reduced-state turbo-detection

“…Because the delayed decision-feedback sequence estimator (DDFSE) associated with prefiltering is shown to ensure a reasonable trade-off between performance and complexity [13-20], a modified lowcomplexity soft input soft output (SISO) DDFSEbased detector [SISO decision feedback sequence estimation (DFSE)] [21] is used for iterative ISI detection. We witness that such association (MIMO WMF with SISO DFSE) represents a good alternative to the generalized soft Viterbi algorithm [4], which compensates the error-propagation induced to the PSP by retaining more than one survivor path per state without resorting to a prefilter front-end [3,22].…”

Joint channel estimation and decoding with low-complexity iterative structures in time-varying fading channels

“…The proposed receiver employs a maximum-likelihood (ML) channel estimator using a known training sequence and a maximum-likelihood sequence estimator (MLSE) to extract the transmitted symbols. As an extension, the work in [2] considers a channel code over the same channel which is now assumed to be quasi-static. An LMS filter with hard estimates of the code symbols is used after the initial estimation iteration.…”