Results 1  10
of
22
PerSurvivor Processing: a General Approach to MLSE in Uncertain Environments,”
 IEEE Trans. Commun.,
, 1995
"... ..."
(Show Context)
The structure and design of realizable decision feedback equalizers for IIR channels with coloured noise
, 1990
"... A simple algorithm for optimizing decision feedback equalizers by minimizing the mean square error (MSE) is presented. A complex baseband channel and correct past decisions are assumed. The dispersive channel may have infinite impulse response and the noise may be coloured. We consider optimal reali ..."
Abstract

Cited by 17 (10 self)
 Add to MetaCart
A simple algorithm for optimizing decision feedback equalizers by minimizing the mean square error (MSE) is presented. A complex baseband channel and correct past decisions are assumed. The dispersive channel may have infinite impulse response and the noise may be coloured. We consider optimal realizable (stable and finitelag smoothing) forward and feedback filters in discrete time. They are parametrized as recursive filters. In the special case of transmission channels with finite impulse response and autoregressive noise, the minimum MSE can be attained with transversal feedback and forward filters. In general, the forward part should include a noisewhitening filter (the inverse noise model). The finite realizations of the filters are calculated using a polynomial equation approach to the linear quadratic optimization problem. The equalizer is optimized essentially by solving a system of linear equations Ax = B, where A contains transfer function coefficients from the channel and ...
Continuous Error Detection (CED) for reliable communication.
, 2001
"... Block Cyclic Redundancy Check (CRC) codes represent a popular and powerful class of error detection techniques used almost exclusively in modern data communication systems. Though efficient, CRCs can detect errors only after an entire block of data has been received and processed. In this work, we p ..."
Abstract

Cited by 8 (0 self)
 Add to MetaCart
Block Cyclic Redundancy Check (CRC) codes represent a popular and powerful class of error detection techniques used almost exclusively in modern data communication systems. Though efficient, CRCs can detect errors only after an entire block of data has been received and processed. In this work, we propose a new "continuous" error detection (CED) scheme using arithmetic coding that provides a novel tradeoff between the amount of added redundancy and the amount of time needed to detect an error once it occurs. We demonstrate how the new error detection framework improves the overall performance of transmission systems, and show how sizeable performance gains can be attained. We focus on several important scenarios: (i) Automatic Repeat ReQuest (ARQ) based transmission; (ii) Forward Error Correction (FEC) frameworks based on (serially) concatenated coding systems involving an inner errorcorrection code and an outer errordetection code; and (iii) Reduced State Sequence Estimation (RSSE) ...
A Novel ReducedComplexity MAP Equalizer Using SoftStatistics for DecisionFeedback ISI Cancellation
 ISI Cancellation”, IEEE Globecom Conference, Rio de Janeiro
, 1999
"... A novel version of the reducedstate Bayesian Maximum A Posteriori Probability /DecisionFeedback (MAP/DF) equalizer for ISI channels with long impulse responses is presented. The main feature of the proposed equalizer is that the softstatistics generated by the MAP receiver are employed to recursi ..."
Abstract

Cited by 5 (3 self)
 Add to MetaCart
A novel version of the reducedstate Bayesian Maximum A Posteriori Probability /DecisionFeedback (MAP/DF) equalizer for ISI channels with long impulse responses is presented. The main feature of the proposed equalizer is that the softstatistics generated by the MAP receiver are employed to recursively compute a suitable index of the actual reliability of the (soft) decisions feeding the DF filter. Therefore, in the presented equalizer the usual (overoptimistic) assumption of errorfree decisions at the input of the feedback filter is relaxed and numerical results supporting the actual effectiveness of the proposed MAP/DF equalizer are provided for the socalled HighBitRate Digital Subscriber Line (HDSL) testloop # 4.
Reduced Complexity SuperTrellis Decoding for Convolutionally Encoded Transmission Over ISIChannels
"... Abstract—In this paper we propose a matched encoding (ME) scheme for convolutionally encoded transmission over intersymbol interference (usually called ISI) channels. A novel trellis description enables to perform equalization and decoding jointly, i.e., enables efficient supertrellis decoding. By ..."
Abstract

Cited by 4 (4 self)
 Add to MetaCart
(Show Context)
Abstract—In this paper we propose a matched encoding (ME) scheme for convolutionally encoded transmission over intersymbol interference (usually called ISI) channels. A novel trellis description enables to perform equalization and decoding jointly, i.e., enables efficient supertrellis decoding. By means of this matched nonlinear trellis description we can significantly reduce the number of states needed for the receiverside Viterbi algorithm to perform maximumlikelihood sequence estimation. Further complexity reduction is achieved using the concept of reducedstate sequence estimation. Index Terms—ISIchannel; convolutionally encoded transmission; supertrellis decoding; matched decoding; reduced state sequence estimation; trelliscoded modulation; I.
Low Complexity MLSE Equalization in Highly Dispersive Rayleigh Fading Channels
, 2010
"... A soft output low complexity maximum likelihood sequence estimation (MLSE) equalizer is proposed to equalize MQAM signals in systems with extremely long memory. The computational complexity of the proposed equalizer is quadratic in the data block length and approximately independent of the channel ..."
Abstract

Cited by 3 (2 self)
 Add to MetaCart
A soft output low complexity maximum likelihood sequence estimation (MLSE) equalizer is proposed to equalize MQAM signals in systems with extremely long memory. The computational complexity of the proposed equalizer is quadratic in the data block length and approximately independent of the channel memory length, due to high parallelism of its underlying Hopfield neural network structure. The superior complexity of the proposed equalizer allows it to equalize signals with hundreds of memory elements at a fraction of the computational cost of conventional optimal equalizer, which has complexity linear in the data block length but exponential in die channel memory length. The proposed equalizer is evaluated in extremely long sparse and dense Rayleigh fading channels for uncoded BPSK and 16QAMmodulated systems and remarkable performance gains are achieved.
Mitigation Of Error Propagation In Decision Feedback Equalization
, 1999
"... A major obstacle to reliable digital communication is intersymbol interference (ISI) and noise, encountered in transmission over dispersive channels. Thus, equalization of the channel at the receiver is necessary. There has been immense interest in the research community, since the early 1970s, on ..."
Abstract

Cited by 2 (0 self)
 Add to MetaCart
A major obstacle to reliable digital communication is intersymbol interference (ISI) and noise, encountered in transmission over dispersive channels. Thus, equalization of the channel at the receiver is necessary. There has been immense interest in the research community, since the early 1970s, on decision feedback equalizers (DFE) which are very effective and relatively easy to implement. Unfortunately, DFE performance is hampered by error propagation. Though this phenomenon has been known for a long time, only a modest amount of work has been done on characterizing it and very little work has been done on mitigating error propagation. The bulk of DFE research has been devoted to proposal and performance study of various modifications of the basic DFE. In this tradition, a soft decision feedback equalization scheme has been proposed in this thesis, where the hardlimiter of a conventional DFE is replaced with a soft decision device. The intention of this modification is mitigation o...
Distance Enhancing Constraints For Noise Predictive Maximum Likelihood Detectors
 in Proc. IEEE Global Telecommun. Conf
, 1998
"... Using performance analysis of Reduced State Sequence Estimators (RSSE), we characterize dominant error events for a Noise Predictive Maximum Likelihood (NPML) detector. The error event characterization may be used to determine distance enhancing constraints that improve the reliability of NPML/RSSE ..."
Abstract

Cited by 2 (0 self)
 Add to MetaCart
(Show Context)
Using performance analysis of Reduced State Sequence Estimators (RSSE), we characterize dominant error events for a Noise Predictive Maximum Likelihood (NPML) detector. The error event characterization may be used to determine distance enhancing constraints that improve the reliability of NPML/RSSE detection. An example of a constraint that provides approximately :8 dB asymptotic coding gain for an NPML detector operating at a user bit density of 2:54 is illustrated. I. Introduction Many high density magnetic recording devices employ equalization to a partial response target (PR) and maximumlikelihood (ML) sequence detection using a Euclidean distance metric, a combination known as PRML. To simplify the implementation of the receiver, the target polynomial is chosen to be short in duration and constrained to have integer coefficients. At higher recording densities, the intersymbol interference (ISI) arising from a single pulse affects a larger number of adjacent symbol periods. Cont...
BLIND, ADAPTIVE EQUALIZATION FOR MULTICARRIER RECEIVERS
, 2004
"... Multicarrier modulation has been gaining in popularity in recent years. It has been implemented in systems such as Digital Subscriber Loops, broadcast High Definition Television in Europe, wireless local area network standards such as IEEE 802.11a, power line communications, and satellite radio. In ..."
Abstract

Cited by 2 (1 self)
 Add to MetaCart
(Show Context)
Multicarrier modulation has been gaining in popularity in recent years. It has been implemented in systems such as Digital Subscriber Loops, broadcast High Definition Television in Europe, wireless local area network standards such as IEEE 802.11a, power line communications, and satellite radio. In a multicarrier receiver, a timedomain equalizer (TEQ) is needed to mitigate the distortion due to the transmission channel. This typically takes the form of a filter that is designed such that the delay spread of the channelTEQ combination has a much shorter delay spread than that of the channel alone. This thesis has two thrusts: the primary goal is to propose, analyze, and simulate several blind, adaptive algorithms for designing the TEQ. The secondary goal is characterization and complexity reduction of both adaptive and nonadaptive TEQ designs. This will include examining symmetry of the impulse response and the locations of its zeros, as well as techniques to reuse calculations in laborious matrix computations.