Decision Feedback Equalization (original) (raw)
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Equalization Concepts by TI (tutorial, 1994)
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Decision device optimization for soft decision feedback equalization
Proc. of CISS 2000, 2000
Abstract—This paper considers the use of soft decisions to mitigate error propagation in a decision feedback equalizer (DFE). The decision device for the soft decision feedback equalizer is optimized by minimizing the meansquared error (MSE) cost function defined ...
Hardware emulation of multi-level decision feedback equalization
IEEE Transactions on Magnetics, 1996
The bit error rate (BER) performance of a Multi-level decision feedback equalizer (MDFE) for a magnetic recording channel is evaluated. The unique equalization scheme designed for 2/3(1,7) RLL codes was emulated on the RAM-DFE IC. Measurements with a synchronous clock at 54Msps demonstrated that raising the inner target levels improves the performance considerably. It was found that MDFE outperforms conventional DFE at the same symbol density of PW50=2.5T and yields similar performance at the same user density of 1.78.
Decision feedback equalizers for high speed data communications
2003
This work shows the performance of different decision feedback equalizers (DFEs) for high-speed data transmission over a telephone line. The analyzed structures are: the interference intersymbol-predictive decision feedback equalizer (ISI-DFE), the decision feedback equalizer with noise predictor (NP-DFE) and the hybrid-type DFE (H-DFE).
Mitigating error propagation effects in a decision feedback equalizer
IEEE Transactions on Communications, 2001
We present an approximate analysis approach to the computation of probability of error and mean burst error length for a decision feedback equalizer (DFE) that takes into account feedback of decision errors. The method uses a reduced-state Markov model of the feedback process and is applicable to linear modulation formats. We use this technique to analyze a DFE design that mitigates the effects of feedback error by incorporating a soft decision device into the feedback path and a norm constraint on the feedback filter weights. We apply the DFE design and analysis approach to a dispersive multipath propagation environment.
Performance evaluation of decision feedback equalizer under mismatch
1983
Dispersive communication channels suffer from intersymbol interference (ISI) due to bandwidth limitations and the requirements of using high data rate. The decision feedback equalizer (DFE) was introduced as a suboptimum nonlinear processor to combat ISI for known channel characteristics. In this paper, the performance of the DFE is investigated for a mismatched channel. The channel characteristic, under mismatch, is allowed to vary with respect to a specified design channel characteristic, for which the DFE is designed. This investigation allows an examination of the limits of mismatch of the channel characteristic for which the performance of the DFE is adequate. In this way, the robustness of the DFE for a given class of communication channels characterized by all the possible variations of the channel characteristic can be examined.
A Soft Decision Feedback Equalizer
1999
In this paper, a method to reduce the error propagation in Decision Feedback Equalizers (DFEs) is addressed. An M -level staircase nonlinearity is proposed for the feedback chain of the DFE. Analytical results are presented to show advantages obtained with increasing M . Finally, the saturation nonlinearity (the limiting case as M tends to in nity) is suggested for the DFE. Simulations are provided to support the proposed DFE. Its performance is found to be better than that of the recently proposed Erasure DFE.
Multi-level decision feedback equalization for saturation recording
IEEE Transactions on Magnetics, 1993
Fixed-delay tree search with decision feedback (FDTSIDF) has been proposed for retrieving data from hard disk drives. One problem with the algorithm as originally posed is that 4 additions and 1 multiplication sets the critical path delay through the detector. This paper explores the decision space in FDTSIDF using linear discriminants. On recording channels using 2/3(1, 7) run-length limited coding, a detector achieving the performance of FDTSIDG can be implemented with a 2-tap transversal filter. The feedback loop can be rearranged so that this transversal filter no longer resides in the forward path of the feedback loop. Instead its transfer function is incorporated into the specification of the forward and backward equalizers. This modification leads to the simpler architecture of decision feedback equalizer (DFE), where the slicer performs binary decisions on a multi-level signal. Implementation issues pertaining to phase detection, gain detection, dc detection and adaptive equalization using a least-means squared technique will also be addressed. Simulation results demonstrate adaptive equalization, where the desired model is generated by a 3-tap transversal filter consisting of only adders, delays, multiplexers and 1 programmable coefficient.
1997
The unshielded twisted pair can be used as a transmission media for local distribution networks. To maintain a high transmission throughput, an analog or a digital adaptive channel equalizer is usually required in the receiver to minimize the effect of inter-symbol interference. Under the observation that the high sampling rate high precision A D and subsequent digital adaptive signal processing is an expensive approach, a direct equalization method, where the equalizer is implemented in the transmitter, is proposed for symmetrical twisted pair transmission channels. This direct equalization method can also be applied to the analog equalization approach for reduced system complexity.