Vichienchom, Kasin
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Item type:Publication, Improved 2-D graph-based detectors for 2-D interference channels(2014-11-01); The 2-D interference channels, which consist of intersymbol interference as well as intertrack interference (ITI), appear in highdensity recording channels. A graph-based detector has received much attention since it is a real 2-D detector, which can recover data from multiple tracks or each 2-D page simultaneously. In this paper, we propose two approaches to improve the performances of graph-based detectors. For the first method (M1), which processes data on a 2-D page, the system equalizes 2-D interference channel into two 1-D targets, horizontal and vertical directions followed by two corresponding graph detectors. The second method (M2) is similar to the first one, but the 2-D channel is equalized into two 2-D targets with and without cornered ITIs, respectively, in order to better handle the effects of cornered ITIs. Compared with the full-graph detector, the method M1 offers reduced-complexity due the fewer number of edges from the factor nodes. The simulation results on the 3 × 3 channel matrix with 2% cornered ITI show that the proposed methods achieve the gains of about 1.0 and 1.7 dB, respectively, at the BER of 10<sup>-5</sup> over the full graph detector. As the cornered ITI levels increase, the method M2 gives the larger gains over the others. When the media noise is accounted for, the method M2 still gives the best performances. Finally, the mutual information of the three graph detectors for the 2-D channels is computed and compared. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Modified graph-based detection methods for two-dimensional interference channels(2012-10-29); ; Two-dimensional (2-D) interference channels with inter-symbol interference (ISI) and inter-track interference (ITI) exist in the magnetic recording systems at high areal density. A number of 2-D detection methods have recently been proposed for the multi-track processing of the 2-D channels. Graph-based detector with the belief propagation algorithm appears as an alternative method, but at a degraded performance and high complexity level. In this work, we propose two methods to modify the graph-based (GB) detector. One applies a serial scheduling to the GB detector, while the other modifies the GB detection by ignoring some connections during one direction of the reliability updates in the factor graph leading to the reduction of short cycles. The simulation results show that the proposed GB detectors give better bit error rate performances than the other GB detectors. © 2012 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Performance of Log-MAP algorithm for graph-based detections on the 2-D interference channel(2014-01-01); The read channel of magnetic recording system is affected by two-dimensional interference channel that is a combination of inter-symbol interference and inter-track interference. Inter-track interference is one of the biggest challenges in the high density magnetic recording systems and it can degrade the performance of the channels. In this work, we compare three variations of log-MAP algorithms for graph-based detectors in two-dimensional interference channels. The simulation results show the performance of the graph-based detector with the full log-MAP and extended log-MAP algorithms achieve the gains of about 0.1 and 0.05 dB at BER = 10<sup>-5</sup>, over the max approximation on bit patterned media recording system with the areal density 2.5 Tbits/in<sup>2</sup>. © 2014 IEEE.1