Iterative Parallel–Serial Detection Structure Using MAP Algorithm for Bit-Patterned Media Recording Systems

Abstract

In bit-patterned media recording (BPMR), data are modulated into the magnetic poles and stored in the magnetic islands. Thus, to increase the areal density (AD) of the storage device, we should reduce the distance between the magnetic islands. This leads to a two-dimensional (2-D) interference, wherein each island is affected by the neighboring islands. Therefore, to handle the 2-D interference, we proposed a parallel–serial structure of the detection based on the maximum <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$a$ </tex-math></inline-formula> posteriori (MAP) algorithm. The equalized received signal was fed to two branches in parallel. One branch was in the order of horizontal and then vertical detections, and the other was in the reverse order of vertical and horizontal detections. With the MAP algorithm, the serial structure of two branches can improve the bit error rate (BER) performance of the detection. Moreover, we can extract the extrinsic information from the output of the MAP algorithm of two branches and create the iteration of the parallel structure. The original signal was restored with higher accuracy after each iteration. The simulation results showed that the iterative parallel–serial detection structure using MAP improved the BER performance compared to those in previous studies with only parallel or serial structures.