Skew-Aware Joint Multi-Track Equalization for Array Reader-Based Interlaced Magnetic Recording

Abstract

Interlaced magnetic recording (IMR) enhanced with an array reader, named array reader-based IMR (ARIMR), has been introduced recently showing a tangible areal density capability gain over the conventional recording system. Joint read equalization is one of the key enablers to improve the bit-error-rate performance of the readback signals, which even shows potential for on-line processing of joint multi-track retrievals. However, the performance gain of ARIMR may not be guaranteed for the entire disk due to wide variations of the cross-track separation (CTS) between read sensors by the skew of the array and recording tracks. In order to mitigate the undesired skew effect in ARIMR, a novel joint multi-track equalization scheme is proposed in this paper with customized allocation of the array reader depending on the skew as well as the joint track center. Furthermore, individual readers in the array are not necessarily identical and their performance difference should be accounted for together with CTS for reader allocations. Therefore, the effective joint center of the target tracks is estimated in the proposed study to allocate the array reader for jointly accessing multiple tracks in ARIMR, even with undesired track mis-registration offsets. For performance evaluation, the proposed joint equalization with effective cross-track center allocation scheme is investigated by numerical ARIMR channel simulations with the micro-pixelated magnetic channel model. In the evaluation, varying CTS conditions are simulated to account for the skew impacts on ARIMR reading dual tracks and the corresponding effective cross-track center for placing the reader. Overall, off-track capability widths common for the two neighboring tracks can be evaluated for a broad range of array readers, which shows the feasibility of joint reading of dual tracks by ARIMR.