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Shingled magnetic recording emerges as a promising near-term option to sustain the historical areal density growth of hard-disk drives while retaining conventional heads and media. Highly scaled shingled magnetic recording is subject to severe intertrack interference, which naturally demands 2-D read channel signal processing. By concurrently detecting multitrack read-back signals from a read head array, joint 2-D signal detection can fully exploit the 2-D interference to maximize the detection performance at the penalty of very high computational complexity. As modern read channel employs iterative signal detection and decoding and hard-disk drives are very cost sensitive, it is highly desirable to effectively reduce the 2-D signal detection computational complexity and hence silicon cost at minimal detection performance loss. This paper presents two low-complexity 2-D soft-output Viterbi algorithm (SOVA) detector design strategies for realizing multitrack joint 2-D detection, which represent different complexity versus performance tradeoffs. By carrying out simulations and application-specific integrated circuit design, this paper shows that, compared with the best symbol-based 2-D SOVA, it is feasible to achieve almost the same detection performance and meanwhile reduce the silicon area by more than 60% in three-track joint detection. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the secure relay beamforming problem for simultaneous wireless information and power transfer (SWIPT) in an amplify-and-forward (AF) two-way relay network. We consider scenarios that the eavesdropper's channel state information (CSI) is and is not available. When the eavesdropper's CSI is available, our objective is to maximize the achievable secrecy sum rate under transmit power constraint and energy harvesting constraint. Since the optimization problem is nonconvex, we derive its performance upper bound, which requires 2-D search, where a semidefinite programming is solved in each step. We also propose an upper bound-based rank-one solution by employing the Gaussian randomization method. To reduce computational complexity, we transform the optimization problem into a difference-of-convex programming and propose a sequential parametric convex approximation (SPCA)-based iterative algorithm to find a locally optimal solution. Furthermore, we also propose a zero-forcing (ZF)-based suboptimal solution. Simulation results demonstrate that the upper bound-based rank-one solution archives the performance almost the same as the upper bound that has high computational complexity. The low-complexity SPCA-based locally optimal solution performs close to the upper bound. The ZF-based suboptimal solution has the lowest computational complexity among the proposed solutions. When the eavesdropper's CSI is not available, we propose an artificial noise-aided secure relay beamforming scheme. [ABSTRACT FROM AUTHOR]

This paper considers the coherent integration problem for a maneuvering target with complex motions, where the velocity, acceleration, and jerk result in respectively the first-order range migration (FRM), second-order range migration (SRM), and third-order range migration (TRM) within the coherent pulse interval. A new coherent integration algorithm based on generalized keystone transform (KT) and second-order dechirp process is proposed, which employs the third-order KT, six-order KT, second-order KT, and fold factor searching to correct the TRM, SRM, and FRM, respectively. The range migration change during each step and computational complexity are also theoretically analyzed. Compared with the generalized Radon Fourier transform (GRFT) algorithm, the presented method can avoid the blind speed sidelobe (BSSL) and acquire close integration performance but with much lower computational cost. Simulations are provided to demonstrate the effectiveness. Finally, a generalized method, named generalized KT and generalized dechirp process (GKTGDP), is also introduced for the maneuvering target with arbitrary high-order range migration. [ABSTRACT FROM PUBLISHER]