Siming Peng

On Max-SIR Time–Frequency Packing for Multicarrier Faster-Than-Nyquist Signaling

In this letter, a novel maximizing signal-to-interference ratio (max-SIR) time–frequency packing scheme for multicarrier faster-than-Nyquist signaling is proposed. The proposed scheme is based on the low complexity symbol-by-symbol detector. Specifically, we optimize the time–frequency spacing under the given signaling efficiency to maximize the SIR, i.e., the ratio between the energy of useful signal and the intersymbol interference and intercarrier interference introduced by time–frequency packing. We show that the proposed max-SIR time–frequency packing outperforms other time–frequency packing schemes for both the symbol-by-symbol detection and coupled with successive interference cancellation.

Hexagonal Multicarrier Faster-Than-Nyquist Signaling

Multicarrier faster-than-Nyquist (MFTN) signaling is a spectral efficient modulation scheme for future communication systems. In MFTN signaling, the intersymbol interference (ISI) and intercarrier interference (ICI) are introduced intentionally by the time interval packing between adjacent symbols and frequency spacing packing between adjacent subcarriers. It is known that for multicarrier transmission over ISI and ICI channel, conventional rectangular lattice is not the optimal lattice structure. In this paper, the optimal hexagonal lattice-based MFTN signaling scheme is proposed. By appropriate staggering for conventional rectangular lattice, it is shown that the minimum Euclidean distance (or 2-DMazo limit) performance can be improved than conventional rectangular lattice-based MFTN signaling scheme. Moreover, a simple symbol-by-symbol receiver coupled with successive soft interference cancellation has been employed to recover the MFTN signals. Numerical results demonstrate that the hexagonal MFTN owns better bit error rate performance than conventional rectangular MFTN signaling scheme.

Symbol-by-symbol detection for faster-than-Nyquist signaling aided with frequency-domain precoding

Faster-than-Nyquist signaling is a promising waveform scheme in the fifth generation mobile communications for achieving higher spectrum efficiency. However, the FTN-caused intentional intersymbol interference will make the dectection process more complex. In this paper, a new precoding scheme is proposed for faster-than-Nyquist (FTN) signaling system aiming at reducing the burden of the receiver. Aided with the proposed frequency-domain precoding at the transmitter, the receiver can estimate the transmitted symbols by performing the symbol-by-symbol detection, which reduces the detection complexity dramatically. Moreover, the proposed precoding method can be applied into the high-order modulation directly, such as M-PSK or M-QAM. Further, the performance of proposed precoding scheme for FTN is verified and tested. Numerical results demonstrate that the proposed precoding scheme can not only realize symbol-by-symbol detection without bit-error-rate (BER) loss but also not broaden the spectrum of FTN signal at the transmitter.

A novel criterion for designing of nonlinear companding functions for peak-to-average power ratio reduction in multicarrier transmission systems

Nonlinear companding transform is a promising technique for the peak-to-average power ratio (PAPR) reduction in multicarrier transmission systems. However, conventional hard piecewise companding schemes often along with serious nonlinear distortion or complex companding parameters optimization embarrassment. In this paper, a novel designing criterion of nonlinear companding functions with more effective system performance is proposed. By transforming the Gaussian-distributed multicarrier signals into desirable statistics forms, we show that the smooth and differentiable concave probability distribution function of companded signals can obtain a better PAPR reduction and less out-of-band radiation as well as more simple companding parameters optimization than the traditional piecewise companding schemes. A detailed theoretical analysis and discussion is formulated, and then based on the analysis results, a novel trigonometric function companding scheme is presented and evaluated. Numerical results demonstrate that the companding schemes which consistent with the proposed criterion may significantly outperform conventional schemes by choosing the companding form and parameters appropriately.

Shaping pulse of faster-than-Nyquist signaling with truncated optimal detector

In this paper, we investigate the shaping pulse of faster-than-Nyquist (FTN) signaling by making use of the reduced complexity truncated optimal maximum-likelihood sequence detection. Specifically, the nonorthogonal Gaussian shaping pulse which owns the approximate optimal energy concentration in time-frequency domains is exploited. Moreover, for fair of comparisons, a general benchmark for different shaping pulses is adopted, and based on which, the Euclidean distance (or Mazo limit) and practical information rate performance of FTN signaling with Gaussian pulse and conventional T-orthogonal shaping pulses such as

Optimal multicarrier faster-than-Nyquist signaling under symbol-by-symbol detection

{\mathrm{sinc}}

PAPR Reduction of Multicarrier Faster-Than-Nyquist Signals With Partial Transmit Sequence

sinc pulse and root raised cosine pulse are evaluated. Theoretical analyses and numerical results demonstrate that when employed with truncated optimal detector and small channel memory at the receiver, the Gaussian pulse could achieve better BER and information rate performance than conventional T-orthogonal pulses.

Turbo equalization and detection for faster-than-nyqusit signaling: A comparative study

In this paper, two minimum mean-squared error (MMSE) turbo equalization and detection schemes for spectral efficient multicarrier faster-than-Nyquist (MFTN) signaling system are presented. First, the two-dimensional (2-D) soft input and soft output (SISO) MMSE equalization intended for magnetic recording channels, i.e., 2-D intersymbol interference (ISI), is extended to the detection of MFTN signals. Although the 2-D MMSE turbo equalization exhibits an attractive bit-error-rate (BER) performance under certain time-frequency spacing packing between adjacent symbols/subcarriers, the BER performance will be degraded when introducing serious intercarrier interference. Second, a 1-D SISO MMSE equalization combined with soft successive interference cancellation (SIC) is further proposed for the detection of MFTN signals, and it shows that the MMSE equalization combined with SIC could asymptotically approach the maximum a posterior equalization combined with SIC with negligible BER performance loss. Our computational complexity analysis and numerous simulation results demonstrate that the proposed MMSE turbo equalization schemes may be more preferred choice in the practical detection of MFTN signals.