Orthogonal Time Sequency Multiplexing Modulation

High Performance ◽

High Mobility ◽

Low Complexity ◽

Modulation Scheme ◽

Frequency Space ◽

Time Frequency ◽

Single Carrier ◽

The Time Domain

This paper proposes <i>orthogonal time sequency multiplexing</i> (OTSM), a novel single carrier modulation scheme based on the well known Walsh-Hadamard transform (WHT) combined with row-column interleaving, and zero padding (ZP) between blocks in the time-domain. The information symbols in OTSM are multiplexed in the delay and sequency domain using a cascade of time-division and Walsh-Hadamard (sequency) multiplexing. By using the WHT for transmission and reception, the modulation and demodulation steps do not require any complex multiplications. We then propose two low-complexity detectors: (i) a simpler non-iterative detector based on a single tap minimum mean square time-frequency domain equalizer and (ii) an iterative time-domain detector. We demonstrate, via numerical simulations, that the proposed modulation scheme offers high performance gains over orthogonal frequency division multiplexing (OFDM) and exhibits the same performance of orthogonal time frequency space (OTFS) modulation, but with lower complexity. In proposing OTSM, along with simple detection schemes, we offer the lowest complexity solution to achieving reliable communication in high mobility wireless channels, as compared to the available schemes published so far in the literature.

Orthogonal Time Sequency Multiplexing Modulation

10.36227/techrxiv.13580201 ◽

2021 ◽

Author(s):

Tharaj Thaj ◽

Emanuele Viterbo

Keyword(s):

Time Domain ◽

High Performance ◽

High Mobility ◽

Low Complexity ◽

Modulation Scheme ◽

Frequency Space ◽

Time Frequency ◽

Single Carrier ◽

The Time Domain

This paper proposes <i>orthogonal time sequency multiplexing</i> (OTSM), a novel single carrier modulation scheme based on the well known Walsh-Hadamard transform (WHT) combined with row-column interleaving, and zero padding (ZP) between blocks in the time-domain. The information symbols in OTSM are multiplexed in the delay and sequency domain using a cascade of time-division and Walsh-Hadamard (sequency) multiplexing. By using the WHT for transmission and reception, the modulation and demodulation steps do not require any complex multiplications. We then propose two low-complexity detectors: (i) a simpler non-iterative detector based on a single tap minimum mean square time-frequency domain equalizer and (ii) an iterative time-domain detector. We demonstrate, via numerical simulations, that the proposed modulation scheme offers high performance gains over orthogonal frequency division multiplexing (OFDM) and exhibits the same performance of orthogonal time frequency space (OTFS) modulation, but with lower complexity. In proposing OTSM, along with simple detection schemes, we offer the lowest complexity solution to achieving reliable communication in high mobility wireless channels, as compared to the available schemes published so far in the literature.

Orthogonal Time Sequency Multiplexing Modulation: Analysis and Low-Complexity Receiver Design

10.36227/techrxiv.14404460 ◽

2021 ◽

Author(s):

Tharaj Thaj ◽

Emanuele Viterbo ◽

Yi Hong

Keyword(s):

High Performance ◽

Error Control ◽

Estimation Method ◽

Low Complexity ◽

Modulation Scheme ◽

Receiver Design ◽

Error Performance ◽

Frequency Space ◽

This paper proposes orthogonal time sequency multiplexing (OTSM), a novel single carrier modulation scheme that places information symbols in the delay-sequency domain followed by a cascade of time-division multiplexing (TDM) and Walsh-Hadamard sequence multiplexing. Thanks to the Walsh Hadamard transform (WHT), the modulation and demodulation do not require complex domain multiplications. For the proposed OTSM, we first derive the input-output relation in the delay-sequency domain and present a low complexity detection method taking advantage of zero-padding. We demonstrate via simulations that OTSM offers high performance gains over orthogonal frequency division multiplexing (OFDM) and similar performance to orthogonal time frequency space (OTFS), but at lower complexity owing to WHT. Then we propose a low complexity time-domain channel estimation method. Finally, we show how to include an outer error control code and a turbo decoder to improve error performance of the coded system.

Orthogonal Time Sequency Multiplexing Modulation: Analysis and Low-Complexity Receiver Design

10.36227/techrxiv.14404460.v2 ◽

2021 ◽

Author(s):

Tharaj Thaj ◽

Emanuele Viterbo ◽

Yi Hong

Keyword(s):

High Performance ◽

Error Control ◽

Estimation Method ◽

Low Complexity ◽

Modulation Scheme ◽

Receiver Design ◽

Error Performance ◽

Frequency Space ◽

This paper proposes orthogonal time sequency multiplexing (OTSM), a novel single carrier modulation scheme that places information symbols in the delay-sequency domain followed by a cascade of time-division multiplexing (TDM) and Walsh-Hadamard sequence multiplexing. Thanks to the Walsh Hadamard transform (WHT), the modulation and demodulation do not require complex domain multiplications. For the proposed OTSM, we first derive the input-output relation in the delay-sequency domain and present a low complexity detection method taking advantage of zero-padding. We demonstrate via simulations that OTSM offers high performance gains over orthogonal frequency division multiplexing (OFDM) and similar performance to orthogonal time frequency space (OTFS), but at lower complexity owing to WHT. Then we propose a low complexity time-domain channel estimation method. Finally, we show how to include an outer error control code and a turbo decoder to improve error performance of the coded system.

Orthogonal Time Sequency Multiplexing Modulation: Analysis and Low-Complexity Receiver Design

10.36227/techrxiv.14404460.v1 ◽

2021 ◽

Author(s):

Tharaj Thaj ◽

Emanuele Viterbo ◽

Yi Hong

Keyword(s):

High Performance ◽

Error Control ◽

Estimation Method ◽

Low Complexity ◽

Modulation Scheme ◽

Receiver Design ◽

Error Performance ◽

Frequency Space ◽

This paper proposes orthogonal time sequency multiplexing (OTSM), a novel single carrier modulation scheme that places information symbols in the delay-sequency domain followed by a cascade of time-division multiplexing (TDM) and Walsh-Hadamard sequence multiplexing. Thanks to the Walsh Hadamard transform (WHT), the modulation and demodulation do not require complex domain multiplications. For the proposed OTSM, we first derive the input-output relation in the delay-sequency domain and present a low complexity detection method taking advantage of zero-padding. We demonstrate via simulations that OTSM offers high performance gains over orthogonal frequency division multiplexing (OFDM) and similar performance to orthogonal time frequency space (OTFS), but at lower complexity owing to WHT. Then we propose a low complexity time-domain channel estimation method. Finally, we show how to include an outer error control code and a turbo decoder to improve error performance of the coded system.

Low-Complexity Blind Selected Mapping Scheme for Peak-to-Average Power Ratio Reduction in Orthogonal Frequency-Division Multiplexing Systems

Information ◽

10.3390/info9090220 ◽

2018 ◽

Vol 9 (9) ◽

pp. 220 ◽

Cited By ~ 3

Author(s):

Yujie Xia ◽

Jinwei Ji

Keyword(s):

Time Domain ◽

Average Power ◽

Low Complexity ◽

Power Ratio ◽

Frequency Division ◽

Phase Rotation ◽

Rotation Vectors ◽

The Time Domain ◽

Ofdm Signals

Orthogonal frequency-division multiplexing (OFDM) is an attractive multicarrier technique for the simplicity of equalization and high data throughput. However, the transmitted OFDM signal has a very high peak-to-average power ratio (PAPR), which severely degrades the performance of practical OFDM systems and reduces the efficiency of high-power amplifiers (HPA). The selected mapping (SLM) scheme is an effective PAPR reduction method of OFDM signals. However, this approach usually requires side information (SI) transmission, which increases the difficulty of the hardware implementation with high complexity and reduces the data transmission rate. In this paper, based on designing phase rotation vectors in the time domain, a novel blind SLM method with low complexity is proposed to reduce the PAPR of OFDM signals. At the transmitter, the proposed method properly designs the phase rotation vectors in the time domain, which can be considered as an equivalent wireless channel without SI transmission. At the receiver, the effect of phase rotation vectors can be removed by the conventional channel estimation method, and the data demodulation processing can be easily performed by the frequency domain equalization. Simulation results show that the proposed scheme can achieve low complexity in PAPR reduction and has great robustness in bit error rate (BER) performance compared to the other low-complexity SLM PAPR schemes.

Low Complexity Iterative Rake Decision Feedback Equalizer for Zero-Padded OTFS systems

10.36227/techrxiv.13246931.v1 ◽

2020 ◽

Author(s):

Tharaj Thaj ◽

Emanuele Viterbo

Keyword(s):

Minimum Mean Square Error ◽

Low Complexity ◽

Error Correcting Codes ◽

Decision Feedback ◽

Maximal Ratio Combining ◽

Modulation Scheme ◽

Decision Feedback Equalizer ◽

Input Output ◽

<div>This paper presents a linear complexity iterative rake detector for the recently proposed orthogonal time frequency space (OTFS) modulation scheme. The basic idea is to extract and coherently combine the received multipath components of the transmitted symbols in the delay-Doppler grid using maximal ratio combining (MRC) to improve the SNR of the combined signal. We reformulate the OTFS input-output relation in simple vector form by placing guard null symbols or zero padding (ZP) in the delay-Doppler grid and exploiting the resulting circulant property of the blocks of the channel matrix. Using this vector input-output relation we propose a low complexity iterative decision feedback equalizer (DFE) based on MRC. The performance and complexity of the proposed detector favorably compares with the state of the art message passing detector. An alternative time domain MRC based detector is also proposed for even faster detection. We further propose a Gauss-Seidel based over-relaxation parameter in the rake detector to improve the performance and the convergence speed of the iterative detection. We also show how the MRC detector can be combined with outer error-correcting codes to operate as a turbo DFE scheme to further improve the error performance. </div><div>All results are compared with a baseline orthogonal frequency division multiplexing (OFDM) scheme employing a single tap minimum mean square error (MMSE) equalizer.</div>

Low Complexity Iterative Rake Decision Feedback Equalizer for Zero-Padded OTFS systems

10.36227/techrxiv.13246931.v2 ◽

2021 ◽

Author(s):

Tharaj Thaj ◽

Emanuele Viterbo

Keyword(s):

Minimum Mean Square Error ◽

Low Complexity ◽

Error Correcting Codes ◽

Decision Feedback ◽

Maximal Ratio Combining ◽

Modulation Scheme ◽

Decision Feedback Equalizer ◽

Input Output ◽

<div>This paper presents a linear complexity iterative rake detector for the recently proposed orthogonal time frequency space (OTFS) modulation scheme. The basic idea is to extract and coherently combine the received multipath components of the transmitted symbols in the delay-Doppler grid using maximal ratio combining (MRC) to improve the SNR of the combined signal. We reformulate the OTFS input-output relation in simple vector form by placing guard null symbols or zero padding (ZP) in the delay-Doppler grid and exploiting the resulting circulant property of the blocks of the channel matrix. Using this vector input-output relation we propose a low complexity iterative decision feedback equalizer (DFE) based on MRC. The performance and complexity of the proposed detector favorably compares with the state of the art message passing detector. An alternative time domain MRC based detector is also proposed for even faster detection. We further propose a Gauss-Seidel based over-relaxation parameter in the rake detector to improve the performance and the convergence speed of the iterative detection. We also show how the MRC detector can be combined with outer error-correcting codes to operate as a turbo DFE scheme to further improve the error performance. </div><div>All results are compared with a baseline orthogonal frequency division multiplexing (OFDM) scheme employing a single tap minimum mean square error (MMSE) equalizer.</div>

Low Complexity Iterative Rake Decision Feedback Equalizer for Zero-Padded OTFS systems

10.36227/techrxiv.13246931 ◽

2020 ◽

Author(s):

Tharaj Thaj ◽

Emanuele Viterbo

Keyword(s):

Minimum Mean Square Error ◽

Low Complexity ◽

Error Correcting Codes ◽

Decision Feedback ◽

Maximal Ratio Combining ◽

Modulation Scheme ◽

Decision Feedback Equalizer ◽

Input Output ◽

<div>This paper presents a linear complexity iterative rake detector for the recently proposed orthogonal time frequency space (OTFS) modulation scheme. The basic idea is to extract and coherently combine the received multipath components of the transmitted symbols in the delay-Doppler grid using maximal ratio combining (MRC) to improve the SNR of the combined signal. We reformulate the OTFS input-output relation in simple vector form by placing guard null symbols or zero padding (ZP) in the delay-Doppler grid and exploiting the resulting circulant property of the blocks of the channel matrix. Using this vector input-output relation we propose a low complexity iterative decision feedback equalizer (DFE) based on MRC. The performance and complexity of the proposed detector favorably compares with the state of the art message passing detector. An alternative time domain MRC based detector is also proposed for even faster detection. We further propose a Gauss-Seidel based over-relaxation parameter in the rake detector to improve the performance and the convergence speed of the iterative detection. We also show how the MRC detector can be combined with outer error-correcting codes to operate as a turbo DFE scheme to further improve the error performance. </div><div>All results are compared with a baseline orthogonal frequency division multiplexing (OFDM) scheme employing a single tap minimum mean square error (MMSE) equalizer.</div>

Separating Multiple Moving Sources by Microphone Array Signals for Wayside Acoustic Fault Diagnosis

Journal of Vibration and Acoustics ◽

10.1115/1.4043508 ◽

2019 ◽

Vol 141 (5) ◽

Author(s):

Wei Xiong ◽

Qingbo He ◽

Zhike Peng

Keyword(s):

Fault Diagnosis ◽

Time Domain ◽

Feature Matching ◽

Matching Pursuit ◽

Microphone Array ◽

Time Frequency ◽

Moving Sources ◽

The Time Domain ◽

Envelope Spectrum ◽

Threshold Setting

Wayside acoustic defective bearing detector (ADBD) system is a potential technique in ensuring the safety of traveling vehicles. However, Doppler distortion and multiple moving sources aliasing in the acquired acoustic signals decrease the accuracy of defective bearing fault diagnosis. Currently, the method of constructing time-frequency (TF) masks for source separation was limited by an empirical threshold setting. To overcome this limitation, this study proposed a dynamic Doppler multisource separation model and constructed a time domain-separating matrix (TDSM) to realize multiple moving sources separation in the time domain. The TDSM was designed with two steps of (1) constructing separating curves and time domain remapping matrix (TDRM) and (2) remapping each element of separating curves to its corresponding time according to the TDRM. Both TDSM and TDRM were driven by geometrical and motion parameters, which would be estimated by Doppler feature matching pursuit (DFMP) algorithm. After gaining the source components from the observed signals, correlation operation was carried out to estimate source signals. Moreover, fault diagnosis could be carried out by envelope spectrum analysis. Compared with the method of constructing TF masks, the proposed strategy could avoid setting thresholds empirically. Finally, the effectiveness of the proposed technique was validated by simulation and experimental cases. Results indicated the potential of this method for improving the performance of the ADBD system.