Low-Complexity Equalization for Orthogonal Time and Frequency Signaling (OTFS)

Abstract

Recently, a new precoding technique called orthogonal time-frequency signaling (OTFS) has been proposed for time- and frequency-selective communication channels. OTFS precodes a data frame with a complete set of spreading sequences and transmits the results via orthogonal frequency division multiplexing (OFDM). OTFS uses two dimensional (2D) linear spreading sequences in time and frequency which are the basis functions of a symplectic Fourier transform. OTFS allows the utilization of time- and frequency-diversity but requires maximum likelihood decoding to achieve full diversity. In this paper we show performance results of a low-complexity equalizer using soft-symbol feedback for interference cancellation after an initial minimum-mean square error equalization step. Performance results for an implementation in the delay-Doppler domain and in the time-frequency domain are compared. With our equalizer, OTFS achieves a gain of 5dB compared to OFDM for a bit error rate of $10^{-4}$ and a velocity of $200\text{km/h}$.

5 pages, 3 figures, submitted to IEEE 18th International Workshop on Signal Processing Advances in Wireless Communications (WCNC), Barcelona, Spain, April 2018

References in corpus (2)

• Delay and Doppler Spreads of Non-Stationary Vehicular Channels for Safety Relevant Scenarios
• OTFS - Orthogonal Time Frequency Space

Cited by in corpus (8)

• Orthogonal Delay-Doppler Division Multiplexing Modulation
• Orthogonal Time Sequency Multiplexing Modulation: Analysis and Low-Complexity Receiver Design
• OTFS Channel Estimation and Detection for Channels with Very Large Delay Spread
• Orthogonal Time Frequency Space Modulation
• Message Passing Based Structured Sparse Signal Recovery for Estimation of OTFS Channels with Fractional Doppler Shifts
• Embedded Pilot-Aided Channel Estimation for OTFS in Delay-Doppler Channels
• Low-complexity and Low-overhead Receiver for OTFS via Large-scale Antenna Array
• Iterative Detection for Orthogonal Time Frequency Space Modulation with Unitary Approximate Message Passing