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OFDM-Standard Compatible SC-NOFS Waveforms for Low-Latency and Jitter-Tolerance Industrial IoT Communications

Tongyang Xu, Shuangyang Li, Jinhong Yuan

TL;DR

This work tackles IIoT latency and jitter challenges by proposing an OFDM-compatible SC-NOFS waveform that uses irregular Sinc (irSinc) shaping to boost spectral efficiency. It employs a two-stage NOFS/INOFS framework with real-valued transforms and a neural-network-based training approach, maintaining compatibility with existing 5G PHY through an OFDM air interface and conventional channel estimation. Key contributions include the irSinc design, a dimension-reducing NOFS transform with spectral compression factor $\alpha=Q/M$, a two-stage SC-NOFS framework, and a neural-network training scheme that minimizes BER gaps while enabling pruning for lower complexity; hardware tests validate 18% timing-resource savings and up to 22% spectral efficiency gain. The results suggest SC-NOFS can deliver higher data density and lower latency in industrial IoT deployments without requiring major PHY upgrades, making it a practical pathway for 5G/6G-era IIoT communications.

Abstract

Traditional communications focus on regular and orthogonal signal waveforms for simplified signal processing and improved spectral efficiency. In contrast, the next-generation communications would aim for irregular and non-orthogonal signal waveforms to introduce new capabilities. This work proposes a spectrally efficient irregular Sinc (irSinc) shaping technique, revisiting the traditional Sinc back to 1924, with the aim of enhancing performance in industrial Internet of things (IIoT). In time-critical IIoT applications, low-latency and time-jitter tolerance are two critical factors that significantly impact the performance and reliability. Recognizing the inevitability of latency and jitter in practice, this work aims to propose a waveform technique to mitigate these effects via reducing latency and enhancing the system robustness under time jitter effects. The utilization of irSinc yields a signal with increased spectral efficiency without sacrificing error performance. Integrating the irSinc in a two-stage framework, a single-carrier non-orthogonal frequency shaping (SC-NOFS) waveform is developed, showcasing perfect compatibility with 5G standards, enabling the direct integration of irSinc in existing industrial IoT setups. Through 5G standard signal configuration, our signal achieves faster data transmission within the same spectral bandwidth. Hardware experiments validate an 18% saving in timing resources, leading to either reduced latency or enhanced jitter tolerance.

OFDM-Standard Compatible SC-NOFS Waveforms for Low-Latency and Jitter-Tolerance Industrial IoT Communications

TL;DR

This work tackles IIoT latency and jitter challenges by proposing an OFDM-compatible SC-NOFS waveform that uses irregular Sinc (irSinc) shaping to boost spectral efficiency. It employs a two-stage NOFS/INOFS framework with real-valued transforms and a neural-network-based training approach, maintaining compatibility with existing 5G PHY through an OFDM air interface and conventional channel estimation. Key contributions include the irSinc design, a dimension-reducing NOFS transform with spectral compression factor , a two-stage SC-NOFS framework, and a neural-network training scheme that minimizes BER gaps while enabling pruning for lower complexity; hardware tests validate 18% timing-resource savings and up to 22% spectral efficiency gain. The results suggest SC-NOFS can deliver higher data density and lower latency in industrial IoT deployments without requiring major PHY upgrades, making it a practical pathway for 5G/6G-era IIoT communications.

Abstract

Traditional communications focus on regular and orthogonal signal waveforms for simplified signal processing and improved spectral efficiency. In contrast, the next-generation communications would aim for irregular and non-orthogonal signal waveforms to introduce new capabilities. This work proposes a spectrally efficient irregular Sinc (irSinc) shaping technique, revisiting the traditional Sinc back to 1924, with the aim of enhancing performance in industrial Internet of things (IIoT). In time-critical IIoT applications, low-latency and time-jitter tolerance are two critical factors that significantly impact the performance and reliability. Recognizing the inevitability of latency and jitter in practice, this work aims to propose a waveform technique to mitigate these effects via reducing latency and enhancing the system robustness under time jitter effects. The utilization of irSinc yields a signal with increased spectral efficiency without sacrificing error performance. Integrating the irSinc in a two-stage framework, a single-carrier non-orthogonal frequency shaping (SC-NOFS) waveform is developed, showcasing perfect compatibility with 5G standards, enabling the direct integration of irSinc in existing industrial IoT setups. Through 5G standard signal configuration, our signal achieves faster data transmission within the same spectral bandwidth. Hardware experiments validate an 18% saving in timing resources, leading to either reduced latency or enhanced jitter tolerance.
Paper Structure (18 sections, 22 equations, 20 figures)

This paper contains 18 sections, 22 equations, 20 figures.

Table of Contents

  1. Introduction
  2. Irregular Sinc (irSinc)
  3. Multi-Carrier NOFS
  4. System Fundamentals
  5. Challenges
  6. Power Leakage
  7. Channel Estimation and Equalization
  8. Compatibility
  9. Single-Carrier NOFS
  10. Proposed SC-NOFS Signal Framework
  11. Neural Network Training Framework
  12. Performance Evaluation
  13. BER Performance
  14. PAPR Performance
  15. Frequency Selective Channel Performance
  16. ...and 3 more sections

Figures (20)

  • Figure 1: Time and frequency characteristics for Sinc, raised cosine (RC), and irSinc patterns.
  • Figure 2: irSinc pattern at each sub-carrier.
  • Figure 3: Block diagram of (a) multi-carrier OFDM communication link with complex-value signal processing, (b) multi-carrier NOFS communication link with real-value signal processing. C/R indicates complex to real conversion. R/C indicates real to complex conversion.
  • Figure 4: Sub-carrier shaping and packing schemes for Sinc shaped OFDM signal and irSinc shaped NOFS signal. Both signals have the same sub-carrier bandwidth while the NOFS signal has compressed sub-carrier spacing.
  • Figure 5: BER for multi-carrier NOFS signals. $\alpha$=0.7,0.5,0.4 indicate 43%,100%,150% spectral efficiency improvement, respectively.
  • ...and 15 more figures