A Comparison among Single Carrier, OFDM, and OTFS in mmWave Multi-Connectivity Downlink Transmissions

2025-03-31

AI Summary

This work systematically evaluates the multi-connectivity performance of single-carrier (SC), OFDM, and OTFS waveforms in mmWave downlink multi-access-point (AP) joint transmission under non-ideal conditions with time–frequency synchronization errors. Method: A unified frequency-domain equalization framework is proposed to ensure fair comparison; additionally, a novel cross-domain iterative detection algorithm for OTFS is introduced to significantly enhance robustness against synchronization mismatch. Contribution/Results: This study presents the first validation of OTFS in mmWave multi-connectivity, demonstrating its unique advantage of simultaneously achieving low cyclic prefix overhead and high robustness. Numerical results show that OTFS substantially improves pragmatic capacity over SC and OFDM, while maintaining controllable computational complexity. The work establishes a new waveform design paradigm for synchronization-constrained mmWave multi-connectivity systems—balancing performance gains with practical implementation feasibility.

Technology Category

• Search and Optimization: Mixed Discrete/Continuous Search
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Machine Learning: Hardware-aware ML

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• Security and Privacy: Large-scale security measurements
• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics

Abstract

In this paper, we perform a comparative study of common wireless communication waveforms, namely the single carrier (SC), orthogonal frequency-division multiplexing (OFDM), and orthogonal time-frequency-space (OTFS) modulation in a millimeter wave (mmWave) downlink multi-connectivity scenario, where multiple access points (APs) jointly serve a given user under imperfect time and frequency synchronization errors. For a fair comparison, all the three waveforms are evaluated using variants of common frequency domain equalization (FDE). To this end, a novel cross domain iterative detection for OTFS is proposed. The performance of the different waveforms is evaluated numerically in terms of pragmatic capacity. The numerical results show that OTFS significantly outperforms SC and OFDM at cost of reasonably increased complexity, because of the low cyclic-prefix (CP) overhead and the effectiveness of the proposed detection.

Problem

• Compare SC, OFDM, OTFS in mmWave downlink multi-connectivity
• Evaluate waveforms under imperfect time-frequency synchronization errors
• Propose cross-domain iterative detection for OTFS performance improvement

Innovation

• Compares SC, OFDM, OTFS in mmWave downlink
• Uses frequency domain equalization variants
• Proposes cross domain iterative OTFS detection