OAM with acceleration
Multidimensional Waveforms | MATLAB
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ND-OTFS-OAM Under Acceleration & Imperfect CSI
ND-OTFS-OAM Under Acceleration & Imperfect CSI
Wireless communication in high-speed environments—such as autonomous cars, drones, and high-speed trains—faces major challenges due to rapid changes in the signal path. This research studies a new type of waveform called ND-OTFS-OAM, which combines three advanced technologies: OTFS (to handle fast-moving reflections), OAM (to pack more data into the same frequency), and N-D constellations (to reduce errors). The study focuses on two real-world problems: acceleration (changing speed) and imperfect channel information (when the receiver doesn’t know the channel perfectly). Using computer simulations, the authors show that acceleration and imperfect CSI both reduce signal strength and increase bit errors. However, the proposed system remains robust for voice and multimedia even under challenging conditions. The work helps guide the design of future 6G networks for high-mobility scenarios.
Key Contributions
Acceleration degrades performance – As acceleration increases from 1 to 10 m/s², bit errors rise significantly due to rapid changes in antenna alignment and Doppler shifts.
Imperfect CSI weakens the signal – Increasing CSI imperfection from 10% to 70% raises the bit error rate from ~0.00025 to ~0.01, directly reducing reliability.
Higher constellation dimensions improve robustness – Increasing the dimension of the N-D constellation boosts the minimum distance between symbols, reducing errors without needing more power.
OAM modes add capacity without extra errors – Adding more OAM modes increases data rate but does not significantly worsen bit error rate, making it an efficient multiplexing tool.
The system supports different applications – Voice can tolerate higher impairments, while data and telemetry require much lower error rates and better channel knowledge.
Methodology in brief
System setup – A transmitter and receiver each use a circular antenna array (UCA) to create OAM beams. OTFS modulation converts the signal to the delay-Doppler domain.
Channel modeling – A 3GPP mmWave channel (TDL-B) with multiple paths, Doppler shifts, and time-varying distances between antennas due to acceleration.
Imperfect CSI modeling – Added random perturbation to the channel matrix to simulate estimation errors and antenna misalignment.
Simulation parameters – 28 GHz carrier, 15 kHz subcarrier spacing, 120 km/h initial speed, acceleration from 1 to 10 m/s², QPSK/16QAM/64QAM, and BER as the main metric.
Results & Impact
The ND-OTFS-OAM system maintains reliable communication even with 50% CSI imperfection and 10 m/s² acceleration. For voice applications (target BER ~10⁻²), the system operates for ~5 minutes under 20% CSI error. Adding more OAM modes increases data rate without noticeably raising the bit error rate, confirming OAM as an efficient multiplexing method.
Outcomes:
Lavanya Mallampalli, Ch Santosh Reddy, and Debarati Sen. "Impact of Acceleration and Imperfect CSI on Multidimensional Waveforms in Doubly Dispersive Channel." IEEE Communications Letters, DOI: 10.1109/LCOMM.2026.3696283, (2026). [Paper]
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