Abstract: High Mobility use case is an important deliverable of 5G NR technology. Wireless channels in such high mobility scenarios are highly dispersive and currently used waveforms like OFDM fail to perform well in these scenarios encountering high Doppler shifts. In this context, Orthogonal Time Frequency and Space (OTFS) is a recently introduced 2D modulation scheme that aims to achieve time and frequency diversity in time-dispersive channels. Literature suggests that Multi-Carrier Code Division Multiple Access (MC-CDMA) can also achieve high diversity gain due to spreading in frequency and time.

In this work, we compare two MC-CDMA schemes, one in which the symbols are spread only along frequency (MC-CDMA-FS) and one where the spread sequence is mapped over both time and frequency (MC-CDMA-TFS). Also, two different precoders based on Walsh-Hadamard (WH) and Zadoff-Chu (ZC) sequences are considered for both of these schemes. We present a comparative performance study of OTFS with MC-CDMA-FS and MC-CDMA-TFS using both the precoders for a single user case, in doubly dispersive channels. Our simulation results show that MC-CDMA-TFS and MC-CDMA-FS schemes with ZC precoding resembles OTFS and even performs better in channels with larger delay and Doppler spreads in the High Mobility scenario framework.

Event Details
Title: Comparing Precoded MC-CDMA with OTFS in High Mobility Environments.
Date: March 04, 2026 at 3:00 PM
Venue: Google Meet
Speaker: Mr. DIBYAJYOTI (EE18S014)
Guide: Dr. Giridhar K
Type: MS seminar

Updated: