Chapter 10: Fractional Doppler and Off-Grid Effects

Learning Objectives

• Distinguish integer from fractional Doppler and quantify the associated leakage
• Derive the exact DD input-output relation under fractional Doppler, including the inter-Doppler interference kernel
• Apply the basis expansion model (BEM) to handle fractional offsets in channel estimation and detection
• Evaluate windowing and oversampled grid techniques for fractional-offset mitigation
• Quantify the practical BER and diversity impact of fractional Doppler on OTFS performance