Orthogonal time frequency space (OTFS) schemes have received significant attention recently, especially for high mobility scenarios. OTFS is a new 2-dimensional (2D) modulation and multiplexing technique proposed as an alternative to orthogonal frequency division multiplexing (OFDM) for next generation standard and beyond. In implementation, the Inverse Symplectic Fast Fourier Transform (ISFFT) performs as a pre-processing block while the Symplectic Fast Fourier Transform (SFFT) works as a post-processing block to OFDM systems. While OTFS is a robust orthogonal modulation scheme, the received delay-Doppler (DD) domain signal faces inter-carrier interference (ICI) and interference to other users as the exactness of decomposing the channel, though theoretically orthogonal, is still at best an approximation of reality in time varying environment. At high carrier frequencies as in the 6GHz band used for Wi-Fi 6E systems, the residual carrier frequency offset (CFO) of practical crystals induces a non-negligible ICI, leading to performance degradation. By integrating the ICI parallel cancellation (PC) scheme into the zero-padding (ZP) OTFS system, we present two novel two-path PC OTFS systems with two architectures to mitigate the CFO). Without estimating the residual CFO, both systems improve bit error rate (BER). Simulation shows several dB of BER improvement for two-path PC OTFS systems over the regular OTFS system when residual CFO exists.
Two-Path Parallel Cancellation ZP-OTFS Systems for Mitigating Residual Carrier Frequency Offset
2024-06-24
997367 byte
Conference paper
Electronic Resource
English
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