In orthogonal time frequency space (OTFS) modulation, Zak transform approach is a natural approach for converting information symbols multiplexed in the DD domain directly to time domain for transmission, and vice versa at the receiver. Past research on OTFS has primarily considered a two-step approach where DD domain symbols are first converted to time-frequency domain which are then converted to time domain for transmission, and vice versa at the receiver. The Zak transform approach can offer performance and complexity benefits compared to the two-step approach. This paper presents an early investigation on the bit error performance of OTFS realized using discrete Zak transform (DZT). We develop a compact DD domain input-output relation for DZT-OTFS using matrix decomposition that is valid for both integer and fractional delay-Dopplers. We analyze the bit error performance of DZT-OTFS using pairwise error probability analysis and simulations. Simulation results show that 1) both DZT-OTFS and two-step OTFS perform better than OFDM, and 2) DZT-OTFS achieves better performance compared to two-step OTFS over a wide range of Doppler spreads.
翻译:在正交时频空间(OTFS)调制中,Zak变换方法是一种将DD域中多路复用的信息符号直接转换到时间域进行传输,接收端直接反过来,将接收的时间域信号转换为DD域信息符号的自然方法。过去有关OTFS的研究主要考虑了一种两步方法,即将DD域符号先转换为时间-频率域,然后将其转换为时间域进行传输,接收端将其反转。与这种两步方法相比,Zak变换方法可以提供性能和复杂度上的优势。本文对使用离散Zak变换(DZT)实现的OTFS的比特误差性能进行了早期研究。我们使用矩阵分解开发了DZT-OTFS的紧凑的DD域输入输出关系,该关系对整数和分数延迟-多普勒均有效。我们使用成对误差概率分析和仿真分析了DZT-OTFS的比特误差性能。仿真结果表明,1)DZT-OTFS和两步OTFS均优于OFDM;2)在广泛的多普勒展宽范围内,DZT-OTFS相对于两步OTFS实现了更好的性能。