Orthogonal Time Frequency Space (OTFS) Modulation Based Radar System

Abstract

Orthogonal time frequency space (OTFS) modulation was proposed to tackle the destructive Doppler effects in wireless communications, with potential applications to many other areas. In this paper, we investigate its application to radar systems, and propose a novel efficient OTFS-based matched filter algorithm for target range and velocity estimation. The proposed algorithm not only exhibits the inherent advantages due to multicarrier modulation of the existing orthogonal frequency division multiplexing (OFDM-) based radar algorithms but also provides additional benefits to improve radar capability. Similar to OFDM, OTFS spreads the transmitted signal in the entire time-frequency resources to exploit the full diversity gains for radar processing. However, OTFS requires less cyclic prefix, and hence, shorter transmission duration than OFDM, allowing longer range radar and/or faster target tracking rate. Additionally, unlike OFDM, OTFS is inter-carrier interference-free, enabling larger Doppler frequency estimation. We demonstrate the performance of the proposed algorithm using numerical results under different system settings.

Performance Analysis of Joint Radar and Communication using OFDM and OTFS

“…In contrast, the current work considers ML estimator without neglecting the fractional part of Doppler and delay shifts, while restricting to Doppler shifts of practical relevance for automotive applications, such that the inter-carrier interference (ICI) incurred by OFDM is definitely negligible. Under these conditions, we obtain different conclusions as [8].…”

“…where the approximation follows by letting ν max ∆f 1 . Under the approximated channel input-output relation (8), it readily follows that the Doppler shift and the delay are decoupled, which makes joint range and velocity estimation simple (see e.g. [1], [7]).…”

“…However, none of these works has addressed explicitly the joint performance in terms of MSE and achievable communication rate. A comparison of radar estimation between OTFS and OFDM has been independently developed in a very recent work [8]. By neglecting part of the fractional Doppler and delay shifts and further focusing on a low-complexity matched filter approach for OTFS, this work concluded that OTFS has some advantages over OFDM since it can handle larger Doppler shifts and longer range.…”

Tecnología de Modulación en el Espacio de Tiempo-Frecuencia Ortogonal

“…Considerando las numerosas investigaciones en curso sobre el escenario 5G y las comunicaciones móviles de esta tecnología, podemos destacar las referentes a la modulación en el Espacio de Tiempo-Frecuencia Ortogonal (OTFS, por sus siglas en inglés) [1][2][3][4][5][6][7][8][9][10]. La modulación OTFS puede compensar el retraso y el efecto de propagación Doppler de alta velocidad mediante el uso de las Transformadas Inversa-Discreta / Discreta de Fourier (IDFT / DFT, por sus siglas en inglés, respectivamente) en dos dimensiones (2D), que convierten la señal del dominio del tiempo al dominio de la frecuencia.…”

“…La figura 1 muestra el diagrama de bloques del sistema de comunicación con modulaciones OFDM y OTFS de un solo portador, en donde se pueden observar todos los procesos antes descritos. Por todo lo mencionado anteriormente, este trabajo se centra en los conceptos básicos de la tecnología de modulación OTFS, que según las investigaciones recientes [1][2][3][4][5][6][7][8][9][10], es la que mejor responde a las nuevas necesidades de aumento en la velocidad y la capacidad de los canales de transmisión; además de que compensa de forma simple los retrasos Doppler en entornos de alta movilidad [1].…”