Waveform Design for Joint Sensing and Communications in the Terahertz Band

The convergence of radar sensing and communication applications in the terahertz (THz) band has been envisioned as a promising technology, since it incorporates terabit-per-second (Tbps) data transmission and mm-level radar sensing in a spectrumand cost-efficient manner, by sharing both the frequency and hardware resources. However, the joint THz radar and communication (JRC) system faces considerable challenges, due to the peculiarities of the THz channel and front ends. To this end, the waveform design for THz-JRC systems with ultra-broad bandwidth is investigated in this paper. Firstly, by considering THz-JRC systems based on the co-existence concept, where both functions operate in a time-domain duplex (TDD) manner, a novel multi-subband quasi-perfect (MS-QP) sequence, composed of multiple Zadoff-Chu (ZC) perfect subsequences on different subbands, is proposed for target sensing, which achieves accurate target ranging and velocity estimation, whilst only requiring cost-efficient lowrate analog-to-digital converters (A/Ds) for sequence detection. Furthermore, the root index of each ZC subsequence of the MS-QP sequence is designed to eliminate the influence of doppler shift on the THz radar sensing. Finally, a data-embedded MS-QP (DE-MS-QP) waveform is constructed through timedomain extension of the MS-QP sequence, generating null frequency points on each subband for data This work was supported in part by the National Key R&D Program of China under Grant 2018YFB1801501, in part by Shenzhen Special Projects for the Development of Strategic Emerging Industries (201806081439290640), and in part by Shenzhen Wireless over VLC Technology Engineering Lab Promotion. (Corresponding author: Zhaocheng Wang.) T. Mao, J. Chen and Z. Wang are with Beijing National Research Center for Information Science and Technology, Department of Electronic Engineering, Tsinghua University, Beijing 100084, China, and Z. Wang is also with Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China. (e-mail: maotq18@mails.tsinghua.edu.cn, chenjx16@mails.tsinghua.edu.cn, zcwang@tsinghua.edu.cn). Q. Wang is with Huawei Device Co. Ltd., Shenzhen 518129, China (e-mail: steven wq@hotmail.com). Chong Han is with the UM-SJTU Joint Institute, Shanghai Jiao Tong University, Shanghai 200240, China (e-mail: chong.han@sjtu.edu.cn). G. K. Karagiannidis is with the Wireless Communications Systems Group (WCSG), Aristotle University of Thessaloniki, Thessaloniki 54 124, Greece (e-mail: geokarag@auth.gr).