@article{liu_otfs-based_2025,

title = {OTFS-Based CV-QKD Systems for Doubly Selective THz Channels},

author = {Xin Liu and Chao Xu and Soon Xin Ng and Lajos Hanzo},

url = {https://ieeexplore.ieee.org/document/10857395},

doi = {10.1109/TCOMM.2025.3535889},

issn = {1558-0857},

year  = {2025},

date = {2025-08-01},

urldate = {2025-10-08},

journal = {IEEE Transactions on Communications},

volume = {73},

number = {8},

pages = {6274–6289},

abstract = {The feasibility of continuous variable quantum key distribution (CV-QKD) is considered in the Terahertz (THz) band, experiencing time-varying and frequency-selective fading. Advanced multi-carrier modulation is required for improving the secret key rate (SKR). However, the hostile quantum channel requires powerful classical channel coding schemes for maintaining an adequate reconciliation performance. Against this background, for the first time in the open literature, we propose a multi-carrier quantum transmission regime that incorporates both orthogonal frequency division multiplexing (OFDM) and orthogonal time frequency space (OTFS) transmission over doubly selective fading THz channels. Furthermore, we propose a modified multi-dimensional reconciliation algorithm for CV-QKD, facilitating the integration of OFDM/OTFS quantum transmission with low-density parity check (LDPC) coded key reconciliation. Moreover, we harness multiple-input multiple-output (MIMO) beamforming for mitigating the severe THz path loss. Our SKR analysis results demonstrate that the proposed OTFS-based and LDPC-assisted CV-QKD system is capable of outperforming its OFDM counterpart in mobile wireless scenarios. Moreover, we also demonstrate that increasing the MIMO dimension reduces the transmission power required for achieving the secure transmission distance target.},

keywords = {Array signal processing, continuous variable quantum key distribution (CV-QKD), Faces, Fading channels, low-density parity check (LDPC), multiple-input multiple-out (MIMO), OFDM, Orthogonal frequency division multiplexing (OFDM), orthogonal time frequency space (OTFS), Parity check codes, Random variables, secret key rate (SKR), Symbols, Terahertz (THz), Terahertz communications, Time-frequency analysis, Vectors},

pubstate = {published},

tppubtype = {article}

}

@article{du_flexible_2025,

title = {Flexible Waveform Design for RO-ISAC Based on OFDM-Embedded Maximum Length Sequence},

author = {Jia Du and Chen Chen and Zhihong Zeng and Dengke Wang and Jia Ye and Jian Song and Harald Haas},

url = {https://ieeexplore.ieee.org/document/11098738/},

doi = {10.1109/LWC.2025.3593253},

issn = {2162-2337, 2162-2345},

year  = {2025},

date = {2025-01-01},

urldate = {2025-08-27},

journal = {IEEE Wireless Communications Letters},

pages = {1–1},

keywords = {LRDC, Optical integrated sensing and communication (O-ISAC), Orthogonal frequency division multiplexing (OFDM)},

pubstate = {published},

tppubtype = {article}

}

@article{liu_hybrid_2025,

title = {Hybrid Beamforming Assisted OTFS-Based CV-QKD Systems for Doubly Selective THz Channels},

author = {Xin Liu and Chao Xu and Stephen Wang and Soon Xin Ng and Lajos Hanzo},

url = {https://ieeexplore.ieee.org/document/11069272},

doi = {10.1109/TCOMM.2025.3585501},

issn = {1558-0857},

year  = {2025},

date = {2025-01-01},

urldate = {2025-10-08},

journal = {IEEE Transactions on Communications},

pages = {1–1},

abstract = {Continuous-variable quantum key distribution (CV-QKD) maps information onto the quadrature components of electromagnetic waves, so that off-the-shelf wireless transceivers can be utilized. This motivates the move from optical to Terahertz (THz) bands. However, wireless THz channels suffer from severe path loss, while the mobility of wireless users imposes doubly selective fading. Against this background, we propose a new CV-QKD regime that relies on hybrid beamforming (HBF) assisted multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) and orthogonal time frequency space (OTFS) system, where the channel’s transmissivity and robustness against double selectivity are overcome by HBF and OTFS, respectively. Secondly, in order to provide channel state information (CSI) for both the transmitter (CSI-T) and receiver (CSI-R), practical channel estimation methods are conceived. They operate in the time-frequency domain for OFDM and in the delay-Doppler domain for OTFS. Thirdly, soft-decision detection is devised for our MIMO OFDM/OTFS aided multi-dimensional reconciliation (MDR) scheme. Low-density parity-check (LDPC) coding is invoked for further improving secure CV-QKD transmission distance in the THz band. Our simulation results demonstrate that the proposed HBF MIMO OTFS-based CV-QKD system relying on realistic estimated CSI is capable of achieving an adequate secret key rate (SKR) and secure transmission distance in hostile doubly selective THz channels.},

keywords = {Array signal processing, Channel estimation, continuous variable quantum key distribution (CV-QKD), Decoding, Fading channels, hybrid beamforming (HBF), low-density parity check (LDPC), multiple-input multiple-out (MIMO), OFDM, Orthogonal frequency division multiplexing (OFDM), orthogonal time frequency space (OTFS), Parity check codes, secret key rate (SKR), Terahertz (THz), Terahertz communications, Time-frequency analysis, Vectors, Wireless communication},

pubstate = {published},

tppubtype = {article}

}

@article{cui_retroreflective_2024,

title = {Retroreflective optical ISAC using OFDM: channel modeling and performance analysis},

author = {Yuanxin Cui and Chen Chen and Yueping Cai and Zhihong Zeng and Min Liu and Jia Ye and Sihua Shao and Harald Haas},

url = {https://opg.optica.org/abstract.cfm?URI=ol-49-15-4214},

doi = {10.1364/OL.528029},

issn = {0146-9592, 1539-4794},

year  = {2024},

date = {2024-08-01},

urldate = {2024-10-30},

journal = {Optics Letters},

volume = {49},

number = {15},

pages = {4214},

abstract = {In this Letter, we propose and investigate a retroreflective optical 

 integrated sensing and communication (RO-ISAC) system using orthogonal 

 frequency division multiplexing (OFDM) and corner cube reflector 

 (CCR). To accurately model the reflected sensing channel of the 

 RO-ISAC system, both a point source model and an area source model are 

 proposed according to the two main types of light sources that are 

 widely used. Detailed theoretical and experimental results are 

 presented to verify the accuracy of the proposed channel models and 

 evaluate the communication and sensing performance of the considered 

 RO-ISAC system.},

keywords = {Integrated sensing and communication (ISAC), LRDC, Orthogonal frequency division multiplexing (OFDM)},

pubstate = {published},

tppubtype = {article}

}