| Unlike classical encryption systems that rely on computational complexity,quantum key distribution(QKD)technology is based on the basic principles of quantum mechanics and can resist attacks from high-speed computing machines such as quantum computers.With the vigorous development of QKD technology,the establishment of a QKD network has become a future development trend.In order to improve the resource utilization rate of QKD networks and reduce the networking cost,the integration of QKD and optical networks is an important research direction to promote the development of QKD networks.However,in the QKD optical networks based on space-time-frequency multidimensional multiplexing,it is the main challenge that the classical signal will cause serious noise interference to the weak quantum signal and affect the allocation of multi-dimensional resources.Focusing on the two major problems of noise interference and resource competition in multi-dimensional multiplexed QKD optical networks,this paper focuses on the research on the theoretical model of noise coupling and resource allocation schemes in multi-dimensional multiplexed QKD optical networks,establishes coupling theoretical models and proposes multi-dimensional resource distribution schemes,the main innovation work is as follows:(1)In the coupling theory,aiming at the influence of classical signal modulation factors on the performance of QKD system in co-fiber transmission without optical relay,a noise coupling theoretical model based on the influence of classical signal modulation factors is established to accurately calculate the noise power.In the current research on inter-core fourwave mixing and inter-core Raman scattering noise based on multi-core fiber,it is impossible to evaluate the influence of classical signal modulation factors on noise power.In order to accurately evaluate the inter-core noise generated by the classical signal on the quantum channel,this paper establishes the theoretical model of inter-core four-wave mixing and inter-core Raman scattering noise affected by the modulation frequency factor,and experimentally studies the effect of the classical signal modulation format and baud rate on the noise power.The results show that the model considering the modulation frequency can accurately calculate the noise power and extend the simulated safe transmission distance by about 15.2%compared with the existing model.When the classical signal power is constant,increasing the classical signal baud rate will reduce the secure key rate of QKD.(2)In coupling theory,aiming at the symmetry constraints of co-fiber transmission architecture and noise model with optical relay,a co-fiber transmission architecture and noise coupling theory based on asymmetric sending-or-not-sending QKD protocol(SNS-QKD)model is established to extend the transmission distance.Since the current long-distance co-fiber transmission architecture and theoretical model based on the twin-field protocol are constrained by factors such as symmetry in actual deployment,which limits the expansion of the transmission distance,this paper proposes an asymmetric SNS-QKD-based long-distance co-fiber transmission architecture with segmented flexibility,a theoretical model of four-wave mixing noise and Raman scattering noise under the influence of classical signals and optical amplifiers on quantum signals is proposed,and the asymmetric SNS-QKD secure key rate calculation formula under the influence of noise is derived,Finally,the performance of the architecture and the accuracy of the proposed noise theory model are evaluated through simulation and preliminary experiments.The results show that when the classical signal and quantum signal are transmitted in the same core,the transmission distance of BB84-QKD is longer than that of asymmetric SNS-QKD.When transmitted in different cores,the transmission distance of asymmetric SNS-QKD is longer.The maximum error between the proposed noise theoretical model and the experiment is not more than 2.6 dB.(3)In resource allocation,aiming at the noise interference problem of QKD in point to point transmission,a simultaneous transmission and synergistic transmission resource allocation scheme are respectively proposed to reduce noise interference.In the point-to-point co-fiber transmission system,in order to reduce noise interference,this paper proposes a core-wave length allocation scheme for simultaneous transmission and a corewavelength allocation scheme for synergistic transmission.The simultaneous transmission scheme can reduce the noise on the quantum channel,and the synergistic transmission scheme can reduce the noise on the classical channel and the quantum channel.The two types of resource allocation schemes are applicable to homogeneous multi-core optical fibers with any number of cores,and are applicable to both same-core transmission and different-core transmission of classical signals and quantum signals.Simulation and experimental results show that the proposed simultaneous transmission scheme has a noise suppression advantage of 57.54%compared with the comparison scheme.When the transmission distance is 1 km,compared with the comparison scheme,the proposed synergistic transmission scheme can improve the synergistic degree by about 0.57.(4)In resource allocation,aiming at the noise interference problem of QKD in point-to-multipoint transmission,a multi-dimensional resource allocation scheme with noise suppression and allocates multi-dimensional resources on demand is proposed to expend the number of quantum users.Aiming at the structure of switching nodes with different fiber types,this paper establishes a theoretical model of noise coupling based on switching nodes to accurately evaluate the impact of noise generated by classical signals in switching nodes on the performance of QKD,and proposes a low-noise,high-security,large-capacity parallel mobile fronthaul network architecture and time-spacefrequency multi-dimensional resource allocation scheme that can provide ondemand services and reduce power consumption can adapt to different service needs.Preliminary experiments evaluate the QKD performance of architectures under different requirements.The results show that the noise suppression scheme proposed in the architecture shows advantages in different service requirements,reducing the number of noise photons on the quantum channel by about 60%,and the proposed on-demand architecture can save up to 83.3%power consumption in the 7-core optical fiber,it can support the key requirements of 128 base stations,and the noise theoretical model and experimental error are not greater than 2.4 dB. |
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