A heuristic routing and wavelength assignment method for tidal traffic in multi-core fiber quantum secure metropolitan area network

Abstract

The application discloses a heuristic routing wavelength allocation method for tide flow in a multi-core optical fiber quantum secure metropolitan area network, and the method is suitable for a high-security and large-capacity metropolitan area network. Tide flow in the metropolitan area network leads to a decrease in resource utilization and uneven distribution of security key rates. The application proposes a service balancing type routing allocation method based on network load standard deviation minimization. In the heuristic method, classical services are dynamically selected to pass through the optimal transmission path, the uniformity of classical services and security keys in the network is improved, service congestion in high-service areas is avoided, and the utilization rate of wavelength resources is improved. In a dynamic scene, in order to reduce the noise influence of classical signals on quantum signals, the application proposes a heuristic noise suppression classical wavelength flexible allocation method based on priority differentiation. The method avoids system complexity and cost increase problems caused by frequent quantum channel reconstruction by fixing quantum channels, and simultaneously suppresses noise. The routing wavelength allocation method has important application prospects in the quantum secure metropolitan area network, and can improve the performance and security of the system.

Description

Technical Field

[0001] This invention relates to the field of quantum communication networks, and more particularly to the integration of a quantum key distribution system using multi-core optical fiber transmission with a metropolitan area network. This patent designs a heuristic routing wavelength allocation method for multi-core optical fiber quantum-secure metropolitan area networks. This technology aims to solve the problems of low resource utilization, uneven distribution of secure key rates, and interference of classical signals with quantum signals caused by tidal traffic in metropolitan area networks, thereby improving the performance and security of quantum-secure metropolitan area networks. Background Technology

[0002] The three laws of quantum mechanics guarantee that quantum key distribution (QKD) can be used to improve the security of metropolitan area networks (MANs). Integrating a QKD system with a MAN is called a quantum-secure MAN, which saves fiber optic cables compared to laying separate fiber optic cables for a QKD system. Single-core fiber capacity is close to the Shannon limit and cannot meet the explosive growth of data volume in the future. Multi-core fiber, as a new type of fiber, can achieve a significant increase in network transmission bandwidth. Using multi-core fiber as the transmission medium for quantum-secure MANs can significantly improve transmission capacity.

[0003] In quantum-secure metropolitan area networks (MANs), the uneven distribution of users leads to uneven distribution of network traffic, a phenomenon known as tidal traffic. This results in higher congestion rates in high-traffic areas, while some channel resources remain idle in low-traffic areas, leading to decreased network resource utilization. Furthermore, the uneven distribution of classical traffic results in uneven key distribution in QKD systems. Routing allocation methods for tidal traffic in MANs primarily focus on reducing network congestion rates. However, to ensure the quality of service for each user, the balance between network traffic and keys must also be considered. Therefore, achieving balanced integration of network traffic is one of the main challenges facing quantum-secure MANs.

[0004] Furthermore, when classical and quantum signals are transmitted in the same multi-core optical fiber, the weak quantum signal (typically below -80dBm) is interfered with by noise (spontaneous Raman scattering noise, four-wave mixing noise, and inter-core crosstalk noise) generated by the high-power classical signal (approximately 0dBm). In the converged transmission of QKD systems and classical optical networks, the time-varying noise generated by the dynamic arrival of classical services renders resource allocation methods designed for static scenarios inapplicable. Utilizing wavelength fragments generated by classical signals to transmit quantum signals increases the number of quantum signal reconstructions, which is complex for quantum devices. Therefore, how to rationally allocate wavelengths for dynamic services to achieve noise suppression without increasing the complexity of quantum devices is the second major challenge facing quantum-safe metropolitan area networks.

[0005] In summary, the main objectives of quantum-safe metropolitan area networks are to design a routing allocation method for balancing network services and to flexibly allocate classical signals to suppress noise generated by classical signals when the quantum channel is fixed. Summary of the Invention

[0006] This patent addresses the application scenario of QKD system integration with metropolitan optical networks, primarily considering how to achieve balanced classical services within the network and suppress the noise impact of classical signals on quantum signals. It includes two key technical points: 1. A service-balanced routing allocation method based on minimizing the network load standard deviation; 2. A flexible classical wavelength allocation method based on priority-based noise suppression.

[0007] To address the first key technical point, namely the problem of balancing tidal traffic in converged networks, a service-balanced routing allocation method based on minimizing the standard deviation of network load is proposed. This heuristic routing allocation method is described as follows:

[0008] Step 1: When a classic service arrives dynamically in the network, obtain the source node s and destination node d of the service. Use the minimum hop count algorithm to calculate k paths (l1, l2, ..., l...) between the source node s and the destination node d. k Sort by hop count in ascending order, and let t = 1, where t represents the t-th optional path;

[0009] Step 2: Obtain the j-th link L in the network j The number of wavelengths N occupied by classic services on (j = 1, 2, ..., m, where m is the number of links in the network) j When l t Links in the network and links in the network j When they are the same, N j +1 to set M, otherwise add to set N. j Add the set M and calculate the standard deviation Std of set M. i , Std t Add to collection Std;

[0010] Step 3: Reassign the value of t+1 to t. If t≤k, repeat step 2; otherwise, execute step 4.

[0011] Step 4: Obtain the minimum value Std in the set Std. min The corresponding path l min As the final path for the business, min represents the number of the optional path that minimizes the standard deviation of network load.

[0012] Regarding the second technical point, namely the noise suppression problem of classical signals on quantum signals during co-fiber transmission, a noise suppression method based on priority-based flexible allocation of classical wavelengths is proposed. The specific explanation of this heuristic method is as follows:

[0013] When a classic service arrives dynamically, the service path is obtained using the method described in Technical Point 1. The number of quantum fiber cores is determined based on the required number of quantum channels. The required quantum channels are fixedly allocated to the quantum fiber cores on each link of the path. Then, a priority-based noise suppression classical wavelength flexible allocation method is used to allocate wavelengths for the classic service. The characteristic is that the number of fiber cores in the multi-core fiber is p, and the number of available wavelengths in each fiber core is n, where i represents the i-th fiber core, j represents the available wavelength number in the fiber core, and CH ij PR represents the channel corresponding to the j-th wavelength of fiber core i. ij It is a constant that represents the priority of the j-th wavelength channel in fiber core i being occupied by classical signals. The smaller the value, the higher the priority. Wavelength allocation includes the following steps:

[0014] Step 1: Determine the number of quantum channels N required between each pair of nodes. q Determine the required set of quantum fiber cores Q (Q←{Q1, Q2, ..., Q...). m}, where m is the number of quantum cores, Q i (representing the i-th quantum fiber core), initialize Q ch Represents the set of allocated quantum channels;

[0015] Step Two: When At that time, PR ij =1,

[0016] Step 3: Set the first element in Q to the current quantum fiber core, with the core number c, and set w = 1, where w represents the next quantum channel wavelength number to be assigned;

[0017] Step 4: Set the w-th wavelength in fiber core c as the quantum channel, and set CH cw Add to set Q ch PR iw =PR iw +1, where i is the adjacent core of core c, PR cj =PR cj +1, where j∈[w+1,n];

[0018] Step 5: If Q ch The number of elements in is equal to N q Execute step six, if Q ch The number of elements in is less than N qw = w + 1, repeat step four. If there is no free channel in fiber core c, delete element c from Q and execute step three.

[0019] Step 6: If there are N or more idle channels in fiber core c, set up N guard channels adjacent to the allocated quantum channels to reduce core noise. If the number of idle channels is less than N, set all idle channels as guard channels.

[0020] With channel priority allocation complete, when classic services arrive, they will first be prioritized in the PR (Priority Channel). ij Searching for available channels among channels with PR = 1, when PR ij When there is no available channel in the channel with =1, in PR ij The search continues in channels with a value of 2, and so on. If the requirement cannot be met in any of the channels, the service is blocked.

[0021] The method described in this patent can be applied to networks integrating QKD systems using multi-core optical fiber transmission with metropolitan area networks (MANs). It offers advantages such as balanced security key rates for classic network services, flexible allocation of classic channels, low requirements for quantum devices, and minimal impact from noise on quantum channels. This method lays the foundation for improving the security and transmission capacity of metropolitan area networks. Attached Figure Description

[0022] Figure 1 Figure (a) and Figure (b) are schematic diagrams of the heuristic routing wavelength allocation method described in this method.

[0023] Figure 2 The diagram shows the routing results of the service-balanced routing allocation method based on minimizing the standard deviation of network load described in this paper in the NSFNET network. The path between the source node 5 and the destination node 7 is calculated as an example.

[0024] Figure 3 The image shows the wavelength priority allocation results of the wavelength flexible allocation method based on noise impact in a 7-core multi-core optical fiber. Detailed Implementation

[0025] To make the objectives, technical methods, and advantages of this invention clearer, the following description is provided in conjunction with the appendix. Figure 2 Appendix Figure 3 The present invention will be further described in detail below. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0026] The routing wavelength allocation method proposed in this patent is applicable to transmission networks that integrate QKD systems and metropolitan area networks, and can be used as shown in the appendix. Figure 2The network topology diagram shown simulates a quantum-secure metropolitan area network (MAN). The network has 14 nodes and 21 links, with nodes divided into residential area nodes (high traffic on weekdays) and office area nodes (low traffic on weekdays). The service-balanced routing allocation method based on minimizing the network load standard deviation proposed in this invention is used to select routes for source node 5 and destination node 7. The final path is shown in the attached diagram. Figure 2 The example above illustrates the path allocation method proposed in this invention. It allows for the use of wavelength resources in low-traffic areas to schedule services in high-traffic areas during tidal traffic events, thereby reducing congestion rates in high-traffic areas, improving network resource utilization, and balancing network traffic.

[0027] In the classical wavelength flexible allocation method for noise suppression based on priority differentiation proposed in this patent, multi-core optical fibers can be used as shown in the attached figure. Figure 3 (1) As shown in the diagram, a 7-core optical fiber, assuming each core has 8 usable wavelengths and each pair of nodes requires 10 quantum channels, then two quantum cores are needed. Figure 3 (1) A diagram showing the allocation of classical and quantum fiber cores in a 7-core optical fiber, with quantum fiber cores being cores 7 and 6. When no quantum channel is allocated, all wavelengths are preferentially set to 1, as shown in the attached diagram. Figure 3 (2a) In quantum core 7, wavelength 1 is assigned as a quantum channel, and the priority of wavelength 1 in adjacent cores (cores 4, 5, 6) and wavelengths [2, 8] in core 7 is reduced, as shown in the appendix. Figure 3 (2b) At this point, the number of quantum channels already allocated is less than 10. Continue allocating wavelength 2 as a quantum channel in quantum core 7, and lowering the priority of wavelength 2 in adjacent cores of core 7, as shown in the appendix. Figure 3 (2c), and so on, all wavelengths in fiber core 7 are allocated as quantum channels (as shown in the appendix). Figure 3 At step (2d), the number of allocated quantum channels is 8. Continue with the same steps in quantum core 6, where the adjacent quantum cores are cores 3 and 4 (core 7 is not considered) until the number of allocated quantum channels is 10, as shown in the appendix. Figure 3 (2e). After allocating the quantum channels, wavelengths 3 and 4 in quantum fiber core 6 are used as guard channels to reduce noise within the core. Classical services cannot occupy these guard channels. At this point, the priority allocation of wavelengths available for classical signals within the 7-core fiber is complete. When a service arrives, it is selected according to wavelength priority. As can be seen from the above embodiments, the wavelength allocation method proposed in this patent has advantages such as noise suppression and flexibility in meeting requirements.

Claims

1. A heuristic routing wavelength allocation method for tidal traffic in multi-core fiber quantum-secure metropolitan area networks, characterized in that, The method described above can achieve the goals of balancing network traffic, reducing traffic congestion rate, balancing the security key rate of quantum key distribution (QKD) systems, and suppressing the noise impact of classical signals on quantum signals during co-fiber transmission in converged networks. The main contents include: A. A service-balanced routing method based on minimizing the standard deviation of network load is proposed. This method is a heuristic approach. Its main idea is to calculate multiple optional paths between origin and destination nodes using the minimum hop count algorithm, and select the path with the smallest standard deviation of network load as the final path using the standard deviation of network load brought by each optional path as the standard. This method is an adaptive routing method, which can reduce the service blocking rate compared with the fixed routing method. B. A novel method for noise suppression based on priority is proposed, which is a heuristic approach. In this method, quantum channels are fixedly allocated. This reconfiguration-free approach has low requirements for the deployment cost of quantum devices and networks. By measuring the noise impact on the allocated quantum signals, the reserved classical channels are divided into different priorities. The higher the priority, the smaller the noise impact of the channel on the quantum channel, thereby achieving the purpose of noise suppression.

2. The method as described in claim 1, characterized in that, The service-balanced routing allocation method based on minimizing the standard deviation of network load can achieve the goals of balancing network tidal traffic, reducing service congestion rate, and balancing the security key rate of the QKD system. This method includes the following steps: S1. When a classic service arrives dynamically in the network, the source node s and destination node d of the service are obtained. The minimum hop count algorithm is used to calculate k paths (l1, l2, ..., l...) between the source node s and the destination node d. k Sort by hop count in ascending order, and let t = 1, where t represents the t-th optional path; S2, Obtain the j-th link L in the network. j The number of wavelengths N occupied by classic services on (j = 1, 2, ..., m, where m is the number of links in the network) j When l t Links in the network and links in the network j When they are the same, N j +1 and add it to set M; otherwise, add it to set N. j Add the set M and calculate the standard deviation Std of set M. t , Std t Add to collection Std; S3. Reassign the value of t+1 to t. If t≤k, repeat S2; otherwise, execute S4. S4. Find the minimum value Std in set Std. min The corresponding path l min As the final path for the business, min represents the number of the optional path that minimizes the standard deviation of network load.

3. The method as described in claims 1 and 2, characterized in that, The classical wavelength flexible allocation method based on priority-based noise suppression can suppress the noise impact of classical signals on quantum signals. When classical services arrive dynamically, the service path is obtained using the method described in claim 2. The number of quantum fiber cores is determined according to the required number of quantum channels. The required quantum channels are fixedly allocated to the quantum fiber cores on each link of the path. Then, the classical wavelength flexible allocation method based on priority-based noise suppression is used to allocate wavelengths for classical services. The number of fiber cores in the multi-core fiber is p, and the number of available wavelengths in each fiber core is n, where i represents the i-th fiber core, j represents the number of available wavelengths in the fiber core, and CH ij PR represents the channel corresponding to the j-th wavelength in fiber core i. ij It is a constant that represents the priority of the j-th wavelength channel in fiber core i being occupied by classical signals. The smaller the value, the higher the priority. Wavelength allocation includes the following steps: S1. Based on the number of quantum channels N required between each pair of nodes q Determine the required set of quantum fiber cores Q(Q←{Q1,Q2,…,Q) m }, where m is the number of quantum cores, Q i (representing the i-th quantum fiber core), initialize Q ch Represents the set of allocated quantum channels; S2, when hour, The first element in S3 and Q is set to the current quantum fiber core, with the core number being c. w = 1 is set, where w represents the next quantum channel wavelength number to be assigned. S4. Set the w-th wavelength in fiber core c as the quantum channel, and set CH cw Add to set Q ch PR iw =PR iw +1, where i is the adjacent core of core c, PR cj =PR cj +1, where j∈[w+1,n]; S5, if Q ch The number of elements in is equal to N q Execute S6, if Q ch The number of elements in is less than N q w = w + 1, repeat S4. If there is no free channel in fiber core c, delete element c from Q and execute S3. S6. If there are N or more idle channels in the fiber core c, set up N guard channels adjacent to the allocated quantum channels to reduce the noise in the core. If the number of idle channels is less than N, set all idle channels as guard channels. With channel priority allocation complete, when classic services arrive, they will first be prioritized in the PR (Priority Channel). ij Searching for available channels in channels with PR = 1, when PR ij When there is no available channel in the channel with =1, in PR ij The service is searched in channels with a capacity of 2, and so on. If none of the channels can meet the requirements, the service is blocked.

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