Resource allocation method for sensing inter-core crosstalk in multi-core multimode optical fiber elastic optical network

Abstract

The invention relates to a resource allocation method for sensing inter-core crosstalk in a multi-core multimode optical fiber elastic optical network, which is applied to the field of optical communication. According to the method, the inter-core and inter-mode crosstalk problems and the spectrum fragmentation problem existing in the elastic optical network are considered, and resource allocation is carried out on the incoming service request. Firstly, a Dijkstra algorithm is used for calculating a path with the shortest distance for a service request to serve as a transmission path, a modulation format is selected according to the distance length, and the frequency slot number needed by the service is calculated. Secondly, selecting a fiber core and a mode group, and screening available frequency spectrum blocks by adopting an inter-mode crosstalk avoiding and inter-core crosstalk sensing mode; and finally, designing a fragment coefficient calculation formula by considering frequency domain and time domain fragments, and selecting proper frequency spectrum blocks for allocation according to the fragment coefficient. According to the resource allocation method provided by the invention, the appropriate frequency spectrum block can be selected according to the fragment coefficient of the frequency spectrum block in the path on the premise of satisfying the crosstalk constraint, and the utilization rate of the frequency spectrum resource is improved while the service blocking rate is reduced.

Description

Technical Field

[0001] The present invention relates to the field of optical communications, and in particular to spectrum resource allocation in a space-division multiplexing elastic optical network, and specifically to a resource allocation method for core-to-core crosstalk perception in a multi-core multimode optical fiber elastic optical network. Background Art

[0002] With the rapid development of communication technology and the continuous innovation of various network services, the scale of network infrastructure continues to expand, and the rapid development of mobile Internet and Internet of Things has become one of the prominent features of today's society. In this development context, the bandwidth resources required by optical networks are growing, resulting in huge bandwidth capacity requirements for communication networks. In traditional wavelength division multiplexing (WDM) optical networks, fixed-size wavelengths are usually used as the minimum granularity to allocate service bandwidth. Even if the bandwidth required by the incoming service request is less than one grid bandwidth, a complete grid bandwidth resource needs to be allocated, resulting in a waste of bandwidth resources. As an emerging optical communication network architecture, elastic optical networks use orthogonal frequency division multiplexing (OFDM) technology to significantly improve transmission capacity. However, with the increasing demand for traffic, elastic optical networks with single-core fibers are gradually approaching their physical limits. Therefore, space division multiplexing elastic optical networks (SDM-EONs) have become one of the current research hotspots in the field of optical communications due to their advantages in spectrum utilization, transmission capacity and flexibility.

[0003] Multi-core multi-mode fiber (MC-MMF) combines the characteristics of multi-core and multi-mode fibers, greatly increasing the transmission capacity and flexibility of optical networks. However, it also introduces the problems of crosstalk management between cores and modes and fragmentation, making the resource allocation problem more complicated. Therefore, developing an effective spectrum allocation algorithm to achieve efficient and low-interference signal transmission in multi-core multi-mode fibers is one of the current research focuses.

[0004] In the space-division multiplexing elastic optical network of multi-core multi-mode optical fiber, the management of crosstalk between cores and modes and the problem of fragmentation are important issues that affect network performance and resource utilization. More and more scholars pay attention to and work hard to improve these problems. In the problem of crosstalk management between cores and modes, there are generally two ways: crosstalk avoidance and crosstalk perception. In the problem of spectrum fragmentation, there are mainly two ways: active spectrum fragmentation and avoiding spectrum fragmentation. Active spectrum fragmentation takes a lot of time, so most research tends to avoid the generation of spectrum fragmentation. In the literature [1] (BC Chatterjee, A. Wadud, I. Ahmed and E. Oki. Priority-Based Inter-Core and Inter-Mode Crosstalk-Avoided Resource Allocation for Spectrally-Spatially Elastic Optical Networks [J]. IEEE / ACM Transactions on Networking, 2021, 29 (4). 1634-1647.), a core, mode and spectrum allocation scheme based on priority crosstalk avoidance is proposed. By creating different core and mode groups, assigning priorities to each group, and selecting cores and modes according to their priority to serve lightpath requests, the resource utilization of the network is improved. In the literature [2] (Yaghoub Khorasani, Akbar Ghaffarpour Rahbar, Mohammad Jafari-Beyrami. A novel two-dimensional metric for fragmentation evaluation in elastic optical networks [J]. Computer Networks, 2022, 216.), a novel two-dimensional fragmentation evaluation metric for elastic optical networks is proposed. This metric quantifies the amount of fragmentation in a link by combining the frequency slots that can be used for subsequent allocation and the frequency slots that cannot be used for subsequent allocation. Based on this metric, a new routing, spectrum and core allocation algorithm (Golden-RSCA) is proposed to solve the spectrum fragmentation problem.Both of the above documents discuss resource allocation methods in space-division multiplexing elastic optical networks. However, document [1] does not consider the spectrum fragmentation problem in space-division multiplexing elastic optical networks, and adopts a method to avoid both inter-core and inter-mode crosstalk. This will result in some frequency slots that do not exceed the crosstalk threshold being unable to be used for spectrum allocation, resulting in a waste of spectrum resources and reduced spectrum utilization. Document [2] is a resource allocation method based on multi-core optical fibers, which considers the impact of frequency domain fragmentation on service transmission. However, this document does not further consider the problem of time domain fragmentation, nor does it consider the impact of inter-core crosstalk.

[0005] Therefore, according to the existing resource allocation method considering the fragmentation problem in the space-division multiplexing elastic optical network, the present invention proposes a resource allocation method for core-to-core crosstalk perception in a multi-core multimode optical fiber elastic optical network. The method adopts core-to-core crosstalk perception and mode-to-mode crosstalk avoidance in the multi-core multimode optical fiber to meet the crosstalk constraint, and designs a calculation formula for the fragmentation coefficient on this premise, selects the appropriate spectrum block for the service request according to the fragmentation coefficient of each available spectrum block, and improves the resource utilization while ensuring the bandwidth blocking rate performance. Summary of the invention

[0006] In view of this, the present invention proposes a resource allocation method for core-to-core crosstalk perception in a multi-core multimode optical fiber elastic optical network based on consideration of core-to-core and inter-mode crosstalk and spectrum fragmentation. The method is characterized in that, on the premise of using core-to-core crosstalk perception and inter-mode crosstalk avoidance to meet the crosstalk constraint, the spectrum fragmentation problem existing in the network is taken into account, and resource utilization is improved while ensuring bandwidth blocking rate performance.

[0007] In order to achieve the above object, the present invention provides the following technical solution, the specific steps are:

[0008] S1. Initialize the network topology and spectrum resource status of each link, where the network topology structure is G(V, E, C, M, F), V is the node set in the network, E is the link set in the network, C is the core set, M is the mode set, and F is the frequency slot set corresponding to each link;

[0009] S2. Wait for the arrival of a service request r(s, d, B, t), where s is the source node of the service request, d is the destination node of the service request, B is the rate of the service request, and t is the duration of the service request;

[0010] S3. Prioritize the fiber core and mode groups to obtain the priority queue H of the fiber core and mode groups;

[0011] S4. Use Dijkstra algorithm to search for the shortest path L between the source and destination nodes for the service request r r , and L r As the service request transmission path, k is the number of hops in the path, are the links in the path;

[0012] S5. According to the transmission distance of the selected transmission path, obtain the available modulation format range, select the highest modulation format, and calculate the number of frequency slots FS required for the service request r r Since the transmission rate of the optical path request type is within a certain range and the available modulation formats are fixed to 6, the required number of frequency slots FS r In the discrete value set FS = {d1, d2, ···, d sumd}, where sumd is the total number of discrete types of frequency slots required for the service request, and the set is sorted in ascending order;

[0013] S6. Establish the core and mode group used by the service request r, and select the core and mode group in the priority queue H obtained in S3 in order. If all the cores and mode groups in H are traversed, the service request is blocked;

[0014] S7. Obtain all idle spectrum blocks on the service transmission path based on the selected fiber core and mode group and store them in the set SB free If the set SB free If it is empty, jump to S6, and use the method of core-to-core crosstalk perception and mode-to-mode crosstalk avoidance to filter out the available spectrum blocks in these idle spectrum blocks and store them in the set SB usable If the set SB usable If it is empty, jump to S6;

[0015] S8. Calculate SB usable The fragmentation coefficient (FC) of each available spectrum block in the , and the fragmentation coefficient is arranged from low to high, and stored in the candidate spectrum block set SB cand , select SB cand The first spectrum block is allocated;

[0016] Further, in step S3, the priority division of the fiber core and mode group specifically includes:

[0017] S301. Consider each fiber core and its corresponding mode as a virtual node on an auxiliary graph. Take a seven-core six-mode optical fiber as an example. The seven fiber cores are numbered: c1, c2, c3, c4, c5, c6, c7, and the six modes are numbered: m1, m2, m3, m4, m5, m6. There are 42 combinations of fiber cores and mode groups, that is, the number of nodes in the auxiliary graph is 42. The fiber core and mode group c1m1 is recorded as node 1, c1m2 is recorded as node 2, and so on.

[0018] S302. Determine the connection relationship between nodes according to the crosstalk effect between each fiber core and mode group. If there is crosstalk effect, it is determined that the two virtual nodes are connected. The crosstalk effect evaluation criteria are as follows: ① If the same mode between adjacent fiber cores uses the same frequency slot, it will produce inter-core crosstalk effect, and the inter-core crosstalk effect between non-adjacent fiber cores can be ignored; ② If adjacent modes in the same fiber core use the same frequency slot, it will produce inter-mode crosstalk effect, and the inter-mode crosstalk effect between non-adjacent modes can be ignored;

[0019] S303. Draw an auxiliary graph consisting of each node through the obtained connection relationship;

[0020] S304. Calculate the degree of each node according to the auxiliary undirected graph obtained in S303;

[0021] S305. Sort the degree of each node in ascending order, and then add each node to the priority queue H in turn, with the node with the highest priority at the head of the queue and the node with the lowest priority at the tail of the queue;

[0022] Further, in step S7, the process of selecting available spectrum blocks by using the inter-core crosstalk sensing and inter-mode crosstalk avoidance method specifically includes:

[0023] S701. For idle spectrum block set SB free All spectrum blocks in , using the mode-interference avoidance method, for the idle spectrum block set SB free For any frequency slot in the fiber core, according to the mode in which it is located, it searches and determines whether the frequency slot with the same serial number on the adjacent mode in the same fiber core is occupied. If it is occupied, it is removed from the idle spectrum block set SB. free , and in this way the spectrum block set SB that satisfies the inter-mode crosstalk constraint is calculated. m ;

[0024] S702. Spectrum block set SB that meets the inter-mode crosstalk constraint m Calculate the inter-core crosstalk value for all spectrum blocks in the

[0025] The calculation formula for core-to-core crosstalk is defined as follows:

[0026]

[0027] In formula (1) and formula (2), The working fiber core c selected for the service request and the adjacent fiber core c′ occupy the same frequency slot f i The resulting crosstalk value, Indicates the transmission path L of the service request r r Upper frequency gap f i The total crosstalk value is represents each link on the transmission path of the service request r, For Link The length, N c Indicates that it is adjacent to the fiber core c and occupies the frequency slot f i The core set of , h is the crosstalk increment per unit length, which is defined as shown in formula (3):

[0028]

[0029] In formula (3), B r is the bending radius, β is the mode propagation constant and β=k×n eff , n eff The effective refractive index of the mode m selected for the service request is k = 2π / λ, where k is the wave number, λ is the wavelength of light in vacuum, and γ c,c′ is the core distance between core c and core c′, δ c,c′ is the coupling coefficient between core c and core c′;

[0030] S703. According to the crosstalk value generated by the frequency slot used by the existing service request in the network to the pre-allocated frequency slot of the current incoming service request, and the crosstalk value generated by the pre-allocated frequency slot of the new incoming service request interfering with the frequency slot used by other existing service requests, the core-to-core crosstalk perception method is adopted, that is, only when the crosstalk values ​​of both are lower than the preset crosstalk threshold, the core-to-core crosstalk constraint is met, thereby screening out SB m The available spectrum blocks in the set SB usable middle;

[0031] Further, in step S8, the calculation step of the fragmentation coefficient FC includes:

[0032] S801. For set SB usable For each available spectrum block in the , assume that the service request selects the spectrum block and allocates it on the left side. The size of the additional spectrum fragment generated after allocation is expressed as GAP i represents, i represents the sequential number of each additional spectrum fragment;

[0033] S802. Calculate each GAP i The applicable allocation weight a i and does not apply the allocation weight b i , as shown in formula (4)(5):

[0034]

[0035] Among them, 1 {·} is an indicator function, which means it is 1 when the condition is met, otherwise it is 0; prob m Represents the probability of the arrival of the mth service request.

[0036] S803. Calculate SB usable Each available spectrum block in the link The frequency domain fragmentation coefficient on Its calculation is shown in formula (6):

[0037]

[0038] Among them, w a Assign a fitness weight to the future, w b Assign unsuitability weights to the future, w a 、w b They are defined by formula (7) and formula (8) respectively:

[0039]

[0040] Where |GAP| is the total number of additional spectrum fragments generated after the assumed allocation, and q is a very small positive value that is not 0, in order to prevent the denominator from being 0.

[0041] S804. Calculate the set SB usable The time domain fragmentation coefficient of each available spectrum block in is used to find the spectrum block whose remaining time best matches the requested duration, and the remaining time ts requested on the left side of the spectrum block is left , spectrum block right side request remaining time ts right , and the duration t of the service request r r Decide;

[0042] In the link The temporal fragmentation coefficient on The calculation is as follows:

[0043]

[0044] Among them, ts left =prev end -t cur ,prev end The end time of the service corresponding to the first non-idle frequency slot on the left side of the current idle spectrum block. If the spectrum block is located at the head, ts left Take 0, t cur is the real time; ts right =next end -t cur , next end The end time of the service corresponding to the first non-idle frequency slot on the right side of the current idle spectrum block. If the spectrum block is at the end, ts right Take 0;

[0045] S805. Calculate the fragmentation coefficient (FC i ), which comprehensively considers the impact of frequency domain fragmentation and time domain fragmentation; fragmentation coefficient FC i The calculation formula is formula (10):

[0046]

[0047] The beneficial effects of the present invention are:

[0048] A resource allocation method based on core-to-core crosstalk perception in multi-core multimode fiber elastic optical network is proposed. When allocating routing, core, mode and spectrum resources for service requests, the core-to-mode crosstalk and spectrum fragmentation problems are considered. In the routing and modulation format selection stage, the algorithm uses the Dijkstra algorithm to search for the shortest path between the source and destination nodes as the transmission path for the service request, and establishes the corresponding modulation format according to the distance of the selected transmission path, and calculates the required number of frequency slots; in the core and mode selection stage, the core and mode groups are prioritized, and the core and mode groups with less interference to other cores and mode groups are preferentially selected; in the spectrum allocation stage, the fragmentation coefficient calculation formula is designed to select the most appropriate available spectrum block according to the size of the fragmentation coefficient. Under the premise of using the inter-core crosstalk perception and inter-mode crosstalk avoidance method to meet the crosstalk constraints, the resource allocation method flexibly selects appropriate spectrum resources according to the fragmentation degree of link spectrum resources, which can reduce the waste of spectrum resources and improve resource utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0050] Figure 1 A diagram showing the relationship between the cores and modes in the seven-core six-mode optical fiber used in the present invention and a schematic diagram showing the crosstalk between the cores and modes;

[0051] Figure 2 The overall flow chart of the method proposed by the present invention;

[0052] Figure 3 Example diagram of spectrum block selection for use with the present invention. Specific implementation plan

[0053] The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] Attached Figure 1This is a diagram showing the relationship between the cores and modes in the seven-core six-mode optical fiber used in the present invention, as well as a schematic diagram showing the crosstalk between the cores and the modes. Figure 1 (a) are the adjacent relationships between the seven fiber cores and the adjacent relationships between the six modes in the fiber core. Figure 1 (b) shows the determination of core-to-core and mode-to-mode crosstalk in four different situations: region ① is when the same mode is used between adjacent cores; region ② is when adjacent modes are used within the same core; region ③ is when different modes are used between adjacent cores; and region ④ is when adjacent modes are used between non-adjacent cores. According to the determination criteria for core-to-core and mode-to-mode crosstalk, it can be seen that in region ①, since core c1 and core c2 are adjacent and use the same mode m1, there is core-to-core crosstalk between the same frequency slots used in requests r1 and r4. In region ②, due to the Requests r1 and r3 both use the fiber core c1, and use the adjacent modes m1 and m2 respectively, so there is inter-mode crosstalk between the same frequency slots used. Requests r5 and r6 in area ③ use the adjacent fiber cores c2 and c3, but because different modes m1 and m2 are used, the crosstalk effect can be ignored. Requests r2 and r6 in area ④ use non-adjacent fiber cores c1 and c3, and use different modes m1 and m2, so the crosstalk effect can also be ignored. Therefore, the areas with crosstalk effect are areas ① and ②.

[0055] Attached Figure 2 The overall flow chart of the resource allocation method for core-to-core crosstalk perception in a multi-core multimode optical fiber elastic optical network is described in detail below:

[0056] Input: network topology G(V,E,C,M,F), service request r(s,d,B,t)

[0057] Output: Business transmission results

[0058] Step 1: Initialize the network topology and spectrum resource status of each link;

[0059] Step 2: A service request r(s, d, B, t) arrives, where s is the source node of the service request, d is the destination node of the service request, B is the rate of the service request, and t is the duration of the service request;

[0060] Step 3: Consider each fiber core and mode group as a node, and establish a connection relationship between each node based on the crosstalk influence degree: the same mode of adjacent fiber cores will generate inter-core crosstalk when in the same frequency slot, so there is a connection relationship; adjacent modes of the same fiber core will generate inter-mode crosstalk when using the same frequency slot, so there is a connection relationship. Draw an auxiliary graph based on the connection relationship, calculate and sort the node degrees in ascending order, and add the nodes to queue H according to priority, with the highest priority at the head of the queue;

[0061] Step 4: Use Dijkstra algorithm to search for the shortest path L for service request r r As a transmission path;

[0062] Step 5: Determine the modulation format of the service request according to the distance length of the selected transmission path;

[0063] Step 6: Calculate the number of frequency slots FS required for the service request based on the transmission path length and the selected modulation format r ;

[0064] Step 7: Select the first fiber core in the priority queue H, mode group h=1, and jump to step 9;

[0065] Step 8: Determine whether h is equal to |H| at this time. If so, jump to step 15. If not, h=h+1.

[0066] Step 9: According to the selected fiber core and mode group h, the number of all frequency slots on the transmission path ≥ FS r The idle spectrum blocks are stored in the idle spectrum block set SB free middle;

[0067] Step 10: Determine the idle spectrum block set SB free Is it empty? If it is empty, jump to step 8; if it is not empty, jump to step 11;

[0068] Step 11: Use the method of core-to-core crosstalk perception and mode-to-mode crosstalk avoidance to screen out the idle spectrum block set SB free and add these spectrum blocks to the available spectrum block set SB usable middle;

[0069] Step 12: Determine the idle spectrum block set SB usable Is it empty? If it is empty, jump to step 8; if it is not empty, jump to step 13;

[0070] Step 13: Calculate the idle spectrum block set SB usable The fragment coefficients FC of each spectrum block in the spectral block are sorted in ascending order according to the fragment coefficients and stored in the candidate spectrum block set SB cand middle;

[0071] Step 14: Select a candidate spectrum block set SB cand Allocate the first spectrum block in

[0072] Step 15: Business request blocking;

[0073] Step 16: Business transmission is successfully established;

[0074] Step 17: Output the transmission result;

[0075] Step 18: The algorithm ends.

[0076] Attached Figure 3 This is an example diagram of spectrum block selection used in the present invention. Assume that the number of frequency slots required for the incoming service request is 3FS, the duration is 3s, and the selected transmission path passes through three links Link1-Link2-Link3. After screening according to the principle of avoiding crosstalk between cores and modes, available spectrum blocks SB1 (frequency slot indexes 3 to 5) and available spectrum blocks SB2 (frequency slot indexes 10 to 16) are obtained. The value set of the number of frequency slots required for all services is FS = {2, 3, 4, 5, 6}, and their arrival probabilities are respectively Take q=1. If SB2 is pre-selected for transmission, 6 additional spectrum fragments will be generated, namely, spectrum fragments of size 2 with indices 8 to 9 and size 4 with indices 13 to 16 on Link1, spectrum fragments of size 5 with indices 13 to 17 on Link2, spectrum fragments of size 1 with indices 9 and size 6 with indices 13 to 18 on Link3. Taking the calculation of the two spectrum fragments GAP1 and GAP2 of SB2 on Link1 as an example, the size of GAP1 is 2. Since only 2FS in the value set FS of the number of frequency slots is equal to the size of GAP1, and the rest of the required frequency slots are greater than 2FS, the applicable weight corresponding to GAP1 for future allocation can be calculated. and future allocations not applicable to weights The size of GAP2 is 4. Similarly, the corresponding value of GAP2 is calculated. Therefore, we can know the total applicable coefficient of SB2 on Link1 Frequency Domain Fragmentation Coefficient Temporal fragmentation coefficient Therefore, the fragmentation coefficient of SB2 on Link1 is about 0.921. Similarly, the fragmentation coefficients of SB2 on Link2 and Link3 are 0.039 and 0.275 respectively. Therefore, the fragmentation coefficient of SB2 is FC 2 ≈1.235, and similarly, the fragmentation coefficient of SB1 is FC 1 ≈5.89, so SB2 with a small fragmentation coefficient is selected for allocation.

[0077] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A resource allocation method for core-to-core crosstalk awareness in a multi-core multimode optical fiber elastic optical network, characterized in that: The following steps are involved: S1. Initialize the network topology and spectrum resource status of each link; S2. Wait for the arrival of a service request r(s, d, B, t), where s is the source node of the service request, d is the destination node of the service request, B is the rate of the service request, and t is the duration of the service request; S3. Prioritize the fiber core and mode groups to obtain the priority queue H of the fiber core and mode groups; S4. Use Dijkstra algorithm to search for the shortest path L between the source and destination nodes for the service request r r , and L r As the service request transmission path, k is the number of hops in the path, are the links in the path; S5. According to the transmission distance of the selected transmission path, obtain the available modulation format range, select the highest modulation format, and calculate the number of frequency slots FS required for the service request r r ; S6. Establish the core and mode group used by the service request r, and select the core and mode group in the priority queue H obtained in S3 in order. If all the cores and mode groups in H are traversed, the service request is blocked; S7. Calculate all idle spectrum blocks on the selected core and mode of the service transmission path according to the core and mode group determined in S6, and store them in the set SB free If the set SB free If it is empty, jump to S6, and use the method of core-to-core crosstalk perception and mode-to-mode crosstalk avoidance to filter out the available spectrum blocks in these idle spectrum blocks and store them in the set SB usable If the set SB usable If it is empty, jump to S6; S8. Calculate SB usable The fragmentation coefficient (FC) of each available spectrum block in the , and the fragmentation coefficient is arranged from low to high, and stored in the candidate spectrum block set SB cand , select SB cand The first spectrum block in is allocated.

2. The resource allocation method for core-to-core crosstalk awareness in a multi-core multimode optical fiber elastic optical network according to claim 1, characterized in that: In step S3, the specific method is: S301. Treat each fiber core and its corresponding mode as a virtual node on an auxiliary graph; S302. Determine the connection relationship between nodes according to the crosstalk effect between each fiber core and mode group. If there is crosstalk effect, it is determined that the two virtual nodes are connected. The crosstalk effect evaluation criteria are as follows: ① If the same mode between adjacent fiber cores uses the same frequency slot, it will produce inter-core crosstalk effect, and the inter-core crosstalk effect between non-adjacent fiber cores can be ignored; ② If adjacent modes in the same fiber core use the same frequency slot, it will produce inter-mode crosstalk effect, and the inter-mode crosstalk effect between non-adjacent modes can be ignored; S303. Draw an auxiliary graph consisting of each node through the obtained connection relationship; S304. Calculate the degree of each node according to the auxiliary undirected graph obtained in S303; S305. Sort the degree of each node in ascending order, and then add each node to the priority queue H in turn, with the node with the highest priority at the head of the queue and the node with the lowest priority at the tail of the queue.

3. The resource allocation method for core-to-core crosstalk awareness in a multi-core multimode optical fiber elastic optical network according to claim 1, characterized in that: In step S7, the steps of screening available spectrum blocks are: S701. For idle spectrum block set SB free All spectrum blocks in , using the mode-interference avoidance method, for the idle spectrum block set SB free For any frequency slot in the fiber core, according to the mode in which it is located, it searches and determines whether the frequency slot with the same serial number on the adjacent mode in the same fiber core is occupied. If it is occupied, it is removed from the idle spectrum block set SB. free , and in this way the spectrum block set SB that satisfies the inter-mode crosstalk constraint is calculated. m ; S702. Spectrum block set SB that meets the inter-mode crosstalk constraint m Calculate the inter-core crosstalk value for all spectrum blocks in the The calculation formula for core-to-core crosstalk is: In the calculation formula of core-to-core crosstalk, h is the crosstalk increment per unit length. The working fiber core c selected for the service request and the adjacent fiber core c′ occupy the same frequency slot f i The resulting crosstalk value, Indicates the transmission path L of the service request r r Upper frequency gap f i The total crosstalk value of In the calculation of the crosstalk increment h per unit length, δ c,c′ is the coupling coefficient between core c and core c′, B r is the bending radius, β is the mode propagation constant and β=k×n eff , n eff The effective refractive index of the mode m selected for the service request is k = 2π / λ, where k is the wave number, λ is the wavelength of light in vacuum, and γ c,c′ is the core distance between core c and core c′; exist In the calculation of k r represents each link on the transmission path of the service request r, For Link Length; in XT fi (L r ), N c Indicates that it is adjacent to the fiber core c and occupies the frequency slot f i A collection of fiber cores; S703. According to the crosstalk value generated by the frequency slot used by the existing service request in the network to the pre-allocated frequency slot of the current incoming service request, and the crosstalk value generated by the pre-allocated frequency slot of the new incoming service request interfering with the frequency slot used by other existing service requests, the core-to-core crosstalk perception method is adopted, that is, only when the crosstalk values ​​of both are lower than the preset crosstalk threshold, the core-to-core crosstalk constraint is met, thereby screening out SB m The available spectrum blocks in the set SB usable middle.

4. The resource allocation method for core-to-core crosstalk awareness in a multi-core multimode optical fiber elastic optical network according to claim 1, characterized in that: In step S8, the calculation formula of the fragmentation coefficient FC is defined as follows: S801. Calculate the set SB usable The frequency domain fragmentation coefficient of each available spectrum block in is determined by the future allocation applicability weight w a and the future allocation unsuitability weight w b Decide; link The frequency domain fragmentation coefficient on The calculation formula is: S802. Calculate the set SB usable The time domain fragmentation coefficient of each available spectrum block in is used to find the spectrum block whose remaining time best matches the requested duration, and the remaining time ts requested on the left side of the spectrum block is left , spectrum block right side request remaining time ts right , and the duration t of the service request r r Decide; Temporal fragmentation coefficient The calculation formula is: S803. Calculate the fragmentation coefficient (FC i ), which comprehensively considers the impact of frequency domain fragmentation and time domain fragmentation; Fragmentation coefficient FC i The calculation formula is:

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