Method and system for establishing connection request for C + L wave band elastic optical network

Abstract

The invention relates to a method and a system for establishing a connection request for a C + L wave band elastic optical network. The method comprises the following steps: acquiring a connection request; finding out a candidate working path with the shortest path in the optical network; calculating the number of frequency slots required by the connection request on the shortest candidate working path; judging whether available spectrum blocks corresponding to the number of frequency slots required on a working path exist on spectrum resources of each link or not, if so, selecting the candidate spectrum blocks meeting the condition as the connection request, and if not, establishing a postpone for the connection request; judging whether the optical signal-to-noise ratio of the candidate frequency spectrum block meets the requirement or not, if so, retaining the occupation state of the candidate frequency spectrum block, otherwise, postponing the connection request; and if the connection request finds the protection path, the request establishment is successful, otherwise, the connection request is delayed, and the delayed connection request judges whether resources are distributed to the connection request again or direct establishment fails according to the type. According to the invention, effective spectrum resource allocation can be carried out on the connection request.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of elastic optical networks, and particularly to a method and system for establishing a connection request in a C+L band elastic optical network. BACKGROUND

[0002] In recent years, network connection requests are gradually evolving from traditional data transmission to computationally intensive and interactive applications. Whether it is the exchange of massive model parameters of AI training clusters or real-time connection requests such as cloud rendering and remote XR, higher throughput and transmission quality requirements are placed on the underlying optical communication network. The traditional optical network architecture with a single band and fixed bandwidth allocation has been unable to adapt to the growing demand for elastic scheduling of connection requests, and its available spectrum resources have gradually approached the upper limit in terms of scalability.

[0003] In order to improve spectrum utilization efficiency and implement on-demand scheduling of connection requests, elastic optical networks (EON) are proposed, and through variable grid technology, the spectrum is finely sliced, so that the link spectrum can be flexibly allocated according to the bandwidth requirements of connection requests. This technology effectively alleviates the problem of "coarse frequency grid and serious waste" in traditional WDM systems, providing a new direction for network capacity expansion.

[0004] However, most current EONs still rely on the C band as the main transmission window. With the accumulation of spectrum fragmentation and the continuous growth of connection request size, the allocable resources of a single C band have been difficult to support future super-large-scale interconnection scenarios. To break this limitation, the industry has gradually begun to use the L band as an extension of the C band, thereby forming a C+L multi-band joint transmission architecture, almost doubling the available spectrum range and becoming the mainstream technology path for improving network capacity.

[0005] However, the introduction of the L band also brings problems such as amplified noise accumulation, power imbalance, and cross-band performance differences, especially exacerbating inter-channel stimulated Raman scattering (ISRS) and amplified spontaneous emission noise (ASE). These damage factors will seriously degrade the transmission quality of current connection requests, so it is crucial to accurately evaluate the link transmission performance when deploying C+L bands. If the traditional idle-first or bandwidth matching-first strategy is still followed without considering the damage differences between bands, it will often lead to failure to allocate connection requests on L band frequency resources or insufficient OSNR, thereby increasing the blocking rate and inhibiting the effective use of the L band.

[0006] Meanwhile, as connection requests continuously arrive and release dynamically, the remaining spectrum of the link not only presents a fragmentation feature in the frequency dimension, but also presents a dislocation distribution of "short available, long unavailable, and superimposed across requests" in the time dimension. In order to fundamentally improve the resource utilization, it is necessary to introduce a two-dimensional resource description model of time and spectrum to realize the fine regulation and control of connection requests. And introduce immediate reservation (IR) and advance reservation (AR) requests, IR requests need to be served immediately after arrival, if the network has no enough spectrum resources available at this time, the request is blocked immediately. AR requests allow users to reserve network resources in advance for future needs.

[0007] In summary, the existing spectrum resource allocation of C+L band cannot effectively improve the network capacity, and the network has a certain blocking rate. SUMMARY

[0008] Therefore, the technical problem to be solved by the present application is to overcome the problem that the existing spectrum resource allocation of C+L band cannot effectively improve the network capacity, and the network has a certain blocking rate.

[0009] To solve the above technical problems, the present application provides a method for establishing a connection request of a C+L band elastic optical network, comprising:

[0010] Step S1: initializing the C+L band elastic optical network;

[0011] Step S2: obtaining a connection request, calculating a candidate working path set of the connection request in the C+L band elastic optical network, and selecting a shortest candidate working path from the candidate working path set, wherein the shortest candidate working path includes a plurality of nodes, and the adjacent nodes are links;

[0012] Step S3: calculating the number of frequency slots required by the connection request on the shortest candidate working path, wherein the frequency slot is a spectrum resource for establishing a connection request;

[0013] Step S4: judging whether there is an available spectrum block that meets the number of frequency slots required by the working path in the spectrum resource of each link with spectrum consistency and spectrum continuity as constraints, the available spectrum block is a plurality of continuous frequency slots at the same position of the spectrum resource of each link, if there is an available spectrum block, step S5 is executed, if there is no available spectrum block, the connection request is suspended and step S8 is executed;

[0014] Step S5: calculating impairment values of all available spectrum blocks, and selecting a spectrum block with the smallest impairment value as a candidate spectrum block of the connection request;

[0015] Step S6: calculating an optical signal-to-noise ratio of the candidate spectrum block, if the optical signal-to-noise ratio is greater than a preset signal-to-noise ratio threshold, maintaining an occupation state of the candidate spectrum block, and performing step S7; if the optical signal-to-noise ratio is less than the preset signal-to-noise ratio threshold, suspending the connection request, and performing step S8;

[0016] Step S7: calculating a protection path of the connection request, the protection path being disjoint with a working path, if the protection path is found, the connection request is successfully established; if the protection path is not found, suspending the connection request, and performing step S8;

[0017] Step S8: judging a type of the connection request, if the connection request is an AR request, returning to step S2 after delaying a preset time; if the connection request is an IR request, the connection request is failed.

[0018] In an embodiment of the present application, the connection request in step S2 is represented as CR , , , , , , , wherein, and represent a source node and a sink node of a transmission path of the connection request in a topology, represents a bandwidth size required by the connection request, represents a required time slot number, and represent start and end times of the connection request, is a maximum delay time of the connection request.

[0019] In an embodiment of the present application, the step S3 includes the following steps:

[0020] calculating the required frequency slot number of the connection request on the shortest candidate working path according to the bandwidth of the connection request and a modulation format corresponding to the shortest candidate working path , and the formula is:

[0021] (1);

[0022] wherein, is a protection spectrum slot, Bandwidth size of each frequency spectrum slot, modulation format set = {1, 2, 3, 4}, 1 represents binary phase shift keying, 2 represents quadrature phase shift keying, 3 represents eight-order quadrature amplitude modulation, and 4 represents 16-order quadrature amplitude modulation.

[0023] In an embodiment of the present application, the step S5 calculates the damage value of all available spectrum blocks by the method comprising:

[0024] When performing spectrum resource allocation on the connection request, a damage-aware matrix based on frequency slots and links is constructed, the damage-aware matrix comprising damage values of all available spectrum blocks, and being expressed as:

[0025] (2) ;

[0026] Wherein, represents a damage-aware matrix with dimension , represents a damage value of the th available spectrum block on the th link.

[0027] In an embodiment of the present application, the damage value of the th available spectrum block on the th link is calculated by the formula:

[0028] (3) ;

[0029] Wherein, represents a set of existing requests on the link , is a start time of a current request on the current link , is a departure time of other requests on the current link , is a maximum duration of other requests on the current link , represents mutual channel interference suffered by the request when the request is allocated to the frequency slot at the index , represents self-channel interference suffered by the request when the request is allocated to the frequency slot at the index ; The formula is different when allocating working path resources and protection path resources, and is specifically:

[0030] ​​​​;

[0031] ;

[0032] wherein, represents the allocation of working path resources corresponding formula, represents the allocation of protection path resources corresponding formula, represents the adjacent link set of the current link, represents the frequency slot of the corresponding spectrum region under the adjacent link, represents the time slot of the corresponding spectrum region under the adjacent link, represents the total number of frequency slots in the region, represents the number of unoccupied frequency slots in the region, represents the number of frequency slots occupied as working resources in the region.

[0033] In an embodiment of the present application, the step S6 calculates the optical signal-to-noise ratio of the candidate spectrum block, and the formula is:

[0034] (4);

[0035] wherein, is the optical signal-to-noise ratio of the candidate spectrum block, is the transmission power of the connection request ;

[0036] is the ASE noise power of the connection request and is expressed as:

[0037] (5);

[0038] wherein, denotes the spontaneous emission factor, is the Planck constant, is the number of spans of the link, denotes the length of the th span of the link , denotes the fiber attenuation coefficient, denotes the center frequency of the connection request , denotes the required bandwidth of the connection request , denotes the selected working path of the connection request ;

[0039] denotes the selected working path of the connection request The noise power caused by all nonlinear effects in the transmission process is represented as:

[0040] (6);

[0041] wherein, represents a connection request in the link transmission, refers to a request in the link transmission.

[0042] In an embodiment of the present application, and are respectively represented as:

[0043] (7);

[0044] (8);

[0045] wherein, represents the number of spans of the link , and represents the number of connection requests deployed along the link; is the nonlinear coefficient of the optical fiber, is the linear regression slope of the normalized Raman gain spectrum, represents the deployed connection requests of the link , is the center frequency of the deployed connection request, represents the number of connection requests deployed along the link;

[0046] and are respectively represented as:

[0047] (9);

[0048] (10);

[0049] wherein, and represent the linear slopes corresponding to different groups of velocity dispersion parameters.

[0050] To solve the above technical problems, the present application provides a system for establishing a connection request in a C+L band elastic optical network, comprising:

[0051] An initialization module: used for initializing the C+L band elastic optical network;

[0052] The selection module is used for obtaining a connection request, calculating a candidate working path set of the connection request in the C+L band elastic optical network, and selecting a shortest-path candidate working path from the candidate working path set, wherein the shortest-path candidate working path comprises a plurality of nodes and links between adjacent nodes.

[0053] The calculation module is used for calculating a required frequency slot number of the connection request on the shortest-path candidate working path, wherein the frequency slot is a frequency spectrum resource for establishing the connection request.

[0054] The judgment module is used for judging whether there is an available spectrum block on the frequency spectrum resource of each link in the shortest-path candidate working path under the constraints of spectrum consistency and spectrum continuity, the available spectrum block is a plurality of continuous frequency slots at the same position of the frequency spectrum resource of each link, if the available spectrum block exists, the comparison module is executed, if the available spectrum block does not exist, the connection request establishment is suspended and the third judgment module is executed.

[0055] The comparison module is used for calculating damage values of all available spectrum blocks and selecting a spectrum block with the minimum damage value as a candidate spectrum block of the connection request.

[0056] The first judgment module is used for calculating an optical signal-to-noise ratio of the candidate spectrum block, if the optical signal-to-noise ratio is greater than a preset signal-to-noise ratio threshold, the occupation state of the candidate spectrum block is reserved, and the second judgment module is executed, if the optical signal-to-noise ratio is less than the preset signal-to-noise ratio threshold, the connection request establishment is suspended, and the third judgment module is executed.

[0057] The second judgment module is used for calculating a protection path of the connection request, the protection path is non-intersecting with the working path, if the protection path is found, the connection request establishment is successful, if the protection path is not found, the connection request establishment is suspended, and the third judgment module is executed.

[0058] The third judgment module is used for judging a type of the connection request, if the connection request is an AR request, the connection request is returned to the selection module after a preset time delay, if the connection request is an IR request, the connection request establishment fails.

[0059] To solve the above technical problems, the present application provides an electronic device, which comprises a memory, a processor and a computer program stored in the memory and capable of running on the processor, and the processor implements the steps of the method for establishing a connection request in a C+L band elastic optical network when executing the computer program.

[0060] To solve the above technical problems, the application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to realize the steps of the method for C+L band elastic optical network connection request establishment.

[0061] The above technical solution of the application has the following advantages compared with the prior art:

[0062] The method for C+L band elastic optical network connection request establishment provided by the application combines network modeling, performance evaluation, resource allocation and protection mechanism organically, realizes dynamic monitoring of the whole process of service establishment, guarantees the accuracy of network modeling and the controllability of transmission performance, and through the damage perception mechanism, makes the resource allocation process more intelligent and refined, avoids the problem that only topology and availability are considered and physical damage is ignored in the traditional method. The application greatly increases the utilization rate of spectrum and reduces the fragmentation of spectrum through different allocation methods of working resources and protection resources. Therefore, the application can be applied to large-scale backbone optical networks and data center interconnection scenes, and can be popularized to future computing power networks and intelligent optical transmission systems, and has wide application prospects in improving network carrying capacity, guaranteeing transmission quality and reducing blocking rate. BRIEF DESCRIPTION OF DRAWINGS

[0063] In order to make the content of the application more easily understood, the application will be further described in detail below according to specific embodiments of the application and in combination with the drawings.

[0064] Figure 1 is a method flowchart of the application;

[0065] Figure 2 is a spectrum resource allocation schematic diagram of the application. DETAILED DESCRIPTION

[0066] The application will be further described below in combination with the drawings and specific embodiments, so that those skilled in the art can better understand the application and implement it, but the embodiments are not limiting to the application.

[0067] Embodiment one

[0068] Referring to Figure 1 The application relates to a method for C+L band elastic optical network connection request establishment, which comprises the following steps:

[0069] Step S1: initializing the C+L band elastic optical network;

[0070] Step S2: obtaining a connection request, calculating a candidate working path set of the connection request in the C+L band elastic optical network, and selecting a shortest-path candidate working path from the candidate working path set, wherein the shortest-path candidate working path comprises a plurality of nodes and links between adjacent nodes;

[0071] Step S3: calculating a required frequency slot number of the connection request on the shortest-path candidate working path, wherein a frequency slot is a spectrum resource for establishing the connection request;

[0072] Step S4: judging whether there is an available spectrum block satisfying the required frequency slot number of the working path in the spectrum resource of each link in the shortest-path candidate working path under the constraints of spectrum consistency and spectrum continuity, the available spectrum block being a plurality of continuous frequency slots at the same position of the spectrum resource of each link, and if there is the available spectrum block, performing step S5, and if there is not the available spectrum block, delaying the establishment of the connection request and performing step S8;

[0073] Step S5: calculating impairment values of all available spectrum blocks, and selecting a spectrum block with the minimum impairment value as a candidate spectrum block of the connection request;

[0074] Step S6: calculating an optical signal-to-noise ratio of the candidate spectrum block, if the optical signal-to-noise ratio is greater than a preset signal-to-noise ratio threshold, reserving an occupation state of the candidate spectrum block, and performing step S7, and if the optical signal-to-noise ratio is less than the preset signal-to-noise ratio threshold, delaying the establishment of the connection request and performing step S8;

[0075] Step S7: calculating a protection path of the connection request, the protection path being non-intersected with the working path, if the protection path is found, the connection request is successfully established, and if the protection path is not found, delaying the establishment of the connection request and performing step S8;

[0076] Step S8: judging a type of the connection request, if the connection request is an AR (advance-reservation) request, returning to step S2 after delaying the connection request for a preset time, and if the connection request is an IR (Immediate-Reservation) request, failing to establish the connection request.

[0077] The IR request is an immediate reservation request, requiring the network to allocate required resources for the request immediately when the request arrives, and if the network does not have enough available spectrum resources at this time, the request is immediately blocked. The AR request is an advance reservation request, allowing a user to reserve required resources before a service starts.

[0078] The following will be described in detail.

[0079] The method for establishing connection requests in C+L band elastic optical networks proposed in this invention comprises the following steps:

[0080] Step 1: Initialize the C+L band optical network. The network is represented by G(V, D, F). V represents the set of all connection request origins and destinations in the network, i.e., all optical switching nodes. D represents the set of paths between nodes in the optical network, i.e., the set of actual physical links between various switching nodes in the actual optical communication network. F represents the total number of frequency slots in the optical fiber laid on the actual physical link. For example, the total number of frequency slots in the C+L band can be set to 916, of which 375 belong to the C band, 10 (376-385) are the guard bandwidth between the C band and the L band, and the remaining 531 slots belong to the L band. The number of time slots is 10.

[0081] For each link, the available spectrum in the C-band and L-band is uniformly divided into frequency slots with fixed granularity (e.g., 12.5 GHz). Figure 2 Each small square in the mid-spectrum resource has a unique index number. The slot status is idle, active, or protected.

[0082] Step 2: Obtain a connection request, represented as: CR( , , , , , , ),in, and These represent the source and destination nodes, respectively, of the path the connection request takes through the topology. This indicates the bandwidth required for the current request. Indicates the required number of time slots. and This indicates the start and end times of the connection request. This is the maximum delay time for the current connection request. If the value is zero, the current connection request type is an IR request; if If the value is not zero, then the current connection request type is an AR request.

[0083] This embodiment uses a K-shortest path algorithm and considers the source node of the connection request. Heshu Node The candidate working path set of the connection request is calculated in the C+L band elastic optical network, and the shortest candidate working path is selected from the candidate working path set, wherein the shortest candidate working path includes a plurality of nodes and links between adjacent nodes, and a corresponding modulation format is selected for each link according to the length of each link.

[0084] Step 3: The embodiment calculates the number of frequency slots required for the connection request on the shortest candidate working path according to the bandwidth of the connection request , and the modulation format corresponding to the shortest candidate working path. The formula is:

[0085] (1);

[0086] wherein, is the guard frequency slot, the bandwidth of each frequency slot, is 12.5 GHz; the modulation format set ={1, 2, 3, 4}, 1 represents binary phase shift keying (BPSK), 2 represents quadrature phase shift keying (QPSK), 3 represents 8-ary quadrature amplitude modulation (8-QAM), and 4 represents 16-ary quadrature amplitude modulation (16-QAM). The embodiment considers four modulation formats, and in the selection of the modulation format, the actual physical transmission distance of the selected working path of the connection request is calculated, and the most efficient modulation format is selected to meet the transmission distance requirement.

[0087] Table 1

[0088]

[0089] Step 4: In the shortest candidate working path described above, whether there is an available spectrum block (i.e. Figure 2 available spectrum area 1 and available spectrum area 2) that meets the number of frequency slots required by the working path on the spectrum resource is judged with the constraints of spectrum consistency and spectrum continuity, the available spectrum block is a plurality of continuous frequency slots at the same position of the spectrum resource of each link, if there is an available spectrum block, step 5 is executed, if there is no available spectrum block, the connection request is suspended and step 8 is executed.

[0090] Step 5: When allocating spectrum resource for connection request, a link-slot based impairment aware matrix is constructed, which includes impairment values of all available spectrum blocks, and the spectrum block with the minimum impairment value is selected as the candidate spectrum block for the connection request. The impairment aware matrix is denoted as:

[0091] (2)

[0092] wherein, denotes the impairment aware matrix with dimension , denotes the impairment value of the mthavailable spectrum block on the nthlink, wherein is the index of the alternative spectrum slot, is the specific link in the candidate path. If there are multiple time slot areas in the same wavelength range, the area with the earlier time slot number is selected. contains two factors: unavailability impact and impairment value. The impairment value is composed of two parts: one part represents the inter-channel interference suffered by the request during transmission, and the other part represents the self-channel interference suffered by the request during transmission. The unavailability impact refers to the number of unavailable spectrum slots in the spectrum range corresponding to the current link and adjacent links when occupying the current area. When selecting working resources, the embodiment mainly considers the ratio of the number of unavailable spectrum slots to the number of all spectrum slots in the corresponding spectrum range. After modeling the impairment aware matrix, the spectrum block with the minimum impairment value is preferentially selected as the occupied area (i.e. the candidate spectrum block for the connection request).

[0093] Further, the impairment value of the mthavailable spectrum block on the nthlink is calculated according to the following formula:

[0094] (3);

[0095] wherein, denotes the set of existing requests on the link , is the start time of the current request on the current link , is the departure time of other requests on the current link , is the maximum duration of other requests on the current link , represents the inter-channel interference suffered by the request when the request is allocated to the spectrum slot at the index . ​​​​​representing the request assigned to the frequency slot at the index channel interference; The formulas are different when allocating working path resources and protection path resources, which are as follows:

[0096]

[0097]

[0098] wherein, representing the allocation of working path resources The corresponding formula is, representing the allocation of protection path resources The corresponding formula is, representing the adjacent link set of the current link, representing the frequency slot of the corresponding spectrum region under the adjacent link, representing the time slot of the corresponding spectrum region under the adjacent link, representing the total number of frequency slots in the region, representing the number of unoccupied frequency slots in the region, representing the number of frequency slots occupied as working resources in the region.

[0099] Step 6: Calculate the optical signal-to-noise ratio of the candidate spectrum block. If the optical signal-to-noise ratio is greater than the preset signal-to-noise ratio threshold (OSNR threshold in Table 1), the occupation state of the candidate spectrum block is retained, and step 7 is performed. If the optical signal-to-noise ratio is less than the preset signal-to-noise ratio threshold (OSNR threshold in Table 1), the connection request is suspended, and step 8 is performed. Specifically, in the C+L band flexible optical network, the calculation of the optical signal-to-noise ratio not only needs to consider the traditional ASE (Amplified Spontaneous Emission) noise, but also needs to consider the inter-channel stimulated Raman scattering ISRS (Inter-Channel Stimulated Raman Scattering). ASE noise is the spontaneous emission photon noise generated by the optical amplifier in the process of amplifying optical signals. In a long-distance transmission system, ASE noise will accumulate gradually after the optical signal passes through multiple optical amplifiers in cascade. The cause of ISRS is that when light is transmitted in an optical fiber, photons interact with molecules in the optical fiber, causing molecular vibration. The Kerr electro-optic effect causes various phenomena in optical communication, such as self-phase modulation (SPM), cross-phase modulation (XPM), and four-wave mixing (FWM). Therefore, in a multi-band network, the noise caused by nonlinear effects is equally important as ASE noise, and both are important parts that cannot be ignored when calculating the signal-to-noise ratio. In this embodiment, the optical signal-to-noise ratio calculation formula of the candidate spectrum block is:

[0100] (4)

[0101] wherein, is the optical signal-to-noise ratio of the candidate spectrum block, is the transmission power of the connection request , is the ASE noise power of the request , represents the noise power caused by all nonlinear effects in the transmission process of the request , which is mainly divided into self-channel interference noise power and cross-channel interference noise power. For the request , the noise power is represented by the following formula:

[0102] (5)

[0103] wherein, represents the spontaneous emission factor, is the Planck constant, is the number of spans of the link, is the length of the i-th span of the link , represents the fiber attenuation coefficient, represents the center frequency of the request , represents the required bandwidth of the request , represents the selected working path of the request . The noise power caused by the nonlinear effects of the service request is represented by the following formula:

[0104] (6)

[0105] wherein, represents the self-channel interference noise power of the request in the transmission of the link , represents the cross-channel interference noise power of the request in the transmission of the link . The specific calculation of the two is given by formula (7) and formula (8):

[0106] (7)

[0107] (8)

[0108] In formula (7) and formula (8), represents the number of spans of the link , and represents the number of connection requests deployed along the link, ​a nonlinear coefficient of the optical fiber, is a linear regression slope of the normalized Raman gain spectrum, represents a link a deployed connection request, is a center frequency of the deployed connection request, denotes a number of connection requests deployed along the link, and are expressed by formula (9) and formula (10):

[0109] (9)

[0110] (10)

[0111] wherein, and denote linear slopes corresponding to different sets of velocity dispersion parameters, and by the above formulas, the OSNR can be accurately calculated to evaluate the transmission quality in a high-capacity optical network involving multi-wavelength long-distance transmission.

[0112] It should be noted that when calculating the optical signal-to-noise ratio of the candidate spectrum block, if the optical signal-to-noise ratio is less than the preset signal-to-noise ratio threshold (OSNR threshold in Table 1), the strategy corresponding to the above method is: the connection request is suspended, and step 8 is performed. In other embodiments, if the optical signal-to-noise ratio is less than the preset signal-to-noise ratio threshold, the modulation level in Table 1 can also be reduced by one level, for example, 8-QAM (corresponding to modulation level 3) is reduced to QPSK (corresponding to modulation level 2), and then the optical signal-to-noise ratio is recalculated and it is judged whether it is greater than the preset signal-to-noise ratio threshold. If the threshold condition is met at this time, the occupation state of the candidate spectrum block is retained, and step 7 is performed. If the threshold condition is not met at this time, the modulation level is reduced by one level (BPSK corresponds to modulation level 1) for judgment. If the threshold condition is met, the occupation state of the candidate spectrum block is retained, and step 7 is performed. If the threshold condition is not met, the connection request is suspended, and step 8 is performed.

[0113] Step 7: Calculate the protection path of the connection request (the protection path is used to transmit the connection request when the working path fails), the protection path is disjointed with the working path, if the protection path is found, the connection request is successfully established; if the protection path is not found, the connection request is suspended, and step 8 is performed. It should be noted that the selection method of the protection path is the same as that of the working path, which will not be described here.

[0114] Step 8: Determine the type of the connection request, if the connection request is an AR request, the connection request returns to step 2 after a preset time (equivalent to allocating spectrum resources for the connection request again); if the connection request is an IR request, the connection request fails.

[0115] Please refer to Figure 2 When a connection request CR (3, 7, 60, 2, 64, 128, 30) arrives, a candidate working path set can be obtained by calculation, and at this time, the shortest candidate working path in the candidate working path set is selected as: node 3-node 4-node 6-node 7, from Figure 2 It can be found from the above that the distance of the shortest candidate working path is 600+700+700=2000, and thus the corresponding modulation format is 8-QAM. According to the principles of spectral consistency and spectral continuity, all available spectrum regions (i.e. available spectrum blocks) are found in the link 3-4, the link 4-6, and the link 6-7, and in Figure 2 The available spectrum regions are 2 (available spectrum region 1 and available spectrum region 2), and the number of links is 3, thus forming a two-dimensional damage perception matrix of 2x3. Finally, through the scoring principle, the score of the available spectrum region 1 is 82.51, and the score of the available spectrum region 2 is 89.78. It can be seen that the value of the available spectrum region 1 is the lowest, and thus the priority is the highest. The available spectrum region 1 is selected as the pre-occupied area of the working resource, and then the optical signal-to-noise ratio when transmitting in this area is calculated according to the OSNR calculation formula (formula (4)), and the calculated value is 20.45, which is greater than the threshold 16 under the current modulation format (8-QAM). Finally, the protection path for the connection request is calculated as: node 3-node 8-node 11-node 9-node 7, and the protection resource allocation is performed.

[0116] Embodiment two

[0117] The embodiment provides a system for establishing a connection request of a C+L band elastic optical network, comprising:

[0118] An initialization module is configured to initialize the C+L band elastic optical network;

[0119] A selection module is configured to obtain a connection request, calculate a candidate working path set of the connection request in the C+L band elastic optical network, and select a candidate working path with the shortest path from the candidate working path set, wherein the candidate working path with the shortest path comprises a plurality of nodes, and links between adjacent nodes.

[0120] A calculation module is configured to calculate the number of frequency slots required by the connection request on the shortest candidate working path, wherein a frequency slot is a spectrum resource for establishing a connection request.

[0121] A judging module is configured to judge whether there is an available spectrum block in the spectrum resource of each link in the candidate working path with the shortest path, the available spectrum block being a plurality of continuous frequency slots at the same position of the spectrum resource of each link, the frequency slots satisfying the required number of frequency slots in the working path, and the spectrum consistency and spectrum continuity being constraints, if the available spectrum block exists, the comparing module is executed, and if the available spectrum block does not exist, the connection request is suspended and the third judging module is executed.

[0122] The comparing module is configured to calculate impairment values of all available spectrum blocks, and select a spectrum block with the minimum impairment value as a candidate spectrum block of the connection request.

[0123] The first judging module is configured to calculate an optical signal-to-noise ratio of the candidate spectrum block, if the optical signal-to-noise ratio is greater than a preset signal-to-noise ratio threshold, the occupation state of the candidate spectrum block is reserved, and the second judging module is executed, and if the optical signal-to-noise ratio is less than the preset signal-to-noise ratio threshold, the connection request is suspended, and the third judging module is executed.

[0124] The second judging module is configured to calculate a protection path of the connection request, the protection path being non-intersected with the working path, if the protection path is found, the connection request is successfully established, and if the protection path is not found, the connection request is suspended, and the third judging module is executed.

[0125] The third judging module is configured to judge the type of the connection request, if the connection request is an AR request, the connection request is returned to the selecting module after a preset time is delayed, and if the connection request is an IR request, the connection request fails.

[0126] Embodiment three

[0127] The embodiment provides an electronic device, which comprises a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the method for establishing a connection request of a C+L waveband elastic optical network according to the embodiment one when executing the computer program.

[0128] Embodiment four

[0129] The embodiment provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the steps of the method for establishing a connection request of a C+L waveband elastic optical network according to the embodiment one.

[0130] Those skilled in the art will appreciate that embodiments of the present application can be readily used as software, hardware, or a combination of software and hardware. In one embodiment, the present application can be implemented in software and can be stored on a computer readable medium, which can include random access memory (RAM), read only memory (ROM), magnetic disk or optical disk, or the like. The software implementation can comprise one or more computer program components embodied on one or more computer readable medium(s). The computer readable medium can be resident within the computing device or external to the computing device. The computer program components can also be downloaded into the computing device from an external computer or external storage device.

[0131] The present application is described in reference to the flowchart illustrations and / or block diagrams according to embodiments of the application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processing device or other programmable data processing device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing device, create means for implementing the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0132] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0133] These computer program instructions can also be loaded onto a computer or other programmable data processing device to cause a series of operational steps to be performed on the computer or other programmable device to produce a computer implemented process such that the instructions which execute on the computer or other programmable device provide steps for implementing the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0134] While preferred embodiments of the application have been described, modifications and variations can be apparent to those skilled in the art once aware of the general underlying concepts. Accordingly, the appended claims are intended to encompass all modifications and variations of the preferred embodiments which fall within the scope of the application.

[0135] Obviously, the above-mentioned embodiments are only examples for clearly illustrating the present application, and are not intended to limit the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary and also impossible to enumerate all the embodiments. The obvious changes or variations derived from the above description are still within the protection scope of the present application.

Claims

1. A method for establishing a connection request in a C+L band elastic optical network, characterized in that: include: Step S1: Initialize the C+L band elastic optical network; Step S2: Obtain a connection request, calculate the candidate working path set of the connection request in the C+L band elastic optical network, and select the candidate working path with the shortest path from the candidate working path set. The candidate working path with the shortest path includes several nodes, and the adjacent nodes are links. Step S3: Calculate the number of frequency slots required by the connection request on the shortest candidate working path, where a frequency slot is the spectrum resource for establishing the connection request; Step S4: In the candidate working path with the shortest path, with spectrum consistency and spectrum continuity as constraints, determine whether there are available spectrum blocks on each link that meet the number of frequency slots required on the working path. The available spectrum blocks are several consecutive frequency slots at the same position on the spectrum resources of each link. If there are available spectrum blocks, proceed to step S5. If there are no available spectrum blocks, postpone the connection request and proceed to step S8. Step S5: Calculate the impairment value of all available spectrum blocks and select the spectrum block with the smallest impairment value as the candidate spectrum block for the connection request; Step S6: Calculate the optical signal-to-noise ratio (SNR) of the candidate spectrum block. If the SNR is greater than a preset SNR threshold, retain the occupancy status of the candidate spectrum block and proceed to step S7. If the SNR is less than the preset SNR threshold, postpone the connection request establishment and proceed to step S8. Step S7: Calculate the protection path of the connection request. The protection path does not intersect with the working path. If a protection path is found, the connection request is successfully established; if no protection path is found, the connection request is postponed, and step S8 is executed. Step S8: Determine the type of the connection request. If the connection request is an AR request, the connection request will be delayed for a preset time and then returned to step S2. If the connection request is an IR request, the connection request will fail to be established.

2. The method for establishing a connection request in a C+L band elastic optical network according to claim 1, characterized in that: The connection request in step S2 is represented as CR( , , , , , , ),in, and These represent the source and destination nodes, respectively, of the path the connection request takes through the topology. This indicates the bandwidth required for the connection request. Indicates the required number of time slots. and Indicates the start and end times of the connection request. This is the maximum latency for connection requests.

3. The method for establishing a connection request in a C+L band elastic optical network according to claim 1, characterized in that: The method for calculating the number of bandwidths required by the connection request on the shortest candidate working path in step S3 includes: Based on the bandwidth of the connection request The number of frequency slots required by the connection request on the shortest candidate working path is calculated using the modulation format corresponding to the shortest candidate working path. The formula is: (1)； in, To protect the spectral gap, The bandwidth of each spectral slot, the set of modulation formats ={1, 2, 3, 4}, where 1 represents binary phase shift keying, 2 represents quadrature phase shift keying, 3 represents 8th-order quadrature amplitude modulation, and 4 represents 16th-order quadrature amplitude modulation.

4. The method for establishing a connection request in a C+L band elastic optical network according to claim 3, characterized in that: The method for calculating the impairment value of all available spectral blocks in step S5 includes: When allocating spectrum resources for connection requests, a damage perception matrix based on frequency slots and links is constructed. This damage perception matrix includes the damage values ​​of all available spectrum blocks, expressed as: (2)； in, Dimension The damage perception matrix, Indicates the first The first link Damage value of each available spectral block.

5. The method for establishing a connection request in a C+L band elastic optical network according to claim 4, characterized in that: The first The first link Damage value of each available spectrum block The calculation formula is: (3)； in, Indicates link The existing set of requests, The current link Current request The start time, The current link Other requests The time of departure, The current link Other requests The maximum duration, The representative will request Assigned to index When the frequency slot is at a certain location, the request is subject to cross-channel interference. The representative will request Assigned to index When the frequency slot is at a certain location, the request is subject to channel interference. The formulas for allocating working path resources and protection path resources are different, specifically: ； ； in, This represents the allocation of work path resources. The corresponding formula, This represents the allocation of protected path resources. The corresponding formula, It represents the set of adjacent links of the current link. This represents the frequency slots of the corresponding spectral regions under adjacent links. This represents the time slots of the corresponding spectrum regions under adjacent links. This represents the total number of frequency slots in the region. This represents the number of unoccupied frequency slots in the region. This represents the number of slots in the area that are used as working resources.

6. The method for establishing a connection request in a C+L band elastic optical network according to claim 1, characterized in that: Step S6 calculates the optical signal-to-noise ratio of the candidate spectral block using the following formula: (4)； in, The optical signal-to-noise ratio of the candidate spectral block. For connection request The transmission power; It is a connection request. The ASE noise power is expressed as: (5)； in, Indicates the spontaneous emission factor. It is Planck's constant. It is the span of the link. Indicates link The The length of a span Indicates the fiber attenuation coefficient. Indicates a connection request The center frequency, Indicates a connection request The required bandwidth, Indicates a connection request The selected working path; Indicates a connection request The noise power caused by all nonlinear effects during transmission is expressed as: (6)； in, Indicates a connection request In the link Self-channel interference noise power during transmission, Refers to a request In the link Cross-channel interference noise power during transmission.

7. The method for establishing a connection request in a C+L band elastic optical network according to claim 6, characterized in that: and They are represented as follows: (7)； (8)； in, Indicates link The span number represents the number of connection requests deployed along the link; For the nonlinear coefficient of the optical fiber, It is the slope of the linear regression of the normalized Raman gain spectrum. This represents a link. Deployed connection requests, It is the center frequency of deployed connection requests. This represents the number of connection requests deployed along the link; and They are represented as follows: (9)； (10)； in, and This represents the linear slope corresponding to different sets of velocity dispersion parameters.

8. A system for establishing connection requests in a C+L band flexible optical network, characterized in that: include: Initialization module: Used to initialize the C+L band elastic optical network; Selection module: used to obtain a connection request, calculate a set of candidate working paths for the connection request in the C+L band elastic optical network, and select the candidate working path with the shortest path from the set of candidate working paths, wherein the candidate working path with the shortest path includes several nodes and the links between adjacent nodes; Calculation module: used to calculate the number of frequency slots required by the connection request on the shortest candidate working path, where a frequency slot is the spectrum resource for establishing the connection request; Judgment module: Used to determine, in the candidate working path with the shortest path, whether there is an available spectrum block in the spectrum resources of each link that meets the number of frequency slots required for the working path, with spectrum consistency and spectrum continuity as constraints. The available spectrum block is a number of consecutive frequency slots at the same position in the spectrum resources of each link. If there is an available spectrum block, the comparison module is executed. If there is no available spectrum block, the connection request establishment is postponed and the third judgment module is executed. Comparison module: used to calculate the impairment value of all available spectrum blocks and select the spectrum block with the smallest impairment value as the candidate spectrum block for the connection request; The first judgment module is used to calculate the optical signal-to-noise ratio (SNR) of the candidate spectrum block. If the SNR is greater than a preset SNR threshold, the occupancy status of the candidate spectrum block is retained, and the second judgment module is executed. If the SNR is less than the preset SNR threshold, the connection request establishment is postponed, and the third judgment module is executed. The second judgment module is used to calculate the protection path of the connection request. The protection path does not intersect with the working path. If a protection path is found, the connection request is successfully established; if no protection path is found, the connection request is postponed and the third judgment module is executed. The third judgment module is used to determine the type of the connection request. If the connection request is an AR request, the connection request will be returned to the selection module after a preset delay. If the connection request is an IR request, the connection request will fail to be established.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, it implements the steps of the method for establishing a connection request for a C+L band elastic optical network as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, it implements the steps of the method for establishing a connection request for a C+L band elastic optical network as described in any one of claims 1 to 7.

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