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WO2022198735A1 - 光通道性能保证下的osnr感知频谱分配方法及系统 - Google Patents

光通道性能保证下的osnr感知频谱分配方法及系统 Download PDF

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Publication number
WO2022198735A1
WO2022198735A1 PCT/CN2021/088324 CN2021088324W WO2022198735A1 WO 2022198735 A1 WO2022198735 A1 WO 2022198735A1 CN 2021088324 W CN2021088324 W CN 2021088324W WO 2022198735 A1 WO2022198735 A1 WO 2022198735A1
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Prior art keywords
osnr
optical path
optical
modulation format
service
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PCT/CN2021/088324
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English (en)
French (fr)
Inventor
沈纲祥
郭宁宁
李泳成
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苏州大学
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Priority to US17/771,462 priority Critical patent/US11818519B2/en
Publication of WO2022198735A1 publication Critical patent/WO2022198735A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0201—Add-and-drop multiplexing
    • H04J14/0202—Arrangements therefor
    • H04J14/021—Reconfigurable arrangements, e.g. reconfigurable optical add/drop multiplexers [ROADM] or tunable optical add/drop multiplexers [TOADM]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
    • H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
    • H04B10/0795—Performance monitoring; Measurement of transmission parameters
    • H04B10/07953—Monitoring or measuring OSNR, BER or Q
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q2011/0073—Provisions for forwarding or routing, e.g. lookup tables
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q2011/0084—Quality of service aspects
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q2011/0086—Network resource allocation, dimensioning or optimisation

Definitions

  • the present invention relates to the technical field of optical communication, in particular to an OSNR sensing spectrum allocation method and system under the guarantee of optical channel performance.
  • optical fibers provide optical path services for the network, so when considering a complete network topology, the results obtained by point-to-point systems cannot accurately reflect the benefits of low-loss and large-effective-area fibers for optical signal transmission in the network.
  • Traditional optical signal-to-noise ratio evaluation models are no longer accurate.
  • the technical problem to be solved by the present invention is that when overcoming the complete network topology in the prior art, the results obtained by the point-to-point system cannot accurately reflect the benefits brought by the low-loss and large-effective-area optical fibers to the optical signal transmission in the network, The technical defect that the traditional optical signal-to-noise ratio evaluation model is no longer accurate.
  • the present invention provides an OSNR sensing spectrum allocation method under the guarantee of optical channel performance, comprising the following steps:
  • OSNR evaluation model for evaluating the transmission quality of the optical path signal
  • the OSNR evaluation model includes the filtering narrowing effect caused by amplifying spontaneous emission noise, nonlinear interference and ROADM cascades
  • the first-time adaptation algorithm is used to allocate the spectrum resources required by the current service for the shortest path, and the center frequency of the current service on the optical path is obtained, and then the method further includes:
  • the full spectrum loading strategy, the margin reservation strategy and the spectrum dependence strategy are used to evaluate the OSNR quality respectively to ensure the best optical channel performance after spectrum allocation.
  • OSNR quality is evaluated using a full spectrum loading strategy, including:
  • the optical path is established and the allocation process is terminated; otherwise, the next modulation format of the current modulation format in the modulation format list is used to calculate the bandwidth required by the optical path service based on the bandwidth requirement and FEC overhead, and repeat S5 and subsequent steps until the optical path service requirements are established;
  • OSNR quality is evaluated using a margin reservation strategy, including:
  • the OSNR quality is evaluated using a spectrum-dependent strategy, including:
  • the optical path is established and the allocation process is terminated; otherwise, the next modulation format of the current modulation format in the modulation format list is used to calculate the bandwidth required by the optical path service based on the bandwidth requirement and FEC overhead, and repeat S5 and subsequent steps until the optical path service requirements are established;
  • the S1 includes:
  • the 3dB bandwidth of the filter is:
  • T is the insertion loss of the filter (in dB)
  • N f is the number of cascaded filters
  • n is the order of the Gaussian function
  • the overall signal-to-noise ratio OSNR lightpath of the optical path is:
  • P in is the transmit power of the optical path
  • P ASE is the power value of ASE noise
  • P NLI is the power value of NLI interference
  • F is the noise figure of the optical amplifier
  • h Planck's constant
  • G is the gain of the optical amplifier
  • f i is the center frequency of the signal
  • B i is the bandwidth of the signal
  • P NLI For nonlinear interference, under the assumption of additive Gaussian, P NLI can be calculated as:
  • ⁇ 2 ⁇ n 2 /( ⁇ A eff )
  • “asinh” is the hyperbolic arcsine function
  • ⁇ is the fiber attenuation coefficient
  • ⁇ 2 is the second-order fiber dispersion coefficient
  • L span is the span length
  • the span refers to the Physical link between two adjacent optical amplifiers
  • ⁇ is the wavelength of the signal
  • n2 is the nonlinear refractive index of the fiber
  • Aeff is the effective area of the fiber.
  • the multiple modulation formats in S3 include: PM-64QAM, PM-32QAM, PM-16QAM, PM-8QAM, PM-QPSK and PM-BPSK.
  • the invention discloses an OSNR sensing spectrum allocation system with guaranteed optical channel performance, comprising:
  • An OSNR building module is used to build an OSNR evaluation model for evaluating the transmission quality of an optical path signal, the OSNR evaluation model including amplifying spontaneous emission noise, nonlinear interference, and filter narrowing effects caused by ROADM cascades;
  • the shortest path acquisition module is used to send optical path service requirements, and acquire the shortest path between the source node and the target node;
  • a modulation format sorting module is configured to obtain a plurality of modulation formats and their corresponding thresholds, sort the plurality of modulation formats from high to low according to the spectral efficiency, and obtain a sorted list of modulation formats;
  • the spectrum allocation module which uses the modulation format with the highest spectral efficiency, calculates the bandwidth required by the optical path service based on bandwidth requirements and FEC overhead, and substitutes the bandwidth required by the optical path service into the OSNR evaluation model to obtain the actual service requirements. For the required number of FS, use the first adaptation algorithm to allocate the spectrum resources required by the current service for the shortest path, and obtain the center frequency of the current service on the optical path.
  • it also includes:
  • the OSNR quality assessment module uses the full spectrum loading strategy, the margin reservation strategy and the spectrum dependency strategy to assess the OSNR quality respectively, so as to ensure the best optical channel performance after spectrum allocation.
  • the present invention proposes a complete optical path signal-to-noise ratio (OSNR) estimation model considering the cascade effect of the reconfigurable optical add-drop multiplexer (ROADM).
  • OSNR optical path signal-to-noise ratio
  • the present invention proposes three spectrum allocation schemes in consideration of the cross-channel interference (XCI) between the previously established optical paths and the currently to-be-established optical paths. Simulation results show that the proposed spectrum-dependent strategy is the most effective, and the spectrum allocation of this strategy takes the current XCI value into account for each optical path.
  • XCI cross-channel interference
  • Figure 1 shows the OSNR sensing spectrum allocation method under the guarantee of optical channel performance
  • Fig. 2 is an example diagram of spectrum resources of an optical path
  • Figure 3 is a test network diagram
  • Figure 4 is a performance comparison diagram of the OSNR performance guarantee strategy
  • Figure 5 is a performance comparison diagram of different fiber types, wherein, (a) NSFNET; (b) USNET.
  • the present invention discloses an OSNR sensing spectrum allocation method with guaranteed optical channel performance, comprising the following steps:
  • Step 1 Build an OSNR evaluation model for evaluating the transmission quality of the optical path signal.
  • the OSNR evaluation model includes amplifying spontaneous emission noise, nonlinear interference, and filtering narrowing effects caused by ROADM cascades, specifically including:
  • the 3dB bandwidth of the filter is:
  • T is the insertion loss of the filter (in dB)
  • N f is the number of cascaded filters
  • n is the order of the Gaussian function
  • the overall signal-to-noise ratio OSNR lightpath of the optical path is:
  • P in is the transmit power of the optical path
  • P ASE is the power value of ASE noise
  • P NLI is the power value of NLI interference
  • F is the noise figure of the optical amplifier
  • h Planck's constant
  • G is the gain of the optical amplifier
  • f i is the center frequency of the signal
  • B i is the bandwidth of the signal
  • P NLI For nonlinear interference, under the assumption of additive Gaussian, P NLI can be calculated as:
  • ⁇ 2 ⁇ n 2 /( ⁇ A eff )
  • “asinh” is the hyperbolic arcsine function
  • ⁇ is the fiber attenuation coefficient
  • ⁇ 2 is the second-order fiber dispersion coefficient
  • L span is the span length
  • the span refers to the Physical link between two adjacent optical amplifiers
  • ⁇ is the wavelength of the signal
  • n2 is the nonlinear refractive index of the fiber
  • Aeff is the effective area of the fiber.
  • Step 2 Send the optical path service requirements to obtain the shortest path between the source node and the target node.
  • Step 3 Obtain a plurality of modulation formats and their corresponding thresholds, sort the plurality of modulation formats from high to low according to the spectral efficiency, and obtain a sorted list of modulation formats.
  • the multiple modulation formats in step 3 include: PM-64QAM, PM-32QAM, PM-16QAM, PM-8QAM, PM-QPSK and PM-BPSK.
  • Step 4 Calculate the bandwidth required by the optical path service based on the bandwidth requirement and the FEC overhead by using the modulation format with the highest spectral efficiency.
  • Step 5 Substitute the bandwidth required by the optical path service into the OSNR evaluation model to obtain the FS number actually required by the service.
  • Step 6 Use the first adaptation algorithm to allocate spectrum resources required by the current service to the shortest path, and obtain the center frequency of the current service on the optical path.
  • Step 7 Use the full spectrum loading strategy, the margin reservation strategy and the spectrum dependence strategy to evaluate the OSNR quality respectively, so as to ensure the best optical channel performance after spectrum allocation.
  • the optical path is established and the allocation process is terminated; otherwise, the next modulation format of the current modulation format in the modulation format list is used to calculate the bandwidth required by the optical path service based on the bandwidth requirement and FEC overhead, and repeat S5 and subsequent steps until the optical path service requirements are established;
  • the optical path is established and the allocation process is terminated; otherwise, the next modulation format of the current modulation format in the modulation format list is used to calculate the bandwidth required by the optical path service based on the bandwidth requirement and FEC overhead, and repeat S5 and subsequent steps until the optical path service requirements are established;
  • the invention also discloses an OSNR sensing spectrum allocation system with guaranteed optical channel performance, comprising an OSNR building module, a shortest path acquisition module, a modulation format sorting module, a spectrum allocation module and an OSNR quality evaluation module.
  • the OSNR building module is used to construct an OSNR evaluation model for evaluating the transmission quality of the optical path signal, and the OSNR evaluation model includes amplifying spontaneous emission noise, nonlinear interference and filter narrowing effects caused by ROADM cascades.
  • the shortest path acquisition module is used for sending optical path service requirements and acquiring the shortest path between the source node and the target node.
  • the modulation format sorting module is configured to acquire multiple modulation formats and their corresponding thresholds, sort the multiple modulation formats from high to low according to spectral efficiency, and obtain a sorted list of modulation formats.
  • the spectrum allocation module uses the modulation format with the highest spectral efficiency, calculates the bandwidth required by the optical path service based on bandwidth requirements and FEC overhead, and substitutes the bandwidth required for the optical path service into the OSNR evaluation model to obtain the FS actually required by the service. number, use the first adaptation algorithm to allocate spectrum resources required by the current service to the shortest path, and obtain the center frequency of the current service on the optical path.
  • the OSNR quality assessment module uses the full spectrum loading strategy, the margin reservation strategy and the spectrum dependency strategy to assess the OSNR quality respectively, so as to ensure the best optical channel performance after spectrum allocation.
  • the invention utilizes OSNR to evaluate the transmission quality of the optical path signal, including three aspects: amplified spontaneous emission noise (ASE), nonlinear interference (NLI) and filtering narrowing effect caused by ROADM cascade.
  • ASE amplified spontaneous emission noise
  • NLI nonlinear interference
  • filtering narrowing effect caused by ROADM cascade When the signal in the optical path passes through one ROADM, it means that the signal will pass through two bandpass filters, and the cascaded ROADM filters will reduce the filtering bandwidth.
  • the present invention will outline the passband shape of the cascaded filter. As shown in Figure 2, if the signal bandwidth is BW s , the 3dB bandwidth of the filter is:
  • the present invention requires an optical amplifier such as an erbium-doped fiber amplifier (EDFA) to enhance the optical signal, which introduces ASE noise (as shown in Figure 2). Then, the overall signal-to-noise ratio OSNR lightpath of the lightpath can be calculated as:
  • Pin is the transmit power of the optical path
  • P ASE is the power value of ASE noise
  • P NLI is the power value of NLI interference.
  • F is the noise figure of the optical amplifier
  • h Planck's constant
  • G is the gain of the optical amplifier
  • f i is the center frequency of the signal
  • B i is the bandwidth of the signal.
  • P NLI For nonlinear interference, under the assumption of additive Gaussian, P NLI can be calculated as:
  • ⁇ is the fiber attenuation coefficient (unit is km -1 )
  • ⁇ 2 is the second-order fiber dispersion coefficient
  • L span is the span length
  • the span refers to the two The physical link between two adjacent optical amplifiers
  • ⁇ is the wavelength of the signal
  • n 2 is the nonlinear refractive index of the fiber
  • a eff is the effective area of the fiber.
  • the ASE noise is mainly related to the attenuation coefficient of the fiber
  • the NLI interference is mainly related to the effective area of the fiber.
  • the present invention In order to calculate the signal-to-noise ratio of the optical path, the present invention first needs to know the center wavelength and bandwidth of the optical path. Therefore, the calculation of ONSR is related to the spectral allocation of each optical path. Different spectrum allocation algorithms will result in different OSNR values. For this reason, the present invention introduces routing and spectrum allocation processes next.
  • the signal-to-noise ratio estimation model proposed in the present invention takes into account all impairment effects: ASE noise, NLI interference and bandwidth narrowing caused by cascaded ROADM filters.
  • the latter two impairments are related to the spectral information on the link, and therefore need to integrate the SNR estimation with the spectrum allocation process.
  • traditional algorithms consider ASE noise to be the dominant effect of impairment independent of the spectrum allocated to the optical path, which is flawed.
  • the routing and spectrum allocation algorithm of the present invention is as follows:
  • Step 1 Enter a network topology, a list of optical path service requirements and a set of modulation formats.
  • Step 2 For each requirement, run the shortest path algorithm to find its route between the source and destination nodes of the requirement. .
  • Step 3 Try the highest modulation format first, the modulation formats are PM-64QAM, PM-32QAM, PM-16QAM, PM-8QAM, PM-QPSK and PM-BPSK.
  • Table 1 shows the spectral efficiency and forward error correction coding (FEC) limits of different modulation formats. Note that the FEC limit here is the OSNR threshold corresponding to the modulation format.
  • Step 4 Considering the influence of the cascaded ROADM filter to narrow the signal bandwidth, use formula (1) to calculate the bandwidth required by the current optical path filter, and then calculate the actual number of FS required by the service as
  • Step 5 Use the first hit strategy to allocate the spectrum resources required by the current service for the shortest path, which will determine the center frequency of the current service on the optical path.
  • Step 6 Evaluate the transmission quality OSNR of the optical path. If the OSNR meets the threshold for the current modulation format, the optical path is established and the assignment process is terminated, otherwise, go to step 3 and consider the next modulation format in the list.
  • the present invention considers incremental business scenarios, and only one business requirement is reached each time.
  • a new optical path is set up. If a previously successfully established optical path and the new optical path pass through the same link and node, the spectrum allocated on the new optical path will negatively affect its signal quality. This is mainly due to the existence of cross-channel interference (XCI) between the optical paths.
  • XCI cross-channel interference
  • MCI multi-channel interference
  • the present invention proposes the following three strategies:
  • Full spectrum loading strategy Assuming that the transmission quality of all links is the worst case, that is, the entire C-band of optical signal transmission is occupied, that is, full spectrum loading, considering all the existing XCI effects in advance, which can ensure new After the optical path is established, no additional XCI interference will be generated.
  • Margin reservation strategy Starting from the first optical path service requirement, first calculate the signal-to-noise ratio of the established optical path as OSNR current according to the current spectrum information on the optical fiber link. Considering the potential XCI effect of subsequent optical path requests, an OSNR margin value is reserved when selecting the modulation format for the current optical path, that is, OSNR current -M ⁇ FEC limit is required, where M is the set margin value, FEC limit is the OSNR threshold required by the modulation format. The margin value is determined through testing, which can ensure that all subsequent optical path requests can be successfully established.
  • Spectrum-dependent strategy This strategy is more advanced than the previous two strategies, but at the cost of higher computational complexity.
  • the present invention In order to successfully establish a new optical path LP new , first allocate spectrum resources for LP new , and then the present invention will check the optical path list ⁇ LP pre ⁇ that has been successfully established before, and observe whether the optical paths in the list that share the link with LP new can still satisfy their respective requirements. the OSNR threshold. If any one of the optical paths fails, the present invention starts from the failed optical path and releases the spectral resources used by all the unchecked optical paths. Then, for failed traffic demands, the present invention downgrades the modulation format used and reallocates the spectrum along the same route.
  • the present invention For the unchecked optical paths, the present invention reassigns the spectrum to them using the modulation format used before, and checks whether they can meet the signal-to-noise ratio requirements. The present invention repeats this process until new optical paths are successfully established, and all optical paths can meet their signal-to-noise ratio requirements.
  • the present invention contemplates three different types of optical fibers as shown in Table 2, namely G.652, G.654.E-A110 and G.654.E-A130.
  • the present invention will adopt the NSFNET with 14 nodes and 21 links.
  • the network and the USNET network with 24 nodes and 43 links are used as the test network of the present invention.
  • the specific test network is shown in Figure 3, and the link distance is in km.
  • the present invention here assumes that there is a service flow demand between each node pair, and each time a demand is provided incrementally.
  • the bandwidth requirements of each service are evenly distributed in the range of [120, X] Gb/s, where X is the maximum bandwidth requirement, and X is set to 700 and 300 in NSFNET and USNET networks, respectively. Assuming that the bandwidth of each FS is 12.5GHz, the overhead of FEC is 25%.
  • the margin values of the NSFNET and USNET networks are set to 1.5dB and 2dB, respectively. Because the USNET network is larger and more complex than the NSFNET network, the margin values are set to be larger.
  • the noise figure of the EDFA will be set to 5.5dB, and the transmit power of each optical path will be 0dBm.
  • the present invention first compares the performance of three OSNR performance guarantee strategies.
  • the fiber parameters are set as follows: the attenuation coefficient is 0.185dB/km, and the effective area is 83 ⁇ m 2 . Because the full spectrum loading strategy considers the worst case of all fiber links, the signal-to-noise ratio of each optical path is underestimated, so the modulation format level allocated is lower and more spectrum resources are required. In contrast, since the spectrum dependence strategy only considers the interference from the current optical path spectrum, the actual interference received will be lower than the result of the full spectrum loading strategy, which can calculate a higher signal-to-noise ratio and thus achieve a more efficient spectrum.
  • the number of FSs used is also the least, which is 40.8% and 38.9% lower than the results under the full spectrum loading strategy of NSFNET and USNET, respectively.
  • the margin reservation strategy also only considers the interference from the current optical path spectrum, this strategy uses the same SNR penalty for each optical path. Therefore, this strategy cannot fully consider the actual interference value of the current optical path, and the required number of FS belongs to the middle value, which is 28.4% and 28.2% lower than the full spectrum loading strategy of the two networks, respectively.
  • the present invention further evaluates the influence of optical fiber loss and effective area on the performance of optical path configuration. It can be seen that the number of FSs used decreases with decreasing fiber loss and increasing effective area because the former reduces ASE noise and the latter reduces NLI interference. As the fiber attenuation coefficient decreases, the number of FSs used decreases almost linearly. This finding is similar to the results in point-to-point systems, since this parameter mainly affects the gain of the amplifier, which in turn affects the ASE noise, and the spectral information of the optical path in the network. It doesn't matter much.
  • the present invention proposes a signal-to-noise ratio calculation model to evaluate the signal quality of the optical path.
  • the invention also proposes a spectrum allocation algorithm for OSNR perception and three optical path allocation strategies for OSNR performance guarantee.
  • the simulation results show that the spectrum-dependent ONSR performance guarantee strategy is the most effective, requires the least number of FSs, and can guarantee the ONSR requirements of each optical path.
  • the study found that although reducing the fiber loss can achieve better service performance, there is no need to prepare fibers with an effective area greater than 110 ⁇ m 2 .
  • the embodiments of the present application may be provided as a method, a system, or a computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.
  • computer-usable storage media including, but not limited to, disk storage, CD-ROM, optical storage, etc.
  • These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture comprising instruction means, the instructions
  • the apparatus implements the functions specified in the flow or flow of the flowcharts and/or the block or blocks of the block diagrams.

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Abstract

本发明涉及一种光通道性能保证下的OSNR感知频谱分配方法及系统，包括以下步骤：构建OSNR评估模型；获取源节点和目标节点之间的最短路径；获取多个调制格式及其对应的阈值，根据频谱效率对多个调制格式由高向低进行排序，获得排序后的调制格式列表；使用频谱效率最高的调制格式，基于带宽需求和FEC开销，计算出光路业务所需的带宽；将光路业务所需的带宽代入至OSNR评估模型中，获得业务实际所需的FS数；使用首次适应算法为所述最短路径分配当前业务所需要的频谱资源，获得当前业务在光路上的中心频率。其考虑可重构光分插复用器的级联效应，提出了一种光路信噪比估计模型，对于指导在EON中使用低损耗、大有效面积光纤具有重要意义。

Description

光通道性能保证下的OSNR感知频谱分配方法及系统 技术领域
本发明涉及光通信技术领域，尤其是指一种光通道性能保证下的OSNR感知频谱分配方法及系统。
背景技术
对于光传输系统来说，光纤的低损耗和大有效面积特性都可以改善性能。但是对于光纤厂商来说，制备具有低衰减系数、大有效面积的光纤将十分具有挑战性，成本也十分昂贵。文献N.Guo et al.,“Spectrum efficiency and cost evaluation for G.654.E fiber…,”in Proc.ACP 2020,paper M4A.274中公开，在点对点的光传输系统中，随着光纤衰减系数的减小，频谱效率将缓慢增长；随着光纤的有效面积从83μm 2增加到130μm 2，频谱效率将快速增长。
然而，现实中光纤是为网络提供光路服务，所以考虑到一个完整的网络拓扑时，点对点系统得到的结果并不能准确地反映低损耗和大有效面积光纤对网络中光信号传输带来的好处，传统的光信噪比评估模型不再准确。
发明内容
为此，本发明所要解决的技术问题在于克服现有技术中完整的网络拓扑时，点对点系统得到的结果并不能准确地反映低损耗和大有效面积光纤对网络中光信号传输带来的好处，传统的光信噪比评估模型不再准确的技术缺陷。
为解决上述技术问题，本发明提供了一种光通道性能保证下的OSNR感知频谱分配方法，包括以下步骤：
S1、构建OSNR评估模型以用于评估光路信号的传输质量，所述OSNR评估模型包括放大自发辐射噪声、非线性干扰和ROADM级联导致的滤波窄 化效应；
S2、发送光路业务需求，获取源节点和目标节点之间的最短路径；
S3、获取多个调制格式及其对应的阈值，根据频谱效率对多个调制格式由高向低进行排序，获得排序后的调制格式列表；
S4、使用频谱效率最高的调制格式，基于带宽需求和FEC开销，计算出光路业务所需的带宽；
S5、将光路业务所需的带宽代入至OSNR评估模型中，获得业务实际所需的FS数；
S6、使用首次适应算法为所述最短路径分配当前业务所需要的频谱资源，获得当前业务在光路上的中心频率。
作为优选的，所述使用首次适应算法为最短路径分配当前业务所需要的频谱资源，获得当前业务在光路上的中心频率，之后还包括：
分别使用全频谱加载策略、裕度预留策略和频谱依赖策略对OSNR质量进行评估，保证频谱分配后的光通道性能最佳。
作为优选的，使用全频谱加载策略对OSNR质量进行评估，包括：
在链路上所有的频谱资源都被占用，OSNR性能最差时，评估光路的传输质量OSNR；
当OSNR满足当前调制格式的阈值，建立光路并终止分配过程；否则，使用调制格式列表中当前调制格式的下一个调制格式，基于带宽需求和FEC开销，计算出光路业务所需的带宽，重复S5及其之后的步骤，直至所述光路业务需求建立；
在所有光路业务需求成功建立后，考虑非线性干扰并检查所有光路业务需求，重新计算OSNR是否还满足选择的调制格式，如果不满足当前调制格式，阻塞该业务。
作为优选的，使用裕度预留策略对OSNR质量进行评估，包括：
根据光线链路上当前的频谱资源的中心频率计算光路的传输质量OSNR；
预留裕度值M；
当(OSNR-M)满足当前调制格式的阈值，建立光路并终止分配过程，否则，使用调制格式列表中当前调制格式的下一个调制格式，基于带宽需求和FEC开销，计算出光路业务所需的带宽，重复S5及其之后的步骤，直至所述光路业务需求建立；
在所有光路业务需求成功建立后，考虑非线性干扰并检查所有光路业务需求，重新计算OSNR是否还满足选择的调制格式，如果不满足当前调制格式，阻塞该业务。
作为优选的，使用频谱依赖策略对OSNR质量进行评估，包括：
根据光线链路上当前的频谱资源的中心频率计算光路的传输质量OSNR；
当OSNR满足当前调制格式的阈值，建立光路并终止分配过程；否则，使用调制格式列表中当前调制格式的下一个调制格式，基于带宽需求和FEC开销，计算出光路业务所需的带宽，重复S5及其之后的步骤，直至所述光路业务需求建立；
在所有光路业务需求成功建立后，考虑非线性干扰并检查所有光路业务需求，重新计算OSNR是否还满足当前的调制格式；
若OSNR不满足当前的调制格式，则从失败的光路径开始，释放所有未 被检查的光路所使用的频谱资源；
对于失败的业务需求，降低使用的调制格式的级别，并沿着相同的最短路径重新分配频谱。
作为优选的，对于失败的业务需求，降低使用的调制格式的级别，并沿着相同的最短路径重新分配频谱，之后还包括：
对于没有检查过的光路，使用之前使用过的调制格式重新分配频谱，并检查是否能满足信噪比要求；
重复上述过程，直至所有新的光路成功建立后，所有光路都能满足信噪比。
作为优选的，所述S1包括：
当信号带宽是BW s，滤波器的3dB带宽为：
Figure PCTCN2021088324-appb-000001
其中，T是滤波器的插入损耗(以dB为单位)，N f是级联滤波器的数目，n是高斯函数的阶数；
光路的总信噪比OSNR lightpath为：
Figure PCTCN2021088324-appb-000002
其中，P in是光路的发射功率，P ASE是ASE噪声的功率值，P NLI是NLI干扰的功率值；
在每个光放大器都能恰好完全补偿前面信号的损耗的情况下，P ASE的计算公式为：
P ASE＝F×h×(G-1)×f i×B i              (3)
其中，F是光放大器的噪声系数，h是普朗克常量，G是光放大器的增益，f i是信号的中心频率，B i是信号的带宽；
对于非线性干扰，在加性高斯的假设下，P NLI可以计算为：
Figure PCTCN2021088324-appb-000003
其中，
Figure PCTCN2021088324-appb-000004
γ＝2π×n 2/(λ×A eff)，“asinh”是双曲反正弦函数，α是光纤衰减系数，β 2是二阶光纤色散系数，L span是跨段长度，跨段是指两个相邻光放大器之间的物理链路，λ是信号的波长，n 2是光纤的非线性折射率，A eff是光纤的有效面积。
作为优选的，所述S3中多个调制格式包括：PM-64QAM、PM-32QAM、PM-16QAM、PM-8QAM、PM-QPSK和PM-BPSK。
本发明公开了一种光通道性能保证下的OSNR感知频谱分配系统，包括：
OSNR构建模块，所述OSNR构建模块用于构建OSNR评估模型以用于评估光路信号的传输质量，所述OSNR评估模型包括放大自发辐射噪声、非线性干扰和ROADM级联导致的滤波窄化效应；
最短路径获取模块，所述最短路径获取模块用于发送光路业务需求，获取源节点和目标节点之间的最短路径；
调制格式排序模块，所述调制格式排序模块用于获取多个调制格式及其对应的阈值，根据频谱效率对多个调制格式由高向低进行排序，获得排序后的调制格式列表；
频谱分配模块，所述频谱分配模块使用频谱效率最高的调制格式，基于 带宽需求和FEC开销，计算出光路业务所需的带宽，将光路业务所需的带宽代入至OSNR评估模型中，获得业务实际所需的FS数，使用首次适应算法为所述最短路径分配当前业务所需要的频谱资源，获得当前业务在光路上的中心频率。
作为优选的，还包括：
OSNR质量评估模块，所述OSNR质量评估模块分别使用全频谱加载策略、裕度预留策略和频谱依赖策略对OSNR质量进行评估，保证频谱分配后的光通道性能最佳。
本发明的上述技术方案相比现有技术具有以下优点：
1、本发明在传统高斯噪声(GN)模型的基础上，考虑可重构光分插复用器(ROADM)的级联效应，提出了一种完整的光路信噪比(OSNR)估计模型。
2、本发明考虑到先前建立的光路和当前将要建立的光路之间的交叉信道干扰(XCI)，提出了三种频谱分配方案。仿真结果表明，所提出的频谱依赖策略是最有效的，此策略的频谱分配对每个光路都考虑到当前的XCI值。
3、与传统观点相反的是，本发明中，尽管降低光纤损耗总是有助于提高频谱效率，但是当有效面积超过110μm 2时，进一步增加有效面积并不能显著地提高频谱效率，这一发现对于指导在EON中使用低损耗、大有效面积光纤具有重要意义。
附图说明
图1为光通道性能保证下的OSNR感知频谱分配方法；
图2为光路的频谱资源示例图；
图3为测试网络图；
图4为OSNR性能保证策略的性能比较图；
图5为不同光纤类型的性能比较图，其中，(a)NSFNET；(b)USNET。
具体实施方式
下面结合附图和具体实施例对本发明作进一步说明，以使本领域的技术人员可以更好地理解本发明并能予以实施，但所举实施例不作为对本发明的限定。
参照图1所示，本发明公开了一种光通道性能保证下的OSNR感知频谱分配方法，包括以下步骤：
步骤一、构建OSNR评估模型以用于评估光路信号的传输质量，所述OSNR评估模型包括放大自发辐射噪声、非线性干扰和ROADM级联导致的滤波窄化效应，具体包括：
当信号带宽是BW s，滤波器的3dB带宽为：
Figure PCTCN2021088324-appb-000005
其中，T是滤波器的插入损耗(以dB为单位)，N f是级联滤波器的数目，n是高斯函数的阶数；
光路的总信噪比OSNR lightpath为：
Figure PCTCN2021088324-appb-000006
其中，P in是光路的发射功率，P ASE是ASE噪声的功率值，P NLI是NLI干扰的功率值；
在每个光放大器都能恰好完全补偿前面信号的损耗的情况下，P ASE的计算公式为：
P ASE＝F×h×(G-1)×f i×B i，               (3)
其中，F是光放大器的噪声系数，h是普朗克常量，G是光放大器的增益，f i是信号的中心频率，B i是信号的带宽；
对于非线性干扰，在加性高斯的假设下，P NLI可以计算为：
Figure PCTCN2021088324-appb-000007
其中，
Figure PCTCN2021088324-appb-000008
γ＝2π×n 2/(λ×A eff)，“asinh”是双曲反正弦函数，α是光纤衰减系数，β 2是二阶光纤色散系数，L span是跨段长度，跨段是指两个相邻光放大器之间的物理链路，λ是信号的波长，n 2是光纤的非线性折射率，A eff是光纤的有效面积。
步骤二、发送光路业务需求，获取源节点和目标节点之间的最短路径。
步骤三、获取多个调制格式及其对应的阈值，根据频谱效率对多个调制格式由高向低进行排序，获得排序后的调制格式列表。步骤三中多个调制格式包括：PM-64QAM、PM-32QAM、PM-16QAM、PM-8QAM、PM-QPSK和PM-BPSK。
步骤四、使用频谱效率最高的调制格式，基于带宽需求和FEC开销，计算出光路业务所需的带宽。
步骤五、将光路业务所需的带宽代入至OSNR评估模型中，获得业务实际所需的FS数。
步骤六、使用首次适应算法为所述最短路径分配当前业务所需要的频谱资源，获得当前业务在光路上的中心频率。
步骤七、分别使用全频谱加载策略、裕度预留策略和频谱依赖策略对 OSNR质量进行评估，保证频谱分配后的光通道性能最佳。
(1)使用全频谱加载策略对OSNR质量进行评估，包括：
在链路上所有的频谱资源都被占用，OSNR性能最差时，评估光路的传输质量OSNR；
当OSNR满足当前调制格式的阈值，建立光路并终止分配过程；否则，使用调制格式列表中当前调制格式的下一个调制格式，基于带宽需求和FEC开销，计算出光路业务所需的带宽，重复S5及其之后的步骤，直至所述光路业务需求建立；
在所有光路业务需求成功建立后，考虑非线性干扰并检查所有光路业务需求，重新计算OSNR是否还满足选择的调制格式，如果不满足当前调制格式，阻塞该业务。
(2)使用裕度预留策略对OSNR质量进行评估，包括：
根据光线链路上当前的频谱资源的中心频率计算光路的传输质量OSNR；
预留裕度值M；
当(OSNR-M)满足当前调制格式的阈值，建立光路并终止分配过程，否则，使用调制格式列表中当前调制格式的下一个调制格式，基于带宽需求和FEC开销，计算出光路业务所需的带宽，重复S5及其之后的步骤，直至所述光路业务需求建立；
在所有光路业务需求成功建立后，考虑非线性干扰并检查所有光路业务需求，重新计算OSNR是否还满足选择的调制格式，如果不满足当前调制格式，阻塞该业务。
(3)使用频谱依赖策略对OSNR质量进行评估，包括：
根据光线链路上当前的频谱资源的中心频率计算光路的传输质量OSNR；
当OSNR满足当前调制格式的阈值，建立光路并终止分配过程；否则，使用调制格式列表中当前调制格式的下一个调制格式，基于带宽需求和FEC开销，计算出光路业务所需的带宽，重复S5及其之后的步骤，直至所述光路业务需求建立；
在所有光路业务需求成功建立后，考虑非线性干扰并检查所有光路业务需求，重新计算OSNR是否还满足当前的调制格式；
若OSNR不满足当前的调制格式，则从失败的光路径开始，释放所有未被检查的光路所使用的频谱资源；
对于失败的业务需求，降低使用的调制格式的级别，并沿着相同的最短路径重新分配频谱；
对于没有检查过的光路，使用之前使用过的调制格式重新分配频谱，并检查是否能满足信噪比要求；
重复上述过程，直至所有新的光路成功建立后，所有光路都能满足信噪比。
本发明还公开了一种光通道性能保证下的OSNR感知频谱分配系统，包括OSNR构建模块、最短路径获取模块、调制格式排序模块、频谱分配模块和OSNR质量评估模块。
所述OSNR构建模块用于构建OSNR评估模型以用于评估光路信号的传输质量，所述OSNR评估模型包括放大自发辐射噪声、非线性干扰和ROADM级联导致的滤波窄化效应。
所述最短路径获取模块用于发送光路业务需求，获取源节点和目标节点 之间的最短路径。
所述调制格式排序模块用于获取多个调制格式及其对应的阈值，根据频谱效率对多个调制格式由高向低进行排序，获得排序后的调制格式列表。
所述频谱分配模块使用频谱效率最高的调制格式，基于带宽需求和FEC开销，计算出光路业务所需的带宽，将光路业务所需的带宽代入至OSNR评估模型中，获得业务实际所需的FS数，使用首次适应算法为所述最短路径分配当前业务所需要的频谱资源，获得当前业务在光路上的中心频率。
所述OSNR质量评估模块分别使用全频谱加载策略、裕度预留策略和频谱依赖策略对OSNR质量进行评估，保证频谱分配后的光通道性能最佳。
下面，结合具体实施例对本发明的技术方案做进一步说明。
一、OSNR评估模型
本发明利用OSNR来评估光路信号的传输质量，包括三个方面：放大自发辐射噪声(ASE)，非线性干扰(NLI)和ROADM级联导致的滤波窄化效应。当光路中信号经过一个ROADM时，代表着信号将会通过两个带通滤波器，而级联的ROADM滤波器将导致滤波带宽减少。通过将整个滤波器的通带拟合到一个高阶高斯函数，本发明将概况出级联滤波器的通带形状。如图2所示，如果信号带宽是BW s，滤波器的3dB带宽为：
Figure PCTCN2021088324-appb-000009
其中，T是滤波器的插入损耗(以dB为单位)，N f是级联滤波器的数目，n是高斯函数的阶数。此外，为了使光路中信号的功率保持一致，本发明需要光放大器如掺铒光纤放大器(EDFA)来增强光信号，这就引入了ASE噪声(如图2所示)。然后，光路的总信噪比OSNR lightpath可以计算为：
Figure PCTCN2021088324-appb-000010
其中，P in是光路的发射功率，P ASE是ASE噪声的功率值，P NLI是NLI干扰的功率值。本发明做出假设，每个光放大器都能恰好完全补偿前面信号的损耗，P ASE的计算公式为：
P ASE＝F×h×(G-1)×f i×B i        (3)
其中，F是光放大器的噪声系数，h是普朗克常量，G是光放大器的增益，f i是信号的中心频率，B i是信号的带宽。
对于非线性干扰，在加性高斯的假设下，P NLI可以计算为：
Figure PCTCN2021088324-appb-000011
其中
Figure PCTCN2021088324-appb-000012
γ＝2π×n 2/(λ×A eff)      (6)
公式(4)中，“asinh”是双曲反正弦函数，α是光纤衰减系数(单位是km -1)，β 2是二阶光纤色散系数，L span是跨段长度，跨段是指两个相邻光放大器之间的物理链路，λ是信号的波长，n 2是光纤的非线性折射率，A eff是光纤的有效面积。
从上面公式可以看出，ASE噪声主要与光纤衰减系数有关，而NLI干扰主要与光纤有效面积有关。
二、OSNR感知频谱分配
为了计算光路的信噪比，本发明首先需要知道光路的中心波长和带宽。因此，ONSR的计算与每个光路的频谱分配有关。而不同的频谱分配算法将导致不同的OSNR值，为此，本发明接下来介绍路由和频谱分配过程。
与以往算法相比，本发明提出的信噪比估计模型考虑了所有的损伤效应：ASE噪声、NLI干扰和级联ROADM滤波器导致的带宽窄化。后面两种损伤 与链路上的频谱信息有关，因此需要将信噪比估计与频谱分配过程结合起来。相比之下，传统算法认为ASE噪声是损伤的主要影响，与分配到光路的频谱无关，这是有缺陷的。
本发明的路由与频谱分配算法如下：
第1步、输入一个网络拓扑，一系列光路业务需求列表和一组调制格式。
第2步、对于每个需求，运行最短路径算法，找到它在需求的源节点和目标节点之间的路由。。
第3步、首先尝试最高调制格式，调制格式是PM-64QAM、PM-32QAM、PM-16QAM、PM-8QAM、PM-QPSK和PM-BPSK。
表1展示了不同调制格式的频谱效率和前向纠错编码(FEC)限制，注意到，这里的FEC限制值就是调制格式对应的OSNR阈值。
表1.不同调制格式的频谱效率和FEC限制
Figure PCTCN2021088324-appb-000013
基于带宽需求和FEC开销，计算出业务所需要的带宽BW s＝N s×f，其中f是网络中每个灵活栅格(FS)的带宽，N s是业务带宽所需要的FS的数目。
第4步、考虑到级联ROADM滤波器窄化信号带宽的影响，利用公式(1)计算出当前光路滤波器所需的带宽，然后计算出业务实际所需的FS数为
Figure PCTCN2021088324-appb-000014
第5步、使用首次命中策略为最短路径分配当前业务所需要的频谱资源，这将决定当前业务在光路上的中心频率。
第6步、评估光路的传输质量OSNR。如果OSNR满足当前调制格式的阈值，建立光路并终止分配过程，否则，转至第3步，考虑列表中的下一个调制格式。
三、OSNR性能保证策略
本发明考虑的是增量业务场景，每次只到达一个业务需求。当新的业务需求来临时，一条新的光路被设置，如果先前成功建立的某条光路与新光路经过了相同的链路和节点，那么新光路上所分配的频谱将对它的信号质量产生负面影响，这主要是由于光路之间存在交叉信道干扰(XCI)。多个光路之间也存在多信道干扰(MCI)，但MCI比XCI弱得多，因此本发明在这里将忽略MCI的影响。同时，共享链路或节点的其他光路的频谱中心频率和当前光路的中心频率越接近，带来的XCI影响越大。但是先前建立的某条光路如果与新光路没有经过相同的链路或节点，新光路的频谱分配将对此光路的信号质量没有任何影响。所以，为了成功建立一条新光路，除了保证新光路的信噪比满足阈值要求外，本发明还需要考虑之前建立的所有光路是否受到影响，是否还能满足所设置的OSNR阈值。因此，本发明提出了以下三个策略：
全频谱加载策略：假设所有链路的传输质量都是最坏的情况，也就是光信号传输的整个C波段都被占用，即全频谱加载，提前考虑存在的所有的XCI影响，这可以保证新的光路建立后不会再产生额外的XCI干扰。
裕度预留策略：从第一个光路业务需求开始，首先根据光纤链路上的当前频谱信息计算所建立光路的信噪比为OSNR current。考虑到后面光路请求潜在的XCI效应，在为当前光路选择调制格式时先预留了一个OSNR裕度值，也就是要求OSNR current-M≥FEC limit，其中M是设置的裕度值，FEC limit是调制格式所需的OSNR阈值。其中裕度值是通过测试确定的，能够保证以后所有的光路请求都能成功建立。
频谱依赖策略：这种策略比前两种策略更先进，但代价是更高的计算复杂度。为了成功建立新的光路LP new，首先为LP new分配频谱资源，然后本发明会检查之前已经成功建立的光路列表{LP pre}，观察列表中与LP new共享链路的光路是否还能满足各自的OSNR阈值。如果任何一个光路径失败，那么本发明从失败的光路径开始，释放所有未被检查的光路所使用的频谱资源。然后，对于失败的业务需求，本发明降低使用的调制格式的级别，并沿着相同的路由重新分配频谱。对于没有检查过的光路，本发明会使用之前使用过的调制格式重新分配频谱给它们，并检查它们是否能满足信噪比要求。本发明重复这个过程，直到新的光路成功建立后，所有的光路都能满足它们的信噪比要求。
四、仿真和性能分析
表2
Figure PCTCN2021088324-appb-000015
本发明考虑了如表2所示的三种不同类型的光纤，分别是G.652，G.654.E-A110和G.654.E-A130。在弹性光网络中，为了评估提出的三种不同的OSNR保证策略的性能，同时评估光纤的衰减系数和有效面积如何影响光路服务配置性能，本发明将采用14个节点、21条链路的NSFNET网络和24个节点、43条链路的USNET网络作为本发明的测试网络。具体测试网络如 图3所示，链路距离以km为单位。在这里本发明假设每个节点对之间都存在一个业务流量需求，并且每次都增量地提供一个需求。每个业务的带宽需求均匀分布在[120，X]Gb/s的范围内，其中X是带宽需求的最大值，在NSFNET和USNET网络中X分别设置为700和300。假设每个FS的带宽是12.5GHz，FEC的开销是25％。在裕度预留策略中，NSFNET和USNET网络的裕度值分别设置为1.5dB和2dB，因为USNET网络比NSFNET网络更大更复杂，所以裕度值设置地更大一点。另外，EDFA的噪声系数将设置为5.5dB，每条光路的发射功率是0dBm。
如图4所示，本发明首先比较了三种OSNR性能保证策略的性能。其中光纤参数设置如下：衰减系数为0.185dB/km，有效面积为83μm 2。因为全频谱加载策略考虑了所有光纤链路的最坏情况，每条光路的信噪比都被低估，因此分配的调制格式级别较低，需要的频谱资源也更多。相比之下，由于频谱依赖策略只考虑来自当前光路频谱的干扰，因此实际受到的干扰将低于全频谱加载策略的结果，这样可以计算出更高的信噪比，从而实现更有效的频谱资源分配，使用的FS数目也是最少，比NSFNET和USNET全频谱加载策略下的结果分别降低了40.8％和38.9％。虽然裕度预留策略也只考虑了来自当前光路频谱的干扰，但此策略对每个光路使用相同的信噪比惩罚。因此，该策略不能充分考虑当前光路的实际干扰值，需要的FS数目属于中间值，比两个网络的全频谱加载策略分别降低了28.4％和28.2％。
基于频谱依赖策略，如图5所示，本发明进一步评估光纤损耗和有效面积对光路配置性能的影响。可以看到，所使用的FS数量随着光纤损耗的降低和有效面积的增加而减少，这是因为前者可以降低ASE噪声，而后者可以减小NLI干扰。当光纤衰减系数减小时，所使用的FS数量几乎呈线性下降，这个发现与点对点系统中的结果是相似的，因为这个参数主要影响放大器的增益，进而影响ASE噪声，与网络中光路的频谱信息关系不大。相比之下，随着有效面积的增加，所使用的FS数目呈现饱和趋势，特别是从110μm 2到130μm 2。 主要有两点原因：(1)有效面积与OSNR的对数关系；(2)在频谱依赖策略下，链路上的频谱并不是满负荷状态，因此XCI的改善将随着有效面积的增加而减小。这一结果对于光纤的制备是非常有用的，因为从网络性能的角度来看，这意味着制备衰减系数尽可能低的光纤非常重要，但是有效面积超过110μm 2后不必再继续增加。
综上所述，为了评估光纤损耗和有效面积对EON中光路服务配置的影响，本发明提出了一种信噪比计算模型来评估光路的信号质量。本发明还提出了一种OSNR感知的频谱分配算法和三种OSNR性能保证的光路分配策略。仿真结果表明，频谱依赖的ONSR性能保证策略是最有效的，需要最少的FS数量，并能够保证每个光路的ONSR需求。研究发现，虽然降低光纤损耗可以获得较好的业务性能，但无需制备有效面积大于110μm 2的光纤。
本领域内的技术人员应明白，本申请的实施例可提供为方法、系统、或计算机程序产品。因此，本申请可采用完全硬件实施例、完全软件实施例、或结合软件和硬件方面的实施例的形式。而且，本申请可采用在一个或多个其中包含有计算机可用程序代码的计算机可用存储介质(包括但不限于磁盘存储器、CD-ROM、光学存储器等)上实施的计算机程序产品的形式。
本申请是参照根据本申请实施例的方法、设备(系统)、和计算机程序产品的流程图和/或方框图来描述的。应理解可由计算机程序指令实现流程图和/或方框图中的每一流程和/或方框、以及流程图和/或方框图中的流程和/或方框的结合。可提供这些计算机程序指令到通用计算机、专用计算机、嵌入式处理机或其他可编程数据处理设备的处理器以产生一个机器，使得通过计算机或其他可编程数据处理设备的处理器执行的指令产生用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的装置。
这些计算机程序指令也可存储在能引导计算机或其他可编程数据处理 设备以特定方式工作的计算机可读存储器中，使得存储在该计算机可读存储器中的指令产生包括指令装置的制造品，该指令装置实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能。
这些计算机程序指令也可装载到计算机或其他可编程数据处理设备上，使得在计算机或其他可编程设备上执行一系列操作步骤以产生计算机实现的处理，从而在计算机或其他可编程设备上执行的指令提供用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的步骤。
显然，上述实施例仅仅是为清楚地说明所作的举例，并非对实施方式的限定。对于所属领域的普通技术人员来说，在上述说明的基础上还可以做出其它不同形式变化或变动。这里无需也无法对所有的实施方式予以穷举。而由此所引伸出的显而易见的变化或变动仍处于本发明创造的保护范围之中。

Claims (10)

  1. 一种光通道性能保证下的OSNR感知频谱分配方法，其特征在于，包括以下步骤：
    S1、构建OSNR评估模型以用于评估光路信号的传输质量，所述OSNR评估模型包括放大自发辐射噪声、非线性干扰和ROADM级联导致的滤波窄化效应；
    S2、发送光路业务需求，获取源节点和目标节点之间的最短路径；
    S3、获取多个调制格式及其对应的阈值，根据频谱效率对多个调制格式由高向低进行排序，获得排序后的调制格式列表；
    S4、使用频谱效率最高的调制格式，基于带宽需求和FEC开销，计算出光路业务所需的带宽；
    S5、将光路业务所需的带宽代入至OSNR评估模型中，获得业务实际所需的FS数；
    S6、使用首次适应算法为所述最短路径分配当前业务所需要的频谱资源，获得当前业务在光路上的中心频率。
  2. 根据权利要求1所述的光通道性能保证下的OSNR感知频谱分配方法，其特征在于，所述使用首次适应算法为最短路径分配当前业务所需要的频谱资源，获得当前业务在光路上的中心频率，之后还包括：
    分别使用全频谱加载策略、裕度预留策略和频谱依赖策略对OSNR质量进行评估，保证频谱分配后的光通道性能最佳。
  3. 根据权利要求2所述的光通道性能保证下的OSNR感知频谱分配方法， 其特征在于，使用全频谱加载策略对OSNR质量进行评估，包括：
    在链路上所有的频谱资源都被占用，OSNR性能最差时，评估光路的传输质量OSNR；
    当OSNR满足当前调制格式的阈值，建立光路并终止分配过程；否则，使用调制格式列表中当前调制格式的下一个调制格式，基于带宽需求和FEC开销，计算出光路业务所需的带宽，重复S5及其之后的步骤，直至所述光路业务需求建立；
    在所有光路业务需求成功建立后，考虑非线性干扰并检查所有光路业务需求，重新计算OSNR是否还满足选择的调制格式，如果不满足当前调制格式，阻塞该业务。
  4. 根据权利要求2所述的光通道性能保证下的OSNR感知频谱分配方法，其特征在于，使用裕度预留策略对OSNR质量进行评估，包括：
    根据光线链路上当前的频谱资源的中心频率计算光路的传输质量OSNR；
    预留裕度值M；
    当(OSNR-M)满足当前调制格式的阈值，建立光路并终止分配过程，否则，使用调制格式列表中当前调制格式的下一个调制格式，基于带宽需求和FEC开销，计算出光路业务所需的带宽，重复S5及其之后的步骤，直至所述光路业务需求建立；
    在所有光路业务需求成功建立后，考虑非线性干扰并检查所有光路业务需求，重新计算OSNR是否还满足选择的调制格式，如果不满足当前调制格式，阻塞该业务。
  5. 根据权利要求2所述的光通道性能保证下的OSNR感知频谱分配方法， 其特征在于，使用频谱依赖策略对OSNR质量进行评估，包括：
    根据光线链路上当前的频谱资源的中心频率计算光路的传输质量OSNR；
    当OSNR满足当前调制格式的阈值，建立光路并终止分配过程；否则，使用调制格式列表中当前调制格式的下一个调制格式，基于带宽需求和FEC开销，计算出光路业务所需的带宽，重复S5及其之后的步骤，直至所述光路业务需求建立；
    在所有光路业务需求成功建立后，考虑非线性干扰并检查所有光路业务需求，重新计算OSNR是否还满足当前的调制格式；
    若OSNR不满足当前的调制格式，则从失败的光路径开始，释放所有未被检查的光路所使用的频谱资源；
    对于失败的业务需求，降低使用的调制格式的级别，并沿着相同的最短路径重新分配频谱。
  6. 根据权利要求5所述的光通道性能保证下的OSNR感知频谱分配方法，其特征在于，对于失败的业务需求，降低使用的调制格式的级别，并沿着相同的最短路径重新分配频谱，之后还包括：
    对于没有检查过的光路，使用之前使用过的调制格式重新分配频谱，并检查是否能满足信噪比要求；
    重复上述过程，直至所有新的光路成功建立后，所有光路都能满足信噪比。
  7. 根据权利要求1所述的光通道性能保证下的OSNR感知频谱分配方法，其特征在于，所述S1包括：
    当信号带宽是BW s，滤波器的3dB带宽为：
    Figure PCTCN2021088324-appb-100001
    其中，T是滤波器的插入损耗(以dB为单位)，N f是级联滤波器的数目，n是高斯函数的阶数；
    光路的总信噪比OSNR lightpath为：
    Figure PCTCN2021088324-appb-100002
    其中，P in是光路的发射功率，P ASE是ASE噪声的功率值，P NLI是NLI干扰的功率值；
    在每个光放大器都能恰好完全补偿前面信号的损耗的情况下，P ASE的计算公式为：
    P ASE＝F×h×(G-1)×f i×B i  (3)
    其中，F是光放大器的噪声系数，h是普朗克常量，G是光放大器的增益，f i是信号的中心频率，B i是信号的带宽；
    对于非线性干扰，在加性高斯的假设下，P NLI可以计算为：
    Figure PCTCN2021088324-appb-100003
    其中，
    Figure PCTCN2021088324-appb-100004
    γ＝2π×n 2/(λ×A eff)，“asinh”是双曲反正弦函数，α是光纤衰减系数，β 2是二阶光纤色散系数，L span是跨段长度，跨段是指两个相邻光放大器之间的物理链路，λ是信号的波长，n 2是光纤的非线性折射率，A eff是光纤的有效面积。
  8. 根据权利要求1所述的光通道性能保证下的OSNR感知频谱分配方法，其特征在于，所述S3中多个调制格式包括：
    PM-64QAM、PM-32QAM、PM-16QAM、PM-8QAM、PM-QPSK和PM-BPSK。
  9. 一种光通道性能保证下的OSNR感知频谱分配系统，其特征在于，包括：
    OSNR构建模块，所述OSNR构建模块用于构建OSNR评估模型以用于评估光路信号的传输质量，所述OSNR评估模型包括放大自发辐射噪声、非线性干扰和ROADM级联导致的滤波窄化效应；
    最短路径获取模块，所述最短路径获取模块用于发送光路业务需求，获取源节点和目标节点之间的最短路径；
    调制格式排序模块，所述调制格式排序模块用于获取多个调制格式及其对应的阈值，根据频谱效率对多个调制格式由高向低进行排序，获得排序后的调制格式列表；
    频谱分配模块，所述频谱分配模块使用频谱效率最高的调制格式，基于带宽需求和FEC开销，计算出光路业务所需的带宽，将光路业务所需的带宽代入至OSNR评估模型中，获得业务实际所需的FS数，使用首次适应算法为所述最短路径分配当前业务所需要的频谱资源，获得当前业务在光路上的中心频率。
  10. 如权利要求9所述的光通道性能保证下的OSNR感知频谱分配方法，其特征在于，还包括：
    OSNR质量评估模块，所述OSNR质量评估模块分别使用全频谱加载策略、裕度预留策略和频谱依赖策略对OSNR质量进行评估，保证频谱分配后的光通道性能最佳。
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