Multi-band optical switching architecture supporting wavelength conversion at partial ports

Abstract

The invention relates to the technical field of optical switching, and discloses a multiband optical switching architecture supporting wavelength conversion at part of ports, comprising: ports for configuring a wavelength converter, including a demultiplexer or multiplexer, an optical amplifier working at different wavebands, a wavelength converter and a wavelength selection switch working at a C waveband; the port without the wavelength converter comprises a demultiplexer or a multiplexer, an optical amplifier working in different wavebands and a wavelength selection switch working in different wavebands; when an optical signal enters, routing is realized through the demultiplexer and other devices; when the optical signal is output, the optical signal is output to the optical fiber through the multiplexer and other devices. And the network controller is used for carrying out routing and wavelength distribution in combination with signal-to-noise ratio damage brought by the introduced wavelength converter. According to the invention, cost and blocking probability can be reduced, and signal transmission quality and expansion capability can be improved.

Description

Technical Field

[0001] The present invention relates to the field of optical switching technology, and in particular to a multi-band optical switching architecture that supports wavelength conversion at some ports. Background Art

[0002] With the growing demand for bandwidth-intensive applications, optical network capacity expansion has become a critical issue. The expansion of the S+C+L band (including the S-band, C-band, and L-band) maximizes fiber utilization and reduces capital expenditures. To achieve an efficient transition from the C-band to the S+C+L band, an architecture that can implement a multi-band optical cross-connect (MB-OXC) is required.

[0003] like Figure 1 As shown, the conventional multi-band optical cross-connect (MB-OXC) architecture consists of multi-band multiplexers / demultiplexers, optical amplifiers, and wavelength selective switches (WSSs) operating in different bands. Optical components are designed for each new band to support optical signal routing in different bands (for details, see the paper "A. Napoli, N. Calabretta, J.K. Fischer, N. Costa, S. Abrate, J. Pedro, "Perspectives of Multi-band Optical Communication Systems," 2018 23rd Opto-Electronics and Communications Conference (OECC), Jeju, Korea (South), 2018, pp. 1-2, DOI: 10.1109 / OECC.2018.8730026"). However, this architecture requires the deployment of new optical components for each new band, preventing the reuse of existing C-band component resources and increasing costs. At the same time, this architecture does not support wavelength conversion and is therefore limited by wavelength continuity constraints, resulting in low utilization efficiency of spectrum resources and increasing the probability of blocking when processing actual business requests.

[0004] In order to reduce the dependence on special devices for new bands and alleviate the problem of wavelength continuity, such as Figure 2The multi-band optical switching architecture (WSBS MB-OXC) supporting wavelength selection and band switching shown in the paper "H.Kawahara, M.Nakagawa, T.Seki and T.Miyamura,"Experimental Demonstration of Wavelength-Selective Band / Direction-Switchable Multi-Band OXC Using an Inter-Band All-Optical Wavelength Converter", 2020 European Conference on Optical Communications (ECOC), Brussels, Belgium, 2020, pp. 1-4, DOI: 10.1109 / ECOC48923.2020.9333270") introduces an all-optical wavelength converter (AO-WC) that can convert the wavelengths of the S-band and L-band to the C-band, thereby using the C-band WSS to achieve wavelength switching between all bands. However, this architecture also has disadvantages: First, this architecture requires that all S-band and L-band wavelengths must be converted to C-band through a wavelength converter before switching, which causes the number of wavelength converters to increase linearly with the number of ports, which directly increases the cost and system complexity; second, each wavelength conversion will introduce a certain amount of optical signal transmission loss, and an optical path may need to pass through multiple wavelength converters, significantly reducing the signal transmission quality; finally, this architecture relies on a high-port-count C-band wavelength selective switch (WSS), however, the physical implementation of a high-port-count WSS has technical bottlenecks, for example, the paper "T.Ye, J.Luo, H.Li and Y.Yao,"Design ofLarge-Scale OXC for the Next-Generation ROADM", 2024 Conference on Lasers and Electro-Optics Pacific Rim (CLEO-PR), Incheon, Korea, Republic of,2024,pp.1-2,DOI:10.1109 / CLEO-PR60912.2024.10676781” points out that it is extremely difficult to expand the number of ports of 1×K WSS to more than 1×48, which not only limits the expansion of node scale, but also affects the scalability of the network, making it difficult for this architecture to meet the needs of future large-scale multi-band optical networks. Summary of the Invention

[0005] To this end, the technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a multi-band optical switching architecture that supports wavelength conversion at some ports, which can reduce costs and blocking probability, and improve signal transmission quality and expansion capabilities.

[0006] To solve the above technical problems, the present invention provides a multi-band optical switching architecture that supports wavelength conversion at some ports, including:

[0007] The ports configured with wavelength converters include a demultiplexer or multiplexer, optical amplifiers operating in different wavelength bands, a wavelength converter, and a wavelength selective switch operating in the C-band. When an optical signal enters, it is routed sequentially through the demultiplexer, optical amplifiers operating in different wavelength bands, a wavelength converter, and a wavelength selective switch operating in the C-band. When an optical signal is output, it is sequentially routed through the wavelength converter, optical amplifiers operating in different wavelength bands, and the multiplexer to the optical fiber.

[0008] Ports without wavelength converters include demultiplexers or multiplexers, optical amplifiers operating in different wavelength bands, and wavelength selective switches operating in different wavelength bands. When an optical signal enters, it is routed sequentially through the demultiplexer, optical amplifiers operating in different wavelength bands, and wavelength selective switches operating in different wavelength bands. When an optical signal is output, it is output to the optical fiber through optical amplifiers and multiplexers operating in different wavelength bands.

[0009] The network controller performs routing and wavelength allocation in combination with the signal-to-noise ratio impairment caused by the introduction of wavelength converters.

[0010] Furthermore, routing is achieved sequentially through a demultiplexer, an optical amplifier operating in different wavelength bands, a wavelength converter, and a wavelength selective switch operating in the C band. Specifically, the wavelengths of different wavelength bands are separated by the demultiplexer, and the optical signals of each separated wavelength band are subjected to loss compensation by the optical amplifier of the corresponding wavelength band. The optical signals of the S band and the L band are converted into optical signals of the C band by the wavelength converter, and all wavelengths of the C band are routed by the wavelength selective switch operating in the C band.

[0011] The optical signal is sequentially output to the optical fiber through a wavelength converter, an optical amplifier operating in different wavelength bands, and a multiplexer. Specifically, the optical signal is converted into an S-band optical signal or an L-band optical signal by the wavelength converter, the optical signal after the wavelength conversion is compensated for loss by an optical amplifier of the corresponding wavelength band, and the compensated optical signal is multiplexed into all wavelengths by the multiplexer and output to the optical fiber;

[0012] The routing is achieved in sequence through a demultiplexer, an optical amplifier operating in different wavelength bands, and a wavelength selective switch operating in different wavelength bands. Specifically, the wavelengths of different wavelength bands are separated by the demultiplexer, and the optical signals of each separated wavelength band are compensated for loss by the optical amplifier of the corresponding wavelength band. The wavelengths of different wavelength bands are routed by the wavelength selective switch operating in different wavelength bands.

[0013] The optical amplifiers and multiplexers operating in different wavelength bands are used to output the optical signals to the optical fiber. Specifically, the optical amplifiers in the corresponding wavelength bands are used to compensate for the loss, and the compensated optical signals are multiplexed into all wavelengths through the multiplexer and output to the optical fiber.

[0014] Furthermore, routing and wavelength allocation are performed in combination with the signal-to-noise ratio impairment caused by the introduction of wavelength converters. The specific process of routing and wavelength allocation is as follows:

[0015] Acquire the new service that has arrived and search for the virtual link between the source and destination nodes of the new service. Determine whether the virtual link exists and has sufficient capacity. If so, configure the new service through the virtual link and update the remaining capacity on the link. Otherwise, perform the steps of finding K shortest paths for the new service.

[0016] Find K shortest paths for the new service. Under the condition of wavelength continuity, find available optical fibers for each link along the path and check the availability of transmitters, receivers, and nodes. If available, add the optical path to the candidate optical channel. The optical path is an end-to-end optical signal transmission channel established along a wavelength on each intermediate link in the path from the source node to the destination node. Determine whether a candidate optical channel exists. If not, perform the step of finding K shortest paths for the new service again. If yes, perform the step of selecting an optical channel based on bandwidth requirements and signal-to-noise ratio degradation caused by the introduction of wavelength converters.

[0017] Again, K shortest paths are found for the new service. If wavelength continuity is not met, a recursive and backtracking algorithm is used to find available fiber and idle wavelengths for each link on the path. The availability of transmitters, receivers, and nodes is checked. If available, the optical path is added to the candidate optical channel. A check is again made to determine whether a candidate optical channel exists. If not, the new service is blocked. If yes, the optical channel selection step is performed based on bandwidth requirements and the signal-to-noise ratio degradation caused by the introduction of wavelength converters.

[0018] Select an optical channel based on bandwidth requirements and signal-to-noise ratio degradation caused by the introduction of a wavelength converter, and use the selected optical channel as a new virtual link; if all candidate optical channels cannot be used as the new virtual link, determine whether the step of searching for K shortest paths for the new service has been performed again; if not, perform the step of searching for K shortest paths for the new service again; otherwise, block the new service;

[0019] The highest-order modulation format available is selected based on the new virtual link, new services are configured through the new virtual link, and the remaining capacity on the link is updated.

[0020] Furthermore, the optical channel is selected based on bandwidth requirements and signal-to-noise ratio damage caused by the introduction of a wavelength converter, specifically:

[0021] The generalized signal-to-noise ratio (SNR) of each candidate optical channel is calculated by comprehensively considering the SNR impairment caused by wavelength converters, the spontaneous emission noise introduced by optical amplifiers, the nonlinear interference during fiber transmission, and stimulated Raman scattering. Based on the correspondence between the generalized SNR and modulation format of each candidate optical channel, the highest-order modulation format that can be used for the optical channel is determined, thereby determining the maximum transmission capacity of the optical channel. The optical channel with the highest generalized SNR among the links through which the optical channel with a transmission capacity not less than the service bandwidth requirement passes is selected as the new virtual link.

[0022] Furthermore, the generalized signal-to-noise ratio of each of the candidate optical channels is calculated as follows:

[0023]

[0024] Among them, GSNR lightpath Represents the generalized signal-to-noise ratio of the optical channel, GSNR l WC represents the generalized signal-to-noise ratio of the lth link through which the optical channel L passes. penalty represents the signal-to-noise ratio loss introduced by a single wavelength converter, k represents the number of wavelength converters configured on the optical channel, and L represents the set of all links on the optical channel;

[0025] The transmission capacity is not less than the generalized signal-to-noise ratio of the link through which the optical channel of the service bandwidth requirement passes, and the calculation method is:

[0026]

[0027] Furthermore, the generalized signal-to-noise ratio of the lth link through which the optical channel L passes is calculated as follows:

[0028]

[0029] Among them, f i is the center frequency of the ith channel, P i is the channel transmit power, P ASE (f i ) is the spontaneous emission noise power accumulated by the optical signal on the lth link, P NLI (f i ) is the nonlinear interference power accumulated by the optical signal on the lth link.

[0030] Furthermore, the spontaneous emission noise power accumulated by the optical signal on the lth link is calculated as follows:

[0031]

[0032] Among them, F(f i ) represents the noise coefficient of the i-th channel, h represents the Planck constant, B i represents the bandwidth of the i-th channel, G post Represents the gain of the post-amplifier, G eff,m (f i ) represents the gain of the mth deployed line amplifier or preamplifier, N s Indicates the number of zoom spans.

[0033] Furthermore, the nonlinear interference power accumulated by the optical signal on the lth link is calculated as follows:

[0034] P NLI (f i )=B i ·G NLI (f i ),

[0035] Among them, B i represents the bandwidth of the i-th channel, G NLI (f i ) represents the power spectral density of the nonlinear interference of the i-th channel.

[0036] Furthermore, the power spectral density of the nonlinear interference of the i-th channel is calculated as follows:

[0037]

[0038] Where γ represents the fiber nonlinear coefficient, N s Indicates the number of magnified spans, G Tx (f i ) represents the power spectrum density of the i-th channel transmission power, f1+f2-f i represents the new channel generated by the four-wave mixing intermodulation phenomenon between the first channel, the second channel and the i-th channel, ρ(z,f) is the normalized amplitude profile function, d is the length of the amplification span, Φ(f1,f2,f i,z )=-4π 2 (f1-f i )(f2-f i )[β2+πβ3(f1+f2)]z, β2 represents the second-order dispersion coefficient, and β3 represents the third-order dispersion coefficient.

[0039] Furthermore, the normalized amplitude profile function is expressed as:

[0040]

[0041] where g(ξ,f) is a function of the fiber's loss and stimulated Raman scattering effect with respect to the fiber's spatial coordinate ξ and frequency f.

[0042] The above technical solution of the present invention has the following beneficial effects compared with the prior art:

[0043] The present invention configures wavelength converters at a certain ratio on ports, enabling some ports to support inter-band conversion. This significantly reduces the number of wavelength converters and wavelength selective switch ports required when all wavelength converters are configured, effectively reducing costs while maintaining a low blocking probability and improving the scalability of the optical switching architecture. At the same time, by combining the signal-to-noise ratio impairment caused by the introduction of wavelength converters for routing and wavelength allocation, the signal transmission quality of the optical switching architecture is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0045] Figure 1 A schematic diagram of the structure of an architecture in which optical components are designed for each new wavelength band to support optical signal routing in different wavelength bands in the prior art.

[0046] Figure 2 The diagram is a structural diagram of a multi-band optical switching architecture that supports wavelength selection and band switching in the prior art.

[0047] Figure 3 Schematic diagram of the structure of a multi-band optical switching architecture supporting wavelength conversion at some ports in a preferred embodiment of the present invention.

[0048] Figure 4 Schematic diagram of a network controller in a preferred embodiment of the present invention.

[0049] Figure 5 Flowchart of the routing and wavelength allocation method in a preferred embodiment of the present invention.

[0050] Figure 6 This is a network topology diagram used in the simulation experiment in the preferred embodiment of the present invention.

[0051] Figure 7 This is a comparison chart of the blocking performance of different architectures in the network in the simulation experiment in the preferred embodiment of the present invention.

[0052] Figure 8This is a relationship diagram between architecture cost and blocking probability corresponding to different configuration ratios of wavelength converter ports when the present invention is used in a simulation experiment in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0053] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0054] Reference Figure 3 As shown, the present invention discloses a multi-band optical switching architecture that supports wavelength conversion at some ports, including two different ports and a network controller, the two different ports being ports configured with wavelength converters and ports not configured with wavelength converters.

[0055] The ports configured with wavelength converters include demultiplexers (DEMUXs) or multiplexers (MUXs), optical amplifiers operating in different wavelength bands, wavelength converters (WCs), and wavelength selective switches (WSSs) operating in the C-band. When an optical signal enters, it is routed sequentially through the demultiplexer, optical amplifiers operating in different wavelength bands, wavelength converters, and wavelength selective switches operating in the C-band. When an optical signal exits, it is sequentially routed through the wavelength converter, optical amplifiers operating in different wavelength bands, and the multiplexer into the optical fiber. Specifically, when an optical signal enters, the demultiplexer separates the wavelengths of different wavelength bands. Each separated optical signal passes through the corresponding optical amplifier for loss compensation. The S-band and L-band optical signals are converted to C-band optical signals by the wavelength converter (C-band optical signals do not need to pass through the wavelength converter). All C-band wavelengths are routed through the wavelength selective switch operating in the C-band. When the optical signal is output, if the wavelength selective switch working in the C band is connected to the wavelength converter, the wavelength converter will convert the optical signal into an S band optical signal or an L band optical signal. The converted optical signal passes through the optical amplifier of the corresponding band for loss compensation. The compensated optical signal passes through the multiplexer to multiplex all wavelengths and output to the optical fiber.

[0056] An input-stage WSS can only be connected to an output-stage WSS with the same operating band. Therefore, in the present invention, if an S-band or L-band signal enters a port without a converter, it cannot be switched to a port with a converter, which to some extent limits the network's switching flexibility. However, by properly utilizing ports without wavelength conversion capabilities, unnecessary wavelength conversion can be effectively avoided, thereby reducing network construction costs and minimizing the damage to the generalized signal-to-noise ratio (GSNR) caused by frequent conversions. The present invention achieves a good balance between cost and performance by optimizing the ratio of the two types of ports.

[0057] Ports without wavelength converters include demultiplexers or multiplexers, optical amplifiers operating in different wavelength bands, and wavelength selective switches operating in different wavelength bands. When an optical signal enters, it is routed sequentially through the demultiplexer, optical amplifiers operating in different wavelength bands, and wavelength selective switches operating in different wavelength bands. When an optical signal is output, it is output to the optical fiber through optical amplifiers and multiplexers operating in different wavelength bands. Specifically, when an optical signal enters, the demultiplexer separates the wavelengths of different wavelength bands. After separation, the optical signal of each wavelength band passes through the optical amplifier of the corresponding wavelength band for loss compensation. The wavelengths of different wavelength bands are then routed through the wavelength selective switches operating in different wavelength bands. When an optical signal is output, the optical signal does not need to undergo wavelength conversion and directly passes through the optical amplifier of the corresponding wavelength band for loss compensation. The compensated optical signal is multiplexed into all wavelengths by the multiplexer and output to the optical fiber.

[0058] The network controller performs routing and wavelength allocation in combination with the signal-to-noise ratio loss caused by the introduction of wavelength converters. Figure 4 As shown, the network controller is used to control the entire network. It can monitor the transmission quality (QoT) of different channels of all links in the network in real time, and is responsible for routing and wavelength allocation, as well as the configuration of wavelength selective switches in the multi-band optical switching architecture.

[0059] like Figure 5 As shown in Figure 2, the routing and wavelength assignment process is as follows:

[0060] Step 1: Obtain the new service that has arrived and search for the virtual link between the source node and the destination node of the new service. Determine whether the virtual link exists and has sufficient capacity. If so, configure the new service through the virtual link and update the remaining capacity on the link to complete the allocation and proceed to step 6. Otherwise, proceed to step 2.

[0061] Step 2: Find K shortest paths for the new service (K = 3 in this embodiment); under the condition of wavelength continuity (wavelength conversion is allowed within the node, but the optical signal must use the same wavelength when entering and leaving the node), scan all wavelengths and find an available optical fiber for each link on the path (available optical fiber means that the given wavelength on this optical fiber is idle). Check the availability of the transmitter, receiver, and node. If available, add the optical path to the candidate optical channel (i.e., an optical channel that can be established). The optical path is an end-to-end optical signal transmission channel established along a wavelength on each intermediate link in the path from the source node to the destination node; determine whether there is a candidate optical channel. If not, execute step 3; if so, execute step 4.

[0062] Step 3: Find K shortest paths for the new service again. If wavelength continuity is not met, use a recursive and backtracking algorithm to find available optical fibers and idle wavelengths for each link on the path (satisfying inter-band wavelength conversion). Check the availability of transmitters, receivers, and nodes. If available, add the optical path to the candidate optical channel. Again, determine whether a candidate optical channel exists. If not, block the new service and execute step 6. If yes, execute step 4.

[0063] Step 4: Select an optical channel based on bandwidth requirements and the signal-to-noise ratio degradation caused by the introduction of wavelength converters. The selected optical channel is used as the new virtual link, and step 5 is executed. If none of the candidate optical channels can be used as the new virtual link, step 3 is determined to determine whether it has been executed. If not, step 3 is executed; otherwise, the new service is blocked and step 6 is executed. The generalized signal-to-noise ratio is used to evaluate the transmission quality (QoT) of the optical channel, thereby implementing routing and wavelength allocation.

[0064] Taking into account the signal-to-noise ratio damage caused by the wavelength converter, the spontaneous emission noise (ASE) introduced by the optical amplifier, the nonlinear interference (NLI) and stimulated Raman scattering (SRS) during the fiber transmission process, the generalized signal-to-noise ratio (GSNR) of each optical channel in the candidate optical channel is calculated. lightpath , the calculated GSNR lightpath The range is compared with the corresponding relationship between the highest order modulation format that can be used to obtain the highest order modulation format that can be used for the optical channel, and then the maximum transmission capacity of the optical channel, GSNR, is obtained. lightpath The corresponding relationship between the range, the highest order modulation format that can be used, and the spectrum efficiency (i.e., the maximum amount of information that can be transmitted within a unit bandwidth) is shown in Table 1. lightpath If the value is too low, no modulation format can be selected. At this time, all candidate optical channels cannot be used as new virtual links. Determine whether step 3 has been executed. If not, execute step 3. Otherwise, block the new service and execute step 6.

[0065] Table 1 GSNR lightpath Correspondence table with the highest-order modulation format and spectrum efficiency that can be used

[0066]

[0067] Calculate the generalized signal-to-noise ratio (GSNR) of all optical channels whose transmission capacity is not less than the service bandwidth requirement. link , GSNR is preferred link The highest optical channel serves as the new virtual link.

[0068] The generalized signal-to-noise ratio of each candidate optical channel is calculated as follows:

[0069]

[0070] Among them, GSNR lightpath Indicates the generalized signal-to-noise ratio (in dB) of each candidate optical channel, GSNR l WC represents the generalized signal-to-noise ratio of the lth link through which the optical channel L passes. penalty The wavelength converter used in this embodiment is a tunable type. The signal-to-noise ratio loss caused by each conversion is WC. penalty =0.2dB.

[0071] The calculation method for the generalized signal-to-noise ratio of the link through which the optical channel with a transmission capacity not less than the service bandwidth requirement is:

[0072]

[0073] The generalized signal-to-noise ratio of the lth link through which the optical channel L passes is calculated as follows:

[0074]

[0075] Among them, f i is the center frequency of the ith channel, P i is the channel transmit power, P ASE (f i ) is the spontaneous emission noise power accumulated by the optical signal on the lth link, P NLI (f i ) is the nonlinear interference power accumulated by the optical signal on the lth link.

[0076] The spontaneous emission noise power accumulated by the optical signal on the lth link is calculated as:

[0077]

[0078] Among them, F(f i ) represents the noise coefficient of the i-th channel, h represents the Planck constant, B i represents the bandwidth of the i-th channel, G post Represents the gain of the post-amplifier, G eff,m (f i ) represents the gain of the mth deployed line amplifier or preamplifier, N s Indicates the number of zoom spans.

[0079] The nonlinear interference power accumulated by the optical signal on the lth link is calculated as:

[0080] PNLI (f i )=B i ·G NLI (f i ),

[0081] Among them, B i represents the bandwidth of the i-th channel, G NLI (f i ) represents the power spectral density (PSD) of the nonlinear interference of the i-th channel.

[0082] The power spectral density of nonlinear interference in the i-th channel is calculated as:

[0083]

[0084] Where γ represents the fiber nonlinear coefficient (unit: 1 / (W·km)), N s Indicates the number of magnified spans, G Tx (f i ) represents the power spectrum density of the i-th channel transmission power, ρ(z,f) is the normalized amplitude profile function, d represents the length of the amplification span, Φ(f1,f2,f i,z )=-4π 2 (f1-f i )(f2-f i )[β2+πβ3(f1+f2)]z, β2 represents the second-order dispersion coefficient (group velocity dispersion), and β3 represents the third-order dispersion coefficient.

[0085] The normalized amplitude profile function is expressed as:

[0086]

[0087] Where g(ξ,f) is a function of the fiber loss and stimulated Raman scattering effect with respect to the fiber spatial coordinate ξ and frequency f. ξ is a distance variable and needs to be definite integrated.

[0088] Step 5: Select the highest-order modulation format available based on the new virtual link, configure the new service through the new virtual link, and update the remaining capacity on the link to complete the allocation. Then proceed to step 6.

[0089] Step 6: Continue to obtain the next new service and use the method in steps 1 to 5 to allocate the route and wavelength to the next new service until all service requests are processed.

[0090] The present invention also discloses a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the process of routing and wavelength allocation is realized in combination with the signal-to-noise ratio damage caused by the introduction of a wavelength converter.

[0091] Inter-band wavelength conversion technology allows wavelengths to be converted to corresponding positions in different bands based on the pump wavelength. The all-optical wavelength converter can perform wavelength conversion directly in the optical domain without the need for optical-electrical-optical (O / E / O) conversion. This process plays an important role in improving the utilization of network resources and reducing service blocking rates. Therefore, the present invention configures wavelength converters at a certain ratio on the ports so that some ports support inter-band conversion. Compared with the existing architecture, the present invention significantly reduces the number of wavelength converters and wavelength selection switch ports required when all wavelength converters are configured, effectively reducing costs while maintaining a low blocking probability and improving the scalability of the optical switching architecture. At the same time, by combining the signal-to-noise ratio damage caused by the introduction of wavelength converters for routing and wavelength allocation, the signal transmission quality of the optical switching architecture is improved.

[0092] To further demonstrate the beneficial effects of the present invention, simulation experiments were conducted using the present invention in this embodiment. The architecture parameters and related test parameters in the present invention are as follows: A COST239 network was used as the test network. The S-band, C-band, and L-band each had 32 channels. Four modulation formats were used: DP-QPSK, DP-8QAM, DP-16QAM, and DP-32QAM. Inter-band wavelength conversion was achieved using an all-optical wavelength converter. The ratio of ports configured with a wavelength converter to ports not configured with a wavelength converter was 1:1.

[0093] Under given routing and wavelength assignment conditions, the generalized signal-to-noise ratio (GSNR) of each optical channel was estimated, taking into account the performance impacts of spontaneous emission (ASE), nonlinear interference (NLI), stimulated Raman scattering (SRS), and wavelength conversion. The evaluation was conducted in the C+L+S bands, each with a bandwidth of 4.8 THz. These bands are divided into 32 channels on a 150 GHz WDM grid, each transmitting at a symbol rate of 128 GBaud.

[0094] The node structure adopts colorless, directionless (CD) add / drop configuration, and the ratio of the number of add / drop ports to the number of line-side ports is set to 0.5. The device cost data is based on the paper "JF Ramos, L. Cancela, and J. Rebola, “Influence of the ROADM architecture on the cost-per-bit in C+L+S multi-band optical networks”, in 2023 23rd International Conference on Transparent Optical Networks (ICTON), IEEE, 2023, pp. 1–4. DOI: 10.1109 / ICTON59386.2023.10207552, and normalized to the cost of a C-band erbium-doped fiber amplifier (EDFA). The specific values ​​are shown in Table 2. The cost of L-band components is assumed to be 20% higher than that of C-band components. The cost of S-band components is represented by a factor α, which ranges from 1.2 to 1.5. The cost of the all-optical wavelength converter (AO-WC) is controlled by a factor β, which ranges from 0.5 to 2. Assuming that the cost of S-band components is 20% higher than that of C-band components, the parameters are set to α = 1.2 and β = 2 in the experiment.

[0095] Table 2 Relative equipment cost table

[0096]

[0097] When using the routing and wavelength allocation method of the present invention, each optical channel can carry multiple sub-wavelength-level services, provided that the source node and destination node of the service are exactly the same as the source node and destination node of the optical channel. Service splitting is not allowed, that is, each service must use only a single optical channel. Assume that four modulation formats are used: DP-QPSK, DP-8QAM, DP-16QAM and DP-32QAM, and the corresponding channel capacities are 400Gb / s, 600Gb / s, 800Gb / s and 1000Gb / s respectively. The simulation is carried out under dynamic service scenarios, and a QoT system margin of 1.0dB is reserved for each optical channel to ensure the correct operation of the system.

[0098] In such Figure 6 The simulation experiment was conducted on the COST 239 topology shown in Figure 1, which has 11 nodes and 26 links. Each pair of adjacent nodes is connected by four pairs of optical fibers. The simulation scenario is a dynamic service configuration, where the arrival of services between each pair of nodes follows a Poisson distribution with an arrival rate of λ. The duration of each service follows an exponential distribution with a mean of 1 / μ = 1.0. The traffic load ρ (in Erlang) is defined as ρ = λ / μ = λ. A total of 10 simulations were performed. 6 business requests to evaluate blocking performance.

[0099] Use separately Figure 1Architecture, Figure 2 The architecture and the present invention are simulated, and the overall cost of the three architectures in the entire network is shown in Table 3.

[0100] Table 3. Overall cost of different architectures in the entire network

[0101] Conventional WSBS The present invention Cost 32765.44 120687.04 67992.64

[0102] In Table 3, Conventional is Figure 1 The architecture shown, WSBS is Figure 2 The conventional architecture has the lowest cost, WSBS has the highest, and the present invention falls somewhere in between. Notably, the present invention's total cost is 43.66% lower than WSBS. This significant cost advantage is primarily due to the present invention reducing the number of wavelength converters by half, significantly lowering the overall network construction cost. Furthermore, the present invention also reduces the number of WSS ports required, further improving cost-effectiveness. Even assuming that S-band and L-band devices are 20% more expensive than C-band devices, the present invention still maintains a significant cost advantage.

[0103] The blocking performance comparison of the three architectures in the COST239 network is shown in the figure below. Figure 7 As shown. Compared with the conventional method, the present invention performs better in blocking performance. Although the present invention is very close to WSBS in blocking performance, the present invention has advantages in terms of cost and is more advantageous in the large-scale expansion of optical switching architecture. In addition, since the ports without wavelength converters in the present invention do not need to perform wavelength conversion, the signal damage caused by the conversion is avoided, and thus higher-order modulation formats can be supported, thereby establishing large-capacity optical channels. For ports equipped with wavelength converters, spectrum resources can be fully utilized to create more optical channels, thereby improving the performance of the overall network.

[0104] As the traffic load between each pair of nodes increases, the blocking probability of all architectures increases. The present invention consistently matches WSBS in blocking performance, yet at a lower cost. This difference stems from the operating mechanism of the WSBS architecture: S-band and L-band optical signals must first be converted to the C-band before they can be exchanged via the C-band WSS; at the signal output stage, they must be converted back to the S / L-band. Therefore, a single optical path may undergo multiple wavelength conversions, significantly reducing its GSNR. In contrast, the present invention integrates two types of ports: those with and those without wavelength conversion capabilities. While this design sacrifices switching flexibility to some extent, the use of ports without conversion capabilities effectively avoids unnecessary wavelength conversions, thereby maintaining a higher GSNR. This advantage enables the optical path to support higher-order modulation formats, further increasing the transmission capacity of the optical channel.

[0105] Under the condition that the traffic load of each pair of nodes is 295 Erlang, as the ratio of wavelength conversion ports changes, the trend of network cost and blocking probability is as follows: Figure 8 As shown. The conversion ratio is defined as p = t / T, where t represents the number of ports with wavelength conversion capabilities and T is the total number of ports. When p = 0%, the architecture is equivalent to the traditional Conventional architecture; when p = 100%, it is equivalent to WSBS. As p increases, the number of required wavelength converters and the number of WSS ports also increase, resulting in an increase in the overall network cost. Figure 8 It can be seen that the blocking probability shows a downward trend in the initial stage of p increase, but begins to rise after exceeding a certain critical point. This is because when p is small, only a small number of light paths pass through the conversion port, and the impact of GSNR damage on network performance is not obvious. At the same time, the flexibility of network resource allocation is improved. When p is large, a large number of light paths need to pass through multiple wavelength converters, resulting in a significant decrease in GSNR, which in turn causes network performance to deteriorate. By reasonably balancing the ratio of ports with and without wavelength conversion functions, the blocking probability can be effectively reduced at a lower cost, achieving the optimal trade-off between performance and cost. When the setting ratio of wavelength converter ports is 50% (that is, the ratio of the number of configured and unconfigured wavelength converter ports is 1:1), the blocking probability is the lowest and the blocking performance is optimal.

[0106] It can be seen from the simulation experimental data that compared with Conventional, the present invention has a lower blocking probability; compared with WSBS, the blocking probability of the present invention is comparable, but the present invention has a lower cost and can overcome the limitations of WSBS when it is expanded on a large scale, thus proving the beneficial effects of the present invention.

[0107] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0108] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0109] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0110] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0111] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A multi-band optical switching architecture supporting wavelength conversion on some ports, characterized in that: include: The ports configured with wavelength converters include a demultiplexer or multiplexer, optical amplifiers operating in different wavelength bands, a wavelength converter, and a wavelength selective switch operating in the C-band. When an optical signal enters, it is routed sequentially through the demultiplexer, optical amplifiers operating in different wavelength bands, a wavelength converter, and a wavelength selective switch operating in the C-band. When an optical signal is output, it is sequentially routed through the wavelength converter, optical amplifiers operating in different wavelength bands, and the multiplexer to the optical fiber. Ports without wavelength converters include demultiplexers or multiplexers, optical amplifiers operating in different wavelength bands, and wavelength selective switches operating in different wavelength bands. When an optical signal enters, it is routed sequentially through the demultiplexer, optical amplifiers operating in different wavelength bands, and wavelength selective switches operating in different wavelength bands. When an optical signal is output, it is output to the optical fiber through optical amplifiers and multiplexers operating in different wavelength bands. The network controller performs routing and wavelength allocation in combination with the signal-to-noise ratio impairment caused by the introduction of wavelength converters.

2. The multi-band optical switching architecture supporting wavelength conversion at some ports according to claim 1, characterized in that: The routing is achieved sequentially through a demultiplexer, an optical amplifier operating in different wavelength bands, a wavelength converter, and a wavelength selective switch operating in the C band. Specifically, the wavelengths of different wavelength bands are separated by the demultiplexer, and the optical signals of each separated wavelength band are compensated for loss by the optical amplifier of the corresponding wavelength band. The optical signals of the S band and the L band are converted into optical signals of the C band by the wavelength converter, and all wavelengths of the C band are routed by the wavelength selective switch operating in the C band. The optical signal is sequentially output to the optical fiber through a wavelength converter, an optical amplifier operating in different wavelength bands, and a multiplexer. Specifically, the optical signal is converted into an S-band optical signal or an L-band optical signal by the wavelength converter, the optical signal after the wavelength conversion is compensated for loss by an optical amplifier of the corresponding wavelength band, and the compensated optical signal is multiplexed into all wavelengths by the multiplexer and output to the optical fiber; The routing is achieved in sequence through a demultiplexer, an optical amplifier operating in different wavelength bands, and a wavelength selective switch operating in different wavelength bands. Specifically, the wavelengths of different wavelength bands are separated by the demultiplexer, and the optical signals of each separated wavelength band are compensated for loss by the optical amplifier of the corresponding wavelength band. The wavelengths of different wavelength bands are routed by the wavelength selective switch operating in different wavelength bands. The optical amplifiers and multiplexers operating in different wavelength bands are used to output the optical signals to the optical fiber. Specifically, the optical amplifiers in the corresponding wavelength bands are used to compensate for the loss, and the compensated optical signals are multiplexed into all wavelengths through the multiplexer and output to the optical fiber.

3. The multi-band optical switching architecture supporting wavelength conversion at some ports according to claim 1, wherein: The routing and wavelength allocation are performed in combination with the signal-to-noise ratio loss caused by the introduction of the wavelength converter. The routing and wavelength allocation process is specifically as follows: Acquire the new service that has arrived and search for the virtual link between the source and destination nodes of the new service. Determine whether the virtual link exists and has sufficient capacity. If so, configure the new service through the virtual link and update the remaining capacity on the link. Otherwise, perform the steps of finding K shortest paths for the new service. Find K shortest paths for the new service. Under the condition of wavelength continuity, find available optical fibers for each link along the path and check the availability of transmitters, receivers, and nodes. If available, add the optical path to the candidate optical channel. The optical path is an end-to-end optical signal transmission channel established along a wavelength on each intermediate link in the path from the source node to the destination node. Determine whether a candidate optical channel exists. If not, perform the step of finding K shortest paths for the new service again. If yes, perform the step of selecting an optical channel based on bandwidth requirements and signal-to-noise ratio degradation caused by the introduction of wavelength converters. Again, K shortest paths are found for the new service. If wavelength continuity is not met, a recursive and backtracking algorithm is used to find available fiber and idle wavelengths for each link on the path. The availability of transmitters, receivers, and nodes is checked. If available, the optical path is added to the candidate optical channel. A check is again made to determine whether a candidate optical channel exists. If not, the new service is blocked. If yes, the optical channel selection step is performed based on bandwidth requirements and the signal-to-noise ratio degradation caused by the introduction of wavelength converters. Select an optical channel based on bandwidth requirements and signal-to-noise ratio degradation caused by the introduction of a wavelength converter, and use the selected optical channel as a new virtual link; if all candidate optical channels cannot be used as the new virtual link, determine whether the step of searching for K shortest paths for the new service has been performed again; if not, perform the step of searching for K shortest paths for the new service again; otherwise, block the new service; The highest-order modulation format available is selected based on the new virtual link, new services are configured through the new virtual link, and the remaining capacity on the link is updated.

4. The multi-band optical switching architecture supporting wavelength conversion at some ports according to claim 3, wherein: The optical channel is selected based on bandwidth requirements and signal-to-noise ratio degradation caused by the introduction of a wavelength converter, specifically: The generalized signal-to-noise ratio (SNR) of each candidate optical channel is calculated by comprehensively considering the signal-to-noise ratio impairment caused by wavelength converters, the spontaneous emission noise introduced by optical amplifiers, nonlinear interference during fiber transmission, and stimulated Raman scattering. Based on the correspondence between the generalized SNR and modulation format of each candidate optical channel, the highest-order modulation format that can be used for the optical channel is determined, thereby deriving the maximum transmission capacity of the optical channel. An optical channel with a transmission capacity not less than the service bandwidth requirement and a link with the highest generalized signal-to-noise ratio is selected as a new virtual link.

5. The multi-band optical switching architecture supporting wavelength conversion at some ports according to claim 4, characterized in that: The generalized signal-to-noise ratio of each candidate optical channel is calculated as follows: Among them, GSNR lightpath Represents the generalized signal-to-noise ratio of the optical channel, GSNR l WC represents the generalized signal-to-noise ratio of the lth link through which the optical channel L passes. penalty represents the signal-to-noise ratio loss introduced by a single wavelength converter, k represents the number of wavelength converters configured on the optical channel, and L represents the set of all links on the optical channel; The transmission capacity is not less than the generalized signal-to-noise ratio of the link through which the optical channel of the service bandwidth requirement passes, and the calculation method is:

6. The multi-band optical switching architecture supporting wavelength conversion at some ports according to claim 5, characterized in that: The generalized signal-to-noise ratio of the lth link through which the optical channel L passes is calculated as follows: Among them, f i is the center frequency of the ith channel, P i is the channel transmit power, P ASE (f i ) is the spontaneous emission noise power accumulated by the optical signal on the lth link, P NLI (f i ) is the nonlinear interference power accumulated by the optical signal on the lth link.

7. The multi-band optical switching architecture supporting wavelength conversion at some ports according to claim 6, characterized in that: The spontaneous emission noise power accumulated by the optical signal on the lth link is calculated as follows: Among them, F(f i ) represents the noise coefficient of the i-th channel, h represents the Planck constant, B i represents the bandwidth of the i-th channel, G post represents the gain of the post-amplifier, represents the gain of the mth deployed line amplifier or preamplifier, N s Indicates the number of zoom spans.

8. The multi-band optical switching architecture supporting wavelength conversion at some ports according to claim 6, wherein: The nonlinear interference power accumulated by the optical signal on the lth link is calculated as follows: P NLI (f i )=B i ·G NLI (f i ), Among them, B i represents the bandwidth of the i-th channel, G NLI (f i ) represents the power spectral density of the nonlinear interference of the i-th channel.

9. The multi-band optical switching architecture supporting wavelength conversion at some ports according to claim 8, characterized in that: The power spectrum density of the nonlinear interference of the i-th channel is calculated as follows: Where γ represents the fiber nonlinear coefficient, N s Indicates the number of magnified spans, G Tx (f i ) represents the power spectrum density of the i-th channel transmission power, f1+f2-f i represents the new channel generated by the four-wave mixing intermodulation phenomenon between the first channel, the second channel and the i-th channel, ρ(z,f) is the normalized amplitude profile function, d is the length of the amplification span, Φ(f1,f2,f i,z )=-4π 2 (f1-f i )(f2-f i )[β2+πβ3(f1+f2)]z, β2 represents the second-order dispersion coefficient, and β3 represents the third-order dispersion coefficient.

10. The multi-band optical switching architecture supporting wavelength conversion at some ports according to claim 9, characterized in that: The normalized amplitude profile function is expressed as: where g(ξ,f) is a function of the fiber's loss and stimulated Raman scattering effect with respect to the fiber's spatial coordinate ξ and frequency f.

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