A digital subcarrier multiplexing based multi-passive optical network system and a dynamic bandwidth allocation method thereof

Abstract

The application discloses a kind of based on digital subcarrier multiplexing multi-passive optical network system and its dynamic bandwidth allocation method, the scheme is divided into multiple independent adjustable subcarrier channels by digital subcarrier multiplexing technology on electric domain, and the number of subcarriers is dynamically adjusted and distributed to each PON, so as to realize the differentiated bandwidth allocation between different PONs, satisfy the bandwidth demand between multi-PON changes with region and time.The steps of dynamic bandwidth allocation method are: step S1: predict bandwidth demand, calculate demand satisfaction rate and determine priority for each ONU (Optical Network Unit) in multi-PON;Step S2: count the bandwidth demand of different priority of each PON;Step S3: calculate and dynamically allocate a certain number of subcarriers for each PON;Step S4: dynamically allocate bandwidth to each ONU in PON according to priority;Step S5: activate / close neighbor subcarrier;Step S6: global subcarrier reconfiguration is carried out.

Description

Technical Field

[0001] This invention relates to the field of resource allocation in optical fiber access communication technology, specifically to a multi-passive optical network (PON) system based on digital subcarrier multiplexing (DSCM) and its dynamic bandwidth allocation method, which is suitable for efficient spectrum resource management in multi-service convergence scenarios. Background Technology

[0002] With the development of multi-service convergence trends such as 5G backhaul, enterprise access, and home broadband, the data traffic carried by optical networks is growing at an unprecedented rate. Users' demands for network resources are no longer limited to simple bandwidth expansion, but rather place greater emphasis on flexibility, timeliness, and adaptability. Traditional PON systems use fixed wavelength configurations for each PON, which is increasingly showing its inadequacy in terms of wavelength and bandwidth sharing capabilities. It struggles to cope with the diverse, dynamic, and sudden dynamic bandwidth demands between different PONs due to time and regional differences, resulting in low resource utilization. To address this issue, multi-PON system technology has gained increasing attention. A multi-PON system refers to the simultaneous deployment of multiple PON networks within the same optical fiber infrastructure. It typically introduces multiple wavelengths for shared transmission among multiple PONs, improving the overall capacity and resource utilization efficiency of the PON network, and meeting the diverse, high-bandwidth service demands of the future.

[0003] In existing PON technologies, the static wavelength and bandwidth allocation strategies between PONs cannot respond to traffic fluctuations in real time, leading to resource waste or shortages. This is especially problematic under medium-to-high load scenarios, where latency deteriorates significantly, failing to meet the QoS requirements of high-priority services and the "on-demand allocation, real-time scheduling" requirements of next-generation optical access networks. Therefore, more efficient and refined resource management methods are urgently needed. High-speed multi-PON technology based on Electrical Domain Digital Subcarrier Multiplexing (DSCM) using coherent optical transceivers is one such technology. DSCM technology carries multiple digital subcarriers (SCs) on a single optical carrier, each capable of carrying data independently, thus achieving refined management and efficient utilization of spectrum resources. This flexible subcarrier configuration supports dynamic on-demand bandwidth allocation, enabling the network to respond quickly to traffic fluctuations and avoiding resource waste or shortages in traditional network architectures. Flexible and efficient bandwidth allocation through spectrum management significantly improves channel utilization and reduces resource waste. Furthermore, by employing DSCM technology, multi-PON systems only require a single wavelength, resulting in fewer lasers compared to traditional solutions using multiple wavelengths and laser arrays. Additionally, no additional wavelength switching and routing equipment (such as AWG) is needed. This effectively reduces the complexity of network equipment and overall cost, further enhancing the network's economy and practicality. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-PON (Passive Optical Network) system architecture based on Digital Subcarrier Multiplexing (DSCM) technology and its dynamic bandwidth allocation method, so as to achieve flexible control and precise allocation of network resources and comprehensively improve the network's adaptability in multi-service convergence scenarios.

[0005] To achieve the above objectives, this invention utilizes digital subcarrier multiplexing technology to enable each subcarrier channel to carry data independently. Based on this, subcarriers are dynamically allocated to each PON, and bandwidth is dynamically allocated to each ONU within the PON, thereby maximizing network resource utilization and minimizing latency. Furthermore, when ONU bandwidth allocation fails, adjacent subcarrier resources are preferentially activated / deactivated to reduce the spectrum reconfiguration costs and latency caused by frequent subcarrier migrations. Specifically, the invention includes the following steps:

[0006] Step S1: Predict bandwidth requirements for each ONU in a multi-PON network, calculate the requirement fulfillment rate, and determine priorities;

[0007] Step S2: Calculate the bandwidth requirements of each PON;

[0008] Step S3: Calculate and dynamically allocate a certain number of subcarriers to each PON;

[0009] Step S4: Dynamically allocate bandwidth to each ONU within the PON according to priority;

[0010] Step S5: Activate / deactivate neighbor subcarriers;

[0011] Step S6: Perform global subcarrier reconfiguration;

[0012] In addition, this allocation method uses two independent cycles:

[0013] Long period (10 minutes): During this period, the number of subcarriers is dynamically allocated to each PON according to the service requirements.

[0014] Short period (2 milliseconds): Within this period, bandwidth resources are rapidly and dynamically allocated among ONUs within each PON. When a service change within a PON exceeds a predetermined limit, a reallocation of subcarriers is triggered.

[0015] A multi-PON system architecture based on digital subcarrier multiplexing divides the available bandwidth of the PON system into multiple subcarriers and flexibly allocates them among multiple PONs via P2MP (point-to-multipoint). Each subcarrier can be processed independently of other subcarriers, including modulation, management, aggregation, etc., and routed to different destinations. It can flexibly allocate subcarriers among different PONs according to different service scenarios, and flexibly allocate bandwidth among different ONUs (Optical Network Units) within the same PON, improving fiber resource utilization and simplifying access network planning and upgrades.

[0016] (1) ONU bandwidth demand prediction, dynamic priority determination and subcarrier scheduling (step S1): For the first Each optical network unit (ONU) defines the demand fulfillment rate. Preset threshold (like =0.8), if < It is marked as a high-priority ONU, otherwise it is a low-priority ONU. The definition is as follows:

[0017]

[0018] in, express The bandwidth actually allocated in the previous cycle for Demand forecasts from the previous cycle.

[0019] Load forecasting: Collect bandwidth demand data from ONUs over several previous time periods, and predict the bandwidth demand for the next time period using a moving average algorithm. :

[0020]

[0021] Where W is the length of the moving average window, that is, the average calculation is performed by selecting data from the past W periods; For the i-th ONU in the past... Actual bandwidth requirements within a period It is the predicted bandwidth requirement of the i-th ONU in the next cycle;

[0022] Subcarrier scheduling: Prioritize allocating subcarriers to high-priority ONUs. When resources are insufficient, implement adjacent subcarrier release, service migration, or global reconfiguration strategies.

[0023] This step dynamically adjusts subcarrier resources to ensure that high-priority services receive the necessary bandwidth, preventing service quality degradation due to insufficient bandwidth. Simultaneously, it releases subcarriers or migrates services when resources are scarce, making network resource allocation more flexible and efficient. This avoids the resource waste associated with traditional static configurations and improves overall spectrum utilization and network response speed.

[0024] (2) Calculate the bandwidth requirements of each PON (step S2)

[0025] Calculate the total bandwidth requirements of high-priority ONUs for each PON separately.

[0026]

[0027] Total bandwidth requirements of low-priority ONUs

[0028]

[0029] They are used to determine the overall bandwidth requirements for each PON.

[0030]

[0031] in This is a weighting coefficient used to control the degree of influence of low-priority demands on subcarrier allocation. For example, let... When the setting is larger Value (e.g.) This will reserve more subcarrier resources, thereby reducing the frequency of subsequent PON subcarrier changes.

[0032] The advantage of this step is that it reduces the frequency of subsequent subcarrier adjustments and resource reconfigurations between PONs. Frequent subcarrier changes can lead to network service interruptions or performance instability. By reserving certain resources in advance with a larger weighting coefficient, the frequency of system reconfiguration can be significantly reduced, thereby improving network stability and service continuity. This is especially suitable for environments where frequent spectrum resource adjustments are costly, maintaining stable system operation and reducing maintenance costs.

[0033] (3) Calculate and dynamically allocate the number of subcarriers for each PON (step S3)

[0034] Subcarrier allocation is dynamically adjusted based on the bandwidth requirements of each PON: the number of subcarriers for each PON is dynamically adjusted according to its bandwidth requirements. Assume the system has N subcarriers and n PONs, with each PON receiving N subcarriers. j The calculation is as follows:

[0035]

[0036] in, for Total bandwidth requirements.

[0037] The number of subcarriers N in the last PON n The following formula will be used to adjust and ensure that all subcarrier resources are allocated:

[0038]

[0039] The specific advantages of this step are as follows: First, by utilizing the proportional relationship of bandwidth demand, resources are allocated fairly and reasonably to each PON, efficiently meeting the differentiated bandwidth needs of users and avoiding situations where resources are allocated too much or too little. Second, the number of subcarriers for the last PON in the formula is determined by the difference in the number of subcarriers for all preceding PONs, thus ensuring the full utilization of subcarrier resources and maximizing the overall utilization and management efficiency of spectrum resources. This flexible configuration method significantly enhances the network's adaptability to load changes while reducing the possibility of frequent resource reconfiguration, thereby improving the stability and reliability of network operation.

[0040] (4) Dynamically allocate bandwidth to each ONU within the PON according to priority (step S4)

[0041] After differentiating high-priority and low-priority ONUs based on demand satisfaction rate, bandwidth is allocated to high-priority ONUs first, followed by low-priority ONUs. When allocating bandwidth to ONUs, the current... Unmet needs r i (Initially set to d) i In the subcarrier set, find the subcarrier k with remaining capacity and perform a bandwidth allocation 𝛿=min(𝑟 𝑖 (Remaining capacity). Update r i ←r i - The available capacity of 𝛿 and subcarriers; if r i If the value is still greater than 0, then the next subcarrier will be allocated. If the bandwidth allocated to a high-priority ONU is insufficient, bandwidth can be released from neighboring low-utilization subcarriers to meet the requirement.

[0042] (5) Activate / deactivate adjacent subcarriers (step S5):

[0043] When an ONU needs more bandwidth than the available bandwidth of all subcarriers allocated to that ONU, low-utilization subcarriers are first released from its neighboring ONUs and then allocated to the ONU with high demand.

[0044] Subcarrier utilization and release strategy: Let u k The utilization rate of subcarrier k is expressed as follows:

[0045]

[0046] Where b i，k It is assigned to ONU i The bandwidth on subcarrier k, C k This represents the maximum capacity of the subcarrier. If u k If the value is lower than the reference value U, the subcarrier is considered to be partially or fully released to other ONUs that need it, and the original ONU services on the subcarrier will be migrated during the release. If the adjacent subcarrier is successfully released, the process returns to step S4 to continue allocation; if the release fails, cross-PON subcarrier sharing is performed.

[0047] ① Shared subcarrier resources among neighboring ONUs within the same PON

[0048] First, the subcarrier resource status is checked within a single PON. When the bandwidth requirement allocated to a certain ONU cannot be directly met, the algorithm will look for subcarriers with lower utilization among the neighboring ONUs within that PON, release some or all of the resources, and allocate them to ONUs with higher requirements to meet the bandwidth needs of high-priority ONUs.

[0049] ② Resource sharing of neighboring subcarriers across PON

[0050] If the bandwidth requirements of the ONU cannot be met even after releasing resources within the same PON, a cross-PON subcarrier resource sharing mechanism is further considered. The algorithm dynamically uses underutilized subcarrier resources within neighboring PONs, temporarily releasing and reallocating them to PONs with greater bandwidth requirements to optimize the overall network resource utilization efficiency.

[0051] ③ ONU service migration

[0052] The process involves identifying neighboring low-priority ONUs and checking if their subcarriers can be migrated entirely to other subcarriers or further locations, freeing up adjacent subcarrier resources occupied by the ONU for use by the current high-priority ONU. Subcarriers with the lowest total real-time bandwidth demand of ONUs or subcarriers with zero ONUs are designated as idle subcarriers, and ONUs on these idle subcarriers are migrated to other designated subcarriers. During migration, ONUs with lower real-time bandwidth demands are prioritized until the bandwidth utilization of the target subcarrier is no less than 50% of its capacity. The target subcarrier should have sufficient remaining capacity to support the real-time bandwidth demands of the migrated ONU. This service migration ensures that high-priority ONUs receive more ample and timely resource supply, significantly improving network quality of service (QoS) assurance capabilities. Furthermore, by selecting subcarriers with the lowest bandwidth demand or completely idle subcarriers as migration sources, severe interference or interruption to other services is avoided, and the load on the target subcarrier during migration does not exceed a reasonable threshold (50%). This improves the success rate of migration operations and reduces network performance fluctuations and latency issues caused by frequent migrations.

[0053] The advantage of the adjacent subcarrier activation and deactivation strategy lies primarily in its ability to aggregate subcarriers into continuous subcarrier frequency bands. This facilitates the use of coherent detection at the receiver to detect information from that subcarrier frequency band in a single optical transmission. For example, if the receiver sets the local oscillator laser frequency to [missing information]... It passes through and carries Signal optical carrier in range subcarrier frequency band Beat frequency can detect in one go The subcarrier signals are dynamically evaluated. Subcarriers below a certain threshold can be released in a timely manner, allowing these resources to be reallocated to ONUs with higher bandwidth demands. This enables rapid response to changes in bandwidth requirements, improving the flexibility and responsiveness of network resources. Furthermore, neighbor ONU resource sharing enables local bandwidth optimization within a single PON and flexible scheduling of idle resources across PONs. This reduces the risk of service quality degradation and interruptions due to insufficient bandwidth, and decreases the cost and complexity of network resource reallocation. This step also optimizes overall network performance, reduces unnecessary service migration and subcarrier reconfiguration operations, and improves the continuity of network services and the stability of user experience.

[0054] (6) Global Subcarrier Reconfiguration (Step S6): Find the subcarrier with the lowest utilization rate from the global subcarriers and reconfigure it or preempt the bandwidth of low-priority ONUs to reduce the overhead caused by frequent global changes. After completing the reconfiguration, try to allocate bandwidth to the current ONU. If it still cannot be satisfied, wait for the next cycle to allocate bandwidth. If the global reconfiguration still fails, it means that the network resources have reached a bottleneck. Abandon more allocations in this cycle and wait for the next cycle to schedule.

[0055] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the aforementioned passive optical network system based on digital subcarrier multiplexing and its dynamic bandwidth allocation method.

[0056] A computer-readable storage medium storing computer instructions that, when executed by a processor, implement the aforementioned passive optical network system based on digital subcarrier multiplexing and its dynamic bandwidth allocation method.

[0057] Compared with the prior art, the advantages of the present invention are as follows: (1) Strong network expansion capability. It can increase the number of PONs and optical network units (ONUs) by adding subcarriers. When the number of PONs or users increases, network operators do not need to carry out large-scale and complex modifications to the network architecture. They can access more PONs or users simply by flexibly adjusting the subcarrier resources. Compared with the traditional passive optical network, which requires adding optical transceivers and wavelength routing devices to add PONs and may face problems such as fiber optic resource shortage and splitting ratio limitation when adding ONUs, the digital subcarrier-based scheme provides a convenient way to expand network capacity; (2) ONUs allocated with different subcarriers do not need to be synchronized on the uplink, which simplifies the system design and operation mechanism. In the traditional passive optical network, all ONUs need to achieve time synchronization and ranging with the OLT to ensure that the signals sent by different ONUs do not conflict on the uplink. The implementation process is cumbersome and easily affected by environmental factors. However, in the passive optical network based on digital subcarrier multiplexing, when each ONU uses an independent subcarrier to transmit data, the signal conflict problem is fundamentally avoided without complex synchronization operations. This reduces the complexity of the system, reduces equipment costs and maintenance difficulty; (3) Based on the distance between the PON (or ONU) and the OLT, the subcarriers allocated to the PON (or ONU) can be adaptively modulated according to distance. When the distance is close, high-order modulation is used to improve the spectral efficiency of each subcarrier, and low-order modulation is used to improve transmission performance when the distance is far. This is something that traditional PON networks cannot achieve; (4) The proposed dynamic bandwidth allocation scheme prioritizes the allocation of resources to nodes with high demand through demand prediction and priority dynamic judgment mechanism, effectively solving the problem of insufficient priority guarantee in traditional static allocation. It can significantly improve the subcarrier utilization rate in medium and high load scenarios. At the same time, in high load scenarios, DSCM-DA can significantly reduce network latency compared to static allocation algorithms and has strong adaptability to load changes; (5) Compared with the scheme of implementing multiple PON systems with multiple wavelengths and laser arrays, this invention uses DSCM technology, so the multiple PON system only needs to use a single wavelength, requires fewer lasers and optical receivers, and does not require additional wavelength switching and routing equipment. In summary, this invention has advantages in PON and ONU expansion, uplink synchronization simplification, spectrum utilization, transmission performance, priority-based quality of service, and device cost. It has great application potential and development prospects in building efficient, reliable, and scalable future access networks. Attached Figure Description

[0058] Figure 1 This is a diagram of a multi-PON system architecture based on digital subcarrier multiplexing.

[0059] Figure 2 This is a flowchart of the bandwidth allocation algorithm for a multi-PON system based on digital subcarrier multiplexing technology.

[0060] Figure 3 The graph shows the average subcarrier utilization for different numbers of subcarriers.

[0061] Figure 4 This is a comparison chart of average subcarrier utilization under different strategies.

[0062] Figure 5 The graph shows the trend of ONU service migration load and fixed allocation load under different normalized loads.

[0063] Figure 6 The graph shows the average network delay for different numbers of subcarriers.

[0064] Figure 7 This is a comparison chart of average network latency under different strategies.

[0065] Figure 8 A comparison chart of satisfaction factors under different business scenarios. Detailed Implementation

[0066] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. However, these embodiments are not intended to limit the present invention. Any similar structures or variations thereof that adopt the present invention should be included within the scope of protection of the present invention.

[0067] Example: Multi-PON system based on DSCM technology (e.g.) Figure 1 As shown, a P2MP pluggable transceiver is deployed at the OLT, which divides the total 400G bandwidth into 16 25Gb / s subcarriers. Each subcarrier can transmit user data independently. According to the bandwidth requirements of each PON, one subcarrier (25Gbps) is allocated to PON1, and 3 (75Gbps), 4 (100Gbps), and 8 (200Gbps) adjacent subcarriers are allocated to PON2, PON3, and PON4, respectively.

[0068] The flowchart of the dynamic bandwidth allocation algorithm for multi-PON systems using DSCM technology is as follows: Figure 2 As shown, it is divided into long-period multi-PON subcarrier scheduling and short-period ONU bandwidth allocation. Long-period multi-PON subcarrier scheduling performs the following operations:

[0069] Operation 1: Calculate the total bandwidth requirements of ONUs with different priorities in each PON.

[0070] Calculate the total bandwidth requirements of high-priority ONUs for each PON separately.

[0071]

[0072] Total bandwidth requirements of low-priority ONUs

[0073]

[0074] They are used to determine the overall bandwidth requirements for each PON.

[0075]

[0076] in This is a weighting coefficient used to control the degree of influence of low-priority demands on subcarrier allocation. For example, let... When the setting is larger value( When this is done, more subcarrier resources will be reserved, thereby reducing the frequency of subsequent PON subcarrier changes.

[0077] Operation 2: Calculate and dynamically adjust the number of subcarriers for each PON.

[0078] The number of subcarriers in each PON is dynamically adjusted based on its bandwidth requirements. Assume the system has N subcarriers and n PONs. for The total bandwidth requirement is then Number of subcarriers N j The calculation is as follows:

[0079]

[0080] The number of subcarriers N in the last PON n The following formula will be used to adjust and ensure that all subcarrier resources are allocated:

[0081]

[0082] In short-cycle ONU bandwidth allocation, for each ONU i Perform the following operations:

[0083] Operation 1: Collect historical demand data and predict the ONU bandwidth demand for the next cycle;

[0084] collect Bandwidth demand for previous periods is predicted using a moving average algorithm. Bandwidth requirements for the next time period :

[0085]

[0086] Where W is the length of the moving average window, that is, the average calculation is performed by selecting data from the past W periods; For ONU in the past The actual bandwidth requirement within each cycle.

[0087] Operation 2: Calculation Bandwidth demand fulfillment rate And determine priorities;

[0088] make The demand is Based on the allocated bandwidth of the previous time period With forecast demand Calculate the demand satisfaction rate of this ONU. .if ,mark If it is a high-priority ONU, then it is a low-priority ONU.

[0089] Operation 3: Allocate bandwidth to ONUs within each PON according to priority;

[0090] Within each PON, bandwidth is allocated based on ONU priority. First, the predicted bandwidth requirements of high-priority ONUs are met. If bandwidth resources are insufficient, low-utilization subcarriers of neighboring ONUs within the same PON are released (to migrate their services), and then bandwidth is allocated to that ONU. If bandwidth resources are still insufficient after releasing subcarriers within the same PON, then subcarrier allocation between different PONs is considered.

[0091] Operation 4: Release low-utilization subcarriers in neighboring ONUs within the same PON;

[0092] The subcarrier resource status is checked within the PON. When the bandwidth requirement of a certain ONU cannot be directly met, the less utilized subcarriers are searched among the neighboring ONUs within the PON, and some or all of the resources are released and allocated to ONUs with higher requirements to meet the bandwidth requirements of high-priority ONUs.

[0093] Operation 5: Sharing of neighboring subcarrier resources across PONs;

[0094] If the bandwidth requirements of the ONU cannot be met even after releasing resources within the same PON, a cross-PON subcarrier resource sharing mechanism is further considered. The algorithm dynamically uses underutilized subcarrier resources within neighboring PONs, temporarily releasing and reallocating them to PONs with greater bandwidth requirements to optimize the overall network resource utilization efficiency.

[0095] Operation 6: Global subcarrier reconfiguration;

[0096] If the above steps still cannot meet the current bandwidth requirements of the ONU, the algorithm will perform a broader subcarrier resource reconfiguration. Specifically, it will search for subcarrier resources globally, prioritizing the release of the least utilized subcarriers or preempting resources serving low-priority ONUs to meet the bandwidth needs of high-priority or high-demand ONUs.

[0097] To verify the effectiveness of the aforementioned DSCM technology PON system and its bandwidth allocation algorithm, simulation analysis was conducted using key performance indicators such as average subcarrier utilization, latency, and ONU migration load, and the results were compared with those of the traditional static allocation algorithm. To better simulate bursty service demands in the network, the bandwidth demand value of each ONU in each cycle was randomly generated using a Poisson distribution. The average value of the random numbers in the Poisson distribution was avg=1.5, and the range of random numbers was limited to 0-8 to control the fluctuation range of demand. The randomly generated integer values ​​were normalized and mapped to the actual bandwidth demand range, thus ensuring that the generated bandwidth demand possesses both bursty randomness and remains within the reasonable carrying capacity of network resources. Specific simulation parameter settings are as follows:

[0098] Table 1 Simulation Parameter Settings

[0099] Simulation parameters numerical values Number of subcarriers 4,8,16 Maximum transmission rate per subcarrier 25 Gbps Number of ONUs (per PON) 128 PON quantity 4 ONU Initial Bandwidth Requirements 0.1-6 Gbps Maximum polling cycle of the algorithm 2ms, 10min

[0100] like Figure 3 The figure shows the average subcarrier utilization for 4, 8, and 16 subcarriers. For 4 subcarriers, the utilization rate rises rapidly with increasing load, eventually approaching saturation. In contrast, the utilization rates for 8 and 16 subcarriers show a more gradual increase. At lower loads, the system can more effectively allocate bandwidth to more subcarriers, ensuring that the resources of each subcarrier are used efficiently. As the load increases, more subcarriers are activated, further improving the overall resource utilization. Increasing the number of subcarriers allows the system to effectively allocate resources even at lower loads, avoiding excessive bandwidth concentration and improving system flexibility and scalability.

[0101] With 16 subcarriers, the average subcarrier utilization under different strategies is as follows: Figure 4As shown, the DSCM-DA (Digital Subcarrier Multiplexing-Dynamic Allocation) curve rapidly increases to a high level under low load and tends to saturate; while static subcarrier allocation increases relatively slowly, gradually approaching saturation only under higher load. Under all normalized load conditions, the average subcarrier utilization of the DSCM-DA scheme is significantly higher than that of the static subcarrier allocation scheme. Under medium load (e.g., 0.4-0.8), DSCM-DA shows a significant advantage over static subcarrier allocation, indicating that DSCM-DA is more adaptable to load changes and has higher resource utilization efficiency. This is mainly because the DSCM-DA algorithm can dynamically adjust subcarriers, prioritizing the search for or reclamation of low-priority bandwidth resources in adjacent subcarriers during traffic bursts and making full use of remaining bandwidth for allocation, thus ultimately achieving a relatively ideal uplink bandwidth utilization.

[0102] Define the total data volume of all ONUs that migrate within the t-th period as the service migration load M(t) for that period, then:

[0103]

[0104] Among them, M i (t) represents the amount of business data that was migrated by the nth ONU in period t.

[0105] Average service migration load over all periods during simulation In the specific expression, where, This represents the total number of scheduling cycles.

[0106]

[0107] The changing trends of ONU service migration load and fixed allocation load under different load conditions are as follows: Figure 5 As shown, as network load gradually increases, network resource utilization tends to saturate. Some ONUs are unable to meet their needs within the fixed allocated resources, triggering service migration to better utilize adjacent subcarrier resources, thereby improving overall bandwidth utilization efficiency.

[0108] like Figure 6As shown, under the same three different subcarrier configurations, the average latency gradually increases with the increase of normalized load. At low loads, the latency differences among the three subcarrier configurations are small, indicating that the system has good responsiveness and resource allocation efficiency under low load conditions. With increasing load, the system latency increase with 16 subcarriers is relatively gradual, indicating that the system can effectively distribute the load using more subcarrier resources, thereby alleviating system congestion. However, the system latency with 4 subcarriers increases more rapidly, exhibiting a more significant delay problem. This is because when the number of subcarriers is small, system resources are relatively scarce. When the load increases, subcarrier resources are easily preempted, leading to bandwidth allocation bottlenecks and significantly increasing latency. Overall, increasing the number of subcarriers helps alleviate latency problems under high load conditions, but adding too many subcarriers may also lead to insufficient resource utilization. Therefore, a reasonable balance between resource allocation and latency control is needed under different conditions.

[0109] The average network latency performance of DSCM-DA and traditional static allocation algorithms under different network loads is as follows: Figure 7 As shown, with the gradual increase in network load, the network latency of traditional static allocation algorithms rises rapidly under high load, exhibiting a significant latency degradation trend. In contrast, the DSCM-DA proposed in this invention, due to its use of digital subcarrier multiplexing technology, can flexibly and dynamically adjust the allocation of subcarriers according to the actual needs of the network. It can cope with changes in bandwidth demand under high load conditions and better maintain the network's latency performance advantage even when the network load increases.

[0110] To more comprehensively reflect the overall rationality of bandwidth allocation and user experience, this bandwidth allocation algorithm introduces the average bandwidth demand satisfaction level. The bandwidth resource allocation is evaluated. The average bandwidth demand satisfaction rate is defined as the weighted average of the bandwidth demand satisfaction rates of each ONU:

[0111]

[0112] Where n is the total number of ONUs. This represents the weight corresponding to the i-th ONU, reflecting its business priority or importance. It also satisfies the weight normalization condition:

[0113]

[0114] This represents the bandwidth demand satisfaction rate of the i-th ONU, i.e., the ratio between the actual allocated bandwidth and the requested bandwidth:

[0115]

[0116] When the average bandwidth demand satisfaction rate is close to 1, it indicates that the overall bandwidth resource allocation of the system is ideal.

[0117] Simulation results of satisfaction factors under different business scenarios are as follows: Figure 8 As shown, in 5G backhaul scenarios, the average bandwidth demand satisfaction rate of traditional static allocation strategies is only around 0.62, reflecting the inadequacy of static strategies in handling rapidly changing service demands. In contrast, the average bandwidth demand satisfaction rate of the DSCM-DA strategy can remain around 0.98. This indicates that in service scenarios with high network performance and real-time requirements, the dynamic prediction and flexible scheduling capabilities of DSCM-DA can significantly improve network resource allocation efficiency and ensure stable and reliable bandwidth guarantees for high-priority services. In enterprise user scenarios, given the high bandwidth requirements of enterprise users, static bandwidth allocation methods are unable to detect fluctuations in high-demand service volumes such as video conferencing and cloud office, and cannot make dynamic and flexible resource allocations, resulting in an average bandwidth demand satisfaction rate of only 0.7. The DSCM-DA strategy, however, performs exceptionally well, with an average bandwidth demand satisfaction rate remaining above 0.9. This is mainly because the dynamic bandwidth allocation mechanism can predict and respond to fluctuations in enterprise users' bandwidth demands in a timely manner, achieving rapid resource response and effectively improving enterprise users' satisfaction with network service quality. In residential user scenarios, the average bandwidth requirement satisfaction rate of the traditional static subcarrier allocation strategy reached about 0.75, which has shown good service performance; while the average bandwidth requirement satisfaction rate of the DSCM-DA strategy was 0.92, which significantly improved the network experience of residential users. This shows that the DSCM-DA strategy can still effectively utilize idle resources and further improve the user experience in relatively stable business scenarios.

[0118] In summary, this invention presents a multi-passive optical network system based on digital subcarrier multiplexing and its dynamic bandwidth allocation method. By subdividing the spectrum of a single optical carrier into independently adjustable digital subcarriers, a point-to-multipoint (P2MP) architecture is constructed, addressing the problems of low spectrum utilization and insufficient flexibility in traditional optical networks. The accompanying algorithm prioritizes resources based on demand satisfaction rate, predicts load, and implements neighbor subcarrier resource sharing within the same PON and across PONs in adjacent subcarrier release strategies. This achieves efficient resource scheduling, improves spectrum utilization, reduces latency, and optimizes costs in multi-service convergence scenarios. Simulation results demonstrate that this scheme significantly outperforms traditional static allocation schemes in key indicators such as subcarrier utilization, average latency, and service satisfaction, providing an efficient and flexible solution for next-generation optical access networks.

[0119] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention or its equivalents are included in this invention.

Claims

1. A multi-passive optical network system based on digital subcarrier multiplexing and its dynamic bandwidth allocation method, characterized in that, Includes the following steps: Step S1: Predict bandwidth requirements for each ONU in a multi-PON network, calculate the requirement fulfillment rate, and determine priorities; Step S2: Calculate the bandwidth requirements of each PON; Step S3: Calculate and dynamically allocate a certain number of subcarriers to each PON; Step S4: Dynamically allocate bandwidth to each ONU within the PON according to priority; Adjacent subcarrier activation / deactivation strategy: Within each PON, bandwidth is allocated based on ONU priority. First, the predicted bandwidth requirements of high-priority ONUs are met. If bandwidth resources are insufficient, low-utilization subcarriers of neighboring ONUs within the same PON are released, and then bandwidth allocation is performed for that ONU. If bandwidth resources are still insufficient after releasing subcarriers within the same PON, then subcarrier allocation between different PONs is considered. Global subcarrier reconfiguration: If the bandwidth requirements of the current ONU cannot be met through the above steps, the algorithm will perform a wider range of subcarrier resource reconstruction. Specifically, it will search for subcarrier resources globally, prioritize releasing the subcarriers with the lowest utilization rate or preempting resources serving low-priority ONUs to meet the bandwidth requirements of high-priority or high-demand ONUs. In step S2, the bandwidth requirements of each ONU are calculated based on priority and weighted to determine the bandwidth requirements of each PON, as detailed below: Calculate the total bandwidth requirements of each high-priority PON ONU separately: Total bandwidth requirements of low-priority ONUs: Used to determine the overall bandwidth requirements for each PON: in This is a weighting coefficient used to control the impact of low-priority demands on subcarrier allocation. A larger value will result in higher weighting. value, At that time, more subcarrier resources will be reserved, thereby reducing the frequency of subsequent PON-to-PON subcarrier changes. For demand satisfaction rate, For the threshold, For ONU i Demand forecasts from the previous cycle.

2. The multi-passive optical network system based on digital subcarrier multiplexing and its dynamic bandwidth allocation method according to claim 1, characterized in that, Step S1 involves determining the priority of the ONU, predicting the load, and scheduling subcarriers, as detailed below: Demand Satisfaction Rate Calculation and Dynamic Priority Determination: Based on the ratio of the actual bandwidth allocated to each ONU to the predicted demand, the Demand Satisfaction Rate (DSR) for each ONU is calculated. For the [specific ONU name], the [specific ONU name] is then [calculated]. Each optical network unit (ONU), if , If the threshold value is set, it indicates that the ONU's bandwidth demand fulfillment rate was low in the previous cycle, then... Mark it as high priority; otherwise, mark it as low priority. The definition is as follows: in express The bandwidth actually allocated in the previous cycle For ONU i In the previous cycle's forecasted demand, Load forecasting: Collect the bandwidth demand of ONUs for several previous time periods, and predict the bandwidth demand of ONUs for the next time period using a moving average algorithm. as follows, Where W is the length of the moving average window, that is, the average calculation is performed by selecting data from the past W periods; For the i-th ONU in the past... Actual bandwidth requirements within a cycle It is the predicted bandwidth requirement of the i-th ONU in the next cycle; Subcarrier scheduling: Prioritize allocating subcarriers to high-priority ONUs. When resources are insufficient, implement adjacent subcarrier release, service migration, or global reconfiguration strategies.

3. The multi-passive optical network system based on digital subcarrier multiplexing and its dynamic bandwidth allocation method according to claim 2, characterized in that, Step S3 dynamically adjusts the subcarrier allocation according to the bandwidth requirements of each PON, as follows: Assuming the system has N subcarriers and n PONs, then Number of subcarriers N j as follows: in, for Total bandwidth requirements The number of subcarriers N in the last PON n The following formula will be used to adjust and ensure that all subcarrier resources are allocated: 。 4. The multi-passive optical network system based on digital subcarrier multiplexing and its dynamic bandwidth allocation method according to claim 3, characterized in that, The algorithm for dynamically allocating bandwidth to each ONU within the PON based on priority in step S4 is as follows: After differentiating high-priority and low-priority ONUs based on demand satisfaction rate, bandwidth is allocated to high-priority ONUs first, followed by low-priority ONUs. When allocating bandwidth to ONUs, the current... Unmet needs r i In the subcarrier set, find subcarrier k with remaining capacity and perform a bandwidth allocation. ,renew With the available capacity of the subcarrier; if r i If the value is still greater than 0, the next subcarrier will be allocated. If the bandwidth allocated to the high-priority ONU is insufficient, bandwidth can be released from the neighboring low-utilization subcarriers to meet the requirement.

5. The multi-passive optical network system based on digital subcarrier multiplexing and its dynamic bandwidth allocation method according to claim 4, characterized in that, Implement the adjacent subcarrier activation / deactivation strategy as follows: Calculate the subcarrier utilization and release subcarriers with utilization below the reference threshold, let u k Let k be the utilization rate of subcarrier k. Where b i，k It is allocated to the ONU on subcarrier k i bandwidth, C k For the maximum capacity of this subcarrier, if u k If the value is below the reference threshold U, the subcarrier is considered to be partially or fully released to other ONUs with greater bandwidth requirements. During the release, the original ONU services on the subcarrier will be migrated. (1) Sharing of subcarrier resources among neighboring ONUs within the same PON First, the subcarrier resource status is checked within a single PON. When the bandwidth requirement allocated to a certain ONU cannot be directly met, the algorithm searches for a subcarrier with lower utilization among the neighboring ONUs within that PON, releases some or all of the resources, and allocates them to ONUs with higher requirements to meet the bandwidth needs of high-priority ONUs. (2) Resource sharing of neighboring subcarriers across PON If the bandwidth requirements of the ONU cannot be met after releasing resources within the same PON, a cross-PON subcarrier resource sharing mechanism is further considered. The algorithm dynamically uses low-utilization subcarrier resources within neighboring PONs, temporarily releases them, and reallocates them to PONs with greater bandwidth requirements to optimize the overall network resource utilization efficiency. If the adjacent subcarrier is successfully released, return to step S4 to continue allocating bandwidth to the ONU that was not successfully allocated bandwidth.

6. The multi-passive optical network system based on digital subcarrier multiplexing and its dynamic bandwidth allocation method according to claim 5, characterized in that, The subcarrier activation / deactivation strategy and ONU service migration strategy are as follows: Find neighboring low-priority ONUs and check if their subcarriers can be migrated to other subcarriers or further locations. Release the adjacent subcarrier resources occupied by the ONU to be used by the current high-priority ONU. Determine the subcarrier with the lowest total real-time bandwidth demand of ONUs or the subcarrier with zero ONUs as an idle subcarrier, and migrate the ONUs on the idle subcarrier to other designated subcarriers. During migration, prioritize ONUs with smaller real-time bandwidth demands until the bandwidth utilization of the target subcarrier is not less than 50% of the subcarrier capacity. When migrating ONUs, the target subcarrier should have sufficient remaining capacity to support the real-time bandwidth demand of the migrated ONUs.

7. The multi-passive optical network system based on digital subcarrier multiplexing and its dynamic bandwidth allocation method according to claim 6, characterized in that, Implement global subcarrier reconfiguration as follows: Find the subcarrier with the lowest utilization rate from the global subcarriers and reconfigure it or preempt the bandwidth of low-priority ONUs; after completing the reconfiguration, try to allocate bandwidth to the current ONU; if it still fails, it means that network resources are indeed scarce, and you can wait for the next cycle to allocate. If the global reconfiguration still fails, it means that network resources have reached a bottleneck, abandon more allocation in this cycle, and wait for the next cycle to schedule.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the multi-passive optical network system based on digital subcarrier multiplexing and the dynamic bandwidth allocation method thereof as described in any one of claims 1 to 7.

9. A computer-readable storage medium storing computer instructions thereon, characterized in that, When executed by a processor, the computer instructions implement the passive optical network system based on digital subcarrier multiplexing and the dynamic bandwidth allocation method thereof as described in any one of claims 1-7.

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