Low-voltage power line broadband carrier extended band adaptive selection and OFDMA scheduling method

Abstract

The application discloses a low-voltage power line broadband carrier extended frequency band adaptive selection and OFDMA scheduling method. The method senses multiple candidate extended frequency bands, acquires low-voltage power line channel noise, channel attenuation, external interference, packet error rate, frequency band stability and service load information; performs frequency band quality evaluation according to the above information, dynamically judges whether each candidate extended frequency band is available, and generates an available extended frequency band set; divides the available extended frequency band into OFDMA subcarrier resources or resource units, and performs avoidance or protection processing on subcarriers affected by interference or deep fading; and then performs resource scheduling according to the channel quality of a communication node, service priority, bandwidth demand and waiting time. When the channel state or service load changes, frequency band evaluation, frequency selection and scheduling are re-executed. The scheme can avoid the problem that the communication reliability is reduced due to the influence of noise, attenuation and interference on the fixed frequency band, and improves the extended spectrum utilization rate.

Description

Technical Field

[0001] This invention belongs to the field of low-voltage power line broadband carrier communication technology, specifically relating to a method and system for adaptive selection of extended frequency bands and OFDMA scheduling of low-voltage power line broadband carriers. Background Technology

[0002] Low-voltage power line broadband carrier communication is a technology that uses existing power lines in a low-voltage distribution network as the transmission medium for data communication. It is widely used in scenarios such as electricity consumption information collection, transformer area status monitoring, distributed energy access, charging facility communication, and the Internet of Things (IoT) in low-voltage distribution. Compared with dedicated communication cables or wireless communication methods, low-voltage power line broadband carrier communication does not require the laying of new communication lines and can achieve a wide range of terminal access based on the existing low-voltage power network. It features low deployment costs, coverage of numerous nodes, and suitability for power business scenarios.

[0003] However, low-voltage power lines are not specifically designed for communication, and their channel environment is complex and highly variable. Low-voltage distribution lines typically have multiple branches, multiple joints, impedance discontinuities, and random load connections, resulting in significant differences in channel attenuation across different line sections, time periods, and power load conditions. Simultaneously, numerous power electronic devices on the residential or industrial user side inject noise and interference into the power lines. For example, switching power supplies, frequency converters, inverters, charging equipment, and start / stop devices for household appliances can all generate continuous noise, narrowband interference, or sudden pulse interference. These noises and interferences often exhibit uneven distribution in the frequency domain, leading to better quality in some frequency bands while others may be unavailable for extended periods or short periods.

[0004] Existing low-voltage power line broadband carrier communication systems typically operate within preset frequency bands or transmit data according to fixed frequency band configurations and fixed resource allocation methods. While this approach can meet basic communication needs when the channel environment is relatively stable, in real-world low-voltage power line scenarios, channel noise, line attenuation, external interference, and service load can all vary over time. When a fixed communication frequency band is affected by strong noise, deep fading, or narrowband interference, continued use of that band by the system can easily lead to increased bit error rate, packet error rate, and retransmission count, thereby reducing communication reliability and effective throughput. On the other hand, if the system fails to identify and utilize certain extended frequency bands with good channel quality during a certain period, available spectrum resources will be idle, limiting the carrying capacity of the broadband carrier communication system.

[0005] With the development of low-voltage power distribution services, the types of services carried by communication systems are becoming increasingly diversified. In addition to regular periodic meter readings, these include event alarms, control commands, power outage and restoration information, transformer area status monitoring, parameter distribution, batch data transmission, and remote upgrades. Different services have different requirements for communication resources: alarm and control services typically have high requirements for latency and reliability, ordinary data collection services have relatively lower real-time requirements, while large-volume data transmission or upgrade services are more concerned with available bandwidth and continuous transmission capabilities. If a simple fixed time slot, fixed frequency band, or average allocation method is still used, it is difficult to simultaneously ensure reliable transmission of high-priority services, fair access for ordinary services, and overall spectrum utilization.

[0006] OFDMA technology can further divide available frequency bands into multiple subcarriers or resource units, allowing multiple communication nodes to transmit in parallel on different subcarrier resources, resulting in good spectrum utilization efficiency and multi-user scheduling capabilities. When using OFDMA for low-voltage power line broadband carrier communication, theoretically, resource allocation can be based on the channel quality differences between different nodes on different subcarriers, thereby improving system throughput and anti-interference capabilities. However, if OFDMA resource scheduling is based solely on fixed frequency bands or static resource tables, without considering the real-time availability of extended frequency bands, channel quality changes, and traffic load variations, the advantages of OFDMA in complex low-voltage power line channels cannot be fully realized.

[0007] Therefore, existing technologies have at least the following shortcomings: First, they lack real-time sensing capabilities for extended frequency bands, making it difficult to promptly determine whether candidate extended frequency bands are affected by noise, attenuation, or interference. Second, they lack a frequency band quality evaluation mechanism tailored to the characteristics of low-voltage power line channels, failing to comprehensively reflect factors such as noise, attenuation, interference, packet error rate, and stability. Third, there is a lack of linkage between extended frequency band selection and service load and priority, easily leading to issues such as high-quality frequency bands not prioritizing critical services or low-quality frequency bands still carrying important services. Fourth, the integration of OFDMA subcarrier resource scheduling and extended frequency band availability assessment is not tight, making it difficult to achieve refined resource allocation based on the channel quality and bandwidth requirements of different nodes.

[0008] Based on the above, it is necessary to propose an adaptive selection and OFDMA scheduling method for low-voltage power line broadband carrier extended frequency bands to solve these problems. Summary of the Invention

[0009] The purpose of this invention is to solve the technical problems mentioned in the background section and to provide an adaptive selection and OFDMA scheduling method for low-voltage power line broadband carrier extended frequency bands.

[0010] The objective of this invention is achieved through the following technical solution:

[0011] A method for adaptive selection of broadband carrier spread bands and OFDMA scheduling for low-voltage power lines, characterized by comprising:

[0012] Frequency band sensing is performed on multiple candidate extended frequency bands of a low-voltage power line broadband carrier communication system to obtain information on channel noise, channel attenuation, external interference, frequency band occupancy status, and service load for each candidate extended frequency band.

[0013] Based on the channel noise, channel attenuation, external interference, frequency band occupancy status, and service load information, frequency band quality is evaluated for each candidate extended frequency band, and the corresponding frequency band quality evaluation results are obtained.

[0014] Based on the frequency band quality evaluation results, dynamically determine whether each candidate extended frequency band is a usable extended frequency band, and generate a set of usable extended frequency bands;

[0015] The frequency bands in the available extended frequency band set are divided into OFDMA subcarrier resources or resource units composed of multiple subcarriers;

[0016] Based on the channel quality, service priority, and bandwidth requirements of each communication node on the available extended frequency band, the OFDMA subcarrier resources or resource units are scheduled and allocated, and low-voltage power line broadband carrier communication is carried out according to the scheduling results.

[0017] As a preferred technical solution of the present invention, the frequency band sensing includes: sending a detection signal or receiving a reference signal to each candidate extended frequency band within a preset sensing period or service idle window, and measuring one or more of the following: noise power spectral density, signal received power, signal-to-noise ratio, carrier-to-noise ratio, bit error rate, packet error rate, duration of burst interference, narrowband interference occupancy ratio, and background noise fluctuation amplitude.

[0018] As a preferred technical solution of the present invention, the frequency band quality evaluation includes: normalizing the channel noise index, channel attenuation index, external interference index and frequency band stability index respectively, and calculating the frequency band quality score according to the preset weight or dynamic weight; wherein, the lower the channel noise, the smaller the channel attenuation, the weaker the external interference and the higher the frequency band stability, the higher the frequency band quality score.

[0019] As a preferred technical solution of the present invention, the dynamic determination of whether each candidate extended frequency band is an available extended frequency band includes: when the frequency band quality score of the candidate extended frequency band is not lower than the available threshold, and its interference occupancy ratio, attenuation value and packet error rate meet the corresponding thresholds respectively, the candidate extended frequency band is determined to be an available extended frequency band; when the frequency band quality score is lower than the unavailable threshold, or the duration of sudden interference exceeds a preset time, or the service transmission reliability is lower than the preset requirements, the candidate extended frequency band is determined to be an unavailable extended frequency band.

[0020] As a preferred technical solution of the present invention, a hysteresis threshold and a holding time are set when determining the available extended frequency bands. The candidate extended frequency band is added to the set of available extended frequency bands only after the candidate extended frequency bands have continuously met the availability conditions for a first holding time. The added available extended frequency bands are removed from the set of available extended frequency bands only after the added available extended frequency bands have continuously met the unavailability conditions for a second holding time.

[0021] As a preferred technical solution of the present invention, the step of dividing the frequency bands in the available extended frequency band set into OFDMA subcarrier resources or resource units includes: dividing each available extended frequency band into multiple subcarriers according to a preset subcarrier interval; setting empty carriers or protection subcarriers at locations where there is narrowband interference, deep fading or spectrum boundary protection requirements; and combining multiple continuous or non-contiguous subcarriers into resource units for reuse by different communication nodes.

[0022] As a preferred technical solution of the present invention, the scheduling allocation includes: calculating a scheduling priority for each communication node, wherein the scheduling priority is jointly determined by the communication node's channel quality, service priority, amount of data to be sent, bandwidth requirement, latency requirement, and historically allocated resource amount on the target resource unit; during scheduling, resource units are allocated preferentially to communication nodes with high channel quality, high service priority, and unmet bandwidth requirements.

[0023] As a preferred technical solution of the present invention, for high reliability services or high priority services, resource units with high frequency band quality scores, small interference fluctuations and small attenuation are allocated first; for ordinary services, resource units are allocated according to maximizing spectrum utilization or inter-node fairness constraints, based on meeting the minimum communication reliability requirements.

[0024] As a preferred technical solution of the present invention, the method further includes an adaptive update step: when changes in channel noise, channel attenuation, external interference, frequency band occupancy status or service load are detected and the preset trigger conditions are met, frequency band quality evaluation, available extended frequency band judgment and OFDMA resource scheduling are re-executed, and the allocated resources are maintained, migrated, down-ordered modulated, retransmitted, enhanced or released.

[0025] The present invention also provides a low-voltage power line broadband carrier extended frequency band adaptive selection and OFDMA scheduling system, comprising: an extended frequency band sensing module, a frequency band quality evaluation module, an adaptive frequency selection module, and an OFDMA resource scheduling module;

[0026] The extended frequency band sensing module is used to acquire channel noise, channel attenuation, external interference, frequency band occupancy status, and service load information of multiple candidate extended frequency bands.

[0027] The frequency band quality evaluation module is used to generate frequency band quality evaluation results based on the channel noise, channel attenuation, external interference, frequency band occupancy status, and service load information.

[0028] The adaptive frequency selection module is used to dynamically generate a set of available extended frequency bands based on the frequency band quality evaluation results.

[0029] The OFDMA resource scheduling module is used to divide the available extended frequency band set into OFDMA subcarrier resources or resource units, and to perform resource scheduling according to the channel quality, service priority and bandwidth requirements of the communication nodes.

[0030] This invention continuously or triggeredly senses candidate extended frequency bands for broadband carriers on low-voltage power lines, comprehensively acquiring information such as channel noise, channel attenuation, external interference, packet error rate, frequency band stability, and service load. Based on this, it performs frequency band quality evaluation and availability assessment, dynamically identifying currently available extended frequency bands for communication. Compared to fixed-band communication methods, this invention avoids the system from occupying frequency bands affected by strong noise, deep fading, or narrowband interference for extended periods, reducing bit error rate, packet error rate, and retransmission count, and improving communication reliability in complex low-voltage power line channel environments.

[0031] This invention further divides the selected available extended frequency bands into OFDMA subcarrier resources or resource units, and schedules them according to the channel quality differences of each communication node in different resource units. This allows nodes with better channel conditions to prioritize the use of subcarrier resources with higher matching degrees, while subcarriers affected by interference or deep fading are treated with empty carriers, guarded subcarriers, or downgraded. This fully utilizes the frequency domain differences between different extended frequency bands and different subcarriers, improving the utilization rate of extended spectrum resources and the effective throughput of the system.

[0032] This invention further integrates service priority, bandwidth requirements, waiting time, and historical resource usage during OFDMA resource scheduling. It prioritizes the allocation of high-quality resources to high-priority services such as alarms, control, and event reporting, while ensuring fair scheduling and bandwidth guarantees for ordinary data acquisition or batch backhaul services. When channel conditions or service load change, the system can re-execute frequency band evaluation, frequency selection, and resource scheduling, achieving dynamic matching between frequency band selection and service requirements. This enhances the multi-service carrying capacity and operational stability of low-voltage power line broadband carrier communication systems. Attached Figure Description

[0033] Figure 1 : Flowchart of the method of the present invention;

[0034] Figure 2 : System block diagram of the present invention. Detailed Implementation

[0035] The present invention will be further described below with reference to specific embodiments. It should be understood that the following embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention; without departing from the core concept of the present invention, those skilled in the art can make adaptive adjustments to the number of frequency bands, subcarrier spacing, evaluation weights, threshold parameters and scheduling strategies.

[0036] Example 1: See Figure 1 and Figure 2 This embodiment provides an adaptive selection and OFDMA scheduling method for broadband carrier extended frequency bands on low-voltage power lines, applicable to broadband carrier communication between concentrators, data collectors, smart meters, or other power line communication nodes within a low-voltage distribution area. The system pre-configures several candidate extended frequency bands, which can be several continuous or discontinuous frequency intervals permitted for use outside the main communication frequency band. Because low-voltage power line channels are affected by factors such as the start / stop of household appliances, switching power supplies, inverters, line branches, and changes in load access, different extended frequency bands may exhibit different noise, attenuation, and interference states at different times. Therefore, this embodiment does not use fixed extended frequency bands, but instead performs periodic or event-triggered sensing of candidate extended frequency bands and dynamically determines the available extended frequency bands based on the sensing results.

[0037] Specifically, after the communication system is initialized, the concentrator or master control communication node establishes a list of candidate extended frequency bands and sets the band number, frequency range, allowable transmit power, guard bandwidth, subcarrier spacing, and initial availability status for each candidate extended frequency band. Within a preset sensing period, or after events such as a sudden increase in traffic, a rise in packet error rate, an increase in retransmission count, node joining the network, or node leaving the network, the system performs extended frequency band sensing on the candidate extended frequency bands. During sensing, the master control communication node can send a probe signal, and each subordinate communication node can provide feedback on received power, signal-to-noise ratio, bit error rate, or packet error rate; alternatively, each node can listen to the candidate extended frequency bands within a specified quiet window, measuring background noise power spectral density, narrowband interference occupancy ratio, duration of sudden interference, and noise fluctuation amplitude. For scenarios where service cannot be interrupted for extended periods, the sensing process can be interspersed during service downtime, and multiple measurement results can be averaged or weighted smoothed to reduce the impact of instantaneous noise on the frequency selection results.

[0038] After acquiring the sensing data, the system evaluates the frequency band quality for each candidate extended frequency band. Evaluation metrics include at least channel noise, channel attenuation, external interference, and frequency band stability. These metrics can also be further combined with current service load, the amount of data to be transmitted, and historical transmission success rates. For a given candidate extended frequency band, a higher quality score is awarded if its noise power is low, path attenuation is small, burst interference duration is short, narrowband interference occupancy is low, and historical packet error rate is low. Conversely, a lower quality score is awarded if the frequency band experiences persistent narrowband interference, deep fading, or a significantly increased packet error rate. In practical implementation, each metric can be normalized to a uniform value range before calculating the frequency band quality score according to preset weights. For example, the system can set noise weights, attenuation weights, interference weights, and stability weights, and dynamically adjust these weights based on the substation environment; increasing the interference weight in scenarios with drastic interference changes, and increasing the attenuation weight in long-distance or complex branch line scenarios.

[0039] After completing the frequency band quality evaluation, the system dynamically generates a set of available extended frequency bands based on the evaluation results. For candidate extended frequency bands with a quality score not lower than the availability threshold, and whose attenuation value, interference occupancy ratio, and packet error rate meet their respective thresholds, the system classifies them as available extended frequency bands. For candidate extended frequency bands with a quality score lower than the unavailability threshold, or whose burst interference duration exceeds a preset time, or whose continuous transmission reliability is lower than a preset requirement, the system classifies them as unavailable extended frequency bands. To avoid frequent switching of frequency band status near the threshold, this embodiment sets a hysteresis threshold and a hold-in time. That is, a candidate extended frequency band is added to the set of available extended frequency bands only after continuously meeting the availability conditions for a first hold-in time, and an already added available extended frequency band is removed only after continuously meeting the unavailability conditions for a second hold-in time. This method avoids frequent start-up and shutdown of frequency bands due to instantaneous spike noise, improving scheduling stability.

[0040] Once the set of available extended frequency bands is determined, the system divides each available extended frequency band into multiple OFDMA subcarriers according to a preset subcarrier spacing, and sets guard subcarriers or empty carriers based on spectrum boundaries, guard bandwidth, and interference locations. If some subcarriers are located near narrowband interference centers, or exhibit significant deep fading in historical transmissions, the system marks these subcarriers as unschedulable subcarriers; the remaining subcarriers that meet the conditions can be scheduled individually, or multiple consecutive or non-consecutive subcarriers can be combined into resource units. For services with low bandwidth requirements such as meter reading and status reporting, a small number of resource units can be allocated; for services with high bandwidth requirements such as firmware upgrades and batch data backhaul, multiple resource units can be allocated or resource units can be allocated across extended frequency bands.

[0041] During the OFDMA resource scheduling phase, the system generates scheduling results based on the channel quality, service priority, and bandwidth requirements of communication nodes. The channel quality of a communication node can be determined by its signal-to-noise ratio, packet error rate, historical success rate, and modulation / coding support level in each resource unit. Service priority can be determined based on service type; for example, services with high real-time or reliability requirements, such as alarms, control, cost control, and event reporting, have higher priority, while ordinary periodic data collection services have lower priority. Bandwidth requirements can be determined by the amount of data to be transmitted, the maximum allowable delay, and the remaining transmission window. The system calculates the scheduling priority for each node in each resource unit, prioritizing resource units with high frequency band quality, low interference fluctuations, and good node channel quality for high-priority services. Simultaneously, it sets minimum resource guarantees for ordinary services to prevent low-priority nodes from being deprived of transmission opportunities for extended periods.

[0042] For example, within a distribution area, candidate extended frequency bands include F1, F2, F3, and F4. System detection reveals that F1 has low noise but high service occupancy, F2 experiences persistent narrowband interference, F3 has low attenuation and a low packet error rate, and F4 experiences burst interference during certain time periods. After frequency band quality evaluation, F1 and F3 are added to the available extended frequency band set, F2 is deemed unavailable, and F4 is temporarily excluded due to burst interference not yet meeting the hold-up time requirement. The system then divides F1 and F3 into multiple OFDMA resource units. A portion of F1 subcarriers are set as empty carriers due to proximity to interfering frequencies, while most of F3 subcarriers are available for scheduling. For node A reporting alarm data, the system prioritizes allocating resource units with higher channel quality from F3; for node B performing normal periodic data acquisition, the system allocates resource units from F1 that meet the minimum reliability requirements; for node C with significant data backhaul needs, the system combines and allocates multiple resource units from F1 and F3. Through this processing, the system can achieve parallel transmission across multiple nodes even with dynamic changes in extended frequency bands, improving spectrum utilization and communication reliability.

[0043] During communication, the system continuously monitors channel and service status. When it detects a rapid increase in noise, abnormally increased attenuation, packet error rate exceeding a threshold, or significant changes in service load in an available extended frequency band, the system re-executes frequency band quality assessment and OFDMA scheduling. For allocated resources, if the corresponding frequency band only fluctuates briefly, the system can maintain the current allocation and reduce the modulation and coding level or increase retransmission redundancy; if the corresponding frequency band remains unavailable, the system will migrate the relevant services to other available extended frequency bands or release the corresponding resource units. Thus, this embodiment forms a closed-loop control process of "extended frequency band sensing, frequency band quality assessment, adaptive frequency selection, OFDMA resource scheduling, and status feedback update".

[0044] Example 2: This example provides another adaptive selection and OFDMA scheduling method for low-voltage power line broadband carrier extended bands, primarily applicable to low-voltage power line communication scenarios with significant service load variations. For example, when multiple services coexist, such as daily periodic data collection, centralized meter reading, event alarms, and remote upgrades, this method performs joint scheduling of extended bands and OFDMA resources. The basic process of this example is the same as Example 1, but the difference lies in the fact that this example further introduces service load levels and service priority constraints in band quality evaluation and resource scheduling. This ensures that the extended band selection reflects not only the physical channel state but also the current service requirements for bandwidth, latency, and reliability.

[0045] In this embodiment, the system divides services into at least two categories: the first category is high-priority services, including alarm events, control commands, and critical status reporting, which have high requirements for latency or reliability; the second category is ordinary services, including periodic data reading and routine data return, which have relatively low requirements for latency. If necessary, a third category of high-bandwidth services can also be set, such as batch parameter distribution, firmware upgrades, or centralized data synchronization. The system configures different minimum channel quality requirements, maximum allowable latency, minimum bandwidth guarantees, and retransmission strategies for different services. High-priority services require higher frequency band quality and more stable resource units; ordinary services can use resource units with slightly lower quality but still communicable while meeting minimum reliability requirements; high-bandwidth services focus more on the number of continuous or aggregateable resource units.

[0046] During the frequency band awareness phase, the system not only collects noise, attenuation, interference, and stability data for each candidate extended frequency band, but also statistically analyzes the service load status in the current transmission queue, including the amount of data to be transmitted, waiting time, service priority, number of target nodes, and historical resource fulfillment rate for each service type. Subsequently, the system calculates the basic frequency band quality score for the candidate extended frequency bands and generates an extended frequency band usage strategy based on the service load. For example, when there is data to be transmitted in the high-priority service queue, the system increases the influence of frequency band stability and packet error rate indicators in the evaluation, allowing extended frequency bands with low noise, low attenuation, and low packet error rate to be prioritized for use in the high-reliability resource pool. When the volume of ordinary services is large but real-time requirements are not high, the system can appropriately expand the set of available extended frequency bands, using frequency bands with quality scores that meet basic communication requirements but have slightly lower stability for ordinary service transmission. When high-bandwidth services arrive, the system prioritizes extended frequency bands with a large number of aggregable subcarriers and a more dispersed interference distribution.

[0047] In OFDMA resource allocation, this embodiment further divides the available extended frequency bands into high-reliability resource units, ordinary resource units, and reserve resource units. High-reliability resource units are derived from a set of subcarriers with high quality scores, low interference fluctuations, and low packet error rates, and are prioritized for high-priority services. Ordinary resource units are derived from a set of subcarriers that meet basic communication thresholds and are used for periodic data collection and regular data services. Reserve resource units are not prioritized under normal circumstances; they are only temporarily activated based on real-time evaluation results when high-reliability resource units are insufficient or when service load suddenly increases. This allocation method is not fixed; the system adjusts the resource unit category as the sensing results are updated. For example, if a resource unit experiences a decrease in packet error rate and reduced interference over several consecutive periods, it can be upgraded from an ordinary resource unit to a high-reliability resource unit; conversely, it can be downgraded to an ordinary resource unit or a reserve resource unit.

[0048] During scheduling, the system prioritizes high-priority services. For each high-priority service node, the system selects the resource unit with the best or near-best channel quality from the high-reliability resource units and allocates one or more resource units based on the bandwidth required by the service. When multiple high-priority services request resources simultaneously, the system determines the scheduling order based on service priority, waiting time, and remaining delay margin. For ordinary services, the system allocates resources from the remaining resources according to bandwidth requirements and fairness, preventing a few nodes with better channel conditions from occupying most of the extended frequency band resources for extended periods. For high-bandwidth services, the system can aggregate and allocate multiple continuous or non-contiguous resource units, but must ensure that the minimum resource guarantee for high-priority services is not compromised.

[0049] For example, during peak meter reading periods, the system detects a significant increase in the load of ordinary services, while some nodes upload event alarms. After evaluation of candidate extended frequency bands F1, F2, and F3, F1 has the highest quality score and the least interference fluctuation; F2 has a medium quality score but a large number of available subcarriers; and F3 exhibits intermittent interference. The system classifies most resource units in F1 as high-reliability resource units, resource units in F2 as ordinary resource units, and some resource units in F3 that temporarily meet the threshold as backup resource units. Subsequently, the system first allocates high-reliability resource units in F1 to event alarm nodes to ensure timely and reliable alarm transmission; then it allocates ordinary resource units in F2 to ordinary meter reading nodes. When the backlog of ordinary service queues exceeds a preset threshold and the duration of interference in F3 is below the threshold, the system temporarily activates backup resource units in F3 to participate in ordinary service scheduling. If subsequent interference in F3 increases and leads to a higher packet error rate, the system stops allocating new services to F3 and migrates unfinished services to F2 or waits for the next scheduling cycle.

[0050] This embodiment can also include a scheduling feedback mechanism. At the end of each scheduling cycle, the system statistically analyzes the actual transmission success rate, retransmission count, average latency, and resource utilization of each resource unit, and feeds this data back to the frequency band quality evaluation module. If a certain extended frequency band scores highly in the sensing phase but experiences a persistently high number of retransmissions during actual transmission, the system reduces the subsequent evaluation weight of that frequency band or raises its availability threshold. If a certain extended frequency band performs stably over a long period but has low resource utilization, the system can prioritize its use when service load increases. Through this feedback mechanism, the system can not only select frequencies based on instantaneous channel conditions but also correct frequency band evaluation results based on actual service transmission performance, making extended frequency band selection and OFDMA scheduling more adaptable to the dynamic changes of low-voltage power line channels.

[0051] In the two embodiments described above, frequency band awareness, frequency band quality evaluation, adaptive frequency selection, and OFDMA resource scheduling can be performed by a concentrator, a master station communication module, a broadband carrier communication module, or other communication nodes with control capabilities, or they can be performed collaboratively by multiple communication nodes. The system used to implement the above methods may include an extended frequency band awareness module, a frequency band quality evaluation module, an adaptive frequency selection module, and an OFDMA resource scheduling module. The extended frequency band awareness module is used to acquire channel noise, channel attenuation, external interference, frequency band occupancy status, and service load information of candidate extended frequency bands; the frequency band quality evaluation module is used to generate frequency band quality evaluation results; the adaptive frequency selection module is used to dynamically generate a set of available extended frequency bands; and the OFDMA resource scheduling module is used to divide the available extended frequency bands into subcarrier resources or resource units and schedule them according to the channel quality, service priority, and bandwidth requirements of the communication nodes. These modules can be implemented using software programs, hardware circuits, digital signal processors, field-programmable gate arrays, or combinations thereof.

[0052] Through the above implementation methods, the present invention can dynamically determine which extended frequency bands are available based on changes in low-voltage power line channel noise, attenuation, interference, and service load. It can further subdivide the available extended frequency bands into OFDMA subcarrier resources for multi-node scheduling, thereby avoiding the problem of communication reliability degradation caused by increased interference or load changes in fixed frequency bands, improving the utilization rate of extended spectrum resources, and enhancing the transmission stability and service carrying capacity of low-voltage power line broadband carrier communication systems in complex channel environments.

[0053] Example 3: This example, based on the previous examples, provides an implementation method with a scoring formula and scheduling constraints. For ease of explanation, let the candidate extended frequency band set be... ,in Indicates the first There are candidate extended frequency bands; the set of communication nodes is: ,in Indicates the first There are one communication node; the set of schedulable resource units is: Each resource unit consists of one or more OFDMA subcarriers. For the first... The system obtains normalized noise indices within a candidate extended frequency band during the sensing period. Normalized decay index Normalized interference index Normalized error rate index and normalized volatility index The values ​​for the above indicators all range from [0,1], with larger values ​​indicating stronger adverse effects. For example, The larger the value, the stronger the background noise in that frequency band. A larger value indicates greater channel attenuation in that frequency band. The larger the value, the more severe the impact of narrowband interference or sudden interference on that frequency band. A larger value indicates a higher historical or current packet error rate. The larger the value, the more pronounced the fluctuations in that frequency band within a continuous sensing period.

[0054] The system calculates the first according to the following formula. Band quality score for each candidate extended band

[0055]

[0056] in, , , , , The weights are respectively for noise, attenuation, interference, packet errors, and fluctuations, and satisfy the following:

[0057]

[0058] In one implementation, the system can be set , , , , When there are many sudden interferences in the low-voltage power line environment, it can improve... and When the attenuation problem is more pronounced due to longer lines and more branches, it can be improved. The aforementioned weights can be pre-configured or dynamically adjusted based on actual transmission statistics. The system determines the usability of a frequency band based on both the frequency band quality score and individual thresholds.

[0059] Let the available entry threshold be... The exit threshold is ,and When the first The candidate extended frequency bands satisfy:

[0060]

[0061] If the above conditions are met continuously for a first hold time, the system adds the candidate extended frequency band to the set of available extended frequency bands.

[0062] When a frequency band that is already available meets the following conditions:

[0063]

[0064] If any of its noise, attenuation, interference, or packet error indicators exceeds the corresponding exit threshold and persists for the second hold-up time, the system will remove the frequency band from the set of available extended frequency bands. This can be achieved by setting... and The difference can be used to determine hysteresis, avoiding frequent band switching when the band quality score fluctuates near the threshold. For extended frequency bands determined to be usable, the system divides OFDMA subcarriers according to subcarrier spacing and combines several subcarriers into resource units. Let the first... Each resource unit is It can provide bandwidth of .

[0065] For the The communication node at the ... The scheduling priority on each resource unit can be calculated by the system using the following formula:

[0066]

[0067] in, Indicates the first The communication node at the ... The normalized channel quality on a resource unit indicates that the node has a higher signal-to-noise ratio, a lower packet error rate, or can support a higher modulation and coding level on that resource unit. This indicates the priority of the service. Higher values ​​are assigned to services such as alarms, control, and event reporting, while lower values ​​are assigned to services that collect data periodically. Indicates normalized bandwidth requirements; Indicates the normalization wait time; This indicates the historical resource usage ratio, used to curb excessive resource usage by a particular node over a long period. , , , , The values ​​for the above normalization quantities can be set to [0, 1].

[0068] During scheduling and allocation, the system uses This serves as the basis for resource unit allocation, and satisfies the following constraint: each resource unit is allocated to at most one communication node within the same scheduling cycle, i.e.:

[0069]

[0070] in, Assign variables to resources, when the first The resource unit is allocated to the first When there are multiple communication nodes, ,otherwise For the first The total bandwidth obtained by each communication node is:

[0071]

[0072] Under the premise of meeting the minimum bandwidth and reliability requirements of high-priority services, the system prioritizes resource allocation results that maximize overall scheduling benefits. Its scheduling objective can be expressed as:

[0073]

[0074] Additionally, minimum bandwidth constraints can be set for high-priority service nodes:

[0075]

[0076] in, For the first The system determines the minimum guaranteed bandwidth required for the current service of each communication node. For ordinary service nodes, if currently available resources are insufficient, the system can allow them to continue queuing in subsequent scheduling cycles and increase bandwidth as needed. This approach increases subsequent scheduling opportunities, thus balancing service priority and fairness among nodes. For example, at a given moment, the system has three candidate extended frequency bands. , , After perception and normalization processing, we obtain , , If set , ,and and If the noise, attenuation, interference, and packet error indicators do not exceed the individual threshold, then the system will... and Determined to be an available extended frequency band, These will not be included in the available extended frequency band set for the time being. Subsequently, the system will... and The system is divided into multiple OFDMA resource units, and the performance of each communication node in each resource unit is calculated separately. If node An alarm is being sent; its priority is... Higher, and in Channel quality on several resource units If the resource units are higher, they will be preferentially allocated to the nodes. If node Performing regular periodic data collection is a service with lower priority than... But the waiting time If the time is too long, the system will prioritize high-priority tasks before processing other tasks. Allocate remaining resource units to avoid long-term backlog of ordinary business operations.

[0077] The formulas in this embodiment are only used to illustrate an implementable frequency band evaluation and resource scheduling method, and do not limit the present invention to using the exact same weights, thresholds, or optimization objectives. In practical applications, the above weights, thresholds, hold times, resource unit granularity, and scheduling objective functions can be adjusted according to the scale of the low-voltage power line network, service type, communication reliability requirements, and chip implementation capabilities. As long as it still judges the availability of extended frequency bands based on low-voltage power line channel noise, attenuation, interference, and service load changes, and further divides the available extended frequency bands into OFDMA subcarrier resources and schedules them according to node channel quality, service priority, and bandwidth requirements, it is an implementation method of the technical solution of the present invention.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for adaptive selection and OFDMA scheduling of low-voltage power line broadband carrier extended frequency bands, characterized in that, include: Frequency band sensing is performed on multiple candidate extended frequency bands of a low-voltage power line broadband carrier communication system to obtain information on channel noise, channel attenuation, external interference, frequency band occupancy status, and service load for each candidate extended frequency band. Based on the channel noise, channel attenuation, external interference, frequency band occupancy status, and service load information, frequency band quality is evaluated for each candidate extended frequency band, and the corresponding frequency band quality evaluation results are obtained. Based on the frequency band quality evaluation results, dynamically determine whether each candidate extended frequency band is a usable extended frequency band, and generate a set of usable extended frequency bands; The frequency bands in the available extended frequency band set are divided into OFDMA subcarrier resources or resource units composed of multiple subcarriers; Based on the channel quality, service priority, and bandwidth requirements of each communication node on the available extended frequency band, the OFDMA subcarrier resources or resource units are scheduled and allocated, and low-voltage power line broadband carrier communication is carried out according to the scheduling results.

2. The method according to claim 1, characterized in that, The frequency band sensing includes: sending a detection signal or receiving a reference signal to each candidate extended frequency band within a preset sensing period or service idle window, and measuring one or more of the following: noise power spectral density, signal received power, signal-to-noise ratio, carrier-to-noise ratio, bit error rate, packet error rate, duration of burst interference, narrowband interference occupancy ratio, and background noise fluctuation amplitude.

3. The method according to claim 1, characterized in that, The frequency band quality evaluation includes: normalizing the channel noise index, channel attenuation index, external interference index, and frequency band stability index respectively, and calculating the frequency band quality score according to preset weights or dynamic weights; wherein, the lower the channel noise, the smaller the channel attenuation, the weaker the external interference, and the higher the frequency band stability, the higher the frequency band quality score.

4. The method according to claim 3, characterized in that, The dynamic determination of whether each candidate extended frequency band is an available extended frequency band includes: when the frequency band quality score of the candidate extended frequency band is not lower than the available threshold, and its interference occupancy ratio, attenuation value and packet error rate meet the corresponding thresholds, the candidate extended frequency band is determined to be an available extended frequency band; when the frequency band quality score is lower than the unavailable threshold, or the duration of sudden interference exceeds a preset time, or the service transmission reliability is lower than the preset requirements, the candidate extended frequency band is determined to be an unavailable extended frequency band.

5. The method according to claim 4, characterized in that, When determining available extended frequency bands, a hysteresis threshold and a hold-up time are set. A candidate extended frequency band is added to the set of available extended frequency bands only after it has continuously met the availability conditions for a first hold-up time. And an already added available extended frequency band is removed from the set of available extended frequency bands only after it has continuously met the unavailability conditions for a second hold-up time.

6. The method according to claim 1, characterized in that, The step of dividing the available extended frequency bands into OFDMA subcarrier resources or resource units includes: dividing each available extended frequency band into multiple subcarriers according to a preset subcarrier interval; setting empty carriers or protection subcarriers at locations where there is narrowband interference, deep fading, or spectrum boundary protection requirements; and combining multiple continuous or non-contiguous subcarriers into resource units for reuse by different communication nodes.

7. The method according to claim 1, characterized in that, The scheduling allocation includes: calculating a scheduling priority for each communication node, the scheduling priority being jointly determined by the communication node's channel quality, service priority, amount of data to be transmitted, bandwidth requirement, latency requirement, and historically allocated resource amount on the target resource unit; during scheduling, resource units are allocated preferentially to communication nodes with high channel quality, high service priority, and unmet bandwidth requirements.

8. The method according to claim 7, characterized in that, For high-reliability or high-priority services, resource units with high frequency band quality scores, low interference fluctuations, and low attenuation are allocated first. For ordinary services, resource units are allocated based on maximizing spectrum utilization or inter-node fairness constraints, while meeting the minimum communication reliability requirements.

9. The method according to claim 1, characterized in that, The method further includes an adaptive update step: when changes in channel noise, channel attenuation, external interference, frequency band occupancy status, or service load are detected and the preset trigger conditions are met, frequency band quality evaluation, available extended frequency band judgment, and OFDMA resource scheduling are re-executed, and the allocated resources are maintained, migrated, down-modulated, enhanced by retransmission, or released.

10. A low-voltage power line broadband carrier extended frequency band adaptive selection and OFDMA scheduling system, characterized in that, include: Extended band sensing module, band quality evaluation module, adaptive frequency selection module, and OFDMA resource scheduling module; The extended frequency band sensing module is used to acquire channel noise, channel attenuation, external interference, frequency band occupancy status, and service load information of multiple candidate extended frequency bands. The frequency band quality evaluation module is used to generate frequency band quality evaluation results based on the channel noise, channel attenuation, external interference, frequency band occupancy status, and service load information. The adaptive frequency selection module is used to dynamically generate a set of available extended frequency bands based on the frequency band quality evaluation results. The OFDMA resource scheduling module is used to divide the available extended frequency band set into OFDMA subcarrier resources or resource units, and to perform resource scheduling according to the channel quality, service priority and bandwidth requirements of the communication nodes.

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