A method for evaluating the load capacity of multi-hop dual-mode communication networks

Abstract

This invention discloses a method for evaluating the load capacity of multi-hop dual-mode communication networks, relating to the field of power distribution communication IoT technology. It solves the technical problem that existing network analysis lacks the ability to evaluate the load capacity of field networks with multiple links and dual-mode media communication. The method includes: S1, establishing a first objective function to maximize the throughput of a single network in a multi-hop dual-mode network; S2, constructing constraints on the first objective function based on the half-duplex mechanism of communication equipment and the limitations imposed by information flow transmission requirements on network resource allocation; S3, introducing a satisfaction function to improve the first objective function, forming a second objective function; S4, obtaining a third objective function with integer constraints to optimize the throughput of multiple networks based on the first and second objective functions; and S5, using the throughput of the optimal solution of the third objective function as the load capacity of the multi-hop dual-mode communication network. The evaluation results of this invention are more consistent with network characteristics and provide valuable reference for optimizing the performance of multiple networks.

Description

Technical Field

[0001] This invention relates to the field of power distribution communication Internet of Things (IoT) technology, and in particular to a method for evaluating the load capacity of a multi-hop dual-mode communication network. Background Technology

[0002] Power line carrier communication (PLC) is a communication method that uses power transmission lines as the medium. Power transmission lines have robust installation support structures, and utilizing existing power lines for communication reduces the cost and engineering difficulty of building new communication lines. Furthermore, power lines are widely distributed, have broad coverage, and their medium is mostly three-phase good conductors with low line loss. Therefore, using power transmission lines to simultaneously transmit signals and energy is both economical and reliable. PLC is highly favored by the power sector and is widely deployed in low-voltage distribution networks to facilitate the upward and downward communication of marketing and business operations. In recent years, with the rise of the Internet of Things (IoT), "Internet of Everything" is an inevitable trend in IoT development. Deeply integrating traditional power industry technologies with IoT technologies will greatly improve the operational efficiency and profitability of power companies: A comprehensive interconnected relationship will be formed between distribution network equipment, allowing the main control center to fully perceive the distribution network, forming a new information network system and improving the intelligence level of the power grid; real-time and comprehensive monitoring of terminal power consumption will enable timely troubleshooting when power outages occur, improving the quality of power supply services and user satisfaction; and the deep integration of traditional power industry technologies with IoT technologies will expand the business scope and innovation space of power companies, helping the power industry adapt to the new situation of energy transition and market competition. Against this backdrop, distribution transformer substations will connect to a massive number of power distribution devices, leading to a surge in network traffic. Furthermore, these substations cover large areas and operate in extremely complex environments, making existing power line carrier communication completely inadequate for meeting the demands of massive device access and reliable information transmission. Therefore, a new network communication technology, Multi-mode & Deep-Coverage Field Area Network (MuCoFAN), has emerged as a solution for the "last mile" network of the Internet of Things (IoT). By constructing a field sensing hub network using both power line carrier and radio frequency (RF) transmission media, and using this as a field network platform, it combines multiple transmission modes, standards, and methods to form a multi-dimensional and multi-form local heterogeneous communication network. This not only provides wide-area IoT communication service coverage but also supports the access of various types of IoT devices, breaking down fragmented and differentiated communication barriers in complex IoT scenarios and demonstrating extremely high application potential. Currently, this field area network has been deployed in actual power distribution IoT applications. The high reliability, flexible networking performance, and higher throughput of the dual-mode media have brought a simplified network structure, lower construction costs, and efficient operation and maintenance strategies to power distribution IoT. For such a highly efficient and reliable network, it is valuable to conduct in-depth research and evaluation of its capacity.

[0003] Current research on power line carrier communication mainly focuses on the performance analysis of single-carrier media and single-hop links, without addressing the load capacity assessment of field networks for multi-hop links and dual-mode media communication. Complex routing, dynamically changing noise, and channel environments make capacity analysis of multi-standard, multi-dimensional, heterogeneous field networks a significant challenge; currently, there is no research on the throughput load of multi-hop relay networks. Furthermore, with the increasing access to service acquisition during power system distribution network operation and maintenance, higher demands are placed on network capacity; therefore, the assessment and optimization of field network carrying capacity are essential.

[0004] In the process of realizing this invention, the inventors discovered at least the following problems in the prior art:

[0005] Existing technologies mainly focus on network performance evaluation for single-carrier media and single-hop links, lacking evaluation of field network load capacity for multi-link and dual-mode media communication. Summary of the Invention

[0006] The purpose of this invention is to provide a method for evaluating the load capacity of multi-hop dual-mode communication networks, thereby addressing the technical problem that existing technologies mainly focus on evaluating the network performance of single-carrier media and single-hop links, lacking the ability to evaluate the load capacity of field networks with multiple links and dual-mode media communication. The various technical effects of the preferred solutions among the many technical solutions provided by this invention are detailed below.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention provides a method for evaluating the load capacity of a multi-hop dual-mode communication network, comprising:

[0009] S1. Construct a multi-hop dual-mode communication network model, and establish a first objective function based on maximizing the throughput of a single network in the multi-hop dual-mode network;

[0010] S2. Construct the constraints of the first objective function based on the half-duplex mechanism of communication equipment and the constraints of information flow transmission requirements on network resource allocation;

[0011] S3. Introduce a satisfaction function to improve the first objective function, forming a second objective function;

[0012] S4. Based on the first objective function and the second objective function, obtain the third objective function with integer constraints that optimizes the throughput of multiple networks;

[0013] S5. The throughput under the optimal solution of the third objective function is taken as the load capacity of the multi-hop dual-mode communication network.

[0014] Preferably, step S1, establishing the first objective function, includes:

[0015] S11. Introduce a resource allocation parameter to represent the normalized occupancy of the information flow, and obtain the transmission rate of the information flow on each link in a single network transmission.

[0016] S12. The minimum value of the transmission rate of one of the information streams is taken as the end-to-end throughput rate.

[0017] S13. Maximize the sum of the throughput rates of all information flows within a single network as the first objective function.

[0018] Preferably, the sum of the throughput rates is:

[0019]

[0020] in, For the normalized occupancy, I t Let l be the information flow, l be the link, f be the channel; I be the information flow set; L be the link set; F be the channel set; C be the information flow set. l,f The transmission rate is [value].

[0021] Preferably, the limitations of the communication device's half-duplex mechanism on network resource allocation in step S2 include:

[0022] T1. The sum of the normalized occupancy of the information flow transmitted in the same frequency interference link set on the channel is less than the proportion of resource blocks occupied by the channel within the unit;

[0023] T2. The number of time slots used for processing information streams at each tail end is less than 1.

[0024] Preferably, the restrictions on network resource allocation imposed by the information flow transmission demand in step S2 include:

[0025] T3. The transmission rate of a single information stream is equal across multiple links;

[0026] T4, the range of the transmission rate is: Among them, A t ={A 1 A 2 A 3 …} represents the transmission requirements of different information streams; [T min ,T max ] represents the time interval within which the information stream needs to be successfully transmitted within a single link; R th This represents the upper limit of the transmission rate of a single information stream on the link;

[0027] T5. The normalized occupancy varies continuously between 0 and 1, and the normalized occupancy in the power line carrier channel does not exceed 1 / 3.

[0028] T6. The normalized occupancy of the information flow on links that it does not pass through is always 0.

[0029] Preferably, step S3 includes: inputting the ratio of the first objective function to the transmission requirements of different information flows as an independent variable into the satisfaction function to obtain the second objective function.

[0030] Preferably, the satisfaction function is: S(x) = -e -(x-1) , where x is the independent variable.

[0031] Preferably, step S4 includes:

[0032] S41. Solve the discrete relationship between single network throughput and the duration coefficient according to the first objective function and the second objective function; wherein, the duration coefficient is the time slot length occupied by each tail transmission;

[0033] S42. The sum of all the single network throughputs is taken as the multi-network throughput;

[0034] S43. Introduce an indicator variable and, based on the relationship between the single network throughput and the persistence coefficient, obtain the third objective function representing the multi-network throughput.

[0035] Preferably, the constraint condition for constructing the third objective function is to avoid mutual interference between the individual networks.

[0036] Preferably, the optimal solution of the first objective function represents the load capacity of the single network; the optimal solution of the second objective function represents the load capacity of the single network under the balanced allocation of network resources.

[0037] Implementing one of the above-described technical solutions of the present invention has the following advantages or beneficial effects:

[0038] This invention proposes a dual-mode communication network load capacity assessment method that introduces a resource allocation factor to analyze the throughput load capacity of single and multiple distribution IoT networks with multi-hop transmission, dual-mode transmission, and frequency hopping mechanisms. Because information flow transmission in this type of distribution IoT requires multiple layers of relays, the necessary resources need to be rationally allocated when multiple information flows converge. Furthermore, this invention considers the frequency hopping mechanism, dual-mode transmission, and the resource requirements of each information flow. Therefore, the performance analysis method of this invention considers influencing factors more comprehensively, and the assessment results are more consistent with network characteristics, providing valuable reference for optimizing the performance of multiple networks. Attached Figure Description

[0039] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0040] Figure 1 This is a flowchart of a method for evaluating the load capacity of a multi-hop dual-mode communication network according to an embodiment of the present invention;

[0041] Figure 2 This is a field network topology diagram of the multi-hop dual-mode communication network model according to an embodiment of the present invention;

[0042] Figure 3 This is a comparison diagram of the frequency hopping mode and the single-channel mode in an embodiment of the present invention;

[0043] Figure 4 This is a flowchart of step S1 of the method for evaluating the load capacity of a multi-hop dual-mode communication network according to an embodiment of the present invention;

[0044] Figure 5 This is a time slot diagram for dual-mode communication according to an embodiment of the present invention;

[0045] Figure 6 This is a flowchart of step S4 of the method for evaluating the load capacity of a multi-hop dual-mode communication network according to an embodiment of the present invention. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the present invention clearer, various exemplary embodiments described below will be referenced to the accompanying drawings, which form part of the exemplary embodiments, illustrating various exemplary embodiments that may be used to implement the present invention. Unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. It should be understood that they are merely examples of processes, methods, and apparatuses consistent with some aspects of the present invention disclosed as detailed in the appended claims, and other embodiments may be used, or structural and functional modifications may be made to the embodiments listed herein without departing from the scope and spirit of the present invention.

[0047] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," etc., indicate the orientation or positional relationship based on the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the referred element must have a specific orientation, or be constructed and operated in a specific orientation. The terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. The term "multiple" means two or more. The terms "connected" and "linked" should be interpreted broadly, for example, they can be fixed connections, detachable connections, integral connections, mechanical connections, electrical connections, communication connections, direct connections, indirect connections through an intermediate medium, and can be the internal connection of two elements or the interaction relationship between two elements. The term "and / or" includes any and all combinations of one or more of the related listed items. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0048] To illustrate the technical solution described in this invention, specific embodiments are described below, showing only the parts related to the embodiments of this invention.

[0049] Example 1:

[0050] like Figure 1 As shown, this invention provides a method for evaluating the load capacity of a multi-hop dual-mode communication network, comprising:

[0051] S1. Construct a multi-hop dual-mode communication network model, and establish the first objective function by maximizing the throughput of a single network in the multi-hop dual-mode network; the first objective function is constructed by introducing a resource allocation parameter that represents the normalized occupancy of the information flow;

[0052] S2. Based on the constraints of the half-duplex mechanism of communication equipment and the information flow transmission requirements on network resource allocation, construct the constraints of the first objective function;

[0053] S3. Introduce a satisfaction function to improve the first objective function, forming a second objective function; the constraints of the first objective function and the second objective function are the same.

[0054] S4. Based on the first objective function and the second objective function, a third objective function with integer constraints is obtained to optimize the throughput of multiple networks.

[0055] S5. The throughput under the optimal solution of the third objective function is taken as the load capacity of the multi-hop dual-mode communication network.

[0056] This embodiment introduces a resource allocation factor to analyze the throughput capacity of single and multiple networks in a power distribution IoT network that features multi-hop transmission, dual-mode transmission, and frequency hopping mechanisms. Because information flow transmission in this type of power distribution IoT requires multiple layers of relays, the necessary resources need to be allocated rationally when multiple information flows converge. Furthermore, considering the frequency hopping mechanism, dual-mode transmission, and the resource requirements of each information flow, the performance analysis method of this invention considers influencing factors more comprehensively, and the analysis results are more consistent with network characteristics, providing valuable reference for optimizing the performance of multiple networks.

[0057] The multi-hop dual-mode communication network model constructed in step S1 of this embodiment is as follows: Figure 2 As shown, this model includes multiple MNs (central control nodes), multiple RNs (routing aggregation nodes), and multiple ENs (end-point sensing nodes). ENs, acting as end-point sensing nodes, are distributed across various locations within the distribution area. They typically cannot communicate directly with MNs; instead, they need to collect multimodal sensing data from the environment and then relay it through multiple ENs or RNs before uploading the data to the MN. RNs, acting as routing aggregation nodes, are responsible for relaying data and do not generate new data themselves. MNs, acting as central control nodes, are responsible for receiving information from RNs and ENs and transmitting it back to the Internet. Therefore, this network model stipulates that multiple ENs and RNs can communicate via a dual-mode medium of power line carrier and radio frequency; there is no data loss during transmission, and delays such as access delay and propagation delay are ignored. A network formed by a single MN communicating with all its RNs and ENs via a dual-mode medium is a single network; a network with multiple MNs coexisting is a multi-network. MNs are referred to as the headend, and RNs and ENs are collectively referred to as the tailend.

[0058] To save on communication device costs for large-scale smart power distribution IoT, lower-performance communication modules are currently commonly used. Therefore, it is assumed that each node in the network is equipped with an omnidirectional single antenna, supporting only the processing of received or transmitted signals on a single channel at a time—a half-duplex communication mode. The transmit power of EN is P. EN The transmit power of RN is P. RN .

[0059] Due to the complex environment of power distribution areas, wireless signal obstruction is common. Therefore, it is assumed that frequency reuse exists in space within a single network, meaning that obstructed ends can communicate using the same frequency at the same time. Since power lines are connected in parallel, and according to measured data, when the ends use power line carrier communication, they compete for access channels in a specific frequency band more than 90% of the time. Therefore, it is stipulated that all devices using power line carrier communication share a single power line carrier channel, and that power line carrier communication does not interfere with wireless radio frequency communication.

[0060] This embodiment specifies that the network uses a time-division communication method, dividing a period of time into multiple time slots. Existing field networks employ a frequency-hopping mechanism that supports concurrent reporting, such as... Figure 3 As shown. This mechanism can resist multipath fading in wireless communication, avoid wireless interference, support concurrent event reporting, and improve the utilization of wireless channels. In single-channel mode, only one tail end can use the wireless channel for communication within a certain time period; the next tail end can only begin communication after the previous tail end has finished. With frequency hopping technology, when a tail end is communicating on a channel at a certain frequency, after a time slot, the entire network hops to another operating frequency band for communication. Tail ends that have not finished transmitting in the previous time slot can continue transmitting simultaneously. Here, a duration coefficient N is defined. p This is used to characterize the length of the time slot occupied by each tail transmission, such as Figure 3 In this system, node 1 has a persistence coefficient of 4, enabling concurrent reporting. Multiple networks collaboratively plan the frequency hopping sequence to ensure no interference between them. Therefore, within a single network, the frequency usage sequence is already defined, and the channels available in a given time slot within that network are already determined.

[0061] like Figure 4 As shown, step S1, establishing the first objective function, includes:

[0062] S11. Introduce a resource allocation parameter to represent the normalized occupancy of the information flow, and obtain the transmission rate of the information flow on each link in a single network transmission.

[0063] S12. Take the minimum transmission rate of an information stream as the end-to-end throughput rate.

[0064] S13. Maximize the sum of the throughput rates of all information flows within a single network as the first objective function.

[0065] In a communication network consisting of a single headend (i.e., a single network), there are multiple tailends and corresponding information streams that need to be uploaded by those tailends, multiple communication links, and multiple frequency band channels. In this embodiment, the set of all links within the field area network FAN Q is defined as L, the set of all tailends as T, the set of all information streams that need to be transmitted as I, and the set of all channels as F. Information streams generated by multiple tailends in the network are transmitted to the headend via multiple links and through the relaying action of tailends connected at multiple levels, undergoing multiple hops.

[0066] For such a time-division system, this embodiment assumes that the information flow transmits data by occupying a certain time slot on a single link. A resource allocation parameter is introduced. To represent the information flow I originating from the tail t t Normalized occupancy per unit time on link l and channel f, such as Figure 2The information stream shown in the FAN Q region occupies a certain amount of time-frequency resources on links l1, l2, and l3 for information transmission. Normalized occupancy refers to the ratio of occupied time resources to the total time resources on that channel. The range should be between 0 and 1. This embodiment assumes that the transmission rate C of all channels on link l is... l,f Correspondingly The sum of the products This is considered as the actual transmission rate of the information flow on link l. This invention assumes that the channel coefficients of power line carrier communication follow a log-normal distribution, and the channel coefficients of radio frequency communication follow a Rayleigh distribution. Therefore, the transmission rate on a certain channel can be written as:

[0067]

[0068] Among them, B f Indicates bandwidth, n b n represents the power spectral density of Gaussian white noise. i This represents the impulse noise power spectral density in a power line carrier channel. and E represents the fading gain of the power line carrier and the radio frequency channel, respectively. b P represents the average energy of power line carrier communication. EN / RN d is the transmit power of EN or RN, d is the length of link l, α is the channel fading coefficient of radio frequency communication, and G is the transmit power of EN or RN. RF This indicates the antenna gain.

[0069] Obviously, for a multi-hop transmission information stream I t Its end-to-end throughput rate depends on the minimum transmission rate on the link, so its throughput rate is:

[0070]

[0071] Therefore, the sum of the throughput rates of all information flows within a single network FAN Q can be obtained as follows:

[0072]

[0073] in, To normalize the occupancy, I t For information flow, l represents a link, f represents a channel; I represents the set of information flows; L represents the set of links; F represents the set of channels; C represents the set of channels. l,f The transmission rate is the sum of these throughput rates as the throughput within a single network FAN Q.

[0074] like Figure 5As shown, each individual colored block in the diagram is defined as a time-frequency resource block. According to the frequency hopping mechanism, the network can hop to another frequency after every time slot, thus generating a new resource block. The entire network possesses a certain number of resource blocks of different frequencies over a period of time. When a node's data packet is not fully transmitted within a single time slot, it can still continue transmission for a certain period of time. Figure 5 This is reflected in the fact that the length of a resource block is greater than the length of a single time slot. When orthogonal resource blocks overlap in time, concurrent reporting occurs within a single network. Here, the ratio of the duration of each communication resource block to the length of a single time slot is defined as N. p This is called the persistence coefficient, which characterizes the concurrent information transmission capability within a single network.

[0075] Within a single network, the frequency usage sequence is already defined, the channels available in a given time slot within the network are already determined, and the duration occupied by a frequency band per unit time is also fixed. Furthermore, due to frequency hopping and device half-duplex mechanisms, the allocation of time resources needs to meet certain rules. Therefore, the restrictions imposed on network resource allocation by the communication device half-duplex mechanism in step S2 include:

[0076] T1, transmission in the same-frequency interference link set L f Normalized occupancy of information flow in channel f The sum is less than the proportion of resource blocks occupied by the channel within the unit τ f ,Right now

[0077]

[0078] Among them, L f This refers to a set of links that experience co-channel interference, typically a set of links that are geographically close together. These links will experience co-channel interference and cannot transmit simultaneously. f This refers to the proportion of resource blocks occupied by channel f per unit time, determined by the frequency hopping sequence. This resource allocation rule is due to the limited number of resource blocks occupied by channel f per unit time when the frequency hopping sequence is determined.

[0079] T2. The number of time slots used for processing information streams (receiving and sending) at each tail end is less than 1, that is...

[0080]

[0081] Among them, L t Let be the set of links connected to the tail end t. This formula is used to describe the constraints imposed by the tail-end half-duplex mechanism.

[0082] N pWhen N is 1, the frequency hopping mode degenerates into a single-channel transmission mode. In this mode, there is no concurrent transmission in the network, and only one channel can transmit per time slot. However, when N... p A very high N indicates extremely strong network concurrency, allowing multiple channels to transmit in each time slot. p It cannot exceed the length of one frequency hopping sequence period, for Figure 3 In the case of N p If the value is greater than 5, it will cause crosstalk at the tail end of the preceding and following channels. p Excessive N can also cause interference between multiple networks, therefore the N of multiple networks p The sum does not exceed the number of frequency-hopping sub-channels.

[0083] Considering that power line carrier communication shares a single channel and operates on a specific frequency band in most cases, carrier communication can be regarded as a single-channel resource in the network and does not interfere with the radio frequency channel.

[0084] This embodiment defines the uplink load capacity of the network as follows: Each information stream has its own amount of arriving sensor signal data, which refers to the amount of power distribution operation and maintenance data collected by the tail-end sensors that needs to be uploaded. This data is generated at regular intervals and needs to be transmitted to the head-end within those intervals, typically every few minutes to tens of minutes. This data is transmitted to the head-end via multiple hops. The transmission rate at which the head-end finally effectively receives a particular tail-end data is called the uplink throughput rate of that tail-end. The sum of the throughput rates of all tail-ends is the network throughput rate, and the maximum network throughput rate is the uplink load capacity of the network.

[0085] The tail end transmits information through multiple hops, with each hop having a corresponding transmission rate. The hop with the lowest rate is considered the throughput rate of that tail end. Clearly, without considering packet loss, equal transmission rates on each hop are necessary to ensure optimal network resource utilization. For the throughput rate of a single network, due to the half-duplex mechanism, the head end can only receive data from one tail end on one channel at a time. Therefore, among all tail ends directly connected to the head end, the transmission rate of the tail end with the best channel represents the upper limit of the network throughput rate, which is also the network's uplink load capacity. When the network concentrates all resources on these tail ends, the network throughput rate is maximized. However, this is not the desired result of this invention. But as an inspiration, to improve the throughput rate, one can only consider allowing concurrent reception at the head end or increasing the transmission rate at the tail ends directly connected to the head end, i.e., improving the channel environment or increasing transmission bandwidth and transmit power.

[0086] To avoid the resource allocation problem mentioned above, the transmission rate of the information flow is constrained. Each information flow is defined as having certain data transmission requirements, and the amount of data that different information flows need to transmit is defined as {A}. 1 A 2 A 3…}. The transmission of information streams is time-limited, meaning that the information stream needs to be transmitted within [T] within a single link. min ,T max Successful transmission within [the specified range] indicates that the transmission rate of each information stream on the link ranges from [the specified range] to [the specified range]. Where R th This represents the upper limit of the transmission rate of a single information flow on the link. Based on the above analysis, the limitations imposed on network resource allocation by the information flow transmission demand in step S2 include:

[0087] T3. The transmission rate of a single information stream is equal across multiple links, that is...

[0088]

[0089] in For information flow I t The set of links along the path;

[0090] T4, the range of transmission rates is Right now

[0091]

[0092] Among them, A t ={A 1 A 2 A 3 …} to meet the transmission needs of different information flows; [T min ,T max [R] represents the time interval within which an information stream needs to be successfully transmitted within a single link; th This represents the upper limit of the transmission rate of a single information stream on the link.

[0093] The resource allocation parameters introduced in this method To normalize resource usage, therefore The parameters are continuously varying between 0 and 1. Due to the three-phase polling access limitation of power line carrier communication, the normalized occupancy of the power line carrier channel should not exceed 1 / 3. Simultaneously, if an information flow does not pass through a certain link, the resource occupancy of that information flow on that link is always 0. Thus, constraints 5 and 6 are derived:

[0094] T5, the normalized occupancy varies continuously between 0 and 1, and the normalized occupancy in the power line carrier channel does not exceed 1 / 3, that is...

[0095]

[0096] T6. The normalized occupancy of information flow on links that it does not pass through is always 0, that is...

[0097]

[0098] Combining all constraints, the throughput in FAN Q can be expressed as a function of... Optimization problem:

[0099]

[0100] The planning problem is solved with the objective function of maximizing the throughput rate of a single network. The optimal solution of the first objective function P1 can be used to represent the load capacity of a single network. However, this resource allocation method is unbalanced, specifically manifested in the fact that the information flow throughput rate of the higher-level tail end is higher, while the information flow throughput rate of the lower-level tail end is generally lower.

[0101] Therefore, a resource allocation method based on a satisfaction function is proposed, which can make network resource allocation more even. Satisfaction is used to represent the throughput rate allocated to information flows in relation to their transmission requirements. The higher the ratio of the allocated throughput rate to the transmission demand, the more "satisfactory" the result. This ratio is used as the input to the satisfaction function. The satisfaction function is defined as a monotonically increasing form with a sharply decreasing first derivative, ensuring that the ratio of the allocated throughput rate to the transmission demand for each information stream is similar. Therefore, the satisfaction function is set as: S(x) = -e -(x-1) , where x is the independent variable.

[0102] Therefore, step S3 introduces a satisfaction function to improve the first objective function. Specifically, the ratio of the first objective function to the transmission demand of different information flows is used as the independent variable input into the satisfaction function to obtain the second objective function. Combined with the previous constraints, a new goal programming problem is formed:

[0103]

[0104] To solve the problem with the first objective function P1, constraint C3 can be used to rewrite the first objective function P1 as follows:

[0105]

[0106] Wherein, L is defined 1 This is the set of links at the one-hop access headend. Joint constraint C5 applies only to information flow at the corresponding link. By optimization, problem P1 can be transformed into a linear programming problem. Introducing slack variables into P1 makes it easy to see that the constraint dimension of this linear programming problem is always less than the dimension of the variables, thus indicating the existence of an optimal solution. The second objective function, P2, is handled in the same way. It is a linear combination of concave functions with a non-empty compact set feasible region, therefore also possessing an optimal solution. At the same arrival rate, the network throughput obtained under problem P2 is no greater than that obtained under problem P1, but the network resource allocation scheme obtained under problem P2 is more even. The optimal solution of the second objective function P2 can be represented as the load capacity of a single network under balanced network resource allocation.

[0107] Given the network topology, frequency hopping sequence, average reachability of each channel, and data stream transmission requirements generated by each tail end, the uplink load capacity of a single network consisting of a single headend can be obtained by solving the above planning problem under two resource allocation scenarios.

[0108] The entire field area network consists of multiple headends forming a network, and the load capacity of these multiple networks can be considered as the sum of the load capacities of the multiple headends. To avoid the impact of crosstalk between multiple channels when multiple networks are running simultaneously, current networks employ a multi-network operation channel avoidance strategy, namely a frequency hopping mechanism. This embodiment describes this mechanism using a duration coefficient N. p This is used to characterize the features of this frequency hopping mechanism. For a single network with different topologies, routing, and channel rates, its load capacity varies with N. p The throughput increases with the improvement of the network, eventually tending to a constant value. The sum of the throughputs of multiple single networks is used as the objective function, N. p As decision variables, this forms an optimization problem concerning the throughput of multiple networks, the optimal solution of which is the N that the corresponding network should be allocated. p .

[0109] However, the single network throughput R Q With N p An analytical solution cannot be obtained. Therefore, the discrete throughput and N obtained under the above P1 and P2 problems are used to solve the problem. p The discrete relationship transforms the optimization problem of discrete variables into an optimization problem with integer constraints.

[0110] Thus, we can obtain the following: Figure 6 Step S4 shown includes:

[0111] S41. Solve for the single-network throughput and duration coefficient N based on the first objective function and the second objective function. p The discrete relationship; where the duration coefficient N p The length of the time slot occupied for each tail transmission;

[0112] S42. The sum of all single-network throughputs is taken as the multi-network throughput;

[0113] S43. Introducing indicator variables Based on the discrete relationship between single-network throughput and persistence coefficient, a third objective function representing the throughput of multiple networks is obtained. Furthermore, constraints are imposed to construct the third objective function to avoid mutual interference between individual networks.

[0114] The resulting target programming problem regarding multi-network throughput is as follows:

[0115]

[0116] Where H is the set of all individual networks in the multi-network scheme, Q is a single network, and N... channel The number of frequency hopping sub-channels is the number of sub-channels. For a single network Q in a certain N p The throughput is derived from problems P1 and P2. D is N. p The range of values ​​for , As an indicator variable taking the value 0 or 1, single networks that may cause co-channel interference are written into the set H. c middle, Set H c A single network is typically a spatially adjacent network, while a multi-network can contain multiple Hs. c .

[0117] The third objective function is to correlate the throughput of different single networks Q with N. p The relationships are divided into multiple groups, and only one corresponding N is taken from each group. p throughput The sum of the throughput of all groups equals the throughput of the multi-network, thus forming the third objective function and its corresponding constraints C7 and C8. Furthermore, since set H... c N of all single networks p The sum must be less than the number of frequency-hopping sub-channels to avoid mutual interference between individual networks, thus forming constraint C9.

[0118] Given a frequency-hopping sequence, resources within a single network are allocated over a fixed-width frequency-hopping sub-channel in the time dimension. The total load capacity across multiple networks depends on the design of the frequency-hopping sequence itself. Since the total spectrum resources are finite, dividing the total bandwidth into multiple different frequency-hopping sub-channels and the proportion of each channel in the sequence affects the load capacity of both single and multiple networks. However, with a limited total spectrum, the more sub-channels are divided, the more the load capacity of a single network monotonically decreases, as shown by theoretical analysis and simulation results. But in the case of multiple networks, the load capacity of N networks without interference... pThe sum increases with the number of frequency-hopping sub-channels, which can improve the network's concurrency capability and thus enhance the load capacity of multiple networks. Therefore, the load capacity of multiple networks can potentially increase with the increase of frequency-hopping sub-channels. Thus, this problem can be studied using a third objective function to find the number of frequency-hopping sub-channels that maximizes the load capacity of multiple networks.

[0119] The method proposed in this embodiment analyzes the throughput capacity of single and multiple networks in a power distribution IoT network that employs multi-hop transmission, dual-mode transmission, and frequency hopping mechanisms by introducing a resource allocation factor. Because information flow transmission in this type of power distribution IoT requires multiple layers of relays, the necessary resources need to be rationally allocated when multiple information flows converge. Furthermore, considering the frequency hopping mechanism, dual-mode transmission, and the resource requirements of each information flow, the performance analysis method of this invention considers influencing factors more comprehensively, and the analysis results are more consistent with network characteristics, providing valuable reference for optimizing the performance of multiple networks.

[0120] The embodiment is merely a specific example and does not indicate that this is the only way to implement the present invention.

[0121] The above description is merely a preferred embodiment of the present invention. Those skilled in the art will understand that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the present invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A method for evaluating the load capacity of a multi-hop dual-mode communication network, characterized in that, include: S1. Construct a multi-hop dual-mode communication network model, and establish a first objective function based on maximizing the throughput of a single network in the multi-hop dual-mode network; S2. Construct the constraints of the first objective function based on the half-duplex mechanism of communication equipment and the constraints of information flow transmission requirements on network resource allocation; S3. Introduce a satisfaction function to improve the first objective function, forming a second objective function; S4. Based on the first objective function and the second objective function, obtain the third objective function with integer constraints that optimizes the throughput of multiple networks; S5. The throughput under the optimal solution of the third objective function is taken as the load capacity of the multi-hop dual-mode communication network; Step S4 includes: S41. Solve the discrete relationship between single network throughput and duration coefficient according to the first objective function and the second objective function; wherein, the duration coefficient is the time slot length occupied by each tail transmission; S42. The sum of all the single network throughputs is taken as the multi-network throughput; S43. Introduce indicator variables and obtain the third objective function representing the multi-network throughput based on the discrete relationship between the single network throughput and the persistence coefficient.

2. The method for evaluating the load capacity of a multi-hop dual-mode communication network according to claim 1, characterized in that, Step S1, establishing the first objective function, includes: S11. Introduce a resource allocation parameter to represent the normalized occupancy of the information flow, and obtain the transmission rate of the information flow on each link in a single network transmission. S12. The minimum value of the transmission rate of one of the information streams is taken as the end-to-end throughput rate. S13. Maximize the sum of the throughput rates of all information flows within a single network as the first objective function.

3. The method for evaluating the load capacity of a multi-hop dual-mode communication network according to claim 2, characterized in that, The sum of the throughput rates is: in, The normalized occupancy, For the information flow, l For the link, f For channels; I A collection of information flows; L For a set of links; F For a set of channels; The transmission rate is [value].

4. The method for evaluating the load capacity of a multi-hop dual-mode communication network according to claim 2, characterized in that, The limitations of the half-duplex mechanism of the communication device in step S2 on network resource allocation include: T1. The sum of the normalized occupancy of the information flow transmitted in the same frequency interference link set on the channel is less than the proportion of resource blocks occupied by the channel within the unit; T2. The number of time slots used for processing information streams at each tail end is less than 1.

5. The method for evaluating the load capacity of a multi-hop dual-mode communication network according to claim 2, characterized in that, The limitations on network resource allocation imposed by the information flow transmission requirements in step S2 include: T3. The transmission rate of a single information stream is equal across multiple links; T4, the range of the transmission rate is: ,in, To meet the transmission requirements of the different information streams; The time interval within which the information stream needs to be successfully transmitted within a single link; This represents the upper limit of the transmission rate of a single information stream on the link; T5. The normalized occupancy varies continuously between 0 and 1, and the normalized occupancy in the power line carrier channel does not exceed 1 / 3. T6. The normalized occupancy of the information flow on links that it does not pass through is always 0.

6. The method for evaluating the load capacity of a multi-hop dual-mode communication network according to claim 1, characterized in that, Step S3 includes: inputting the first objective function into the satisfaction function as the ratio of the amount of data to be transmitted for different information streams, thereby obtaining the second objective function.

7. The method for evaluating the load capacity of a multi-hop dual-mode communication network according to claim 6, characterized in that, The satisfaction function is: ,in, x is the independent variable.

8. The method for evaluating the load capacity of a multi-hop dual-mode communication network according to claim 1, characterized in that, To avoid mutual interference between the individual networks, the third objective function is constructed under the constraint condition.

9. The method for evaluating the load capacity of a multi-hop dual-mode communication network according to claim 1, characterized in that, The optimal solution of the first objective function represents the load capacity of the single network; the optimal solution of the second objective function represents the load capacity of the single network under balanced network resource allocation.

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