Self-organizing network multi-frequency-point synchronous control method

Abstract

The invention relates to the field of wireless communication and multi-frequency-point synchronous control, in particular to a self-organizing network multi-frequency-point synchronous control method, which comprises the following steps of: S1, configuring a wide-spectrum working frequency band for a self-organizing network, setting N frequency points and setting a main frequency; s2, the master node broadcasts a synchronization frame containing synchronization information through N frequency points; s3, each node receives a synchronization frame containing synchronization information sent by an upper-level synchronization node and carries out synchronization; s4, after the synchronization of the nodes is completed, forwarding the synchronization frame containing the synchronization information according to a certain probability, and returning to the step S3; s5, the steps S2 to S4 are periodically repeated, and periodic synchronization of all nodes in the self-organizing network is completed; s6, each node reserves a service time slot with the target node according to the service driving information, and transmits information on the main frequency based on the reserved time slot; and S7, updating the frequency point and the main frequency according to the scene change and the electromagnetic environment. According to the invention, the reliability of the self-organizing network and the adaptability to complex environments are improved.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication and multi-frequency synchronization control, and particularly to a multi-frequency synchronization control method for an ad hoc network. Background Art

[0002] An ad hoc network (hereinafter referred to as an ad hoc network) is an important networking form in the field of wireless communication. It has functions such as wireless packet "store-and-forward" and multi-hop relay, and can realize the construction of a centerless network, network self-organization, and transmission path self-repair. The networking method is flexible and plays an important role in various complex application scenarios.

[0003] However, due to frequency conflicts and complex electromagnetic environments, ad hoc networks face various spectrum constraints or uncertain electromagnetic interference, which affects the performance of ad hoc networks. How to ensure the reliability of the network in an environment where the signal quality frequently deteriorates? One of the key issues is how to make the ad hoc network synchronization control adapt to various challenges and ensure its reliability.

[0004] There are two traditional methods. One is to externally connect a clock synchronization source (such as satellite time synchronization) to each node of the ad hoc network, and the other is to use the ad hoc network self-synchronization technology (protocol) to achieve synchronization of each node. Both methods have relatively wide applications. The former has high synchronization accuracy and can simplify the design of the ad hoc network protocol, but it requires nodes to be configured with corresponding satellite synchronization time synchronization radio frequency components and is restricted in some shielding scenarios. The latter uses a protocol to achieve self-synchronization of each node, which will increase the complexity of the ad hoc network networking protocol, but also enhances the flexibility of network applications and the adaptability to complex scenarios.

[0005] Among them, the traditional design of the self-synchronization protocol between each node of the ad hoc network is further divided into two categories: one is in-band synchronization control, that is, the service information transmission and synchronization control share the same channel; the other is out-of-band synchronization control, which isolates important control channel information (such as synchronization) in an independent and robust wireless link to achieve separation of the control plane and the data plane. Even in the case of loss of the data channel, the reliability of the network can still be ensured. Nevertheless, these traditional ad hoc network synchronization controls are all fixed configuration modes, and the adjustment of the service channel is supported by a fixed control channel, but the vulnerability of the synchronization control itself is still the bottleneck of network reliability.

[0006] Therefore, how to design an ad hoc network that enhances the reliability of the network and the adaptability to complex environments is a technical problem that urgently needs to be solved. Summary of the Invention

[0007] In view of the deficiencies of the above-mentioned prior art, the technical problem to be solved by the present invention is: how to provide a multi-frequency synchronization control method for an ad hoc network, configure the ad hoc network into a wide-spectrum framework, disperse and select multiple frequency points within the wide spectrum range, and update the frequency points according to the scenario changes and the electromagnetic environment, so as to improve the reliability of the ad hoc network and its adaptability to complex environments.

[0008] To solve the above technical problem, the present invention adopts the following technical solutions:

[0009] A multi-frequency synchronization control method for an ad hoc network, comprising:

[0010] S1: Configure a wide-spectrum operating frequency band for the ad hoc network, set N frequency points within the operating frequency band and determine a main frequency;

[0011] S2: The master node broadcasts a synchronization frame containing synchronization information through N frequency points;

[0012] S3: Each node receives the synchronization frame containing synchronization information sent by its upper-level synchronization node and performs synchronization; the upper-level synchronization node of the one-hop node of the master node is the master node;

[0013] S4: After the node completes synchronization, forward the synchronization frame containing synchronization information with a certain probability and return to step S3;

[0014] S5: Periodically repeat steps S2 to S4 to complete the periodic synchronization of all nodes in the ad hoc network;

[0015] S6: Each node makes a reservation for the service time slot with the target node according to the service-driven information and transmits information based on the reserved time slot on the main frequency;

[0016] S7: Update the frequency points and the main frequency of the operating frequency band according to the scenario changes and the electromagnetic environment.

[0017] Preferably, in step S2, the synchronization frame sent by the master node includes a scanning time slot, a master node synchronization time slot, and several groups of corresponding access time slots and synchronization time slots;

[0018] The master node broadcasts its synchronization information in the master node synchronization time slot;

[0019] One access time slot includes several access cycles;

[0020] One access cycle includes three time segments: request, response, and confirmation.

[0021] Preferably, in step S3, synchronization is performed through the following steps:

[0022] S301: After receiving the synchronization frame sent by its upper-level synchronization node, each node establishes one-way synchronization with its upper-level synchronization node; wherein all nodes establishing one-way synchronization are source ID nodes, and the corresponding upper-level synchronization node is the target ID node;

[0023] S302: Each source ID node initiates an access request to the target ID node based on a certain probability, and competes for access in several access cycles of the corresponding access time slot;

[0024] When the source ID node successfully competes for access in a certain access period of the access time slot, the subsequent access period of the access time slot is no longer used, and the source ID node occupies the synchronization time slot immediately following the access time slot;

[0025] S303: After receiving the response message from the target ID node, the source ID node that successfully competes for access performs bidirectional synchronization with the target ID node.

[0026] Preferably, in step S302, the processing step of contention access includes:

[0027] S3021: In the request time segment of the current access cycle, the source ID node initiates a forwarding synchronization request message to the target ID node;

[0028] S3022: After receiving the forwarding synchronization request message, the target ID node determines whether a collision is detected; if so, execute step S3023; otherwise, reply a response message to the source ID node in the response time segment and execute S3024;

[0029] S3023: The target ID node does not make any response in the response time segment, and the source ID node does not receive a response in the response time segment, that is, it is considered that a collision occurs with other source ID nodes, and waits for the competition of the subsequent access cycle;

[0030] S3024: After receiving the response message, the source ID node confirms that the contention access is successful and occupies the synchronization time slot immediately following the access time slot; at the same time, the response message will inform all other source ID nodes that are competing with the current source ID node that the corresponding synchronization time slots have been occupied;

[0031] S3025: The source ID node sends a forwarding synchronization confirmation message in the confirmation time segment, so that the one-hop node of the source ID node is informed that the subsequent time slot is occupied.

[0032] Preferably, in step S303, two-way synchronization is performed through the following steps:

[0033] S3031: record the sending time of the source ID node forwarding the synchronization request message as T1;

[0034] S3032: record the receiving time of the source ID node response message as T2;

[0035] S3033: define the message processing time of the source ID node in a successful contention access in the request time segment and the response time segment as T3;

[0036] S3034: Calculate the propagation delay ΔT using the following formula:

[0037]

[0038] S3035: The source ID node establishes bidirectional synchronization with the target ID node, i.e., the previous-level synchronization node, by adjusting the propagation delay ΔT.

[0039] Preferably, in step S3, the following broadcast or forwarding rules are set:

[0040] 1) The master node forwards the previous synchronization frame for more than 3 hops before broadcasting the next synchronization frame;

[0041] 2) When the previous synchronization frame is broadcast to the last time slot of the current synchronization frame, the node receiving the synchronization frame continues to compete for access in the access time slot of the next synchronization frame;

[0042] 3) When a node needs to forward a synchronization frame, and the previous synchronization frame has not been successfully forwarded, and the next latest synchronization frame is received, only the latest received synchronization frame is forwarded.

[0043] Preferably, in step S6, the processing steps of service time slot reservation include:

[0044] S601: Each node monitors one-hop information transmission and maintains a list of idle time slots;

[0045] S602: When a node is driven by upper-layer services and needs to reserve a service time slot to support information transmission, it is a source ID node; the source ID node selects a nearby idle time slot for competition reservation; the time slot is divided into several reservation cycles, and the source ID node tries to compete from the first reservation cycle;

[0046] S603: The source ID node learns the destination ID node to be sent according to the service driving information, and sends a time slot request message to the destination ID node;

[0047] S604: The destination ID node receives the time slot request message and determines whether a collision occurs: if a collision occurs, execute step S605; otherwise, execute step S606;

[0048] S605: The destination ID node does not reply to the task, and the source ID node makes another reservation in a subsequent reservation period; when the source ID node detects that another node has made a successful reservation in a reservation period of the current time slot, the time slot should be changed to make another reservation;

[0049] S606: The destination ID node replies with a time slot response message; the time slot response message includes available time slots, where the available time slot information is obtained by the destination ID node according to the received time slot information to be applied for, and by comparing it with its own idle time slot information table.

[0050] S607: The source ID node receives the time slot response message replied by the destination ID node, completes the reservation of the corresponding time slot with the destination ID node, and sends a time slot confirmation message; through the time slot confirmation message, the nodes within one-hop range of the source ID node and the destination ID node respectively learn the message that the reserved time slot is occupied, so that these nodes can update the idle time slot list they maintain.

[0051] S608: The source ID node transmits information on the main frequency based on the reserved time slot.

[0052] Preferably, in step S606, the generation of available time slots includes the following three cases:

[0053] 1) If the number of identical idle time slots in the idle time slot lists of both the source ID node and the destination ID node is greater than the number of time slots to be applied for, the destination ID node randomly selects time slots that meet the quantity requirements from them as available time slots.

[0054] 2) If the number of identical idle time slots in the idle time slot lists of both the source ID node and the destination ID node is equal to the number of time slots to be applied for, these idle time slots are directly used as available time slots.

[0055] 3) If the number of identical idle time slots in the idle time slot lists of both the source ID node and the destination ID node is less than the number of time slots to be applied for, the destination ID node selects all the identical idle time slots from them as available time slots, providing time slot resources for service (information transmission) degradation.

[0056] Preferably, in step S7, the frequency point adjustment is performed through the following steps:

[0057] S701: The master node scans and senses the spectrum in the scanning time slot, selects the frequency points with the best quality in the frequency section according to the section division to form a frequency group, and broadcasts a synchronization announcement message including the frequency group information synchronously for multiple frequency points.

[0058] S702: While receiving the synchronization announcement message, each node monitors the quality of each frequency point in the frequency group, divides the frequency point quality into multiple quality levels, and attaches the frequency group quality level information to the routing control message, and periodically converges to the master node.

[0059] S703: The master node decides on a frequency point adjustment plan based on the frequency group quality level information monitored by each node: In a frequency group, when a certain frequency point is available and the number of nodes detecting the availability of this frequency point is the largest, this frequency point is configured as the primary frequency; when there are two or more frequency points with the same and largest number of available nodes, the one with a higher average quality level after being detected by all nodes is selected as the primary frequency;

[0060] When one of the following two situations occurs, the master node needs to rescan the frequency points to update the frequency group:

[0061] 1) The number of nodes detecting the availability of the primary frequency is lower than a preset threshold;

[0062] 2) The number of nodes detecting the availability of more than half of the frequency points in the frequency group is lower than a preset threshold;

[0063] S704: The master node synchronizes the adjustment information in the new frequency group announcement.

[0064] Preferably, in step S702, it specifically includes the following steps:

[0065] S7021: Each node monitors the one-hop information transmission and maintains a list of idle time slots;

[0066] S7022: When driven by the upper-layer protocol, the node needs to reserve a time slot, and this node is the source ID node;

[0067] S7023: The source ID node selects a nearby idle time slot for competitive reservation; The time slot is divided into several reservation cycles, and the node starts to attempt competition from the first reservation cycle;

[0068] S7024: The source ID node first sends a routing time slot request message;

[0069] After the one-hop node of the source ID node receives it, if there is no collision and this idle time slot is available, it does not make any response; If the source ID node does not receive any response during the reporting phase, it indicates that this time slot can be reserved, and then it performs time slot reservation and sends a confirmation message during the confirmation phase. All one-hop nodes of the source ID node send response messages during the response phase;

[0070] When a reservation cycle fails in reservation, it transfers to the subsequent reservation cycle for competition; If it is detected that another node has successfully reserved in a certain reservation cycle of this time slot first, a new time slot is selected for reservation.

[0071] S7026: The source ID node, all its one-hop nodes, and the neighbor nodes of the one-hop nodes all learn that the reserved time slot is occupied and update their idle time slot lists;

[0072] S7027: The source ID node sends a routing control message on the reserved time slot.

[0073] Compared with the prior art, the multi-frequency point synchronization control method for the ad-hoc network in the present invention has the following beneficial effects:

[0074] The present invention configures the working frequency band of the ad-hoc network as a wide-spectrum framework. Since frequency conflict and wireless interference are the key factors affecting the reliability of the ad-hoc network link, and spectrum resource redundancy is the core to cope with electromagnetic interference. In some complex application scenarios, although there is the influence of interference, the situation that affects the entire spectrum or wide spectrum is relatively rare. Therefore, the wide-spectrum framework of the present invention provides spectrum resource gaps for reliable communication, thereby improving the stability of the ad-hoc network.

[0075] The present invention dispersedly selects multiple frequency points (corresponding to multiple channels) within the wide-spectrum range, and adopts synchronous control frame frequency conversion transmission to support multi-frequency point network access synchronization, effectively coping with the network access synchronization obstacle caused by the blocking of some frequency points, and significantly enhancing the reliability of the transmission of the synchronous control information of the ad-hoc network.

[0076] Based on the dispersed selection of multiple frequency points on the wide spectrum, the present invention updates the frequency points and main frequencies of the working frequency band according to the scene change and the influence of the electromagnetic environment, enabling adaptation to the scene change and the electromagnetic environment, and updating the multi-frequency points for synchronous control and the single frequency point for service transmission; and adopts a combination of multi-node distributed detection and temporary centralized decision-making to construct a multi-frequency point adaptation mechanism, realizing all dynamic changes of the ad-hoc network synchronous control and service transmission, thereby enhancing the adaptability of the ad-hoc network to complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] In order to make the objectives, technical solutions and advantages of the invention clearer, the present invention will be further described in detail below with reference to the drawings, where:

[0078] Figure 1 It is a schematic diagram of setting N frequency points within the working frequency band.

[0079] Figure 2 It is a schematic diagram of the logical framework of the multi-frequency point transmission mechanism.

[0080] Figure 3 It is a schematic diagram of the logical framework of the multi-frequency point adaptation mechanism.

[0081] Figure 4 It is a schematic diagram of the logical framework of the routing message reservation mechanism.

[0082] Figure 5 It is a schematic diagram of the synchronous frame.

[0083] Figure 6 It is a schematic diagram of the logical framework of the access period.

[0084] Figure 7It is a flowchart for forwarding synchronization information with a certain probability.

[0085] Figure 8 It is a schematic diagram of the logical framework of the information transmission reservation mechanism. Detailed implementation manners

[0086] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part rather than all of the embodiments of the present invention. Components of the embodiments of the present invention generally described and illustrated in the drawings herein can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0087] It should be noted that like reference numerals and letters denote like items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive distinction and should not be construed as indicating or implying relative importance. In addition, terms such as "horizontal" and "vertical" do not mean that the components are required to be absolutely horizontal or hanging, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined. In the description of the present invention, it should also be noted that unless otherwise clearly defined and limited, the terms "set", "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0088] The following is a further detailed description through specific implementation manners:

[0089] Embodiment:

[0090] This embodiment discloses a multi-frequency point synchronization control method for an ad hoc network.

[0091] A multi-frequency point synchronization control method for an ad hoc network includes:

[0092] S1: Configure a wide-spectrum working frequency band for the ad hoc network, set N frequency points within the working frequency band and determine a main frequency.

[0093] S2: The master node broadcasts a synchronization frame containing synchronization information through N frequency points.

[0094] S3: Each node receives the synchronization frame containing synchronization information sent by its upper-level synchronization node and performs synchronization.

[0095] During initial network access synchronization, the upper-level synchronization node of the one-hop node of the master node is the master node.

[0096] S4: After the node completes synchronization, it forwards the synchronization frame containing synchronization information with a certain probability and returns to step S3.

[0097] S5: Periodically repeat steps S2 to S4 to complete the periodic synchronization of all nodes in the ad hoc network.

[0098] S6: Each node makes a reservation for the service time slot with the target node according to the service-driven information and transmits information based on the reserved time slot on the main frequency.

[0099] S7: Update the frequency points and the main frequency of the working frequency band according to the scenario change and the electromagnetic environment.

[0100] The present invention configures the working frequency band of the ad hoc network as a wide-spectrum framework. Since frequency conflict and wireless interference are the key factors affecting the reliability of the ad hoc network link, and spectrum resource redundancy is the core to cope with electromagnetic interference. In some complex application scenarios, although there is an impact of interference, the situation that affects the entire spectrum or wide spectrum is relatively rare. Therefore, the wide-spectrum framework of the present invention provides a spectrum resource gap for reliable communication, thereby improving the stability of the ad hoc network.

[0101] The present invention dispersedly selects multiple frequency points (corresponding to multiple channels) within the wide-spectrum range and adopts frequency-variable transmission of the synchronization control frame to support multi-frequency point network access synchronization, effectively coping with the network access synchronization obstacle caused by the blocking of some frequency points and significantly enhancing the reliability of the transmission of the synchronization control information of the ad hoc network.

[0102] Based on the selection of multiple frequency points dispersed in a wide spectrum, the present invention updates the frequency points and the main frequency of the working frequency band according to the scene change and the electromagnetic environment, so as to adapt to the scene change and the electromagnetic environment, and update the multi-frequency points of synchronous control and the single frequency point of service transmission; and adopts a combination of multi-node distributed detection and temporary centralized decision-making to construct a multi-frequency point adaptation mechanism, realizing all dynamic changes in self-organizing network synchronous control and service transmission, thereby enhancing the adaptability of the self-organizing network to complex environments.

[0103] To better introduce the technical solution of the present invention, this embodiment will be described through the following several parts.

[0104] I. Basic description

[0105] 1. The so-called wide spectrum, described from a relative perspective, is much wider than the current traditional self-organizing network working frequency band. From an absolute perspective, it can be considered that the frequency band range is above the GHz magnitude (such as 300 MHz - 2 GHz).

[0106] 2. Each node of the self-organizing network has a spectrum scanning function within the working frequency band range, and a dedicated scanning time slot is set in the MAC layer frame structure.

[0107] 3. The self-organizing network will determine the central node through pre-designation or multi-node temporary election negotiation. The central node can be temporarily changed.

[0108] 4. Assume that the blocking situations of multiple frequency points dispersed in the wide spectrum range are mainly: simultaneous blocking of some frequency points or full-frequency blocking by time sharing.

[0109] 5. A node can only be in one of the four states of sending, receiving, idle, and scanning at the same time resource.

[0110] 6. Each node has a unique identification ID.

[0111] 7. When two or more (including) packets arrive at the same node in the same time resource, the node detects a collision and all packets are lost.

[0112] II. Basic technical framework of wide-spectrum frequency conversion

[0113] 1. Wide-spectrum multi-frequency point configuration

[0114] As Figure 1 shown, N frequency points are dispersed and set in the working frequency band (it is recommended that N = 4), and the frequency points are as discrete as possible.

[0115] The interval setting method can be adopted to divide the entire working frequency band into N equal-interval frequency band intervals, and then select one frequency point in each section, and one of them is set as the main frequency point.

[0116] 2. Multi-frequency point transmission mechanism

[0117] In this embodiment, the synchronization announcement should be broadcast in sequence by frequency conversion according to N preset frequency points. One of the N frequency points is the main frequency, and the main frequency is also the current service transmission frequency. Each node first camps on the main frequency point during network access synchronization. Under normal interference-free conditions, it can receive the same-frequency frame on the main frequency to establish synchronization. If there is interference on the main frequency, and the node still cannot synchronize after camping for a certain period of time, the node will adjust to the subsequent frequency points to camp, and so on,... It can find a passable frequency point in the synchronization announcements of multiple frequency points to establish synchronization. As Figure 2 shown, when N = 4, the multi-frequency point transmission mechanism is demonstrated.

[0118] 3. Multi-frequency point adaptation mechanism

[0119] In this embodiment, a multi-frequency point adaptation mechanism of "main node sensing and frequency selection - each node monitoring and reporting - main node decision-making and adjustment - multi-frequency point synchronization announcement" is established, which has the characteristics of high efficiency and high reliability. The main node in the network scans and senses, determines the frequency group according to the section division and frequency point quality, and performs multi-frequency point broadcasting (including frequency group information). While each node receives the synchronization announcement information, it monitors the quality of each frequency point in the frequency group, and converges the monitoring reports to the main node. The main node makes a decision to adjust the frequency point scheme according to the frequency point quality information monitored by each node, and adjusts the information in the synchronization announcement of the new frequency group. Generally, other nodes can obtain the adjustment information by maintaining the unchanged frequency point, and in severe cases, they can also obtain the adjustment information through section scanning. The multi-frequency point adaptation mechanism is as Figure 3 shown.

[0120] Specifically, the frequency point adjustment is carried out through the following steps:

[0121] S701: The main node scans and senses the spectrum during the scanning time slot, selects the frequency points with the best quality in the frequency section according to the section division to form a frequency group (such as F1 - F2 - F3 - F4), and performs multi-frequency point synchronization broadcasting of the synchronization announcement information including the frequency group information;

[0122] There are two points to note for each node when receiving the synchronization announcement information: one is that the frequency group needs to be preset during initial operation; the other is that the subsequent frequency group is obtained by the network main node combining multiple scanning time slots.

[0123] S702: While each node receives the synchronization announcement information, it monitors the quality of each frequency point in the frequency group, divides the frequency point quality into multiple quality levels (such as 6 levels), and attaches the frequency group quality level information to the routing control message (or sets a special frequency group quality report message), and converges it to the main node regularly;

[0124] S703: The master node decides on a frequency point adjustment plan based on the frequency group quality level information monitored by each node: In a frequency group, when a certain frequency point is available (when it exceeds a certain quality level, for example, when the quality level is 6, frequencies 1 - 5 are available and 6 is not), and the number of nodes detecting the availability of this frequency point is the largest, then this frequency point is configured as the primary frequency; when there are two or more frequency points with the same and largest number of available nodes, the one with a higher average quality level after being detected by all nodes is selected as the primary frequency;

[0125] When one of the following two situations occurs, the master node needs to rescan the frequency points to update the frequency group:

[0126] 1) The number of nodes detecting the availability of the primary frequency is lower than a preset threshold, such as 80%;

[0127] 2) The number of nodes detecting the availability of more than half of the frequency points in the frequency group is lower than a preset threshold, such as 25%;

[0128] S704: The master node synchronizes the adjustment information in the new frequency group announcement.

[0129] Generally, other nodes can obtain the adjustment information by maintaining the unchanged frequency point broadcast announcement. In extreme cases where the entire frequency group changes, the nodes can also obtain the adjustment information through sector scanning.

[0130] The multi - frequency point adjustment mechanism of the present invention is applicable to the ad - hoc network scenario, has good adaptability, and has advantages such as high feasibility and high multi - node negotiation and decision - making efficiency.

[0131] Specifically, for the dedicated frequency group quality report message, directional aggregation is adopted and it is transmitted based on a specific destination ID, and its information transmission resources are processed according to service time slot reservation; for the routing control message mode, a routing message reservation mechanism should also be solved, such as Figure 4 As shown, it specifically includes the following steps:

[0132] S7021: Each node monitors the one - hop information transmission and maintains an idle time slot list;

[0133] S7022: When driven by the upper - layer (routing) protocol, the node needs to reserve a time slot (generally only needs to reserve one time slot resource according to the routing control message load), and this node is the source ID node;

[0134] S7023: The source ID node selects an idle time slot nearby (such as the information time slot Y in the figure) for competitive reservation. The information time slot Y is divided into W reservation cycles, and the node starts to attempt competition from the first reservation cycle;

[0135] S7024: The source ID node first sends a routing time slot request message. The time slot request message includes a routing time slot request identifier, the source ID, and a random idle time slot (randomly selected by the requesting node from its own list of idle time slots).

[0136] S7025: After receiving the message, if there is no collision and the idle time slot is available (i.e., the time slot is also idle for the one-hop node), the one-hop node of the source ID node does not make any response. If the source ID node does not receive any response during the reporting phase, it indicates that the time slot can be reserved, and then the source ID node makes a time slot reservation and sends a confirmation message during the confirmation phase. All one-hop nodes of the source ID node send response messages during the response phase. The response message includes a message identifier, the source ID, and the randomly selected idle time slot.

[0137] When a reservation cycle fails, it enters the subsequent reservation cycle for competition. If it is detected that another node has successfully reserved in a certain reservation cycle of this time slot, a new time slot is selected for reservation.

[0138] Optional solution: The requesting node does not specify a time slot, but only selects an idle time slot from the current list of idle time slots and competes for its reservation. The "request - report - confirmation - response" interaction process is also adopted. However, if the reservation is successful, the routing control message is sent in the same time slot of the next frame, that is, the default reservation is the current time slot of the next frame.

[0139] S7026: The source ID node, all its one-hop nodes, and the neighbor nodes of the one-hop nodes all learn that the reserved time slot is occupied and update their lists of idle time slots.

[0140] S7027: The source ID node sends a routing control message on the reserved time slot.

[0141] The present invention adopts distributed competitive reservation, reducing the conflict of shared channel usage and improving resource utilization.

[0142] III. Initial network access synchronization

[0143] The synchronization of the entire network is divided into initial network access synchronization during network construction and periodic synchronization during network operation. During the initial network access synchronization phase, more synchronization frames can be configured.

[0144] The main structure of the synchronization frame is as Figure 5 shown, including a scanning time slot, a master node synchronization time slot, and several groups of corresponding access time slots and synchronization time slots;

[0145] A scanning time slot is set at the beginning of the frame. All nodes do not send signals during this time slot. Each node can monitor the wide frequency spectrum working range during the scanning time slots of multiple synchronization frames. Among them, the master node can select an optimal frequency point according to the frequency scanning result.

[0146] The master node broadcasts its synchronization information in the master node synchronization time slot; the synchronization information includes synchronization code, frame number, time slot structure and frequency group, etc., where the time frame structure indicates the position of the current time slot, i.e., the #th frame and the #th time slot;

[0147] An access slot includes several access cycles.

[0148] Specifically, synchronization is performed through the following steps:

[0149] S301: After receiving the synchronization frame sent by its upper-level synchronization node, each node establishes one-way synchronization with its upper-level synchronization node, obtains the time frame structure and frequency group information, and multiple nodes compete for access in the access time slot to obtain the right to use the channel and forward the synchronization information. Among them, all nodes that establish one-way synchronization are source ID nodes, and the corresponding upper-level synchronization node is the target ID node;

[0150] S302: Each source ID node initiates an access request to the target ID node based on a certain probability, and competes for access in several access cycles of the corresponding access time slot; the access time slot is divided into multiple access cycles. When multiple nodes conflict in a certain access cycle, they enter the next cycle to compete again. If a node successfully competes for access in one of the cycles, the subsequent access cycle will not be used, and the subsequent synchronization time slot will be occupied by the node to forward the broadcast synchronization information.

[0151] When the source ID node successfully competes for access in a certain access period of the access time slot, the subsequent access period of the access time slot is no longer used, and the source ID node occupies the synchronization time slot immediately following the access time slot;

[0152] S303: After receiving the response message from the target ID node, the source ID node that successfully competes for access performs bidirectional synchronization with the target ID node.

[0153] S304: After the source ID node is successfully synchronized in both directions, the synchronization information is forwarded in the corresponding synchronization period, which is step S4.

[0154] The present invention uses the synchronization method to make the self-organizing network more suitable for multi-hop node synchronization and easier to expand.

[0155] Combination Figure 6 As shown, an access cycle includes three time segments: request, response and confirmation.

[0156] Specifically, the processing steps for contention access include:

[0157] S3021: In the request time segment of the current access cycle, the source ID node sends a forwarding synchronization request message to the target ID node; the forwarding synchronization request message includes a request identifier, a source ID (i.e., the ID of the source ID node), a destination ID (the ID of the target ID node. For example, for a one-hop node of the master node, its upper-level synchronization node is the master node), etc.;

[0158] S3022: After receiving the forwarding synchronization request message, the target ID node determines whether a collision is detected (i.e., whether multiple request messages are received in the current access cycle); if so, step S3023 is executed; otherwise, in the response time segment, a response message is sent to the source ID node, and S3024 is executed; the response message includes a response identifier, a time stamp, etc.;

[0159] S3023: The target ID node does not make any response in the response time segment. If the source ID node does not receive a response within the response time segment, it is considered that a collision has occurred with other source ID nodes, and then it waits for the competition in the subsequent access cycle;

[0160] The probability of collision between conflicting nodes can be reduced by sending probability and random integer cycle delay.

[0161] S3024: After receiving the response message, the source ID node confirms successful access to the competition and occupies the synchronization time slot immediately following this access time slot; at the same time, this response message will inform all other source ID nodes competing with the current source ID node that the corresponding synchronization time slot has been occupied;

[0162] S3025: The source ID node sends a forwarding synchronization confirmation message in the confirmation time segment, so that the one-hop node of this source ID node knows that the subsequent time slot has been occupied; the forwarding synchronization confirmation message includes a forwarding synchronization confirmation identifier.

[0163] In one access cycle, the request, response, and confirmation segments are all short message packets. In particular, the response and confirmation only have message identifiers. Therefore, more access cycles can be set in one access time slot, which can effectively improve the success rate of access time slot competition.

[0164] Based on unidirectional synchronization, the source ID node that has successfully completed the request access can estimate the propagation delay, so as to establish bidirectional synchronization with the master node or the upper-level synchronization node.

[0165] Through the above competition access method, the present invention enables the self-organizing network to have a high success rate and high efficiency in competition access, and supports distributed interaction.

[0166] Specifically, bidirectional synchronization is performed through the following steps:

[0167] S3031: Record the sending time of the source ID node's forwarding synchronization request message as T1;

[0168] S3032: Record the reception time of the source ID node's response message as T2;

[0169] S3033: Define that the message processing time of the source ID node during the request time segment and the response time segment in a successful contention access is T3;

[0170] S3034: Calculate the propagation delay ΔT through the following formula:

[0171]

[0172] S3035: The source ID node establishes two-way synchronization with the target ID node, i.e., the upper-level synchronization node, by adjusting the propagation delay ΔT.

[0173] The synchronization mechanism of the present invention can achieve two-way synchronization between multi-hop nodes during contention access, simplify protocol interaction, and improve self-synchronization accuracy.

[0174] The contention for each access time slot is a local event, supporting distributed interaction.

[0175] When the number of synchronization frames transmitted at frequency F1 is M, and the number of time slots in a synchronization frame is N (N is an even number, including a scanning time slot, a master node synchronization time slot, and several access time slot and synchronization time slot pairs). When a node receives synchronization information, it processes it according to the Figure 7 process shown.

[0176] Specifically, set the following broadcast or forwarding rules:

[0177] 1) To ensure that there is no conflict between two consecutive synchronization frames of the master node, the master node forwards the broadcast more than 3 hops in the previous synchronization frame before broadcasting the next synchronization frame, i.e., while reserving a certain margin, such as N = 12;

[0178] 2) When the previous synchronization frame is broadcast to the last time slot of this synchronization frame, the node that receives the synchronization frame can continue to perform contention access in the access time slot of the next synchronization frame;

[0179] 3) When a node needs to forward a synchronization frame, and the previous synchronization frame has not been successfully forwarded yet, and it receives the latest subsequent synchronization frame, it can only forward the latest received synchronization frame.

[0180] IV. Periodic Synchronization

[0181] To maintain synchronization during network operation, after initial network access synchronization, periodic synchronization also needs to be established. Its mechanism is the same as that of initial network access synchronization, except that fewer synchronization frames can be set for periodic synchronization, i.e., the configured M value is smaller than that of initial network access synchronization.

[0182] 5. Information Transmission

[0183] After synchronization between nodes, information is transmitted at the main frequency F1. A node needs to reserve a service time slot to support information transmission due to business drive. Distributed competitive reservation is adopted, and only the sending and receiving nodes compete for the service time slot locally.

[0184] like Figure 8 As shown, the processing steps of service time slot reservation include:

[0185] S601: Each node monitors one-hop information transmission and maintains an idle time slot list; the idle time slot list is a local time slot status information table;

[0186] S602: When a node is driven by upper-layer services and needs to reserve a service time slot to support information transmission, it is a source ID node; the source ID node selects a nearby idle time slot (such as information time slot X in the figure) to compete for reservation; information time slot X is subdivided into Q reservation cycles, and the node attempts to compete from the first reservation cycle;

[0187] S603: The source ID node learns the destination ID node to be sent according to the service driving information, and sends a time slot request message to the destination ID node; the time slot request message includes a time slot request identifier, a source ID (i.e., the ID of the current node), a destination ID, and information about the time slot to be applied for, wherein the information about the time slot to be applied for mainly includes two pieces of information: one is the number of time slots to be reserved; the other is the idle time slot vector (list) of the current node;

[0188] S604: The destination ID node receives the time slot request message and determines whether a collision occurs (i.e., whether multiple request messages are received in the reservation period): if a collision occurs, execute step S605; otherwise, execute step S606;

[0189] S605: The destination ID node does not reply to the task, and the source ID node makes another reservation in a subsequent reservation period; when the source ID node detects that another node has made a successful reservation in a reservation period of the current time slot, the time slot should be changed to make another reservation;

[0190] S606: The destination ID node replies with a time slot response message; the time slot response message includes a time slot response identifier, a source ID, a destination ID, and an available time slot, wherein the available time slot information is obtained by the destination ID node according to the received intended time slot information and by comparing the available time slot information table thereof;

[0191] S607: The source ID node receives the time slot response message replied by the destination ID node, completes the reservation of the corresponding time slot with the destination ID node, and sends a time slot confirmation message; the time slot confirmation message includes a time slot confirmation identifier, source ID, destination ID, and available time slots; through the time slot confirmation message (request-response-confirmation interaction process), nodes within one-hop range of both the source ID node and the destination ID node learn the message of the occupied reserved time slot, enabling these nodes to update the free time slot list they maintain;

[0192] S608: The source ID node transmits information on the main frequency based on the reserved time slot.

[0193] The present invention adopts distributed competitive reservation of information time slots, improving the utilization rate of shared channel resources.

[0194] In this embodiment, after the information transmission ends, the time slot resources can be announced for release, or the time slots can be released and reserved regularly, and local nodes should update the free time slot list in a timely manner.

[0195] Specifically, the generation of available time slots includes the following three cases:

[0196] 1) If the number of identical free time slots in the free time slot lists of both the source ID node and the destination ID node is greater than the number of time slots to be applied for, the destination ID node randomly selects time slots that meet the quantity requirements from them as available time slots;

[0197] 2) If the number of identical free time slots in the free time slot lists of both the source ID node and the destination ID node is equal to the number of time slots to be applied for, these free time slots are directly used as available time slots;

[0198] 3) If the number of identical free time slots in the free time slot lists of both the source ID node and the destination ID node is less than the number of time slots to be applied for, the destination ID node selects all the identical free time slots from them as available time slots, providing time slot resources for service (information transmission) degradation.

[0199] It should be noted that when the source ID node receives the time slot response message from the destination ID node, the number of identical free time slots cannot be 0, because at least the current information time slot X is free for both nodes.

[0200] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the technical solutions. Those of ordinary skill in the art should understand that any modifications or equivalent replacements made to the technical solutions of the present invention without departing from the purpose and scope of the present technical solution should be covered by the scope of the claims of the present invention.

Claims

1. A multi-frequency point synchronization control method for a self-organizing network, characterized in that, Including: S1: Configure a wide-spectrum operating frequency band for the ad hoc network, set N frequency points within the operating frequency band, and determine a primary frequency. S2: The master node broadcasts a synchronization frame containing synchronization information through N frequency points. S3: Each node receives the synchronization frame containing synchronization information sent by its upper-level synchronization node and performs synchronization; the upper-level synchronization node of the one-hop node of the master node is the master node. S4: After the nodes complete synchronization, forward the synchronization frame containing synchronization information with a certain probability and return to step S3. S5: Periodically repeat steps S2 to S4 to complete the periodic synchronization of all nodes in the ad hoc network. S6: Each node makes a reservation for the service time slot with the target node according to the service-driven information and transmits information based on the reserved time slot on the primary frequency. S7: Update the frequency points and primary frequency of the operating frequency band according to the scenario change and electromagnetic environment.

2. The self-organizing network multi-frequency point synchronization control method according to claim 1, characterized in that: In step S2, the synchronization frame sent by the master node includes a scanning time slot, a master node synchronization time slot, and several groups of corresponding access time slots and synchronization time slots. The master node broadcasts its synchronization information in the master node synchronization time slot. One access time slot includes several access cycles. One access cycle includes three time segments: request, response, and confirmation.

3. The multi-frequency point synchronization control method for a self-organizing network according to claim 2, characterized in that: In step S3, synchronization is performed through the following steps: S301: After each node receives the synchronization frame sent by its upper-level synchronization node, establish one-way synchronization with its upper-level synchronization node; among them, all nodes that establish one-way synchronization are source ID nodes, and the corresponding upper-level synchronization nodes are target ID nodes. S302: Each source ID node initiates an access request to the target ID node based on a certain probability and competes for access in several access cycles of the corresponding access time slot. When the source ID node successfully competes for access in a certain access cycle of the access time slot, the subsequent access cycles of this access time slot are no longer used, and this source ID node occupies the synchronization time slot immediately following this access time slot. S303: After the source ID node that has successfully competed for access receives the response message from the target ID node, perform two-way synchronization with it.

4. The self-organizing network multi-frequency point synchronization control method according to claim 3, characterized in that: In step S302, the processing steps for competing for access include: S3021: In the request time segment of the current access cycle, the source ID node initiates a forwarded synchronization request message to the target ID node. S3022: After the target ID node receives the forwarded synchronization request message, determine whether a collision is detected; if so, execute step S3023; otherwise, reply with a response message to the source ID node in the response time segment and execute S3024. S3023: The target ID node does not make any response in the response time segment, and the source ID node does not receive a response within the response time segment, that is, it is considered that a collision has occurred with other source ID nodes, and then wait for the competition in the subsequent access cycle. S3024: After the source ID node receives the response message, confirm that the competition for access is successful and occupy the synchronization time slot immediately following this access time slot; at the same time, this response message will inform all other source ID nodes that compete with the current source ID node that the corresponding synchronization time slot has been occupied. S3025: The source ID node sends a forwarded synchronization confirmation message in the confirmation time segment to enable the one-hop node of this source ID node to know that the subsequent time slot has been occupied.

5. The multi-frequency point synchronization control method for a self-organizing network according to claim 3, characterized in that: In step S303, two-way synchronization is performed through the following steps: S3031: record the sending time of the source ID node forwarding the synchronization request message as T1; S3032: record the receiving time of the source ID node response message as T2; S3033: define the message processing time of the source ID node in a successful contention access in the request time segment and the response time segment as T3; S3034: Calculate the propagation delay ΔT using the following formula: S3035: The source ID node establishes bidirectional synchronization with the target ID node, i.e., the previous-level synchronization node, by adjusting the propagation delay ΔT.

6. The self-organizing network multi-frequency point synchronization control method according to claim 1, characterized in that: In step S3, the following broadcast or forwarding rules are set: 1) The master node forwards the previous synchronization frame for more than 3 hops before broadcasting the next synchronization frame; 2) When the previous synchronization frame is broadcast to the last time slot of the current synchronization frame, the node receiving the synchronization frame continues to compete for access in the access time slot of the next synchronization frame; 3) When a node needs to forward a synchronization frame, and the previous synchronization frame has not been successfully forwarded, and the next latest synchronization frame is received, only the latest received synchronization frame is forwarded.

7. The multi-frequency point synchronization control method for the self-organizing network according to claim 1, characterized in that: In step S6, the processing steps of service time slot reservation include: S601: Each node monitors one-hop information transmission and maintains a list of idle time slots; S602: When a node is driven by upper-layer services and needs to reserve a service time slot to support information transmission, it is a source ID node; the source ID node selects a nearby idle time slot for competition reservation; the time slot is divided into several reservation cycles, and the source ID node tries to compete from the first reservation cycle; S603: The source ID node learns the destination ID node to be sent according to the service driving information, and sends a time slot request message to the destination ID node; S604: The destination ID node receives the time slot request message and determines whether a collision occurs: if a collision occurs, execute step S605; otherwise, execute step S606; S605: The destination ID node does not reply to the task, and the source ID node makes another reservation in a subsequent reservation period; when the source ID node detects that another node has made a successful reservation in a reservation period of the current time slot, the time slot should be changed to make another reservation; S606: The destination ID node replies with a time slot response message; the time slot response message includes available time slots, wherein the available time slot information is obtained by the destination ID node according to the received intended time slot information and by comparing the available time slot information table thereof; S607: The source ID node receives the time slot response message replied by the destination ID node, completes the reservation of the corresponding time slot with the destination ID node, and sends a time slot confirmation message; through the time slot confirmation message, the nodes within one hop range of the source ID node and the destination ID node are informed of the message of the reserved time slot occupancy, so that these nodes can update the idle time slot list they maintain; S608: The source ID node transmits information on the main frequency based on the reserved time slot.

8. The multi-frequency point synchronization control method for an ad hoc network according to claim 7, wherein: In step S606, the generation of available time slots includes the following three situations: 1) If the number of the same idle time slots in the idle time slot lists of the source ID node and the destination ID node is greater than the number of time slots to be applied for, the destination ID node randomly selects a time slot that meets the quantity requirement as an available time slot; 2) If the number of identical idle time slots in the idle time slot lists of both the source ID node and the destination ID node is equal to the number of time slots to be applied for, these idle time slots are directly used as available time slots; 3) If the number of identical idle time slots in the idle time slot lists of both the source ID node and the destination ID node is less than the number of time slots to be applied for, the destination ID node selects all the identical idle time slots as available time slots from them, providing time slot resources for service (information transmission) degradation.

9. The self-organizing network multi-frequency point synchronization control method according to claim 1, characterized in that: In step S7, the frequency point adjustment is performed through the following steps: S701: The master node scans and senses the spectrum in the scanning time slot. According to the section division, it selects the frequency points with the best quality in the frequency section to form a frequency group, and broadcasts a synchronization announcement message including the frequency group information synchronously on multiple frequency points; S702: While receiving the synchronization announcement message, each node monitors the quality of each frequency point in the frequency group, divides the frequency point quality into multiple quality levels, and attaches the frequency group quality level information to the routing control message, which is periodically aggregated to the master node; S703: The master node makes a decision on the frequency point adjustment plan according to the frequency group quality level information monitored by each node: In the frequency group, when a certain frequency point is available and the number of nodes detecting the availability of this frequency point is the largest, this frequency point is configured as the main frequency; when there are two or more frequency points with the same and largest number of available nodes, the one with a higher average quality level after being detected by all nodes is selected as the main frequency; When one of the following two situations occurs, the master node needs to rescan the frequency points to update the frequency group: 1) The number of nodes detecting the availability of the main frequency is lower than the preset threshold; 2) The number of nodes detecting the availability of more than half of the frequency points in the frequency group is lower than the preset threshold; S704: The master node synchronizes and announces the adjustment information in the new frequency group.

10. The multi-frequency point synchronization control method for a self-organizing network according to claim 9, wherein: In step S702, it specifically includes the following steps: S7021: Each node monitors the one-hop information transmission and maintains an idle time slot list; S7022: When driven by the upper-layer protocol, the node needs to reserve a time slot, and this node is the source ID node; S7023: The source ID node selects an idle time slot nearby for competitive reservation; the time slot is divided into several reservation cycles, and the node starts to try to compete from the first reservation cycle; S7024: The source ID node first sends a routing time slot request message; After the one-hop node of the source ID node receives it, if there is no collision conflict and this idle time slot is available, it does not make any response; if the source ID node does not receive any response during the reporting stage, it indicates that this time slot can be reserved, and then it makes a time slot reservation and sends a confirmation message during the confirmation stage. The one-hop nodes of the source ID node all send response messages during the response stage; When a reservation cycle fails to make a reservation, it transfers to the subsequent reservation cycle for competition; if it is detected that another node makes a reservation successfully in a certain reservation cycle of this time slot, it selects a new time slot to make a reservation again. S7026: The source ID node and all its one-hop nodes, as well as the neighbor nodes of the one-hop nodes, all learn that the reserved time slot is occupied and update their idle time slot lists; S7027: The source ID node sends a routing control message on the reserved time slot.

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