CN110248320B - Wireless self-organizing network management method based on time synchronization and frequency synchronization - Google Patents
Wireless self-organizing network management method based on time synchronization and frequency synchronization Download PDFInfo
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Abstract
The invention relates to the technical field of wireless self-organizing networks, in particular to a wireless self-organizing network management method based on time synchronization and frequency synchronization. A node directly associated to the root node enters a multicast reception slot at a frequency F1 to receive the root node information at the same time; and after the multicast time slot is finished, the root node enters a unicast time slot. And if the node is the terminal node, entering a unicast time slot. If the node is a father node, namely a routing node, the frequency is switched to F2 to enter a multicast sending time slot, and multicast information is sent. And finally, each layer of nodes in the tree topology structure executes a synchronization process until the node farthest from the root node completes the unicast time slot, and one cycle is finished. The invention avoids the conflict with the nearby nodes in a frequency hopping communication mode in three time slots, and improves the success rate of communication.
Description
Technical Field
The invention relates to the technical field of wireless self-organizing networks, in particular to a wireless self-organizing network management method based on time synchronization and frequency synchronization, which can control and manage the communication process between nodes.
Background
The application based on the wireless self-organizing network is more and more extensive, for example, the application of intelligent home, intelligent agriculture, environment monitoring, intelligent light control and the like, and it is one of the important purposes of using the wireless self-organizing network that each terminal device can be in a monitoring and controllable state. Taking smart homes as an example, a home may have tens or more devices to be controlled, such as a refrigerator, a washing machine, a heating valve, a desk lamp, a curtain, a water heater, etc. In order to enable a set of algorithms or strategies suitable for smart home to automatically complete various adjustment tasks, an interface based on physical connection must be provided between the algorithms and the devices. When the indoor temperature is too high, the algorithm needs to turn on the ventilation device to dissipate heat, when the indoor is too dry, the algorithm needs to turn on the humidification device to adjust the air humidity, and the like. The simplest way to achieve control is to establish a wired connection from the terminal device to the server. The algorithm may be run on a server and control signals sent over a wired connection when it is desired to operate the device. However, when more and more devices are connected to the smart home environment, two problems need to be considered, namely, the more the devices, the more the cable connection is complicated. Secondly, the equipment may be in any position, and the overlong cable may cause the signal to be attenuated below the effective range, or sometimes cannot be laid due to the problem of the building structure. Both of these situations are encountered in many situations. Therefore, it is a suitable solution to solve the problem using a wireless ad hoc network.
Fig. 11 schematically shows the basic structure of a wireless ad hoc network, wherein routing nodes serve as the backbone of the network and communicate with network devices distributed at different locations. The routing node can be fixedly installed or generated by network protocol calculation selection. If the network rarely changes the position of the equipment after installation, the routing node can be connected with the main power supply, and a sleep mode is not adopted in the working process, so that data can be received and a forwarding task can be executed at any time. Terminal device generally refers to a device that needs to be monitored or controlled, such as a desk lamp in an intelligent home, or a temperature sensor. The end devices do not directly participate in the routing process because in many cases the radio transceivers of the end devices are battery powered, so the devices are in a dormant state most of the time to save power. When an application needs, the device is awakened to complete a predetermined task, and then the task result is handed to the routing device to be transmitted to the destination. The gateway device is also typically a routing device and has the capability of forwarding data within the ad hoc network and communicating between the ad hoc network and an external network. By using a wireless ad hoc network, the system allows devices distributed at different locations to connect to the network. When the physical distance between the devices exceeds the point-to-point communication distance of the wireless transceiver, the routing node is added, so that the rapid expansion can be realized at low cost. Due to the use of wireless communication, the number of the connected devices can be increased or decreased freely without being limited by the number of the physical interfaces of the devices per se and without exceeding the processing capacity of the wireless communication.
While wireless communication has clear advantages in use, there are still many problems. Because cable connection is not used, communication between nodes can be realized only in a wireless mode, and the anti-interference capability of the system is inferior to that of a wired system. Due to the distributed structure of the wireless self-organizing network, no node in the network can be used as a central controller to arrange the communication sequence of all other nodes, and the global flow control is difficult to realize. The problems encountered by wireless ad hoc networks in applications can be summarized as follows:
1. since the process of wireless communication takes place in the air and there is no way to protect the physical signals, interference and collision between signals can easily occur.
2. Each node only communicates with its own neighbor node, and when the distance between nodes exceeds the direct communication distance of the wireless transceiver, the intermediate node must be relied upon for forwarding. This approach, while extending network coverage, does not allow a central control point in the network to directly contact all other nodes. Therefore, the various communications occurring in the network are in a random state as a whole, further increasing the probability of interference/collision, resulting in communication failure.
3. Reliable broadcast/multicast communication. This problem is relatively simple in a wired network because devices are connected to each other via a cable, and a device transmitting data on a port must be received by a device connected to the other end of the port. In a wireless network, it is difficult for a node sending a broadcast to fully know the information of all neighbors in the vicinity, and because broadcast/multicast communication does not usually require a receiver to send a receipt to confirm receipt, the sender cannot confirm whether the message was successfully sent.
4. There is also a problem with the use of broadcast/multicast in wireless ad hoc networks, namely the determination of forwarding nodes. If each node participates in the forwarding process, a network storm can form. But if the coverage of the nodes participating in the forwarding is not sufficient to reach the entire network, the forwarding becomes invalid or partially invalid.
Disclosure of Invention
The invention provides a wireless self-organizing network management method based on time synchronization and frequency synchronization aiming at the problem of the wireless self-organizing network in use, which avoids the interference between signals and improves the reliability of communication.
In order to realize the purpose of the invention, the adopted technical scheme is as follows: a wireless self-organizing network management method based on time synchronization and frequency synchronization comprises a full-network multicast process started by a root node and a full-network multicast process started by a non-root node,
the root node, the terminal node and the routing node form a tree topology structure, the upper layer associated node is called a father node, and the lower layer associated node is called a child node;
the whole network multicast process starting from the root node comprises the following steps:
1) the root node enters a multicast sending time slot on the frequency F1, and the child nodes directly related to the root node synchronously enter a multicast receiving time slot on the frequency F1 to receive the information sent by the root node;
2) the method comprises the steps that a root node finishes a multicast sending time slot, enters a unicast time slot, enters a child node directly related to the root node if the root node is a terminal node, enters a unicast time slot if the root node is a routing node, enters a multicast sending time slot at a frequency F2 after the multicast receiving time slot at a frequency F1 is finished, and sends multicast messages, synchronously rotates the child node related to the routing node to a frequency F2 to enter a multicast receiving time slot to receive multicast messages, enters the unicast time slot after the routing node finishes the multicast sending time slot, and if a plurality of routing nodes on the same layer as the routing node are arranged on a topological structure, the frequency F2 of multicast sending of each routing node is different;
3) each layer of nodes in the tree topology structure executes the synchronization process in the step 2) until the node farthest from the root node completes the unicast time slot, and one cycle is finished;
the whole network multicast process started by a non-root node comprises the following steps:
A. when the non-root node is a terminal node, the terminal node sends the multicast message to the associated routing node in a unicast time slot, namely a father node of the terminal node, the routing node multicasts the multicast message in a downlink direction in the multicast sending time slot, if the routing node has the father node, the routing node sends the multicast message to the father node in the unicast time slot, the father node continues multicasting in the downlink direction in the multicast sending time slot and sends the multicast message to the superior father node in the unicast time slot, the process continues until the superior father node, namely the root node receives the message and finishes the process of sending the multicast message to other routing nodes and terminal nodes associated with the root node;
B. when the non-root node is a routing node, the routing node needs to send multicast messages to the father routing node in the unicast time slot and starts downlink multicast in the multicast sending time slot, the father node which receives the multicast messages in the unicast time slot needs to discover the multicast in the downlink and also sends the multicast messages to the father node of the routing node in the unicast time slot until the root node is reached, and the root node completes the process of sending the multicast messages by other routing nodes and terminal nodes which are related to the root node.
As an optimization scheme of the present invention, the value of the frequency F2 is determined by the address of the node or the level of the topology where the node is located.
As an optimization scheme of the invention, the wireless self-organizing network management method based on time synchronization and frequency synchronization also comprises a communication method in a unicast time slot, and comprises the following steps:
a. all nodes listen in unicast time slots on a frequency F3, a communication initiator transmits a data request containing a communication destination node address and a communication frequency F4 on a frequency F3, then the communication initiator jumps to a communication frequency F4 to keep a receiving state, the communication frequency F4 is generated by the communication initiator in a random or designated manner before transmitting the data request, namely F4 is distinguished each time the data request is generated;
b. if the communication destination node successfully receives the data request and judges that the communication can be completed in the remaining time of the unicast time slot, jumping to a communication frequency F4, and then sending a prompt for the communication initiator to send data, wherein the communication initiator starts to send data after receiving the prompt;
c. after the communication initiator finishes sending data, if the communication initiator does not require confirmation, the communication is finished, and the communication initiator returns to the frequency F3; if the communication initiator requires to receive an acknowledgement, waiting for a period of time, acknowledging receipt, the communication being successful, if no acknowledgement is received, the communication failing, whether successful or not, the communication initiator returning to frequency F3; after that, if the communication fails, the communication initiator retries transmission at the next appropriate time on the frequency F3;
d. after waiting for a period of time at the communication frequency F4, if a prompt for the communication initiator to send data is not received from the communication destination node, the communication fails, and the communication initiator returns to the frequency F3 to wait for the next attempt;
e. the destination node goes to the communication frequency F4, waits for a period of time after sending a prompt for the originator to send data, and if no data is received, the destination node goes back to the frequency F3.
As an optimization scheme of the invention, the root node is a gateway node.
As an optimization scheme of the invention, the multicast receiving time slot of the child node is a time slot synchronous with the multicast sending time slot of the parent node associated with the child node.
As an optimization scheme of the invention, the unicast time slot length of the father node is equal to the unicast time slot length of the father node minus one multicast transmission time slot of the father node.
The invention has the positive effects that: 1) in order to improve the success rate of communication, the communication avoids the conflict with nearby nodes in a frequency hopping mode in three time slots;
2) the multicast sending time slot and the multicast receiving time slot of the invention work on the appointed frequency, but the unicast time slot starts on the frequency unified by the whole network. The purpose of setting is to enable the nodes, especially the nodes which are newly added into the network and have not completed synchronization, to be in contact with the existing network nodes in the fastest way, and the networking speed in the whole process is high;
3) the invention adopts a communication mode combining unicast and multicast, and ensures reliable broadcast/multicast communication.
Drawings
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
FIG. 1 is a schematic diagram of an ad-hoc network forming a tree topology;
FIG. 2 is a schematic diagram of a slot distribution;
FIG. 3 is a schematic diagram of the communication of a unicast slot end node and a routing node;
FIG. 4 is a workflow diagram of a root node;
FIG. 5 is a flowchart of the operation of the end node;
FIG. 6 is a workflow diagram of a parent node;
FIG. 7 is a flow chart of the operation of a communication initiator in a unicast slot;
FIG. 8 is a flow chart of the operation of a communication recipient in a unicast slot;
FIG. 9 is a flow diagram of a network-wide multicast process from a root node;
FIG. 10 is a flow diagram of a network-wide multicast process starting from a non-root node;
fig. 11 is a schematic diagram of a conventional wireless ad hoc network.
Detailed Description
The invention discloses a wireless self-organizing network management method based on time synchronization and frequency synchronization, which comprises a whole network multicast process started by a root node and a whole network multicast process started by a non-root node,
as shown in fig. 1, the root node, the terminal node and the routing node form a tree topology structure, the associated nodes at the upper layer are called parent nodes, and the associated nodes at the lower layer are called child nodes; after the tree topology structure is formed, time synchronization is carried out on a father node and a child node, the purpose of synchronization is to divide time into fixed time slots, in the topology structure, the father node is closer to a root node than the child node, and the synchronization is divided into 3 time slots, multicast receiving time slots, multicast sending time slots and unicast time slots.
The whole network multicast process starting from the root node comprises the following steps:
1) the root node enters a multicast sending time slot on the frequency F1, and the child nodes directly related to the root node synchronously enter a multicast receiving time slot on the frequency F1 to receive the information sent by the root node;
2) the method comprises the steps that a root node finishes a multicast sending time slot, enters a unicast time slot, enters a child node directly related to the root node if the root node is a terminal node, enters the unicast time slot if the root node is a routing node, enters a multicast sending time slot at a frequency F2 for sending a multicast message after the routing node finishes a multicast receiving time slot at a frequency F1, synchronously turns to a frequency F2 with the child node related to the routing node to enter the multicast receiving time slot for receiving the multicast message, and enters the unicast time slot after the routing node finishes the multicast sending time slot. If there are a plurality of routing nodes topologically on the same layer as the routing node, each routing node performs multicast transmission using a different frequency F2. The specific determination of the frequency F2 may be generated by specific conditions such as the address of the node or the hierarchy of the topology where the node is located; in the multicast sending time slot, a father node sends the multicast message to the child nodes related to the father node, and the child nodes can only receive in the time slot and can not send, so as to avoid interfering the sending of the multicast message to the father node. A multicast receive slot is a slot in which each node synchronizes with the multicast transmit slot of its associated parent node. Each node in the multicast receive slot can only listen on the radio frequency and cannot transmit. Unicast slots are used for point-to-point unicast communications. Unicast may be from a parent node to a child node or from a child node to a parent node. Unlike multicast, unicast communication procedures allow for the existence of contention, while also allowing for acknowledgement mechanisms to ensure reliable communication.
3) Each layer of nodes in the tree topology structure executes the synchronization process in the step 2) until the node farthest from the root node completes the unicast time slot, and one cycle is finished;
the whole network multicast process started by a non-root node comprises the following steps:
A. when the non-root node is a terminal node, the terminal node sends the multicast message to the associated routing node in a unicast time slot, the routing node multicasts the multicast message to the downlink direction in the multicast sending time slot, if the routing node has a father node, the routing node sends the multicast message to the father node in the unicast time slot, the father node continues to multicast to the downlink direction in the multicast sending time slot, the process of sending the multicast message to the superior father node is continuously carried out until the superior father node, namely the root node receives the message, and the process of sending the multicast message to other routing nodes and the terminal node associated with the root node is completed;
B. when the non-root node is a routing node, the routing node needs to send multicast messages to a father routing node in a unicast time slot and starts downlink multicast in a multicast sending time slot, the father node which receives the multicast messages in the unicast time slot needs to find the multicast in the downlink and sends the multicast messages to the father node of the routing node in the unicast time slot until the root node is reached, and the root node completes the process of sending the multicast messages by other associated routing nodes and terminal nodes.
The wireless self-organizing network management method based on time synchronization and frequency synchronization also comprises a communication method in a unicast time slot, and comprises the following steps:
a. all nodes listen on frequency F3 during the unicast slots. The communication originator transmits a data request containing the communication destination node address and the communication frequency F4 on the designated frequency F3, and then the communication originator jumps to the communication frequency F4 to maintain the receiving state. The communication frequency F4 is generated by the communication initiator in a random or designated manner before sending the data request, i.e., each time the data request is generated, F4 is different;
b. if the communication destination node successfully receives the data request and judges that the communication can be completed in the remaining time of the unicast time slot, jumping to a communication frequency F4, and then sending a prompt for the communication initiator to send data, wherein the communication initiator starts to send data after receiving the prompt;
c. after the communication initiator finishes sending data, if the communication initiator does not require confirmation, the communication is finished, and the communication initiator returns to the frequency F3; if the communication initiator requires to receive an acknowledgement, waiting for a period of time, acknowledging receipt, the communication being successful, if no acknowledgement is received, the communication failing, whether successful or not, the communication initiator returning to frequency F3; after that, if the communication fails, the communication initiator retries transmission at the next appropriate time on the frequency F3;
d. after waiting for a period of time at the communication frequency F4, if a prompt for the communication initiator to send data is not received from the communication destination node, the communication fails, and the communication initiator returns to the frequency F3 to wait for the next attempt;
e. the destination node goes to the communication frequency F4, waits for a period of time after sending a prompt for the originator to send data, and if no data is received, the destination node goes back to the frequency F3.
As shown in fig. 2, fig. 2 is a schematic diagram of time slot distribution, starting with cycle 1, and in the initial stage of cycle 1, the root node enters a multicast transmission time slot on frequency 1(f 1). In this time slot, if the root node has a message to be multicast-sent, it can perform multicast communication. For other nodes having the root node as a parent node, it is necessary to start entering the multicast reception slot on frequency 1 in synchronization with the multicast transmission slot of the root node. Here, the end node 2 and the routing node 2 in fig. 1 are taken as examples. In the multicast reception time slot, the routing node 2 and the terminating node 2 are not allowed to transmit any data, and can listen only on frequency 1. This ensures that multicast messages sent from the root node can be reliably delivered to the child nodes. When the multicast send slot of the root node ends (and the multicast receive slots of both the routing node 2 and the terminating node 2 end), it enters a unicast slot. For end node 2, it does not need to send multicast messages to the lower layers because there is no child node and its association. Both end node 2 and the root node enter unicast slots. In the unicast slot, the terminal node 2 and the root node 2 can communicate with each other. The routing node 2 is associated with the routing node 3 and serves as a parent node thereof, so that the routing node 2 needs to reserve the opportunity of sending the multicast message to the routing node 3, and the routing node 2 enters the multicast sending time slot on the frequency 2 immediately after the multicast receiving time slot on the frequency 1 is finished. While routing node 3 enters the multicast receive slot on frequency 2 and remains synchronized with routing node 2. After completing the multicast transmission time slot on the frequency 2, the routing node 2 enters the unicast time slot. Because the routing node 5 is associated with the routing node 3 and has it as a parent node, the routing node 3 enters the frequency 3 to perform a multicast transmission slot after completing the multicast reception slot on the frequency 2. Accordingly the routing node 5 also synchronises into the multicast reception slot on frequency 3. When the routing node 5 completes the multicast receive slot on frequency 3, the routing node 5 enters the multicast transmit slot on frequency 4 because there are more end nodes 4 associated with it. When the routing node 5 completes the multicast transmission time slot on the frequency 4, it enters the unicast time slot. The terminal node 4 enters a unicast slot because it has no child node. When all nodes on the tree topology structure finish a multicast sending time slot, a multicast receiving time slot and a unicast time slot, one cycle is finished, and a second cycle is started from the root node.
When the tree topology is formed, each network node which becomes a father node needs to communicate with the father node of the network node to complete the distribution of the multicast sending time slot frequency. Nodes associated with the same parent node need to use different multicast transmission frequencies to avoid interference with each other. In fig. 2, f1, f2, f3, and the like are shown differently.
Again, the slot length is allocated. The multicast transmission time slot and the multicast reception time slot length are defined according to the adopted physical layer standard of the wireless communication technology, i.e. the time consumed for transmitting a data packet with a certain length. The complete data packet transmission usually includes preamble, header, packet payload, packet trailer, and other contents, and may additionally require radio frequency transceiving conversion, radio frequency settling time, and synchronization calibration. Each node needs to perform at least a multicast receive slot and a unicast slot in one cycle, and also needs to perform a multicast transmit slot if its network role is a parent node. Therefore, in principle, if a node is an end node, its unicast slot length coincides with the unicast slot length of its parent node, such as T2 of end node 2 and T1 of the root node in fig. 2. If a node is a parent, its unicast slot length is equal to the unicast slot length of its parent minus a multicast transmission slot length, such as T3 of routing node 2 in FIG. 2 is equal to T1 of the root node minus a multicast transmission slot.
As shown in fig. 3, fig. 3 shows a unicast slot communication scheme between the end node 5 and the routing node 5, where both the multicast transmission slot and the multicast reception slot operate on a designated frequency, but the unicast slot needs to start on a frequency uniform throughout the network. The purpose of this is to enable the nodes, especially those that have not yet completed synchronization with the newly added network, to contact the existing network nodes in the fastest way. The working mode of the unicast time slot is divided into two parts, namely, monitoring on the same frequency of the designated whole network, and completing data receiving and transmitting work on the designated frequency. In the unicast slots, the end node 5 has data to send to the routing node 5. Each node listens on the uniform frequency X during unicast slots, so that the end node first sends a data request on frequency X, including the destination address of the communication (routing node 5) and the frequency Y at which data transmission will subsequently take place. If the routing node successfully receives the request of the terminal node 5 and determines that the communication can be completed within the remaining time of the unicast slot, the routing node 5 jumps to the frequency Y. After sending the data request, the end node 5 also jumps to frequency Y and keeps listening. When the routing node 5 reaches frequency Y, a transmission instruction allows the end node 5 to transmit data. The end node 5 will only start sending data if it successfully receives this indication. If the data is successfully received by the routing node 5 and an acknowledgement is required to be sent as an option, an acknowledgement of receipt is sent. Then both the end node 5 and the routing node 5 return to the uniform frequency X and the communication is completed. In the whole communication process, if any interaction does not receive a corresponding answer, the communication fails, and the nodes all return the uniform frequency X. Such as: if the routing node does not receive the data transmission request of the terminal node 5 on the frequency X, the terminal node 5 returns the frequency X when the terminal node 5 finds that the transmission instruction is not received after waiting for a fixed time after jumping to the frequency Y. If the routing node 5 jumps to the frequency Y and issues a transmission instruction, but the data transmission of the terminal node 5 is not received after a fixed time, the routing node 5 returns the frequency X. If the terminal node does not receive a reception acknowledgement after sending the data, it also returns to frequency X to prepare for the second attempt, or waits for the next available unicast slot if the remaining unicast slot is not long enough to complete the communication.
The types of data communication are divided into multicast communication and unicast communication, wherein the multicast communication is divided into top-to-bottom and bottom-to-top.
Multicast communication from top to bottom: assuming that the originator of the multicast communication is the root node of the network, the communication is intended to distribute the message to all nodes in the network. The root node may send out the message in a multicast send slot. Its child node will receive the message in the multicast receive slot. If the current node is the terminal node, the multicast is finished. If the current node is a parent node, the message is forwarded to its child nodes in the next multicast transmission slot. The forwarding process continues until all nodes in the network receive the message.
Multicast communication from bottom to top: assuming that a node other than the root node is to perform multicast, if the node is a parent node, the message is sent out in the multicast transmission time slot of the node, and all the child nodes associated with the parent node and the child nodes of the child nodes are multicast by using a top-down multicast communication mode. The multicast message is reliably transmitted to the parent node of the node in the unicast time slot of the node, and the parent node broadcasts the message to other child nodes and the parent node of the parent node in the multicast transmission time slot and the unicast time slot of the parent node respectively. This process is repeated until all nodes in the network receive the multicast message.
If the current node is a terminal node, there are no child nodes. In the unicast time slot of the node, the node reliably sends the message to the parent node of the node. The father node forwards the message to the father node of the upper layer in the unicast time slot of the father node, and simultaneously sends the message to the downlink in the multicast sending time slot of the father node, and the multicast process is carried out from top to bottom. The parent node of the upper level repeats the same process until all nodes in the network receive the multicast message, wherein unicast communication from the parent node to the parent node of the upper level stops at the root node.
As shown in fig. 4-6, the steps of slot synchronization are:
(1) firstly, a tree-shaped topological structure is formed, and the time in the network is synchronized by a specified time slot from a root node;
(2) the root node sends out the first time slot, the multicast send time slot, at frequency F1. A node directly associated to the root node enters a multicast reception slot at a frequency F1 to receive the root node information at the same time;
(3) the root node finishes the multicast sending time slot and enters the unicast time slot. And if the node is the terminal node, entering a unicast time slot. If the node is a father node, namely a routing node, the frequency is switched to F2 to enter a multicast sending time slot, and multicast information is sent. The child node associated with the parent node synchronously switches to frequency F2 to enter a multicast receiving time slot to receive multicast information. And when the father node finishes the multicast sending time slot, entering the unicast time slot. If there are multiple routing nodes in the child nodes associated with the root node, the frequency F2 of the multicast transmission time slot of each routing node should be different from each other;
(4) and (3) each layer of nodes in the tree topology structure executes the synchronization process in the step (3) until the node farthest from the root node completes the unicast time slot, and one cycle is finished. The root node resumes slot synchronization.
As shown in fig. 7-8, the communication steps of the unicast slot are:
1) a communication initiator sends a data sending request on a specified uniform frequency, wherein the request comprises a communication destination node address and a communication frequency, the communication frequency is usually different from the uniform frequency, and after the request is sent out, the communication initiator jumps to the communication frequency specified in the data sending request and keeps a receiving state;
2) and if the communication destination node successfully receives the data transmission request, analyzing the request. If the current conditions can continue to communicate, such as the time remaining in the current unicast slot can complete the communication, then a jump is made to the communication frequency contained in the data transmission request. If the communication destination node does not receive the data sending request or the current condition is judged to be insufficient for communication, no action is taken;
3) and after the communication destination node jumps to the data communication frequency, sending a data sending prompt. The prompt indicates which node is allowed to send data. And when receiving the prompt, the communication initiating node starts to send data. After the data transmission is finished, if the communication initiating node does not require confirmation, the communication is finished, and the initiating node returns to the specified uniform frequency. If the communication initiating node requires to receive the confirmation, waiting for a period of time, confirming the receipt, and the communication is successful, if the confirmation is not received, the communication is failed, and the initiating node returns the uniform frequency no matter whether the communication is successful or not. After returning, if the communication fails, the initiating node retries to send at the next appropriate time;
4) after the communication initiating node waits for a period of time on the communication frequency, if the data transmission prompt of the communication destination node is not received, the communication fails, and the initiating node returns to the uniform frequency to wait for the next attempt.
5) And the communication destination node transfers to the communication frequency, waits for a period of time after sending the data sending prompt, and transfers to the uniform frequency if the data is not received.
As shown in fig. 9, the whole network multicast process from the root node:
1) the root node transmits multicast information in a multicast transmission time slot on the frequency F1;
2) the child node associated with the root node starts a multicast reception slot in synchronization with the multicast transmission slot of the root node at frequency F1;
3) if the child node associated with the root node is also a parent node and there are other child nodes associated with it, the parent node enters the frequency F2 to start the multicast transmission time slot after the multicast reception time slot on the frequency F1 is finished. The node transmits a multicast message within a transmission time slot. Different routing nodes connected to the same parent node should multicast the transmission time slot on different frequencies F2;
4) if the multicast has not reached the maximum depth of the network, executing step 3), otherwise ending.
As shown in fig. 10, the whole network multicast process starting from the non-root node:
(1) if the node is an end node, the message is sent to the associated parent node in a unicast slot. And multicasting by the parent node in the downlink direction in the multicast sending time slot. If the father node is associated with a higher-level father node, the message is sent to the higher-level father node in the unicast time slot of the father node, and the higher-level father node continues to perform multicast sending time slot in the downlink direction. The process of sending the multicast message to the superior parent node in the multicast time slot continues until the root node is reached. Each father node receiving the message executes the multicast in the downlink direction;
(2) if the node is a routing node, namely a father node, the node needs to send a multicast message to an upper father node in a unicast time slot and starts a downlink multicast process in the multicast sending time slot. The superior father node receiving the message in the unicast time slot repeats the multicast sending process in the downlink direction, and also sends the message to the superior father node in the unicast time slot until reaching the root node.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. The wireless self-organizing network management method based on time synchronization and frequency synchronization is characterized in that: including a full network multicast process starting with a root node and a full network multicast process starting with a non-root node,
the root node, the terminal node and the routing node form a tree topology structure, the upper layer associated node is called a father node, and the lower layer associated node is called a child node;
the whole network multicast process starting from the root node comprises the following steps:
1) the root node enters a multicast sending time slot on the frequency F1, and the child nodes directly related to the root node synchronously enter a multicast receiving time slot on the frequency F1 to receive the information sent by the root node;
2) the method comprises the steps that a root node finishes a multicast sending time slot, enters a unicast time slot, enters a child node directly related to the root node if the root node is a terminal node, enters a unicast time slot if the root node is a routing node, enters a multicast sending time slot at a frequency F2 after the multicast receiving time slot at a frequency F1 is finished, and sends multicast messages, synchronously rotates the child node related to the routing node to a frequency F2 to enter a multicast receiving time slot to receive multicast messages, enters the unicast time slot after the routing node finishes the multicast sending time slot, and if a plurality of routing nodes on the same layer as the routing node are arranged on a topological structure, the frequency F2 of multicast sending of each routing node is different;
3) in the tree topology structure, a father node sends a multicast message in a multicast sending time slot, the father node enters a unicast time slot, a child node receives the multicast message in a multicast receiving time slot until a node farthest from a root node completes the unicast time slot, and one cycle is finished;
the whole network multicast process started by a non-root node comprises the following steps:
A. when the non-root node is a terminal node, the terminal node sends the multicast message to the associated routing node in a unicast time slot, namely a father node of the terminal node, the routing node multicasts the multicast message in a downlink direction in the multicast sending time slot, if the routing node has the father node, the routing node sends the multicast message to the father node in the unicast time slot, the father node continues multicasting in the downlink direction in the multicast sending time slot and sends the multicast message to the superior father node in the unicast time slot, the process continues until the superior father node, namely the root node receives the message and finishes the process of sending the multicast message to other routing nodes and terminal nodes associated with the root node;
B. when the non-root node is a routing node, the routing node needs to send multicast messages to the father routing node in the unicast time slot and starts downlink multicast in the multicast sending time slot, the father node which receives the multicast messages in the unicast time slot needs to send the multicast to the downlink and also sends the multicast messages to the father node of the routing node in the unicast time slot until the root node is reached, and the root node completes the process of sending the multicast messages by other associated routing nodes and terminal nodes.
2. The wireless ad hoc network management method based on time synchronization and frequency synchronization according to claim 1, wherein: the value of the frequency F2 is determined by the address of the node or the hierarchy of the topology in which the node resides.
3. The wireless ad hoc network management method based on time synchronization and frequency synchronization according to claim 1, wherein: the wireless self-organizing network management method based on time synchronization and frequency synchronization also comprises a communication method in a unicast time slot, and comprises the following steps:
a. all nodes listen in unicast time slots on a frequency F3, a communication initiator transmits a data request containing a communication destination node address and a communication frequency F4 on a frequency F3, then the communication initiator jumps to a communication frequency F4 to keep a receiving state, the communication frequency F4 is generated by the communication initiator in a random or designated manner before transmitting the data request, namely F4 is distinguished each time the data request is generated;
b. if the communication destination node successfully receives the data request and judges that the communication can be completed in the remaining time of the unicast time slot, jumping to a communication frequency F4, and then sending a prompt for the communication initiator to send data, wherein the communication initiator starts to send data after receiving the prompt;
c. after the communication initiator finishes sending data, if the communication initiator does not require confirmation, the communication is finished, and the communication initiator returns to the frequency F3; if the communication initiator requires to receive an acknowledgement, waiting for a period of time, acknowledging receipt, the communication being successful, if no acknowledgement is received, the communication failing, whether successful or not, the communication initiator returning to frequency F3; after that, if the communication fails, the communication initiator retries transmission at the next appropriate time on the frequency F3;
d. after waiting for a period of time at the communication frequency F4, if a prompt for the communication initiator to send data is not received from the communication destination node, the communication fails, and the communication initiator returns to the frequency F3 to wait for the next attempt;
e. the destination node goes to the communication frequency F4, waits for a period of time after sending a prompt for the originator to send data, and if no data is received, the destination node goes back to the frequency F3.
4. The wireless ad hoc network management method based on time synchronization and frequency synchronization according to claim 3, wherein: the root node is a gateway node.
5. The wireless ad hoc network management method based on time synchronization and frequency synchronization according to claim 4, wherein: the multicast receive slot of a child node is a slot that is synchronized with its associated parent node multicast transmit slot.
6. The wireless ad-hoc network management method based on time synchronization and frequency synchronization according to any one of claims 1 to 5, wherein: the unicast slot length of a parent node is equal to the unicast slot length of the parent node minus one multicast transmission slot of the parent node.
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| CN113452409B (en) * | 2021-06-24 | 2022-10-25 | 湖南基石通信技术有限公司 | Frequency hopping implementation method of asynchronous ad hoc network |
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