CN117769044A

CN117769044A - Quick networking method in hybrid multiple access mode

Info

Publication number: CN117769044A
Application number: CN202311719921.9A
Authority: CN
Inventors: 黄俊伟; 车锦贤; 汪磊; 刘怡豪; 王焱; 张大勇; 徐文浩
Original assignee: Chongqing University of Post and Telecommunications
Current assignee: Chongqing University of Post and Telecommunications
Priority date: 2023-12-14
Filing date: 2023-12-14
Publication date: 2024-03-26

Abstract

The invention relates to a rapid networking method in a hybrid multiple access mode, belonging to the technical field of communication networks. In the networking process of the central node, the central node constructs and transmits a beacon frame, receives and processes a network access request or a network access request summary message, allocates a beacon time slot for a new network access node, designates a proxy node, establishes route information, and resets a timer. In the networking process of the network-connected nodes, the nodes determine whether to adopt a network-connected request summarizing algorithm according to the role attribute and the networking state of the nodes, and the priority of the data frames is adjusted. The node receives and analyzes NECM or NECGM message, and queries the route table and forwards the message according to the destination address. And in the networking process of the nodes which are not connected with the network, the nodes monitor channels, and after the nodes finish monitoring, the nodes select father nodes and send NERM requests to connect with the network. If a valid TEI is received, the network is successfully joined, otherwise, joining other networks is attempted or the request is initiated again. The invention realizes the rapid networking in the hybrid multiple access mode.

Description

Quick networking method in hybrid multiple access mode

Technical Field

The invention belongs to the technical field of communication networks, and relates to a rapid networking method in a hybrid multiple access mode.

Background

The ad hoc network technology is a networking technology independent of network infrastructure such as switches, routers, base stations, etc. In the self-organizing network, each node can perceive the node which can directly communicate with itself through information exchange with surrounding nodes, and further realize communication among any nodes in the network in a multi-hop relay forwarding mode through a routing technology. Because the self-organizing network does not need to establish an infrastructure in advance and has the characteristic of autonomous organization, the self-organizing network is widely applied to the fields of industrial monitoring, environment monitoring, electricity consumption information acquisition and the like.

In order to meet the needs of different application scenarios, the ad hoc network may employ various network topologies. In the field of resource-constrained data information acquisition, tree topologies are widely adopted for their easy-to-manage, simple routing characteristics. In the tree topology network, a Central Node (CN) of the network serves as a root Node and is responsible for controlling the entire network. A typical tree topology network is shown in fig. 1.

In tree topology networks, one common networking scheme is beacon-based networking. The central node periodically transmits beacon frames, and causes the network-entered node to transmit the beacon frames. The non-network node senses network information and directly communicable network nodes by receiving beacon frames sent by the network nodes, and then selects one sensed network node as a parent node (Parentnode, PN) to which a message is sent in an attempt to join the network. The layer-by-layer triggering network access flow finally completes the establishment of the whole tree topology network.

In the networking scheme described above, the beacon frames are key to organizing the entire network. To guarantee the transceiving of the beacon frames, the beacon frames access the channel through the TDMA, thereby avoiding channel use collisions. And simultaneously, in order to avoid the waste of channel resources, the rest messages are accessed by adopting a CSMA mode. A specific channel usage scheme is shown in fig. 2. The TEI in fig. 2 is a terminal equipment identifier (Terminal Equipment Identifier) that is used to identify nodes within the network to facilitate communication addressing.

Although communication technologies have standardized networking schemes for such TDMA and CSMA hybrid multiple access coordinated beacons, there is room for improvement in specific practical implementations. In the networking process, the monitoring time of the non-networking node to the beacon frame directly influences the route convergence time and the topology stability of the network. Too long monitoring time can cause low networking efficiency of the network, which is unfavorable for timely communication and fault recovery of the network. Otherwise, the time period is too short, which may cause the non-network-connected node to ignore the high-quality relay node, so that the network connection relationship is unstable, topology fluctuation is generated, maintenance cost is increased, and communication reliability is reduced. In addition, when the network access node initiates the network access request, channel competition needs to be carried out with a maintenance message of the node in the network, and the time for the network access request message to enter the network is delayed. When a large number of nodes request to join the network, a large number of network access request messages are correspondingly generated in the system, so that the control overhead is increased. Because the network topology presents a tree structure, the messages are aggregated at the root node. Under a CSMA channel access mechanism, large-scale network access request behaviors can aggravate collision conditions near a root node, so that node forwarding processing burden is increased, data packet loss probability is improved, and networking time is prolonged.

Disclosure of Invention

Therefore, the present invention aims to provide a fast networking method in a hybrid multiple access mode, which solves the technical problems existing in the background technology by reasonably setting the monitoring time of the non-network-access stations, optimizing the forwarding processing flow of the network access request message and limiting the sending time of the maintenance message, thereby improving the networking efficiency and shortening the networking time of the network.

In order to achieve the above purpose, the present invention provides the following technical solutions:

a fast networking method under a hybrid multiple access mode comprises three processes of central node networking, networking of network-accessed nodes and networking of network-unaccessed nodes;

the central node networking comprises the following steps:

s11: the central node constructs and transmits a beacon frame, and a channel formulated by the central node propagates through the beacon frame by using a planning scheme; when the clock of the central node reaches the planned TDMA time slot, the central node occupies the first time slot to broadcast a beacon frame, and simultaneously starts a NETWORKING TIMER NETWORKING_TIMER for judging the NETWORKING state;

s12: the central node receives and processes a network access request message NERM or a network access request summary message NERGM;

s13: when a newly-accessed node exists, the center node allocates a beacon time slot of the newly-accessed node, a father node of the newly-accessed node is designated as an agent node, the beacon time slot of the agent node is positioned at the part of the TDMA time slot, the beacon time slots of the newly-accessed node are preferentially distributed, the center node establishes route information for the newly-accessed node, and a NETWORKING_TIMER is reset; when a new beacon period is started, the central node issues a whole network channel using scheme containing new beacon time slot planning through a beacon frame to trigger a new round of networking;

S14: when the central node network_timer overflows or the number of nodes in the network reaches a threshold value, completing network NETWORKING, and marking the NETWORKING mark position in the subsequent beacon frame as NETWORKING completion as follows: NETWROKING_COMPLETED;

the networking of the network-accessed nodes comprises the following steps:

s21: when the node receives the NERM, determining whether to adopt a network access request summarizing algorithm according to the role attribute and the networking state of the node; when the node receives the NERGM, forwarding the NERGM along a path to the central node directly;

when the NERM or NERGM is sent, the node adjusts the priority of the data frame according to the group network state;

when the node detects that the group network state is NETWORKING_IN_PROGRESS, setting the frame of the node bearing NERM and NERGM to be high priority;

when the node detects that the networking state is NETWROKING_COMPLETED, setting the frame of the node bearing NERM and NERGM as a general priority;

s22: the node receives and analyzes the message of NECM or NECGM, if the received message is a broadcast message, the node discards the message; if the node TEI is the last hop of the message, the node limits the received message to one hop for broadcasting; if the two conditions are not met, the node queries a routing table according to the final destination address, and forwards the message according to the routing table item; in the process of forwarding the message, a new routing table entry is added to the node, and the routing information from the current node to the node which successfully obtains the effective TEI is recorded; meanwhile, when the network is IN a NETWORKING state of NETWORKING_IN_PROGRESS, the node sets the frame bearing NECM or NECGM as high priority for forwarding;

S23: after receiving and analyzing the beacon frame, the node completes time synchronization, calculates the time slot of the beacon frame sent by the node, updates the stored network attribute and constructs the beacon frame of the node;

the networking of the non-network node comprises the following steps:

s31: the node MONITORs a channel, if the node receives an effective beacon frame for the first time, the node calculates the remaining time of the TDMA time slot of the network according to the time slot allocation information in the beacon frame, and sets and starts a MONITOR TIMER; the node keeps receiving the beacon frame;

the valid beacon frame is that the ALLOWED access flag bit of the beacon frame is indicated as allowed_entry, and the node does not mark that the attempt to join the network fails;

s32: the node finishes monitoring, selects a father node from the sending nodes of the received beacon frames according to the relay node selection strategy, adjusts the self time to synchronize with the NETWORK time, sends a NERM to the selected father node, and simultaneously starts a NETWORK access CONFIRMATION waiting TIMER NETWORK_ENTRY_CONFIRMATION_WAIT_TIMER to WAIT for the NETWORK access CONFIRMATION of the father node;

s33: the node receives the broadcast NECM or NECGM and analyzes the TEI value corresponding to the node; if the node acquires the effective TEI, the node successfully joins the network, converts the node into a network-entered node, records a father node, establishes a routing table to a central node, and starts a network maintenance flow; if the node acquires invalid_TEI, the node fails to join the network, and the node tries to join other networks; if the node does not receive the NECM/NECGM with its own MAC address and NETWORK_ENTRY_CONFIRMATION_WAIT_TIMER overflows during the NETWORK access acknowledgement, the node can attempt to join other NETWORKs or initiate a request to the NETWORK again.

Further, in S11, the field information of the beacon frame includes: network identifier, central node address, terminal equipment identifier, networking flag bit, allowed access flag bit, beacon time stamp, beacon period starting time, beacon period length, beacon time slot length, total number of beacons, total number of proxy nodes and beacon allocation information; the networking flag bit is marked as: NETWORKING_IN_PROGRESS, the allowed network entry flag bit indicates that joining is allowed, and is marked as: allowed_entry.

Further, in S12, the central node receives and processes the network access request message NERM or the network access request summary message NERGM, specifically:

the central node verifies the legality of the network access node in the network according to the received NERM or NERGM, for the verified node, the central node allocates the TEI for the verified node, for the unverified node, the central node does not record, allocates an invalid equipment identifier for the unverified node, and the invalid equipment identifier is recorded as follows: an invalid_tei for indicating that the node does not belong to the home network; the center node returns the TEI distributed to the node by using a network access confirmation message NECM and a network access confirmation summary message NECGM according to the original path; when the NETWORKING state is NETWORKING_IN_PROGRESS, NECM and NECGM adopt high-priority data frames to transmit.

Further, in S12, when the central node is a parent node of the network access request node, the central node responds by adopting NECGM, that is, when the central node receives multiple NERMs, the central node processes by adopting a network access request summarization algorithm of the network access node, and regards the received multiple NERMs as NERGM to process response.

Further, in the step S14, the threshold value of the number of nodes in the network is determined by the number of nodes in the white list by default, and the network completion indicates that the network-connected node does not execute the network-connection request summarizing algorithm and maintains the message sending time limiting mechanism, and the whole network does not send or forward the network-connection related message in a data frame with high priority; when the networking flag bit in the beacon frame received by the non-network node is: when the number of nodes in the network reaches a threshold value, the beacon frame allowed network access flag is marked as not allowed, and is marked as DENIED_ENTRY.

Further, in S21, when the node receives the NERM, it determines whether to use a network access request summarizing algorithm according to its role attribute and the networking state, specifically:

when the node is an agent node or the networking state is NETWROKING_COMPLETED, the node directly forwards NERM along a path to the central node, otherwise, the node adopts a network access request summarization algorithm to generate NERGM for reporting;

In the network access request summarizing algorithm, a network access request summarizing timer and a summarizing node quantity threshold value are introduced, and the network access request summarizing timer is recorded as: NETWORK_ENTRY_REQUEST_GATHER_TIMER; when (when)

The NETWORK_ENTRY_REQUEST_GATHER_TIMER overflows or the number of collected NERM reaches the threshold value of the number of summarized nodes, then the NERGM structure is completed, and a message reporting flow is entered;

the time length of the timer is set to reserve the time for the central node to return to NECGM in the cycle of the round of beacon;

the time length setting principle of the timer is expressed as follows:

T _reserved ＝α×RTT (2)

wherein,is the maximum value of the time length setting of the timer, T _current Is the current network time estimated by the node, T _reserved The reserved time, RTT is the round trip time estimated by the node to the central node, and is set according to the transceiving or history value of the beacon frame, and α is an adjustment coefficient.

Further, the network node periodically transmits maintenance messages, and decides whether to start a maintenance message transmission time limiting mechanism according to the roles and the states of the network node; in the mechanism, a CSMA time slot is divided into two time periods of maintenance message transmission limit and maintenance message transmission time; the node sends the maintenance message when the maintenance message is sent in the time period; the maintenance message sending limiting section consists of an absolute limit and a variable limit; the absolute limit is the minimum value of the maintenance message sending limit segment; the variable limit is judged by the node according to the state of the node; the mechanism node calculates the absolute limit time according to the following calculation formula:

T ^R ＝T _start +n _total ×T _beacon +T _{back_off} (3)

Wherein T is ^R Is the end time of the absolute limit, n _total Is the value of the total number of beacon slots in the beacon frame, T _{back_off} The size of the (C) is dependent on parameter setting of a CSMA/CA algorithm adopted by a system, and the maximum value of back-off when a message is sent is adopted by default;

when T is _current ≤T ^R When the message is in the queue, the maintenance message is queued in the transmission queue; after the absolute limit is finished, the node judges whether a network access request summarizing algorithm is started, and if the node is summarizing the network access request, the maintenance message of the node continues to be queued.

Further, in S23, the time slot of the beacon frame sent by the node itself is calculated, and the formula is as follows:

T _i ＝T _start +C _i ×T _beacon (4)

wherein T is _start Is the start time of the beacon period of the round, the value is the beacon period from the beacon framePhase start time field acquisition, C _i Is the count value of TEI from the first query to itself of the beacon allocation information in the beacon frame, T _beacon Is the value of the beacon slot length field in the beacon frame; when C _i ≤n _proxy When node i is indicated as a proxy node, n _proxy Is the total number of agent nodes in the beacon frame; node i is at T _i And transmitting own beacon frames at the moment.

Further, in S31, the remaining time of the TDMA time slot is calculated after the non-network node receives the beacon frame, and the calculation formula is expressed as:

Wherein,representing the monitoring duration of node j, C _i The node i that transmits the beacon frame counts in the slot allocation information.

Further, in the networking process of the non-networking node, after the end of the step S31, the non-networking node enters the step S32 before the absolute limit is ended; the node which is not connected with the network can still receive the beacon frame when S32 is carried out; information of the valid beacon frame is stored for the node replacement attempt target; after the node is successful in network access, redundant beacon frame information is cleared; the node fails to attempt to access the network, and directly enters S32 to attempt to join the new network without repeating S31 under the condition that other network information exists.

The invention has the beneficial effects that:

first, the network access process initiated by the non-network access node is quickened. The invention controls the monitoring time of the non-network node to the TDMA time slot of the joinable network through the channel monitoring mechanism based on the beacon information. Therefore, the selection space of the relay node can be ensured, and the overlong monitoring time is avoided. The invention also implements a maintenance message sending time limiting mechanism at the network edge, and simultaneously requires that the non-network-access node must enter a NERM sending flow before absolute limit is finished, so that interference of the maintenance message in the network to the non-network-access node for sending NERM is eliminated, and the network receives NERM as soon as possible. In addition, the invention distributes beacon time slots to the newly-accessed nodes preferentially at the central node, promotes the network discovery of the non-accessed nodes, and quickens the network access request initiation. Finally, aiming at the multi-network networking condition, the invention reserves the capability of the non-network node to receive and process other network beacons, and can directly start a new network attempt without re-monitoring channels when the network attempt fails.

Second, message propagation in the networking process is optimized. The invention introduces a network access request summarizing algorithm, so that the network access nodes at the network edge summarize NERM sent by a plurality of non-network access nodes, and the NERGM is used for transmitting in the network, thereby reducing message control overhead, reducing the probability of conflict caused by message uplink convergence, and relieving the forwarding processing pressure of the nodes. Meanwhile, the priority of the data frame is improved in the process of sending or forwarding the related message, and the capability of the message for preempting channels in CSMA time slots is enhanced.

Thirdly, intelligent adjustment of networking strategies is realized. When no new nodes are networked in a period of time or all nodes in the white list are added to the network, the system is considered to be free from the condition that a large number of nodes initiate networking. At this point, the network is already substantially formed and no more resources need to be devoted to networking. Therefore, the invention realizes the identification of the NETWORKING state by combining the NETWORKING_TIMER with the white list verification at the central node and informs the nodes of the whole network by using the beacon frame. In the network_complete state, the network access request summarization algorithm is not executed, and when a small number of nodes need to access the network, the connection with the central node can be established more quickly. Meanwhile, the sending priority of the related messages of the network access is restored in the state, and the message sending time limiting mechanism is closed, so that the network can better serve the service.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and other advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the specification.

Drawings

For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in the following preferred detail with reference to the accompanying drawings, in which:

fig. 1 is a diagram of a network topology

Fig. 2 is a schematic diagram of a channel usage scheme;

FIG. 3 is a flow chart of a process of a central node receiving an access request message;

FIG. 4 is a flow chart of a process of receiving an access request summary message by a central node;

FIG. 5 is a flow chart of NERM/NERGM reception processing of an already-network node;

FIG. 6 is a flowchart of a network request summarization algorithm;

FIG. 7 is a flow chart of NECM/NECGM reception process of an already-network node;

FIG. 8 is a schematic diagram of a channel usage scenario for maintaining a message transmission time restriction mechanism;

FIG. 9 is a flow chart of a maintenance message transmission of an already-network node;

FIG. 10 is a flowchart illustrating the implementation of a maintenance message sending time limit mechanism

Fig. 11 is a flow chart of channel monitoring for nodes not connected to the network

FIG. 12 is a message interaction flow diagram of a networking process;

FIG. 13 is a tree network topology of an embodiment;

FIG. 14 is a new channel usage plan for example 1;

FIG. 15 is a schematic diagram showing the behavior time sequence of nodes in embodiment 1;

FIG. 16 is a schematic diagram of the conversion of NERM to NERGM at node 4 in example 2;

FIG. 17 is a schematic diagram of a key behavior time sequence of a part of nodes in embodiment 2

Fig. 18 is a schematic diagram of the execution time sequence of the node 4, 5 maintenance message sending time limiting mechanism in embodiment 2.

Detailed Description

Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention. It should be noted that the illustrations provided in the following embodiments merely illustrate the basic idea of the present invention by way of illustration, and the following embodiments and features in the embodiments may be combined with each other without conflict.

Wherein the drawings are for illustrative purposes only and are shown in schematic, non-physical, and not intended to limit the invention; for the purpose of better illustrating embodiments of the invention, certain elements of the drawings may be omitted, enlarged or reduced and do not represent the size of the actual product; it will be appreciated by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numbers in the drawings of embodiments of the invention correspond to the same or similar components; in the description of the present invention, it should be understood that, if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc., that indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, it is only for convenience of describing the present invention and simplifying the description, but not for indicating or suggesting that the referred device or element must have a specific azimuth, be constructed and operated in a specific azimuth, so that the terms describing the positional relationship in the drawings are merely for exemplary illustration and should not be construed as limiting the present invention, and that the specific meaning of the above terms may be understood by those of ordinary skill in the art according to the specific circumstances.

Please refer to fig. 1-18, which illustrate a fast networking method in a hybrid multiple access mode.

The invention describes the networking process from three angles, namely a central node, a network-accessed node and a network-not accessed node.

The networking process of the central node is as follows:

step 1: the central node constructs and transmits beacon frames. The beacon frame should contain the field information IN table 1, where the NETWORKING flag bit indicates that NETWORKING is IN PROGRESS (denoted as networking_in_progress) and the allow-to-network flag bit indicates that joining is ALLOWED (denoted as allowed_entry). The channel usage plan established by the central node is also propagated through the beacon frames. When the central node clock reaches the planned TDMA time slot, the central node occupies the first time slot to broadcast a beacon frame. Simultaneously starting a NETWORKING TIMER (noted as networking_timer) for judging the NETWORKING state, wherein table 1 is a beacon frame necessary field information table;

TABLE 1

Step 2: the central node receives and processes the network access request message (Network Entry Request Message, NERM) or the network access request summary message (Network Entry Request Gather Message, NERGM). After receiving NERM or NERGM, the central node verifies the legality of the network node according to the white list. For nodes that pass the verification, the central node assigns a TEI to it. For nodes which do not pass verification, the central node does not record, and an invalid device identifier is allocated to the nodes, and the nodes are marked as: the invalid_tei is used to indicate that the node does not belong to the home network. The central node returns the TEI assigned to the node with a network entry confirmation message (Network Entry Confirmation Message, NECM) and a network entry confirmation summary message (Network Entry Confirmation Gather Message, NECM) along the original path. In the networking state of

NETWORKING_IN_PROGRESS, NECM and NECGM are transmitted using high priority data frames.

Step 3: in the case of a newly-networked node, the center node needs to allocate a beacon slot of the newly-networked node, and designate a parent node of the newly-networked node as a proxy node. The beacon slot of the proxy node must be guaranteed and located in the forward part of the TDMA slot. The beacon slots of the newly-accessed network nodes need to be arranged preferentially. In addition, the central node also needs to add routing information to the newly-entered node and reset network_timer. The process flow of the central node receiving the NERM and NERGM is shown in fig. 3 and 4, respectively. After the new beacon period is started, the central node issues a whole network channel using scheme containing new beacon time slot planning through a beacon frame to trigger a new networking process.

Step 4: the network NETWORKING is considered to be COMPLETED if the central node network_timer overflows or the number of nodes in the network reaches a threshold value, and the NETWORKING marker position in the subsequent beacon frame is NETWORKING completion (marked as network_complete). The threshold value of the number of nodes in the network is determined by the number of nodes in the white list by default and can be manually configured. The networking completion marks the end of the networking stage of the network, indicates that the network-connected node does not need to execute a network-connection request summarizing algorithm and a maintenance message sending time limiting mechanism, and the whole network does not need to send or forward network-connection related messages by using high-priority data frames. The non-network-connected node receives the beacon frame with the networking flag bit of NETWROKING_COMPLETED, and can still initiate a network-connection request. The number of nodes in the network reaches a threshold value, the beacon frame allowed access mark position is not allowed (marked as DENIED_ENTRY), and the network access confirmation summary report text table is shown in table 2;

TABLE 2

In the step 2, the NECGM message field is shown in Table 2. It is noted that the central node typically responds to NERM with NECM, which responds to NERGM, but when the central node is the parent node of the network access requesting node, the central node may respond with NECGM. In this special case, the central node needs to use the network access request summarization algorithm of the network access nodes, and treat the received multiple NERMs as NERGMs for processing responses.

The central node needs to perform network maintenance in the process of initiating networking, so that the network-connected nodes are ensured not to be disconnected.

The networking process of the network-accessed nodes is as follows:

step 1: the node receives and analyzes the beacon frame, completes time synchronization, calculates the time slot of the self-transmitted beacon frame, updates the stored network attribute and constructs the self-transmitted beacon frame.

T _i ＝T _start +C _i ×T _beacon (1)

The above formula is a formula for calculating self beacon transmission time by node i, wherein T _i Is the beacon transmission time of node i, T _start Is the start time of the beacon period of the round, the value is obtained from the beacon period start time field in the beacon frame, C _i Is the count value of TEI from the first query to itself of the beacon allocation information in the beacon frame, T _beacon Is the value of the beacon slot length field in the beacon frame. When C _i ≤n _proxy When node i is indicated as a proxy node, n _proxy Is the total number of proxy nodes in the beacon frame. Node i is at T _i And transmitting own beacon frames at the moment.

Step 2: the node receives NERM or NERGM, and the two messages correspond to different processing flows. The node receives NERM to decide whether to adopt the network access request summarization algorithm according to the attribute of the role and the networking state. When the node is a proxy node or the networking state is NETWROKING_COMPLETED, the node directly forwards NERM along a path to the central node. Otherwise, the node needs to adopt a network access request summarization algorithm to generate NERGM for reporting. The node receives the NERGM and forwards it directly along the path to the central node. The receiving flow of NERM and NERGM is shown in FIG. 5, and the flow of the network access request summarization algorithm is shown in FIG. 6. Table 3 provides field information for NERGM. When sending NERM or NERGM, the node needs to adjust the priority of the data frame according to the group network state. When the node detects that the NETWORKING state is NETWORKING_IN_PROGRESS, the node sets the frames carrying NERM and NERGM to high priority. In the case of NETWROKING_COMPLETED, then the frames carrying NERM and NERGM are set to a common priority, and Table 3 summarizes the message list for the network entry request.

TABLE 3 Table 3

Step 3: and receiving and analyzing NECM/NECGM, and discarding the broadcasted message if the node receives the broadcasted message. If the node TEI is the last hop of the message, the node limits the received message to one hop for broadcasting. If not, the node queries the routing table to forward the message according to the final destination address. In the case of no dropped message, it is also necessary to add the routing table entry to the node that successfully obtained the valid TEI at the present node. The specific flow of this step is shown in fig. 7. Similarly, when the NETWORKING state of the node is network_in_progress, the node sets the frame carrying the NECM or NECGM to be high priority for forwarding.

The above described request-for-access summarization algorithm introduces a request-for-access summarization timer (denoted as

Network_entry_request_gap_timer) and a summary node number threshold, which together determine to end the construction of a NETWORK. And when the number of NETWORK_ENTRY_REQUEST_GATHER overflows or the number of collected NERM reaches the threshold value of the number of summarized nodes, completing NERGM construction and entering a message reporting flow. The time length of the timer is set to reserve the time for the central node to return to NECGM in the cycle of the beacon.

T _reserved ＝α×RTT (3)

The above description describes the timer setting principle, Is the maximum value of the time length setting of the timer, T _current Is the current network time estimated by the node, T _reserved The reserved time, RTT is the round trip time estimated by the node to the central node, and can be set according to the transceiving or history value of the beacon frame, and α is an adjustment coefficient. The RTT is based on beacon frame evaluation, so that congestion retransmission and a central node processing process cannot be reflected, and the reserved time is amplified and ensured by adjusting the coefficient. The threshold value of the number of the summarization nodes can be configured by itself or calculated according to the capacity of a single MAC frame for bearing NECGM.

The above-mentioned process is the operation flow of the network-connected node participating in the networking process. In the actual networking scheme, the network maintenance of the network-connected node is also required, for example, a maintenance message is periodically sent to maintain the connection relationship of the adjacent nodes. The proxy node needs to collect the connection condition between the proxy node and the child node and report the connection condition to the central node.

In the network networking stage, the network-accessed node needs to decide whether to start a maintenance message sending time limiting mechanism according to the roles and states of the network-accessed node. In this mechanism, the network-entered node needs to reduce the CSMA slot resources available for maintenance messages. A specific channel usage scheme is shown in fig. 8. The figure shows that the CSMA slot is divided into two periods, where a node can only send a maintenance message for the period of time that the maintenance message is sent. And the maintenance message sending limiting section consists of an absolute limit and a variable limit. The absolute limit is the minimum value of the maintenance messaging limit segment. The variable restriction is determined by the node based on its own state.

After the mechanism is introduced, the flow of the maintenance message sent by the network node is shown in fig. 9. The mechanism requires the node to calculate the absolute limit time, and the calculation formula is as follows:

T ^R ＝T _start +n _total ×T _beacon +T _{back_off} (4)

wherein T is ^R Is the end time of the absolute limit, n _total Is the value of the total number of beacon slots in the beacon frame, T _{back_off} The size of the (C) is determined by the parameter setting of CSMA/CA algorithm adopted by the system, and the maximum value of back-off is adopted by default when the message is sent. When T is _current ≤T ^R When the maintenance message is needed to be queued in the transmit queue. After the absolute limit is finished, the node needs to determine whether the network access request summarizing algorithm is started. If the node is collecting network access requests at this time, the maintenance message of the node needs to continue queuing. The mechanism flow is shown in fig. 10.

The networking process of the non-network node is as follows:

step 1: the node listens to the channel. And if the beacon frame is received, extracting information. If a valid beacon frame is received for the first time, the end time of the TDMA time slot of the network is calculated, and a listening TIMER (denoted as monitor_timer) is set and started. The node remains to receive beacon frames. A valid beacon frame means that the ALLOWED access flag bit of the beacon frame indicates allowed_entry and the node does not flag an attempt to join the network failure.

The above is used to calculate TDMA time slot remaining time after a beacon frame is received by an uninteresting node,representing the monitoring duration of node j, C _i The node i that transmits the beacon frame counts in the slot allocation information. The channel listening flow is shown in fig. 11.

Step 2: and the node finishes monitoring, and selects a father node from the sending nodes of the received beacon frames according to the relay node selection strategy. The node synchronizes the time to the NETWORK and then sends a NERM to the selected parent node and starts a NETWORK ENTRY acknowledgement TIMER (denoted NETWORK_ENTRY_CONFIRMATION_WAIT_TIMER).

Step 3: and the node receives the broadcasted NECM/NECGM and analyzes the TEI value corresponding to the node. If the node acquires the effective TEI, the node is successful in network access, is converted into a network-accessed node, records a father node, establishes a routing table to a central node, and starts a network maintenance flow. If the node acquires an INVALID _ TEI, it marks that the attempt to join the network failed and attempts to join another network. If network_entry_configuration_wait_timer overflows, the node does not receive the NETWORK/NETWORK with its own MAC address, the node may attempt to join other NETWORKs or initiate a request to the NETWORK again.

After step 1 is finished, the non-network node should finish step 2 as soon as possible. The non-network-entry node must enter the NERM's transmission procedure before the absolute limit ends. The non-network node may still receive the beacon frame while proceeding to step 2. Information of valid beacon frames will be stored for node replacement attempt targets. And after the node is successful in network access, removing redundant beacon frame information. And the node network access attempt fails, and directly enters the step 2 to attempt to join a new network without repeating the step 1 under the condition of other network information.

Fig. 12 shows a message interaction flow of the networking process. It can be seen that the end of listening for a non-network-joining node is determined by receiving a beacon frame, thereby limiting the listening period to TDMA time slots of the network that are ready to attempt to join. The network access request summary can be used for converting a plurality of NERMs into one NERGM for reporting after waiting for a certain time.

In order to more clearly illustrate the application of the present invention in a practical scenario, a specific embodiment of the present invention will be given below. Fig. 13 is a specific tree network topology. For ease of description, FIG. 13 greatly simplifies the number of nodes. Correspondingly, the variable values used in the invention are correspondingly scaled. To further simplify the description, the node number in fig. 13 is taken as the TEI of each node in the embodiment, where node 1 is the center node.

Example 1: one layer node network access

This example illustrates the interaction flow in the networking process of the central node (node 1) and the non-network-connected nodes (node 2, node 3).

Step 1: after determining the channel usage scheme of the network, node 1 transmits a beacon frame in the first slot of the TDMA slots. The NETWORKING flag bit IN the beacon frame indicates networking_in_progress, and the ALLOWED NETWORKING flag bit indicates allowed_entry. And simultaneously, after the node 1 starts the NETWORKING stage, starting a NETWORKING_TIMER.

Step 2: node 2 and node 3 receive the beacon frame, parse the beacon frame, find that the NID is not marked and indicate that the network can be joined. Node 2 and node 3 calculate the listening time according to the beacon frame time slot related information, and turn on the respective monitor_timer. After monitor_timer overflows, node 2 and node 3 select node 1 as the parent node and synchronize time to the network. Node 2 and node 3 use CSMA/CA contention to use the channel and send the NERM to node 1.

Step 3: the node 2 can not be used for preempting channels, and the node 1 does not adopt a network access request summarizing algorithm. Node 1 receives the NERM of node 2 and node 3 in succession. After receiving the NERM of the node 2, the node 1 extracts the MAC address information and traverses and inquires the white list. After the MAC address of the node 2 is queried, the node 2 is allocated with TEI of 2, the NECM is broadcasted by adopting a frame with high priority, the node 2 is added in a routing table, the node 2 is allocated with a beacon time slot, and finally, the NETWORKING_TIMER is reset.

Step 4: both node 2 and node 3 receive the NECM of step 3 above. After node 2 resolves, it successfully obtains the TEI, and records the parent node as node 1. After the node 3 resolves, it finds that the MAC addresses do not match, and discards the packet.

Step 5: node 3 may not pass the white list verification, and node 1 may broadcast NECM after assigning it an INVALID invalid_tei.

Step 6: node 2 and node 3 receive the NECM of step 5. Node 2 is now the network node that has been entered and finds that the message is broadcast and drops directly. The node 3 resolves the invalid_tei, marks the current network as failed to attempt to join, and checks whether valid beacon frame information exists in itself. Node 3 finds out that there is no information available temporarily, node 3 re-enters the channel listening phase, waiting for a beacon frame of the new network.

Step 7: node 1 transmits a new beacon frame and issues a new slot plan through the beacon frame, and a new channel usage scheme is shown in fig. 14.

Step 8: after receiving the beacon frame, the node 2 analyzes the slot plan and sends the beacon frame in the corresponding slot. After receiving the beacon frame, node 3 finds that the network has been marked and discards the beacon frame.

The sequence of node behavior during a beacon period in the whole process is shown in fig. 15. After node 2 enters the network, the routing table of node 1 is shown in table 4.

TABLE 4 Table 4

Purpose TEI	Next hop TEI	Number of hops
			2	2	1

Example 2: three-layer node network access

This example illustrates the interaction flow of the non-network-connected nodes (node 7, node 8, node 9, node 10, node 11) and the network-connected nodes (node 2, node 3, node 4, node 5, node 6) in the networking process, and illustrates the operation of the maintenance message sending time limiting mechanism.

Step 1: the node 4 and the node 5 receive the beacon frame sent by the node 2, analyze the time slot arrangement in the beacon frame, and wait for the moment of sending the beacon frame by themselves respectively. Node 6 also receives the beacon frame of node 3 and takes the same steps. Node 4, node 5, node 6 send out beacon frames at corresponding time slots according to the time slot arrangement of the beacon frames.

Step 2: node 7, node 8, node 9 receive the beacon frames of node 4 and node 5 during the listening phase and node 10 and node 11 receive the beacon frames of node 6. Node 7 and node 8 select node 4, node 9 select node 5, node 10 and node 11 select node 6, and send NERM thereto, respectively, via their respective parent node selections.

Step 3: let alone node 4 first receives the NERM from node 7. Node 4 is not a proxy node at this point and the current round of beacon frames indicate network_in_progress, so node 4 begins executing the network entry request summarization algorithm. The threshold value of the total number of nodes is set to be 2, so that when node 4 receives NERM from node 8, node 4 completes construction of NERGM and sends NERGM to node 2. The peer node 6 issues a NERGM to node 3. Node 5 receives only one NERM, and needs to send NERGM node 4, node 5 and node 6 to node 2 after NETWORK_ENTRY_REQUEST_GATHER_TIMER overflows, and select high-priority data frames for use in NERGM transmission.

Step 4: node 2 forwards the NERGM from node 4 and node 5 to node 1 in succession, and node 3 operates the same. The forwarding process also uses high priority data frames.

Step 5: node 1 processes the NERGM in the order of reception, and node 11 may not pass the verification, node 2 forwards the NERGM of node 4 first, then the NERGM forwarded by node 3, and finally the NERGM forwarded by node 2 to node 5. In this process, the node 1 extracts node information in the NERGM one by one, and performs white list verification. For the processing of each node information, refer to step 3 in embodiment 1. When the NERGM is processed, the node 1 prepares the corresponding NECGM in advance, and then fills the required content of the NECGM in turn according to the processing condition of each node.

Step 6: the node 2 receives two NECGM in sequence, and the node 2 adds the route information to the node 7, the node 8 and the node 9. After receiving NECGM, node 3 adds routing information to node 10. And the node 2 and the node 3 query the routing table according to the final destination address of the frame bearing NECGM and forward the frame with high priority.

Step 7: the node 4 receives the corresponding NECGM first, after parsing, finds that the final destination address of the frame carrying the message is itself, the node 4 adds the routing information to the node 7 and the node 8, and then broadcasts the NECGM. At this time, due to the characteristic of the shared channel, the node 2 and the node 5 can also receive the message, and both of them are already connected to the network, and discard the message after receiving the broadcast type message. The following nodes 5, 6 take the same treatment scheme. The NECGM received by the node 6 indicates that the node 11 fails to access the network, and the node 6 only adds the routing information to the node 10.

Step 8: node 7, node 8, node 9 receive the NECGM broadcast by node 4 first. Node 7 and node 8 successfully resolve to TEI and successfully access the network. The node 9 cannot inquire about its own information through the NECGM and continues to wait. Node 7, node 8, node 9 receive the NECGM broadcast by node 5. The nodes 7 and 8 are already network-entered nodes, and discard the message. Node 9 resolves from it to TEI and completes the network entry. Node 10 and node 11 receive NECGM broadcast by node 6. Node 10 resolves to TEI and successfully joins the network. The node 11 resolves to invalid_tei, but fails to access the network and prepares to replace the network.

Fig. 16 depicts a message change diagram for the aggregation of network access requests at node 4. According to the embodiment, after the original 5 NERMs are summarized, only 3 messages need to be forwarded at the nodes 2 and 3 to reach the node 1. The advantage of this is apparent when tens or even hundreds of nodes request to join the network. Fig. 17 illustrates the behavior of nodes 4, 5, 7, 8 and 9 at some time during the network entry.

In step 3, if node 4 and node 5 are ready to send maintenance messages immediately after entering the CSMA slot. The node 4 detects that the network time is in an absolute limit phase and the maintenance message pauses to be sent. And when the node 4 finishes the absolute limit, the node is found that the node does not execute the network access request message summarizing algorithm, and the node 4 sends a maintenance message. Node 5, like node 4, pauses sending maintenance messages during the absolute limit phase. When node 5 has finished at the absolute limit, node 5 finds that the network access request summarization algorithm is being executed, and node 5 continues to wait for transmission. When NETWORK_ENTRY_REQUEST_GATHER_TIMER of the node 5 overflows, the node 5 sends out NERGM preferentially, and then sends out self maintenance message. The chronological order of the execution of this process is shown in fig. 18.

Example 3: networking policy adjustment

The example will describe the influence of the central node on the networking strategy by identifying the networking state, and by the networking flag bit and the allowed networking flag bit in the beacon frame.

It is assumed that when all the nodes of the first 3 layers in fig. 13 are connected to the network, the remaining nodes 12 are restarted due to a failure, and the nodes 13 cannot be connected to the network without receiving the beacon frame. In addition, if 11 nodes are included in the white list configured at the node 1 and the node 13 is not included, the following networking flow is provided:

step 1: node 1 overflows network_timer because it did not receive a successful network access request for a period of time. Node 1 schedules a new round of beacon frames in which the NETWORKING flag bit indicates network_complete.

Step 2: and each network-accessed node receives the beacon frame of each father node, analyzes the change of the networking state and updates the network attribute information. And then each network node which has entered sends out its own beacon frame according to the indication of the beacon frame.

Step 3: the node 12 receives the beacon frame of the node 7, and the same processing flows as in the embodiments 1 and 2, and finally sends out the NERM to the node 7.

Step 4: the node 7 receives the NERM, checks that the network attribute is NETWORKING_COMPLETED, and the node 7 directly forwards the NERM without summarizing. Along the path from node 7 to node 1, each node forwards the message in turn. The forwarding process uses data frames of generic priority.

Step 5: node 1 receives the network access request from node 12, as in the process flows of embodiments 1 and 2. In addition, after the white list verification is passed, the node 1 judges that all nodes in the white list are accessed to the network, updates the network attribute, and indicates the device_entry by the allowed access flag bit of the subsequent beacon frame.

Step 6: after successful network entry, node 12 waits for an indication of a new round of beacon frames. In a new cycle of beacon periods, node 12 updates the network attributes and transmits beacon frames in the corresponding time slots.

Step 7: after receiving the beacon frame of the node 12, the node 13 parses the beacon frame to the allowed access flag bit to indicate the device_entry, discards the beacon frame, and continues channel monitoring.

In this example, the node 1 controls the summarizing behavior of the network access request of the network-accessed node through the networking flag bit in the beacon frame, and informs the non-network-accessed node to give up trying to the network through the network access permission flag bit in the beacon frame.

Finally, it is noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the present invention, which is intended to be covered by the claims of the present invention.

Claims

1. A fast networking method under a hybrid multiple access mode is characterized in that: the method comprises three processes of central node networking, networking of network-accessed nodes and networking of network-not-accessed nodes;

the central node networking comprises the following steps:

s13: when a newly-accessed node exists, the center node allocates a beacon time slot of the newly-accessed node, a father node of the newly-accessed node is designated as an agent node, the beacon time slot of the agent node is positioned at the part of the TDMA time slot, the beacon time slots of the newly-accessed node are preferentially distributed, the center node establishes route information for the newly-accessed node, and a NETWORKING_TIMER is reset;

when a new beacon period is started, the central node issues a whole network channel using scheme containing new beacon time slot planning through a beacon frame to trigger a new round of networking;

the networking of the network-accessed nodes comprises the following steps:

the networking of the non-network node comprises the following steps:

2. The method for fast networking in a hybrid multiple access mode according to claim 1, wherein: in S11, the field information of the beacon frame includes: network identifier, central node address, terminal equipment identifier, networking flag bit, allowed access flag bit, beacon time stamp, beacon period starting time, beacon period length, beacon time slot length, total number of beacons, total number of proxy nodes and beacon allocation information; the networking flag bit is marked as: NETWORKING_IN_PROGRESS, the allowed network entry flag bit indicates that joining is allowed, and is marked as: allowed_entry.

3. The method for fast networking in a hybrid multiple access mode according to claim 2, wherein: in S12, the central node receives and processes the network access request message NERM or the network access request summary message NERGM, specifically:

4. A method for fast networking in a hybrid multiple access mode according to claim 3, wherein: in S12, when the central node is a parent node of the network access request node, the central node responds by adopting NECGM, that is, when the central node receives multiple NERMs, the central node processes by adopting a network access request summarization algorithm of the network access node, and regards the received multiple NERMs as NERGM to process the response.

5. The method for fast networking in a hybrid multiple access mode according to claim 4, wherein: in the step S14, the threshold value of the number of nodes in the network is determined by the number of nodes in the white list by default, and the network completion indicates that the network-connected nodes do not execute the network-connection request summarizing algorithm and maintain the message sending time limiting mechanism, and the whole network does not send or forward the network-connection related message in a high-priority data frame; when the networking flag bit in the beacon frame received by the non-network node is:

when the number of nodes in the network reaches a threshold value, the beacon frame allowed network access flag is marked as not allowed, and is marked as DENIED_ENTRY.

6. The method for fast networking in a hybrid multiple access mode according to claim 5, wherein: in S21, when the node receives the NERM, it determines whether to adopt a network access request summarizing algorithm according to its role attribute and the networking state, specifically:

in the network access request summarizing algorithm, a network access request summarizing timer and a summarizing node quantity threshold value are introduced, and the network access request summarizing timer is recorded as: NETWORK_ENTRY_REQUEST_GATHER_TIMER; when the number of NETWORK_ENTRY_REQUEST_GATHER_TIMER overflows or the number of collected NERM reaches the threshold value of the number of summarized nodes, completing NERGM construction, and entering a message reporting flow;

the time length setting principle of the timer is expressed as follows:

T _reserved ＝α×RTT (2)

7. The method for fast networking in a hybrid multiple access mode according to claim 6, wherein:

periodically sending maintenance messages by the network node, and determining whether to start a maintenance message sending time limiting mechanism according to the roles and the states of the network node; in the mechanism, a CSMA time slot is divided into two time periods of maintenance message transmission limit and maintenance message transmission time; the node sends the maintenance message when the maintenance message is sent in the time period; the maintenance message sending limiting section consists of an absolute limit and a variable limit; the absolute limit is the minimum value of the maintenance message sending limit segment; the variable limit is judged by the node according to the state of the node; the mechanism node calculates the absolute limit time according to the following calculation formula:

T ^R ＝T _start +n _total ×T _beacon +T _{back_off} (3)

8. The method for fast networking in a hybrid multiple access mode according to claim 7, wherein: in S23, the time slot of the beacon frame sent by the node is calculated, where the formula is:

T _i ＝T _statc +C _i ×T _beacon (4)

wherein T is _start Is the start time of the beacon period of the round, the value is obtained from the beacon period start time field in the beacon frame, C _i Is the count value of TEI from the first query to itself of the beacon allocation information in the beacon frame, T _beacon Is the value of the beacon slot length field in the beacon frame; when C _i ≤n _proxy When node i is indicated as a proxy node, n _proxy Is the total number of agent nodes in the beacon frame; node i is at T _i And transmitting own beacon frames at the moment.

9. The method for fast networking in a hybrid multiple access mode according to claim 8, wherein: in S31, the remaining time of the TDMA time slot is calculated after the non-network node receives the beacon frame, and the calculation formula is expressed as:

10. The method for fast networking in a hybrid multiple access mode according to claim 9, wherein: in the networking process of the non-networking nodes, after S31 is finished, the non-networking nodes enter S32 before absolute limit is finished; the node which is not connected with the network can still receive the beacon frame when S32 is carried out; information of the valid beacon frame is stored for the node replacement attempt target; after the node is successful in network access, redundant beacon frame information is cleared; the node fails to attempt to access the network, and directly enters S32 to attempt to join the new network without repeating S31 under the condition that other network information exists.