TDMA ad hoc network access method and system based on dynamic time slot frame structure

Abstract

The invention discloses a TDMA (Time Division Multiple Access) ad hoc network access method based on a dynamic time slot frame structure, which comprises the following steps: on the basis of networking in a fixed TDMA mode, interacting an on-line node mapping table and an off-line node mapping table through signaling to obtain the number of on-line nodes and node IDs (Identity) of the whole network so as to adjust the design of an on-network time slot frame structure, reduce the occupation of useless time slot resources and improve the access efficiency of the whole network. The frame efficiency is effectively improved, and the service transmission quality is improved. According to the method, the time slot frame structure can be adjusted according to the number of online nodes, the node information is notified to the whole network in a mapping table mode, the signaling overhead is reduced, the method adapts to different network scale scenes through the access mode of the dynamic time slot frame structure, and the service transmission quality is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of wireless communication, and in particular to a TDMA self-organizing network access method and system based on a dynamic time slot frame structure. Background Technology

[0002] The essence of MAC protocols is to study how to effectively utilize wireless spectrum and avoid competition and conflicts when ad hoc network nodes share spectrum resources. In traditional wireless ad hoc network communication, MAC layer access mostly adopts contention-based access (CSMA / CA) and fixed TDMA access methods. The CSMA / CA protocol accesses the channel on demand, and each node in the network listens to the wireless channel and sends data packets according to the channel's busy / idle status. This protocol has problems such as hiding and exposing terminals, increased traffic load, increased packet collision rate, insufficient channel utilization, and increased network latency due to nodes attempting to backoff multiple times.

[0003] The strategy based on fixed TDMA access involves allocating time slots for nodes in the network, with each node operating only within its assigned time slot, thus avoiding data packet collisions. However, this can lead to wasted time slots under low traffic loads, resulting in lower throughput and higher latency.

[0004] Therefore, there is an urgent need for a TDMA access method that adaptively adjusts the time slot frame structure to improve the quality of service transmission. Summary of the Invention

[0005] Purpose of the invention: To address the problems existing in the prior art, this invention proposes a TDMA self-organizing network access method based on a dynamic time slot frame structure. The signaling interaction cycle time is adaptively adjusted according to the new time slot frame structure, thereby reducing the access delay of late-entry nodes and the service transmission delay.

[0006] Technical solution:

[0007] This invention proposes a TDMA self-organizing network access method based on a dynamic time-slot frame structure, comprising:

[0008] S1: The self-organizing network node accesses the network system in TDMA mode, determines the number of rows and columns of the networking time slot frame structure according to the maximum number of nodes supported by the network system, switches the self-organizing network node to the networking time slot frame structure and initializes it;

[0009] S2: Design an online time slot frame structure, including signaling time slots and contention time slots; the self-organizing network node completes network time synchronization, switches to the online time slot frame structure, and becomes an online node. Each online node locally maintains an online node mapping table and an offline node mapping table.

[0010] S3: Each online node receives / sends signaling messages in the signaling time slot and announces them to the entire network through the signaling channel until the online mapping tables of all online nodes are unified;

[0011] S4: Obtain the number of online nodes at the current time from the online mapping table, and dynamically update the online time slot frame structure;

[0012] S5: Nodes that join the network system later are regarded as late-entry nodes. The late-entry nodes complete time synchronization with the online nodes and switch to the online time slot frame structure to achieve network entry.

[0013] S6: When any online node becomes an offline node, the one-hop neighbor node of the offline node updates the node ID of the offline node to the local offline node mapping table of the one-hop neighbor node, and synchronizes the update of the local offline node mapping table to the offline node mapping tables of all online nodes through signaling messages, and updates the time slot frame structure accordingly.

[0014] S7: Based on the determined time slot frame structure, update the contention time slot and complete the service transmission and reception process.

[0015] Furthermore, step S1 also includes: the initialization includes initializing all time slots in the network time slot frame structure as the corresponding node's transmit / receive time slots, and each network node transmits / receives synchronization information in the corresponding transmit / receive time slot to complete time synchronization.

[0016] Furthermore, the signaling message includes an online node mapping table and an offline node mapping table of the online node that sent the signaling message; the online node that receives the signaling message performs interactive calculations based on the signaling message and updates its local online node mapping table.

[0017] Furthermore, step S3 also includes:

[0018] S3.1: Define the frame length, superframe, and beat of the time slot frame structure. Odd beats are used for access, and even beats are used for interaction.

[0019] S3.2: After an even-numbered beat begins, the online node performs an OR operation between its local online node mapping table and the online node mapping table received in the previous even-numbered beat to form a new local online node mapping table.

[0020] S3.3: In even-numbered beats, a node announces its local online node mapping table to all one-hop neighbor nodes via signaling;

[0021] S3.4: After receiving the signaling message, the one-hop neighbor node parses the online node mapping table in it, performs an OR operation between the online node mapping table and the local online node mapping table to form a new local online node mapping table;

[0022] S3.5: Repeat steps S3.3 and S3.4 until the beat ends;

[0023] S3.6: After an even-numbered beat ends, all online nodes in the network have the same local online node mapping table, and the new frame structure is calculated from the start of an odd-numbered beat.

[0024] Furthermore, step S4 also includes:

[0025] During odd-numbered beats, the current number of online nodes and the online node ID are obtained from the online node mapping table; the time slot resources occupied by the online nodes are retained in the online time slot frame structure, the time slot resources occupied by offline nodes are deleted, and several access time slots are added for late-entry nodes to access the network in step S5.

[0026] Furthermore, step S5 also includes:

[0027] S5.1: The late-entry node listens to the signaling messages of the online nodes to obtain the synchronization time and the number of online nodes, and determines the time slot frame structure that is the same as the time slot frame structure obtained in step S4;

[0028] S5.2: If a node is in an odd-numbered clock cycle, the late-entering node sends signaling messages in two access time slots. If it is in an even-numbered clock cycle, the access procedure is not started. The node waits for the odd-numbered clock cycle to arrive before starting the access procedure.

[0029] S5.3: During odd-numbered clock cycles, late-entering nodes will set their own position in the online node mapping table to 1 in the signaling messages they send.

[0030] S5.4: After receiving the signaling message from the late-entering node, the neighboring node records the online node mapping table in the signaling message, waits for the even-numbered beat to arrive, and then broadcasts the late-entering node information to the entire network.

[0031] S5.5: During even-numbered beats, late-entering nodes listen to the signaling messages of online nodes and check whether their own online node mapping table is included in the neighboring nodes' online node mapping table. If it is included, the late-entering node enters the network.

[0032] S5.6: After a late-entering node joins the network, wait for the odd-numbered beats to begin before proceeding to step S6; if the late-entering node fails to join the network, repeat steps S5.2 to S5.5.

[0033] Furthermore, the criteria for determining whether an online node becomes an offline node include:

[0034] The routing module of the network system determines whether a node is offline. When the routing timer exceeds the routing aging time, the node is considered offline.

[0035] Furthermore, step S6 also includes:

[0036] S6.1: At the start of an even-numbered beat, online nodes place offline nodes in the offline node mapping table and broadcast the offline node mapping table to the entire network in the signaling.

[0037] S6.2: After receiving the signaling message, the one-hop neighbor node performs a bitwise AND operation with the local offline node mapping table to form a new local offline node mapping table;

[0038] S6.3: A one-hop neighbor node broadcasts the new offline node mapping table to its multi-hop neighbors. In even-numbered beats, the local online node mapping table and the local offline node mapping table of all online nodes in the network are the same.

[0039] S6.4: At the start of an odd-numbered beat, each online node calculates the nodes to be excluded from the local offline node mapping table from the local online node mapping table;

[0040] S6.5: Based on the new online node mapping table, perform the steps of S4 to update the online time slot frame structure.

[0041] On the other hand, the present invention also proposes a TDMA self-organizing network access system based on a dynamic time slot frame structure, including a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of any of the aforementioned methods.

[0042] On the other hand, the present invention also proposes a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any of the aforementioned methods.

[0043] Beneficial effects:

[0044] In this invention, self-organizing network nodes obtain online node information, offline node information, and dynamic time slot allocation information of the entire network through interactive signaling information. The online node information and offline node information are transmitted through a mapping table, which effectively reduces signaling overhead. The low-speed control channel transmits signaling, which improves the reliability of signaling interaction.

[0045] By statistically analyzing two mapping tables, the number of online nodes and their IDs are calculated, thereby adjusting the on-network time slot frame structure. This involves clearing signaling time slots occupied by offline nodes and reserving service time slots, effectively improving frame efficiency. Simultaneously, the optimized frame structure reduces the signaling transmission cycle of each node, lowering the interaction latency of dynamic time slot allocation information and improving service transmission quality.

[0046] Late-entry nodes can quickly join the network due to the optimization of the signaling transmission cycle. This invention uses a dynamic time-slot frame structure access method to shorten the signaling interaction cycle and reduce the interaction time of synchronization information, data time slot allocation information, etc., thus solving the problems of slow late-entry and low service transmission efficiency in the prior art. Furthermore, the dynamic time-slot frame structure access method of this application is only related to the number of online nodes and can adapt to the access of self-organizing networks of different network sizes. Attached Figure Description

[0047] Figure 1 This is a flowchart of a TDMA self-organizing network access method based on a dynamic time slot frame structure according to the present invention;

[0048] Figure 2 A schematic diagram of initializing the network time slot frame structure and the on-network time slot frame structure for self-organizing network nodes;

[0049] Figure 3 This is a schematic diagram of the signaling frame structure;

[0050] Figure 4 For online node mapping table;

[0051] Figure 5 This is a diagram showing the updated online time slot frame structure of the online nodes.

[0052] Figure 6 This is an offline node mapping table. Detailed Implementation

[0053] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0054] like Figure 1 The diagram shows a flowchart of a TDMA self-organizing network access method based on a dynamic time-slot frame structure according to the present invention. The steps include network formation, signaling interaction, updating the online node mapping table, updating the time-slot frame structure, late node entry into the network, node disconnection from the network, and service provision. Details are as follows:

[0055] Step 1: Network setup.

[0056] The self-organizing network adopts a time-division multiplexing (TDMA) access system, meaning that the transmission and reception of each node are separated on the time axis, such as... Figure 2 The left side shows the initial network setup time slot frame structure of this embodiment. Each small square is 4ms, defined as one time slot (subframe). The maximum network capacity is no less than 32 nodes (32 rows and 4 columns in the frame structure, configurable according to business needs). The frame length is the sum of all time slots, 512ms. (The text continues with further details about the structure and its configuration.) Figure 2 In the 512ms time slot shown on the left, each node allocates four fixed time slots for transmission and configures reception in the remaining time slots. A master station is configured in the network, and other nodes are configured as slave stations. The slave stations synchronize with the master station through the exchange of synchronization information, thus completing the network configuration.

[0057] Step 2: Signaling interaction.

[0058] After the self-organizing nodes complete the network formation in step 1, they switch to the online state at the same time. The time slot frame structure changes from the network formation time slot frame structure (at this time, the initial network establishment time slot frame structure) to the online time slot frame structure. The online time slot frame structure consists of signaling time slots, reserved time slots, and contention time slots, as shown below. Figure 2 The initialization frame structure shown on the right is the network time slot frame structure. Low-speed signaling time slots are used for signaling interaction. Signaling information mainly includes synchronization information, online and offline node information, and contention for time slot allocation, etc. The signaling frame structure in this embodiment is as follows: Figure 3 As shown.

[0059] Step 3: Update the online node mapping table.

[0060] Define a time-slot frame structure with a frame length of one superframe, and one beat as 10 superframes. Odd beats are used for access, and even beats are used for interaction. The specific steps include the following:

[0061] 3.1: After an even-numbered beat begins, the ad hoc network node performs a bitwise OR operation between its local online node mapping table and the online node mapping table received in the previous beat to form a new local online node mapping table, such as 1001. 0100 = 1101. The updated online node mapping table is as follows: Figure 4 As shown, the node number corresponds to the node bit, where 1 indicates the node is online and 0 indicates the node is offline.

[0062] 3.2: During even-numbered beats, the node announces its local online node mapping table to all 1-hop neighbor nodes via signaling. The 1-hop neighbor nodes are those within the node's 1-hop communication range.

[0063] 3.3: After receiving the signaling, the 1-hop neighbor node parses the online node mapping table, performs an OR operation between the neighbor node's online node mapping table and the local online node mapping table, and forms a new local online node mapping table.

[0064] 3.4: Repeat steps 3.2 and 3.3 until the beat ends.

[0065] 3.5: After an even-numbered beat ends, the local online node mapping tables of all ad hoc network nodes are identical. At the beginning of an odd-numbered beat (subframe number 0), the calculation of the new frame structure begins.

[0066] Step 4: Update the time slot frame structure.

[0067] During odd-numbered beats, the number of online nodes and their IDs are obtained from the online node mapping table. The updated online node time-slot frame structure is as follows: Figure 5 As shown, after an even-numbered cycle of interaction, the entire network is aware that nodes 6, 9, 12, and 20 are online. To allow other nodes to join the network later, two access time slots are added. These access time slots are used for newly joined nodes to send signaling, and online nodes are always configured to receive during these slots. After the time slot frame structure is updated, the frame length is shortened from 512ms to 80ms, significantly reducing signaling interaction time and service transmission latency.

[0068] Step 5: Late-entry nodes join the network.

[0069] Nodes joining the network system later are considered late-entry nodes. Late-entry nodes are also nodes preparing to join the network, similar in nature to the networking nodes in step 1. The difference is that late-entry nodes join a network to receive signaling information from an existing node. Networking nodes, on the other hand, form a network with other nodes and synchronize with the master node. Configure the late-entry nodes with their network attributes as per step 1, specifically including the following sub-steps:

[0070] 5.1: Late-entry nodes listen to the signaling of online nodes to obtain information such as synchronization time and number of online nodes, calculate the superframe number and subframe number of the network, and determine the time slot frame structure.

[0071] 5.2: If a node is in an odd-numbered clock cycle, the late-entering node sends signaling in two access time slots. If it is in an even-numbered clock cycle, the access procedure is not initiated. The node waits for the odd-numbered clock cycle to arrive before initiating the access procedure.

[0072] 5.3: During odd-numbered beats, late-entering nodes will set their own position in the online node mapping table to 1 in the signaling information they send.

[0073] 5.4: After receiving the signaling from the late-entry node, the neighboring node records the online node mapping table in the signaling and waits for the even-numbered beat to arrive before broadcasting the late-entry information to the entire network.

[0074] 5.5: During even-numbered beats, late-entry nodes listen to the signaling of online nodes and check whether their own online node mapping table is included in the neighboring nodes' online node mapping table. If it is included, it means that the late-entry is successful.

[0075] 5.6: After successful late network access, wait for the odd-numbered clock cycle to begin, calculate the new frame structure, and initiate network services. If late network access fails, repeat steps 5.2 to 5.5.

[0076] Step 6: Node disconnects from network.

[0077] The routing module determines whether a node is offline. When the routing timer exceeds the routing aging time, the node is determined to be offline (disconnected from the network), and its neighboring nodes remove the node from the online node mapping table. Specifically, this includes the following sub-steps:

[0078] 6.1: At the start of an even-numbered beat, nodes that meet the offline exit condition are placed in the offline node mapping table, i.e., the corresponding bit in the offline node mapping table is set to 1, such as... Figure 6 As shown, the offline node mapping table is broadcast to the entire network in the signaling.

[0079] 6.2: After receiving the signaling, the neighboring node performs a bitwise AND operation with the local offline node mapping table to form a new local offline node mapping table.

[0080] 6.3: Neighboring nodes broadcast the new offline node mapping table to multi-hop neighbors. During even-numbered beats, the local online node mapping table and the local offline node mapping table of all nodes in the network are the same.

[0081] 6.4: At the start of an odd-numbered beat, each node calculates a new local online node mapping table, represented as:

[0082]

[0083] Where - is the exclusion operator, AB means removing elements contained in set B from set A, for example 1101-0100 =1001.

[0084] 6.5: Update the time slot frame structure of online nodes according to the new online node mapping table.

[0085] Step 7: Business Implementation.

[0086] In the new frame structure, data competition for time slot updates during service transmission is conducted to complete service transmission and reception.

Claims

1. A TDMA self-organizing network access method based on a dynamic time-slot frame structure, characterized in that, include: S1: The self-organizing network node accesses the network system in TDMA mode, determines the number of rows and columns of the networking time slot frame structure according to the maximum number of nodes supported by the network system, switches the self-organizing network node to the networking time slot frame structure and initializes it; S2: Design an online time slot frame structure, including signaling time slots and contention time slots; the self-organizing network node completes network time synchronization, switches to the online time slot frame structure, and becomes an online node. Each online node locally maintains an online node mapping table and an offline node mapping table. S3: Each online node receives / sends signaling messages in the signaling time slot and announces them to the entire network through the signaling channel until the online mapping tables of all online nodes are unified; S4: Obtain the number of online nodes at the current time from the online mapping table, and dynamically update the online time slot frame structure; S5: Nodes that join the network system later are regarded as late-entry nodes. The late-entry nodes complete time synchronization with the online nodes and switch to the online time slot frame structure to achieve network entry. S6: When any online node becomes an offline node, the one-hop neighbor node of the offline node updates the node ID of the offline node to the local offline node mapping table of the one-hop neighbor node, and synchronizes the update of the local offline node mapping table to the offline node mapping tables of all online nodes through signaling messages, and updates the time slot frame structure accordingly. S7: Based on the determined time slot frame structure, update the contention time slot and complete the service transmission and reception process.

2. The self-organizing network access method according to claim 1, characterized in that, Step S1 further includes: the initialization includes initializing all time slots in the network time slot frame structure as the corresponding node's transmit / receive time slots, and each network node transmits / receives synchronization information in the corresponding transmit / receive time slot to complete time synchronization.

3. The self-organizing network access method according to claim 2, characterized in that, The signaling message includes an online node mapping table and an offline node mapping table of the online node that sent the signaling message; the online node that receives the signaling message performs interactive calculations based on the signaling message and updates its local online node mapping table.

4. The self-organizing network access method according to claim 3, characterized in that, Step S3 further includes: S3.1: Define the frame length, superframe, and beat of the time slot frame structure. Odd beats are used for access, and even beats are used for interaction. S3.2: After an even-numbered beat begins, the online node performs an OR operation between its local online node mapping table and the online node mapping table received in the previous even-numbered beat to form a new local online node mapping table. S3.3: In even-numbered beats, a node announces its local online node mapping table to all one-hop neighbor nodes via signaling; S3.4: After receiving the signaling message, the one-hop neighbor node parses the online node mapping table in it, performs an OR operation between the online node mapping table and the local online node mapping table to form a new local online node mapping table; S3.5: Repeat steps S3.3 and S3.4 until the beat ends; S3.6: After an even-numbered beat ends, all online nodes in the network have the same local online node mapping table, and the new frame structure is calculated from the start of an odd-numbered beat.

5. The self-organizing network access method according to claim 4, characterized in that, Step S4 further includes: During odd-numbered beats, the current number of online nodes and the online node ID are obtained from the online node mapping table; the time slot resources occupied by the online nodes are retained in the online time slot frame structure, the time slot resources occupied by offline nodes are deleted, and several access time slots are added for late-entry nodes to access the network in step S5.

6. The self-organizing network access method according to claim 5, characterized in that, Step S5 further includes: S5.1: The late-entry node listens to the signaling messages of the online nodes to obtain the synchronization time and the number of online nodes, and determines the time slot frame structure that is the same as the time slot frame structure obtained in step S4; S5.2: If a node is in an odd-numbered clock cycle, the late-entering node sends signaling messages in two access time slots. If it is in an even-numbered clock cycle, the access procedure is not started. The node waits for the odd-numbered clock cycle to arrive before starting the access procedure. S5.3: During odd-numbered clock cycles, late-entering nodes will set their own position in the online node mapping table to 1 in the signaling messages they send. S5.4: After receiving the signaling message from the late-entering node, the neighboring node records the online node mapping table in the signaling message, waits for the even-numbered beat to arrive, and then broadcasts the late-entering node information to the entire network. S5.5: During even-numbered beats, late-entering nodes listen to the signaling messages of online nodes and check whether their own online node mapping table is included in the neighboring nodes' online node mapping table. If it is included, the late-entering node enters the network. S5.6: After a late-entering node joins the network, wait for the odd-numbered beats to begin before proceeding to step S6; if the late-entering node fails to join the network, repeat steps S5.2 to S5.

5.

7. The self-organizing network access method according to claim 6, characterized in that, The criteria for determining whether an online node becomes an offline node include: judging whether a node is offline based on the routing module of the network system; when the routing timer exceeds the routing aging time, the node is determined to be offline.

8. The self-organizing network access method according to claim 7, characterized in that, Step S6 further includes: S6.1: At the start of an even-numbered beat, online nodes place offline nodes in the offline node mapping table and broadcast the offline node mapping table to the entire network in the signaling. S6.2: After receiving the signaling message, the one-hop neighbor node performs a bitwise AND operation with the local offline node mapping table to form a new local offline node mapping table; S6.3: A one-hop neighbor node broadcasts the new offline node mapping table to its multi-hop neighbors. In even-numbered beats, the local online node mapping table and the local offline node mapping table of all online nodes in the network are the same. S6.4: At the start of an odd-numbered beat, each online node calculates the nodes to be excluded from the local offline node mapping table from the local online node mapping table; S6.5: Based on the new online node mapping table, perform the steps of S4 to update the online time slot frame structure.

9. A TDMA self-organizing network access system based on a dynamic time-slot frame structure, comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of any of the methods of claims 1 to 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of any of the methods described in claims 1 to 8.

Images