A hybrid channel allocation method for wireless ad hoc networks

Abstract

The present invention relates to a hybrid channel allocation method applicable to wireless self-organizing networks in the field of wireless self-organizing networks, and is particularly applicable to wireless self-organizing network environments that adopt a time division multiple access (TDMA) mechanism. First, the network cluster head node centrally allocates dedicated channels for newly connected nodes, which can ensure the reliable transmission of time-sensitive services of each node; at the same time, considering that the dedicated channel of each node has the characteristic of being spatially reused by nodes beyond two hops, a mechanism for locally maintaining a shared channel list is designed, and a mechanism for competing to occupy a shared channel on a reserved channel is proposed, which can avoid collisions caused by reservation message conflicts and reduce the number of information interactions in competing for a shared channel, ultimately meeting the large-capacity data transmission needs of each node. The hybrid channel allocation method of the present invention makes full use of all channel resources of the network, is simple and easy to implement, and can effectively improve the transmission capacity of the entire network.

Description

Technical Field

[0001] The present invention relates to a hybrid channel allocation method applicable to wireless self-organizing networks in the field of wireless self-organizing networks, and is particularly suitable for wireless self-organizing network environments that adopt a time division multiple access (TDMA) mechanism. The method ensures the transmission of signaling and time-sensitive services of each node by centrally allocating dedicated channels, improves the utilization rate of channel resources by distributed competitive sharing of channels, and can achieve reliable transmission of services of each node in the network and overall improvement of the transmission capacity of the entire network. Background Art

[0002] A wireless ad hoc network is an infrastructure-free wireless mobile communication network comprised of multiple nodes with wireless transceiver capabilities. Due to the limited transmit power of each node, its transmission range is limited. When direct communication between nodes is impossible, relaying is required between other nodes in the network. Therefore, a wireless ad hoc network is also a wireless multi-hop communication network. Because a wireless ad hoc network lacks infrastructure such as base stations, nodes in the network require distributed interaction to communicate signaling messages such as access control, routing tables, and time synchronization, as well as service messages, to achieve networking and transmission. Furthermore, all nodes in the network share wireless channels, and each node can obtain network access and channel resource usage rights based on specific policies.

[0003] In wireless ad hoc networks, how to allocate dedicated channel resources to each node while maximizing resource utilization across the entire network is a problem worthy of in-depth study. Zhu et al. proposed a classic five-phase time slot reservation protocol in IEEE INFOCOM, 1998, Vol. 1, 322-331: "A five-phase reservation protocol (FPRP) for mobile ad hoc networks." This protocol can effectively adapt to topology changes, but all nodes compete for the same set of channels, resulting in a high probability of contention conflicts. Masilamani et al. proposed a distributed time slot allocation mechanism based on virtual coordinates of node relative positions in Univ. of California, 2012, 1-6: "VCMA: Efficient channel access in wireless mesh networks using virtual coordinates." This mechanism can reduce information exchange and negotiation between nodes, but relies on a dedicated public control channel in the system. Once this dedicated public control channel is interfered with, it can paralyze the entire network. Prihadi et al. proposed a channel allocation mechanism based on end-to-end connections in APCC 2016, 535-540: "A multi-channel MAC for multi-hop wireless sensor networks minimizing hidden node collision." This mechanism can improve channel utilization to a certain extent. However, in actual wireless ad hoc networks, the destination node of a node's service data is unknown and variable before it competes for channel resources and during service transmission, which limits the applicability of this method. Summary of the Invention

[0004] The present invention aims to propose a hybrid channel allocation method suitable for wireless ad hoc networks. In a time-synchronized TDMA network, the cluster head node centrally allocates dedicated channels to all other connected nodes, ensuring low-latency, conflict-free transmission of time-sensitive services such as network control signaling and short messages. Simultaneously, all nodes in the network reserve shared channels using a distributed competition method, fully utilizing shared channel resources and improving network-wide data transmission capabilities.

[0005] The technical solution adopted in the present invention is:

[0006] A hybrid channel allocation method applicable to a wireless self-organizing network includes the following steps:

[0007] (1) After each wireless self-organizing node is powered on, it listens for one superframe period. If it does not hear any time synchronization signal, it will act as the network cluster head node and start the network establishment process. If it hears one or more time synchronization signals, it will execute step (2).

[0008] (2) The newly started node selects a node with the highest time synchronization signal level as the time synchronization reference node and initiates the network access request process. The cluster head node allocates a dedicated channel for the newly started node;

[0009] (3) During network operation, each node in the network independently maintains its own shared channel list. The shared channel list includes the public shared channels of all nodes in the network and the dedicated shared channels of the node itself. The dedicated shared channels are the dedicated channels of all other nodes outside the two-hop range of the node itself. When transmitting services, each node gives priority to directly using its own dedicated channel. When the amount of service data exceeds the capacity range, it competes for the use of shared channels through reservation.

[0010] Wherein, step (2) specifically includes the following steps:

[0011] (201) The newly started node parses all the time synchronization signals it intercepts, and obtains the node ID of the node that sends the time synchronization signal, the time synchronization level, the total number of nodes on the network, the list of node IDs on the network, and the ID information of the cluster head node;

[0012] (202) The newly started node establishes a neighbor node list and selects the node with the largest received signal strength from the nodes with the highest time synchronization level as the time synchronization reference node to perform master-slave time synchronization;

[0013] (203) The newly started node selects an idle ID and initiates a network access request message on the service channel corresponding to the idle ID. The request content includes the identity information of the node, the time reference node ID and the reserved channel.

[0014] (204) After receiving the network access request message, the time reference node of the newly powered-on node forwards it to the upper-level time reference node hop by hop, and finally sends it to the network cluster head node;

[0015] (205) After receiving the network access request message, the network cluster head node parses the network access request message and authenticates the identity of the newly started node. After the authentication is passed, the network cluster head node checks whether the ID applied for by the newly started node has been occupied. If it has not been occupied, the original application ID is directly encapsulated in the network access success response message and returned to the newly started node. If it has been occupied, a reasonable dedicated channel is specified, and the specified dedicated channel number is encapsulated in the network access success response message and returned to the newly started node.

[0016] (206) After receiving the network access success response message, the newly started node parses the ID assigned by the network cluster head node, uses the service channel corresponding to the assigned ID as the dedicated channel of the node, and sends a network access success confirmation message to the cluster head node on the dedicated channel of the node; at the same time, it updates the local stored total number of network nodes and the list of node IDs on the network, and broadcasts the updated time synchronization signal on the synchronization channel corresponding to the node ID;

[0017] (207) After receiving the network access success confirmation message sent by the newly powered-on node, other nodes in the network update the locally stored total number of network nodes and the list of node IDs on the network, and broadcast the updated time synchronization signal on the synchronization channel corresponding to their respective node IDs.

[0018] Wherein, step (3) specifically includes the following steps:

[0019] (301) Each node in the network updates the public shared channel list based on the total number of nodes in the network, and obtains the list of two-hop neighbor nodes of each node by parsing the time synchronization signals of all one-hop neighbor nodes, and uses the dedicated channels of all other nodes outside the two-hop range as the dedicated shared channels of each node. Each node locally maintains the shared channel list, including the public shared channel and the dedicated shared channel;

[0020] (302) The node initiating shared channel reservation checks the reservation status of each channel in the locally maintained shared channel list, selects an idle shared channel from it, and initiates a reservation request in the dedicated channel of the node;

[0021] (303) After receiving the reservation request, the one-hop neighbor node of the node initiating the shared channel reservation resolves the reserved shared channel number and checks the shared channel list maintained by the node itself: if the reserved shared channel number does not exist in the list, no processing is performed; if the reserved shared channel number exists in the list and is in an occupied state, a reservation failure response is returned; if the reserved shared channel number exists in the list and is in an idle state, a reservation success response is returned;

[0022] (304) After one TDMA frame, if the node initiating the shared channel reservation does not receive a reservation failure response from the one-hop neighbor node, it sends a reservation success confirmation message on the corresponding dedicated channel, updates the local shared channel list, and starts to occupy the successfully reserved shared channel for service data transmission. After receiving the reservation success confirmation message, the one-hop neighbor node updates the local shared channel list; if the node initiating the shared channel reservation receives a reservation failure response from the one-hop neighbor node, it updates the local shared channel list and continues to initiate reservation requests for other idle shared channels;

[0023] (305) After completing data transmission, the node that successfully reserved the shared channel sends a reservation cancellation message on the corresponding dedicated channel and updates the local shared channel list. After receiving the reservation cancellation message, the one-hop neighbor node updates the local shared channel list.

[0024] Compared with the background technology, the present invention has the following main advantages:

[0025] The present invention designs a hybrid channel allocation method suitable for wireless self-organizing networks. First, the network cluster head node centrally allocates dedicated channels to newly connected nodes, ensuring the reliable transmission of time-sensitive services of each node. At the same time, considering that the dedicated channel of each node can be spatially reused by nodes beyond two hops, a mechanism for locally maintaining a shared channel list is designed. A mechanism for competing for shared channels through reservations on dedicated channels is also proposed. This method can avoid collisions caused by reservation message conflicts and reduce the number of information exchanges in competing for shared channels, ultimately meeting the high-capacity data transmission needs of each node. The hybrid channel allocation method fully utilizes all channel resources of the network, is simple and easy to implement, and can effectively improve the transmission capacity of the entire network. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The network establishment / network access process of a newly started node in an embodiment of the present invention.

[0027] Figure 2 The embodiment of the present invention is a process for reserving a shared channel among network nodes.

[0028] Figure 3 Schematic diagram of wireless ad hoc network frame structure.

[0029] Figure 4 Schematic diagram of the time slot structure of the frame synchronization channel in a wireless ad hoc network.

[0030] Figure 5 Schematic diagram of wireless ad hoc network topology.

[0031] Figure 6 Schematic diagram of the wireless ad hoc network frame service channel time slot structure (network access request).

[0032] Figure 7 Schematic diagram of the wireless self-organizing network frame service channel time slot structure (network access response).

[0033] Figure 8 Schematic diagram of the wireless self-organizing network frame service channel time slot structure (network access confirmation).

[0034] Figure 9 Schematic diagram of the time slot structure of the wireless ad hoc network frame service channel (reservation request).

[0035] Figure 10 Schematic diagram of the wireless ad hoc network frame service channel time slot structure (reservation response).

[0036] Figure 11 Schematic diagram of the time slot structure of the wireless ad hoc network frame service channel (reservation confirmation).

[0037] Figure 12 Schematic diagram of the time slot structure of wireless ad hoc network frame sharing channel.

[0038] Figure 13 Schematic diagram of the wireless ad hoc network frame service channel time slot structure (reservation cancellation). DETAILED DESCRIPTION

[0039] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings. The described embodiments are only specific examples of the present invention, not all examples.

[0040] like Figure 3 Figure 2 shows a schematic diagram of the frame structure of a wireless self-organizing network based on the TDMA mechanism. Each superframe is 2560ms long and consists of 32 TDMA frames. Each TDMA frame is 80ms long and consists of 80 time slots, each of which is 1ms long. The first two time slots of each TDMA frame serve as synchronization channels, including the broadcast time mark subframe (SYN_BC) and the synchronization response subframe (SYN_ACK), which are mainly used for time synchronization and information transmission between network nodes. The remaining 78 time slots are service channels. The network capacity is up to 64 nodes.

[0041] The process of establishing network / joining network for new startup nodes is as follows Figure 1 shown.

[0042] 1. Network cluster head node construction process

[0043] Step 1: The network cluster head node sets the time synchronization level to the highest level 0, the node ID to 1, and uses the first service channel TS1 as its own dedicated channel; at the same time, it uses its own clock directly as the timestamp information and broadcasts the time synchronization signal on the first synchronization channel of the first TDMA frame, as shown in the following example: Figure 4 As shown: fill in ID=1 in "Current Node ID"; fill in time synchronization level 0 in "Level"; fill in all 0s in "Time Base Node ID", indicating that this node itself is the node with the highest time synchronization level in the entire network; fill in the current clock information of this node in "Timestamp"; fill in 1 in "Total Number of Network Nodes"; fill in this node ID in "Network Node ID List"; fill in ID=1 in "Cluster Head Node ID"; SYN_ACK is used for time synchronization under the master-slave synchronization mechanism.

[0044] 2. The process of allocating dedicated channels from the network head node to the new node

[0045] by Figure 5 For example, node X is the network cluster head node, node H is a newly started node, and its neighboring nodes within one hop range are nodes B, C, G, and I.

[0046] Step 2: Node H parses the time synchronization signals sent by all one-hop neighbor nodes, obtains the ID and time synchronization level of each one-hop neighbor node, and obtains information such as the total number of nodes on the network, the list of node IDs on the network, and the cluster head node ID.

[0047] Step 3: Node H creates a one-hop neighbor node list {B, C, G, I} and selects node B with the largest received signal strength from the node set {B, C} with the highest time synchronization level as the time synchronization reference node, and performs master-slave time synchronization.

[0048] Step 4: Node H selects an idle ID=10 and initiates a network access request message on the service channel TS10 corresponding to ID=10. The network access request is as follows: Figure 6 As shown: fill in the network access request message in "Type", fill in the identity information of node H for authentication in "New node identity information", fill in TS10 in "Reservation channel", and fill in ID=5 in "Superior reference node ID".

[0049] Step 5: After receiving the network access request message, the time synchronization reference node B of node H parses the network access request content information and sends the information to the time reference node A of node B in the dedicated channel of node B. The information is forwarded hop by hop and finally sent to the network cluster head node X.

[0050] Step 6: After receiving the network access request message from node H, the network cluster head node X parses the information carried in the network access request and authenticates the identity of node H. After the authentication is passed, it checks the ID of the node in the network to confirm whether TS10 applied by node H has been occupied. If it has not been occupied, it will directly encapsulate ID=10 in the network access success response message and return it to node H. If it has been occupied, it will first specify a reasonable ID and then encapsulate the specified ID in the network access success response message and return it to node H. Figure 7 As shown: fill in the network access response message in "Type", fill in the node H ID = 10 in "Original application ID information", fill in TS10 in "Allocated channel", and fill in the node A ID = 2 in "Subordinate reference node ID".

[0051] Step 7: After receiving the network access success response message, node H parses out the ID assigned to it by the network cluster head node = 10, allocates channel TS10 as the dedicated channel of this node, and sends a network access success confirmation message to the cluster head node X on the dedicated channel TS10; the network access confirmation is as follows: Figure 8 As shown: fill in the network confirmation message in "Type", fill in TS10 occupied by node H in "Reservation Channel", and fill in node B's ID = 5 in "Superior Reference Node ID".

[0052] At the same time, node H updates the locally stored information such as the total number of network nodes and the list of node IDs on the network, and locally calculates the synchronization channel corresponding to ID = 10, obtains the second synchronization channel of the 5th TDMA frame, and broadcasts the updated time synchronization signal on the synchronization channel; Figure 4 As shown: fill in ID = 10 in "Current Node ID"; fill in time synchronization level 3 in "Level"; fill in ID = 5 in "Time Base Node ID"; fill in the current clock information of this node in "Timestamp"; fill in 10 in "Total Number of Network Nodes"; fill in the ID of all nodes in the network in "Online Node ID List" and mark the one-hop neighbor node; fill in ID = 1 in "Cluster Head Node ID"; SYN_ACK is used for time synchronization under the master-slave synchronization mechanism.

[0053] Step 8: After receiving the network access success confirmation message sent by node H, other nodes in the network update the locally stored information such as the total number of network nodes and the list of online node IDs, and broadcast the updated time synchronization signal on the synchronization channel corresponding to their respective node IDs.

[0054] 3. The process of competing for shared channels at network nodes, such as Figure 2 shown.

[0055] Step 9: Each node in the network updates its public shared channel list based on the total number of nodes in the network. It also obtains its own two-hop neighbor node list by parsing the time synchronization signals of all one-hop neighbor nodes. It uses the dedicated channels of all other nodes outside the two-hop range as its own dedicated shared channel. Each node locally maintains a shared channel list, including public shared channels and dedicated shared channels.

[0056] For example, after node H successfully joins the network, the total number of network nodes is 10, and the set of network nodes is {X, A, B, C, D, E, F, G, H, I}. Each node has 68 public shared channels, namely the set {TS11, TS12, ..., TS78}. Taking node H as an example, the set of nodes outside its two-hop range is {X, D, E, F}, and the set of dedicated shared channels for node H is {TS1, TS3, TS4, TS7}. Similarly, the set of nodes outside node F's two-hop range is {X, A, B, C, G, H, I}, and its set of dedicated shared channels is {TS1, TS2, TS5, TS6, TS8, TS9, TS10}. Each node locally maintains the following shared channel list, where a reservation status of 0 indicates that the current channel is the node's shared channel and is idle; a reservation status of 1 indicates that the current channel is the node's shared channel but is occupied.

[0057] Channel number (8 bits) Reservation status (1 bit) Occupied node ID (6 bits) 00000001 0 / 1 00000010 …… 01001110

[0058] Step 10: The node initiating shared channel reservation checks the reservation status of each channel in the locally maintained shared channel list, selects an idle shared channel from it, and initiates a reservation request in the dedicated channel of this node. Figure 9 As shown: fill in the shared channel reservation request message in "Type" and fill in the available shared channel number reserved for occupation in "Reservation Channel Number".

[0059] Step 11: After receiving the reservation request, the one-hop neighbor node of the node initiating the shared channel reservation resolves the reserved shared channel number and checks the shared channel list maintained by the node itself: if the reserved shared channel number does not exist in the table, no processing is done; if the reserved shared channel number exists in the table but is already occupied, a reservation failure response is returned; if the reserved shared channel number exists in the table and is idle, a reservation success response is returned. Figure 10 As shown: fill in the shared channel reservation response message in "Type", fill in the node ID that initiated the reservation of the shared channel in "Reservation Node ID", and fill in the shared channel number occupied by the reservation in "Reservation Channel Number"; fill in 1 in "Flag" when the reservation is successful, and fill in 0 in "Flag" when the reservation fails.

[0060] Step 12: After one TDMA frame, if the node initiating the shared channel reservation does not receive a reservation failure response from its one-hop neighbor node, it sends a reservation success confirmation message on its dedicated channel to update the local shared channel list. Figure 11 As shown: Fill in the shared channel reservation confirmation message in "Type" and fill in the shared channel number that has been successfully reserved in "Reservation Channel Number".

[0061] At the same time, the node that initiates the shared channel reservation begins to occupy the shared channel that has been successfully reserved for business data transmission; its one-hop neighbor node updates the local shared channel list after receiving the reservation success confirmation message. Figure 12 shown.

[0062] If the node initiating the shared channel reservation receives a reservation failure response from its one-hop neighbor node, it also updates the local shared channel list and can continue to initiate reservation requests for other idle shared channels.

[0063] Step 13: After completing data transmission, the node that successfully reserved the shared channel needs to send a reservation cancellation message on its dedicated channel and update the local shared channel list. Figure 13 As shown in the following example: Enter the shared channel reservation cancellation message in "Type" and the shared channel number to be canceled in "Cancel reservation channel number". After receiving the reservation cancellation message, the neighboring node will also update the local shared channel list.

Claims

1. A hybrid channel allocation method suitable for wireless ad hoc networks, characterized in that: The process includes the following: (1) After each wireless self-organizing node is powered on, it listens for one superframe period. If it does not hear any time synchronization signal, it will act as the network cluster head node and start the network construction process. If one or more time synchronization signals are detected, then step (2) is executed; (2) The newly started node selects a node with the highest time synchronization signal level as the time synchronization reference node and initiates the network access request process. The cluster head node allocates a dedicated channel for the newly started node; (3) During network operation, each node in the network independently maintains its own shared channel list, which includes the public shared channels of all nodes in the network and the dedicated shared channels of the node itself. The dedicated shared channels are the dedicated channels of all other nodes outside the two-hop range of the node itself. When transmitting services, each node gives priority to directly using its own dedicated channel. When the amount of service data exceeds the capacity range, it competes for the use of shared channels through reservation. Wherein, step (2) specifically includes the following steps: (201) The newly started node parses all the time synchronization signals it hears and obtains the node ID that sends the time synchronization signal, the time synchronization level, the total number of nodes on the network, the list of node IDs on the network, and the cluster head node ID information; (202) The newly started node establishes a neighbor node list and selects the node with the largest received signal strength from the nodes with the highest time synchronization level as the time synchronization reference node to perform master-slave time synchronization; (203) The newly started node selects an idle ID and initiates a network access request message on the service channel corresponding to the idle ID. The request content includes the identity information of the node, the time reference node ID and the reservation channel. (204) After receiving the network access request message, the time reference node of the newly powered-on node forwards it to the upper-level time reference node hop by hop, and finally sends it to the network cluster head node; (205) After receiving the network access request message, the network cluster head node parses the network access request message and authenticates the identity of the newly started node. After the authentication is passed, it checks whether the ID applied for by the newly started node has been occupied. If it has not been occupied, the original application ID is directly encapsulated in the network access success response message and returned to the newly started node. If it has been occupied, a reasonable dedicated channel is specified, and the specified dedicated channel number is encapsulated in the network access success response message and returned to the newly started node. (206) After receiving the network access success response message, the newly started node parses the ID assigned by the network cluster head node, uses the service channel corresponding to the assigned ID as the dedicated channel of the node, and sends a network access success confirmation message to the cluster head node on the dedicated channel of the node; at the same time, it updates the local stored total number of network nodes and the list of node IDs on the network, and broadcasts the updated time synchronization signal on the synchronization channel corresponding to the node ID; (207) After receiving the network access success confirmation message sent by the newly powered-on node, other nodes in the network update the local stored total number of network nodes and the list of node IDs on the network, and broadcast the updated time synchronization signal on the synchronization channel corresponding to their respective node IDs.

2. The hybrid channel allocation method for wireless ad hoc networks according to claim 1, characterized in that: Step (3) specifically includes the following steps: (301) Each node in the network updates the public shared channel list based on the total number of nodes in the network, and obtains the list of two-hop neighbor nodes of each node by parsing the time synchronization signals of all one-hop neighbor nodes. The dedicated channels of all other nodes outside the two-hop range are used as the dedicated shared channels of each node. Each node locally maintains the shared channel list, including public shared channels and dedicated shared channels. (302) The node initiating shared channel reservation checks the reservation status of each channel in the locally maintained shared channel list, selects an idle shared channel from it, and initiates a reservation request in the dedicated channel of the node; (303) After receiving the reservation request, the one-hop neighbor node of the node initiating the shared channel reservation resolves the reserved shared channel number and checks the shared channel list maintained by the node itself: if the reserved shared channel number does not exist in the list, no processing is performed; if the reserved shared channel number exists in the list and is in an occupied state, a reservation failure response is returned; if the reserved shared channel number exists in the list and is in an idle state, a reservation success response is returned; (304) After one TDMA frame, if the node initiating the shared channel reservation does not receive a reservation failure response from the one-hop neighbor node, it sends a reservation success confirmation message on the corresponding dedicated channel, updates the local shared channel list, and starts to occupy the shared channel with successful reservation for service data transmission. After receiving the reservation success confirmation message, the one-hop neighbor node updates the local shared channel list; if the node initiating the shared channel reservation receives a reservation failure response sent by the one-hop neighbor node, it updates the local shared channel list and continues to initiate reservation requests for other idle shared channels; (305) After completing data transmission, the node that successfully reserved the shared channel sends a reservation cancellation message on the corresponding dedicated channel and updates the local shared channel list. After receiving the reservation cancellation message, the one-hop neighbor node updates the local shared channel list.

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