Terahertz wireless network directional access control method with high efficiency and high bandwidth utilization rate

Abstract

This invention claims protection for a high-efficiency, high-bandwidth-utilization directional access control method for terahertz wireless networks, comprising: designing a memory-assisted control interaction mechanism; designing a priority-based channel reservation mechanism; each node in the network maintains a location information storage table to store location information that the node has broadcast in the network, and the node's location information can be quickly obtained by looking up the table. During the control interaction process, whether or not the location information field in the control frame is omitted is determined by whether the location information has changed, thereby reducing the control interaction time and increasing the time for data transmission on the THz channel. By setting priorities for nodes, the success rate of nodes that can transmit data in parallel to compete for the channel is increased, the channel is reserved in advance, and the utilization rate of the THz channel is improved.

Description

Technical Field

[0001] This invention belongs to the field of terahertz technology, specifically to a terahertz wireless network directional access control method. Background Technology

[0002] One alternative to fifth-generation (5G) mobile communication systems is millimeter-wave (mmWave) communication, which offers a wide bandwidth ranging from hundreds of MHz to several GHz. With such available bandwidth, mmWave systems can provide significantly more bandwidth than traditional microwave communication systems below 5 GHz. While data rates in the mmWave band can reach several Gbps, this is still insufficient to meet the ever-increasing data traffic demands of future wireless communications. For example, future wireless local area network (WLAN) and wireless personal area network (WPAN) systems require data rates of at least 10 Gbps. Furthermore, the minimum data rate for virtual reality (VR) devices is expected to reach 10 Gbps. In addition, uncompressed ultra-high-definition video and 3D video will reach data rates of 24 Gbps and 100 Gbps, respectively. Therefore, research into higher frequency resources is urgently needed.

[0003] Terahertz electromagnetic radiation (ranging from 0.1 THz to 10 THz), situated between optical and radio frequencies, has a bandwidth of 0.03 mm to 3 mm, located at the boundary between microwaves and near-infrared light waves. Currently, terahertz communication technology is still in the research and development stage, but many research institutions and companies have begun to invest significant resources and effort in its research and development. It is expected that in the next few years, terahertz communication technology will become an important branch of human information and communication.

[0004] However, the propagation range of terahertz waves is significantly limited by high propagation losses in air and adsorption losses from water vapor and oxygen. Therefore, high-gain antennas are urgently needed to effectively compensate for this. Large-scale phased array antennas are suitable for terahertz communication systems. Based on the principle of beam interference, phased array technology adjusts the phase and amplitude of each antenna element, concentrating electromagnetic energy in a predetermined direction. By using an array antenna, high-gain and highly directional beams can be effectively obtained, improving the communication range. Due to the unique characteristics of terahertz waves, existing Media Access Control (MAC) protocols in traditional networks cannot be directly applied because they do not consider the unique characteristics of the terahertz band, such as path and molecular losses, multipath propagation, reflection, and scattering. Therefore, a new, efficient MAC protocol that considers the characteristics of the terahertz frequency band and antenna requirements is needed. While the characteristics of terahertz waves limit their communication distance, using terahertz directional antennas can enhance this distance, but this requires high synchronization of the terahertz transceiver equipment. By decoupling the control plane and data plane, the low-frequency band is used to exchange control information, providing an information foundation for directional antenna alignment in the high-frequency band, thereby enabling high-speed data transmission. This scheme requires providing each node with a location-enabled device or installing a device to assist in the location of ordinary nodes. Although this scheme has lower overhead and easier beamforming, the equipment cost is relatively higher.

[0005] The closest prior art to this invention comes from: Zhou Haidong. Research on dual-channel MAC protocol of terahertz wireless personal area network [D]. Chongqing University of Posts and Telecommunications, 2018.

[0006] The specific details of the technical solution in the existing technology are as follows:

[0007] The existing terahertz dual-channel MAC protocols have the following problems: (1) redundancy in control overhead when the source node and the destination node exchange control information; (2) when the source node and the destination node transmit data on the THz channel, in order to prevent other nodes from affecting the data transmission process between the source node and the destination node, other nodes cannot exchange control information, resulting in the WIFI channel being idle and causing low spatial multiplexing rate. To address the above problems, this paper designs a parallel transmission terahertz wireless personal area network dual-channel MAC protocol—PTDC-MAC protocol. The PTDC-MAC protocol improves network throughput and reduces data transmission latency by using an adaptive cancellation mechanism for transmitting and receiving RN location information and a multi-pair node parallel transmission mechanism.

[0008] 1. Adaptive cancellation of RN location information transmission and reception mechanism

[0009] In the "adaptive cancellation of RN location information transmission and reception" mechanism, when the source node performs RTS / CTS frame interaction, each RN stores "whether the other RN knows its own location" and "the other RN knows its own location" in the location information acquisition table. If it needs to communicate with the other RN again in the future, and the other RN already knows its own location information and its own location has not changed, then the location information can be omitted when interacting with the other RN in RTS / CTS, thereby reducing redundant control overhead in RTS / CTS.

[0010] 2. Multi-node parallel transmission mechanism

[0011] The basic idea of ​​this new mechanism is as follows: Node A sends an RTS frame to Node B on the WiFi channel. After receiving the RTS frame, nodes other than Node B will remain silent for a period of time (the silence time is RTT / 2) and, based on the location information in the RTS frame, shield the beam direction that is aligned with the directional antenna of Node A on the terahertz channel. The shielding time is the sum of the time required for Node A to send data on the terahertz channel and the test delay (which can be obtained from the "duration" value in the RTS frame). Subsequently, node A transmits data to node B on the THz channel. During this data transmission period, if node C needs to send data to node D, node C sends an RTS frame to node D. After receiving the RTS frame, node D obtains the beam direction aligned with node C's directional antenna based on the position information in the RTS frame. Then, it determines whether this beam direction is blocked. If it is, node D replies to node C with a No Clear To Send (NCTS) frame. Node C remains silent for a period of time based on the Duration field value in the NCTS frame (the silence time is the beam direction blocking time). If not, node D replies to node C with a CTS frame. In this way, nodes C and D can adjust their directional antennas and align with each other based on the exchanged messages, and finally transmit data on the THz channel.

[0012] The second prior art closest to this invention

[0013] The closest prior art to this invention is from: Zhao Zijun. Research on dual-channel MAC protocol for terahertz wireless networks [D]. Chongqing University of Posts and Telecommunications, 2020.

[0014] The specific details of the technical solution of Existing Technology 2 are as follows:

[0015] 1. Low space separation reuse rate

[0016] In the TAB-MAC protocol, to address the potential message collisions between nodes, CSMA / CA access channels are employed. Through the exchange of RTS / CTS frames, message collisions are prevented by reserving channel time, and the location information of both nodes is exchanged. However, it is precisely because of this channel time reservation mechanism that the TAB-MAC protocol cannot achieve parallel transmission, thus failing to fully utilize the high data transmission rate of THz.

[0017] 2. Low channel resource utilization

[0018] Due to the channel reservation time mechanism, only one pair of nodes is allowed to communicate during the reserved channel time, while other nodes must remain silent. The TAB-MAC protocol's channel reservation time includes the time occupied by the Wi-Fi channel and the time occupied by the THz channel. Therefore, when a node is transmitting data on the THz channel, the Wi-Fi channel is idle, resulting in a waste of channel resources. Summary of the Invention

[0019] This invention aims to solve the problems of the prior art mentioned above. It proposes a highly efficient and high-bandwidth-utilization directional access control method for terahertz wireless networks. The technical solution of this invention is as follows:

[0020] A highly efficient and bandwidth-utilization-efficient terahertz wireless network directional access control method includes the following steps:

[0021] The design of a memory-assisted control interaction method is as follows: For nodes that are performing control information interaction for the first time in the network or retransmitting a control frame after the first failed transmission, the control information interaction process in the TAB-MAC protocol is followed; for nodes that have successfully communicated, if the node needs to transmit or receive data at a certain moment and its own node location information has not changed, the location information field in the control frame is removed; for nodes that have successfully communicated, if the location information of both the source and destination nodes has changed, the updated location information is broadcast omnidirectionally to all nodes in the network through the Sub-6G frequency band. After receiving the new location information of the node, the other nodes update the location information entries in their own location information storage table and perform the control interaction process according to the original protocol.

[0022] Design a priority-based channel reservation method: After a node in the network successfully reserves a channel, the other nodes can start the next round of channel reservation. That is, all nodes except those in communication can reserve channels. If the node reserving the channel does not affect the data transmission of the node in communication, then the node is set as a high-priority node, while the other nodes that affect the node in communication are set as low-priority nodes and reserve channels normally.

[0023] Furthermore, the specific operation steps of the memory-assisted control interaction method are as follows:

[0024] Step A1: Each node in the network maintains its own location information storage table, which records the location information and MAC address information of all nodes in the network except itself. When the location information storage table of all nodes is initialized, all entries are set to NULL.

[0025] Step A2: When the source RN needs to send data, the source RN determines whether this node is sending an RTS frame for the first time or retransmitting an RTS frame for the first time. If yes, proceed to step A3; otherwise, proceed to step A4.

[0026] Step A3: The source RN sends an RTS frame with location information, and then proceeds to step A5;

[0027] Step A4: The source RN determines whether the location information of this node has changed. If it has changed, it sends an RTS frame with the new location information; if it has not changed, it sends an RTS frame with the location information omitted.

[0028] Step A5: After receiving the RTS frame, the destination RN extracts the information carried in the RTS frame. If there is no location information in the RTS frame, it means that the location information of the source RN has not changed, and the destination RN directly uses the location information of the source RN stored in its local location information storage table; otherwise, it uses the location information carried in the RTS frame.

[0029] Step A6: The destination RN determines whether this node is responding to a CTS frame for the first time or retransmitting a CTS frame for the first time. If so, it responds with a CTS frame containing the destination RN's location information; otherwise, it responds with a CTS frame without location information.

[0030] Step A7: After the source RN and destination RN successfully exchange control information, both the source and destination RNs have obtained the location and antenna information of the other node. The source and destination RNs switch to the THz channel and beamform to align their THz directional antennas. The source RN transmits a TTS frame directionally on the THz channel, and the destination RN, upon receiving it, replies with an ACK frame directionally. Subsequently, the source RN uses its directional antenna to transmit data to the destination RN on the THz channel. After receiving the data frame and confirming its correctness, the destination RN replies with an ACK frame to the source RN.

[0031] Furthermore, the location information storage table is used to record all nodes in the network that have broadcast their location information and MAC address information omnidirectionally in the low-frequency band. The location information storage table has three entries: sequence number, node location information, and node MAC address information. The sequence number records the order in which all nodes in the network first broadcast control information via control frames. When a node sends an RTS control frame omnidirectionally in the Sub-6G band, the destination node will also reply with a CTS control frame. Therefore, each node can add the location information and MAC address information of the source node and the destination node to the location information storage table maintained by this node.

[0032] Furthermore, the specific operation steps of the priority-based channel reservation method are as follows:

[0033] Step B1: The node determines whether it has data to send. If not, it does nothing; if so, it proceeds to step B2.

[0034] Step B2: The source RN determines whether the destination RN is a node that is currently communicating in the network. If so, it sets the current node as a high-priority node and sets the initial value of retry_count. If not, it sets the current node as a low-priority node and sets the initial value of retry_count.

[0035] Step B3: The node listens to see if the channel is idle. If the channel is busy, it continues to listen; if the channel is idle, it proceeds to step B4.

[0036] Step B4: After waiting for the DIFS duration, the source RN sends an RTS frame omnidirectionally on the 5G channel and determines whether the source RN has received the CTS frame sent by the destination RN. If no CTS frame is received, proceed to step B5; if a CTS frame is received, proceed to step B6.

[0037] Step B5: Set the retry_count values ​​for high-priority nodes and low-priority nodes. If the retry_count value of the low-priority node is greater than the maximum backoff count or the retry_count value of the high-priority node is equal to the maximum backoff count, end the current channel reservation process; otherwise, recalculate the backoff duration, listen to the channel again, and wait for the channel to become available.

[0038] Step B6: The source RN determines the priority setting type of this node. If it is a high-priority node, proceed to step B7; if the node is a low-priority node, wait for the destination RN to finish transmitting or receiving data before proceeding to step B7.

[0039] Step B7: The source RN and the destination RN align their antennas using beamforming, and then transmit a TTS test frame directionally on the THz channel. If the source RN does not receive an ACK frame from the destination RN, the current channel reservation process ends; if it receives an ACK frame from the destination RN, the source RN sends a data frame to the destination RN, and the destination RN replies with an ACK frame after receiving the data frame.

[0040] Step B8: After the source RN and the destination RN have finished communicating, the high-priority node resets the retry_count value to 0 according to the original BEB algorithm; the low-priority node randomly selects a value in the range [0, retry_count] as the initial value for the node to initialize retry_count in the next round.

[0041] Furthermore, in the priority-based channel reservation method described above: in order to give nodes capable of parallel transmission a greater probability of successfully competing for the channel, nodes capable of parallel transmission are set as high-priority nodes, while nodes that cannot perform parallel transmission and can only communicate after waiting for the currently communicating node to finish transmitting or receiving data are set as low-priority nodes; the core of setting priority nodes is the value of bit b4 in the frame control field. When the value of bit b4 is 0, it indicates that the node sending the frame is a low-priority node, and vice versa when it is 1, it is a high-priority node.

[0042] The advantages and beneficial effects of this invention are as follows:

[0043] (1) Each node in the network of the present invention maintains a location information storage table to store the location information that the node has broadcast in the network. The node location information can be quickly obtained by looking up the table.

[0044] (2) During the control interaction process, the location information field in the control frame is omitted based on whether the location information is changed, thereby reducing the control interaction time and increasing the data transmission time on the THz channel.

[0045] (3) By setting priorities for nodes, the success rate of data nodes competing for channels in parallel can be increased, channels can be reserved in advance, and the utilization rate of THz channels can be improved. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of a preferred embodiment of the Terahertz Wireless Personal Area Network (THz-WPAN) structure provided by the present invention;

[0047] Figure 2 This is a schematic diagram of a THz-WLAN;

[0048] Figure 3It is a TAB-MAC protocol network model;

[0049] Figure 4 This is a diagram of the TAB-MAC protocol RTS / CTS frame structure;

[0050] Figure 5 This is a diagram of the RTS / CTS frame structure with location information omitted.

[0051] Figure 6 This is the operation flowchart of the source RN;

[0052] Figure 7 This is the flowchart of the RN operation.

[0053] Figure 8 Flowchart of the control and interaction mechanism for memory assistance;

[0054] Figure 9 This is a flowchart illustrating the operation of a priority-based channel reservation mechanism. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and thoroughly described below with reference to the accompanying drawings. The described embodiments are merely some embodiments of the present invention.

[0056] The technical solution of the present invention to solve the above-mentioned technical problems is:

[0057] The abbreviations and key terms involved in this invention are:

[0058] Abbreviations and key terms

[0059]

[0060]

[0061] Terahertz Wireless Personal Area Network Basic Architecture

[0062] A schematic diagram of a Terahertz Wireless Personal Area Network (THz-WPAN) is shown below. Figure 1 As shown, the network consists of multiple DEVs (Device) and a PicoNet Coordinator (PNC).

[0063] THz-WPAN is a wireless communication network that uses the terahertz frequency band as the communication carrier and has a communication range of less than 10 meters. Building upon the rich service types and final link connection between wireless networks and mobile smart terminals provided by existing wireless personal area networks (WPANs), terahertz WPANs offer greater bandwidth and higher transmission rates, effectively alleviating the problem of limited wireless spectrum resources. Terahertz WPANs are classified as high-speed WPANs, providing surrounding smart mobile terminals with the ability to access wireless networks for high-speed data communication.

[0064] Terahertz Wireless LAN Basic Architecture

[0065] THz-WLAN uses the terahertz frequency band as its carrier, supporting data transmission rates up to 10Gbps and various types of network applications and services. THz-WLAN is primarily used for high-speed data transmission and communication between low-power devices, such as robots, sensors, medical equipment, and smart home devices. Furthermore, THz-WLAN can also be applied to indoor positioning, the Internet of Things (IoT), and other fields. Figure 2 The diagram illustrates a THz-WLAN network architecture model. This model consists of multiple Regular Nodes (RNs) and a central Control Node (CN), which acts as the access point and serves as the control center for the entire network. In THz-WLAN, communication between nodes includes point-to-point and multicast communication. In point-to-point communication, two nodes can directly establish a connection and communicate, with one node acting as the sender and the other as the receiver. Each node has its own address, allowing other nodes to directly broadcast their addresses to each other and perform beamforming based on the broadcast address information for terahertz antenna alignment. Multicast communication refers to a node simultaneously sending data packets to multiple nodes. In THz-WLAN, multicast communication can be implemented through the CN. The sender sends data packets to the CN, which then copies and forwards the packets to multiple receivers. Multicast communication can effectively improve network transmission efficiency, especially in scenarios where the same data needs to be broadcast to multiple nodes.

[0066] TAB-MAC protocol

[0067] like Figure 3The diagram shows a network model for the TAB-MAC protocol, which consists of regular nodes and anchor nodes (ANs). Both anchor nodes and regular nodes can exchange control information in the Sub-6 GHz band via omnidirectional antennas. Anchor nodes can identify their location and periodically broadcast beacon signals by being equipped with GPS modules or manually configured, while regular nodes determine their location by receiving beacon signals. Furthermore, regular nodes are equipped with beamforming antenna arrays for terahertz communication.

[0068] In terahertz communication networks, to address the "orientation" problem, nodes can estimate their own position and communicate with specific transmitters or receivers using the Sub-6 GHz band. This protocol chooses the Sub-6 GHz band for control information exchange because of its advantages in transmission distance and omnidirectionality. Conventional nodes require three non-collinear anchor nodes for location assistance in two-dimensional space, and at least four non-coplanar anchor nodes for location assistance in three-dimensional space. When establishing a terahertz link, the terahertz beamforming antenna arrays of the transmitter and receiver need to be correctly aligned, which can be achieved by the nodes estimating their own positions. Due to the severe path loss and limited transmission power of terahertz systems, very high directional gain or very narrow beamwidth is required. These parameters depend on the transmission frequency and the distance between the transmitter and receiver, and can be calculated from the node's position. The communication process of this protocol is divided into two phases, and the specific operational steps are as follows:

[0069] 1. Node discovery and coupling phase

[0070] This protocol design leverages the advantages of omnidirectional 5G channel communication to discover and couple transmitters and receivers, then aligns their terahertz beamforming antennas. First, the transmitter sends an extended RTS (Request-To-Send, RTS-NI) frame containing node location information. When the receiver becomes available, it replies with an extended CTS (Clear-To-Send, CTS-NI) frame containing its node information. Once both nodes have obtained each other's location and antenna information, they can calculate the straight-line distance and beamwidth between them, aligning themselves using their beamforming antennas.

[0071] In the TAB-MAC protocol, all RNs use CSMA / CA to access the channel. If an RN finds that its transmitted information collides with that of other RNs, it will perform a binary backoff operation according to formula (1) and wait for T. BF The message will be resent after a certain time. Where T... BF The calculation method is as follows:

[0072] T BF=[rand(n)×(2 CW -1)]×2τ (1)

[0073] In the formula, T BF τ is the binary exponential backoff time; rand(n) is a random number; CW is the backoff window; τ is the basic backoff time slot.

[0074] The value of CW is determined as CW = min{retry_count, 3}, where retry_count is the number of backoffs. When the number of backoffs is greater than 3 but less than the maximum number of backoffs, CW is set to 3. When the number of backoffs is greater than the maximum number of backoffs, the retransmission of the message is abandoned and a new channel is reserved.

[0075] 2. THz Channel Data Transmission Stage

[0076] After the above stages, the beamforming antennas of the transmitter and receiver are pointing towards each other, meaning the transmitter is ready to transmit data in the terahertz band. First, to check the channel conditions between the transmitter and receiver, the transmitter sends a TTS frame to ensure their directional antennas are pointing towards each other and that line-of-sight propagation between them is available. Once the transmitter receives an acknowledgment (ACK) frame from the receiver, it begins transmitting data.

[0077] To address the aforementioned issues, the HEPT-MAC protocol was proposed. The HEPT-MAC protocol employs a multi-pair node parallel transmission mechanism.

[0078] The main idea of ​​the multi-node parallel transmission mechanism is that when the source and destination nodes are exchanging control frames, their reserved channel time should be reallocated. Instead of occupying the total time of the WIFI channel and the THz channel, it should be reallocated to the time for control frame exchange. Once the reserved channel time expires, other nodes immediately begin a new round of channel contention, i.e., re-reserving the channel.

[0079] When two communicating nodes switch to the THz channel to prepare for data transmission, assuming the source node is S and the destination node is D, and that the source and destination nodes are currently communicating, while C, E, and F are other nodes, when other node C receives an RTS frame from the omnidirectional source node S, it extracts the site address information of the source and destination nodes from the RTS frame. If other node C requests to send data in the next moment, according to the half-duplex communication mode of the existing terahertz dual-channel MAC protocol nodes, node C should also determine whether the destination address is the site address of the currently communicating node. If the destination address of the data that node C wants to send in the next moment is the source node S or the destination node D, then it must wait for the currently communicating node to finish transmitting data; if the destination address of the data that node C wants to send is not the site address of the currently communicating node, then it will normally compete for the channel and reserve the channel. When other node E receives an RTS frame and a C-ACK frame from the omnidirectional source node S, it extracts the position coordinates of the source node from the RTS frame and the position coordinates of the destination node from the C-ACK frame. If node E requests to send data in the next moment, and the destination address is not the source node S or the destination node D, but node F, then when node F receives the RTS frame sent by node E, it extracts the location coordinates of node E and determines whether nodes E and F are collinear with nodes S and D. If they are collinear, beam overlap will occur, causing interference. Node F should remain silent until the data transmission is complete. If they are not collinear, it should immediately reply with a D-TTS frame to node E.

[0080] Basic premise of the present invention

[0081] The technical solutions contained in this invention involve the following presets:

[0082] (1) Data transmission between nodes in a terahertz wireless local area network is performed using directional antennas.

[0083] (2) Both the transmission and reception of control frames are omnidirectional;

[0084] (3) Some RNs in a terahertz wireless local area network can communicate directly with each other.

[0085] The technical problem to be solved by the present invention

[0086] In the context of terahertz wireless personal area networks, the main problem that this invention needs to solve is:

[0087] In existing protocols, before an idle node can transmit data with other nodes, it must exchange control information with the destination node to obtain the destination node's location and antenna information, providing basic information for subsequent high-speed data transmission in the THz range. Since the node's control information exchange process requires omnidirectional transmission of control frames in the low-frequency band, all nodes in the network can obtain the node's location and antenna information. If a node discovers that its location has not changed when sending a control frame, but still sends a control frame with location information according to the original protocol's control exchange process, this incurs additional control overhead. Maintaining a network table for each node, recording the location information broadcast by other nodes in the network during previous channel reservations, can reduce this control overhead.

[0088] In a network where all nodes can pre-reserve channels, assuming several pairs of nodes are currently communicating, when an idle node wants to initiate a handshake with other nodes, all nodes compete for the channel using CSMA / CA. While this method is relatively fair in the TAB-MAC protocol, two scenarios exist in this network: First, the idle node's successful channel acquisition does not affect the transmission of currently communicating nodes, allowing it to immediately transmit data in parallel with other communicating node pairs. Second, the idle node cannot immediately transmit data after successfully acquiring the channel, but must wait for currently communicating nodes to complete their data transmission or reception before transmitting data. Clearly, CSMA / CA is no longer suitable for this network. Therefore, improving the channel contention success rate of nodes capable of parallel transmission can be considered to increase network throughput.

[0089] The novel mechanism proposed in this invention

[0090] This invention proposes a dual-channel media access control method for terahertz wireless networks with high utilization and low overhead, which includes the following two innovative mechanisms:

[0091] (1) Memory-assisted control and interaction mechanism.

[0092] (2) Priority-based channel reservation mechanism.

[0093] The two new mechanisms are described in detail below.

[0094] Memory-assisted control interaction mechanism

[0095] The main considerations for memory-assisted control interaction mechanisms can be divided into three aspects.

[0096] 1. For nodes that are performing control information exchange in the network for the first time or retransmitting the control frame after the first failed transmission of the control frame, the control information exchange process in the TAB-MAC protocol shall be followed.

[0097] 2. For nodes that have already passed (the node can be the source node sending data or the destination node receiving data), if the node has data to transmit or receive at a certain moment and its own node position information has not changed, the position information field in the control frame can be removed to reduce control overhead.

[0098] 3. For nodes that have successfully communicated, if the location information of both the source and destination nodes has changed, the updated location information will be broadcast omnidirectionally to all nodes in the network via the Sub-6G frequency band. After receiving the new location information of the node, the other nodes will update the location information entries in their own location information storage table and perform the control interaction process according to the original protocol.

[0099] The main idea of ​​the new mechanism is to reduce the overall network control overhead by minimizing unnecessary location information overhead, thereby saving more time for nodes to transmit data on the THz channel. To store the location information of each node, each node maintains its own location information storage table. This table records the location information and MAC address information of all nodes that have already broadcast omnidirectionally in the low-frequency band. Table 1 shows the location information storage table maintained by each node, which contains three entries: sequence number, node location information, and node MAC address information. The sequence number records the order in which all nodes in the network first broadcast control information via control frames. When a node sends an RTS control frame omnidirectionally in the Sub-6GHz band, the destination node will also reply with a CTS control frame. Therefore, each node can add the location information and MAC address information of the source and destination nodes to its own location information storage table.

[0100] Table 1 Location Information Storage Table

[0101]

[0102] When the number of nodes in the network is too large and most nodes have already sent their own control frames in the Sub-6GHz low-frequency band, based on the idea of ​​a memory-assisted omission control interaction mechanism, if the node's position has not changed, then... Figure 4 The control frame structure in the TAB-MAC protocol is shown below; if the node's location changes, the location information field in the control frame needs to be removed, such as... Figure 5 The diagram shows the control frame structure with location information omitted.

[0103] The specific operational steps of this mechanism are as follows:

[0104] Step 1: Each node in the network maintains its own location information storage table, which records the location information and MAC address information of all nodes in the network except the node itself. When initializing the location information storage table, all entries of all nodes are set to NULL.

[0105] Step 2: When the source RN needs to send data, the source RN determines whether this node is sending an RTS frame for the first time or retransmitting an RTS frame for the first time. If yes, proceed to step 3; otherwise, proceed to step 4.

[0106] Step 3: The source RN sends an RTS frame with location information, and then proceeds to step 5.

[0107] Step 4: The source RN determines whether the location information of this node has changed. If it has changed, it sends an RTS frame with the new location information; if it has not changed, it sends an RTS frame with the location information omitted.

[0108] Step 5: After receiving the RTS frame, the destination RN extracts the information carried in the RTS frame. If there is no location information in the RTS frame, it means that the location information of the source RN has not changed, and the destination RN directly uses the location information of the source RN stored in its local location information storage table; otherwise, it uses the location information carried in the RTS frame.

[0109] Step 6: The destination RN determines whether this is the first time it replies to a CTS frame or the first time it retransmits a CTS frame. If so, it replies with a CTS frame containing the destination RN's location information; otherwise, it replies with a CTS frame without location information.

[0110] Step 7: After the source RN and destination RN successfully exchange control information, both the source and destination RNs have obtained the location and antenna information of the other node. The source and destination RNs switch to the THz channel and beamform to align their THz directional antennas. The source RN transmits a TTS frame directionally on the THz channel, and the destination RN, upon receiving it, replies with an ACK frame directionally. Subsequently, the source RN uses its directional antenna to transmit data to the destination RN on the THz channel. After receiving the data frame and confirming its correctness, the destination RN replies with an ACK frame to the source RN.

[0111] Priority-based channel reservation mechanism

[0112] The main idea of ​​this mechanism is as follows: after a node in the network successfully reserves a channel, the remaining nodes can begin the next round of channel reservation. That is, all nodes except those currently communicating can reserve a channel. If a node reserving a channel does not affect the data transmission of a node currently communicating, that node is set as a high-priority node, while other nodes that affect the currently communicating nodes are set as low-priority nodes and reserve channels normally. Compared with existing protocols, the new mechanism, while maximizing the probability of data nodes capable of parallel transmission successfully competing for a channel, does not affect the channel reservation of other ordinary nodes. Otherwise, nodes that could originally transmit in parallel might be stuck in a state of waiting for nodes that are currently transmitting or receiving data to finish because ordinary nodes have successfully reserved channels. Meanwhile, nodes capable of parallel transmission might remain in a waiting state due to failure to compete for a channel. If this node successfully hands over to another node, this could cause some nodes to be unable to transmit data to the destination node for a long time, affecting network throughput.

[0113] In the novel mechanism proposed in this invention, to increase the probability of nodes capable of parallel transmission successfully competing for the channel, these nodes are designated as high-priority nodes. Nodes that cannot perform parallel transmission and can only communicate after a currently communicating node has finished transmitting or receiving data are designated as low-priority nodes. The core of setting priority nodes is the value of bit b4 in the frame control field. When the value of bit b4 is 0, it indicates that the node sending the frame is a low-priority node; conversely, a value of 1 indicates a high-priority node. The types of each control frame are shown in Table 2.

[0114] Table 2 Control Frame Types

[0115]

[0116]

[0117] Compared to the traditional Binary Exponential Backoff (BEB) algorithm, this mechanism modifies the initialization method of the contention window value. Specifically, the backoff window value for high-priority nodes differs from that for low-priority nodes. This is because parallel transmission can be performed without affecting other nodes currently communicating. When the network data volume is large, the throughput and channel utilization of parallel transmission are better than queuing for data transmission. Therefore, when using the BEB algorithm for the first backoff, the backoff window of high-priority nodes remains unchanged to increase the probability of that node successfully acquiring the channel in the next contention window. In the original BEB algorithm, after a node successfully completes communication, the retry_count value is initialized to 0 when reserving the channel for the next time. In this mechanism, the retry_count value of high-priority nodes is initialized in the same way as the original BEB algorithm, while low-priority nodes randomly select a value between [0, retry_count] as the initial value of retry_count for the next round of channel contention. If the target node of the low-priority node in the next round of channel contention is not a node that is currently communicating, then the node is set as a high-priority node. This mechanism improves the channel utilization by increasing the success rate of high-priority nodes in contention for the channel.

[0118] The specific operation steps of the priority-based channel reservation mechanism proposed in this invention are as follows:

[0119] Step 1: The node determines whether it has data to send. If not, it does nothing; if so, it proceeds to Step 2.

[0120] Step 2: The source RN determines whether the destination RN is a node that is currently communicating in the network. If so, it sets the current node as a high-priority node and sets the initial value of retry_count. If not, it sets the current node as a low-priority node and sets the initial value of retry_count.

[0121] Step 3: The node listens to see if the channel is idle. If the channel is busy, it continues to listen; if the channel is idle, it proceeds to step 4.

[0122] Step 4: After the source RN waits for the DIFS duration, it sends an RTS frame omnidirectionally on the 5G channel and determines whether the source RN has received the CTS frame sent by the destination RN. If no CTS frame is received, proceed to step 5; if a CTS frame is received, proceed to step 6.

[0123] Step 5: Set the retry_count values ​​for high-priority nodes and low-priority nodes according to the method described above. If the retry_count value of the low-priority node is greater than the maximum backoff count or the retry_count value of the high-priority node is equal to the maximum backoff count, end the current channel reservation process; otherwise, recalculate the backoff duration, listen to the channel again, and wait for the channel to become idle.

[0124] Step 6: The source RN determines the priority setting type of this node. If it is a high-priority node, proceed to step 7; if the node is a low-priority node, wait for the destination RN to finish transmitting or receiving data before proceeding to step 7.

[0125] Step 7: The source RN and the destination RN align their antennas using beamforming, and then transmit a TTS test frame directionally on the THz channel. If the source RN does not receive an ACK frame from the destination RN, the current channel reservation process ends; if it receives an ACK frame from the destination RN, the source RN sends a data frame to the destination RN, and the destination RN replies with an ACK frame after receiving the data frame.

[0126] Step 8: After the source RN and the destination RN have finished communicating, the high-priority node resets the retry_count value to 0 according to the original BEB algorithm; the low-priority node randomly selects a value in the range [0, retry_count] as the initial value for the node to initialize retry_count in the next round.

[0127] Specific embodiments of the technical implementation of the present invention

[0128] Node operations are divided into two categories: source RN and destination RN. This section illustrates specific implementation examples by giving the main node operations for each time period.

[0129] Source RN main operations

[0130] The main operations of the source RN during the control interaction process are as follows:

[0131] (1) Before sending a control frame, the source RN determines whether to include location information in the control frame based on whether the node's location information has changed. If the node's location has changed, a control frame with location information is sent; otherwise, a control frame without location information is sent.

[0132] (2) At the same time, the node determines whether it can immediately send data to the destination RN after successfully competing for the channel. If it can, the node is set as a high-priority node; if it cannot, the node is set as a low-priority node.

[0133] (3) The node sends an RTS control frame.

[0134] (4) Switch to THz channel. After beamforming, decide whether to send data immediately or wait for a period of time to send data based on the priority of the node.

[0135] The operation process of the source RN is as follows Figure 6 As shown.

[0136] The main operation of RN

[0137] The main operations of nodes other than PNC during the Beacon period are as follows:

[0138] (1) Receive RTS frames.

[0139] (2) Determine whether the RTS frame carries location information and control frame priority.

[0140] (3) If the RTS frame does not carry location information, it means that the location of the source RN has not changed. The location information of the source RN stored in the location information storage table maintained by the destination RN can be used directly.

[0141] (4) If the RTS frame carries location information, then use the location information directly for beamforming.

[0142] (5) Switch to THz channel. After beamforming, decide whether to receive data immediately or wait for a period of time to receive data based on the priority of RTS frame.

[0143] The flowchart of the RN operation is as follows: Figure 7 As shown.

[0144] Beneficial effects of the technical solution of this invention

[0145] The beneficial effects of the technical solution of this invention are mainly reflected in the following two aspects:

[0146] During control information exchange, for nodes whose location information has already been broadcast and whose location has not changed when re-booking the channel, the control overhead during the control exchange process is reduced by decreasing the location information in the control frame. By setting priorities, nodes that can transmit in parallel have a greater chance of successfully competing for the channel, allowing more data to be transmitted on the THz channel at the same time, thus improving channel utilization and throughput.

[0147] Key technical points and points to be protected in this invention

[0148] The key technical points and points to be protected in this invention are:

[0149] Each node in the network maintains a location information storage table to store the location information that the node has broadcast in the network. The node's location information can be quickly obtained by looking up the table.

[0150] During the control interaction, whether or not the location information field in the control frame is omitted is determined by whether or not the location information changes, thereby reducing the control interaction time and increasing the time for data transmission on the THz channel.

[0151] By setting priorities for nodes, the success rate of data nodes competing for channels in parallel is increased, channels are reserved in advance, and the utilization rate of THz channels is improved.

[0152] The concept of this invention can also be used for:

[0153] (1) Parallel data transmission between nodes in a terahertz wireless ad hoc network;

[0154] (2) Reduce control overhead in terahertz wireless self-organizing networks.

[0155] The systems, devices, modules, or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions.

[0156] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0157] The above embodiments should be understood as illustrative only and not as limiting the scope of protection of the present invention. After reading the description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent changes and modifications also fall within the scope defined by the claims of the present invention.

Claims

1. A high-efficiency high-bandwidth utilization rate terahertz wireless network directional access control method, characterized in that, Includes the following steps: The design of a memory-assisted control interaction method is as follows: For nodes that are performing control information interaction for the first time in the network or retransmitting a control frame after the first failed transmission, the control information interaction process in the TAB-MAC protocol is followed; for nodes that have successfully communicated, if the node needs to transmit or receive data at a certain moment and its own node location information has not changed, the location information field in the control frame is removed; for nodes that have successfully communicated, if the location information of both the source and destination nodes has changed, the updated location information is broadcast omnidirectionally to all nodes in the network through the Sub-6G frequency band. After receiving the new location information of the node, the other nodes update the location information entries in their own location information storage table and perform the control interaction process according to the original protocol. Design a priority-based channel reservation method: After a node in the network successfully reserves a channel, the other nodes can start the next round of channel reservation. That is, all nodes except the nodes that are communicating can reserve channels. If the node reserving the channel does not affect the data transmission of the node that is communicating, then the node is set as a high-priority node, while the other nodes that affect the node that is communicating are set as low-priority nodes and reserve channels normally. The specific operation steps of the memory-assisted control interaction method are as follows: Step A1: Each node in the network maintains its own location information storage table, which records the location information and MAC address information of all nodes in the network except itself. When the location information storage table of all nodes is initialized, all entries are set to NULL. Step A2: When the source RN needs to send data, the source RN determines whether this node is sending an RTS frame for the first time or retransmitting an RTS frame for the first time. If yes, proceed to step A3; otherwise, proceed to step A4. Step A3: The source RN sends an RTS frame with location information, and then proceeds to step A5; Step A4: The source RN determines whether the location information of this node has changed. If it has changed, it sends an RTS frame with the new location information. If nothing has changed, send an RTS frame with location information omitted. Step A5: After receiving the RTS frame, the destination RN extracts the information carried in the RTS frame. If there is no location information in the RTS frame, it means that the location information of the source RN has not changed, and the destination RN directly uses the source RN location information stored in the local node location information storage table. Otherwise, use the location information carried in the RTS frame; Step A6: The destination RN determines whether this node is responding to a CTS frame for the first time or retransmitting a CTS frame for the first time. If so, it responds with a CTS frame containing the destination RN's location information. If not, reply with a CTS frame without location information; Step A7: After the source RN and the destination RN successfully exchange control information, both the source and destination RNs have obtained the location information and antenna information of the other node. The source and destination RNs switch to the THz channel and beamforming makes the THz directional antennas align with each other. The source RN sends a TTS frame in the THz channel. After receiving it, the destination RN replies with an ACK frame in the direction. Subsequently, the source RN uses a directional antenna to transmit data to the destination RN on the THz channel. After receiving the data frame and confirming that the data frame is correct, the destination RN replies to the source RN with an ACK frame. The specific operation steps of the priority-based channel reservation method are as follows: Step B1: The node determines whether it has data to send. If not, it does nothing; if so, it proceeds to step B2. Step B2: The source RN determines whether the destination RN is a node currently communicating in the network. If so, it sets this node as a high-priority node and sets... The initial value; if not, set this node as a low-priority node and set... The initial value; Step B3: The node listens to see if the channel is idle. If the channel is busy, it continues to listen; if the channel is idle, it proceeds to step B4. Step B4: After the source RN waits for the DIFS duration, it sends an RTS frame omnidirectionally on the 5G channel and determines whether the source RN has received the CTS frame sent by the destination RN; if the CTS frame is not received, proceed to step B5. If a CTS frame is received, proceed to step B6; Step B5: Configure high-priority and low-priority nodes The value, if it is a low-priority node Value greater than the maximum backoff count or higher priority nodes When the value equals the maximum number of backoffs, the current channel reservation process ends; Conversely, recalculate the backoff time, re-listen to the channel, and wait for the channel to become idle; Step B6: The source RN determines the priority setting type of this node. If it is a high-priority node, proceed to step B7; if the node is a low-priority node, wait for the destination RN to finish transmitting or receiving data before proceeding to step B7. Step B7: The source RN and the destination RN align their antennas using beamforming, and then a TTS test frame is transmitted directionally on the THz channel. If the source RN does not receive an ACK frame from the destination RN, the current channel reservation process ends. If an ACK frame is received from the destination RN, the source RN sends a data frame to the destination RN, and the destination RN replies with an ACK frame after receiving the data frame. Step B8: After the source RN and destination RN have completed communication, the high-priority node will... The value is reset to 0 according to the original BEB algorithm; low-priority nodes are then... Randomly select a value from the range as the initialization value for this node in the next round. The initial value.

2. The high-efficiency, high-bandwidth utilization terahertz wireless network directional access control method according to claim 1, characterized in that, The location information storage table is used to record all nodes in the network that have broadcast their location information and MAC address information omnidirectionally in the low-frequency band. The location information storage table has three entries: sequence number, node location information, and node MAC address information. The sequence number records the order in which all nodes in the network first broadcast control information via control frames. When a node sends an RTS control frame omnidirectionally in the Sub-6G band, the destination node will also reply with a CTS control frame. Therefore, each node can add the location information and MAC address information of the source node and the destination node to the location information storage table maintained by this node.

3. The high-efficiency, high-bandwidth utilization terahertz wireless network directional access control method according to claim 1, characterized in that, In the priority-based channel reservation method described above: in order to give nodes that can transmit in parallel a greater probability of successfully competing for the channel, nodes that can transmit in parallel are set as high-priority nodes, while nodes that cannot transmit in parallel and can only communicate after waiting for the nodes that are currently communicating to finish transmitting or receiving data are set as low-priority nodes. The core of setting priority nodes is the value of bit b4 in the frame control field. When the value of bit b4 is 0, it indicates that the node sending the frame is a low-priority node, and vice versa when it is 1, it is a high-priority node.

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