Adaptive neighbor discovery method and device for wireless ad hoc network based on data amount to be sent

Abstract

The application provides a wireless self-organizing network adaptive neighbor discovery method and device based on data amount, wherein the method is run in an initialization stage and a neighbor discovery stage of a subsequent time frame of network operation, and the operation of the method is performed by nodes in the network; the method comprises the following steps: selecting a single-node or multi-node beam transmission scanning mode according to the relationship between the number of nodes and the number of binary address bits of the nodes, increasing the number of scanning sub-stages of the neighbor discovery stage on demand based on the risk of beamforming frame collision, and enabling the nodes to adaptively control the execution of beam transmission scanning based on their own data amount in the process of neighbor discovery; thereby, whether in a wireless self-organizing network application occasion with a large number of nodes or a wireless self-organizing network application occasion with a small number of nodes, the control overhead can be reduced as a whole, the probability of beamforming frame collision and the probability of neighbor discovery failure can be reduced, and the time slot utilization rate of the wireless channel can be improved and the average end-to-end data packet delay can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wireless ad hoc networks (WANETs), and particularly relates to a distributed wireless ad hoc network application scenario using directional antennas for wireless signal transmission and reception and multi-hop data packet transmission. The present application can be widely applied in the field of communication technology, and is particularly suitable for occasions requiring instant and flexible communication, such as emergency rescue, military operations or remote area communication, etc. BACKGROUND

[0002] In the past two decades, the Internet has experienced a rapid development, and wired and wireless networks have covered all aspects of people's lives. Network performance has been greatly improved compared with two decades ago. As a result, people are no longer satisfied with traditional network usage scenarios and begin to seek more convenient and efficient new networks. In terms of network composition, people hope that new networks can be freed from routers, switches and other basic network devices, and can be quickly networked without relying on any communication infrastructure. Wireless terminals can complete network establishment, maintenance and information transmission through mutual cooperation. Wireless ad hoc network related technologies have experienced rapid development under this demand and have become an important research direction for the development and innovation of the mobile communication field.

[0003] In the military field, the technical characteristics of wireless ad hoc network, such as rapid deployment, flexible networking and self-organizing communication, are particularly suitable for military use scenarios such as unmanned aerial vehicles or military tactical teams, providing fast, flexible and stable network support for military activities. In the civil field, wireless ad hoc network devices are simple to arrange and easy to network, and can be used to provide reliable communication support for emergency rescue, disaster response, intelligent traffic management, smart cities, large outdoor activities and other related scenarios.

[0004] In the past decades when wired communication is developing rapidly, the development and application of wireless communication technology has been limited by the problems such as limited spectrum resources, wireless signal attenuation, security and privacy, energy constraints, standardization difficulties, etc. In the 1980s, due to the need for cooperative communication in battlefield environment without fixed infrastructure, researchers began to explore wireless ad hoc network technology to achieve reliable communication and information exchange in an environment without central node control. Until around 2010, wireless ad hoc network technology gradually began to be verified in practical applications, and the application scenarios were not limited to the military field, but also extended to emergency rescue, disaster recovery and wireless sensor network, and the standardization work of some self-organizing network protocols was gradually improved during this period. Abroad, IEEE and 3GPP organizations actively promote the standardization of self-organizing networks; in China, the Ministry of Industry and Information Technology formulates specifications and standards for emergency communication supported by self-organizing networks. But in the past few years of the Internet of Things era and the rapid development of the 5G era, wireless ad hoc network technology has become crucial in connecting a large number of Internet of Things devices, low latency, high reliability, and large capacity scenarios, and has received more attention. From the slow development and standardization process of wireless ad hoc network technology at home and abroad, it can be seen that the standardization work of self-organizing networks is still in the process of continuous development and research, and there are still many details to be improved in terms of network performance, management, security, and interoperability with other networks.

[0005] The antenna selection of wireless ad hoc network has a significant impact on network performance and protocol implementation. Directional antennas can provide longer transmission distance, higher signal gain and spatial multiplexing, and reduce mutual interference between adjacent nodes, and are considered to be able to significantly improve the total throughput and performance of the network. The advantage of omnidirectional antenna is that it can be represented as a 360° uniform radiation antenna in the horizontal direction, which greatly reduces the workload of discovering neighbors in a network without prior information. This feature makes wireless ad hoc network media access control protocols based on omnidirectional antennas simpler to implement and more suitable for highly dynamic and distributed network scenarios. Therefore, most existing wireless ad hoc network MAC protocols use omnidirectional antennas for data transmission and reception. However, as mobile terminal devices become smaller and network coverage becomes larger, the effective communication distance of nodes and the power constraints of nodes become particularly prominent. In order to solve these problems, researchers at home and abroad are gradually replacing omnidirectional antennas with directional antennas in the study of wireless ad hoc network protocols. The introduction of directional antennas into wireless ad hoc networks also brings a series of challenges to network protocol design, such as: directional antennas in node networks need frequent beam alignment; it is difficult to discover neighbors when nodes have no prior information; the matching degree of existing related MAC protocols with directional antennas is poor, and existing protocol mechanisms need to be adjusted or new protocols need to be redesigned; the implementation of beam rotation devices is complex, increasing the production cost of mobile nodes.

[0006] In recent years, researchers have been paying close attention to the development and application of wireless ad hoc networks. Commonly distributed wireless ad hoc networks do not contain a central node, all nodes are in the same position and nodes can be randomly distributed, and each node only needs to pay attention to the orientation information of its neighbors within the communication range and the frame transmission collision problem in the media access control layer. A typical wireless ad hoc network is shown in FIG. 1. Figure 1

[0007] The movement of nodes and the rapid change of topology make it difficult for existing directional antenna-based wireless ad hoc networks to achieve beam alignment in the neighbor discovery phase, which in turn leads to low network transmission success rate. Therefore, how to optimize the traditional directional antenna wireless ad hoc network TDMA protocol to make it suitable for high-speed mobile networks has become an important direction for wireless ad hoc network standardization.

[0008] The neighbor discovery phase and the time slot reservation phase are the most basic link to achieve collision-free communication between neighbor nodes, and are also the key to the design of distributed TDMA protocol for wireless ad hoc networks, so researchers have carried out in-depth research on them.

[0009] Xu X et al. proposed a typical directional antenna-based wireless ad hoc network distributed TDMA scheme - DTSA (Dynamic Time Slot Allocation), see literature: Xu X, Song Z, Zhang Z. Dynamic Time Slot Allocation for Mobile Ad Hoc Networks using Directional Antennas [C]. 2022IEEE 6th Information Technology and Mechatronics Engineering Conference, 2022: 2061-2066); DTSA divides the channel time into multiple continuous time frames, each time frame contains a neighbor discovery phase and multiple combinations of "time slot reservation phase + data transmission phase", the time frame structure is shown in FIG. 2. The neighbor discovery phase is used to find all the neighbor nodes for each node, the state of each node in this phase is shown in FIG. 3 (the node performing the operation to discover neighbors is called "neighbor discovery node"). Figure 2 Figure 3 max max max max B max ​​​​​​​​; for example, B is 16, i.e. B = 16, then N max = 2 B = 2 16 = 65536); each node performs beamforming in one or more scanning sub-phases, and completes beam alignment with neighbors through a three-way handshake to achieve neighbor discovery. When performing beamforming, the node broadcasts a beam scanning frame in each sector (when scanning in a two-dimensional plane with a directional antenna, 360 degrees is usually divided into multiple sectors of the same angle; for example, each sector is 45 degrees, so it is divided into 8 sectors); if a neighbor node in the sector receives the beam scanning frame, it sends a beam reply frame in reply; after receiving the beam reply frame, the current node sends a beam acknowledgement frame, thereby completing the three-way handshake. When the upper layer has data to arrive at the MAC sub-layer, the MAC sub-layer performs time slot reservation according to the traffic load and neighbor situation; after time slot reservation and allocation are completed, the node selects a time slot for data transmission according to the reservation result. Each scanning sub-phase of the neighbor discovery phase of the DTSA corresponds to one bit of the binary address of the node, and the scanning round (a scanning sub-phase is referred to as a "round") corresponds to the binary address bit of the node. B scanning sub-phases correspond to B bits (B = log2N, N is the maximum number of nodes that can be accommodated in the address space of the network node); the node determines whether to perform beam transmission scanning in the scanning sub-phase according to whether the 1 bit of the (own) binary address corresponding to the scanning sub-phase is 1 (the meaning of "beam transmission scanning" is that the wireless transceiver of the physical layer of the node is in a transmitting state, and the pointing of the rotating directional antenna beam broadcasts the beam scanning frame in each sector): if it is 1, beam transmission scanning is performed; if it is 0, beam reception scanning is performed (the meaning of "beam reception scanning" is that the wireless transceiver of the physical layer of the node is in a receiving state, and the pointing of the rotating directional antenna beam receives the beam scanning frame in each sector), and the sector in which the pointing of the directional antenna beam is changed is rotated to wait for the beam scanning frame. The neighbor discovery method of the DTSA allows multiple nodes to perform beam transmission scanning in one scanning sub-phase, and allows one node to perform beam transmission scanning in multiple scanning sub-phases; therefore, in the distributed TDMA protocol based on directional communication, compared with the neighbor discovery idea of allocating a scanning sub-phase to each node, the neighbor discovery method of the DTSA brings about redundant control overhead (the node may unnecessarily transmit a beam scanning frame) and the risk of neighbor discovery failure (the beam scanning frame or the beam reply frame may collide), but it provides a clever and feasible solution for quickly completing neighbor discovery, which helps to shorten the time for neighbor discovery, and is especially suitable for wireless ad hoc network scenarios with a large number of nodes.

[0010] Liu Q et al. proposed a mobile ad hoc network access control protocol based on directional antenna-DAND-MAC (see the literature: Liu Q, Hao Q, Ouyang F. Mobile Ad Hoc Network Access Control Protocol Based on Directional Antenna[J]. Journal of Beijing Jiaotong University, 2017, 41(02): 72-78, 84); the protocol can flexibly coordinate the use state of directional antenna and omnidirectional antenna. DAND-MAC protocol divides time into continuous repeating epochs, and omnidirectional antenna and directional antenna use different epoch structure. In the neighbor discovery phase, DAND-MAC protocol uses omnidirectional antenna to complete neighbor discovery and broadcast function. Each node has a fixed time slot to send HELLO packet in the neighbor discovery frame, and the HELLO packet contains the node's own coordinate and node information. After receiving the HELLO packet, the surrounding node will calculate the node's location angle according to the content to determine the node's location direction. In the link establishment phase, the protocol uses directional antenna. Each epoch is divided into link establishment time slot and data time slot. In the link establishment time slot, the protocol allocates at least one fixed time slot for each node to establish link and ensure the fairness of link establishment. While the establishment and release of time slot rely on the interaction of both parties in the link establishment time slot to select the common idle time slot from the idle time slots of both parties. DAND-MAC protocol is superior to traditional TDMA protocol in end-to-end delay, service rate and throughput, but the combination of omnidirectional antenna and directional antenna design makes the energy waste of node serious.

[0011] Zhang Z et al. introduced a kind of deterministic directional antenna scanning algorithm based on scanning—SBA (Scan-Based Algorithm; see the literature: Zhang Z, Li B. Neighbor discovery in mobile ad hoc self-configuring networks with directional antennas: algorithms and comparisons [J]. IEEE Transactions on Wireless Communications, 2008, 7(5): 1540-1549); the mechanism allocates a transceiving sequence to each node according to the node ID, and the transceiving sequence is used to mark each node and the transceiving role of each node in each scanning round, and the neighbor relationship between nodes is established through three-way handshake. In the network using the scanning-based deterministic directional antenna beamforming mechanism, at most log2N scanning is needed for any two nodes to complete the beamforming between nodes, where N is the maximum number of nodes in the network. This mechanism reduces the number of scanning rounds required for the nodes in the whole network to complete beamforming, and improves the efficiency of neighbor discovery, but multiple nodes send announcement information in parallel in each scanning round, and the network is prone to collision and interference on the receiving side, thereby increasing the probability of neighbor discovery failure. Yang et al. proposed a bidirectional carrier sense collision avoidance algorithm—BD-SBA (Bi-directional Scan-Based Algorithm; see the literature: Yang A, Li B, Yan Z, et al. A bi-directional carrier sense collision avoidance neighbor discovery algorithm in directional wireless ad hoc sensor networks [J]. Sensors, 2019, 19(9): 2120) on the basis of SBA algorithm; each node needs to perform carrier sensing and backoff before being selected as a sending node, and the node randomly selects a backoff value, and if no channel interference is detected during the backoff process, it enters the sending mode, and if there is channel interference, it is set to the receiving mode. This optimized algorithm solves the collision problem caused by parallel scanning of SBA, but the use of backoff will cause the neighbor discovery process to be too long, waste time slot resources and make the network delay uncontrollable.

[0012] Sorribes et al. proposed two deterministic collision avoidance neighbor discovery protocols, TDMA-based protocol and Leader-based protocol (see the literature: Sorribes J V, L, Lloret J, et al. Collision Avoidance Based Neighbor Discovery in Ad Hoc Wireless Networks [J]. Wireless Personal Communications, 2022: 1-25); the Leader-based neighbor discovery algorithm stipulates that a node is randomly selected to be a Leader at the beginning of a time slot, and the Leader node broadcasts a neighbor discovery frame in each sector in the next time slot to discover neighbors. All non-Leader nodes quickly switch the receiving antenna within the transmission sector dwell time until they receive the broadcast frame, and then select a fixed time slot to respond to the ACK frame according to the node ID. The Leader node updates the neighbor table after receiving the ACK frame, and broadcasts the obtained neighbor table to its neighbors when the Leader node completes the beamforming in all sectors. The TDMA-scheduled neighbor discovery method is similar to the Leader-based neighbor discovery algorithm, and the former replaces random Leader election with TDMA scheduling, and each node only performs neighbor discovery in its occupied time slot. The two neighbor discovery algorithms proposed by Sorribes et al. use a backoff method to avoid the collision problem in the neighbor discovery process, and the time complexity of the node to discover all neighbors is O(N) and O(N 2 ), respectively, but this mechanism can only be applied to single-hop static networks, and has a high requirement for time synchronization of nodes.

[0013] Hu Zhengfeng and Wang Jian proposed a neighbor discovery algorithm based on binary code sequence (see the literature: Hu Zhengfeng, Wang Jian. A neighbor discovery algorithm for directional wireless ad hoc networks [J]. Telecommunications Technology, 2022, 62(11): 1663-1669); the algorithm sets a binary code sequence for each node, and the node determines the current transceiver mode of the node through the binary code sequence. The algorithm uses the mathematical rule that the Hamming distance between any two code sequences is greater than or equal to 1 to ensure that any pair of nodes is in a transmit-receive state at a certain time during the scanning process. The transmitting antenna of the transmitting node stays in one transmitting sector for K transceiver micro time slots (K is the number of antenna sectors), and the receiving antenna of the receiving node rotates a full circle during the transmitting antenna residence period. The transmitting node discovers all neighbors of the receiving node after K×K transceiver micro time slots. The neighbor discovery algorithm based on binary code sequence will cause multiple transmitting nodes to transmit data at the same time according to the code word, thereby increasing the probability of network collision and affecting network quality. In addition, the beamforming mechanism used in the neighbor discovery algorithm based on binary code sequence can ensure that each node does not miss neighbor nodes during the neighbor discovery process, but the node discovery efficiency is low and there is a certain optimization space.

[0014] In the MAC protocol of wireless ad hoc networks based on directional antennas, the beamforming scanning mode and the handshake mechanism determine the efficiency of the neighbor discovery phase. Liu et al. proposed a hybrid three-way handshake synchronization algorithm—HAS-3-way (Hybrid 3-way handshake Synchronous Algorithm; see the literature: Liu Y, Feng Z, Han C, et al. Hybrid 3-way neighbor discovery algorithm in UAV networks with directional antennas [C]. 2018 IEEE 29th Annual International Symposium on Personal, Indoor and Mobile Radio Communications, 2018: 1163-1168); HAS-3-way algorithm divides nodes into active state, passive state and stop state, and nodes in active state use three-way handshake to complete neighbor discovery. After sending the HELLO frame, the sending node waits for the receiving node to reply the feedback, and after receiving the feedback information of the receiving node, the sender sends an acknowledgement frame. This process is called neighbor discovery three-way handshake. When the neighbor node confirms that it has been discovered by the discovered node, it will stop sending unnecessary handshake packets. The hybrid three-way handshake synchronization algorithm reduces the collision probability during the three-way handshake and reduces the expected time to discover all neighbors.

[0015] From the above research background and status, it is not difficult to see that people have carried out a period of research on the neighbor discovery method of the directional antenna-based wireless ad hoc network MAC protocol, and have made some progress. However, through in-depth research, it can be found that the existing typical neighbor discovery method of the directional antenna-based wireless ad hoc network distributed TDMA protocol represented by the DTSA still has the following problems:

[0016] (1) When the binary address of the node has B bits, B scanning sub-stages will be set in the neighbor discovery stage; if the total number of nodes N in the network is less than B, the number of scanning sub-stages will be redundant, and it is better to directly allocate 1 scanning sub-stage to each node.

[0017] (2) Since there can be multiple nodes broadcasting beam scanning frames or multiple nodes sending beam reply frames in one scanning sub-stage (1 scanning sub-stage corresponds to 1 round of scanning), beamforming will fail due to frame collision in some cases. For example, considering the case of 4 nodes, their addresses are 00, 01, 10, and 11 in binary, if the positions of the nodes 00, 01, and 11 are approximately on a straight line, then in the first round of scanning, the beam reply frames sent by the nodes 00 and 01 will collide at the node 11, and in the second round of scanning, the beam scanning frames broadcasted by the nodes 01 and 11 will collide at the node 00, thereby causing the beamforming between the nodes 00 and 11 to fail, and the result is that the neighbor discovery fails in some cases.

[0018] (3) In the B (B = log2N max ) scanning sub-stages of the neighbor discovery stage of one time frame, if the binary address of the node is 1, it will perform neighbor discovery (perform operations such as beam sending scanning and receiving beam reply frames) in the corresponding scanning sub-stage, regardless of whether it has data packets to send or whether it is necessary to do beamforming. If a node has no data or not enough data to send in a time frame, then all or part of the beamforming operations it does in the neighbor discovery stage of the time frame are unnecessary, which will bring about redundant control overhead and operations.

[0019] The above three problems will affect the effect and performance of the neighbor discovery method of the directional antenna-based wireless ad hoc network distributed TDMA protocol (such as neighbor discovery failure in some cases, and large control overhead), and further affect the data transmission performance of the wireless ad hoc network (such as large data packet transmission delay in some cases); in order to solve these problems, an innovative scheme will be proposed. SUMMARY

[0020] The application relates to a directional antenna-based distributed TDMA protocol working in a wireless ad hoc network, wherein nodes in the network use directional antennas for data transmission and reception, and the beam energy generated by the antennas is mainly concentrated on the main lobe; the network has no central node, all nodes are time-synchronized by an external system (such as a Beidou or GPS system) and complete time synchronization between nodes, and the nodes can be static or mobile. The directional antennas of the nodes scan in a two-dimensional plane; the signal transmission and reception of the directional antennas is in a half-duplex mode (antenna signal transmission and reception cannot be simultaneously performed). "Neighbour discovery" refers to finding all neighbour nodes of a node, and the function is realized by the node based on beamforming operation in a "neighbour discovery" stage of a time frame. Main operations for "carrying out neighbour discovery" include performing beam transmission scanning and receiving a beam reply frame; main operations for "cooperating with neighbour discovery" include performing beam receiving scanning and sending a beam reply frame after receiving a beam scanning frame. A typical case of sector division of antenna scanning of a neighbour discovery node and its neighbour nodes is shown in the accompanying drawings. Figure 4

[0021] In order to solve the problems of "redundancy of scanning sub-stage number when the node number is less than the node binary address bit number", "neighbour discovery failure in some cases" and "redundancy of control overhead in the neighbour discovery stage" of the neighbour discovery method of the directional antenna-based wireless ad hoc network distributed TDMA protocol described above, the application provides an adaptive neighbour discovery method based on the amount of data to be sent (hereinafter referred to as "new method") and a device for realizing the new method; the new method comprises three new mechanisms of "selecting a scanning mode based on the node number", "increasing a scanning sub-stage on demand" and "adaptive control of beam transmission scanning based on the amount of data to be sent"; the use of the new mechanisms in the new method can improve the neighbour discovery probability, reduce the control overhead and shorten the neighbour discovery time in some cases, thereby being beneficial to reducing the average end-to-end packet delay, improving the access protocol efficiency and time slot utilization. The address of the node related to the new method and the new mechanisms contained in the new method provided by the application refers to the MAC address of the node.

[0022] The new mechanism of "selecting a scanning mode based on the node number" can solve the problem of "redundancy of scanning sub-stage number when the node number is less than the node binary address bit number", can individually allocate a scanning sub-stage for each node when the total number of network nodes N is not greater than the binary address bit number B of the node, eliminate the collision of beamforming frames (including beam scanning frames and beam reply frames; the new method and the new mechanisms contained in the new method provided by the application do not use beam confirmation frames), ensure that all neighbour nodes can be discovered, and reduce the number of scanning sub-stages as a whole, which is beneficial to improving the time slot utilization.

[0023] ​The "increasing the number of scanning sub-phases on demand" mechanism aims at the "neighbor discovery failure in some cases" problem. When it is found that there is a risk of beamforming frame collision, it provides more beamforming opportunities for the nodes that fail in neighbor discovery by increasing the number of scanning sub-phases, thereby reducing the probability of neighbor discovery failure and the average end-to-end packet delay, and improving the time slot utilization.

[0024] The "adaptive control of beam transmission scanning based on the amount of data to be transmitted" mechanism aims to solve the "redundancy in control overhead in the neighbor discovery phase" problem. It allows the node to stop subsequent beam transmission scanning operations even if the neighbor discovery phase has not ended, provided that all the data frame destination nodes (which are also the neighbor nodes of the current node) that the node needs to find in a time frame have been found, thereby reducing the control overhead and the probability of beamforming frame collision.

[0025] The basic ideas, main operations and main operations of the new methods of the three new mechanisms are described in detail below.

[0026] (I) The basic ideas and main operations of the new mechanisms contained in the new method proposed in the present application

[0027] The "adaptive neighbor discovery method based on the amount of data to be transmitted" proposed in the present application contains three new mechanisms: "selecting a scanning mode based on the number of nodes", "increasing the number of scanning sub-phases on demand", and "adaptive control of beam transmission scanning based on the amount of data to be transmitted", which are composed as shown in the accompanying Figure 5

[0028] 1. Basic ideas and main operations of the "selecting a scanning mode based on the number of nodes" mechanism

[0029] The basic idea of the "selecting a scanning mode based on the number of nodes" mechanism is as follows: in the initialization, the node compares the total number of network nodes N (previously known) with the number of binary address bits B of the node; if N <= B, the "single node scanning mode" - "allocating a scanning sub-phase for each node, and only one node performs beam transmission scanning in each scanning sub-phase" is used in the subsequent neighbor discovery phase of the network operation, and the number of scanning sub-phases included in the neighbor discovery phase of the time frame is set to N; if N > B, the "multi-node scanning mode" - "each scanning sub-phase can have multiple nodes performing beam transmission scanning, and if the binary address bit of a node is 1, the node performs beam transmission scanning in the scanning sub-phase corresponding to the bit" is used in the neighbor discovery phase, and the number of scanning sub-phases included in the neighbor discovery phase of the time frame is set to B. A prerequisite for using the "single node scanning mode" is that the values of the addresses of all nodes in the network are increasing without omission at equal intervals (such as an interval of 1) from a value (such as 0).

[0030] ​The new mechanism "select scan mode based on node number" works in the initialization phase of the network (the network running time is divided into an initialization phase and a plurality of continuous time frames), and is executed by each node in its MAC sub-layer (part of the network's Layer 2 - Data Link Layer); the main operations are as follows:

[0031] N1_1: The node obtains the number of bits B of its own binary address (referring to the MAC address represented in binary).

[0032] N1_2: The node determines: are the values of all node addresses evenly and regularly increasing from a value without omission? If yes, it means that the single-node scan mode can be used, and the next step is executed; if no, it means that the single-node scan mode cannot be used, and N1_5 is executed.

[0033] N1_3: The node compares B and the pre-known total number of network nodes N, and determines: is N≤B? If yes, the next step is executed; if no, N1_5 is executed.

[0034] N1_4: The node determines to use the "single-node scan mode" in the neighbor discovery phase of the time frame, and sets the number N of scan sub-phases contained in the neighbor discovery phase of the time frame S = N; then the operation ends.

[0035] N1_5: The node determines to use the "multi-node scan mode" in the neighbor discovery phase of the time frame, and sets the number N of scan sub-phases contained in the neighbor discovery phase of the time frame S = B; then the operation ends.

[0036] 2 Basic idea and main operations of the new mechanism "increase scan sub-phase number on demand"

[0037] The basic idea of the new mechanism "increase scan sub-phase number on demand" is: in the initialization, the node compares the average number of neighbors N a and the number of sectors F to determine whether there is a risk of beamforming frame collision (if there are multiple neighbor nodes in one sector of the node, there is a risk of beamforming frame collision, which will cause neighbor discovery failure); if there is a risk, the number of increased scan sub-phases is determined according to the number relationship between N a and F, and the number of scan sub-phases contained in the neighbor discovery phase is increased; in addition, in order to end the neighbor discovery phase as soon as possible, the number of increased scan sub-phases is set with an upper limit. After the number of scan sub-phases is increased, it can remain unchanged or be adjusted as needed. The increased scan sub-phases are used by the nodes that have failed to find the destination node for all pending data packets (in the MAC sub-layer, the source and destination nodes of the pending data packet are neighbors) to continue the neighbor discovery operation.

[0038] The "increasing the number of scanning sub-phases on demand" new mechanism runs in the initialization phase of the network, and starts running after the "selecting scanning mode based on the number of nodes" new mechanism stops running; and is conditional: the "selecting scanning mode based on the number of nodes" new mechanism selects the "multi-node scanning mode", and can run.

[0039] The "increasing the number of scanning sub-phases on demand" new mechanism is executed by each node in its own MAC sub-layer; the main operations are as follows:

[0040] N2_1: The node calculates the average number of neighbors E of each node according to the network coverage area S obtained in advance, the total number of network nodes N, and the node communication range R. a The calculation formula is as follows:

[0041]

[0042] Where the operator represents rounding up, = the smallest integer not less than x.

[0043] N2_2: The node compares the average number of neighbors E a and the sector number F, and judges: E a >F? If true, it means that there is a risk of beamforming frame collision, and the next step is executed; if not, the operation is ended.

[0044] N2_3: The node calculates the scanning sub-phase number increase value A S ; A S is positively correlated with the difference E a -F between E a and F in general; linear or nonlinear methods can be used to calculate A S ; the recommended calculation formula is: A S =E a -F.

[0045] N2_4: The node sets the upper limit L S of the scanning sub-phase number increase value A S ; the value of L S is associated with the sector number F and the total number of network nodes N; 0<L S <(N-B); it is recommended to set L S =F.

[0046] N2_5: The node judges: A S >L S ? If true, let A S =L S ; otherwise, do not operate.

[0047] N2_6: Number of scanning sub-phases contained in the neighbor discovery phase of a node setting time frame S = B + A S ; then end operation.

[0048] 3 Basic idea and main operation of the new mechanism of "Beam transmission scan adaptive control based on the amount of data to be sent"

[0049] The basic idea of the new mechanism of "Beam transmission scan adaptive control based on the amount of data to be sent" is: the node performs neighbor discovery on demand within its own scanning sub-phase; and in the process of performing neighbor discovery, it adaptively controls the execution of beam transmission scan based on the amount of data to be sent.

[0050] The meaning of the scanning sub-phase belonging to the node is: for "single-node scanning mode", "the scanning sub-phase belonging to the node" refers to the scanning sub-phase corresponding to the node address; for "multi-node scanning mode", "the scanning sub-phase belonging to the node" refers to the scanning sub-phase corresponding to "1" in the binary address of the node, as well as the scanning sub-phase added after running the new mechanism of "increasing the number of scanning sub-phases on demand" proposed in this invention.

[0051] The meaning of "performing neighbor discovery on demand" is: if there are data packets to be sent in the transmission buffer of the node's MAC sub-layer, neighbor discovery is performed.

[0052] The meaning of "adaptively controlling the execution of beam transmission scan based on the amount of data to be sent" is: if all the destination nodes of the data packets to be sent in the transmission buffer of the node's MAC sub-layer have been found, or the total amount of data of the data packets to be sent whose destination nodes have been found can use up all the time slots of the subsequent first data transmission phase, the node terminates the beam transmission scan operation in the current neighbor discovery phase, i.e. does not perform beam transmission scan in the current neighbor discovery phase.

[0053] The new mechanism of "Beam transmission scan adaptive control based on the amount of data to be sent" runs in all scanning sub-phases of the neighbor discovery phase in the time frame, and the operation is performed by the neighbor discovery node in its own MAC sub-layer; the main operation is as follows:

[0054] N3_1: The node determines whether there are data packets to be sent in its own MAC sub-layer transmission buffer; if there are, the next step is executed; if there are not, it cooperates with neighbor nodes to perform neighbor discovery in each scanning sub-phase until the current neighbor discovery phase ends.

[0055] N3_2: The node determines whether the current scanning sub-phase is its own scanning sub-phase; if it is, the next step is executed; if it is not, go to N3_4.

[0056] N3_3: The node initiates the neighbor discovery operation and adaptively controls the execution of the beam transmission scan based on the amount of data to be sent; then, go to N3_5.

[0057] N3_4: The node performs neighbor discovery with the neighbor node.

[0058] N3_5: The node determines whether all scan sub-phases of the current neighbor discovery phase have been experienced; if yes, end the operation; if no, return to N3_2.

[0059] (II) Main operation and running device of the new method

[0060] The adaptive neighbor discovery method based on the amount of data to be sent is suitable for a wireless ad hoc network using directional communication and a distributed TDMA protocol, all nodes in the network use directional antennas for data transmission and reception, and the data transmission and reception cannot be performed simultaneously. The adaptive neighbor discovery method based on the amount of data to be sent contains three new mechanisms, i.e., "selection of a scan mode based on the number of nodes", "on-demand increase in the number of scan sub-phases", and "adaptive control of beam transmission scan based on the amount of data to be sent", and is used in the initialization phase of network operation and the neighbor discovery phase of subsequent time frames, and is executed by the MAC sub-layer of each node in the network.

[0061] 1 Main operation of the new method

[0062] The main operation of the adaptive neighbor discovery method based on the amount of data to be sent is as follows:

[0063] N_1: The node obtains the number B of bits of its own binary address.

[0064] N_2: The node determines whether the values of the addresses of all nodes are evenly and equally spaced from a value without omission; if yes, execute the next step; if no, go to N_5.

[0065] N_3: The node compares the total number N of network nodes known in advance and B, and determines whether N≤B; if yes, execute the next step; if no, go to N_5.

[0066] N_4: The node determines to use a "single-node scan mode" in the neighbor discovery phase of the time frame, and sets the number N of scan sub-phases contained in the neighbor discovery phase of the time frame S = N; then go to N_12.

[0067] N_5: The node determines to use a "multi-node scan mode" in the neighbor discovery phase of the time frame, and sets the number N of scan sub-phases contained in the neighbor discovery phase of the time frame S = B.

[0068] N_6: Based on the pre-obtained network coverage area S, the total number of network nodes N, and the node communication range R, each node calculates the average number of neighbors E. a The calculation formula is as follows:

[0069]

[0070] Operators Indicates rounding up. = The smallest integer not less than x.

[0071] N_7: Average number of neighbors compared to the node E a Given the number of sectors F, determine: E a >F? If true, proceed to the next step; if false, go to N_12.

[0072] N_8: Increase in the number of node-calculated scan sub-stages (A) S Recommended calculation formula: A S =E a -F.

[0073] N_9: Node setting increases the number of scan sub-stages by A. S Upper limit L S Recommended setting: L S =F.

[0074] N_10: Node determination: A S >L S If true, let A S =L S Otherwise, no action will be taken.

[0075] N_11: The number of scanning sub-phases N included in the neighbor discovery phase of the node setup frame. S =B+A S .

[0076] N_12: Node determination: Has the neighbor discovery phase of a new time frame been entered? If yes, proceed to the next step; if no, return to this step.

[0077] N_13: Node checks: Does its own MAC sublayer send buffer have any data packets to be sent? If yes, proceed to the next step; if not, cooperate with neighboring nodes to discover neighbors in each scan sub-stage until the current neighbor discovery stage ends, and then return to N_12.

[0078] N_14: Node determination: Is the current scan sub-stage its own scan sub-stage? If yes, proceed to the next step; if no, go to N_16.

[0079] N_15: The node initiates the neighbor discovery operation and adaptively controls the execution of beam transmission scanning based on the amount of data to be sent; then go to N_17.

[0080] N_16: The node cooperates with the neighbor node to perform neighbor discovery.

[0081] N_17: The node determines whether all scanning sub-phases of the current neighbor discovery phase have been experienced? If yes, return to N_12; if no, return to N_14.

[0082] The operation flow of the new method proposed in the present application is shown in the attached Figure 6 and the attached Figure 7 .

[0083] 2 The running device of the new method proposed in the present application

[0084] The device running the new method proposed in the present application is specifically as follows:

[0085] (1) An electronic device, comprising a memory, a processor and a computer program stored on the memory and executable on the processor; the processor implements the content contained in the adaptive neighbor discovery method based on the amount of data to be sent in the wireless ad hoc network as described in the above section when executing the program.

[0086] (2) A non-transitory computer readable storage medium, having a computer program stored thereon; the computer program is executed by a processor to implement the content contained in the adaptive neighbor discovery method based on the amount of data to be sent in the wireless ad hoc network as described in the above section.

[0087] (3) A computer program product, comprising a computer program; the computer program is executed by a processor to implement the content contained in the adaptive neighbor discovery method based on the amount of data to be sent in the wireless ad hoc network as described in the above section.

[0088] (Three) The beneficial effects of the new method proposed in the present application

[0089] The beneficial effects of the "adaptive neighbor discovery method based on the amount of data to be sent in the wireless ad hoc network" proposed in the present application are mainly: whether in the application scene of the wireless ad hoc network with many nodes or in the application scene of the wireless ad hoc network with few nodes, the control overhead can be reduced as a whole, the probability of beamforming frame collision and the probability of neighbor discovery failure can be reduced, thereby being beneficial to improve the time slot utilization rate of the wireless channel and reduce the average end-to-end delay of data packets.

[0090] In particular, the new mechanism of "selecting scanning mode based on node number" solves the problem of "redundancy of scanning sub-phase number when node number is less than node binary address bit number", and can individually allocate scanning sub-phase for each node when the total number of network nodes N is not greater than the binary address bit number B of the node, eliminate the collision of beamforming frame, ensure that all neighbor nodes can be discovered, and reduce the number of scanning sub-phase as a whole, which is conducive to improving the time slot utilization rate. The mechanism of "increasing scanning sub-phase number on demand" aims at the problem of "neighbor discovery failure in some cases". When there is a risk of beamforming frame collision, the number of scanning sub-phase is appropriately increased to provide more beamforming opportunities for nodes with neighbor discovery failure, thereby reducing the probability of neighbor discovery failure and the average end-to-end packet delay, and improving the time slot utilization rate. The new mechanism of "adaptive control of beam transmission scanning based on data amount to be sent" allows the node to terminate the beam transmission scanning operation in a time frame when all the destination nodes of the data frame that the node needs to find in the time frame have been found, thereby reducing the control overhead and the probability of beamforming frame collision. BRIEF DESCRIPTION OF DRAWINGS

[0091] FIG. 1 is a schematic diagram of a typical wireless ad hoc network. Figure 1 FIG. 2 is a schematic diagram of a time frame structure used in the DTSA scheme.

[0092] FIG. 3 is a schematic diagram of the state of each node in the neighbor discovery phase of the DTSA scheme. Figure 2 FIG. 4 is a schematic diagram of a typical division of the antenna scanning sectors of a neighbor discovery node and its neighbor nodes.

[0093] FIG. 5 is a schematic diagram of the composition of the adaptive neighbor discovery method of the wireless ad hoc network based on the data amount to be sent. Figure 3 FIG. 6 is the upper half of the operation flowchart of the adaptive neighbor discovery method of the wireless ad hoc network based on the data amount to be sent.

[0094] Figure 4 FIG. 7 is the lower half of the operation flowchart of the adaptive neighbor discovery method of the wireless ad hoc network based on the data amount to be sent.

[0095] FIG. 8 is a schematic diagram of the composition of the adaptive neighbor discovery method of the wireless ad hoc network based on the data amount to be sent. Figure 5 FIG. 9 is the upper half of the operation flowchart of the adaptive neighbor discovery method of the wireless ad hoc network based on the data amount to be sent.

[0096] Figure 6 FIG. 10 is the lower half of the operation flowchart of the adaptive neighbor discovery method of the wireless ad hoc network based on the data amount to be sent.

[0097] FIG. 11 is a schematic diagram of the composition of the adaptive neighbor discovery method of the wireless ad hoc network based on the data amount to be sent. Figure 7 FIG. 12 is the operation flowchart of the adaptive neighbor discovery method of the wireless ad hoc network based on the data amount to be sent.

[0098] ​​​The wireless ad hoc network adaptive neighbor discovery method based on data amount to be sent provided by the application is applicable to the wireless ad hoc network using directional communication and distributed TDMA protocol, and runs along with the running of the distributed TDMA protocol.

[0099] A wireless ad hoc network comprising three or more nodes, the node being an electronic device using directional antenna and having wireless communication function, the node being equipped with external time device for realizing time synchronization by means of external system (such as Beidou system or GPS system). The wireless transceiver device and directional antenna of the node use half duplex mode, and can only send or receive wireless signal at the same time. All nodes in the network are logically in the same position. The MAC sub-layer of the network runs distributed TDMA protocol; the running time of the network is divided into initialization stage and multiple time frames after the initialization stage, each time frame comprising a neighbor discovery stage and multiple combination of "time slot reservation stage + data transmission stage". Through setting, the node knows the total number of network nodes, network coverage area, node communication range, whether single node scanning mode can be used and other information in advance.

[0100] The wireless ad hoc network adaptive neighbor discovery method based on data amount to be sent provided by the application is executed by each node, and runs in the initialization stage of the network and the neighbor discovery stage of the time frame. The main operation of the node is as follows:

[0101] E_1: the node obtains the bit number B of its own binary MAC address.

[0102] E_2: the node judges: are the values of addresses of all nodes starting from a value and increasing at equal intervals without omission? If yes, execute the next step; if no, turn to E_5.

[0103] E_3: the node compares the total number of network nodes N known in advance and B, and judges: is N≤B? If yes, execute the next step; if no, turn to E_5.

[0104] E_4: the node determines to use "single node scanning mode" in the neighbor discovery stage of the time frame, and sets the number N of scanning sub-stages contained in the neighbor discovery stage of the time frame S =N; and then turn to E_12.

[0105] E_5: the node determines to use "multi-node scanning mode" in the neighbor discovery stage of the time frame, and sets the number N of scanning sub-stages contained in the neighbor discovery stage of the time frame S =B.

[0106] E_6: Based on the pre-obtained network coverage area S, the total number of network nodes N, and the node communication range R, each node calculates the average number of neighbors E. a The calculation formula is as follows:

[0107]

[0108] Operators Indicates rounding up. = The smallest integer not less than x.

[0109] E_7: Node comparison average number of neighbors E a Given the number of sectors F, determine: E a >F? If true, proceed to the next step; if false, go to E_12.

[0110] E_8: Increase in the number of node-calculated scan sub-stages (A) S A S =E a -F.

[0111] E_9: Node setting increases the number of scan sub-stages by value A S Upper limit L S :L S =F.

[0112] E_10: Node determination: A S >L S If true, let A S =L S Otherwise, no action will be taken.

[0113] E_11: The number N of scan sub-phases included in the neighbor discovery phase of the node setup frame. S =B+A S .

[0114] E_12: Node determination: Has the neighbor discovery phase of a new time frame been entered? If yes, proceed to the next step; if no, return to this step.

[0115] E_13: Node checks: Does its own MAC sublayer send buffer have any data packets to be sent? If yes, proceed to the next step; if not, cooperate with neighboring nodes to discover neighbors in each scan sub-stage until the current neighbor discovery stage ends, and then return to E_12.

[0116] E_14: Node determination: Is the current scan sub-stage its own scan sub-stage? If yes, proceed to the next step; if no, go to E_16.

[0117] E_15: The node initiates a neighbor discovery operation and adaptively controls the execution of beam transmission scanning based on the amount of data pending transmission; then go to E_17.

[0118] E_16: The node cooperates with the neighbor node to perform neighbor discovery.

[0119] E_17: The node determines whether all scanning sub-phases of the current neighbor discovery phase have been experienced? If yes, return to E_12; if no, return to E_14.

[0120] The specific implementation of the device running the adaptive neighbor discovery method based on the amount of data pending transmission in the wireless ad hoc network proposed by the present application has:

[0121] (1) An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor; when the processor executes the program, the content contained in the adaptive neighbor discovery method based on the amount of data pending transmission in the wireless ad hoc network as described in the foregoing of this part is realized.

[0122] (2) A non-transitory computer-readable storage medium having a computer program stored thereon; when the computer program is executed by a processor, the content contained in the adaptive neighbor discovery method based on the amount of data pending transmission in the wireless ad hoc network as described in the foregoing of this part is realized.

[0123] (3) A computer program product comprising a computer program; when the computer program of the computer program product is executed by a processor, the content contained in the adaptive neighbor discovery method based on the amount of data pending transmission in the wireless ad hoc network as described in the foregoing of this part is realized.

Claims

1. A wireless ad hoc network adaptive neighbor discovery method based on the amount of data to be transmitted, characterized in that, The application relates to a node applied to a wireless self-organizing network, which comprises the following steps: in an initialization stage of network operation, when the address value of the node in the network is increased from a value without omission and at equal intervals, the node compares the total number N of nodes in the network with the binary address bit number B of the node to determine the beam transmission scanning mode adopted in the neighbor discovery stage of a time frame and set the number of scanning sub-stages contained in the neighbor discovery stage. Specifically, the size of the total number N of nodes and the binary address bit number B of the node is compared; if N<=B, the single-node scanning mode is adopted in the neighbor discovery stage of the time frame, that is, the mode of "allocating 1 scanning sub-stage for each node and only 1 node in each scanning sub-stage for beam transmission scanning" is used for neighbor discovery, and the number of scanning sub-stages contained in the neighbor discovery stage is set as N; if N>B, the multi-node scanning mode is adopted in the neighbor discovery stage of the time frame, that is, the mode of "multiple nodes in each scanning sub-stage for beam transmission scanning and the node binary address bit being 1 for beam transmission scanning in the scanning sub-stage corresponding to the bit" is used for neighbor discovery, and the number of scanning sub-stages contained in the neighbor discovery stage is set as B; in the initialization stage of the network, after the node determines that the multi-node scanning mode is adopted in the neighbor discovery stage of the time frame, the average number E of neighbors of the node and the number F of sectors are compared to judge whether there is a risk of beamforming frame collision, if there is a risk, the number of scanning sub-stages is increased according to the quantity relationship between E and F, and the number of scanning sub-stages contained in the neighbor discovery stage is increased; in order to end the neighbor discovery stage as soon as possible, the upper limit of the number of scanning sub-stages is set; in the neighbor discovery stage of the time frame after the initialization stage of the network operation, the node performs neighbor discovery in the scanning sub-stage belonging to itself as needed; and in the process of performing neighbor discovery, the execution of beam transmission scanning is adaptively controlled based on the amount of data to be sent. a And the number of sectors F is compared to judge whether there is a risk of beamforming frame collision, if there is a risk, the number of scanning sub-stages is increased according to the quantity relationship between E a And F, and the number of scanning sub-stages contained in the neighbor discovery stage is increased; in order to end the neighbor discovery stage as soon as possible, the upper limit of the number of scanning sub-stages is set; in the neighbor discovery stage of the time frame after the initialization stage of the network operation, the node performs neighbor discovery in the scanning sub-stage belonging to itself as needed; and in the process of performing neighbor discovery, the execution of beam transmission scanning is adaptively controlled based on the amount of data to be sent.

2. The adaptive neighbor discovery method for wireless ad hoc networks based on the amount of data to be transmitted according to claim 1, characterized in that, the average number of neighbors E of the compared nodes a and the number of sectors F, to determine whether there is a risk of beamforming frame collision, comprising: comparing the size of E a and F, if E a >F, indicating that some nodes' sectors contain more than one neighbor node, then it is considered that there is a risk of beamforming frame collision.

3. The adaptive neighbor discovery method for wireless ad hoc networks based on the amount of data to be transmitted according to claim 1, characterized in that, The number of scanning sub-phases is determined according to the number relationship between E a and F, and the number of scanning sub-phases contained in the neighbor discovery phase is increased, comprising: the node calculates a scanning sub-phase number increasing value A S , A S is the difference between E a and F; and the number of scanning sub-phases N a contained in the neighbor discovery phase is increased by A S . S ​ 4. The adaptive neighbor discovery method for wireless ad hoc networks based on the amount of data to be transmitted according to claim 1, characterized in that, The increasing number of scanning sub-phases sets an upper limit, including: the node sets the scanning sub-phase number increasing value A S The upper limit L S of the value of L S is associated with the number of sectors F, the total number of network nodes N.

5. The adaptive neighbor discovery method for wireless ad hoc networks based on the amount of data to be transmitted according to claim 1, characterized in that, The node performs neighbor discovery on demand in its own scanning sub-phase, including: when using single-node scanning mode, the node performs neighbor discovery in the scanning sub-phase corresponding to its own address if there is a data packet to be sent in the sending buffer of its MAC sub-layer; when using multi-node scanning mode, the node performs neighbor discovery in the scanning sub-phase corresponding to "1" in its own binary address and in the added scanning sub-phase if there is a data packet to be sent in the sending buffer of its MAC sub-layer.

6. The adaptive neighbor discovery method for wireless ad hoc networks based on the amount of data to be transmitted according to claim 1, characterized in that, The execution of the beam transmission scanning is adaptively controlled based on the amount of data to be sent, including: if all the destination nodes of the data packets to be sent in the sending buffer of the node MAC sub-layer have been found or the total amount of data of the data packets to be sent for which the destination nodes have been found can use all the time slots of the subsequent first data transmission phase, the node terminates the beam transmission scanning operation in the current neighbor discovery phase.

7. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor implements the steps of the wireless ad hoc network adaptive neighbor discovery method based on the amount of data to be sent according to any one of claims 1 to 6 when executing the program.

8. A non-transitory computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program implements the steps of the wireless ad hoc network adaptive neighbor discovery method based on the amount of data to be sent according to any one of claims 1 to 6 when executed by the processor.

9. A computer program product, comprising a computer program; the computer program implements the steps of the wireless ad hoc network adaptive neighbor discovery method based on the amount of data to be sent according to any one of claims 1 to 6 when executed by the processor.

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