A binary countdown medium access control method for wireless scenarios

Abstract

The application discloses a binary countdown medium access control method for wireless scene, and its competition process comprises the following steps: step 1, competition interval is carried out; step 101, each attempted access node generates a k-bit random number; step 102, the node makes corresponding action in the corresponding contention micro time slot according to each digit of the random number; step 103, a non-transmitting node generates a mask; step 104, the node which does not exit the competition is a winner node; step 2, all non-transmitting nodes send contention feedback messages to all winner nodes, and the winner node which succeeds in contention is a winner node; step 3, the winner node carries out data transmission. The application solves the hidden terminal problem by using the information mastered by the characteristic node, and improves the probability of conflict-free access.

Description

Technical Field

[0001] This invention belongs to the field of software technology and relates to wireless data transmission technology, specifically to a binary countdown medium access control method for wireless scenarios. Background Technology

[0002] Wireless Ad hoc Networks (WANETs) are autonomous systems composed of network nodes connected via wireless links. Nodes in the network are peer-to-peer, enabling wireless communication without the need for fixed infrastructure. During communication, nodes act as mobile terminals, generating traffic requests and transmitting data. Due to the limitations of radio range, physical broadcasts cannot cover all terminals, and multi-hop scenarios must be considered, where nodes simultaneously act as routers relaying data from other nodes. Because WANETs possess advantages such as self-establishment, self-organization, and self-management, they are suitable for applications in military battlefields, disaster search and rescue, environmental monitoring, autonomous driving, and healthcare—scenarios requiring rapid deployment of wireless networks without the need for base stations or fixed infrastructure.

[0003] Due to the highly variable environment, all protocols and coordination functions in WANET must be implemented entirely in a distributed manner, making it impossible to rely on a central controller to perform functions such as transmission synchronization or collision detection. Furthermore, due to the distributed nature of the environment, collisions between transmissions may only occur on a subset of receivers, a characteristic that further introduces the so-called hidden terminal problem.

[0004] Medium Access Control (MAC) protocols for WANET are mainly divided into two types based on the method of wireless channel access coordination: allocation-based and contention-based.

[0005] Allocation protocols require allocating resources to each node, and their implementation overhead is generally significant. Depending on the resources allocated, they can be categorized into types such as FDMA-based and TDMA-based protocols.

[0006] Allocation protocols refer to the fixed allocation of partitioned resources to specific nodes, generally ensuring that resources used by different nodes do not overlap. The advantages of fixed allocation protocols are that they guarantee fairness in data transmission among nodes and controllable protocol overhead. The disadvantages are that with a large network scale, the frame cycle period needs to be lengthened, leading to increased network latency; if there are few active nodes in the network, there will be too many idle resources; channel resources can only be fully utilized when the proportion of active nodes in the network is sufficiently large. Furthermore, fixed allocation protocols have the disadvantages of difficulty in implementing QoS support and low channel utilization.

[0007] In contention-based protocols, nodes can dynamically compete for resources based on different service requirements and channel occupancy. However, under heavy network load, the probability of collisions generated by traditional contention-based protocols increases significantly, as does the channel access latency for each node, leading to a rapid decline in protocol performance. A typical solution is to use CSMA and RTS / CTS to sense channel status and compete for access to the wireless channel; a representative protocol is 802.11p MAC.

[0008] The concepts described in this invention are explained as follows:

[0009] Binary Countdown Protocols, also known as Dominance Protocols, were originally proposed in the 1970s to resolve media access conflicts in wired networks. They have since evolved into an important class of algorithms for resolving arbitration problems and are applied in various fields.

[0010] Topology-transparent means that network nodes do not need to know the network topology. A protocol scheme that can operate without network nodes knowing the network topology is said to be topology-transparent.

[0011] The hidden node problem (Hidden terminal problem) occurs in the field of communications. When wireless node A sends information to node B, node C fails to detect that A is also sending information to B. As a result, A and C simultaneously send signals to B, causing a transmission collision. Ultimately, the signal sent to B cannot be decoded, and the information transmission of both A and C fails.

[0012] Time division multiple access (TDMA) is a communication technology used to enable shared transmission media (typically in the radio field) or networks. It allows multiple users to transmit data using the same frequency in different time slots (time slices).

[0013] "Try-Once-Discard" (TOD) is an architecture proposed for network control systems. It involves an arbitration process at a special stage to allow nodes to compete for access to the medium, after which they can switch to regular transmission and use the channel according to the competition result to transmit more data.

[0014] Binary Countdown Protocols, also known as Dominance Protocols, were initially proposed in the 1970s to resolve media access conflicts in wired networks and have since evolved into an important class of algorithms for resolving arbitration problems. The core idea is as follows: competing nodes (almost) simultaneously begin an arbitration process; during arbitration, each node transmits a unique, fixed-length bit sequence representing a priority value; these bit values ​​are encoded as dominant and recessive signals (such as high and low voltage levels on the wire). The characteristic of these signals is that if at least one node transmits a dominant signal, all nodes listening on the medium will observe the dominant signal; otherwise, it is a recessive signal. Competition is conducted bit-by-bit: when a node observes a dominant signal at a position where its signal is recessive, it stops transmitting, i.e., relinquishes the competition; otherwise, it continues transmitting the bit sequence. A node wins the competition when it successfully transmits its complete bit sequence.

[0015] One problem that needs to be addressed is that wireless network nodes generally cannot transmit and receive simultaneously; that is, they cannot listen on the medium during transmission. This can be achieved equivalently by transmitting only when the current sequence bit is dominant and receiving when it is recessive. Note that listening is unnecessary when a node's current sequence bit is dominant. Another problem is that contention between several nodes must begin (almost) simultaneously, which places high demands on synchronization. In single-hop wireless networks, the application of binary countdown is relatively straightforward, but in multi-hop wireless networks, further measures are needed due to synchronization challenges and the problem of hidden terminals.

[0016] The work of C.-H. Yeh and his team initially yielded two representative protocols: the BROADEN protocol and the CSMA / IC protocol. In the BROADEN protocol, a binary countdown protocol is applied before the transmission of control frames, which are used to schedule data frames on the data channel. BROADEN addresses the exposed terminal problem by having nodes negotiate the transmission power of data frames, while the arbitration of the binary countdown remains unchanged in single-hop networks, at the cost of high control overhead. The Carrier Induction Medium Access / ID Countdown (CSMA / IC) protocol is a binary countdown protocol that includes internal synchronization. Time is structured into a periodic synchronization phase and several "binary contention phases" to resolve the medium access contention problem. Its approach to addressing the hidden terminal problem is to set the sensing range to be at least twice the communication range, which requires fine-tuning of the transceiver and also exacerbates the exposed terminal problem.

[0017] Patent "200410097719.8 System and Method for Binary Countdown Media Access Control in Multi-Hop Wireless Free Networks" is an implementation of the aforementioned CSMA / IC protocol. In a multi-hop wireless network system, a system and method are used to perform binary countdown media access control by executing a contention code of non-repeating and unequal length within two hops. The wireless mobile device completes media access by competing for binary countdown based on the contention code, and relies on additional power control to adjust the sensing range, thereby solving the hidden terminal problem. The maximum number of bits in the contention code within two hops is obtained through periodic information broadcasting.

[0018] In some special application scenarios, such as building a network in a battlefield environment where pre-configuration is not possible, multiple wireless nodes power on at similar times but have no knowledge of the network situation and cannot configure the communication order on-site. Nodes randomly select time slots to send messages during the time frame period. Not only is the success rate of node transmission very low, but it is also difficult for nodes to be sure that there are no conflicts. In such an initial stage of network construction, it is quite difficult to quickly complete arbitration and finally form a conflict-free communication order under extremely scarce information.

[0019] Existing node access methods in wireless ad hoc networks, apart from contention-free pre-allocation, mostly rely on Carrier Sense Multiple Access (CSMA) and Request To Send / Clear To Send (RTS / CTS) mechanisms for contention-based access. Each access attempt may encounter an indefinite number of transmission collisions. ① Each collision means a failed access attempt. In modern wireless ad hoc networks with high-speed physical layer transmission capabilities, each collision means a significant bandwidth loss. ② As the number of competing access nodes increases, the probability of a successful access node decreases exponentially. This leads to a significant increase in successful access latency in scenarios with high node density and intense competition, making it difficult to support service quality. Summary of the Invention

[0020] To overcome the technical defects of the existing technology, this invention discloses a binary countdown medium access control method for wireless scenarios.

[0021] The binary countdown medium access control method for wireless scenarios described in this invention includes a time frame period comprising multiple time slots, which, from front to back, include a contention interval, a hidden terminal elimination interval, and a data interval; the contention interval includes k contention micro-time slots.

[0022] The control method includes a competition process for each time slot within each time frame period. The nodes participating in the competition process are all nodes within a single-hop collision domain. The competition process includes the following steps:

[0023] Step 1. Performed within the competition interval.

[0024] Step 101. For each node attempting to connect, generate a k-bit random number b = {bi}, i = (1, 2, ..., k);

[0025] Step 102. The node performs a corresponding action in the corresponding contention micro-slot based on each digit of the random number, specifically:

[0026] If bi=1, the node sends a contention signal CSi to contend for the channel;

[0027] Otherwise, if bi=0, node X listens to the channel;

[0028] During the channel monitoring process, if other nodes are detected contending for the channel, the node will relinquish the contention in that time slot and exit the competition.

[0029] Step 103. Define all nodes that have withdrawn from the contention as non-sender nodes. Each non-sender node listens to all contention signals CSi. When there is exactly one station transmitting in the j-th contention micro-slot, the non-sender node generates a mask. The mask is a k-bit string, with the j-th bit being 1 and all other bits being 0.

[0030] Step 104. Nodes that have not withdrawn from the competition proceed to Step 2 as the winning nodes;

[0031] Step 2.

[0032] If only one node remains in the competition after step 1, that node will be the winner and proceed directly to step 3.

[0033] Otherwise, proceed to step 201;

[0034] Step 201. All non-sender nodes send contention feedback messages to all winning nodes.

[0035] The contention feedback information includes a SID field indicating the time slot and an HCM field containing the mask generated in step 103;

[0036] Step 201.

[0037] Each winning node performs a bitwise AND operation between its k-bit random number and the mask in each HCM field. If all the results are non-zero, the contention is considered successful.

[0038] Use the successful winner node as the winner node to proceed to step 3;

[0039] Step 3. The winning node sends the victory information FI to the other nodes. The FI information contains the state information of each time slot in the time frame period that was previously known and the information of the time slot it has newly occupied. The other nodes update the state of each time slot in the time frame period according to the victory information FI.

[0040] The winning node transmits data.

[0041] Preferably, in step 201, the time for non-sender nodes to send contention feedback messages to all winning nodes is:

[0042] If the node is the one that relinquishes the contention, then the message is sent in the hidden terminal elimination interval;

[0043] If the node is the one performing node access, it will send the message in the time slot when the contention is successful.

[0044] Preferably, the hidden terminal elimination interval includes multiple elimination micro-time slots, and the node that relinquishes contention randomly selects one elimination micro-time slot to send.

[0045] Preferably, the non-sender node also includes the winner node of other time slots.

[0046] Preferably, the contention signal CSi is the MAC address information of the node.

[0047] The control method described in this invention has the following technical advantages over the prior art:

[0048] 1. During the contention process, not only do nodes awaiting access participate in information transmission, but nodes that have withdrawn from the contention can also participate in feedback. This leverages the information held by characteristic nodes to resolve the hidden terminal problem, increases the probability of conflict-free access, and accelerates the access process for all nodes in the network. Under arbitrary network node density and topology, this scheme, in the contention access phase, produces at least one successfully accessed node on average per contention. That is, the network node access latency is bounded and significantly better than general contention access mechanisms, especially in scenarios with high node density.

[0049] 2. Once all nodes have successfully accessed the network, each node acquires a conflict-free transmission channel. During subsequent regular transmissions, nodes will not experience collisions on their assigned channels unless network topology changes or other disasters cause physical layer channel changes. This approach is suitable for TOD (Transit-Oriented) architectures. In the early stages of establishing a wireless ad hoc network with unknown network density and no pre-configured network, this solution can be used to quickly complete the access of all nodes. Once the system is stable, it can be switched to regular transmission mode to transmit more data.

[0050] 3. No additional power control is required to adjust the sensing range and communication range. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of a specific implementation of the wireless channel described in this invention, which is divided into multiple time frame periods according to the time axis.

[0052] Figure 2 This is a side view of a specific embodiment of the data range described in this invention;

[0053] Figure 3 This is a schematic diagram illustrating a specific embodiment of the time slot described in this invention;

[0054] Figure 4 This is a schematic diagram of a specific embodiment of the present invention;

[0055] Figure 5 This is a schematic diagram of a specific process for step 1 of the present invention;

[0056] Figure 6 This is a schematic diagram of a specific process for step 2 of the present invention;

[0057] Figure 7 This is a schematic diagram of a specific process of the control method described in this invention. Implementation

[0058] The following is in conjunction with the appendix Figures 1 to 3 The specific embodiments of the present invention will be further described in detail below.

[0059] This invention utilizes a TDMA-based wireless network protocol to organize the wireless channel into a periodic time-frame structure, with each time frame further divided into a certain number of time slots. The protocol operates in time-frame cycles, as follows: Figure 1 As shown. A time slot, as the basic unit of radio resource management, is synonymous with a channel in the TDMA architecture, with a typical time slot length of 8ms. A node accessing a collision-free channel means that the node occupies a time slot within a time frame period, and data transmission in that time slot will not collide with other transmitting nodes.

[0060] Time synchronization is not the focus of this solution. Currently, internal synchronization algorithms are becoming mature, and the cost of external synchronization technologies such as time synchronization and high-precision clocks is gradually decreasing. Moreover, many network environments have other infrastructure available to assist in synchronization. Therefore, this solution assumes that time synchronization has been accomplished through other means, and all network nodes use synchronized time frames.

[0061] The central objective of the scheme is to ensure successful access for all nodes, defined as "each node acquiring at least one time slot within a time frame period, and data transmission within its acquired time slots proceeding without conflict." In the TDMA architecture, once a node successfully accesses a time slot, it will continuously occupy that time slot for data transmission in subsequent time frame periods. This node is called the "occupier" of that time slot, or it is said to have "acquired" that time slot. For example, if node C successfully accesses time slot 5 in the 3rd time frame period, it will continue to use time slot 5 for data transmission in subsequent time frame periods.

[0062] The solution can operate normally under various conditions, whether it's the initial network access when a large number of wireless network nodes are powered on simultaneously, or a new node connecting to a network that has been running for some time. For ease of explanation, let's define a generalized scenario: one or more indefinite numbers of nodes attempt to connect to the network simultaneously. The network includes nodes that have already been connected and running normally for some time, with a status of "connected"; and nodes that are attempting to connect, with a status of "awaiting connection".

[0063] When a node accesses a node, the time frame period includes time slots that have been accessed by other nodes and idle time slots. The node receives signaling in the time slots that the adjacent nodes have already accessed. The instruction contains a message containing network control information. In this scheme, the signaling sent by a node should include the access status of each time slot in the time frame period within the one-hop range that the node is aware of.

[0064] The node selects an available time slot to attempt access. Once the node successfully accesses a time slot, the time slot structure is the same as that of a typical data time slot, such as... Figure 2 As shown.

[0065] When a node attempts to access an idle time slot, it is divided into slots using a "contention for access" structure, such as... Figure 3 As shown, a contention access time slot consists of three intervals: a contention interval, a hidden terminal elimination interval, and a data interval. The contention interval is used to resolve contention within a single hop, and it consists of multiple contention micro-slots. A contention micro-slot is distinct from a time slot and is a smaller time slice, approximately tens of microseconds.

[0066] Each contention microslot includes the turnaround time between transmit and receive modes and the time to send a very short message, called the contention signal, denoted as CSi. It contains the identity ID of the sending node. The identity ID is a unique identifier for each node in the network and is not limited in terms of acquisition method and length. For example, it can be represented by a 48-bit MAC address.

[0067] The hidden terminal elimination interval is used to solve the hidden terminal problem and consists of multiple elimination micro-slots. Within this interval, each eliminated non-sender node sends a hidden terminal elimination message in a randomly selected elimination micro-slot. Finally, the successful bidder sends a victory message (FI) within the data interval, which includes its awareness of the status of each slot within the time frame period. For example, if it knows that one slot has been successfully occupied, it contains n data blocks. Each data block contains two fields: {SID field: indicating which slot; HCM field: a hidden terminal elimination message with its own generated mask}.

[0068] In this invention, the time frame period of the wireless scenario includes multiple time slots, which, from front to back, include a contention interval, a hidden terminal elimination interval, and a data interval; the contention interval includes k contention micro-time slots.

[0069] The control method includes a competition process for each time slot within each time frame period. The nodes participating in the competition process are all nodes within a single-hop collision domain. The competition process includes the following steps:

[0070] Step 1. Competition Phase: Step 1 takes place within the competition interval.

[0071] Step 101. For each node attempting to connect, generate a k-bit random number b = {bi}, i = (1, 2, ..., k);

[0072] Step 102. The node performs a corresponding action in the corresponding contention micro-slot based on each digit of the random number, specifically:

[0073] If bi=1, the node sends a contention signal CSi to contend for the channel;

[0074] Otherwise, if bi=0, node X listens to the channel;

[0075] During the channel monitoring process, if other nodes are detected contending for the channel, the node will relinquish the contention in that time slot and exit the competition.

[0076] Step 103. Define all nodes that have withdrawn from the contention as non-sender nodes. Each non-sender node listens to all contention signals CSi. When there is exactly one station transmitting in the j-th contention micro-slot, the non-sender node generates a mask. The mask is a k-bit string, with the j-th bit being 1 and all other bits being 0.

[0077] Step 104. Nodes that have not withdrawn from the competition proceed to Step 2 as the winning nodes;

[0078] When a node, such as X, selects an idle time slot and attempts to compete for access, it generates a k-bit random number b = {bi}, i = (1, 2, ..., k), where k is the number of contested micro-time slots in a competition interval. For each node, measures such as limiting competition to only once within a certain period can be used to mitigate competition.

[0079] The action of node X in contending for micro-slot i has two possible outcomes: if bi=1, the node sends a contention signal CSi; otherwise, node X continues to listen to the channel. If the channel is busy, i.e., it detects that one or more other nodes are transmitting on the channel, node X stops further transmission, relinquishes its contention for this slot, and becomes a non-sender node.

[0080] If no other node participates in the channel contention process in step 102, the node that is the only one to send the contention signal CSi may be the winner, but it is not necessarily the winning node.

[0081] In principle, nodes in a wireless network cannot know how many nodes are contending for the network during the network construction phase. For example, in the specific embodiment, node C only knows that it did not receive any messages during its listening time slots, such as micro-time slots 4, 5, and 7, during the entire contention phase. Therefore, it cannot determine that node C is definitely the winning node.

[0082] A single-hop collision domain is defined as a region where any two nodes are within one hop of each other. If each node in the single-hop collision domain generates a distinct random number bi, only one node will survive the contention interval and proceed to step 2 to continue transmission. If two or more nodes generate the same random number, and it is the largest among all generated numbers, a collision may occur. A sufficiently large k value can be chosen to maintain a satisfactory low collision probability, and other disaster recovery mechanisms can be designed to eliminate the impact.

[0083] Non-sender nodes are defined as nodes within a single-hop conflict domain that have successfully accessed other time slots and are no longer competing, and nodes that have not yet successfully accessed and failed to become competing receivers during the current time slot competition.

[0084] A non-sender node Y determines its recognized winner by examining the first successfully received and decoded contention signal. If multiple stations transmit signals in the same contention microslot, Y cannot receive a valid contention signal and waits for the next contention microslot. When exactly one station is transmitting in a contention microslot, say microslot i, node Y can receive a valid contention signal CSi. At this point, node Y generates a mask, which is a k-bit string where the i-th bit is 1 and all other bits are 0.

[0085] like Figure 4 The connections between nodes indicate a link. Assume nodes B, C, H, and G want to compete for a time slot within a contention interval. After the first contention micro-slot, node B gives up because it detects a transmission from node C. For the same reason, node H gives up after the third contention micro-slot. At the end of the contention phase, nodes C and G survive and are ready to proceed to step 2.

[0086] Among them, the one-hop adjacent nodes A, B, D, E, and H of C each generate a mask, which will not be written out here, but the result of ANDing them with the random code (11100101) generated by C is not 0. At the same time, among the one-hop adjacent nodes E, K, and H of G, the mask generated by K is 10000000, which is ANDed with the random code 11100100 of G and the result is 1, while the masks generated by H and E are 00000001, which are ANDed with the random code of G and the result is 0.

[0087] A typical processing flow for each node during the contention phase of an access time slot is as follows: Figure 5 As shown.

[0088] Step 2

[0089] If only one node remains in the competition after step 1, proceed directly to step 3.

[0090] Otherwise, proceed to step 201.

[0091] Step 201. All non-sender nodes send contention feedback messages to all winning nodes.

[0092] The contention feedback information includes a SID field indicating the time slot and an HCM field containing the mask generated in step 103;

[0093] Step 201.

[0094] Each winning node performs a bitwise AND operation between its k-bit random number and the mask in each HCM field. If all the results are non-zero, the contention is considered successful.

[0095] Use the successful winner node as the winner node to proceed to step 3.

[0096] After step 1, only one node can survive in a single-hop collision domain unless it generates the same random number that happens to be the largest of all generated numbers. The node that survives after step 1 is called the winner node, and there may be multiple winner nodes. However, the hidden terminal problem, unique to multi-hop wireless networks, remains unresolved. In the example above, since nodes C and G cannot receive each other's contention signals, they both believe themselves to be the winner after step 1, thus collisions may occur during data transmission intervals. However, their common neighbors H and E can identify the true winner, namely the node with the higher random number.

[0097] Taking adjacent nodes H and E as examples, the non-sending nodes handle this in two ways.

[0098] If the node status is "connected", meaning it has already acquired its own time slot, then the signaling for the next transmission of its own time slot will include a contention feedback message, which includes two fields: {SID field: indicating which time slot, HCM field: hidden terminal clearing message with its own generated mask}.

[0099] If a node is in an unaccessed state (i.e., has not yet occupied a time slot), it randomly selects a elimination micro-time slot within the hidden terminal elimination interval and sends an HCM field with its own mask in this elimination micro-time slot. Each winning node performs a bitwise AND operation on its random number with all the HCM masks received in the time slot it was contending for access in and in each time slot of the next frame period. If the result is non-zero, the contention is considered successful and the time slot has been acquired; otherwise, an idle time slot is reselected to attempt access.

[0100] In the example above, based on the mask information contained in the HCM field, node C, when ANDed with H and E, results in a non-zero AND, making it the sole winner. Node G, however, results in a zero AND, and is eliminated. The AND operation is the sum of the products of corresponding digits of two multi-digit numbers. For example, the AND operation of 1101 and 0010 results in 1*0 + 1*0 + 0*1 + 1*0 = 0.

[0101] Assuming each hidden terminal elimination interval includes m elimination micro-slots, the processing flow of a node in the hidden terminal elimination phase of a contention access slot is as follows: Figure 6 As shown.

[0102] Step 3. Data transmission phase. The winning node sends victory information FI to other nodes. The FI information contains the state information of each time slot in the time frame period that was previously known and the information of the time slot it has newly occupied. Other nodes update the state of each time slot in the time frame period according to the victory information FI.

[0103] The winning node transmits data.

[0104] If the winning node, during the contention for access slot, performs a bitwise AND operation on all the HCM masks received and its own random number, and the result is non-zero, then it sends a victory message FI during the data transmission interval of that slot. The FI contains the previously known state information of each slot within the time frame period and the information of the slot it has newly occupied. If neighboring nodes receive the victory message FI and decode it correctly, they update the state of each slot within the time frame period.

[0105] Note that the HCM field received in this time slot may not be all of them, because some connected neighbor nodes will only send HCM in the time slots they occupy. Therefore, the victory information FI sent by the node in this time slot may cause collisions.

[0106] After going through steps 1 to 3, the winning node is very likely to be the real winner. For the real winner, this data transmission phase can accelerate their access and the maintenance of information with their neighbors. Conversely, if a node mistakenly believes itself to be the winner because it does not obtain the HCM field completely, it will only cause a collision at some receiving nodes in this FI, and the HCM field transmitted by the subsequent neighboring nodes in their access time slots will also eliminate the misunderstanding.

[0107] In summary, the processing flow of a node in any time slot within a time frame period is as follows: Figure 7 As shown.

[0108] The purpose of establishing a disaster recovery mechanism is to handle abnormal situations such as terminal intrusion, channel errors, or attacks. If a node needs to re-access a time slot, it can choose to announce other time slots still occupied by itself; or it can choose an idle time slot within a recognized time frame period and, like a newly joined node, initiate the aforementioned contention process to re-attempt to occupy it. As a receiver: when node X does not receive signaling from neighboring node Y in a time slot occupied by Y (possibly due to collision decoding failure, node mobile link changes, etc.), or receives signaling from another node, and if this situation accumulates for two time frame periods, then the new state will be used to update the status information of each time slot within its own time frame period, and it will announce this in the next time slot occupied by this node.

[0109] The foregoing descriptions are preferred embodiments of the present invention. Unless there is a clear contradiction between the preferred embodiments or a prerequisite for a particular preferred embodiment, the preferred embodiments can be arbitrarily combined and used. The embodiments and specific parameters described are only for clearly illustrating the inventor's invention verification process and are not intended to limit the scope of patent protection of the present invention. The scope of patent protection of the present invention shall still be determined by its claims. Similarly, any equivalent structural changes made based on the description and drawings of the present invention shall also be included within the scope of protection of the present invention.

Claims

1. A binary countdown medium access control method for wireless scenarios, characterized in that, The time frame period of the wireless scenario includes multiple time slots, which, from front to back, include a contention interval, a hidden terminal elimination interval, and a data interval; the contention interval includes k contention micro-time slots; The control method includes a competition process for each time slot within each time frame period. The nodes participating in the competition process are all nodes within a single-hop collision domain. The competition process includes the following steps: Step 1. Performed within the competition interval. Step 101. For each node attempting to connect, generate a k-bit random number b = {bi}, i = (1, 2, ..., k); Step 102. The node performs a corresponding action in the corresponding contention micro-slot based on each digit of the random number, specifically: If bi=1, the node sends a contention signal CSi to contend for the channel; Otherwise, if bi=0, node X listens to the channel; During the channel monitoring process, if other nodes are detected contending for the channel, the node will relinquish the contention in that time slot and exit the competition. Step 103. Define all nodes that have withdrawn from the contention as non-sender nodes. Each non-sender node listens to all contention signals CSi. When there is exactly one station transmitting in the j-th contention micro-slot, the non-sender node generates a mask. The mask is a k-bit string, with the j-th bit being 1 and all other bits being 0. Step 104. Nodes that have not withdrawn from the competition proceed to Step 2 as the winning nodes; Step 2. If only one node remains in the competition after step 1, that node will be the winner and proceed directly to step 3. Otherwise, proceed to step 201; Step 201. All non-sender nodes send contention feedback messages to all winning nodes. The contention feedback message includes a SID field indicating the time slot and an HCM field containing the mask generated in step 103; Step 201. Each winning node performs a bitwise AND operation between its k-bit random number and the mask in each HCM field. If all the results are non-zero, the contention is considered successful. Use the successful winner node as the winner node to proceed to step 3; Step 3. The winning node sends the victory information FI to the other nodes. The FI information contains the state information of each time slot in the time frame period that was previously known and the information of the time slot it has newly occupied. The other nodes update the state of each time slot in the time frame period according to the victory information FI. The winning node transmits data.

2. The control method as described in claim 1, characterized in that, In step 201, the time for non-sender nodes to send contention feedback messages to all winning nodes is: If the node is the one that relinquishes the contention, then the message is sent in the hidden terminal elimination interval; If the node is the one performing node access, it will send the message in the time slot when the contention is successful.

3. The control method as described in claim 2, characterized in that, The hidden terminal elimination interval includes multiple elimination micro-time slots, and the node that relinquishes contention randomly selects one elimination micro-time slot to send.

4. The control method as described in claim 1, characterized in that, The non-sender nodes also include the winner nodes of other time slots.

5. The control method as described in claim 1, characterized in that, The contention signal CSi is the MAC address information of the node.

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