CN107222932B - Time slot access control method based on neighborhood feedback - Google Patents
Time slot access control method based on neighborhood feedback Download PDFInfo
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Abstract
The invention provides a time slot access control method based on neighborhood feedback, which comprises the following steps: s1: the MAC layer is controlled to send a downlink control frame to the physical layer, the downlink control frame comprises a receiving and sending mode control field and a local terminal feedback field, and the receiving and sending mode control field and the local terminal feedback field are respectively used for controlling the receiving and sending mode of the physical layer and feeding back the content to the neighborhood terminal; s2: and controlling the MAC layer to receive an uplink service frame sent by the physical layer, where the uplink service frame includes a neighborhood feedback field, and the neighborhood feedback field is used to indicate the content of feedback from the neighborhood terminal to the terminal, and returning to step S1. The invention utilizes the inter-terminal time slot usage table as the transmission of feedback information, improves the access speed of the network and the utilization rate of time slot resources according to reasonably acquiring and analyzing neighborhood feedback information, and can be effectively applied to the time slot allocation and access of the broadcast MANET network based on the TDMA.
Description
Technical Field
The invention relates to the technical field of communication, in particular to a time slot access control method based on neighborhood feedback.
Background
A MANET (Mobile Ad Hoc Network) refers to a Network formed by a group of nodes communicating with each other, satisfying specific requirements, and operating in a specific scene. Unlike the internet and cellular networks, the positions between MANET nodes are fairly equal. The nodes in the MANET not only have the functions of a common mobile terminal, but also support multi-hop communication forwarding among the nodes, namely the relay nodes can help to forward data packets. MANET networks are used in wireless scenarios to accommodate random movement between nodes. Different from a user terminal in a cellular network, the MANET network node does not depend on any base station or central node which is deployed in advance, the access algorithm adopts a completely distributed structure, each node executes the algorithm in a distributed mode and accesses the node quickly, the operation of the network is prevented from being influenced by the fault of a certain central node, and the access method has strong survivability. In addition to the characteristics of distribution and self-organization, the mobility among the nodes enables neighbor nodes in the MANET network to change constantly, and the nodes can freely join or leave the network, so that the intermediate nodes are required to forward and generate real-time multi-hop routing information, and the robustness of a routing protocol is enhanced.
A general communication network usually adopts a five-layer protocol stack structure of an application layer, a transport layer, a network layer, a data link layer and a physical layer. The physical layer is mainly responsible for processing actual data services, and serves as a service transmission medium to provide services for the data link layer of the upper layer. The data Link layer generally refers to a generic name of an LLC (Logical Link Control) layer and an MAC (Media Access Control) layer, where the LLC layer completes interaction and frame encapsulation of its upper routing layer, and the MAC layer is mainly responsible for interaction and Control with the physical layer, plans a transmission mode for reasonably accessing a physical channel, and checks received physical layer data, thereby really ensuring that a service flow can be correctly received and transmitted.
In an actual network, the communication between the MAC layer and the physical layer needs to implement a partial frame structure as an interactive interface. The frame structures comprise a downlink control frame CCH of a physical layer by an MAC layer, a downlink service frame PDCH which uses the physical layer to send services by the MAC layer, and an uplink service frame which is sent to the MAC layer by the physical layer.
In a general broadcast MANET network based on TDMA (Time Division Multiple access), each node communicates with neighboring nodes in a broadcast manner, and each node selects specific Time slots to access a physical channel according to an access algorithm, so as to realize the planning of Time slots among nodes and avoid collision. In each timeslot, a node may be in a transmitting or receiving state or a silent state, which requires the MAC to transmit a downlink control frame to the physical layer to control the operating state of the physical layer, so as to complete the switching of the operating mode of the physical layer. In order to complete the planning of the time slots among the nodes and the access of the network quickly, the nodes need to judge the conflict condition of the time slots of the nodes in a distributed mode according to the neighborhood feedback information, and therefore adjustment is carried out in time.
However, in the related art, a time slot access control method suitable for a TDMA-based broadcast MANET network is not available, so that the network access speed is slow, and the utilization rate of time slot resources is low.
Disclosure of Invention
The present invention is directed to solving at least one of the above problems.
Therefore, the invention aims to provide a time slot access control method based on neighborhood feedback, which utilizes a time slot usage table between terminals as the transmission of feedback information, improves the access speed of the network and the utilization rate of time slot resources according to reasonably acquiring and analyzing the neighborhood feedback information, and can be effectively applied to the time slot allocation and access of a broadcast MANET network based on TDMA.
In order to achieve the above object, an embodiment of the present invention provides a timeslot access control method based on neighborhood feedback, including the following steps: s1: the method comprises the steps that an MAC layer is controlled to send a downlink control frame to a physical layer, the downlink control frame comprises a receiving and sending mode control field and a local terminal feedback field, and the receiving and sending mode control field and the local terminal feedback field are respectively used for controlling a receiving and sending mode of the physical layer and feeding back content to a neighborhood terminal; s2: and controlling the MAC layer to receive an uplink service frame sent by the physical layer, where the uplink service frame includes a neighborhood feedback field, and the neighborhood feedback field is used to indicate the content of feedback from the neighborhood terminal to the terminal, and returning to step S1.
In addition, the slot access control method based on neighborhood feedback according to the above embodiment of the present invention may further have the following additional technical features:
in some examples, in S1, when the transceiving mode control field is a first preset value, the method is configured to instruct the physical layer to enter a receiving mode, when the transceiving mode control field is a second preset value, the method is configured to instruct the physical layer to enter a broadcast transmission mode, and when the transceiving mode control field is a third preset value, the method is configured to instruct the physical layer to enter a muting mode, wherein if a current slot is used for receiving a slot contention packet, the S1 further includes: step S1 a: setting a transceiving mode control field in a time slot control field of the downlink control frame to a first preset value, and then controlling the MAC layer to send the downlink control frame to the physical layer; if the current time slot is used for sending the time slot contention packet, the S1 further includes: step S1 b: setting a transceiving mode control field in a time slot control field of the downlink control frame to a second preset value, and then controlling the MAC layer to send the downlink control frame to the physical layer; if the current time slot does not need to use the physical layer operation, S1, further comprising: step S1 c: and setting a transceiving mode control field in a time slot control field of the downlink control frame to be a third preset value, and then controlling the MAC layer to send the downlink control frame to the physical layer.
In some examples, after S1b, further comprising: step S1b 1: and controlling the MAC layer to clear the neighbor terminal information received in the period and prepare to record the received information of a new period.
In some examples, after S1b1, further comprising: step S1b 2: and controlling the MAC layer to send a downlink service frame to the physical layer.
In some examples, in S1, the local terminal feedback field includes a neighbor terminal number and/or neighbor terminal timeslot usage information that is correctly received by the local terminal in the present period, and the local terminal reasonably carries the local terminal feedback information with the neighbor feedback information in a preset frame structure, and feeds back the correctly received information to the neighbor terminal.
In some examples, in S2, the neighborhood feedback field includes the number of the sending terminal and its timeslot feedback information for the terminal that correctly receives the timeslot contention packet, and the number of the sending terminal and the timeslot number of the uplink traffic frame are used to generate the terminal feedback information.
In some examples, in S2, when a certain timeslot or a certain terminal in the neighborhood feedback information of the uplink traffic frame is a first preset value, the method is used to indicate that a transmitting terminal correctly receives the timeslot or a timeslot competition packet of the terminal, and when a certain timeslot or a certain terminal in the neighborhood feedback information of the uplink traffic frame is a second preset value, the method is used to indicate that the transmitting terminal fails to successfully receive the timeslot or the timeslot competition packet of the terminal, where if the timeslot corresponding to the terminal is the first preset value, the method further includes S2: step S2 a: controlling the MAC layer to record that the number of the neighbor terminals in the period is increased by one, and the number of the successful neighbors in the period is increased by one, and returning to the step S1; if the timeslot feedback information corresponding to the timeslot of the terminal is the second preset value, the step S2 further includes: step S2 b: and controlling the MAC layer to record that the number of the neighbor terminals in the period is increased by one, wherein the number of the successful neighbors in the period is unchanged, and when the ratio of the successful neighbors is lower than a set threshold value, the terminal loses the use right of the time slot and competes for other time slots.
In some examples, in the S2b, the specific contention mode contending for the other timeslot is: according to the record of the feedback field of the terminal, if the use condition of a certain time slot is idle, the time slot is preferentially contended, and if no idle time slot exists, the time slot contention of the period is abandoned.
In some examples, the partial frame structure in the downlink control frame and the uplink traffic frame includes a check field, and the check field is used to check whether a frame structure field received by the MAC layer or the physical layer is correct.
In some examples, the uplink traffic frame and the downlink traffic frame further include: a frame type field for indicating the frame type of the uplink service frame; and the data field is used for carrying data transmitted by the MAC layer or received by the physical layer.
According to the time slot access control method based on neighborhood feedback, each terminal can reasonably analyze the conflict situation of the time slot of the terminal by utilizing the neighborhood feedback information, and controls the MAC layer to send the downlink control frame containing the control field to the physical layer when the time slot is initial.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a flowchart of a slot access control method based on neighborhood feedback according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a timeslot structure in a timeslot access control method based on neighborhood feedback according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a timeslot usage table in a method for timeslot access control based on neighborhood feedback according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a downlink CCH control frame in a neighbor feedback-based timeslot access control method according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a downlink PDCH traffic frame in a neighborhood feedback-based timeslot access control method according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of an uplink CCH traffic frame in the timeslot access control method based on neighborhood feedback according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of an uplink PDCH traffic frame in a neighborhood feedback-based timeslot access control method according to an embodiment of the present invention;
fig. 8 is a topological diagram of a slot access control method based on neighborhood feedback according to an embodiment of the present invention;
fig. 9 is a schematic diagram illustrating contention packet reception in a neighborhood feedback-based timeslot access control method according to an embodiment of the present invention;
fig. 10 is a diagram illustrating another timeslot usage table in a method for controlling timeslot access based on neighborhood feedback according to an embodiment of the invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The following describes a slot access control method based on neighborhood feedback according to an embodiment of the present invention with reference to the accompanying drawings.
Fig. 1 is a flowchart of a method for slot access control based on neighborhood feedback according to an embodiment of the present invention. As shown in fig. 1, the method comprises the steps of:
step S1: and controlling the MAC layer to send a downlink control frame to the physical layer, wherein the downlink control frame comprises a receiving and sending mode control field and a local terminal feedback field, and the receiving and sending mode control field and the local terminal feedback field are respectively used for controlling the receiving and sending mode of the physical layer and feeding back the content to the neighborhood terminal.
Step S2: and controlling the MAC layer to receive an uplink service frame sent by the physical layer, where the uplink service frame includes a neighborhood feedback field, and the neighborhood feedback field is used to indicate the content of feedback from the neighborhood terminal to the terminal, and returning to step S1.
In one embodiment of the present invention, in step S1, the physical layer is instructed to enter a receiving mode when the transceiving mode control field is a first preset value, the physical layer is instructed to enter a broadcast transmission mode when the transceiving mode control field is a second preset value, the physical layer is instructed to enter a silent mode when the transceiving mode control field is a third preset value, wherein,
if the current time slot is used for receiving the time slot contention packet, step S1, further includes:
step S1 a: setting a receiving and sending mode control field in a time slot control field of a downlink control frame to be a first preset value, and then controlling an MAC layer to send the downlink control frame to a physical layer
If the current time slot is used for sending the time slot contention packet, step S1, further includes:
step S1 b: setting a receiving and sending mode control field in a time slot control field of the downlink control frame as a second preset value, and then controlling an MAC layer to send the downlink control frame to a physical layer;
if the current time slot does not need to use the physical layer operation, step S1, further includes:
step S1 c: and setting a transceiving mode control field in a time slot control field of the downlink control frame to be a third preset value, and then controlling the MAC layer to send the downlink control frame to the physical layer.
Further, in an embodiment of the present invention, after step S1b, the method further includes:
step S1b 1: and controlling the MAC layer to clear the neighbor terminal information received in the period and prepare to record the received information in a new period.
Further, after step S1b1, the method further includes:
step S1b 2: and controlling the MAC layer to send a downlink service frame to the physical layer.
In step S1, in an embodiment of the present invention, the terminal feedback field includes a number of a neighboring terminal and/or timeslot usage information of the neighboring terminal that is correctly received by the terminal in the period, and the terminal reasonably carries the terminal feedback information with the neighboring feedback information in a preset frame structure (i.e., a suitable frame structure), and feeds back the correctly received information to the neighboring terminal.
In an embodiment of the present invention, in step S2, the neighborhood feedback field includes the number of the sending terminal and the timeslot feedback information of the terminal that correctly receives the timeslot contention packet, and the number of the sending terminal and the timeslot number of the received uplink service frame are used to generate the terminal feedback information.
Based on this, in one embodiment of the present invention, in step S2, when a certain time slot or a certain terminal in the neighborhood feedback information of the previous service frame is a first preset value, the time slot or the time slot contention packet of the terminal is used to indicate that the sending terminal correctly receives the time slot or the time slot contention packet of the terminal, and when a certain time slot or a certain terminal in the neighborhood feedback information of the previous service frame is a second preset value, the time slot or the time slot contention packet of the terminal is used to indicate that the sending terminal fails to successfully receive the time slot or the time slot contention packet of the terminal, wherein,
if the timeslot feedback information corresponding to the timeslot of the terminal is the first preset value, step S2 further includes:
s2 a: the MAC layer is controlled to record that the number of the neighbor terminals in the period is increased by one, the number of the successful neighbors in the period is increased by one, and the step S1 is returned;
if the timeslot feedback information corresponding to the timeslot of the terminal is the second preset value, step S2 further includes:
s2 b: the MAC layer is controlled to record that the number of the neighbor terminals in the period is increased by one, the number of the successful neighbors in the period is unchanged, and when the ratio of the successful neighbors is lower than a set threshold value (namely, the ratio of the successful neighbors is lower), the terminal loses the use right of the time slot and competes for other time slots.
Specifically, in step S2b, the specific contention mode for contending for other timeslots is: according to the record of the feedback field of the terminal, if the use condition of a certain time slot is idle, the time slot is preferentially contended, and if no idle time slot exists, the time slot contention of the period is abandoned.
In an embodiment of the present invention, the partial frame structures in the downlink control frame and the uplink traffic frame described above include a check field, and the check field is used to check whether the frame structure field received by the MAC layer or the physical layer is correct.
In an embodiment of the present invention, the uplink traffic frame and the downlink traffic frame further include: a frame type field for indicating the frame type of the uplink service frame; and the data field is used for carrying data transmitted by the MAC layer or received by the physical layer.
According to the time slot access control method based on neighborhood feedback, each terminal can reasonably analyze the conflict situation of the time slot of the terminal by utilizing the neighborhood feedback information, and controls the MAC layer to send the downlink control frame containing the control field to the physical layer when the time slot is initial.
In order to better understand the present invention, the following describes the timeslot access control method based on neighborhood feedback according to the above embodiments of the present invention in detail and specifically by way of example with reference to the accompanying drawings.
Example 1
In this embodiment, the MAC layer is responsible for the planning and dividing of the time slots, the MAC layer controls the logical functions of the transmission and reception time slots, and notifies the physical layer of the transmission and reception logic in the form of frames, and the physical layer itself does not relate to the concept of time slots.
Referring to fig. 2, each cycle includes n control slots and n data slots, in the control slot segment, the terminal is controlled by the MAC layer, and one or more slots are randomly selected to participate in contention, so as to obtain the usage right of the corresponding one or more slots in the data slot segment. In a certain time slot, if the terminal participates in the competition, the feedback of the time slot of the terminal by the neighborhood terminal is intercepted in a period taking the time slot as a starting point, the terminal judges the conflict condition generated by occupying the time slot according to the feedback information, and selects whether to abandon the competition of the time slot or not. The time slot structure is divided into a control section and a data section, in the control section, the terminal selects to send or receive a CCH time slot competition packet, and in the data section, the terminal selects to send or receive a data service packet.
In this embodiment, the format of the feedback information is shown in fig. 3. Each terminal maintains a slot usage table containing n bits in each period. The time slot using table is used for recording the using conditions of n time slots in the period. When the terminal receives and only receives a packet sent by one terminal in a certain time slot in the period, setting the corresponding bit of the time slot usage table maintained by the terminal as a first preset value to indicate the terminal to determine that the time slot in the period can correctly receive data without conflict; when the terminal does not receive or receives more than one packet sent by the terminal in a certain time slot in the period, setting the corresponding bit of the time slot usage table maintained by the terminal as a second preset value to indicate that the time slot in the period may generate conflict due to competition of a plurality of terminals.
And the time slot use table is used for recording the use condition of the time slot in the neighborhood collected by the terminal and taking the use condition of the time slot as feedback to the neighborhood. When the MAC layer of the terminal sends a downlink control frame to the physical layer and sets the physical layer to a sending mode, the MAC layer should provide the timeslot usage table to the physical layer at the same time, so that the information collected by the terminal is fed back to all terminals in the neighborhood in the form of a frame in a broadcast manner.
When the terminal receives the time slot using table of other terminals in the neighborhood, the terminal records whether the packet sent in the time slot used by the terminal can be correctly received by other terminals in the neighborhood without conflict. When a terminal currently contends for the third timeslot and receives the timeslot usage table of a neighboring terminal, for example, as shown in fig. 3, if the third bit in the timeslot usage table is the second preset value, it indicates that the received neighboring terminal does not correctly receive the contention packet of the terminal in this period. The terminal can judge whether to abandon the competition of the time slot or not according to the proportion of the neighbor terminals which can correctly receive the self competition packet.
In this embodiment, five possible transceiving states exist in each timeslot as follows:
1) for a time slot to be sent with a CCH time slot competition packet, the MAC layer issues a downlink CCH control frame to the physical layer at the initial time slot, the control frame is used for controlling the physical layer to set the state as a sending mode, and the time slot use table of the terminal is used as feedback information and broadcasted to other terminals in the neighborhood to quantify the serious collision condition of the used time slots.
2) For a time slot to receive a CCH time slot competition packet, the MAC layer issues a downlink CCH control frame to the physical layer at the initial time of the time slot, and the control frame is used for controlling the physical layer to set the state as a receiving mode. The MAC then prepares to receive the uplink CCH traffic frame of the physical layer. The physical layer analyzes the control frame structure after receiving the downlink control frame, and is controlled and adjusted to a receiving mode, and after receiving the competitive CCH packet, the physical layer immediately loads the time slot usage table and other parts into the uplink CCH service frame and transmits the uplink CCH service frame to the MAC layer.
3) For a time slot to be sent with PDCH, the MAC layer sends down a downlink PDCH service frame to the physical layer at the beginning of the time slot, and the service frame is used for indicating the physical layer to set the state as a sending mode in the current PDCH time slot. The MAC layer selects to transmit one or more downlink traffic frames to provide the physical layer with the traffic data to be transmitted.
4) For a time slot to receive PDCH, the MAC layer sends down a downlink PDCH service frame to the physical layer at the beginning of the time slot, and the service frame is used for indicating the physical layer to set the state to be a receiving mode in the current PDCH time slot. The MAC then prepares to receive the physical layer uplink PDCH traffic frames. The physical layer analyzes the service frame structure after receiving the downlink service frame, is controlled and adjusted to a receiving mode, immediately loads the data part and the like into the uplink PDCH service frame after receiving the competition PDCH packet and transmits the data part and the like to the MAC layer.
5) For a time slot without physical layer operation, the MAC layer issues a downlink control frame to the physical layer at the beginning of the time slot, the physical layer is controlled to enter a dormant state, the physical layer enters the dormant state after receiving the downlink control frame, and modulation and demodulation are not carried out until a new downlink control frame issued by the MAC is received.
The design process of the downlink interface is as follows:
the downlink interface comprises a downlink CCH control frame and a downlink PDCH service frame.
The downlink CCH control frame is issued to the physical layer by the MAC layer at the time slot initial segment of each control time slot, and is used for controlling the receiving and sending states of the physical layer and transmitting the time slot usage table to the physical layer. If the control time slot is a sending time slot, the physical layer adjusts the receiving and sending mode to sending according to the indication of the control frame, and sends the time slot using table of the terminal to the neighborhood terminal in a broad-width mode as feedback; if the time slot is received during the control time slot, the physical layer adjusts the receiving and sending mode to receiving according to the indication of the control frame, tries to receive the competitive CCH packet of the neighbor terminal, and if the demodulation is successful, immediately extracts the related frame structure therein, loads the related frame structure into the uplink CCH service frame and transmits the uplink CCH service frame to the MAC layer.
The downlink PDCH service frame is sent to the physical layer by the MAC layer in the time slot initial section of each data time slot, and is used for controlling the receiving and sending states of the physical layer and transmitting the data to be sent to the physical layer. If the data time slot is a sending time slot, the physical layer adjusts the receiving and sending mode to sending according to the indication of the service frame, the MAC layer can continue to send one or more downlink service frames and provide data services containing data to be sent by the physical layer; if the time slot is a receiving time slot, the physical layer adjusts the receiving and sending mode to receiving according to the indication of the service frame, tries to receive the competition PDCH packet of the neighbor terminal, and if the demodulation is successful, immediately extracts the related frame structure therein, loads the frame into the uplink PDCH service frame and transmits the frame to the MAC layer.
The design process of the downlink CCH control frame is as follows:
the downlink CCH control frame structure is shown in fig. 4.
The type is used for indicating that the frame belongs to a downlink CCH control frame, a downlink PDCH service frame, an uplink CCH service frame or an uplink PDCH service frame;
the receiving and sending node number is used for indicating the source terminal number, the terminal number and the destination terminal number;
the check is a check bit obtained by calculating the content such as the type, the serial number of the transmitting and receiving node and the like, and is used for checking whether the content is correctly received by a physical layer;
and the time slot use table is used for recording the use condition of the time slot in the neighborhood collected by the terminal and taking the use condition of the time slot as feedback to the neighborhood.
The receiving and sending control is used for indicating the receiving and sending state which should be set by the current time slot of the physical layer;
the check is a check bit obtained by calculating the contents of a time slot usage table, transceiving control, standby and the like, and is used for the physical layer to check whether the contents are correctly received.
The design process of the downlink PDCH service frame is as follows:
the downlink PDCH traffic frame structure is shown in fig. 5.
The type is used for indicating that the frame belongs to a downlink CCH control frame, a downlink PDCH service frame, an uplink CCH service frame or an uplink PDCH service frame;
the receiving and sending node number is used for indicating the source terminal number, the terminal number and the destination terminal number;
the check is a check bit obtained by calculating the content such as the type, the serial number of the transmitting and receiving node and the like, and is used for checking whether the content is correctly received by a physical layer;
the receiving and sending control is used for indicating the receiving and sending state which should be set by the current time slot of the physical layer;
the data part comprises service data to be transmitted by the MAC layer;
the check is a check bit obtained by calculating the contents of the transceiving control, the data part and the like, and is used for the physical layer to check whether the contents are correctly received.
The design process of the uplink interface is as follows:
the uplink interface comprises two uplink service frames, namely an uplink CCH service frame and an uplink PDCH service frame.
The uplink CCH control frame is in the initial section of each control time slot, and the MAC layer instructs the physical layer to switch to the receiving mode. And when the physical layer receives the competitive CCH packets of other terminals, the competitive CCH packets are immediately analyzed and formed, and the competitive CCH packets are used for providing information such as a time slot use table fed back by other terminals and the like for the MAC layer.
In the initial section of the time slot of each data time slot of the uplink PDCH service frame, the MAC layer instructs the physical layer to switch to a receiving mode. And when the physical layer receives the competition PDCH packet of other terminals, the physical layer immediately analyzes and forms the competition PDCH packet and is used for providing information such as data transmitted by other terminals for the MAC layer.
The design process of the uplink CCH service frame is as follows:
the uplink CCH traffic frame structure is shown in fig. 6.
The type is used for indicating that the frame belongs to a downlink CCH control frame, a downlink PDCH service frame, an uplink CCH service frame or an uplink PDCH service frame;
the receiving and sending node number is used for indicating the source terminal number, the terminal number and the destination terminal number;
the check is a check bit obtained by calculating the content such as the type, the serial number of the transmitting and receiving node and the like, and is used for checking whether the content is correctly received by a physical layer;
the time slot using table contains the time slot using condition fed back by the neighborhood terminal, and indicates the time slot condition that the neighborhood terminal correctly receives the competition packet.
The SNR is an SNR value measured in the process of receiving the competitive packet by the physical layer;
the check is a check bit obtained by calculating the contents of the slot usage table, the SNR, the reserve and the like, and is used for the physical layer to check whether the contents are received correctly.
The design process of the uplink PDCH service frame is as follows:
the uplink PDCH traffic frame structure is shown in fig. 7.
The type is used for indicating that the frame belongs to a downlink CCH control frame, a downlink PDCH service frame, an uplink CCH service frame or an uplink PDCH service frame;
the receiving and sending node number is used for indicating the source terminal number, the terminal number and the destination terminal number;
the check is a check bit obtained by calculating the content such as the type, the serial number of the transmitting and receiving node and the like, and is used for checking whether the content is correctly received by a physical layer;
the SNR is an SNR value measured in the process of receiving the competitive packet by the physical layer;
the data part comprises service data which needs to be transmitted to the neighbor terminal of the MAC layer;
the check is a check bit obtained by calculating the contents such as the SNR and the data part and the like, and is used for the physical layer to check whether the contents are received correctly.
Specifically, referring to fig. 8, a network with 4 nodes is shown, and they randomly select time slots to participate in time slot competition when the network is powered on.
Further, as shown in fig. 9 and fig. 10, a table is used for the randomly selected transmission time slot after the network is powered on in fig. 8 and the time slot of each node at the end of the period, respectively. Terminal A sends competition packet in time slot 1, terminals B and C choose to send competition packet in time slot 2, time slot 3 has no terminal competition, and terminal D sends competition packet in time slot 4. Due to the existence of the topology relationship and the collision, each terminal may not receive all the contention packets of other terminals correctly, and the receiving situation is as shown in fig. 9. In the first time slot, the terminals B and C can correctly receive the contention packet of the terminal a, in the second time slot, the terminal a cannot correctly receive the data of any terminal due to the collision between the terminals B and C, but the terminal D can correctly receive the contention packet sent by the terminal C due to the topological relation, and the terminal C can correctly receive the contention packet of the terminal D by the fourth time slot.
In the control segment time slot of the next period, each terminal needs to feed back the respective time slot usage table to the neighboring terminals. Based on the reception status of each terminal in the previous cycle, each terminal fills the slot usage table, as shown in fig. 10. When the terminal B and the terminal C having the conflict receive the feedback information of the neighborhood, the terminal B finds that no other terminal receives the terminal B, and the terminal C finds that one terminal, that is, the terminal D can receive the terminal C. According to a certain decision condition (which may adopt conditions such as the absolute number of neighbors or the proportional value of neighbors), the terminal B will probably give up the contention of the time slot before the terminal C, so that in the second period, the terminal B will control the MAC layer to send the downlink control frame in other time slots, and control the physical layer to change the sending time slot.
When the transmission time slot is changed, the terminal selects the time slot which is not used according to the recording condition of the time slot use table of the period to compete the use right, thereby reducing the possibility of generating conflict.
In summary, in this embodiment, in the timeslot access control method based on neighborhood feedback, since the conflicting terminals do not give up the timeslot usage right at the same time, and the terminal with the slightest last conflict situation is possibly left more, so as to successfully acquire the transmission timeslot, a fast timeslot access capability can be provided for the TDMA-based broadcast MANET network, that is, the network access speed is increased, and the timeslot resource utilization rate is increased.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (9)
1. A time slot access control method based on neighborhood feedback is characterized by comprising the following steps:
s1: the method comprises the steps that an MAC layer is controlled to send a downlink control frame to a physical layer, the downlink control frame comprises a transceiving mode control field and a local terminal feedback field, the transceiving mode control field and the local terminal feedback field are respectively used for controlling a transceiving mode of the physical layer and feeding back content to a neighborhood terminal, wherein when the transceiving mode control field is a first preset value, the transceiving mode control field is used for indicating the physical layer to enter a receiving mode, when the transceiving mode control field is a second preset value, the transceiving mode control field is used for indicating the physical layer to enter a broadcast sending mode, when the transceiving mode control field is a third preset value, the transceiving mode control field is used for indicating the physical layer to enter a silent mode, and the local terminal feedback field comprises a neighborhood terminal number and/or neighborhood terminal time slot using information which are correctly received by the local terminal in the period;
s2: and controlling the MAC layer to receive an uplink service frame sent by the physical layer, where the uplink service frame includes a neighborhood feedback field, and the neighborhood feedback field is used to indicate the feedback content of the neighbor terminal to the terminal, and returns to step S1, where the neighborhood feedback field includes the number of the sending terminal and the time slot feedback information of the terminal that correctly receives the time slot contention packet, and the number of the sending terminal and the number of the time slot that receives the uplink service frame are used to generate the feedback information of the terminal.
2. The neighborhood feedback-based slot access control method of claim 1, wherein in the S1, if a current slot is used for receiving a slot contention packet, the S1 further comprises:
s1 a: setting a transceiving mode control field in a time slot control field of the downlink control frame to a first preset value, and then controlling the MAC layer to send the downlink control frame to the physical layer;
if the current time slot is used for sending the time slot contention packet, the S1 further includes:
s1 b: setting a transceiving mode control field in a time slot control field of the downlink control frame to a second preset value, and then controlling the MAC layer to send the downlink control frame to the physical layer;
if the current time slot does not need to use the physical layer operation, S1, further comprising:
s1 c: and setting a transceiving mode control field in a time slot control field of the downlink control frame to be a third preset value, and then controlling the MAC layer to send the downlink control frame to the physical layer.
3. The neighborhood feedback-based timeslot access control method according to claim 2, further comprising, after said S1 b:
s1b 1: and controlling the MAC layer to clear the neighbor terminal information received in the period and prepare to record the received information of a new period.
4. The neighborhood feedback-based timeslot access control method according to claim 3, further comprising, after said S1b 1:
s1b 2: and controlling the MAC layer to send a downlink service frame to the physical layer.
5. The timeslot access control method according to claim 1, wherein in S1, the local terminal reasonably carries local terminal feedback information with the neighborhood feedback information in a preset frame structure, and feeds back correct reception information to the neighborhood terminal.
6. The neighborhood feedback-based timeslot access control method according to claim 1, wherein in said S2, when a certain timeslot or a certain terminal in the neighborhood feedback information of the uplink traffic frame is a first preset value, the method is used to indicate that the transmitting terminal has correctly received the timeslot or the timeslot competition packet of the terminal, and when a certain timeslot or a certain terminal in the neighborhood feedback information of the uplink traffic frame is a second preset value, the method is used to indicate that the transmitting terminal has failed to successfully receive the timeslot or the timeslot competition packet of the terminal, wherein,
if the timeslot feedback information corresponding to the timeslot of the terminal is the first preset value, the S2 further includes:
s2 a: controlling the MAC layer to record that the number of the neighbor terminals in the period is increased by one, and the number of the successful neighbors in the period is increased by one, and returning to the step S1;
if the timeslot feedback information corresponding to the timeslot of the terminal is the second preset value, the step S2 further includes:
s2 b: and controlling the MAC layer to record that the number of the neighbor terminals in the period is increased by one, wherein the number of the successful neighbors in the period is unchanged, and when the ratio of the successful neighbors is lower than a set threshold value, the terminal loses the use right of the time slot and competes for other time slots.
7. The neighborhood feedback-based timeslot access control method according to claim 6, wherein in said S2b, said specific contention mode competing for other timeslots is:
according to the record of the feedback field of the terminal, if the use condition of a certain time slot is idle, the time slot is preferentially contended, and if no idle time slot exists, the time slot contention of the period is abandoned.
8. The neighborhood feedback-based timeslot access control method according to claim 1 or 4, wherein a part of frame structures in the downlink control frame and the uplink traffic frame includes a check field, and the check field is used to check whether a frame structure field received by the MAC layer or the physical layer is correct.
9. The neighborhood feedback-based timeslot access control method according to claim 1 or 4, wherein said uplink traffic frame and said downlink traffic frame further comprise:
a frame type field for indicating the frame type of the uplink service frame;
and the data field is used for carrying data transmitted by the MAC layer or received by the physical layer.
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