Data transmission method and full-duplex Ad Hoc network system
阅读说明：本技术 一种数据传输方法及全双工Ad Hoc网络系统 (Data transmission method and full-duplex Ad Hoc network system ) 是由 朱宏 宋锐 王宇 张朝贤 张孝达 占国忠 于 2019-09-24 设计创作，主要内容包括：本发明涉及网络通信技术领域,提供了一种数据传输方法,所述方法应用于全双工Ad Hoc网络中的网络节点,包含：在有数据发送需求时,侦听数据信道；若所述数据信道为空闲状态,则通过控制信道发送指向目的网络节点的RTS报文,并在接收到来自所述目的网络节点的CTS报文后,通过所述数据信道发送数据；若所述数据信道为非空闲状态,则确定自身是否为暴露节点,若是,则通过控制信道发送指向目的网络节点的RTS报文,并在接收到来自所述目的网络节点的CTS报文后,通过所述数据信道发送数据；若否,则返回至所述数据信道侦听步骤,解决了现有技术中暴露节点所带来的问题。此外,本发明实施例还提供了一种全双工Ad Hoc网络系统。(The invention relates to the technical field of network communication, and provides a data transmission method, which is applied to network nodes in a full-duplex Ad Hoc network and comprises the following steps: when a data transmission demand exists, a data channel is intercepted; if the data channel is in an idle state, sending an RTS message pointing to a target network node through a control channel, and sending data through the data channel after receiving a CTS message from the target network node; if the data channel is in a non-idle state, determining whether the data channel is an exposed node, if so, sending an RTS message pointing to a target network node through a control channel, and sending data through the data channel after receiving a CTS message from the target network node; if not, returning to the data channel interception step, and solving the problem brought by node exposure in the prior art. In addition, the embodiment of the invention also provides a full-duplex Ad Hoc network system.)
1. A data transmission method, applied to a network node in a full-duplex Ad Hoc network, comprising:
when a data transmission demand exists, a data channel is intercepted;
if the data channel is in an idle state, sending an RTS message pointing to a target network node through a control channel, and sending data through the data channel after receiving a CTS message from the target network node;
if the data channel is in a non-idle state, determining whether the data channel is an exposed node, if so, sending an RTS message pointing to a target network node through a control channel, and sending data through the data channel after receiving a CTS message from the target network node; if not, returning to the data channel monitoring step.
2. The method of claim 1, further comprising:
and after the data transmission is finished, confirming whether ACK sent by the target network node through the data channel is received, if so, finishing the data transmission, and if not, returning to the step of monitoring the data channel.
3. The method of claim 1, wherein the method of determining whether itself is an exposed node comprises:
inquiring a local record based on the information of the destination network node;
and if the information of the destination network node is stored in the local record, determining that the local record is the exposed node.
4. The method of claim 3, wherein the method of generating the local record comprises:
and judging whether the RTS message is an exposed node or not based on the received RTS message, and recording.
5. The method according to claim 4, wherein the determining whether or not the RTS packet itself is an exposed node based on the received RTS packet specifically comprises:
after receiving an RTS message through the control channel, determining a destination address of the RTS message;
if the destination address points to other network nodes, determining whether CTS messages from other network nodes are received or not after waiting for a time slot;
if the fact that the CTS message is received is determined, determining that the CTS message is a non-exposed node;
if the CTS message is not received, determining that the CTS message is an exposed node of the network node sending the RTS message, and locally recording the information of the network node sending the RTS message.
6. The method of claim 1, wherein the method comprises:
monitoring the control channel;
when receiving an RTS message through the control channel, determining whether a destination address of the RTS message points to the destination address;
if yes, sending a CTS message to the source address of the RTS message under the condition of determining that the data can be received currently, monitoring the data channel, receiving the data sent by the source address, and replying an ACK message under the condition of correct decoding.
7. The method of claim 1, wherein the control channel and the data channel are distinguished based on direct sequence spreading for the full duplex Ad Hoc network.
8. The method of claim 7, wherein N spreading codes are obtained by direct sequence spreading for the full duplex Ad Hoc network, one of the spreading codes is selected as the control channel, and the remaining N-1 spreading codes are selected as the data channel.
9. A full-duplex Ad Hoc network system, comprising a plurality of network nodes accessing the full-duplex Ad Hoc network, the network nodes communicating with other network nodes based on the data transmission method according to any one of claims 1 to 8.
Technical Field
The present invention relates to the field of network communication technologies, and in particular, to a data transmission method and a full-duplex Ad Hoc network system.
Background
With the breakthrough of new technology and the increase of market demand, wireless communication is rapidly developed, and Ad Hoc networks (Ad Hoc) are rapidly developed. The self-organizing network can utilize the routing forwarding function of the mobile terminal, and can carry out communication under the condition of no ground infrastructure, and compared with the communication of a static satellite, the self-organizing network has the specific advantages of large coverage area, small transmission loss, short transmission delay, low cost, convenient networking mode and the like.
Each node of the self-organizing network can realize the routing function, and the routing to another node can be searched and maintained in the network, so that the self-organizing network can be widely applied to the fields of mobile conferences, mobile networks, military communication, emergency services, disaster recovery and the like.
The traditional Ad Hoc network adopts a half-duplex communication technology, one node cannot receive when transmitting and cannot transmit when receiving, and the data transmission efficiency and the frequency spectrum utilization rate are low.
In recent years, Full-Duplex (Full-Duplex) communication technology has attracted much attention in the industry with its efficient spectrum utilization and its link capacity multiplication, but in Full-Duplex communication technology, a node's transmission signal causes great interference to a node's reception signal, and this interference is called self-interference, and the development of Full-Duplex communication is greatly hindered by the presence of self-interference.
With the development of Self-Interference technology (Self-Interference Cancellation), Self-Interference is suppressed to an acceptable degree, full-duplex communication becomes possible, and theoretically, the maximum throughput rate can be increased to 2 times of half-duplex by applying the full-duplex technology to the Ad Hoc network.
However, both full-duplex Ad Hoc and half-duplex Ad Hoc have hidden node and exposed node problems. Specifically, since the Ad Hoc network has a dynamically changing network topology structure and operates in an infinite environment, and an asynchronous communication technology is adopted, each node shares the same communication channel, which has the problems of channel allocation and contention, in order to improve the channel utilization rate, the frequency and the transmission power of a mobile node are both low, and meanwhile, signals are affected by noise, channel fading and obstacles in a wireless channel, the communication distance in the mobile node is limited, and a signal transmitted by one node cannot be received by other nodes in the network, so that the problems of "hidden nodes" and "exposed nodes" exist.
Disclosure of Invention
To solve the above problem of exposing nodes, an embodiment of the present invention provides a data transmission method, where the method is applied to a network node in a full-duplex Ad Hoc network, and includes: when a data transmission demand exists, a data channel is intercepted; if the data channel is in an idle state, sending an RTS message pointing to a target network node through a control channel, and sending data through the data channel after receiving a CTS message from the target network node; if the data channel is in a non-idle state, determining whether the data channel is an exposed node, if so, sending an RTS message pointing to a target network node through a control channel, and sending data through the data channel after receiving a CTS message from the target network node; if not, returning to the data channel monitoring step.
In one implementation, the method further comprises: and after the data transmission is finished, confirming whether ACK sent by the target network node through the data channel is received, if so, finishing the data transmission, and if not, returning to the step of monitoring the data channel.
In an implementation, the method of determining whether itself is an exposed node may include: inquiring a local record based on the information of the destination network node; and if the information of the destination network node is stored in the local record, determining that the local record is the exposed node.
In one implementation, the method for generating the local record includes: and judging whether the RTS message is an exposed node or not based on the received RTS message, and recording.
In one implementation, the determining whether the RTS packet is an exposed node based on the received RTS packet specifically includes:
after receiving an RTS message through the control channel, determining a destination address of the RTS message;
if the destination address points to other network nodes, determining whether CTS messages from other network nodes are received or not after waiting for a time slot;
if the fact that the CTS message is received is determined, determining that the CTS message is a non-exposed node;
if the CTS message is not received, determining that the CTS message is an exposed node of the network node sending the RTS message, and locally recording the information of the network node sending the RTS message.
In one implementation, the method includes: monitoring the control channel; when receiving an RTS message through the control channel, determining whether a destination address of the RTS message points to the destination address; if yes, sending a CTS message to the source address of the RTS message under the condition of determining that the data can be received currently, monitoring the data channel, receiving the data sent by the source address, and replying an ACK message under the condition of correct decoding.
In one implementation, the control channel and the data channel are obtained based on direct sequence spread spectrum and then differentiated on the full-duplex Ad Hoc network.
In one implementation, after performing direct sequence spreading on the full-duplex Ad Hoc network, N spreading codes are obtained, one spreading code is selected as the control channel, and the remaining N-1 spreading codes are used as the data channel.
In addition, the invention also provides a full-duplex Ad Hoc network system, which comprises a plurality of network nodes accessed into the full-duplex Ad Hoc network, and the network nodes communicate with other network nodes based on the data transmission method.
Based on the data transmission method and the full-duplex Ad Hoc network system provided by the embodiment of the invention, the problem of node exposure in the prior art can be solved, and the problem of communication efficiency in the full-duplex Ad Hoc network can be solved, so that all nodes have full-duplex transceiving capacity, and asymmetric information transmission can be completed without sending busy tone information.
Drawings
One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the figures in which like reference numerals refer to similar elements and which are not to scale unless otherwise specified.
Fig. 1 is a flow chart illustrating a data transmission method according to a first embodiment of the invention;
FIG. 2 is a schematic diagram of a data transmission process according to a first embodiment of the invention;
FIG. 3 is a schematic diagram of another data transmission process according to another embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating a method for determining local record generation according to a first embodiment of the present invention;
FIG. 5 shows a data transmission method according to a second embodiment of the present invention;
fig. 6 is a schematic diagram illustrating a full-duplex Ad Hoc network system according to a third embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, it will be appreciated by those of ordinary skill in the art that numerous technical details are set forth in order to provide a better understanding of the present application in various embodiments of the present invention. However, the technical solution claimed in the present application can be implemented without these technical details and various changes and modifications based on the following embodiments.
A first embodiment of the present invention provides a data transmission method, which is applied to a network node in a full-duplex Ad Hoc network. Refer to fig. 1.
Fig. 1 is a flowchart illustrating a data transmission method according to a first embodiment of the invention. As shown in fig. 1, the method specifically includes the steps of:
The full-duplex Ad Hoc network of the embodiment of the invention can carry out communication based on a Direct sequence spread Spectrum (Direct sequence spread Spectrum) transmission mode, the Direct sequence spread Spectrum can utilize a high-speed spread Spectrum sequence to spread the Spectrum of a signal at a transmitting end, and the same spread Spectrum code sequence is used for de-spreading at a receiving end, so that the spread Spectrum signal is restored into the original signal.
For example, the frequency spectrum of the signal may be spread to N spreading codes at the transmitting end, one of the spreading codes may be used as a control channel, and the remaining N-1 spreading codes may be used as a data channel, where the control channel may be used to transmit an RTS/CTS message and an ACK (acknowledgement character) message, and the data channel is used to transmit traffic data. By utilizing the orthogonality of the spreading codes, the control channel and the data channel can not interfere with each other, so that the network node can independently judge the data transmission request of other nodes by utilizing RTS/CTS information.
The Ad Hoc network is a wireless network, wherein network nodes can monitor communication channels based on csma (carrier sense multiple access), i.e., carrier sense multiple access technology, and determine whether data channels are idle.
And 102, judging whether the data channel is idle, if so, entering a
Fig. 2 is a schematic diagram of a process of sending data between network nodes, where fig. 2 is a schematic diagram of a data transmission process according to a first embodiment of the present invention.
As shown in fig. 2, the spreading sequence for the control channel is S0, the spreading sequence for the data channel is S1-SN-1, and when the network node N1 needs to send traffic data to the network node N2, and when the network node N1 detects that the data channel is idle S1-SN-1, the control channel with the spreading sequence S0 may first send an RTS message to the network node N2 to request communication.
After receiving the RTS message from N1, N2 replies to N1 with a CTS message via the control channel with spreading sequence S0.
After waiting for the time slot SIFS, after receiving the CTS message sent by N2, N1 sends the service data to N2 through the data channel with the sequence of S1-Sn-1.
N2 replies to the ACK message after completing the service data reception.
It should be noted that after the data transmission is completed, N1 needs to confirm whether the ACK sent by N2 is received, if so, it confirms that the data transmission is completed, and if not, it returns to the step of monitoring the data channel and prepares for retransmission.
It should be noted that, in the embodiment of the present invention, when receiving the RTS message from N1, N2 may simultaneously determine whether there is service data to be sent to N1, if there is a service data to be sent to N1, after replying to the CTS message, the N2 may directly send the RTS message to N1 through the control channel, and correspondingly, after receiving the RTS message from N2, the N1 may directly reply to the CTS message, thereby completing the handshake between N2 and N1, and the N2 may send the service data to N1 through the data channel, thereby implementing full duplex communication. Referring to fig. 3, fig. 3 is a schematic diagram illustrating another data transmission process according to another embodiment of the invention.
And 104, determining whether the node is an exposed node, if so, entering a
When the network node has data to be sent, the data channel is intercepted, and when the data channel is determined to be non-idle, the local record can be further inquired to judge whether the network node is the exposed node of the target network node. The local record stores information of other network nodes, specifically node identification information or address information and other information that can be used for uniquely determining the node identity.
The method for generating the local record comprises the following steps: and judging whether the RTS message is an exposed node or not based on the received RTS message, and recording.
Referring to fig. 4, fig. 4 is a schematic diagram illustrating a method for generating a deterministic local record according to a first embodiment of the invention.
As shown in fig. 4, the method for generating the local record may include the following steps:
If the destination address of the RTS message that the network node can receive is not itself, it can be determined that other network nodes in its communication range are requesting to send data, in this case, the received message information can be continuously judged, if a CTS message from other network nodes to which the destination address points can be received, it indicates that the destination network node is also in its communication range, and if it cannot be received, it can indicate that itself is an exposed node of the RTS message sending end.
and 242, if the CTS message is not received, determining that the node is an exposed node, and recording.
Specifically, the recorded information may include information of the network node sending the RTS packet, such as address information, identity, and the like, and is stored in a local record, so that a local record may be generated.
It should be noted that due to the dynamic nature of the Ad Hoc network, the network structure may change with the addition or deletion of nodes, and the relationship between network nodes may change accordingly. In this way, by setting a record validity time limit within which it can be determined that the network node itself is an exposed node with respect to the record, if the validity time limit is exceeded, the record can be updated, and the updating method includes direct deletion or re-determination.
In a specific implementation, when receiving an RTS message whose destination address does not point to itself, a network node may determine to expose a node, update a local record in real time, and synchronously record an effective time limit, where the effective time limit may be the sum of the current system time and a preset time, and the preset time limit may be set based on the active state of the network.
After the local record is generated by the method, when the network node has data to send, the information of the destination network node, such as a destination address, may be determined first, and the local record may be queried based on the information of the destination network node, and if the information of the destination network node is stored in the local record, the local record may be determined to be an exposed node.
The foregoing embodiments are mainly described in terms of a sender in a data transmission method, and in order to more clearly describe a data transmission method provided in an embodiment of the present invention, a receiver of data transmission will be described based on an embodiment shown in fig. 5.
Referring to fig. 5, fig. 5 shows a data transmission method according to a second embodiment of the invention. The application scenario of the present embodiment is the same as that of the above embodiment.
The data transmission method provided by the embodiment specifically includes the following steps:
Specifically, the network node may monitor the control channel in real time and identify the received packet.
It should be noted that, in this step, if the network node determines that it is not idle at present and cannot receive data, it is not necessary to reply to the CTS packet; if the decoding is incorrect, the visible transmission data is invalid and the ACK message is not replied.
Based on the same inventive concept, the invention also provides a full-duplex Ad Hoc network system.
Referring to fig. 6, fig. 6 is a schematic structural diagram of a full-duplex Ad Hoc network system according to a third embodiment of the present invention.
As shown in the figure, the system includes a plurality of network nodes (
Therefore, the data transmission method and the full-duplex Ad Hoc network system provided by the embodiment of the invention can realize the following beneficial effects:
1. by adopting a direct sequence spread spectrum mode, a control channel and a data channel of a full-duplex Ad Hoc network are separated, and the orthogonalization of an RTS/CTS and the data channel is realized, so that a network node can simultaneously send or receive control information when receiving and sending data;
2. the problem of communication efficiency in a full-duplex Ad Hoc network is solved, all nodes have full-duplex transceiving capacity, and asymmetric information transmission can be completed without sending busy tone information;
3. the problems of hidden nodes and exposed nodes of the Ad Hoc network are solved, and the performance of the full-duplex network is further exerted.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
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