CN102611523A - System and method for single-channel serial wireless multi-hop link rapid transmission - Google Patents

Abstract

The invention belongs to the technical field of communication, in particular to a single-channel serial wireless multi-hop link fast transmission system and method. The single-channel serial wireless multi-hop link fast transmission method of the present invention, it follows the steps: ①The source node sends data to the next hop node in the direction of the destination node; ②The intermediate node receives the data of the previous hop node, and performs error checking , if an error occurs, the node does nothing, the previous hop node waits for the set time and fails to detect the data forwarded by the intermediate receiving node, then resends the data, and returns to the initial state of this step; if no error occurs, judge Whether the node is the destination node, if not, forward the data to the next hop node, and then return to the initial state of this step; if so, the destination node sends an ACK to the previous hop node, and the entire transmission process ends. The invention solves the technical problem of fast data transmission on a single-channel serial wireless multi-hop link.

Description

Single-channel serial wireless multi-hop link fast transmission system and method

technical field

The invention belongs to the technical field of communication, in particular to a single-channel serial wireless multi-hop link fast transmission system and method.

Background technique

In order to effectively guarantee QoS in a wireless multi-hop network, two problems need to be solved: one is how to realize channel resource reservation, and the other is how to realize fast data transmission in the reserved channel.

The main reason why traditional resource reservation methods are difficult to use in wireless multi-hop networks is that in order to prevent data transmission in the reserved path from being damaged by the interference of surrounding nodes, the data transmission of adjacent nodes is suppressed, resulting in low network efficiency. Resource reservation methods proposed in recent years usually require strict network synchronization, which is difficult to achieve for larger-scale wireless multi-hop networks.

Wireless mesh network (also known as wireless Mesh network) is a network characterized by wireless multi-hop relay that combines mobile Ad hoc network and infrastructure network structure. The difference in service mode is the biggest difference between the wireless mesh network and the mobile Ad hoc network. The mobile Ad hoc network bears the service flow between any pair of nodes, while the wireless mesh network mainly carries the business to and from the Internet gateway. Carry business flow between any pair of nodes.

Yan Junrong et al. proposed a wireless link interference analysis model at the data link layer according to the characteristics of wireless mesh network traffic presenting a tree-like topology aggregation, and transformed omnidirectional wireless interference into wireless link interference with specific directions. According to the different consequences of interference on different links, the interference is classified into vertical interference between up and down hops of the same service flow and horizontal interference between parallel hops of different service flows. At the same time, OPNET simulation is used to verify that vertical interference has a much greater impact on network performance than horizontal interference, and vertical interference is the most serious interference in wireless mesh networks. On this basis, the topology of the wireless mesh network is segmented by taking the single hop in the wireless multi-hop link as the minimum segmentation unit. Therefore, the path requiring resource reservation in the wireless mesh network is a curve segment that traverses the topology subgraph hop by hop along its longitudinal interference direction. Thus, the problem of channel resource reservation can be transformed into a problem of how to temporarily allocate channels for this curve segment.

In order to eliminate the impact of channel resource reservation on surrounding nodes, the simplest method is to assign channels different from those in the topology subgraph to this path. In order to save channels, all links in the paths that require resource reservation can only be allocated one channel, thus forming a single-channel serial wireless multi-hop link, as shown in Figure 1 . Therefore, there is a need for a fast data transmission method in a single-channel serial wireless multi-hop link.

Contents of the invention

In order to solve how to quickly transmit data on a single-channel serial wireless multi-hop link, the invention discloses a single-channel serial wireless multi-hop link fast transmission system and method.

The present invention adopts the following technical solutions: a single-channel serial wireless multi-hop link fast transmission system, including a fast transmission module, an error detection and retransmission module, and a continuous interval transmission module;

Data fast transmission module: control the source node to send data to the next hop node in the direction of the destination node; when an intermediate node (not the destination node) correctly receives the data sent by the previous hop node, it does not send a confirmation frame to the previous hop node ACK, directly send the data to the next hop node;

Error detection and retransmission module: After the node receives the data sent by the previous hop node, it performs error checking (such as CRC): if there is no error, it will directly send the data to the next hop node; if there is an error, then The node discards the data, and the previous hop node cannot listen to the data forwarded by the node to the next hop node within the specified time, then it can be judged that the data sent just now has an error, so the data is retransmitted to the node;

Continuous interval transmission module: it is used to ensure that the two sending nodes before and after are able to carry out continuous transmission when the effective transmission distance Rt is 3 times apart.

The single-channel serial wireless multi-hop link fast transmission method of the present invention, it follows the steps:

①The source node sends data to the next hop node in the direction of the destination node;

②The intermediate node receives the data of the previous hop node and performs error checking (such as CRC). If an error occurs, the previous hop node waits for the set time and fails to detect the data forwarded by the intermediate receiving node, then resends the data and returns to The initial state of this step; if there is no error, judge whether the node is the destination node, if not, forward the data to the next hop node, and then return to the initial state of this step; if so, the destination node jumps up The node sends an ACK and the transmission ends.

Preferably, the two sending nodes before and after use three times the effective transmission distance Rt to perform continuous transmission.

The invention solves the technical problem of fast data transmission on a single-channel serial wireless multi-hop link.

Description of drawings

Figure 1 Schematic diagram of a single-channel serial wireless multi-hop link.

Fig. 2 is a schematic diagram of fast transmission of data without errors.

Figure 3 is a diagram of the implicit confirmation mechanism.

FIG. 4 is a schematic diagram of data retransmission with errors.

Fig. 5 is a flowchart of fast data transmission on a single-channel serial wireless multi-hop link.

Figure 6 is a system block diagram.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

Firstly, the single-channel serial wireless multi-hop link fast transmission method of the present invention will be described in detail in conjunction with the accompanying drawings.

In a single-channel serial wireless multi-hop link, the transmission of data is from the source node through each intermediate node in turn, and finally reaches the destination node. Therefore, it is not necessary to adopt the method of competing for access.

In order to realize fast data transmission, a transmission strategy in which the intermediate node omits the step of sending ACK (Acknowledge) messages is adopted. As shown in Figure 2 and Figure 3, when node B correctly receives the DATA1 sent by node A, it sends the DATA1 message to node C instead of sending an ACK message to node A. At this time, using the characteristics of open transmission of signals in wireless media, when node B sends DATA1 to node C (the solid line in Figure 3), node A can also monitor the DATA1 sent by node B to node C (in Figure 3 dashed line), which can be equivalent to node A receiving the ACK message from node B.

After Node B receives the data sent by its Node A, it first performs error checking (for example, cyclic redundancy check CRC). If no error occurs, the data is sent to node C directly. If an error occurs, node B discards the data, and at this time, the data will not be forwarded to node C, nor will any error notification information be sent to node A. If node A fails to listen to the data forwarded from node B to node C within the specified time, it can determine that there is an error in the data sent just now, and then retransmits the data to node A and node B.

In order to improve the data transmission efficiency, a continuous transmission strategy with a distance interval of 3 times the effective transmission distance Rt is adopted. As shown in Figure 2 and Figure 3, when node C sends data to node D, source node S can also send data to node A, but it must be ensured that the distance between the two sending nodes is at least 3 times Rt. At this time, although node A is within the interference range of node C, node A's transmission of data is suppressed, but node A's reception of data is not suppressed. Node A can simultaneously detect the strong signal of source node S and the weak signal of node C. According to the "capture effect", node A can still accurately receive the data sent by source node S. In addition, the continuous transmission of 3 times the Rt distance interval is also easy to realize. When the node S cannot hear the signal sent by the downstream node, it indicates that the interval reaches 3 times the Rt distance.

The above implementation process can be represented by a flow chart (Fig. 5).

Referring to Fig. 6, the single-channel serial wireless multi-hop link fast transmission system of the present invention includes:

(1) Fast data transmission module: use the characteristics of single-channel serial wireless multi-hop links to simplify the basic access method (DATA+ACK) and RTS/CTS method (RTS+CTS+DATA+ACK) in the wireless network . As shown in Figure 2, when a node correctly receives the data sent by the previous hop node, it does not need to send an acknowledgment frame ACK to the previous hop node, but directly sends the data to the next hop node. At this time, the openness of wireless transmission is used, because while sending data to its next-hop node, its previous-hop node can also monitor the data. That is to say, the function of ACK is implied, as shown in FIG. 3 .

(2) Error detection and retransmission module: after the node receives the data sent by its previous hop node, it first performs error checking. If there is no error, the data is directly sent to the next hop node. If an error occurs, the node will discard the data, and will not forward the data to the next hop node, nor will it send any error notification information to the next hop node. If the previous hop node cannot monitor the data forwarded by the node to the next hop node within the specified time, it can be determined that there is an error in the data sent just now, so the data is retransmitted to the node, as shown in Figure 4.

(3) Continuous interval transmission module: it improves the utilization rate of the reserved channel. In order to improve data transmission efficiency, a continuous transmission strategy of 3 times the Rt distance interval is adopted. As shown in Figure 2 and Figure 3, according to the "capture effect", as long as the two sending nodes are separated by 3 times the effective transmission distance Rt, effective data transmission can still be performed between the two pairs of nodes.

Of course, those of ordinary skill in the art should recognize that the above embodiments are only used to illustrate the present invention, rather than as a limitation to the present invention, as long as they are within the scope of the present invention, changes and modifications to the above embodiments are all Will fall within the protection scope of the present invention.

Claims (3)

1. A single-channel serial wireless multi-hop link fast transmission system, characterized by including a fast transmission module, an error detection and retransmission module, and a continuous interval transmission module; Data fast transmission module: control the source node to send data to the next hop node in the direction of the destination node; when an intermediate node correctly receives the data sent by the previous hop node, it does not send a confirmation frame to the previous hop node, and directly sends the data to the next hop node; Error detection and retransmission module: After the node receives the data sent by the previous hop node, it performs error checking: if there is no error, it will directly send the data to the next hop node; if there is an error, the node will send the data Discard, if the previous hop node cannot listen to the data forwarded by the node to the next hop node within the specified time, it can be determined that the data sent just now has an error, so retransmit the data to the node; Continuous interval transmission module: ensure that the two sending nodes before and after are separated by 3 times the effective transmission distance for continuous transmission. 2. the single-channel serial wireless multi-hop link fast transmission method is characterized in that the steps are as follows: ①The source node sends data to the next hop node in the direction of the destination node; ②The intermediate node receives the data of the previous hop node and performs error check. If an error occurs, the previous hop node waits for the set time and fails to detect the data forwarded by the intermediate receiving node, then resends the data and returns to the beginning of this step state; if there is no error, then judge whether the node is the destination node, if not, then forward the data to its next hop node, and then return to the initial state of this step; if so, the transmission ends. 3. The single-channel serial wireless multi-hop link fast transmission method as claimed in claim 2, characterized in that: the two sending nodes before and after adopt 3 times the effective transmission distance for continuous transmission.

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