WO2010034151A1

WO2010034151A1 - Method and system for resisting interference and enlarging network capability in wireless multi-hop networks

Info

Publication number: WO2010034151A1
Application number: PCT/CN2008/072507
Authority: WO
Inventors: 郑虹; 吕辉; 戴汉庆
Original assignee: 智格网信息科技(成都)有限公司; 智格网信息科技(上海)有限公司
Priority date: 2008-09-25
Filing date: 2008-09-25
Publication date: 2010-04-01
Also published as: CN101828419A

Abstract

The invention is concerned with a method and system for reducing communication interference in wireless networks. The method of the invention includes: detecting multiple neighbor nodes of a center node; sending a first communication signal to the multiple neighbor nodes and the first communication signal is only transmitted to the nodes which are regarded as the neighbors by the center node; when the data is transferred between the center node and one of the neighbor nodes, the others of the neighbor nodes will not transmit any data in the same channel according to the first communication signal so that the communication interference in the wireless network would be reduced.

Description

Method and system for anti-interference expansion network capacity of wireless multi-hop network

The present invention relates to a wireless communication method and system, and more particularly to a method and system for wireless multi-hop network anti-interference expansion network capacity, and belongs to the field of wireless communication technologies.

Background technique

Unlike a one-hop shared network, the wireless channel of a multi-hop network is a shared broadcast channel. In a multi-hop network, when a node sends a packet, only the nodes within its coverage (called neighbor nodes) can receive it, while the nodes outside the coverage do not perceive any communication. This is precisely the advantage of a multi-hop network, that is, nodes outside the coverage of the sending node are not affected by the sending node, but can send packets at the same time.

In the prior art, the direct impact of the multi-hop shared broadcast channel is that the packet collision is related to the location of the node. In a one-hop shared broadcast channel, a packet collision is a global event. If all nodes receive the correct grouping, they are aware of the packet conflict. However, the multi-hop network adopts CSMA/CA (Carrier Sense Multiple Access/Collision Detection Method). The packet collision is only a local event, that is, other nodes in the packet network sent by one node may not be received, and thus a "hidden node" may appear. "problem.

As shown in Fig. 1, when node C issues packet information, since node A is not within the antenna coverage of node C, node A becomes a "hidden node" that cannot receive packet information.

It is known that a method for solving a "hidden node" is to use a transmitting node to perform a short control message handshake with a receiving node before transmitting data, for example, requesting transmission and allowing transmission of a signal (RTS/CTS, Request to The transmission of Send/Clear to Send is one of the methods for implementing a short control message handshake.

However, the introduction of the request to send/allow the transmission will have an impact on the network capacity of the entire system. If the transmit power of the CTS (Clear to Send) is too large, some unrelated nodes will be notified by mistake, causing unnecessary "waiting" of the unrelated nodes, which reduces the network capacity of the entire system. But another On the other hand, if the transmission power of the CTS (Clear to Send) is too small, the function of notifying other neighboring nodes is not achieved. Packets collide with each other, which also leads to a reduction in the network capacity of the entire system. Therefore, this technique requires finding a reasonable balance between the transmit power of the communication signal (for example, allowing the signal to be transmitted) and the network capacity.

Summary of the invention

It is an object of the present invention to overcome the deficiencies in the prior art and to provide an effective solution that can greatly improve the network capacity of the entire network. The method and system of the present invention can utilize a parameter that regulates the transmission of the communication signal to reduce interference and increase network capacity.

In an embodiment of the present invention, a transmitting node (also referred to as a node) sends a communication signal to a receiving node (also referred to as a central node) before sending data, for example, sending The node (ie, the node) may first perform a short control message handshake with the receiving node (ie, the central node), and notify the neighboring node that it is about to receive the short message, and the communication signal may be, for example,

RTS/CTS method (Request to Send/Clear to Send).

According to the present invention, a transmission rate and a transmission power of a CTS (Clear to Send) signal sent by a central node can be effectively selected and controlled, so that the entire network can effectively eliminate the neighbor nodes. Interference can also greatly increase the capacity of the entire network system, so that the throughput and anti-interference of the wireless multi-hop network are greatly improved.

Thereby, the present invention can utilize the transmission of a communication signal to reduce the interference that may be generated by other neighboring nodes, and prevent the neighboring other nodes from transmitting the data packet on the same channel during the period in which the transmitting node and the receiving node transmit the data packet. , thereby reducing the occurrence of interference collisions.

The invention relates to a parameter for transmitting a communication signal, for example, a transmission rate and a transmission power of a CTS (Clear to Send) signal, using an effective mechanism for selecting and controlling, thereby achieving reduction around interference and expanding the network. Details of the contents are detailed below.

DRAWINGS

Figure 1 is an example of the antenna coverage of each node.

Figure 2 is an illustration of the correct range and interference range of the present invention. 3 is an illustration of the transmission of a packet signal in an embodiment of the present invention.

4 is an example of transmission of a communication signal in an embodiment of the present invention.

detailed description

According to the present invention, the reduction of interference and the expansion of the network capacity can be achieved by regulating the transmission of a communication signal. As shown in FIG. 4, in an embodiment of the present invention, node A (ie, a transmitting node or a local node) needs to communicate with node 0 (ie, a receiving node or a central node), and node A may send, for example, a sounding channel. A communication signal, such as a request to send (RTS) signal, if node 0 has a free channel, node 0 sends a corresponding communication signal on the sounding channel, such as a CTS (Clear to Send) signal. To inform node A that data transmission is possible. In a preferred embodiment, node 0 (ie, the central node) can simultaneously notify neighboring neighboring nodes B, C, and D (ie, neighbor nodes), and do not send on the same channel during node A and node 0 data transmission. Data to avoid collisions.

In an embodiment of the invention, a parameter for transmitting the communication signal may be a transmission rate. As shown in FIG. 2, the transmission range of the communication signal may include a correct acceptance range and an interference range. In an embodiment, the correct acceptance range may be defined as a signal-to-noise ratio (SNR) that is greater than a limit required for correct demodulation, and an interference range may be defined as a signal that is greater than noise but less than that required for proper demodulation. Limit.

According to the present invention, the transmission rate of a communication signal (e.g., allowing a transmission signal) is increased under the premise that the interference range is minimized, that is, the throughput of a single hop can be increased. This is because the rate is increased and the transmission time is short, so the network utilization is increased in one unit time. However, when the rate is high, the signal-to-noise ratio (SNR) is also increased. Therefore, to achieve the same transmission range, the transmission power is also increased, which in turn causes the interference range to become larger.

For example, in a dense small wireless network, all nodes can be seen in the same transmission range. Therefore, in the case of high rate, the large interference range generated has little effect on it. Therefore, it is dense. The small wireless network is suitable for increasing the transmission rate to increase the local network capacity. As another example, in a large wireless network, all nodes are not in the same transmission range. Therefore, in the case of a high rate, a large interference range is greatly affected, and the transmission rate of the communication signal is lowered, which can be reduced. Overall interference. Therefore, large wireless networks are suitable for lowering the transmission rate to increase the system throughput of the entire wireless network.

According to the present invention, reducing interference and enlarging the network capacity can utilize a parameter implementation of transmitting a control communication signal. In another embodiment of the invention, a parameter for transmitting the communication signal can be a transmission power. The key to the regulation of the transmission power of the communication signal is to balance the interference collision and the system network capacity. When the transmission power is too large, the communication signal will falsely notify some unrelated nodes, so that during the time period when the node sends the data packet, other nodes stop transmitting data packets because of avoiding interference collision, which in turn causes unnecessary nodes to appear unnecessary. Waiting for ", and thus reducing the network capacity of the entire system.

On the other hand, when the transmission power is too small, the communication signal does not reach the role of the neighboring nodes, and the data packets collide with each other, which also leads to a reduction in the network capacity of the entire system. Since the size of the transmission power interferes with other nodes adjacent to the node and is related to the topology of the network, and the topology of the multi-hop network is very complicated, each node itself needs to have an intelligent control mechanism, according to Individually owned environments and states randomly change their transmit power.

In accordance with the present invention, the transmit power of a transmit communication signal (e.g., a transmit enable signal) can be tuned to notify all other nodes that would interfere with the node transmitting the communication signal. In order to reduce interference, each node can adjust its transmit power to transmit signals with the minimum transmit power of the target node. In other words, each node can reach the minimum transmit power of all target nodes, and it will determine the range in which the node interferes with other nodes.

Referring to FIG. 3, in an embodiment of the present invention, a central node (ie, node 0) transmits a packet to a neighbor node (ie, nodes A, B, C, D, E), such as a protocol packet (Signal). Packe t) to identify all other nodes that will interfere with the central node. Therefore, the power of the transmitting protocol packet will determine the identity of the central node to its neighbor nodes. In an embodiment of the present invention, a method for each node in a wireless network to adjust its transmission power by itself is to set a maximum transmission power that the node transmits, that is, P, and the maximum transmission power can be achieved according to The minimum transmit power of the target node depends.

Next, each node in the wireless network can periodically send a packet to a central node, such as a Signal Packet, to enable the central node to identify neighboring nodes around it. According to the invention, the power of the protocol packet can be calculated by the following formula:

Protocol Packet Power (SP Power) = Maximum Transmit Power (P) + Signal to Noise Ratio (SNR).

Wherein, since the protocol packet needs to be demodulated by all other nodes that will receive interference, the transmission power of the protocol packet can be set to the maximum transmission power sent by the node, that is, P, and the signal to noise ratio (SNR is Signal- To-noise ratio) may be a signal to noise ratio of a transmission rate of a CTS (Clear to Send) signal.

In a preferred embodiment of the present invention, the specific application environment of each node device, including climate, weather, terrain, etc., may result in small differences between individual devices. Therefore, the present invention introduces a pair of environment variables. The system makes specific corrections. That is to say, the transmission power of the foregoing protocol packet can be set to the maximum transmission power sent by the node, that is, P, the sum of its signal-to-noise ratio and an environment variable, that is, ,

Protocol Packet Power (SP Power) = Maximum Transmit Power (P) + Signal to Noise Ratio (SNR) + Environment Variable (margin).

The signal-to-noise ratio (SNR) is, for example, the signal-to-noise ratio (SNR) of the transmission rate of the communication signal that allows the signal to be transmitted, and the environmental variable can be a detection variable, which is calculated by the RNC (RTS no CTS), and the specific calculation method For reference, refer to the PCT Patent of "Single Antenna Multichannel Wireless Communication Method and Apparatus".

In a preferred embodiment, in order to reduce the consumption of the entire system network resources by the protocol packet, the present invention further extends the period in which each node transmits the protocol packet and/or reduces the size of the protocol packet. According to the present invention, after the central node receives one or more protocol packets, the information of the protocol packet can be utilized to calculate the transmission power of the communication signal to be transmitted, for example, the transmission power of the transmission signal. In an embodiment of the invention, the transmission power of the communication signal is obtained by the following formula: Communication signal transmission power = maximum loss value Max (loss) + signal to noise ratio (SNR).

The maximum loss value can be obtained in a look-up manner in each neighbor node, and the signal-to-noise ratio is, for example, a signal-to-noise ratio of a transmission rate of a communication signal that allows a signal to be transmitted.

In a preferred embodiment of the present invention, the specific application environment of each node, including climate, weather, terrain, etc., may result in small differences between individual devices. Therefore, the present invention introduces an environment variable to the system. Make specific corrections. That is to say, the transmission power of the above communication signal can be set as the maximum loss value, that is, Max (loss), the sum of its signal-to-noise ratio and an environment variable, that is, ,

Communication signal transmission power = maximum loss value Ma _X (l _0SS ) + signal to noise ratio (SNR) + environment variable (margin).

The maximum loss value can be obtained in a look-up manner in each neighbor node, and the signal-to-noise ratio is, for example, a signal-to-noise ratio of a transmission rate of a communication signal that allows a signal to be transmitted, and the environmental variable can be a detection variable, by the RNC ( RTS no CTS) To calculate, the specific calculation method can refer to the PCT patent of "single antenna multi-channel wireless communication method and device", as described above.

In another preferred embodiment of the present invention, the transmission power of the communication signal can introduce a noise floor value to specifically modify the system. That is to say, the transmission power of the above communication signal can be set as the maximum loss value, that is, Max (loss), the sum of its signal-to-noise ratio and the environmental variable (margin) and a noise floor value. Value, that is,

Communication signal transmission power = maximum loss value Ma _X (l _0SS ) + signal to noise ratio (SNR) + environment variable (margin) + noise floor value (NP).

The maximum loss value can be obtained in a look-up manner in each neighbor node, and the signal-to-noise ratio is, for example, a signal-to-noise ratio of a transmission rate of a communication signal that allows a signal to be transmitted, and the environmental variable can be a detection variable, by the RNC ( RTS no CTS) to calculate, the specific calculation method, can refer to "single antenna multi-letter The PCT patent of the wireless communication method and apparatus of the channel has been as described above, and the noise floor can be the sum of all noise except the signal.

As shown in Figure 3, after receiving the protocol packets sent by the neighbor nodes A, B, C, D, and E, the node 0 will count the neighbors that may interfere with the packet transmission during the data packet transmission process. Nodes, ie nodes A, B, C, D, E. Node 0 looks up the table to get the loss value of node A, B, C, D, E and its maximum value, Max (loss). The transmission power of the communication signal allowing the transmission of the signal, for example, can be obtained by the above formula.

In still another embodiment of the present invention, reducing interference and enlarging the network capacity can be implemented by adjusting the transmission rate and transmission power of the communication signal, the details of which have been described above, and are not described again.

Thereby, the beneficial effects of the invention are as follows: 1. The anti-interference property is improved by quality; 2. The network capacity of the wireless network is greatly improved; 3. The price is low, the maintenance is convenient, and the service life is long; 4. The method is simple and realized. Easy and wide range of applications.

The present invention has been described in detail with reference to the preferred embodiments of the present invention. That is, the equivalent changes and modifications made by the scope of the present application should remain within the scope of the present invention.

Claims

Claim

A method for reducing communication interference in a wireless network, the method comprising: identifying a plurality of neighbor nodes of a central node;

Transmitting a first communication signal to the plurality of neighbor nodes, wherein the first communication signal is only sent to a node in the wireless network that is regarded by the central node as the plurality of neighbor nodes; a communication signal, when the central node performs data transmission with one of the plurality of neighbor nodes, the other nodes of the plurality of neighbor nodes do not send a data in a same channel, thereby reducing the wireless network Communication interference in.

The method according to claim 1, wherein the identifying step comprises: detecting a signal packet to treat a node that sends the signal packet to the central node as the central node Neighbor node.

The method of claim 1, wherein the first communication signal is an allowable transmission signal.

The method according to claim 1, wherein the method further comprises adjusting a power for transmitting the first communication signal.

The method according to claim 4, wherein the power is a maximum loss value between the central node and the neighbor node and a sum of a signal to noise ratio.

6. The method of claim 5 wherein said power further comprises an environmental variable.

The method according to claim 5, wherein the power further comprises a bottom noise value, which is a sum of all noises in the wireless network.

The method according to claim 2, wherein a power rate of transmitting the signal packet is a sum of a maximum power and a signal to noise ratio sent by the node.

9. The method of claim 8 wherein said power further comprises an environmental variable.

10. The method of claim 2, wherein the node periodically transmits the signal packet to the central node.

The method according to claim 1, wherein the method further comprises adjusting a rate at which the first communication signal is transmitted according to a size of the wireless network.

The method according to claim 1, wherein the method further comprises: transmitting a second communication signal, which may be sent first in preference to the first communication signal, so that the central node is according to the first Transmitting the first communication signal to the plurality of neighbor nodes.

The method according to claim 12, wherein said second communication signal is a request transmission signal.

The method according to claim 2, wherein the signal packet is a protocol packet.

The method according to claim 10, wherein the node is capable of adjusting a period of transmitting the signal packet to the central node or changing a size of the signal packet.

16. A system for reducing communication interference in a wireless network, the system comprising:

a receiving node, which can identify a plurality of neighboring nodes to send a first communication signal to the plurality of neighboring nodes, where the first communication signal is sent only to the wireless network, and the receiving node is regarded as a node of the plurality of neighboring nodes, according to the first communication signal, when the receiving node performs data transmission with one of the plurality of neighboring nodes, the other nodes of the plurality of neighboring nodes are not in the same channel Transmitting a data, thereby reducing communication interference in the wireless network.

The system according to claim 16, wherein the receiving node considers a node that sends a signal packet to the receiving node as the neighboring node.

18. The system of claim 16 wherein the first communication signal is a permission to transmit signal.

The system according to claim 16, wherein the receiving node is a power that can adjust to send the first communication signal.

The system according to claim 19, wherein the power is a maximum loss value between the receiving node and the neighboring node and a sum of a signal to noise ratio.

21. The system of claim 20, wherein the power further comprises an environmental variable.

22. The system of claim 20, wherein the power further comprises a noise floor value that is a sum of all noise in the wireless network.

The system according to claim 17, wherein a power of the signal packet sent by the neighboring node is a sum of a maximum power and a signal to noise ratio sent by the neighboring node. .

24. The system of claim 23, wherein the power further comprises an environmental variable.

25. The system of claim 17, wherein the neighbor node periodically transmits the signal packet to the receiving node.

The system according to claim 16, wherein the receiving node adjusts a rate at which the first communication signal is transmitted according to a size of the wireless network.

The system according to claim 16, wherein the system further comprises a sending node, configured to send a second communication signal to the receiving node, wherein the second communication signal may take precedence over the first A communication signal is sent, so that the receiving node sends the first communication signal to the plurality of neighbor nodes according to the second communication signal.

28. The system of claim 27, wherein the second communication signal is a request to transmit signal.

29. The system of claim 17, wherein the signal packet is a protocol packet.

30. The system of claim 25, wherein the neighboring node is operative to adjust a period of transmitting the signal packet to the receiving node or to change a size of the signal packet.