Channel selection method, channel selector and network connecting apparatus

Channel selection method, channel selector and network connection device

Channel selection method, channel selector and network connecting apparatus

The present invention relates to a channel selection method, in particular to a channel selection method, a channel selector and a network connection device that are suitable for wireless local area network connections and can dynamically and automatically find the best working channel to avoid mutual interference .

Direct Sequence Spread Spectrum (DSSS, Direct Sequence Spread Spectrum) is a method for radio frequency modulation in the license-free 2.4GHz ISM (Industrial Scientific Medical) frequency band. It can be used for wireless USB, 802.11b/g /a (generally called Wi-Fi, Wireless Fidelity, wireless fidelity) and 802.15.4 (called ZigBee, swarm bee). The Wi-Fi network defines 11 channels in the 2.412GHz~2.462GHz frequency band, and the ZigBee network divides the 2.405GHz~2.48GHz into 16 channels. Among them, the channels of each network are lowered according to the frequency of the channel. The highest provides incremental channel numbers.

ZigBee technology is a short-distance, low-complexity, low-power, low-data rate, low-cost, and high-capacity wireless sensor network technology. It is mainly suitable for businesses that carry a small amount of data, such as automatic control and remote The purpose of monitoring and other fields is to satisfy the wireless networking and control of small and inexpensive devices. Compared with various existing wireless communication technologies, ZigBee technology is the technology with the lowest power consumption and cost.

Contrary to ZigBee technology, WiFi is a long-distance, high-complexity, high-power, high-data rate (up to 54Mbps), and high-cost wireless network. Road technology. At present, it is widely used in wireless local area network, which is very convenient to access the Internet and is suitable for the market of schools, commercial buildings or home networks.

Because ZigBee and WiFi each have obvious characteristics, and many characteristics are complementary. Therefore, with the continuous growth of market demand for low-speed applications, it is more and more likely that Zigbee and Wi-Fi systems coexist. However, since both of them mainly work in the 2.4GHz ISM frequency band, mutual interference will inevitably occur. If the communication quality is poor, the network connected device is often required to retransmit and cannot efficiently transmit and receive data. If the command/receive response information cannot be sent immediately, it will cause a decrease in operating performance and increase the waste of power for the network connected device. Therefore, how to dynamically and automatically find the best working channel, avoid mutual interference, improve the operating efficiency of the network connection device and avoid the waste of power is the biggest issue at present.

Therefore, one of the objectives of the present invention is to provide a channel selection method and channel selector, which use software to memorize the error retransmission times and frequency hopping judgment mechanism of each channel, and switch channels according to the transmission efficiency, so that the interference can be selected. The smallest working channel.

Another object of the present invention is to provide a network connection device that can select a working channel with better communication quality to avoid power waste caused by incorrect retransmission.

Therefore, the present invention provides a channel selection method, which is suitable for determining a working channel for the network to communicate from among multiple candidate channels of a network, including the following steps: (A) Reading another network for communication One channel, and According to the channel that the other network communicates with, mark the channel that overlaps the other network for communication in a channel list where the candidate channels of the network are recorded, so as to determine the channel of the network. Wait for the candidate channels, and the candidate channels do not overlap with the channel on which the other network communicates, wherein the maximum data transmission rate of the other network is greater than the maximum data transmission rate of the network; (B) the network Evaluate the channel communication quality for each candidate channel of the channel, and select the candidate channel corresponding to the better channel communication quality as the working channel; (C) switch to the working channel for the network to communicate; (D) ) Transmit a packet and monitor the number of retransmissions of the packet; (E) Decide whether to update the working channel based on the number of retransmissions of the packet; Candidate channels evaluate the channel communication quality, and select the candidate channel corresponding to the better channel communication quality as the updated working channel; wherein the number of candidate channels of the network is less than the total number of supported transmission channels of the network .

In addition, the present invention provides a channel selector suitable for use in a network connection device for coupling a first network and a second network. The first network corresponds to at least one first channel, and the first network corresponds to at least one first channel. The two networks correspond to a plurality of second channels, and the channel selector includes: a marking unit that reads the at least one first channel of the first network for communication, and the at least one that communicates according to the first network A first channel, marking which second channels overlap with the at least one first network for communicating with the first network in a second network candidate channel list that records the second channels of the second network Channels to determine multiple candidate channels among the second channels, and the determined candidate channels do not overlap with the at least one first channel for communication on the first network, wherein The highest data transmission rate of the first network is greater than the highest data transmission rate of the second network; an evaluation unit evaluates the channel communication quality for each candidate channel to select the candidate channel corresponding to the better channel communication quality As a working channel for the network connection device to communicate with the second network; and a monitoring unit, when the network connection device transmits a packet to the second network via the working channel, the monitoring unit monitors The number of times the network connection device retransmits the packet to determine whether to make the evaluation unit update the working channel; wherein, when the monitoring unit causes the evaluation unit to update the working channel, the evaluation unit is the one other than the current working channel The candidate channel evaluates the channel communication quality, and selects the candidate channel corresponding to the better channel communication quality as the updated working channel; wherein the number of the candidate channels is less than the total number of the second channels.

Furthermore, the present invention provides a network connection device suitable for coupling a first network and a second network, the first network corresponds to a first channel, and the second network corresponds to a plurality of second channels , The network connection device includes: a first transceiver unit for communicating with the first network via the first channel; a second transceiver unit for communicating with the second network via a working channel And a processor, electrically connected to the first transceiving unit and the second transceiving unit, further comprising: a channel selector having: a marking unit that reads the first channel of the first network for communication, And according to the first channel that the first network communicates with, mark which second channel overlaps the first network in a second network candidate channel list that records the second channels of the second network The first channel through which a network communicates to determine multiple candidate channels among the second channels, and the determined candidate channels do not overlap The first channel for communication on the first network, wherein the maximum data transmission rate of the first network is greater than the maximum data transmission rate of the second network; an evaluation unit for evaluating channel communication for each candidate channel Quality, selecting the candidate channel corresponding to the better channel communication quality as the working channel; and a monitoring unit that monitors the number of times the second transceiver unit retransmits a packet on the working channel to determine whether to make the evaluation unit Update the working channel; wherein, when the monitoring unit causes the evaluation unit to update the working channel, the evaluation unit evaluates the channel communication quality for the candidate channels other than the current working channel, and selects the candidate corresponding to the better channel communication quality The channel is regarded as the updated working channel; wherein, the number of the candidate channels is less than the total number of the second channels.

The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of the two preferred embodiments with reference to the drawings.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are denoted by the same numbers.

<b>First preferred embodiment</b>

Referring to FIG. 1, the first preferred embodiment of the network connection device 300 of the present invention is suitable for coupling a first network 100 and a second network 200. The first network 100 corresponds to a plurality of first channels that can support transmission, and a plurality of first wireless devices c1 in the first network 100 can use one of the first channels to wirelessly connect to the network connection device 300. Similarly, the second network 200 corresponds to multiple second channels that can support transmission, and multiple second wireless channels in the second network 200 The device c2 can use one of the second channels to connect to the network connection device 300 wirelessly. Therefore, the first wireless device c1 and the second wireless device c2 can transmit data to each other.

Preferably, the first network 100 in this embodiment is a Wi-Fi wireless local area network, the second network 200 is a ZigBee wireless local area network, and the network connection device 300 is a Wi-Fi ZigBee network connection device. The first wireless device c1 is, for example, a wireless access point (WAP), mobile phone, computer, or other electronic devices with similar functions configured with Wi-Fi transceiving function, and the second wireless device c2 is, for example, configured with ZigBee transceiving function. Wireless speakers, lighting switches, air conditioners or other electronic devices with similar functions. The Wi-Fi ZigBee network connection device can have both Wi-Fi and ZigBee communication capabilities after the conversion of Wi-Fi and ZigBee formats, and the transmission rate (volume/frequency) of Wi-Fi is much higher than that of ZigBee and Wi-Fi. The power is also much higher than ZigBee. And referring to Figure 2, as those familiar with the art know, Wi-Fi wireless local area network can support the first channel including 11 channels in the 2.412GHz~2.462GHz frequency band, and the ZigBee wireless network can support the second channel including 16 channels located in the 2.405GHz~2.48GHz frequency band. Please note that the supported channels of these two networks overlap with each other, so ZigBee transmission will be adapted to Wi-Fi and use other working channels with better signal strength.

Through these channels, for example, mobile phones can transmit data to, for example, lighting switches via Wi-Fi ZigBee network connection devices to achieve remote control and management effects.

1 and 3 at the same time, the network connection device 300 includes a first transceiver unit 4, a first interface 3, a processor 2, a second Two interfaces 5 and a second transceiver unit 6. In addition, the network connection device 300 also includes a storage 1 electrically connected to the processor 2. In addition, the processor 2 includes a filtering unit 21, a format converter 22 and a channel selector 23. The memory 1 stores an address table, which records the addresses of the first wireless device c1 and the addresses of the second wireless device c2.

Taking this embodiment as an example, preferably, the processor 2 is a microcontroller (Micro-control Unit, MCU), and the first interface 3 is SDIO (Secure Digital Input/Output, Secure Digital Input/Output) suitable for Wi-Fi wireless networks. Digital input/output) interface, the first transceiver unit 4 is a Wi-Fi network interface device, and the second interface 5 is a UART (Universal Asynchronous Receiver/Transmitter) interface suitable for ZigBee wireless networks. The second transceiver unit 6 is a ZigBee network interface device.

The Wi-Fi ZigBee network connection device 300 has a Wi-Fi network interface device, a microcontroller, and a ZigBee network interface device, which can communicate commands and data through an SDIO interface and a UART interface. The microcontroller is responsible for receiving the commands from the first network through the Wi-Fi network interface device and the SDIO interface, interpreting them into ZigBee commands (ZCL commands), and then transmitting them to the ZigBee network interface devices through the UART interface After the second network, the ZigBee network interface device then sends the result or status of the second network back to the microcontroller, and then converts it into a Wi-Fi format to reply to the first network. In the same way, the Wi-Fi ZigBee network connection device 300 can also receive commands from the second network, interpret them into Wi-Fi commands and send them to the first network, and then reply to the results or status of the first network To the second network.

Use one of the first network 100 and the network connection device 300 When a channel is accessed, the channel selector 23 is used to mark which second channels overlap the first channel used by the first network 100 in the second network candidate channel list, and the remaining second channels are Candidate channel. Wherein, the second network candidate channel list is a list in which the second network candidate channels are recorded.

The channel selector 23 selects one of the candidate second channels as a working channel for communicating with the second network 200, and the selected second channel does not overlap the first network 100 and the network connection device 300 The first channel used during the time. The aforementioned first channel used may be determined by the first wireless device c1 or designated by the user. The first transceiver unit 4 receives a first packet from the first network 100 via the first channel used for access, and sends it to the filtering unit 21 through the first interface 3. The filtering unit 21 analyzes a source address and a destination address contained in the first packet, and compares the records in the address table to determine which first wireless device c1 of the first network 100 transmits the first packet. For which wireless device on which network.

When the filtering unit 21 determines that the first packet is one of the first wireless devices c1 of the first network 100 to be transmitted by one of the second wireless devices c2 of the second network 200, the format converter 22 will match the first network The first packet of the 100 transmission format is interpreted into a second packet that conforms to the transmission format of the second network 200, and then transmitted through the second interface 5 and the second transceiver unit 6. Wherein, the second transceiver unit 6 transmits the second packet to the second wireless device c2 pointed to by the destination address in the second network 200 via a second channel selected from a candidate channel list.

On the contrary, the network connection device 300 receives the first transmission from the second network 200 In the case of the second packet, the second packet can also be interpreted into the first packet conforming to the transmission format of the first network 100 in a similar manner as described above, and then provided to the first network 100.

More specifically, both the first network 100 and the second network 200 mainly work in the 2.4 GHz frequency band, and the communication quality of each channel is uneven, so the channel selector 23 specifically implements the preferred embodiment of the channel selection method of the present invention. Optimize packet transmission efficiency. The channel selector 23 has an evaluation unit 24, a monitoring unit 25, and a marking unit 26, and the channel selection method includes the following steps in FIG. 4.

Step 70: The marking unit 26 reads the first channel currently used to access the first network.

Step 71: When the marking unit 26 reads the first channel currently used for access, mark which second channels overlap with the first channel currently used for access in the second network candidate channel list, and treat other channels as The second channel is a candidate channel to be evaluated. If the first channel currently used for access is not read, all second channels are regarded as candidate channels, and all candidate channels are not marked at this time. In this embodiment, the channels occupied by Wi-Fi are marked on the ZigBee channel list, and other unmarked channels are candidate channels available for ZigBee.

Step 72: The evaluation unit 24 evaluates a quality signal of each unmarked candidate channel. Preferably, the quality signal in this embodiment is a Link Quality Indicator (LQI). However, for example, the Receive Signal Strength Indicator (RSSI) or other quality signals that can show the quality of channel communication can also be used as an indicator for evaluating the quality of packets. Mark.

The evaluation process of each unmarked candidate channel is: first, the second transceiver unit 6 transmits a quality detection packet to one of the second wireless devices c2 via the candidate channel, and receives the return from one of the second wireless devices c2 After the quality response packet, the corresponding quality signal is calculated based on the strength and quality of the quality response packet.

Of course, in another aspect, the second transceiver unit 6 may also broadcast the quality detection packet to all the second wireless devices c2, and the evaluation unit 24 will evaluate the quality response packets returned by all the second wireless devices c2 to calculate A quality signal.

Step 73: The evaluation unit 24 selects the candidate channel with the best quality signal (the channel with the least interference) as a working channel, and causes the second transceiver unit 6 to broadcast a frequency switching instruction packet to notify all the second wireless devices c2 that they are about to Switch to the working channel to receive the packet. In particular, the frequency change here refers to changing to another second channel, that is, frequency hopping.

Step 74: The evaluation unit 24 makes the second transceiver unit 6 switch to the working channel as the basis for transmitting the second packet.

Step 75: As time passes, the second transceiver unit 6 will sequentially send out a plurality of second packets. The monitoring unit 25 updates the maximum number of retransmissions according to the number of retransmissions of the same second packet by the second transceiver unit 6 at regular intervals, until the maximum number of retransmissions exceeds a retransmission threshold, and then skips to step 76.

In other words, when the number of retransmissions of the packet on the working channel is not higher than the preset retransmission threshold, the monitoring unit 25 continues to monitor the maximum number of retransmissions of each packet; when the number of retransmissions of the packet on the working channel Above the retransmission gate When the threshold is reached, the process jumps to step 76.

The so-called number of retransmissions refers to the number of times that the second wireless device c2 pointed to by the destination address requests to retransmit the second packet after the second transceiver unit 6 sends a second packet. Generally, the worse the communication quality of the working channel, the easier it is to be required to retransmit.

The monitoring unit 25 mainly updates the maximum retransmission times with the current retransmission times when the current retransmission times&gt; the maximum retransmission times. In this embodiment, preferably, when the second transceiver unit 6 sends a second packet every 1 second, the retransmission threshold=10, but it is not limited to this. The retransmission threshold can be adjusted according to the desired transmission efficiency. And change.

Step 76: When the number of retransmissions of the packet on the working channel is higher than the retransmission threshold, the marking unit 26 marks the working channel in the second network candidate channel list.

Step 77: The monitoring unit 25 checks whether the number of unmarked candidate channels is lower than an unmarked threshold. If yes, clear the mark of the second network candidate channel list, and then skip back to step 72. If not, skip back to step 72 directly.

Therefore, as long as the maximum number of retransmissions of the current working channel is too large, the channel selector 23 judges that the transmission efficiency is not good and further selects another candidate channel with better communication quality to update the working channel to effectively maintain high-efficiency transmission performance.

The channel selector 23 can be a piece of software or a piece of hardware. Preferably, in this embodiment, a software recording the channel selection method is written in the processor 2, and the software is used to memorize the frequency hopping judgment mechanism of each channel, and record the number of error retransmissions in the memory 1 in.

In addition, the preferred unmarked threshold of this embodiment is not less than a quarter of the total number of second channels (total=16). For example, the unmarked threshold can be selected as 5. When the number of unmarked candidate channels is lower than the unmarked threshold, working channels can only be selected from a few channels, and it is not easy to maintain high transmission efficiency. In addition, the channel quality changes with time. The previously marked channel may have improved communication quality at this time. Therefore, this embodiment specifically clears the mark of the second network candidate channel list when the number of unmarked candidate channels is too small, and then Re-evaluate the communication quality of all candidate channels.

It should be reminded that if there is a change in the first channel for communication, the flow of the channel selection method will jump back to step 71 to redefine the candidate channel. This is because the highest data transmission rate of the first network 100 is higher than that of the second network 200, and the transmission power is also higher. Better quality channels are needed to maintain high transmission efficiency. Therefore, the first network 100 is given priority to select the desired Channel.

In this embodiment, the microcontroller (MCU) of the network connection device 300 learns the first channel currently used by Wi-Fi, so that the channel selector 23 knows which of the remaining second channels are available, and the ZigBee network interface device then These candidate second channels send signals to measure the LQI value (Link Quality), and the channel with the maximum LQI that can be found is preset as the working channel with the least interference (the new channel to be used).

In summary, since the Wi-Fi ZigBee network connection device plays the role of Coordinator in the ZigBee network, it can send broadcast packets before frequency hopping to notify the second wireless device c2 (such as routers and terminals) to which it belongs. The device (End device) is switched to the new channel.

During operation, as long as the memory and statistics errors are repeated when sending/receiving packets The number of transmissions. If the number is higher than the set maximum value, the channel is marked as having great interference, and then the signal is sent to other available channels, and the LQI value (Link Quality) is measured. The channel with the maximum value of LQI is found The next available working channel, and notify other devices to switch to the new channel.

Since the continuous increase of the mark on the ZigBee channel list will result in fewer and fewer available channels, the "Minimum Available Channels (ie unmarked threshold)" will be set. If the number of available channels is lower than this value, Wi-Fi will be cancelled. -For markers other than the Fi channel, re-measure the LQI value to determine the new working channel.

Moreover, the present invention is suitable for wireless transmission between two devices with different transmission rates. Although the aforementioned first network 100 is a Wi-Fi wireless local area network, and the second network 200 is a ZigBee wireless local area network, this embodiment can also be applied to other network types, as long as it meets the requirements of the first network 100. The maximum data transmission rate may be greater than the maximum data transmission rate of the second network 200. Of course, when the types of the first network 100 and the second network 200 are changed, the types of the first interface 3 and the second interface 5 also need to be adjusted accordingly. Usually operating in the 2.4GHz frequency band and using DSSS (Direct Sequence Spread Spectrum) technology, there are wireless USB (universal serial bus, universal serial bus), 2.4GHz wireless phones and CDMA (Code Division Multiple Access, The code division multiple access) system can be selected as the first network 100 or the second network 200 in this embodiment.

It is worth noting that the channel selector 23 can also be independent of the network connection device 300, and the implementation of the network connection device 300 is not limited to a bridge, and can also be a gateway, a router, or others. In addition, storage 1 can also So it is built into the processor 2'as shown in Figure 5.

<b>The second preferred embodiment</b>

Referring to FIG. 6, the network connection device 300" of the second preferred embodiment can use the second network to connect to a plurality of second wireless devices c2, wherein the network connection device 300" does not have a display device or an input device, and cannot directly Connect to an external network.

In order for the network connection device 300" to use the first network connection as the wireless service providing device c1' of the first wireless device, firstly the portable wireless device c1" as another first wireless device will be connected to the network connection device 300" establishes an ad-hoc wireless network. After that, the portable wireless device c1" sends the information used to log in to the first network to the network connection device 300". Then, the network connection device 300" Use the received login information to connect to the first network to communicate with the wireless service provider c1'.

Preferably, the first network in this embodiment is a Wi-Fi wireless local area network, and the second network is a ZigBee wireless local area network. The network connection device 300" is a Wi-Fi ZigBee network connection device; the wireless service providing device c1' is, for example, a wireless sharing device (Wireless Access Point, WAP); the portable wireless device c1" is, for example, configured with Wi-Fi transceiver Functional mobile phones, computers, or other electronic devices with similar functions; the second wireless device c2 is, for example, a wireless speaker, a lighting switch, an air conditioner or other electronic devices with similar functions configured with ZigBee transceiver functions. In particular, the method of establishing a connection between the portable wireless device c1" and the network connection device 300" of the present invention is not limited to the foregoing description, as long as it is a reasonable network connection, such as an Ethernet network. At the same time, the aforementioned network connection device 300" is not limited to not having display equipment or output The device is connected to the device and cannot be directly connected to the external network.

In this way, when the network connection device 300" and the wireless service provider device c1' communicate via a first channel, the network connection device 300" can select the best communication quality from the second channel that does not overlap the first channel. To establish a connection with the second wireless device c2 (the details are as described in the first embodiment, and will not be repeated here), so that the portable wireless device c1" can remotely control and manage these second wireless devices Device c2.

In summary, the channel selection method, channel selector, and network connection device of the foregoing preferred embodiment have the following advantages:

(1) With a channel memory mechanism, the network connection device selects a suitable working channel from those second channels that do not overlap the first channel currently accessed by the first network, so as to achieve the effect of avoiding channels with high interference.

(2) Reduce the frequency of error retransmissions of network connected devices and improve network operation efficiency.

(3) Select the working channel with better communication quality, so that the network connection device can avoid the waste of electric energy caused by wrong retransmission.

However, the above are only preferred embodiments of the present invention, and should not be used to limit the scope of implementation of the present invention, that is, simple equivalent changes and modifications made in accordance with the scope of the patent application of the present invention and the description of the invention, All are still within the scope of the invention patent.

<p>100First Network</p><p>25Monitoring unit</p><p>200Second Network</p><p>26Marking Unit</p><p>300Network connection device</p><p>3First interface</p><p>300'Network connection device</p><p>4The first transceiver unit</p><p>300"Network connection device</p><p>5Second interface</p><p>1Storage</p><p>6Second transceiver unit</p><p>2, 2' processor</p><p>70~77step</p><p>21Filter unit</p><p>c1First wireless device</p><p>22Format Converter</p><p>c1'Wireless service provider</p><p>23Channel selector</p><p>c1"Portable wireless device</p><p>24Evaluation Unit</p><p>c2Second wireless device</p>

Figure 1 is a schematic diagram illustrating a first embodiment of a network connection device for coupling a first network and a second network; Figure 2 is a schematic diagram illustrating that the first channel and the second channel are located 2.4GHz frequency band; Figure 3 is a block diagram illustrating the network connection device of the first preferred embodiment; Figure 4 is a flowchart illustrating a preferred embodiment of the channel selection method of the present invention; Figure 5 is a block diagram, Illustrate another aspect of the network connection device; and FIG. 6 is a schematic diagram illustrating the second preferred embodiment of the network connection device.