JP4180758B2 - Wireless network, route control method thereof, and wireless communication control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wireless network composed of a plurality of wireless communication control devices, and more particularly to a route control method for a wireless communication control device.
[0002]
[Prior art]
In recent years, with the advance of computer networks for exchanging data between computers, it has become widespread not only for business operators that perform communication service work but also for data communication within and between companies. Furthermore, the demand for introducing network communication is spreading to small offices, supermarkets, general households, and the like. However, until now, the network technology has mainly been a wired system that interconnects computers with cables, and places such as supermarkets where the placement of computers changes frequently, or homes and small scales where it is difficult to lay the cables themselves In the office, it was difficult to introduce a network.
[0003]
As a method for solving these cable laying problems, attention is paid to a wireless network instead of a cable. In order to construct a wireless network, it is necessary to establish communication between specific adjacent wireless stations. For example, each radio station can perform communication with a specific radio station by dividing a band into a predetermined pattern by a frequency hopping method defined in the international standard IEEE802.11. That is, since communication is established only between wireless stations having the same frequency hopping pattern, communication between other wireless stations is not received by mistake.
[0004]
A radio station secures a communication line only with a specific adjacent station, and then determines a logical network configuration based on an SSID (system ID number) assigned to each radio station. At this stage, only a logical network is configured, so there are multiple network paths between wireless stations via relays of wireless stations, and which path to select depends on the logical network. This is done by a higher-level program than the programmed program.
[0005]
A common method of band sharing in a wireless network is the CSMA / CA method. As described in the standard IEEE802.11, this method performs carrier sense, confirms that no radio station is outputting data (transmission wave), and performs data transmission. If the transmission waves of multiple wireless stations collide and the data does not reach the other station, the other station does not return a response to the transmitted data, so the transmitting station times out until the response is received, The transmitting station detects that the transmission wave has not reached due to wave collision or disturbance.
[0006]
[Problems to be solved by the invention]
Since wireless networks do not require cable laying, they have been used in the construction of networks that are small and have a short distance between computers. However, application of a wireless network is also demanded for a large-scale trunk network that has been realized only by a wired network.
[0007]
However, there are various disturbance factors that emit or reflect radio waves as well as other nearby radio communication devices in the communication environment of a wireless network. There is a feature that does not exist in a wired network that changes over time. For this reason, the frequency of communication failures is higher than that of wired communication, and the bit error rate is about 10 to 100 times higher. In addition, even a communication line once determined may become abnormal during use and communication may be interrupted. On the other hand, abnormalities in wireless communication are often transient, and there is a feature that the line quality is quickly restored as time passes.
[0008]
In addition, when a plurality of sets of wireless communication apparatuses communicate with each other, the bandwidth must be shared, so that the data transfer throughput is reduced. When a plurality of wireless networks exist and use the same frequency band, communication may be performed using the band in a time division manner, for example, in order to share the band so as not to interfere with mutual communication. Therefore, if there are a plurality of wireless networks that perform communication, the data transfer throughput decreases by the number of the networks. Even when a plurality of wireless networks are separated from each other and usually do not affect each other, there may occur a situation where mutual wireless communication is temporarily received and a band must be shared. In a wired network, cables for each network are laid, so a plurality of networks do not share a band.
[0009]
That is, in a wireless network, data transfer cannot be performed stably because data transfer temporarily cannot be performed temporarily or portions where the data transfer throughput is reduced frequently occur. Since the data transfer is not stable, packet (frame) loss occurs, retransmission in the upper protocol or frame retransmission between relay devices occurs frequently, and transmission delay increases. This is a limitation in applying a wireless network to a large-scale backbone network with a long data transmission distance.
[0010]
An object of the present invention is to provide a data transmission path control method for a wireless network that ensures the performance and reliability of data transfer and enables stable data transfer, and a large-scale backbone network Is to realize the wireless network.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has a plurality of paths for transmitting data from a communication control apparatus serving as a transmission source to another communication control apparatus serving as a transmission destination among a plurality of communication control apparatuses having a wireless communication function. In a wireless network configured as described above, a route or a plurality of routes in which a route information that can be investigated for route information is transmitted from the transmission source to the transmission destination, and the line quality based on the route information acquired through the frame becomes a certain level And a transfer route control function for determining a route with the highest line quality as a use route.
[0012]
The path information is the communication time, the number of retries, or the line load of the frame in a one-way or round-trip path for transmitting the frame from the transmission source to the transmission destination. The smaller the value of the path information, the more the line quality It is characterized by high evaluation.
[0013]
The transfer path control function includes a frame issuance unit capable of examining the path information and a path determination unit that determines a use path based on the received path information. Or it is implement | achieved by the structure linked as a relay station.
[0014]
In addition, the present invention provides data transfer between a plurality of communication control devices having a wireless communication function from a communication control device serving as a transmission source to another communication control device serving as a transmission destination directly or via another communication control device. In a wireless network configured to have a plurality of routes to be transmitted, route information on the route using a route information area provided in a data frame from the source during communication from the source to the destination The transmission destination is compared with the value of the abnormality detection threshold value and the value of the route information area, and when the value of the route information exceeds the abnormality detection value, the abnormality of the communication route is detected, and the abnormality is transmitted to the transmission source. A line abnormality detection function for notifying occurrence is provided.
[0015]
In addition, the transfer route control function is provided, and when the transmission source knows that an abnormality has occurred in the used route, it transmits a frame in which the route information can be investigated to the destination through at least all other routes outside the used route. In addition, it is possible to switch to a route having a good route quality.
[0016]
The wireless network path control method of the present invention has a plurality of paths for transmitting data from a communication control apparatus serving as a transmission source to another communication control apparatus serving as a transmission destination among a plurality of communication control apparatuses having a wireless communication function. In a wireless network configured to, a route investigation frame for examining route information for all routes from the transmission source to the transmission destination when communication from the transmission source to the transmission destination is started or resumed Based on the route information of the route survey frames of the plurality of routes received by the destination, or the route information of the plurality of route survey frames received by the source by returning each route at the destination. It is characterized in that the route used is determined by judging the line quality of the route.
[0017]
The transmission destination or the transmission source receives the route investigation frame from a plurality of routes, and determines that the route received first is the route with the best channel quality with the shortest communication time.
[0018]
In addition, a communication control device having an area for storing the number of retries as the route information in the route check frame, and relaying a route check frame from the transmission source to the transmission destination or a return route check frame is the route check frame. The number of retries that occurred when transmitting the frame to the next communication control device is accumulated in the area for storing the number of retries in the route investigation frame, and the route investigation frame received by the transmission destination or the transmission source from a plurality of routes The number of retries is compared, and the route with the smallest accumulated number of retries is determined as the route with the best line quality.
[0019]
A communication control device having an area for storing a line load in the route check frame and relaying a route check frame from the transmission source to the destination or a return route check frame The line load obtained when the current line load is obtained when transmitting to the communication control device and the line load obtained from the value of the line load stored in the route investigation frame is large. And the line load in the route investigation frame received by the transmission destination or the transmission source from a plurality of routes is compared, and the route with the smallest line load is determined as the route with the best line quality.
[0020]
The line load is represented by a value obtained by dividing the number of bits of a frame transmitted / received to / from the next-stage communication control apparatus by a predetermined time before the present time by a line bandwidth between the next-stage communication control apparatus. Features.
[0021]
The wireless communication control device of the present invention is one of a plurality of communication control devices constituting a wireless network, and becomes a transmission station, a reception station, or a relay station from a transmission source (transmission station) to a transmission destination (reception station). A wireless communication function for transmitting data to one of the plurality of routes, a route information area, and a frame information from which the route information of the route from the transmission source to the transmission destination can be acquired. A transmission unit; a path information acquisition unit that updates path information of a received frame based on path information obtained by the own apparatus; and a path determination unit that determines a use path based on path information of frames received from a plurality of paths. And at least one of the above means is executed depending on whether the own apparatus is a transmitting station, a receiving station or a relay station.
[0022]
Further, the data frame transmitted from the transmission source to the transmission destination has the route information area, and the route information of the used route is acquired from the data frame during data communication, and a preset abnormality detection threshold value is set. In comparison, an abnormality detection means is provided for detecting an abnormality of the used route when the value of the route information of the used route exceeds a threshold value.
[0023]
According to the present invention, when a temporary deterioration of the line quality occurs between wireless communication devices on a wireless network, data transfer is temporarily delayed or a path where data transfer itself cannot be performed occurs. The communication control device of the transmission source or the communication control device of the data transmission destination detects a drop in line quality from the time required for data transfer, the number of data transfer retries between the wireless communication devices, or the line load between the wireless communication devices. By switching data transfer from a route with reduced quality to a route with no deterioration in line quality, a data transfer route is secured and data communication is continued.
[0024]
In addition, since the data transfer performance and reliability can be ensured by securing the data transfer path, stable data transfer can be realized in the wireless network.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a plurality of embodiments of a wireless network and a transfer route control method thereof according to the present invention will be described. In the first embodiment, a transfer path control method performed in a wireless network between a transmission source and a transmission destination at the start of transmission will be described. In the second embodiment, a transfer route monitoring and control method performed in a wireless network between a transmission source and a transmission destination during transmission will be described.
[0026]
[First Embodiment]
FIG. 2 shows an embodiment of a wireless network to which the present invention is applied. This wireless network includes wireless communication control devices 100, 110, 120, 130, 140, wireless terminals 101, 102, 103, 121, 122, 123, and the like, and constitutes a ring-shaped wireless network. For convenience of explanation, only the wireless terminals connected to the wireless communication control devices 100 and 120 are shown, but similar wireless terminals are also connected to other wireless communication control devices.
[0027]
In order to configure a ring network, each wireless communication control device can communicate with the other two wireless communication devices as shown by the arrows in the figure. For example, the wireless communication control device 100 can communicate with the wireless communication control devices 110 and 140 through the routes (1) and (2). Further, data transfer with the wireless communication control device 120 that cannot perform direct communication is performed by relaying the wireless communication devices 110 and 130 on the route (1) and the wireless communication device 140 on the route (2). The same applies to other wireless communication apparatuses. The line abnormality detection threshold storage unit 211 stores a threshold value indicating how many times the number of retries or the line load is detected as a line abnormality, and is referred to in the operation of the second embodiment described later. The
[0028]
FIG. 1 shows a configuration of a wireless communication control apparatus according to an embodiment of the present invention. The wireless communication control device 100 includes a control unit 200, a timer 201, a demodulator 202, a bandpass filter 203, a reception mixer 204, a frequency synthesizer 205, a transmission mixer 206, a modulator 207, a transmission / reception buffer 208, an antenna 209, a transmission / reception changeover switch 210, The line abnormality detection threshold value storage unit 211 is configured. The same applies to other wireless communication apparatuses.
[0029]
Here, the control unit 200 of the radio communication control apparatus 100 controls the entire system, and transmits the frame information acquisition means described in “Means for Solving the Problems” and the route information in the own apparatus. The path information acquisition means for updating the path information of the calculated and received frames and the path determination means for determining the used path based on the path information of the frames received from a plurality of paths are realized by software functions described later. . The same applies to the abnormality detection means according to the second embodiment.
[0030]
A basic operation of data transmission in radio communication control apparatus 100 will be described. The control unit 200 generates a data frame including a transmission destination address, a transmission source address, and data, and stores the data frame in the transmission / reception buffer 208. At the time of transmission, the control unit 200 switches the transmission / reception changeover switch 210 to the output of the transmission mixer 206, reads the data frame from the transmission / reception buffer 208, and outputs it to the modulator 207. The data frame modulated by the modulator 207 is sent to the transmission mixer 206, placed on a carrier wave generated by the frequency synthesizer 205, and transmitted to another radio communication control apparatus via the antenna 209. On the other hand, the reception mixer 204 receives the signal tuned to the carrier frequency from the frequency synthesizer 205, modulates the frequency, and demodulates the data frame of the digital data by the demodulator 202 via the band pass filter 203. The received data frame is sent to the control unit 200 and stored in the transmission / reception buffer 208.
[0031]
FIG. 3 shows a configuration of a plurality of data frames used for transmission / reception. The frame (a) includes a preamble 300, a transmission destination address 301, a transmission source address 302, a route 303, data 304, and a CRC (Cyclic Redundancy Code) 305. A route 303 is a field indicating the transfer route of this frame, and indicates either the route (1) or the route (2) in FIG. On the other hand, the frame (b) has a retry count 306 field, and the frame (c) has a line load 307 field. The line retry count 306 or the line load 307 is transferred and stored in the transmission / reception buffer 208. .
[0032]
In the transfer path control system according to the first embodiment, the frames shown in FIGS. 3A, 3B, and 3C are applied to Example 1, Example 2, and Example 3 described below, respectively.
[0033]
[Example 1]
Embodiment 1 of the transfer route control method is a method for determining a route in which a frame is received earliest among a plurality of routes as a transfer route. Hereinafter, an example in which the wireless terminal 101 transfers data to the wireless terminal 123 will be described. explain.
[0034]
The wireless terminal 101 transfers data to the wireless communication control apparatus 100. The wireless communication control device 100 frames the data from the wireless terminal 101 and transfers it to the wireless communication control device 140 on the route (1) or the wireless communication control device 110 on the route (2). When the wireless communication control device 110 receives the data frame, the data is transferred to the wireless communication control device 120. On the other hand, when the wireless communication control device 140 receives the data frame, the data frame is transferred to the wireless communication control device 120 via the wireless communication control device 130. The wireless communication control device 120 that has received the data frame recognizes that the data transfer destination is the wireless terminal 123 and transfers the received data to the wireless terminal 123.
[0035]
At the start of this data transmission, routes (1) and (2) are routed between the wireless communication control device 100 as the transmission side (transmission source) and the wireless communication control device 120 as the reception side (transmission destination) in the wireless network. The transfer route is determined by transmitting and receiving the route investigation frame. Here, a case will be described in which there is an abnormality in the route (2) and the route (1) is normal as shown in FIG. The route investigation frame to be used has the same format as the data frame in FIG. However, since the data 304 only needs to be checked for normal reception at the receiving destination, it may be test data.
[0036]
FIG. 4 illustrates a flow of communication frames when the transmission destination determines a route in the first embodiment. The destination wireless communication control device 120 is described in the center and the transmission source wireless communication control device 100 is described at both ends so that it is easy to compare the frame flows of both paths (1) and (2) (actually 1 One). The wireless communication control device 100 simultaneously transmits a route investigation frame on the right route (1) and the left route (2).
[0037]
The route investigation frame transmitted to the route (1) is received by the wireless communication control device 140. The wireless communication control device 140 uses the CRC 305 in the frame to confirm whether the route investigation frame data has been correctly received. If it is received correctly, a reception response is returned to radio communication control apparatus 100 that is the previous transmission side. The wireless communication control device 130 that relays the frame after the wireless communication control device 140 and the wireless communication control device 120 that finally receives the frame also perform the same confirmation, and if the frame is correct, a reception response is sent to the previous wireless communication control device. return. By these procedures, the route investigation frame is received by the wireless communication control device 120 through route (1).
[0038]
On the other hand, the route investigation frame transmitted on the route (2) is transmitted from the wireless communication control device 100 to the wireless communication control device 110, but the communication line between the wireless communication control devices 100 and 110 is wirelessly communicated due to radio interference or the like. The control device 110 cannot receive correctly and cannot return a reception response to the radio communication control device 100. The wireless communication control device 100 monitors the reception response from the wireless communication control device 110 by the timer 201 in the device after transmitting the investigation frame, but the time-out occurs because the reception response does not return. Therefore, radio communication control apparatus 100 retries (retransmits) transmission of the route investigation frame to radio communication control apparatus 110.
[0039]
In the figure, the wireless communication control device 110 correctly receives the route investigation frame and returns a reception response to the wireless communication control device 100 in the second retry. As a result, the route investigation frame transmitted to the route (2) is received by the wireless communication control device 120 via the wireless communication control device 110. Note that communication is interrupted when the predetermined maximum number of retries is exceeded.
[0040]
Upon receiving the route investigation frame from route {circle around (1)} and route {circle around (2)}, the wireless communication control device 120 that has received the route investigation frame receives one of the following three depending on the configuration of the route investigation frame to be used. The route is determined by any method. When the route investigation frame having the format shown in FIG. 3A is used, the wireless communication control device 120 passes the route investigation frame received earlier among the two route investigation frames that have passed the route (1) and the route (2). The route {circle around (1)} is determined as the route to be used. Then, the route response frame in which the route {circle around (1)} is set in the route 303 of the route frame is returned to the source wireless communication control device 100 via the wireless communication control devices 130 and 140. The wireless communication control device 100 sets the route {circle around (1)} as the frame transmission route to the wireless communication control device 120 from the route information of the response frame, and transmits the frame to the wireless communication control device 120 via the route {circle around (1)}.
[0041]
In this embodiment, the route investigation frame is transmitted from the transmission source to the transmission destination by two routes, the route of the route investigation frame received by the transmission destination is determined as the transfer route, and the transmission source is notified by the route response frame. Therefore, it is possible to shorten the time required for determining the route of the wireless network.
[0042]
As a modification of the first embodiment, the transmission destination does not determine the route, but transmits a route response frame that returns the same route, and the transmission source determines the route of the route response frame received earlier as the transfer route. Good.
[0043]
FIG. 5 shows a flow of a communication frame when the transmission source determines a route, and is described in the same format as FIG. The wireless communication control device 100 transmits a route investigation frame to the route (1) and the route (2). The route investigation frames transmitted to the route {circle around (1)} and the route {circle around (2)} reach the wireless communication control device 120 in the same procedure as in the case of FIG. On the other hand, the route investigation frame transmitted on the route {circle around (2)} is not correctly transmitted on the line between the wireless communication control devices 100 and 110 due to radio wave interference, and a retry occurs.
[0044]
Receiving the route investigation frame from the route (1) and the route (2), the wireless communication control device 120 returns the route response frame to the wireless communication control device 100 according to the same procedure. The wireless communication control apparatus 100 determines the route set in the route 303 of the previously received frame among the route response frames received from the routes (1) and (2) as the transfer route. In general, route determination by a transmission source can improve reliability compared to determination of a transmission destination. However, both methods have their own advantages and disadvantages, and a detailed comparison will be described later.
[0045]
[Example 2]
Embodiment 2 of the transfer route control method is a method of determining a route having the smallest number of retries as a transfer route among a plurality of routes, and hereinafter, a route investigation frame is transmitted from the wireless communication control device 100 to the wireless communication control device 110. An example will be described. The route investigation frame applied to the second embodiment has the same format as the frame of FIG. That is, the area of the retry count 306 for accumulating and storing the number of retry times of the route investigation frame performed by each wireless communication control device until the route investigation frame is transferred from the wireless communication control device 100 to the wireless communication control device 120. Have.
[0046]
FIG. 7 shows a flow of transmission processing of the wireless communication control device including the retry count update. This processing procedure is controlled by the control unit 200. When the wireless communication control device receives the route investigation frame from the preceding wireless communication control device (s101), it checks the transmission destination address 401 and CRC 305 in the route investigation frame (s102). If it is confirmed from the destination address 301 that the route check frame is not addressed to itself, the received route check frame is transmitted to the next stage wireless communication control device (s103). After transmitting the route investigation frame, the reception response from the radio communication control device at the next stage is monitored by the timer 201 in the device (s104). When the reception response is returned before the timer 201 times out, the transmission operation of the route investigation frame is ended. However, if there is no reception response and the timer 201 times out, the retry count 306 of the route investigation frame is read, and 1 is added to the value (s105).
[0047]
When the wireless communication control apparatus first transmits a route investigation frame, 0 is written in the retry count 306. When 1 is added to the retry count 306, the route investigation frame is transmitted again to the next-stage radio communication control apparatus (s103). Retries are repeated until the number of retries set in advance in the line abnormality detection threshold unit 211 is reached, and the value of the number of retries 306 in the route investigation frame is accumulated.
[0048]
FIG. 6 illustrates a flow of a communication frame when the transmission destination determines a route in the second embodiment. The value of the number of retries 306 on the route investigation frame received by the wireless communication control device 120 through the route (1) is 0, and the value of the number of retries 306 through the route (2) is 2. The wireless communication control device 120 compares the retry count 306 of the route investigation frame that has passed the route {circle around (1)} and the route {circle around (2)}, and controls the wireless communication control device 100 and the wireless communication control for the route {circle around (1)} having a smaller value of the retry count 306. The transfer route between the devices 120 is determined. Then, a route response frame is transmitted to the determined route {circle around (1)}, and the wireless communication control device 100 is notified.
[0049]
According to this, since the number of retries between the wireless communication control devices in the transfer route is accumulated and a route with few retries is selected, the use time is reduced when there are many transient communication abnormalities as in a wireless network. Thus, a path with relatively little abnormality can be selected, and data transfer can be performed stably.
[0050]
Also in the second embodiment, it is possible to modify the transfer route not by the transmission destination but by the transmission source. That is, a route response frame is transmitted from the wireless communication control device 120 to each of the routes (1) and (2) and received by the wireless communication control device 100. The number of retries of the route response frame is initialized with the number of retries accumulated in the route investigation frame as an initial value, and the number of retries generated on the return route is accumulated by each communication control device. The radio communication control apparatus 100 determines the transfer path that uses the one with the smaller number of retries in the received path response frame.
[0051]
In the example shown in the flow of FIG. 5, since no retry occurs in the transfer of the route investigation frame and the route response frame in the route {circle around (1)}, the value of the retry count 306 in the route response frame of the route {circle around (1)} is zero. On the other hand, the number of retries for the route investigation frame in route (2) is two, and the number of retries for the route response frame is one. Therefore, the value of the number of retries 306 in the route (2) route response frame is 3. As a result, the wireless communication control device 100 selects the route (1) as a route between the wireless communication control device 100 and the wireless communication control device 120.
[0052]
Example 3
Embodiment 3 of the transfer route control method is a method of determining a route having the smallest number of times load among a plurality of routes as a transfer route. Hereinafter, route check from the wireless communication control device 100 to the wireless communication control device 110 is performed. An example of transmitting a frame will be described. The route investigation frame applied to the third embodiment has the same format as the frame of FIG. That is, before the route investigation frame is transferred from the wireless communication control device 100 to the wireless communication control device 120, each wireless communication control device calculates the line load per unit time and uses the maximum value for the line load of the route investigation frame. 307 areas are updated.
[0053]
FIG. 8 shows a flow of transmission processing of the wireless communication control device including calculation of the line load. When the wireless communication control device receives the route investigation frame from the previous stage (s201), it checks the destination address 301 and CRC 305 of the route investigation frame (s202). If it is determined in the CRC 503 check that the path investigation frame has been normally received, the current line load with the next-stage radio communication control apparatus is calculated (s203).
[0054]
As an example of a method for calculating the line load, "the number of bits of frames transmitted / received to / from the next-stage radio communication control apparatus in the past one second" is divided by "the band of the line between the next-stage radio communication control apparatus". . For example, when the line bandwidth is 100 MBit / sec and the number of transmission bits to the next-stage wireless communication control device in the past 1 second is 64.8 Mbit / sec, the load is 0.648. This line load indicates the degree of occupation of the line bandwidth, and the band that can be transmitted and received at 100 MBit / sec can be transferred only 64.8 Mbit / sec for some reason. That is, the lower the line load value, the lower the throughput.
[0055]
After the line load is calculated, the value of the line load 307 in the received route investigation frame is compared with the calculated line load value (s204). If the calculated load is large, the value of the line load 307 in the route investigation frame is calculated. The calculated load is rewritten (s205), and a route investigation frame is transmitted to the radio communication control device at the next stage (s206). If the value of the line load 307 in the route check frame is larger than the calculated load, the value of the line load 307 in the route check frame is left as it is, and the route check frame is transmitted to the radio communication control device at the next stage.
[0056]
After transmitting the route investigation frame, the reception response from the next-stage radio communication control apparatus is monitored by the timer 201 in the radio communication control apparatus (s207). If the reception response is returned before the timer 201 times out, the transmission of the route investigation frame to the radio communication control device at the next stage is completed. On the other hand, if the reception response is not received before the timer 201 times out, the route investigation frame is transmitted again. Then, returning to step s203, the load is calculated again. The load calculation here is performed including the number of transmission bits of the route investigation frame transmitted to the next stage wireless communication control device. For this reason, the number of unnecessary transmission bits increases every time the transmission of the route investigation frame is retried, and the load value increases.
[0057]
As described above, the load is calculated until the transmission retry of the route investigation frame is successful, and the largest line load value is written in the area of the line load 307 of the route investigation frame. In the route survey frames transmitted to the route (1) and the route (2) in FIG. 6, the value of the line load 307 of the route survey frame that has passed the route (1) is the route (2) where the retry of the route survey frame occurs. Generally, it becomes smaller than the value of the line load 307 of the route investigation frame that has passed through. At this time, the wireless communication control device 120 compares the line load 307 of the route investigation frame that has passed the route (1) and the route (2), and the wireless communication control device 100 and the wireless communication control device 100 are wirelessly connected to the route (1) with a small value of the line load 307. It is determined that the route is between the communication control devices 120.
[0058]
By the way, when there is another wireless network close to the wireless network in FIG. 2 and the communication control device of the route {circle around (1)} shares the communication band with the wireless communication control device of the other network, Since both of the data that can be transmitted and received are limited by the arrival of the transmission signal, the throughput of the apparatus is reduced accordingly. According to the comparison of the line load of the present embodiment, it is possible to select a route with higher processing efficiency including such a load variation peculiar to the radio.
[0059]
Also in the third embodiment, it is possible to modify the transfer path at the transmission source. That is, a route response frame is transmitted from the wireless communication control device 120 to each of the routes (1) and (2) and received by the wireless communication control device 100. At this time, the line load 307 of the route response frame is initialized to the value in the route check frame, is calculated by each communication control device of the return route, is compared with the line load, and is updated to the maximum value.
[0060]
In the example shown in the flow of FIG. 5, the number of retries for route (1) and route (2) is 0 and 3, respectively. Therefore, if there are no other factors, the load on route (2) becomes large. The route (1) with a small load is determined as the transfer route.
[0061]
As described above, the route determination method at the start of data communication in the wireless network has been described in the first to third embodiments. In the first embodiment, the processing time for determining a line is the shortest. In the second embodiment, the processing time becomes longer as the number of retries is accumulated. However, it is possible to more accurately reflect the line status of the wireless network in which a transient abnormality is likely to occur, and the reliability is improved. In the third embodiment, the processing time becomes the longest in calculating the line load and determining the maximum value. However, since the line load reflects the line conditions peculiar to the wireless network, such as the number of retries and bandwidth congestion, it is possible to select the transfer path with the least abnormality and high throughput. There are few and reliability is high.
[0062]
In each of the above embodiments, a common format can be used for the route investigation frame. That is, an investigation parameter area is provided in the frame, and the number of retries or the line load is stored according to the parameter of the control program. In the case of Example 1, it becomes a dummy.
[0063]
Next, characteristics of the case where the transfer path is determined by the transmission source and the case where the transfer path is determined by the transmission destination will be described. In general, since the method of determining at the transmission source reflects the line status through the round trip of the route, the reliability of route determination is increased, but there are the following advantages and disadvantages.
[0064]
When the transmission source is determined, the transmission source can predetermine the number of route investigation frames to be transmitted, so that the upper limit of the number of route response frames to be returned is also known. On the other hand, when deciding at the transmission destination, it is not known how many route investigation frames are received. Therefore, in the second and third embodiments, it is necessary to have a sufficient time for determining the timing for performing the path comparison and a storage area for data for comparison. Therefore, the storage device can be made smaller if the transmission source is determined.
[0065]
On the other hand, when the transmission source is determined, the route frame reciprocates once for each route, whereas when the reception side determines, the route frame is returned only to the determined route, so one line is used at the time of reply. It becomes only. For this reason, when the receiving side makes the determination, the line usage amount of the route investigation frame can be reduced, and the line load can be reduced.
[0066]
[Second Embodiment]
Next, as a second embodiment of the present invention, a transfer path monitoring and control method performed in a wireless network between a transmission source and a transmission destination during transmission will be described. The wireless communication control device and the wireless network in the second embodiment are the same as those in FIGS. 1 and 2 used for the description of the first embodiment.
[0067]
In the second embodiment, the number of retries or the line load stored in the data frame being communicated is monitored, and when these exceed the abnormality detection threshold, abnormality is detected as a sign or occurrence of a line abnormality. Furthermore, when an abnormality is detected, a route investigation frame similar to that of the first embodiment is issued, and the transfer route to be used is determined again.
[0068]
FIG. 9 shows a wireless network in which a line abnormality has occurred during communication. The network configuration is the same as in FIG. In the state of FIG. 2, the path (2) between the radio communication control apparatus 100 and the radio communication control apparatus 110 is abnormal, and the path (1) is selected as the frame transfer path and data communication is performed. . From this state, it is assumed that the line abnormality of the route (2) is recovered and the line between the wireless communication control apparatus 130 and the wireless communication control apparatus 140 becomes abnormal. In this case, the frame {circle around (1)} which is the frame transfer path between the wireless communication control device 100 and the wireless communication control device 120 cannot transfer the frame normally.
[0069]
FIG. 10 shows a frame flow of the route (1) where an abnormality has occurred during communication. Since the line between the wireless communication control device 130 and the wireless communication control device 140 is unstable, a retry occurs when transferring a data frame and a response frame to the data frame. In this embodiment, the format shown in FIG. 3B or 3C is used for the data frame, and the retry count 306 or the line load 307 is monitored to detect a path abnormality of the line in use.
[0070]
That is, the data frame storing the number of retries 306 or the line load 307 is transferred from the wireless communication control apparatus 100 to the wireless communication control apparatus 120 according to the procedure indicated by the route (1) in FIG. Upon receiving the data frame, the wireless communication control device 120 reads the retry count 306 or the line load 307 in the data frame and determines whether the value is equal to or greater than the threshold (instead of “comparison determination” at the transmission destination in FIG. 6). If the threshold is exceeded, a path response frame is transmitted to the wireless communication control apparatus 100 to notify the radio communication control apparatus 100 of the occurrence of an abnormality or a sign. The line abnormality notification is returned, for example, with the number of retries 306 and the value of the line load 307 set to specific values indicating the occurrence of abnormality.
[0071]
As the threshold value, the number of retries or the line load value is set in the line abnormality detection threshold value storage unit 211 of FIG. It is desirable to set the level of a line abnormality or sign immediately before communication is interrupted as a threshold value.
[0072]
Further, detection of line abnormality may be performed at the transmission source. The flow of the data frame and the response frame at this time is the same as the procedure shown in the route (1) in FIG. In the case of route {circle around (1)}, the radio communication control apparatus 100 reads the value of the retry count 306 or the line load 307 in the route response frame, and if the value exceeds the threshold value, an abnormality has occurred in the route {circle around (1)}. Is detected.
[0073]
When the transmission destination or its own device detects a line abnormality in the route being used by the transmission destination or its own device, the transmission source wireless communication control device 100 temporarily suspends communication and transmits a route investigation frame to the routes (1) and (2). A normal route is examined by the transfer route control method described in the first embodiment, and as a result, route (1) is selected. The wireless communication control device 100 resumes the temporarily interrupted data communication using the route (1).
[0074]
When a line abnormality is detected and the ongoing communication has not been interrupted yet, the route investigation frame is transmitted only to the route (2) that is not used by the wireless communication control device 100 of the transmission source. You may make it determine the usability. Further, in the re-determination of the transfer route due to the abnormality detection during communication, the method of the first embodiment is preferably used to minimize the processing time until switching. However, when the reliability described above is taken into consideration, the method of the second embodiment or the third embodiment may be used.
[0075]
【The invention's effect】
According to the present invention, in a wireless network in which a transient abnormality is likely to occur, the line state is investigated for a plurality of routes from the transmission source to the transmission destination, the route having a good line state is determined, and data is transferred. Since the route is determined, stable wireless communication with less accident interruption can be realized, the reliability of the wireless network is improved, and the application to a large-scale network is enabled. Further, since the shortest processing time path or the minimum line load path can be selected, the data transfer processability can be improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a wireless communication control device according to an embodiment of the present invention.
FIG. 2 is a configuration diagram of a wireless network to which the present invention is applied.
FIG. 3 is a configuration diagram of a frame according to a plurality of embodiments used for wireless communication according to the present invention.
FIG. 4 is a flowchart (part 1) of a route investigation frame in a wireless network.
FIG. 5 is a flowchart (part 2) of a route investigation frame in the wireless network.
FIG. 6 is a flowchart of a route investigation frame in the wireless network (part 3).
7 is a flowchart showing a processing procedure of a retry count value in a route investigation frame by the wireless communication control device of FIG. 1;
8 is a flowchart showing processing of a line load value in a route investigation frame by the wireless communication control device of FIG.
FIG. 9 is an explanatory diagram showing an example of occurrence of a line abnormality in a wireless network during communication.
FIG. 10 is a flowchart of a data frame for detecting the occurrence of a line abnormality during communication.
[Explanation of symbols]
100, 110, 120, 130, 140 ... wireless communication control device, 101-103, 121-123 ... wireless terminal, 200 ... control unit, 201 ... timer, 202 ... demodulator, 203 ... bandpass filter, 204 ... reception mixer 205 ... frequency synthesizer, 206 ... transmission mixer, 207 ... modulator, 208 ... transmission / reception buffer, 209 ... antenna, 210 ... transmission / reception changeover switch, 211 ... line abnormality detection threshold storage unit, 300 ... preamble, 301 ... destination address, 302 ... Source address, 303 ... Route, 304 ... Data, 305 ... CRC, 306 ... Number of retries, 307 ... Line load.

Claims (4)

In a wireless network configured to have a plurality of paths for transmitting data from a communication control device serving as a transmission source to another communication control device serving as a transmission destination among a plurality of communication control devices having a wireless communication function.
A route in which route information can be investigated is transmitted from the transmission source to the transmission destination, and the route with the highest line quality among the routes or a plurality of routes in which the line quality is higher than a certain level according to the route information acquired through this frame A transfer route control function that determines the route to be used,
During communication from the transmission source to the transmission destination, using the route information area provided in the frame to acquire the route information on the route, compare the value of the abnormality detection threshold and the route information area at the transmission destination, When the value of the route information area exceeds the abnormality detection threshold, a line abnormality detection function for performing abnormality detection of a communication path and notifying the transmission source of an abnormality occurrence,
A wireless network provided in each of the plurality of communication control devices. 2. The transmission source according to claim 1, wherein when the transmission source learns the occurrence of an abnormality in the use route by the line abnormality detection function, the communication is temporarily suspended, and at least through all other routes outside the use route by the transfer route control function. A wireless network that transmits a frame in which the route information can be investigated to the transmission destination, and determines a use route based on the received route information. The communication control device according to claim 1, wherein the communication control device has an area for storing a line load in the path information checkable frame, and relays a route check frame from the transmission source to the transmission destination or a return route check frame. The current line load is obtained when the route investigation frame is transmitted to the communication control device of the next stage, and when the obtained line load is larger than the value of the line load stored in the route investigation frame, Rewrite the line load to the calculated line load, compare the line load in the route check frame received by the transmission destination or the transmission source from a plurality of routes, and determine the route with the lowest line load as the route with the best line quality A wireless network characterized by:   4. The line load according to claim 3, wherein the line load is calculated by calculating a bit number of a frame transmitted / received to / from a next-stage communication control apparatus from a present time to a predetermined time in a band of a line with the next-stage communication control apparatus. A wireless network characterized by being represented by a divided value.

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