JP3963153B2 - Wireless terminal, wireless communication method, and program for wireless communication network system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, for each communication, a plurality of wireless communication devices function as a transmitting device, a receiving device, or a relay device, and in one communication, data is transmitted directly or via one or more wireless communication devices that function as a relay device. The present invention relates to a wireless communication network system that performs transmission and reception.
[0002]
[Prior art]
Conventionally, a wireless communication network system having a configuration in which wireless communication is used as a communication path and a wireless packet transmitted from a transmitting terminal is relayed by one or a plurality of wireless devices and delivered to a receiving terminal. Various proposals have been made.
[0003]
For example, the invention described in Patent Document 1 is a system that performs wireless communication between a central base station connected to a wired network and each wireless base station. Wireless communication is performed by relaying a wireless base station between the central base station and a transmission destination wireless base station. When the average delay time between base stations changes greatly due to, for example, a change in the quality of the radio space, the radio base station that detects this change notifies the central base station. Upon receiving this notification, the central base station determines a new route based on the configuration information.
[0004]
Further, for example, in the invention described in Patent Document 2, in a wireless circuit network in which a plurality of nodes operate as a repeater, packets are randomly transmitted through all possible routes using all nodes in the circuit network as in the past. Rather than hop along a single pre-programmed path, a compact partial routing table is stored in the memory portion of each pre-selected node of the network. A plurality of predetermined communication paths are stored between the building computer and the destination node to improve the probability of successful data transmission between END and END and to realize high data transmission processing capability of the circuit network. It also eliminates the need to include all routing information in the data packet.
[0005]
Further, for example, in the invention described in Patent Document 3, in a method of determining a route by broadcasting a route determination packet before communication, conventionally, once a communication route is selected, circuit disconnection of the route is detected. Since this route is used, there is a problem that delay fluctuation occurs in the signal arrival time. However, after the main route is constructed, data transmission is started, and at the same time, a detour route is constructed.
[0006]
Further, in the invention described in the prior application (Patent Document 4) already proposed by the present applicant, the configuration information and reliability held by each wireless terminal in order to improve communication reliability and transmission distance. Based on the information, an optimum transfer route is determined and relay transfer is performed. In addition, when a packet environment is deteriorated due to the influence of disturbance or the like during relay transfer of a packet and packet transfer fails between relay terminals, the relay wireless terminal transmits the configuration information and reliability in the terminal. Based on the sex information, another route is selected and the route is dynamically changed to improve communication reliability.
[0007]
FIG. 16 is a diagram (part 1) for explaining the prior application and is a diagram illustrating an example of a network configuration.
FIG. 17 is a diagram (part 2) for explaining the prior application, and shows an example of configuration information held in each wireless terminal in the network configuration of FIG.
[0008]
The wireless communication network system of FIG. 16 includes 10 wireless terminals from wireless terminal A to wireless terminal J. Then, an arbitrary wireless terminal transmits a packet to an arbitrary wireless terminal. At this time, each wireless terminal other than the transmitting-side and destination-side wireless terminals functions as a relay terminal that relays / transfers this packet. Each wireless terminal holds configuration information, and based on this configuration information, determines a wireless terminal to which a packet is transferred, and relays / transfers the packet.
[0009]
FIGS. 17A to 17D show an example of this configuration information. Note that FIG. 17 shows only configuration information of some of the wireless terminals A to J, but other wireless terminals also hold configuration information.
[0010]
FIG. 17A shows an example of configuration information held by the wireless terminal A. FIG. 17B is an example of configuration information held by the wireless terminal B. FIG. 17C is an example of configuration information held by the wireless terminal E. FIG. 17D is an example of configuration information held by the wireless terminal G.
[0011]
Here, taking the configuration information of the wireless terminal A shown in FIG. 17A as an example, the shortest number of relay stages (number of communications) of packets from the wireless terminal A to each wireless terminal is first shown on the upper side. The wireless terminals B, C, and D having the communication count of 1 are wireless terminals that can directly communicate with the wireless terminal A. Therefore, the packet relay destination is selected from the wireless terminals B, C, and D. Furthermore, as shown in the lower side of the figure, the shortest number of relay stages of packets to each wireless terminal when these wireless terminals B, C, and D are selected as relay destinations is shown. Accordingly, for example, when a packet is transmitted from the wireless terminal A to the wireless terminal G, it is understood that the number of relay stages is the smallest when the wireless terminal B or C is selected as the relay destination.
[0012]
Although not specifically illustrated, each wireless terminal uses the communication path diagnosis packet to calculate the reliability value of the communication path with each wireless terminal that can directly communicate with its own device, thereby diagnosing the reliability of the communication path. is doing.
[0013]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-32073
[Patent Document 2]
Japanese National Patent Publication No. 11-504785
[Patent Document 3]
JP 2001-237875 A
[Patent Document 4]
JP 2000-13376 A
[0014]
[Problems to be solved by the invention]
In the invention described in the above-mentioned patent document 1, the radio terminal as a central base station collects error rates and the like in a concentrated manner to select a route, and selects the route by notifying the radio unit of the result and selecting the route. Therefore, the load on the central base station is large.
[0015]
The invention described in Patent Document 3 is not such that each relay terminal has the configuration information as in Patent Document 4, so that it is necessary to perform a process of determining the route by broadcasting the route determination packet before communication. In addition, extra processing is required in the stage before communication.
[0016]
On the other hand, in the method of the above-mentioned prior application (Patent Document 4), each wireless terminal holds configuration information, and a route for relaying and forwarding packets for each wireless terminal according to changes in the communication environment. Therefore, the processing load is distributed to each wireless terminal without burdening a specific device, and it is not necessary to include all routing information in the packet. It is possible to dynamically select the optimum route without having to perform the above.
[0017]
Here, in the wireless communication network of the above-mentioned prior application (Patent Document 4), for example, the amount of delay between END and END is less than or equal to a certain range, such as multimedia transmission (streaming system), control system transmission, and the like. Consider using an application that needs to fit within.
[0018]
In this case, in the method of the above-mentioned prior application (Patent Document 4), as described above, the relay transfer route dynamically changes according to the change in the communication environment, and thus the route with a large number of relays (detour) In some cases, the delay amount of each packet received at the final destination terminal may vary, and it is difficult to estimate the delay amount. For this reason, it is difficult to apply the wireless communication system of the above-mentioned prior application to an application in which the delay amount is required to be equal to or less than a certain amount or within a certain range. The same applies to the invention described in Patent Document 2.
[0019]
For example, in the example shown in FIG. 16, the route for transmitting packets from the wireless terminal J to the wireless terminal E is J → G → E (two-stage route), J → I → G → E, J → I → F → E (all three steps), J → I → H → F → E (four steps) can be taken. For this reason, the amount of delay at the receiving terminal varies depending on which route is taken. Furthermore, this is a simple example, and in fact, since a route with a larger number of relays (circular) can be taken, the variation in the delay amount further increases.
[0020]
In this way, it is required to reduce delay jitter (delay fluctuation and variation) .For example, if the communication path is fixed, the delay jitter can be reduced, but the communication environment in the wireless section changes dynamically, so disturbance When the environment of the communication path deteriorates due to the influence of the above, a problem arises in terms of reliability of communication quality of the network.
[0021]
An object of the present invention is to provide a wireless communication network system in which the amount of delay between END and END can be kept within a certain amount or within a certain range and the reliability of the communication quality of the network can be ensured. It is to provide a terminal and its communication method.
[0022]
[Means for Solving the Problems]
A wireless terminal according to the present invention includes a plurality of wireless terminals that perform wireless communication, and any of the wireless terminals can communicate with any other wireless terminal directly or via one or more other wireless terminals. Each wireless terminal that constitutes a wireless communication network system that can be used.
[0023]
Each wireless terminal includes configuration information storage means that stores information on the wireless terminal with which the device itself can communicate directly and configuration information that is information on the number of relays when communicating with other wireless terminals via the wireless terminal capable of direct communication And, based on the configuration information stored in the configuration information storage means, the wireless terminal with which the own device can directly communicate and the relay destination of the main route from among the wireless terminals on the shortest route to the receiving terminal Based on the configuration information stored in the configuration information storage unit and the main route determination unit that determines the terminal, the wireless terminal that can directly communicate with the own device, and the number of relays to the relay destination terminal of the main route Has a backup route determination means for determining a relay terminal for a backup route from wireless terminals that can be relayed twice, and relays and forwards packets using both the main route and the backup route. Configure to
[0024]
With the above configuration, since the packet is relayed using a plurality of routes, that is, both the main route and the backup route, the reliability of the communication quality of the network can be ensured. In addition, a certain condition is given to the determination method of the plurality of routes. That is, the main route is the shortest route to the receiving terminal, and the backup route is a relay destination terminal of the main route via a wireless terminal that can relay to the relay destination terminal of the main route with a relay count of two. The route to forward packets to. By defining the route determination method in this way, the delay amount between END and END can be made to be within a certain amount or within a certain range.
[0025]
In addition, for example, the configuration information further includes a reliability value indicating the reliability of a communication path with a wireless terminal with which the device itself can directly communicate, and the main route determination unit and the backup route determination unit include the reliability information. A wireless terminal having a high property value may be determined as a relay destination terminal for the main route and a relay terminal for the backup route.
[0026]
In this way, the reliability of communication quality can be improved by using a highly reliable communication path for both the main path and the backup path as a packet transfer path.
In addition, as described above, the reliability of the communication quality of the network can be ensured by using a plurality of routes, and the determined route can be used in a fixed manner. When it becomes impossible to ensure the reliability, the reliability of the communication quality of the network can be ensured by changing the route as described below.
[0027]
That is, the wireless terminal further includes a route change determination unit that determines whether or not to change the main route and the backup route determined by the main route determination unit and the backup route determination unit, and the route determination unit performs main processing. When it is determined that the route and the backup route are to be changed, the main route determination unit and the backup route determination unit determine a new main route and a backup route.
[0028]
The determination method by the route change determination means is, for example, as follows at the transmitting terminal.
That is, the route determined by the main route determining unit and the backup route determining unit is fixedly used during an arbitrary communication period, and the receiving terminal tabulates the packet arrival rate during the arbitrary communication period, The totaling result is returned to the transmitting terminal, and the route change determining means in the wireless terminal as the transmitting terminal performs the determination based on the incoming rate totaling result and a threshold value registered in advance. For example, if the incoming rate is equal to or less than the threshold, it is determined that the route should be changed.
[0029]
It is noted that the program may be read out and executed by a computer from a computer-readable storage medium storing a program for causing the computer to perform the same control as the function performed by each configuration of the present invention described above. Can solve the problem.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a functional block diagram of each wireless terminal constituting the wireless communication network system according to this example.
[0031]
Each wireless terminal of this example basically has substantially the same function as the wireless terminal of the earlier application, but the way of determining and changing the route is different. Another difference is that the route once determined is used fixedly for a predetermined period.
[0032]
The illustrated wireless terminal 10 includes a main route determination unit 11, a backup route determination unit 12, a route change determination unit 13, and a configuration information storage unit 14. For each communication, each wireless terminal 10 is either a transmission terminal that is a transmission source terminal that transmits an arbitrary wireless packet, a relay terminal that relays this wireless packet, or a receiving terminal that is the destination of this wireless packet. However, the configuration itself is the same. However, each functional unit shown in the figure shows a configuration necessary when functioning as a transmission terminal or a relay terminal. Further, the route change determination unit 13 has different processing methods depending on whether it is a transmission terminal or a relay terminal.
[0033]
In the following description, a wireless packet is simply referred to as a packet.
In the wireless communication network system according to this example, each wireless terminal has a configuration information storage unit 14 that stores configuration information as shown in FIG. The configuration information is roughly information on a wireless terminal with which the own device can directly communicate, and information on the number of relays when communicating with another wireless terminal via the wireless terminal capable of direct communication. Although not specifically shown in FIG. 17, information on reliability values calculated in the above-mentioned prior application is also included.
[0034]
Based on the configuration information stored in the configuration information storage unit 14, the main route determination unit 11 selects another radio terminal 10 on the shortest route to the receiving terminal that has a high reliability value. A relay destination terminal on the main route (hereinafter referred to as a main route relay destination terminal) is assumed (step S1 in FIG. 2).
[0035]
Based on the configuration information stored in the configuration information storage unit 14, the backup route determination unit 12 is another wireless terminal 10 that has two relay stages with respect to the main route relay destination terminal. A relay terminal having a high property value is used as a relay terminal for a backup path (hereinafter referred to as a backup path relay destination terminal) (step S2 in FIG. 2).
[0036]
Of course, the relay terminal selected in steps S1 and S2 is selected from wireless terminals with which the own apparatus can directly communicate.
The wireless terminal 10 functioning as a transmission terminal or a relay terminal determines the next relay destination terminal for transmitting the packet to the destination terminal, but also determines a backup route for the relay destination terminal. At that time, the main route relay destination terminal is always selected from the wireless terminals 10 on the shortest route to the receiving terminal. Furthermore, a packet is transmitted to the main route relay destination terminal via a route having two relay stages with respect to the main route relay destination terminal, that is, any other wireless terminal 10 (the backup route relay destination terminal). A route to be transmitted is determined as a backup route.
[0037]
As a result, the delay amount of communication between END and END, that is, between the transmitting terminal and the receiving terminal is always (main-route relay time) × 3 or less, as will be described in detail later. More specifically, it falls within the range of “relay time of main route” to “(relay time of main route) × 3”. Therefore, the delay amount between END and END can be set to be within a certain amount or within a certain range.
[0038]
Further, the route determined as described above is fixedly used during an arbitrary communication period. The receiving terminal counts the packet arrival rate in an arbitrary communication period, and returns the counting result to the transmitting terminal.
[0039]
The route change determination unit 13 of the calling terminal determines whether or not to change the route based on the result of the incoming call rate aggregation. If it is determined that the route is to be changed, the main route determination unit 11 and the backup route determination unit 12 perform basically the same processing as described above to determine a new main route and backup route. However, the currently used route is basically excluded, and a new main route and backup route are determined from routes other than the currently used route.
[0040]
In addition, the transmission terminal assigns a route identification number to each determined route, and transmits this by including it in a packet. The route change determination unit 13 of each relay terminal determines whether or not to change the route based on the identification number of this route. This point is different from the route change determination unit 13 of the transmission terminal.
[0041]
Hereinafter, the operation of the wireless communication network system and each wireless terminal will be described in more detail with reference to FIG.
FIG. 3 is a flowchart of processing for determining an initial route.
[0042]
11 to 13 are flowcharts of processing relating to path change.
First, the initial route determination process will be described with reference to FIG.
First, FIG. 3 shows a case where a packet is transmitted from an arbitrary wireless terminal 10 (transmitting terminal) to an arbitrary wireless terminal 10 (receiving terminal), and the transmission path between the wireless terminals has not yet been determined. Process. If the transmission path between the wireless terminals has already been determined, transmission is performed using the determined path, or if the path needs to be changed, the process of FIG. 13 described later is performed. To re-determine the route.
[0043]
The process of FIG. 3 will be described with reference to specific examples shown in FIGS.
First, FIG. 4 shows a simple specific example of the configuration of the wireless communication network system.
In the example of the illustrated wireless communication network system, there are six wireless terminals 10 (1) to (6). In this example, the wireless terminal (1) sends a packet to the wireless terminal (6) (hereinafter referred to as a transmitting terminal (1) and a receiving terminal (6)). Therefore, at least one of the wireless terminals 10 of (2) to (5) other than these functions as a relay terminal that relays a packet.
[0044]
The processing shown in FIG. 3 is executed at the calling terminal (1) and each relay terminal. Here, taking the case where the calling terminal (1) performs the processing of FIG. 3 as an example, FIG. 5 shows an example of the configuration information table held by the calling terminal (1), and FIG. 6 shows the creation and holding of the calling terminal (1). An example of a management table is shown.
[0045]
In FIG. 3, first, the calling terminal {circle around (1)} refers to the configuration information table 20 of FIG. The wireless terminal 10 having the smallest number of relay stages and having the highest reliability value is selected as the main route relay destination terminal (step S11).
[0046]
Subsequently, the configuration information table 20 is searched for another wireless terminal 10 that can relay the main route relay destination terminal selected in step S11 with two relay stages (step S12). As a result, if there is no wireless terminal 10 capable of relaying with two relay stages with respect to the main route relay destination terminal (step S13, NO), the main route relay destination terminal It is also assumed that it is also a backup route relay destination terminal (step S15). On the other hand, if there are one or more wireless terminals 10 that can be relayed with two relay stages (step S13, YES), the wireless terminal 10 having the highest reliability value is selected as a spare. It selects as a route relay destination terminal (step S14). Of course, if there is only one, the wireless terminal 10 is selected as the backup route relay destination terminal regardless of the reliability value.
[0047]
Finally, an arbitrary route number is assigned to the set of the main route relay destination terminal and the backup route relay destination terminal selected by the above processing, and the information is stored in the management table 30 together with the information of the calling terminal and the called terminal ( Step S16). As shown in FIG. 6, the management table 30 includes data items of a route number 31, a transmission terminal 32, a reception terminal 33, a main route relay destination terminal 34, and a backup route relay destination terminal 35. In the above example, since the wireless terminal (1) sends a wireless packet to the wireless terminal (6), (1) is stored in the calling terminal 32 and (2) is stored in the receiving terminal 33. When the configuration information table 20 is the example of FIG. 5, as a result of the processing described below, (4) is stored in the main route relay destination terminal 34 and (2) is stored in the backup route relay destination terminal 35. Will be. Here, it is assumed that “1” is assigned to the route number 31.
[0048]
In each relay destination terminal, the processing of FIG. 3 is executed in the same manner as the transmission terminal, but the route number 31 stored in the management table 30 in step S16 is the same value as the value determined by the transmission terminal. . As will be described later with reference to FIG. 7, the transmission terminal includes the route number data in the header of the packet transmitted to the relay destination terminal, so that the relay terminal can know the route number. In the relay terminal, the route number 31 is used when a route change is determined later.
[0049]
Here, an example of the configuration information table 20 in FIG. 5 will be described.
In the configuration information table 20, relay destination terminals No. 21 and 24 are wireless terminals that can directly communicate with the wireless terminal {circle around (1)}, and reliability values 23 and 26 correspond to the wireless terminal {circle around (1)} and these relays. This is a value indicating the reliability of the communication path between the previous terminals NO. The relay stage number 22 to the destination station indicates the shortest relay stage number until the packet reaches the destination terminal (6), which is the final destination terminal, when each relay destination terminal No. 21 is the next relay destination.
[0050]
The processing in step S11 is determined with reference to the number 22 of relay stages to the target station. In this example, since the relay destination terminal having the smallest number of relay stages to the receiving terminal {circle around (6)} is only the relay terminal {circle around (4)} having the relay stage number “2”, the relay is performed in step S11 regardless of the reliability value. The terminal {circle around (4)} is selected, but if there is another relay terminal having a relay stage number of “2”, the terminal with the highest reliability value is selected.
[0051]
The number of relay stages 25 to the target station is determined by regarding each relay destination terminal NO.24 by regarding the relay destination terminal selected in the process of step S11 as a virtual final destination terminal in the relay destination terminal NO.21. Represents the shortest number of relay stages until the packet reaches the virtual final destination terminal.
[0052]
In the processing of steps S12 and S13, it is determined whether or not there is a relay terminal having two relay stages with reference to the relay stage number 25 to the target station. In the example of FIG. 5, the relay terminals whose value of the relay stage number 25 to the target station is “2” are the relay terminals {circle around (2)} and {circle around (3)}, so the determination in step S13 is YES. Since the reliability value 26 of the relay terminal (2) is “75” and the reliability value 26 of the relay terminal (3) is “70”, the relay terminal (2) is selected in step S14. .
[0053]
The configuration information table 20 in FIG. 5 is configuration information of an earlier application such as the example shown in FIG. That is, the wireless terminal of this example holds configuration information similar to that of the previous application. The configuration information table 20 of FIG. 5 merely shows this configuration information in a format that makes this description easy to understand, and the content is the same as the configuration information of the prior application. For example, the relay destination terminals No. 21 and 24 in the configuration information table 20 of FIG. 5 are wireless terminals with which the wireless terminal can directly communicate as described above. For example, in the example of FIG. This corresponds to the wireless terminals of the first time, that is, the wireless terminals B, C and D. Assuming that the receiving terminal is H, the relay stage number 22 to the target station of each of the wireless terminals B, C, and D is “3”, “2”, and “2”. Furthermore, if the wireless terminal D is selected as the relay destination terminal of the main route, the number of communications from the wireless terminals B and C to the wireless terminal D is “2” and “1”. It can be seen that the value of the number of relay stages 25 to the target station of each of the wireless terminals B and C as the target terminal is “3” and “2”.
Further, in the prior application, the reliability value of the communication path between each wireless terminal with which the device itself can directly communicate is calculated using the communication path diagnosis packet. A value is calculated and stored in the reliability values 23 and 26.
[0054]
Using the various information determined by the processing described above, the transmitting terminal (1) transmits a packet including header information shown in FIG. 7, for example. Of course, the header configuration of the packet transmitted by each relay destination terminal is the same.
[0055]
FIG. 7 is a configuration diagram of a packet header.
In the header 40 of the illustrated packet, the transmission source ID 41 is an identification ID of the transmission terminal. Each wireless terminal 10 is assigned a unique identification ID in advance. In the above example, the transmission source ID 41 is the identification ID of the transmission terminal (1).
[0056]
The incoming call source ID 42 is an identification ID of the incoming call terminal that is the final destination terminal of the packet. In the above example, this is the identification ID of the receiving terminal (6).
The relay ID 43 is an identification ID of the main route relay destination terminal. In the above example, the identification ID is the relay terminal (4).
[0057]
The spare ID 44 is an identification ID of the spare route relay destination terminal. In the above example, the identification ID is the relay terminal (2).
The route number 45 is the value of the route number 31 in the management table 30.
[0058]
The main / spare code 46 is a code, a flag, or the like indicating whether the packet is a main route packet or a backup route packet. Here, it is assumed that a flag “1” is stored when the packet is for the main route, and a flag “0” is stored when the packet is for the backup route. As will be described later, the transmission terminal and the relay terminal sequentially transmit a main route packet and a backup route packet. The spare ID 44 is stored only in the packet for the spare route.
[0059]
Each wireless terminal 10 receiving this packet captures this packet when the main / standby code 46 is “1” and the relay ID 43 is the identification ID of its own device. Transfer to the next relay destination terminal. Of course, the transfer route has two routes, a main route and a backup route. If the relay destination terminal has not yet been determined, the processing of FIG. 3 is executed as in the case of the transmission terminal, the next relay destination terminal and its backup route are determined, and this packet is relayed. To do.
[0060]
On the other hand, the wireless terminal 10 that has received a packet in which the main / spare code 46 is “0” and the spare ID 44 is the identification ID of its own device transfers this packet to the wireless terminal having the relay ID 43, that is, the main route relay destination terminal. . At this time, the main / spare code 46 is changed to “1” and the spare ID 44 is deleted. That is, the packet is transferred to the main route packet configuration.
[0061]
When the main route relay destination terminal normally receives the packet for the main route, the main route relay destination terminal immediately executes a process for transferring the packet to the next relay destination terminal. Even if the same packet transferred via is received, it is discarded.
[0062]
By the initial route determination process described above, for example, a main route and a backup route as shown in FIG. 8 are determined. According to the above example, as shown in FIG. 8, the packet is transmitted in two stages from the transmission terminal (1) to the relay terminal (4) via the main route for direct packet transmission and the relay terminal (2). A backup route is determined. Also, in the relay terminal (4) that has received this packet, the processing of FIG. 3 is performed in the same manner as the originating terminal (1). As a result, for example, as shown in FIG. Assume that a main route for direct packet transmission and a backup route for transmission via the relay terminal (5) are determined.
[0063]
As shown in the figure, the packet transmission path from the transmission terminal (1) to the relay terminal (4) has one stage for the main path and two stages for the backup path. The same applies to the packet transmission path from the relay terminal (4) to the receiving terminal (6). Further, since the figure shows a simple network configuration, the packet arrives immediately from the relay terminal (4) to the receiving terminal (6). However, in an actual more complicated wireless communication network, the relay terminal is usually used. It will be relayed from (4) to another relay terminal and relayed from this relay terminal to another relay terminal, and the same relay process should be repeated many times, but no matter how complicated it will be, The packet transmission path from one wireless terminal 10 to the wireless terminal 10 that is the next relay destination terminal always has one stage for the main path and two stages for the backup path, and the same process is repeated until it reaches the receiving terminal. It is.
[0064]
For example, in the case of packet transmission from the transmission terminal (1) to the relay terminal (4), as shown in FIG. 9, the time required for packet transmission from the transmission terminal (1) to the relay terminal (4) is always 1 slot for main path transmission and 2 slots for backup path transmission are fixed to a total of 3 slots. The same thing is repeated at each relay destination terminal.
Therefore, if the packet transmission time when packet transmission is performed on the main route is T, the packet transmission time when packet transmission is performed on the backup route is 3T, and the packet transmission time is always It is guaranteed to be in the range of T-3T. Further, as described above, since the main route is always the shortest route to the receiving terminal, the value of T is substantially constant.
[0065]
As described above, if a wireless terminal having the above configuration is used, by providing a plurality of routes, even if a problem occurs in one route due to changes in the communication environment, communication can be performed on the other route. The reliability of network communication quality can be ensured. In addition, the plurality of routes always have one of them as the shortest route to the receiving terminal and the other as a route that relays to each wireless terminal on the shortest route with the number of times of relaying twice. Can be defined to fall within a predetermined range. Therefore, the delay amount between END and END can be kept within a certain amount or within a certain range, and the reliability of the communication quality of the network can be secured, so that the delay amount is within a certain amount or within a certain range. This is suitable when using an application that needs to fit.
[0066]
Furthermore, if the communication environment deteriorates, etc., even if multiple routes are used, it becomes impossible to ensure the reliability of communication quality, so the network can be changed by changing the route as described below. The reliability of communication quality can be secured.
[0067]
Hereinafter, the route changing process will be described.
The route (main route, backup route) determined by the above-described processing is used fixedly during a predetermined transfer period. As shown in FIG. 10, the receiving terminal obtains the incoming rate of packets received during this transfer period, and sends this incoming rate information to the transmitting terminal.
[0068]
The transmitting terminal that has received the incoming rate information compares the incoming rate information with a predetermined threshold as shown in FIG. 11 (step S21). The threshold is determined in advance as an incoming rate that can be accepted by the system, and is registered in all wireless terminals. In addition, even if there is a packet that does not reach the receiving terminal, the transmitting terminal does not perform retransmission. That is, in the wireless communication network of this example, connectionless communication such as UDP is performed.
[0069]
If the incoming call rate is not less than or equal to the threshold value (step S22, NO), communication is performed with the current route.
If the incoming rate is equal to or less than the threshold (step S22, YES), it is determined that the route needs to be changed, and the route re-search process is performed (step S23). Details of the processing in step S23 are shown in FIG. 13 and will be described in detail later.
[0070]
In addition, when the transmission terminal changes the route, each relay terminal also performs route re-search processing. Each relay terminal determines whether the route should be changed as shown in FIG. The determination is made based on the route number 31 of the management table 30 held by itself and the route number 45 of the received packet.
[0071]
That is, as described above, the transmitting terminal assigns an arbitrary route number to the route determined by itself and transmits this as the route number 45 of the packet. However, when the route is changed by the process of step S23, Gives a new route number to this route, records it in the management table 30, and transmits the new route number in a packet. Thereby, each relay terminal can determine whether or not the route has been changed by referring to the route number.
[0072]
That is, each time a packet is received, each relay terminal uses the transmission source ID 41 and the reception source ID 42 to search the management table 30 for a record in which the transmission terminal 32 and the reception terminal 33 match, and if they match, If the record does not exist, the initial route determination process of FIG. 3 is executed. If there is a matching record, the route number 31 is referred to and whether or not this matches the route number 45 of the packet. Is determined (steps S31 and S32).
[0073]
If the route numbers match (step S32, YES), the current route remains unchanged. That is, the packet is transferred through the route stored in the main route relay destination terminal 34 and the backup route relay destination terminal 35 of the record.
[0074]
On the other hand, if the route numbers do not match (step S32, NO), it is determined that the route needs to be changed, and a route re-search process is performed (step S33). The route re-search process itself is the same as the process in step S23 of the transmitting terminal, and FIG. 13 shows the details thereof.
[0075]
FIG. 13 is a detailed flowchart of the route re-search process in step S23 or S33.
In FIG. 13, the calling terminal or the relay terminal refers to the configuration information table 20 in FIG. 4 held by the own device, and has the smallest number of relay stages to the receiving terminal among the wireless terminals with which the own device can directly communicate. It is determined whether there is a wireless terminal that has the next highest reliability value next to the relay destination terminal of the main route selected last time (steps S41 and S42). YES), this relay terminal is selected as the main route relay destination terminal (step S43). The main route relay destination terminal selected last time is stored in the main route relay destination terminal 34 of the management table 30.
Subsequently, for the main route relay destination terminal selected in step S43, the configuration information table 20 is searched for a relay terminal that can be relayed with two relay stages and has the highest reliability value. Obtained (step S44). As a result, if there is no relay terminal capable of relaying with two relay stages with respect to the main route relay destination terminal (step S45, NO), the main route relay destination terminal It is also assumed that it is a route relay destination terminal (step S47). On the other hand, if there is one or more relay terminals that can be relayed to the main route relay destination terminal with two relay stages (YES in step S45), the reliability value is the highest among these relay terminals. The higher one is selected as the backup route relay destination terminal (step S46). Of course, if there is only one, the relay terminal is selected as a backup route relay destination terminal regardless of the reliability value.
[0076]
On the other hand, if the determination in step S42 is NO, the previously selected main route relay destination terminal, that is, the relay terminal stored in the main route relay destination terminal 34 of the management table 30, is again connected to the main route relay. Select as a destination terminal (step S48).
[0077]
Subsequently, for the main route relay destination terminal selected in step S48, the relay terminal is capable of relaying with two relay stages and has the next highest reliability value after the previously selected backup route relay destination terminal. Is obtained by searching the configuration information table 20 (step S49). The protection route relay destination terminal selected last time is stored in the protection route relay destination terminal 35 of the management table 30.
[0078]
As a result of the processing in step S49, if there is no relay terminal capable of relaying with the number of relay stages of 2 for the main route relay destination terminal other than the previously selected backup route relay destination terminal (step S49) (S50, NO), the previously selected backup route relay destination terminal is selected again as the backup route relay destination terminal (step S52).
[0079]
On the other hand, if there is one or more relay terminals that can relay to the main route relay destination terminal with two relay stages other than the previously selected backup route relay destination terminal (step S50, YES), The relay terminal whose sex value is the next higher than the backup route relay destination terminal selected last time is selected as the backup route relay destination terminal (step S51).
[0080]
Finally, the main route relay destination terminal and the backup route relay destination terminal 35 of the management table 30 are updated and the route number 31 is updated by the main route relay destination terminal and the backup route relay destination terminal selected by the above processing. (Step S53). The route number 31 is updated using a newly determined route number at the transmitting terminal, and the route number 45 of the received packet at each relay terminal.
[0081]
If the route change process described above is described with respect to the examples of FIGS. 5, 6 and 8, when the process of FIG. 13 is executed at the calling terminal (1), the incoming call is received in the example of the configuration information table 20 shown in FIG. Since the relay terminal having the minimum number of relay stages to the terminal {circle around (6)}, that is, the second stage is only the relay terminal {circle around (4)}, the determination in step S42 is NO, and the relay terminal is again used as the main route relay destination terminal 4 ▼ will be selected. Further, in the determinations in steps S49 and S50, the terminal whose relay stage number 25 to the target station in the configuration information table 20 is “2” is not the relay terminal {circle around (2)} which is the previous backup route relay destination terminal. Since there is a relay terminal (3), the determination in step S50 is YES, and this relay terminal (3) is set as a new backup route relay destination terminal.
[0082]
As a result, as shown in FIG. 14, the main route is not changed, but the backup route is changed to the route via the relay terminal (3). The relay terminal (4), which is the main route relay destination terminal, similarly performs the processing of FIG. 13. However, since only one route exists as shown in the figure for both the main route and the backup route, the route is changed. Not.
[0083]
The examples shown in FIGS. 8 and 14 and the like show a very simple configuration example for ease of explanation. In practice, there are usually a plurality of routes for both the main route and the backup route. Can do. For example, the example shown in FIG. 16 is also a simple example, but when a packet is transmitted from the wireless terminal D to the wireless terminal G, the route that can be the main route, that is, the shortest route to the receiving terminal is D → C → E. → G, D → F → E → G, D → F → I → G.
[0084]
Finally, FIG. 15 shows a schematic diagram of the hardware configuration of the wireless terminal 10. This shows only the parts relevant to this description.
The illustrated wireless terminal 10 includes a CPU (MPU) 51, a memory 52, a wireless function unit 53, an antenna 54, and the like.
[0085]
The memory 52 stores a configuration information table 20, a management table 30, and the like. The memory 52 also stores a program for realizing the processing shown in FIGS. 2, 3, and 11 to 13 in the wireless terminal 10, and the CPU (MPU) 51 reads and executes this program. , Perform these processes.
[0086]
The wireless terminal 10 that can execute a predetermined process by executing a predetermined program in this way can be regarded as a kind of computer.
The program may be stored in advance in the memory of the wireless terminal 10, or may be downloaded from the outside, or the wireless terminal 10 may be a portable recording medium such as a memory card. May be configured to read and execute the program from a portable recording medium on which the program is recorded. That is, the present invention can be configured as a portable storage medium itself that records a program for realizing the various processes according to the present invention on a computer, or as the program itself.
[0087]
【The invention's effect】
As described above in detail, according to the wireless communication network system, the wireless terminal, the wireless communication method, and the program of the present invention, the delay between END and END particularly in the wireless communication network system as in the prior application. Use applications where the amount can be kept below a certain amount or within a certain range and the reliability of network communication quality can be ensured, so that the amount of delay must be below a certain amount or within a certain range This is suitable for the case.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of each wireless terminal constituting a wireless communication network system according to the present example.
FIG. 2 is a schematic flowchart of relay destination determination processing by each wireless terminal.
FIG. 3 is a flowchart of processing for determining an initial route.
FIG. 4 is a diagram showing a simple specific example of the configuration of a wireless communication network system.
FIG. 5 is a diagram showing an example of a configuration information table held by a calling terminal (1).
FIG. 6 is a diagram showing an example of a management table created and held by the calling terminal (1).
FIG. 7 is a configuration diagram of a header of a packet.
8 is a diagram showing a main route and a backup route determined according to the examples of FIGS. 4 and 5. FIG.
FIG. 9 is a diagram for explaining that the delay amount is equal to or less than a certain amount or within a certain range.
FIG. 10 is a diagram illustrating timings of packet transmission and incoming rate information return.
FIG. 11 is an overall flowchart of a route change process at a calling terminal.
FIG. 12 is an overall flowchart of route change processing in each relay terminal.
13 is a detailed flowchart of step S23 in FIG. 11 and step S33 in FIG.
FIG. 14 is a diagram showing a main route and a backup route after change.
FIG. 15 is a hardware configuration diagram of a wireless terminal.
FIG. 16 is a diagram for explaining an earlier application (part 1) and illustrates an example of a network configuration;
FIG. 17 is a diagram (part 2) for explaining the prior application, and is a diagram illustrating an example of configuration information held by each wireless terminal;
[Explanation of symbols]
10 Wireless terminal
11 Main route determination unit
12 Preliminary route determination unit
13 Route change determination unit
14 Configuration information storage unit
20 Configuration information table
21 Relay destination terminal No.
22 Number of relay stations to target station
23 Reliability values
24 Relay destination terminal No.
25 Number of relay stations to target station
26 Reliability values
30 Management table
31 Route number
32 Calling terminal
33 Incoming terminal
34 Main route relay destination terminal
35 Backup route relay destination terminal
40 packet header
41 Sender ID
42 Caller ID
43 Relay ID
44 Spare ID
45 Route number
46 Main / spare code
51 CPU (MPU)
52 memory
53 Wireless Function Unit
54 Antenna

Claims (6)

The wireless communication network system includes a plurality of wireless terminals that perform wireless communication, and any of the wireless terminals can communicate with any other wireless terminal directly or via one or more other wireless terminals. In each wireless terminal
Configuration information storage means for storing configuration information that is information on the number of relays when communicating with other wireless terminals via the wireless terminal that can communicate directly with the information of the wireless terminal that the device itself can communicate with,
Based on the configuration information stored in the configuration information storage means, the relay terminal of the main route is selected from the wireless terminals that can directly communicate with the own device and are on the shortest route to the receiving terminal. A main route determination means to determine;
Based on the configuration information stored in the configuration information storage means, a wireless terminal that can directly communicate with its own device and that can relay to the relay destination terminal of the main route with a relay count of 2 And a backup route determining means for determining a relay terminal for the backup route,
A wireless terminal of a wireless communication network system that relays and forwards a packet using both the main route and the backup route. A route change determination unit for determining whether to change the main route and the backup route determined by the main route determination unit and the backup route determination unit;
The main route determination unit and the backup route determination unit determine a new main route and backup route when it is determined by the route determination unit that the main route and backup route are to be changed. The wireless terminal of the wireless communication network system according to claim 1. The configuration information further includes a reliability value indicating the reliability of the communication path with the wireless terminal with which the device itself can directly communicate,
2. The main route determining unit and the backup route determining unit determine a radio terminal having a high reliability value as a relay destination terminal of the main route and a relay terminal for the backup route, respectively. A wireless terminal of the wireless communication network system according to 2. The route determined by the main route determination unit and the backup route determination unit is used fixedly during an arbitrary communication period,
The receiving terminal tabulates the packet arrival rate during the arbitrary communication period, and returns the summation result to the calling terminal,
4. The route change determination means in the wireless terminal that is the transmitting terminal performs the determination based on the incoming rate totalization result and a threshold value registered in advance. Wireless terminal for wireless communication network system. The wireless communication network system includes a plurality of wireless terminals that perform wireless communication, and any of the wireless terminals can communicate with any other wireless terminal directly or through one or more other wireless terminals. A wireless communication method in each wireless terminal,
Stores configuration information, which is information on the number of relays when communicating with other wireless terminals via the wireless terminal that can directly communicate with the information of the wireless terminal that the device itself can communicate with,
Based on the configuration information, a wireless terminal with which the own device can directly communicate and determines a relay destination terminal of the main route from wireless terminals on the shortest route to the receiving terminal, and the own device directly Determining a relay terminal for a backup route from wireless terminals that can communicate and relay to the relay destination terminal of the main route with a relay count of 2;
A wireless communication method characterized in that a packet is relayed and transferred using both the main route and the backup route. On the computer,
Based on the configuration information, the function of storing the configuration information that is information of the wireless terminal that can be directly communicated with itself and the information on the number of relays when communicating with other wireless terminals via the wireless terminal that can be directly communicated, A wireless terminal capable of directly communicating with the own device, and determining a relay destination terminal of a main route from among wireless terminals on a shortest route to a receiving terminal, and capable of directly communicating with the own device A function of determining a relay terminal for a backup route from wireless terminals that can relay the relay destination terminal of the main route in two times;
A function of relaying / forwarding packets using both the main route and the backup route;
A program to realize

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