JPH1132073A - Radio packet path determination method in radio network - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for determining an optimum radio network path for performing bidirectional communication between radio base stations. SOLUTION: Respective radio base stations 2-1 to 2-5 record information for calculating an optimum path as measured information, and when the measured information changes and a radio packet to central base stations 1-1 and 1-2 exists, the information is added to that radio packet. However, when such a radio packet does not exist, there is only the measured information at a repeater station. If a radio packet between the other central base stations 1-1 and 1-2 exists, the measured information is described and transmitted. At the central base station, the measured information is extracted and preserved, and if transmitting the optimum path to the respective radio base stations 2-1 and 202 towards these radio base stations and a radio packet to be transmitted to the relevant route exists, the optimum path is added and transmitted to that radio packet. However, when such a radio packet does not exist, only the optimum path is transmitted and the respective radio base stations 2-1 to 2-5 are constituted, so as to determine the optimum path by extracting that path from the radio packet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio network for performing two-way communication between radio base stations. The present invention relates to a method for dynamically, autonomously distributing, and efficiently setting a route.

[0002]

2. Description of the Related Art In a network having a plurality of radio base stations, there are two methods for determining a route of a radio packet between the radio base stations. One is a method in which each wireless base station independently determines a route to a target wireless base station for transmitting a wireless packet, and the other is a method in which a wireless base station managing a route determines a route, or Is provided, and each wireless base station determines a route based on the information.

In the former method, the method for determining a route is further divided into two. One is a method in which each wireless base station records a route to a wireless base station of a transmission destination as a route information table and transmits wireless packets according to the route information table (document: JOHN JUBIN, et al, "The DARPA Packet Radio
Network Protocols, "Proc. Of The IEEE, vol 75, No1,
Jan. 1987).

[0004] When a route is changed due to a change in a radio space or the like, an optimum route is always maintained by independently and simultaneously transmitting a route information table held by each radio base station. The route information describes the next wireless base station to be transmitted and the number of relays (the number of hops) in order to transmit a wireless packet to the target wireless base station. The route is determined so that the number of hops is reduced as much as possible. Is done.

As another method for determining an optimal route, geographic information is recorded in each radio base station,
There is a method of determining a route based on the geographic information (US Pat. No. 4,939,726). In this method, a route is determined based on geographical information such as the latitude and longitude of a target wireless base station. The wireless base station that has received the wireless packet relays the wireless packet so as to be closer to the target wireless base station.

In the method in which each radio base station determines a route based on information of the radio base station that manages the route, the radio base station (central base station) that manages the route first transmits a signal for determining an optimal route to the surroundings. The broadcast is transmitted to the radio base station simultaneously. Each radio base station receiving this signal returns a signal to the central base station. Each radio base station sets the route that the signal arriving first from the central base station has passed as the optimal route,
The central base station determines an optimal route to each wireless base station from the route of the returned signal.

[0007]

Among the conventional route determination methods, the former method of directly transmitting a wireless packet on an optimal route includes a method of determining a route based on a route information table. The size of the route information table also increases as the number of packets increases, and when the route is further changed, the route information table is broadcasted from each wireless base station to change the route information. . This leads to a decrease in the use efficiency of the wireless section.

In the method of recording geographic information in a radio base station, it is necessary to update geographic information every time the position of the radio base station is changed. You need to know how.

In the latter method of determining a route by central control, a wireless packet for determining a route is transmitted from the central base station to each wireless base station in a broadcast manner, and each wireless base station determines independently. It sends the route to the central base station,
The number of wireless packets transmitted to determine a route increases.

Further, the optimum route between the radio base station and the central base station is determined by the transmission time of the radio packet from the central base station to the radio base station. Is not optimal as a route for wireless packets from the wireless base station to the central base station.

The present invention has been made in view of the above-described problems, and does not cause a decrease in the use efficiency of a wireless section due to an increase in the number of wireless packets for determining a route in setting a route for transmitting and receiving wireless packets in a wireless network. It is an object of the present invention to provide means for determining an optimal route for transmitting and receiving wireless packets.

[0012]

According to the invention, the above-mentioned object is solved by the means described in the claims.

That is, according to the first aspect of the present invention, each radio base station records measurement result information necessary for calculating an optimum route between each radio base station and the central base station in transmission and reception of radio packets, When the measurement result information changes, each wireless base station transmits the measurement result information to the central base station. In this case, if there is a wireless packet to the central base station, the wireless packet is transmitted to the central base station. Add, if the wireless packet does not exist, relay by wireless packet only measurement result information,

In the relay base station, if the received radio packet is a radio packet containing only the measurement result information,
If there is a radio packet to another central radio base station, the measurement result information is written in the radio packet and transmitted to the central base station. When the central base station receives the radio packet, the measurement result is added to the radio packet. Check whether the information is recorded, and if so, retrieve and save the measurement result information,

From the measurement result information, each radio base station, and
Calculate the optimal route between the central base stations, and the central base station transmits the optimal route to each wireless base station toward the wireless base station. In that case, if the optimal route is transmitted to the route to the wireless base station. If there is a radio packet to perform at the central base station, the radio packet is added to the radio packet and transmitted. If not, the radio packet is transmitted to the radio base station in a radio packet describing only the optimal route. If the wireless packet describes an optimal route to the own wireless base station, the optimal route is extracted from the wireless packet and the route is determined.

According to a second aspect of the present invention, in the first aspect, the delay time between each wireless base station and the central base station is used as the measurement result information, and each wireless base station determines an optimum route from the central base station. This is a route determination method that determines the route with the least delay time.

According to a third aspect of the present invention, in the first aspect of the present invention, an optimum capacity of a recording device for temporarily recording a radio packet of each radio base station for relaying is used as measurement result information. This is a route determination method in which a route is determined as a route that maximizes the minimum value of the free capacity of the relay base station.

According to a fourth aspect of the present invention, in the first aspect of the invention, the average packet error rate between the radio base stations is used as the measurement result information, and each radio base station uses the optimum route as the optimum route between the relay base stations. This is a route determination method for determining a route having the smallest average packet error rate.

According to a fifth aspect of the present invention, in the second aspect, the reception or transmission time is recorded in the wireless packet,
The central base station and each wireless base station that have received the wireless packet calculate the delay time by comparing the time with their own, record the delay time a predetermined number of times or a fixed time, and calculate the average thereof. This is the route determination method.

According to a sixth aspect of the present invention, in the fourth aspect, the number of radio packets received by each radio base station and the central base station and the number of radio packets retransmitted for calculating the average packet error rate are calculated. This is a path determination method, wherein the number is recorded, and a ratio of retransmitted wireless packets among all arriving wireless packets is calculated as an average packet error rate for recording up to a predetermined time before.

According to a seventh aspect of the present invention, in the first aspect of the present invention, when a plurality of central base stations are present in the wireless network, a plurality of central base stations are obtained from the measurement result information wireless packets received by each wireless base station. Is a route determination method for determining a route to a central base station from which an optimum route is obtained.

In each of the above-mentioned inventions, each radio base station and the central base station measure information necessary for calculating an optimum route between each radio base station and the central base station, and the results are collected. The information required to determine the optimal route and calculate the optimal route is to relay the average delay time between each radio base station, the average packet error rate, and the radio packets of each radio base station. The method differs from the conventional method in that the free space of the recording apparatus for temporarily recording data is used, and that information and route information are added to another wireless packet if possible and transmitted.

Due to this difference, each wireless base station can optimally change the route according to the status of the route, and can efficiently perform wireless packet transmission over the entire network. Further, by adding information used for determining a route to another wireless packet, the wireless space can be used more effectively.

[0024]

FIG. 1 is a diagram showing an example of the configuration of a system to which the present invention is applied. In FIG.
1-2 is a central base station, 2-1 to 2-5 are wireless base stations, 3 is a wireless path through which wireless packets can be directly transmitted and received, 4 is a wired network, and 5 is connected to a wired network. Personal computer.

FIG. 2 is a diagram schematically showing a system configuration for explaining an embodiment of the present invention. Numeral 10 denotes a radio path through which radio packets can be directly transmitted and received,
Reference numeral 12 denotes a central base station, reference numerals 13 to 19 denote wireless base stations, and reference numeral 20 denotes a wired communication network connecting the central base stations 11 and 12.

FIGS. 3 and 4 are flowcharts showing the procedure of the route determination method in the central base station. FIGS. 5 and 6 are flowcharts showing a procedure for transmitting a measurement result information search packet in the central base station.

FIG. 6 is a flowchart showing a procedure of a route determining method in the radio base station. An embodiment of the present invention will be described below with reference to FIGS. Symbols such as S1-A and S2-C in parentheses in the description correspond to the same symbols in FIGS.

In FIG. 2, central base stations 11 and 12 are 1
Recognizing the existence of the radio base stations 3 to 19, each radio base station knows the route to the central base station in some way, and the central base station also determines the existence of the route 10 and the route 10 It is assumed that all average delay time information is stored.

Each radio base station and the central base station calculate the average delay time of the radio packet when transmitting and receiving the radio packet (S1-A, S2-A). Since the central base station and the radio base station can know the exact time using a clock or the like, the time data is added to the measurement result information search packet when a radio packet is received, and transmitted to the next central base station or radio base station. I do.

The next central base station or radio base station can calculate the delay time due to the transmission / reception of the radio packet from the data of the reception time at the previous central base station or radio base station described in the radio packet at the time of reception. it can. Each radio base station and the central base station record a past delay time. Therefore, the average delay time can be calculated by calculating the time average of the delay times up to a certain time before.

As an example of the route change mechanism, consider a case where the average delay times of the routes 10 are all equal. Here, for simplicity, the average delay time when the central base station 11 transmits a wireless packet to the wireless base station 13 is set to 1. At this time, each wireless base station determines a route so as to minimize the sum of the average delay times to the central base station. Also,
At this time, the processing time in the radio base station is included in the average delay time. In the above example, "Table 1"
And a route as shown in "Table 2" is set.

[0032]

[Table 1]

[0033]

[Table 2]

That is, Table 1 shows the route of each radio base station to the central base station when the average delay time between all the radio base stations and the central base station is the same. "Table 2" shows the route of the central base station to each wireless base station when the average delay time between all the wireless base stations and the central base station is the same.

Each wireless base station calculates an average delay time with an adjacent base station and records it in its own recording device. Then, when the average delay time changes significantly as compared with the past average delay time and the route needs to be changed, the measurement result information is notified to the central base station (S2-B). In order to inform the central base station of the measurement result information, the wireless base station checks whether there is a wireless packet from the temporary storage device to the central base station.

If there is a wireless packet to the central base station in the temporary recording device, the wireless packet is added with the measurement result information and transmitted. If there is no wireless packet to the central base station in the temporary recording device, the wireless packet including only the measurement result information is transmitted to the central base station.
The radio base station receiving the radio packet to the central base station,
If it is a wireless packet including only the measurement result information, the measurement result information is added to another wireless packet transmitted to the central base station and relayed (S2-C).

As an example of the route change mechanism, it is assumed that the quality of the radio space changes when the above-described route is determined. Here, for example, it takes three times as long to transmit a wireless packet from the wireless base station 16 to the wireless base station 14, and it takes a long time to transmit a wireless packet from the wireless base station 14 to the central base station 11. Assume that it took three times as long.

At this time, first, the radio base station 14 which has received the radio packet from the radio base station 16 transmits the radio packet based on the transmission time written in the radio packet and the clock of the radio base station. It is known that three times the time has elapsed (S2-A).

Therefore, the radio base station 14 informs the central base station 11 of the information that the average delay time in the route from the radio base station 16 to the radio base station 14 has been tripled in the radio packet (S2-B). .

First, the radio base station 14 checks whether or not a radio packet to the central base station 11 exists in the radio packet temporary recording device of its own radio base station. In this example, it is assumed that there is no wireless packet to the central base station. In that case, the wireless base station 11 transmits a wireless packet including only the measurement result information to the central base station 11. The wireless base station that transmitted the wireless packet (in this case, the wireless base station 16), the wireless base station that received the wireless packet (in this case, the wireless base station 14), and the average delay time (in this case, 3) are described. The condition for transmitting the measurement result information to the central base station is determined in advance by each radio base station.

When the central base station 11 receives the wireless packet transmitted from the wireless base station 14, the central base station 11 calculates the time at which the wireless base station 14 transmits the wireless packet and the clock of the central base station 11 described in the wireless packet. It is known that the average delay time on the route from the wireless base station 14 to the central base station 11 has tripled (S1-A). Further, it is known from the information of the average delay time added to the wireless packet that the average delay time in the transmission of the wireless packet from the wireless base station 16 to the wireless base station 14 has tripled.

Since the average delay time has changed significantly, the route to each wireless base station is updated. The central base station selects a route that passes through the route with the average delay time changed from the current route information. For each route, the total average delay time between the central base station and the wireless base station is minimized. A route is searched (S1-B).

The routes having the relay from the radio base station 16 to the radio base station 14 and the relay from the radio base station 14 to the central base station 11 are shown in Table 1. The route to the station 11 has an average delay time of 1. The route from the wireless base station 15 to the central base station 11 has an average delay time of 3. The route from the wireless base station 16 to the central base station 11 has an average delay time of 2. The route from the wireless base station 17 to the central base station 11 and the average delay time are 2.

Therefore, if a more optimal route is searched for, the route from the radio base station 14 to the central base station is:
3-11. The average delay time is 2. The route from the wireless base station 15 to the central base station is 15-1.
6-18-19-12. The average delay time is 4. The route from the wireless base station 16 to the central base station is 16-1.
8-19-12. The average delay time is 3. The route from the wireless base station 17 to the central base station is 17-1.
4-13-11. The average delay time is 3.

Since each central base station is connected by a wired network, the radio base station can select the optimal central base station (central base station 11 or central base station 12). The central base station 11 notifies the wireless base station of the updated route (S1-F). At this time, as in the case where the wireless base station has transmitted the measurement result information to the central base station, if there is a wireless packet to the target wireless base station, route information is added to the wireless packet (S1-C), and If not, a wireless packet containing only the route information is transmitted.

If the wireless base station that relays the wireless packet can add the route information to another wireless packet, the wireless packet is added and transmitted (S1-D). Further, transmission of the route information to the wireless base station on the same route uses the same wireless packet (S1-E).

The radio packets transmitted from the radio base stations 15 and 16 have a shorter average delay time on the route to the central base station 12, so that the central base station 11 first communicates with the central base station 12 via a wired network. After transmitting the packet, the central base station 12 transmits the route to the radio base station 15 and the radio base station 16. At this time, the central base station 12 also updates the information of the average delay time between each wireless base station and the central base station recorded in its own base station.

Since the route for transmitting a wireless packet from the wireless base station 15 to the central base station 12 includes the route for transmitting a wireless packet from the wireless base station 16 to the central base station 12, the wireless base station 15 to central base station 12
A path for transmitting a wireless packet to the wireless base station and a path for transmitting a wireless packet from the wireless base station 16 to the central base station 12 are both added to the wireless packet and transmitted to the wireless base station 15.

When relaying the wireless packet to the wireless base station 15, the wireless base station 16 extracts path information for transmitting the wireless packet from the wireless base station 16 to the central base station 12. Each wireless base station that has received the route information between each wireless base station and the central base station updates the route (S2-D) and uses a new route from the transmission of the next wireless packet. In the present invention, it is also possible to use not the average delay time but the average packet error rate or the free capacity of the recording device for recording the radio packets of the relaying radio base station as the measurement result information.

Here, the average packet error rate is a retransmitted radio packet among all the received radio packets during a certain period of time. Since a route with a large average packet error rate frequently retransmits wireless packets, determining the route as a route for wireless packets lowers the efficiency of wireless space utilization. Therefore, by determining a route that does not pass through a route having a high average packet error rate, it is possible to avoid a reduction in the use efficiency of the wireless space.

To determine the average packet error rate, each radio base station and the central base station measure and record the error rate of each radio packet. Each radio base station and the central base station record the average packet error rate from each adjacent base station, and if the average packet error rate changes significantly from the previous average packet error rate, it is considered necessary to change the route. In this case, information on the average packet error rate is added to the radio packet to the central base station and the packet is transmitted to the central base station.

As the information on the average packet error rate, the average packet error rate and the radio base station and the central base station on the radio packet transmitting side and the receiving side of the path where the average packet error rate is measured are described. The central base station extracts the information of the average packet error rate from the wireless packet, updates the information of the average packet error rate of each route of the central base station, and updates the route between the wireless base stations.

At this time, as a criterion for determining a route, the maximum value of the average packet error rate between the wireless base stations that relay wireless packets among the possible routes between the wireless base stations is the smallest. Use a route. When the free space of the recording device of the wireless base station becomes small, the flow control of the wireless packet is performed, and a control signal for that is also transmitted, so that the use efficiency of the wireless space is reduced.

Therefore, by determining a route that does not pass between the radio base station and the central base station having a small free capacity of the recording device of the radio base station, it is possible to avoid a decrease in the use efficiency of the radio space. Each radio base station and the central base station calculate and record the free space of the recording device for recording the received radio packet at regular intervals. When the free capacity for storing its own wireless packet becomes small, each wireless base station adds information on the current free capacity to the wireless packet and transmits it to the central base station.

The central base station updates the route if the received packet contains information on the free capacity of the radio base station.
As a criterion for updating, of the respective routes between the radio base station and the central base station, the route having the smallest available capacity of the relay base station is used. Then, the information is transmitted to a wireless base station that needs to update the route via a wireless packet or another central base station. By the above method, the route between each radio base station and the central base station is determined.

[0056]

As described above, according to the present invention, the central base station selects the optimum route and the optimum radio base station based on the measurement result information from each radio base station. When setting a route between central base stations, it is possible to prevent wireless packets from concentrating on a certain route. Further, the information transmitted between each radio base station and the central base station for determining the route is added to other wireless packets, thereby preventing an increase in the number of wireless packets sent for determining the route. This has the advantage that the communication volume of the entire system can be increased.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of the configuration of a system to which the present invention is applied.

FIG. 2 is a diagram schematically showing a system configuration for explaining an embodiment of the present invention.

FIG. 3 is a flowchart (part 1) illustrating a procedure of a route determination method in the central base station.

FIG. 4 is a flowchart (part 2) illustrating a procedure of a route determining method in the central base station.

FIG. 5 is a flowchart (part 1) illustrating a procedure of a route determining method in the wireless base station.

FIG. 6 is a flowchart (part 2) illustrating a procedure of a route determining method in the wireless base station.

[Explanation of symbols]

 1-1, 1-2, 11, 12 Central base station 2-1 to 2-5, 13 to 19 Wireless base station 3, 10 Wireless path 4 Wired network 5 Personal computer 20 Wired communication network

Claims (7)

[Claims] 1. A wireless base station in a wireless network comprising a plurality of wireless base stations and a central base station connected to a wired network, wherein data is transmitted and received by wireless packets between the central base station and the wireless base stations. And a route for relaying wireless packets transmitted and received between the central base station and the central base station, wherein each wireless base station determines an optimal route between each wireless base station and the central base station for transmission and reception of wireless packets. Information necessary for the calculation is recorded as measurement result information, and when the measurement result information changes, the information is transmitted to the central base station. When another wireless packet to be transmitted to the station exists, the measurement result information is added to the wireless packet. When the wireless packet does not exist, a new wireless packet is added. Transmitting the measurement result information to the central base station by using the packet, the central base station extracts and stores the measurement result information between each wireless base station and the central base station from the received wireless packet, and stores the information based on the measurement result information. Procedure for calculating the optimal route between the radio base station and the central base station, and when the central base station adds the optimal route to each radio base station to the radio packet and transmits the packet, the route needs to be changed. If the wireless packet passing through the wireless base station is present in a recording device for temporarily recording the wireless packet held by the central base station, the route information is added to the wireless packet, and the wireless packet is If not present, transmitting a wireless packet of only the route information, and each wireless base station extracts the optimum route from the wireless packet and determines a route. Path determination method of a wireless packet in a wireless network. 2. The measurement result information is an average delay time in transmission of a radio packet between each radio base station and a central base station, and an optimum route is such that the total average delay time between each radio base station and the central base station is minimum. 2. The method according to claim 1, wherein the route is a route of a wireless packet. 3. The wireless communication system according to claim 3, wherein the measurement result information is an empty capacity of a recording device for temporarily recording the wireless packet of the wireless base station for relaying the wireless packet, and an optimal route is a wireless packet between the wireless base station and the central base station. 2. The route determination of a wireless packet in a wireless network according to claim 1, wherein the route is a route in which the minimum value of the free space of the recording device of the wireless base station (relay base station) that relays the transmission and reception of the wireless packet is maximum. Method. 4. The measurement result information is an average packet error rate in transmission of a radio packet between each radio base station and a central base station, and the optimum route is determined by the maximum value of the average packet error rate between the relay base stations. The method according to claim 1, wherein the path is a small path. 5. A reception time or a transmission time is recorded in a radio packet, and the central base station and each radio base station receiving the radio packet calculate a delay time by comparing the time with their own time, and calculate the delay time. 3. The method according to claim 2, wherein the time is recorded a predetermined number of times or a predetermined time, and an average is calculated. 6. Record the number of radio packets received by each radio base station and the central base station and the number of retransmitted radio packets, and perform retransmission of all the arriving radio packets for a record up to a predetermined time ago. 5. The method according to claim 4, wherein the ratio of the determined wireless packets is calculated as an average packet error rate. 7. When each radio base station is capable of transmitting a radio packet to a plurality of central base stations according to claim 1, each radio base station can independently transmit a plurality of central base stations based on measurement result information. A method for determining a route of a wireless packet in a wireless network, comprising transmitting a wireless packet from a medium to an optimal central base station.