JP2004128829A - Radio relay accessing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, when a radio terminal communicates with other terminal by a radio relay, if a radio interface is one, after receiving data is once buffered, the data is transmitted, the data are delayed by this procedure so that a throughput is lowered. <P>SOLUTION: A radio relaying base station 2 has a plurality of radio interfaces 10. One of the interfaces 10 has two operation modes. One of the modes is a mode for communicating with other radio relay base station 2 by polling, and the other is a mode for communicating with each radio terminal 4 by a carrier sense. The throughputs of the individual radio terminals can be made fair by changing times of the two modes in response to the number of the radio terminals or an amount of the data. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wireless access system. In particular, when a wireless terminal accesses a wired network such as the Internet and receives a service, the present invention is applied to a system that enables communication between the wireless terminal and the wired network by wirelessly relaying the base station.
[0002]
[Prior art]
[Non-patent document 1]
J. Jubin, and J.M. D. Tonow, "The DARPA packet radio network protocols," Proc. of IEEE vol. 75, no. 1, Jan. 1987. As a method of performing wireless relay transmission of a base station and communicating with a wireless terminal and a wired network or another wireless terminal, a method using wireless multi-hopping is described in J. Pat. Jubin, and J.M. D. Tornow, "The DARPA packet radio network protocols," Proc. of IEEE vol. 75, no. 1, Jan. 1987. (Non-Patent Document 1).
FIG. 2 shows a configuration example of wireless multi-hopping. For example, when the wireless terminal 7a communicates with the wireless terminal 7d, the communication is realized by the other wireless terminals 7b and 7c relaying a packet. Specifically, the packet 30a transmitted by the wireless terminal 7a is received by the wireless terminal 7b. The wireless terminal 7b transmits the received packet as a packet 30b. The packet 30b is received by the wireless terminals 7a and 7c. Since the wireless terminal 7a knows that the packet is transmitted by itself, it does not discard the packet 30b and transfer it to another wireless terminal. The wireless terminal 7c further transmits the packet 30c, and the wireless terminal 7b and the wireless terminal 7d receive the packet 30c. Since the wireless terminal 7b knows that the packet is transmitted by itself, the wireless terminal 7b discards the packet. Since the wireless terminal 7d is a packet addressed to the own station, the wireless terminal 7d transmits the packet 31a to notify the wireless terminal 7a of the transmission source that the packet has been normally received. The packet 31a is transferred similarly to the packet 30, and transmitted to the wireless terminal 7a. This allows the wireless terminals 7a and 7d to transmit and receive data via the other wireless terminals 7b and 7c, even if a wireless signal does not reach directly.
FIG. 3 shows another example of the configuration of the wireless relay system. In the above, an example in which everything is configured only with wireless terminals has been described. However, as shown in FIG. There is known a method of arranging a wireless relay base station and expanding a service area on the same principle as that of the above-described wireless multi-hopping. In this case, between the wireless terminal and the relay base station or between the relay base station and the wired base station, for example, data is transmitted by a multiple access method using carrier sense according to IEEE802.11b which is a wireless LAN standard. Transmission and reception are performed.
[0003]
[Problems to be solved by the invention]
However, in the wireless multi-hopping method disclosed in Non-Patent Document 1 or the like for connecting to a wired network, a base station that performs wireless relay has only one wireless interface. Therefore, at the time of wireless relay, communication with two locations cannot be performed at the same time. This is because the wireless relay base station cannot communicate with another base station while the wireless relay base station is communicating with the wireless terminal. Therefore, when a wireless relay base station having only one wireless interface is used, the throughput is reduced by wireless relay. A solution to this problem is to provide a wireless relay base station with a plurality of wireless interfaces so that it can simultaneously communicate with another base station while the wireless relay base station is communicating with one wireless terminal. It is.
FIG. 4 shows an example in which a plurality of wireless terminals connect to a wired network via a wireless relay base station by multiple access using carrier sense. The wired base station includes a wired network interface 11 and a wireless interface 10. The wireless relay base station has two wireless interfaces 20. The wireless interface (U) 20a is used for communication with the wired network side, and the wireless interface (D) 20b is used for communication with another wireless relay base station 2 and the wireless terminal 4. The wireless terminal 4 has one wireless interface and communicates with the wireless interface (D) 20b of the wireless relay base station 2 or the wireless interface 10 of the wired connection base station 1. These wireless communications use a multiple access method based on carrier sense generally used in a wireless LAN.
FIG. 5 shows a ratio of data from each wireless terminal 4 passing through the wired connection base station 1 when the wireless terminals 4a, 4b, and 4c simultaneously access the wired network 5. The packets 60a and 60b are transmitted from the wireless terminal 4c to the wireless relay base station 2b. The wireless relay base station 2b relays the packets 60a and 60b and transmits the packets 60a and 60b to the wireless relay base station 2a. At this time, when the wireless terminal 4b also transmits to the wireless relay base station 2a, packets from the wireless relay base station 2b and the wireless terminal 4b are transmitted to the wireless relay base station 2a at the same ratio by multiple access by carrier sense. The wireless relay base station 2a transmits data of the wireless terminals 4b and 4c to the wired connection base station 1. At this time, when the wireless terminal 4a also transmits to the wired connection base station 1, the packets from the wireless relay base station 2a and the wireless terminal 4a are transmitted to the wired connection base station 1 at the same ratio by the carrier sense similarly to the wireless relay base station 2a. Transmitted. Therefore, the data amount of the wireless terminals 4b and 4c is half that of the wireless terminal 4a. Although FIG. 4 shows an example in which the number of wireless terminals is three, generally, as the number of wireless relay base stations and the number of connected wireless terminals increase, wireless terminals that pass through the wireless relay base station more often become other terminals. There is a problem that the throughput is reduced as compared with the above.
[0004]
[Means for Solving the Problems]
In order to achieve the object of the present invention, in a wireless relay access system, a wired connection base station transmits a wired communication interface for communicating with a wired network, at least one wireless communication interface, and data between the wired communication interface and the wireless communication interface. With the ability to transfer,
The wireless relay base station has a plurality of wireless communication interfaces and a function of transferring data between the wireless communication interfaces,
The wireless terminal has a function of performing wireless communication with a wireless communication interface of the wired connection base station or the wireless relay base station,
The first wireless communication interface of the wireless relay base station receives data from a wired network and transmits data to the wired network, and includes a wireless communication interface of the wired connection base station or the wireless relay base station, and communication means by polling. ,
The other wireless interface of the wireless relay base station transmits data from a wired network to another wireless relay base station or a wireless terminal by polling and multiple access using carrier sense, or transmits data from another wireless relay base station or a wireless terminal. A means for receiving data from the terminal to the wired network is provided.
Thereby, even when the number of relay stages when a wireless terminal connects to a wired network increases, a throughput equivalent to that of another wireless terminal can be obtained.
In order to achieve another object of the present invention, there is provided means for changing a ratio of a multiple access time by polling and carrier sense according to the number of wireless terminals wirelessly connected to the wired connection base station and the wireless relay base station. Since it is easy to grasp the number of connected terminals, the ratio of multiple access by polling and carrier sense can be easily calculated.
In order to achieve another object of the present invention,
Means for changing the ratio of the multiple access time by polling and carrier sense according to the amount of traffic wirelessly connected to the wired connection base station and the wireless relay base station. Since the amount of data differs for each connected terminal, this correspondence makes it possible to determine the ratio of multiple access by polling and carrier sense without waste.
According to another aspect of the present invention, a base station that performs wireless relay includes a plurality of wireless interfaces, and one of the wireless interfaces includes two operation modes. One of the operation modes is a mode for performing communication with another wireless relay base station by polling, and the other operation mode is a mode for performing communication with a wireless terminal by carrier sense. By changing the time between the two operation modes according to the number of wireless terminals and the amount of data, the throughput of each wireless terminal can be made fair. The subject of the present invention includes circuits and devices constituting each of the above means, and systems and methods using them.
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a configuration of a wireless relay system according to an embodiment of the present invention. The wireless relay system includes a wired connection base station 1, a wireless relay base station 2, a wireless terminal 4, and a wired network 5.
The wired connection base station 1 includes a wired interface 11 for connecting to the wired network 5 and a wireless interface 10 for wirelessly communicating with another wireless relay base station 2 and the wireless terminal 4.
The wireless relay base station 2 includes two wireless interfaces 20. The wireless interface 20a is used for wireless communication with the wireless relay base station 2 or the wired connection base station 1 near the wired network 5 when relaying data. The wireless interface 20b is used for wireless communication with other wireless relay base stations 2 and wireless terminals 4 for relaying data to the wired network 5 and relaying data from the wired network 5. The wireless interface 20a of the wireless relay base station 2 that performs wireless relay to the wired network 5 side and the wireless interface 20b opposite to the wired network 5 side have different communication procedures. The wireless interface 20a performs communication by polling from the wireless interface 20b of another connected wireless relay base station 2. For example, the wireless interface 20a of the wireless relay base station 2a performs communication by polling from the wireless interface 10 of the wired connection base station 1, and the wireless interface 20a of the wireless relay base station 2b communicates by polling from the wireless relay base station 2a. Do. The wireless interfaces 10 and 20b have two operation modes. One is a polling mode (PCF mode) for performing communication with the wireless interface 20a of the other connected wireless relay base station 2, and a carrier sense for communicating with the directly connected wireless terminal 4. This is a mode (DCF mode) in which communication is performed based on this.
FIG. 6 is a diagram for explaining the operations of the DCF mode and the PCF mode of the wired connection base station 1 and the wireless relay base station 2 according to the present invention. The wireless terminal 4c communicates with the wireless interface (D) 20b of the wireless relay base station 2b in the DCF mode. Since the wireless relay base station 2b does not need to connect to another wireless relay base station, all communication is performed in the DCF mode. Communication between the wireless interface (U) 20a of the wireless relay base station 2b and the wireless interface (D) 20b of the wireless relay base station 2a is performed in the PCF mode. Since the wireless relay base station 2a needs to communicate with the wireless relay base station 2b and the wireless terminal 4, the wireless relay base station 2a uses the DCF mode for communication with the wireless terminal and uses the PCF mode for communication with the wireless relay base station. At this time, the wireless relay base station 2a determines a time for communicating with the wireless relay base station 2b in the PCF mode in consideration of the number of wireless relay terminals connected to the wireless relay base station 2b.
The wireless interface 10 of the wired connection base station 1 communicates with the wireless interface (U) 20a of the wireless relay base station 2a and the wireless terminal 4a. Like the wireless interface (D) 20b of the wireless relay base station 2a, the PCF mode is used when communicating with the wireless relay base station 2a, and the DCF mode is used when communicating with the wireless terminal 4a. In the case of FIG. 6, the wireless terminal communicating via the wireless relay base station 2b is one wireless terminal 4c, and the wireless terminal directly communicating with the wireless relay base station 2a is one wireless terminal 4b. Since the number is the same, the operation time in each of the PCF mode and the DCF mode is the same. The two wireless terminals that communicate via the wireless relay base station 2a are the wireless terminals 4b and 4c, and the wireless terminal that directly communicates with the wireless relay base station 2a is one wireless terminal 4a. Therefore, the time for operating in the PCF mode is twice as long as the time for operating in the DCF mode.
FIG. 7 shows a configuration of the wireless relay base station in the embodiment of the present invention. The wireless relay base station 2 includes a CPU 22, a ROM 23, a RAM 24, an interface (U) 20a, and an interface (D) 20b. The CPU 22 performs communication protocol control, control of PCF and DCF modes, and routing processing. The ROM 23 stores a program for operating the CPU 22. The RAM 24 stores transmission / reception data, programs, temporary variables, and the like. The interface (U) 20a is a wireless interface connected to the wired network 5 side. In the wired connection base station, this interface is a wired communication interface for wired connection. The interface (D) 20b is a wireless interface for communicating with another wireless relay base station 2 or wireless terminal 4. It operates by switching between DCF mode 213 and PCF214 mode. The CPU 22, the ROM 23, the RAM 24, and the interface 20 are interconnected via a bus 25. Data received via the interface 20 is stored in the RAM 24, and under the control of the CPU 22, determines whether the data is addressed to the own station or data to be transferred to another device. When the data needs to be transferred to another device, the data is transferred to another interface 20.
FIG. 8 illustrates the operation of the wireless interface 10 of the wired connection base station 1 and the wireless interface 20b of the wireless relay base station 2 according to the present invention.
After the operation starts (200), a beacon frame is transmitted to notify the wireless terminal 4 of the presence of the wired connection base station 1 or the wireless relay base station 2 (201). The beacon frame is transmitted periodically and used for newly joining the wireless terminal 4. If there is a new wireless terminal 4, a connection request is issued to the base station that transmitted the beacon frame, and the base station receives this (202). If there is a connection request from the new wireless terminal 4, it is registered in a terminal table provided in the storage area of the base station. Details of the terminal table will be described later. After the registration of the new wireless terminal is completed, the timer value in the DCF mode is set (204), and the operation is started in the DCF mode (213). Until the timer in the DCF mode times out, if there is data to be transmitted to the wireless terminal, the channel availability is checked by carrier sense (206), and if there is, the data is immediately transmitted (207). Data is transmitted to the wireless terminal, and if there is data received from the wireless terminal, a transfer destination is determined from a destination address in the received data. After the timer in the DCF mode times out (208), the mode shifts to the PCF mode (214). In the PCF mode, if there is data to be transmitted to the wireless relay base station 2 in the downlink direction (209), the data is transmitted (210). The polling ratio is changed according to the presence or absence of data from the downlink (211), and data of the base station from the downlink is received (212). After the PCF mode ends, the operation of transmitting a beacon frame again is repeated.
FIG. 9 illustrates the terminal table of the present invention. The terminal table 300 is prepared in a storage area in the wired connection base station 1 and the wireless relay base station 2. It is composed of a terminal group A (301) with which the base station directly communicates and a terminal group B (302) which is terminal information received by the base station from another wireless relay base station 2. The terminal table 300 of the base station is further transmitted to the wired connection base station 1 or the wireless relay base station 2 on the upstream side, and is used for the terminal group B (302) in the base station that has received it. The information to be transferred to another base station includes the address of the terminal and the amount of data that each terminal intends to transmit to the higher order. The base station refers to the terminal table 300 and calculates the ratio between the DCF mode and the PCF mode. As a method of calculating the ratio, there is a method of making the ratio equal to the ratio of the number of terminal addresses in the terminal table 300. Further, it may be obtained from the ratio of the total value of the amounts of uplink data and downlink data. In this case, there is no need to access the wireless terminal 4 that does not need to transmit and receive, and the throughput of the entire system is improved.
[0005]
【The invention's effect】
According to the present invention, it is possible to provide a wireless access system in which the throughput according to the number of wireless relay stages is equalized.
According to the present invention, it is possible to eliminate the need for more than two wireless communication interfaces, which are the minimum wireless communication interfaces, in the wireless base station.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a wireless relay system according to a first embodiment of the present invention.
FIG. 2 is a diagram showing one example of a configuration of a conventional wireless relay system.
FIG. 3 is a diagram showing another example of the configuration of a conventional wireless relay system.
FIG. 4 is a diagram showing a description of a conventional example.
FIG. 5 is a diagram showing a state of packet transmission in a conventional example.
FIG. 6 is a diagram showing a state of packet transmission according to the embodiment of the present invention.
FIG. 7 is a diagram showing a configuration of a wireless relay base station according to the embodiment of the present invention.
FIG. 8 is a diagram illustrating an operation flow of the base station according to the embodiment of the present invention.
FIG. 9 is a diagram illustrating the structure of a terminal table in a base station according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Wire connection base station, 2 ... Wireless relay base station, 4 ... Wireless terminal, 5 ... Wire network, 10 ... Wire communication interface, 11 ... Wire communication interface, 20 ... Wire communication interface, 21 ... Antenna, 22 ... CPU, 23 ... ROM, 24 ... RAM, 25 ... Bus, 30-60 ... Wireless packet, 200-212 ... Base station operation 213 ... DCF mode, 214 ... PCF mode, 300 ... Terminal table, 301 Terminal group A, 302 ... Terminal group B.

Claims (4)

A wired connection base station comprising a wired communication interface for performing communication with a wired network and at least one wireless communication interface, and having a function of transferring data between the wired communication interface and the wireless communication interface;
A wireless relay base station having a plurality of wireless communication interfaces and having a function of transferring data between the wireless communication interfaces,
A wireless terminal that performs wireless communication with a wireless communication interface of the wired connection base station or the wireless relay base station,
The first wireless communication interface of the wireless relay base station includes means for communicating with a wireless communication interface of a wired connection base station or a wireless relay base station for receiving data from a wired network and transmitting data to the wired network. ,
Another wireless interface of the wireless relay base station transmits data from the wired network to another wireless relay base station or wireless terminal, or receives data from another wireless relay base station or wireless terminal to the wired network. With means,
The first wireless communication interface includes means for performing communication by polling from another wireless relay base station or a wired connection base station, and the other wireless communication interface includes multiple access means by polling and carrier sense. Wireless relay access system characterized. The wireless relay device according to claim 1, further comprising: a unit that determines a polling time of the other wireless communication interface based on the number of wireless terminals wirelessly connected to the wired connection base station and the wireless relay base station. Access system 2. The wireless relay access system according to claim 1, further comprising: means for determining a polling time according to an amount of traffic wirelessly connected to the wired connection base station and the wireless relay base station. 4. The wireless relay access system according to claim 1, wherein the wireless relay base station has one wireless communication interface as the other wireless communication interface.

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