JP2007013250A - Wireless terminal, wireless base station, and wireless communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication method of determining whether relay transfer by a wireless base station is performed for every transmission of one packet. <P>SOLUTION: A wireless terminal includes: a detection means for detecting an address field or the like existing in a header of a received optional packet; a control means for instructing a communication control means to transmit a transfer stop request packet, when the received packet is a packet directly received from the transmission source wireless terminal in an infrastructure mode not via the wireless base station and the destination address is discriminated to be its own terminal on the basis of the address or the like detected by the detection means; and the communication control means for transmitting the transfer stop request packet to the wireless base station when instructed by the control means. The wireless base station includes a control means for instructing the communication control means to stop packet relay transfer of the packet transmitted from the wireless terminal with the address explicitly indicated in the transfer stop request packet when the transfer stop request packet is received. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wireless communication method between a wireless base station and a wireless terminal in a wireless network such as a wireless LAN as shown in FIG. 7, and more specifically, in an infrastructure mode in which the wireless base station relays and forwards packets. The present invention relates to a wireless communication method for improving the throughput of the wireless communication.

  Wireless communication methods standardized by IEEE 802.11 include communication methods using an infrastructure mode and an ad hoc mode. In the ad hoc mode, wireless terminals communicate with each other on a one-to-one basis, and after transmitting one packet, an ACK is returned from the transmission destination wireless terminal to the transmission source wireless terminal.

  On the other hand, in the infrastructure mode, a radio base station intervenes between a source radio terminal and a destination radio terminal, and the radio base station relays and forwards packets. The transmission source wireless terminal transmits a packet to the wireless base station, and ACK is returned from the wireless base station to the transmission source wireless terminal. Next, the radio base station transmits a packet to a destination radio terminal, and an ACK is returned from the destination radio terminal to the source radio terminal.

  A wireless terminal in infrastructure mode uses a plurality of address fields in the MAC frame, where address 1 is the address of the wireless base station, address 2 is the address of its own terminal, and address 3 is the address of the wireless terminal of the transmission destination Is specified. In addition, in the To DS field and From DS field in the MAC frame, flags of 1 and 0 are set, respectively, to clearly indicate that the communication is in infrastructure mode.

  The radio base station that performs relay transfer clearly indicates the address of the transfer destination wireless terminal in address 1, the address of the local station in address 2, and the address of the transmission source wireless terminal in address 3. Also, flags 0 and 1 are set in the To DS field and From DS field in the MAC frame, respectively. Note that when both the To DS field and the From DS field are 0, communication is performed in the ad hoc mode.

  The user sets the communication in the infrastructure mode or the ad hoc mode before starting the communication. Therefore, the wireless terminal once set as the infrastructure mode is always a packet whose address specified in the address 1 is its own terminal, and the To DS field and the From DS field are 0 and 1, respectively, that is, the wireless base station Will receive the relayed packet. As described above, the communication in the infrastructure mode performs relay transfer by the radio base station, so that the communication quality is high but the throughput is lowered.

As a conventional wireless communication method for improving this, there has been a method of switching between packet transmission in the infrastructure mode and packet transmission in the ad hoc mode in order to improve the throughput of the wireless network (see Patent Document 1). According to Document 1, a wireless terminal registers in the table only wireless terminals that are likely to succeed in ad hoc mode packet transfer based on the reception status or the like of packets transmitted to an arbitrary wireless terminal. Only the registered wireless terminal is an application target of the ad hoc mode, and the infrastructure mode via the wireless base station is applied to the other wireless terminals.
Japanese Patent Laid-Open No. 11-252114

  However, since the conventional configuration is switched from the infrastructure mode to the ad hoc mode only after being registered in the table, there is a problem that switching cannot be performed immediately for each packet transmission. In addition, in a wireless LAN system that accommodates wireless terminals that frequently move, the reliability of the contents of the table may be reduced. For example, although communication in the ad hoc mode is difficult, the ad hoc mode There was a problem that communication failed in order to perform communication.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide a radio communication method with high communication quality by determining whether to perform relay transfer by a radio base station for each packet transmission. .

  In order to solve the above-described conventional problems, the wireless terminal of the present invention includes a plurality of address fields in the header of an arbitrary packet received, address / control bit detection means for detecting control bits, and the address / control bits. The arbitrary packet received by the address detected by the detecting means and the control bit is a packet directly received from the source wireless terminal without passing through the wireless base station in the infrastructure mode, and the destination address in the address field is When it is determined by the control means that the wireless base station is instructed to transmit a packet transfer stop request in order to stop the same packet transfer to the self terminal by the wireless base station, And a communication control means for transmitting a packet transfer stop request.

  When the wireless base station of the present invention receives a packet transfer stop request transmitted by the transfer destination wireless terminal prior to the transfer of the wireless base station, the wireless base station of the address specified in the packet transfer stop request is sent to the communication control means. Control means for instructing to stop transfer of the packet transmitted from the terminal and to discard the packet.

  With this configuration, when the transmission destination wireless terminal can directly receive the packet from the transmission source wireless terminal without passing through the wireless base station, the transfer by the wireless base station can be stopped.

  According to the wireless communication method of the present invention, the shortest transfer route can be determined immediately for each packet transmission, and the throughput of the wireless network is improved. In addition, when the packet cannot be received directly, the packet is relayed and transferred by the radio base station as before, so that the communication quality is improved.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a flowchart showing an operation of a radio terminal according to Embodiment 1 of the present invention. FIG. 4 is a diagram illustrating an internal block of a wireless terminal or a wireless base station. MAC is a MAC control unit that performs access control, BB is a baseband processing unit that performs modulation and demodulation, and RF is a high-frequency unit that performs transmission and reception of packets. FIG. 5 is a diagram showing an internal block of a PC card type wireless terminal when connecting to a notebook personal computer or the like. The present invention can also be realized by a PC card type wireless terminal not equipped with a host CPU. FIG. 3 is a diagram showing an internal configuration of the MAC control unit in the present invention. A BB I / F input / output unit is connected to the BB in FIG. 4, and a signal input / output from the MAC is modulated / demodulated by the BB. FIG. 6 is a diagram showing an address field and control bits of a packet defined by 802.11. When the user sets the infrastructure mode, the wireless terminal clearly indicates that the communication is in the infrastructure mode by setting 1 and 0 flags in the To DS field and the From DS field in the MAC frame, respectively. On the other hand, when both the To DS field and the From DS field are 0, communication is performed in the ad hoc mode. In the infrastructure mode, the wireless terminal uses a plurality of address fields in the MAC frame, the address 1 is the address of the wireless base station, the address 2 is the address of the source wireless terminal, and the address 3 is the destination Specify the address of the wireless terminal.

  In FIG. 1, the wireless terminal in the wireless LAN area monitors by carrier sense whether a packet is transmitted to the wireless transmission path in S101. In S102, when any packet is received from the RF of the wireless terminal, the address / control bit detection unit of the wireless terminal detects the header addresses 1 to 3, the To DS field, and the From DS field of the received packet. . If the address / control bit detection unit determines in S103 that the address 1 is the address of the wireless terminal, that is, the address of its own terminal, and is a packet relayed from the wireless base station, in S108 The communication control unit of the wireless terminal outputs a signal for modulation / demodulation to the BB.

  On the other hand, when the address / control bit detection unit detects in S104 that the address 3 of the packet matches the address of the own terminal, the To DS field is 1, and the From DS field is 0, that is, the packet is If it is determined that the packet is directly received from the source wireless terminal without passing through the wireless base station, although it is a packet transmitted in the infrastructure mode, the communication control unit of the wireless terminal in S105 A signal for modulation / demodulation is output to BB. In S106, the control unit of the radio terminal returns a transfer stop request packet to the radio base station to the communication control unit in order to cancel the same packet transfer to the own terminal by the radio base station. Instruct. The instructed communication control unit transmits a transfer stop request packet having the destination address as the packet transmission source wireless terminal after the ACK returned from the wireless base station to the packet transmission source wireless terminal. The radio base station that has received the transfer cancellation request packet can cancel the transfer of the packet transmitted from the radio terminal having the address specified in the transfer cancellation request packet. The communication control unit uses a timer to transmit the transfer stop request packet immediately after the ACK returned from the wireless base station to the packet transmitting wireless terminal.

  The transfer cancellation request packet may be immediately before the ACK returned from the wireless base station to the wireless terminal that is the packet transmission source. In this case, however, timer control of the ACK transmission returned from the wireless base station is required.

  The destination address of the transfer cancellation request packet is the address of the wireless terminal that is the packet transmission source. When the wireless base station in the wireless LAN area receives the transfer cancellation request packet, it detects the address, The relay transfer of the packet transmitted from the wireless terminal is stopped, and the packet stored in the internal buffer is discarded.

  FIG. 2 is a flowchart showing the operation of the radio base station according to Embodiment 1 of the present invention.

  In FIG. 2, the wireless base station in the wireless LAN area monitors the wireless transmission path in S201. The address detector of the radio base station detects addresses 1 to 3 of the received packet. In S203, if the address 1 is different from the address of the radio base station, that is, the own station address, the packet is discarded.

  On the other hand, if the address 1 of the packet matches the own station address, the transmission control unit of the wireless base station returns an ACK to the wireless terminal that is the packet transmission source in S204. Next, when the wireless base station receives a transfer stop request packet from a transfer destination wireless terminal within a predetermined time in S205, the control unit of the wireless base station sends a communication transfer means to the packet transfer stop request. An instruction is given to cancel the relay transfer of the packet transmitted from the wireless terminal having the specified address and to discard the packet.

  In the case of the embodiment in which the wireless base station receives the transfer cancellation request packet immediately before the ACK returned to the packet transmission source wireless terminal, a timer is used and immediately after the transfer cancellation request packet. Reply ACK to.

  On the other hand, when the transfer stop request packet from the transfer destination wireless terminal is not received in S206, the packet transfer is performed as usual.

  The transfer cancellation request packet can also be applied in the 802.11 ACK packet format. When the wireless base station receives an ACK from the transfer destination wireless terminal before transferring the packet, the transfer cancellation request packet is canceled. To do.

  According to this configuration, when the transmission destination wireless terminal can directly receive a packet from the transmission source wireless terminal without passing through the wireless base station, the relay transfer by the wireless base station can be stopped, and one packet A packet can be transmitted by the shortest transfer route for each transmission.

  Note that all the embodiments described above can also be realized as an LSI which is an integrated circuit. These may be individually made into one chip, or may be made into one chip so as to include all or part of the structure.

  The name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

  Further, the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

  Further, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. Biotechnology can be applied.

  A wireless LAN communication system and a wireless communication method including a wireless terminal and a wireless base station according to the present invention have a function that can immediately determine the shortest transfer route for each packet transmission. This is useful as a wireless communication method.

Flowchart showing the operation of the wireless terminal in Embodiment 1 of the present invention Flowchart showing the operation of the radio base station in Embodiment 1 of the present invention The figure which shows the internal structure of MAC of the wireless base station of this invention, and a wireless terminal The figure which shows the internal block of the wireless base station of this invention, and a wireless terminal The figure which shows the internal block of the radio | wireless terminal (PC card type) of this invention The figure which shows the address field and control bit of the packet prescribed | regulated by 802.11 A diagram showing a wireless network such as a wireless LAN

Claims (7)

In a wireless communication system composed of a wireless base station and a plurality of wireless terminals, a wireless terminal performing wireless communication,
Address / control bit detection means for detecting a plurality of address fields and control bits in the header of an arbitrary packet received;
Based on the address field and the control bit detected by the address / control bit detection means, the received arbitrary packet is directly received from the source wireless terminal in the infrastructure mode without passing through the wireless base station. If it is determined that the destination address in the address field in the packet is the own terminal, communication control is performed so as to transmit a transfer stop request packet indicating that the same packet transfer to the own terminal by the radio base station is to be stopped. Control means for instructing means;
A wireless terminal comprising: a communication control unit that transmits a transfer stop request packet when a packet transfer stop request is instructed by the control unit. The radio terminal according to claim 1, wherein the address / control bit detection means detects three address fields, a To DS field and a From DS field in a header of a MAC frame, and notifies the control means of the detected information. . The control means is an address received by the address / control bit detection means, which is a packet received directly from the source wireless terminal without passing through the wireless base station in the infrastructure mode and in the address field. When it is notified that the address is its own terminal, the wireless base station transmits a transfer cancellation request packet clearly indicating the address of the source wireless terminal before or after the ACK sent back to the source wireless terminal. The wireless terminal according to claim 1, wherein an instruction is given to the communication control means. In a wireless LAN system configured by a wireless base station and a plurality of wireless terminals, in a wireless base station that performs wireless communication with the wireless terminal,
When the transfer destination wireless terminal receives the packet transfer stop request packet transmitted prior to the transfer of the wireless base station, the packet sent from the wireless terminal at the address specified in the transfer stop request packet is transmitted to the communication control means. A radio base station comprising control means for instructing to cancel transfer and discard the packet. The transfer cancellation request packet can also be applied to an 802.11 ACK packet format, and the wireless base station stops the transfer of the packet when receiving an ACK from a transfer destination wireless terminal before transferring the packet. Item 5. The radio base station according to Item 4. 6. The packet according to claim 5, wherein when the transfer destination wireless terminal receives a transfer stop request transmitted prior to transfer of the wireless base station, a packet to stop transfer is determined at an address specified in the transfer stop request packet. Radio base station. A wireless communication system for performing wireless communication between a wireless base station and a wireless terminal,
The wireless terminal is
Address / control bit detection means for detecting a plurality of address fields and control bits in the header of an arbitrary packet received;
Based on the address field and the control bit detected by the address / control bit detection means, the received arbitrary packet is directly received from the source wireless terminal in the infrastructure mode without passing through the wireless base station. If it is determined that the destination address in the address field in the packet is the own terminal, communication control is performed so as to transmit a transfer stop request packet indicating that the same packet transfer to the own terminal by the radio base station is to be stopped. Control means for instructing means;
A communication control means for transmitting a transfer stop request packet when a packet transfer stop request is instructed by the control means;
The radio base station is
When a transfer destination wireless terminal receives a transfer cancellation request packet transmitted prior to the transfer of the wireless base station, transfer of a packet transmitted from the wireless terminal of the address specified in the transfer cancellation request packet to the communication control means A wireless communication system comprising control means for instructing to cancel the packet and discard the packet.

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