JP2010093360A - Wireless communication system and roaming method in same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication system wherein, when a wireless terminal is separated from a certain AP and communication quality declines, roaming is accurately performed to such an AP that the certain terminal can obtain higher communication quality. <P>SOLUTION: The wireless communication system includes a plurality of wireless connection apparatuses and at least one wireless terminal. A certain wireless connection apparatus is provided with a disconnection means for disconnecting communication with a certain wireless terminal when radio waves having received field strength higher than the received field strength of radio waves received by the certain wireless connection apparatus from the certain wireless terminal are received by another wireless connection apparatus from the certain wireless terminal, and not responding even when a connection request comes from the certain wireless terminal for a fixed period from then. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless communication system including a plurality of wireless connection devices (hereinafter referred to as AP (Access Point)) or a wireless base station and at least one wireless terminal, and a roaming method therefor.

In a wireless communication system including a wireless connection device or a wireless base station and a wireless terminal, when a wireless terminal moves, all wireless terminals connected to the same AP are connected because the communication speed decreases and the number of retransmissions increases. The problem is that the communication quality is degraded. In particular, when streaming communication (telephone, video, etc.) is performed, if the call quality deteriorates, sound interruptions and image disturbance will be caused. Therefore, there is a method for limiting the number of terminals that can be connected to each AP and the type of terminal ( Alternatively, the problem is solved by assigning priorities according to the characteristics of the data, but in a situation where an unspecified number of wireless terminals are connected, it is impossible to maintain communication quality by these methods.
JP 2005-175932 (29th, 43th, 44th, 49th and 50th paragraphs)

  Taking a wireless LAN as an example of a normal wireless communication system, a terminal always monitors the received electric field strength of an AP in order to maintain the quality of wireless communication, and when this value falls below a certain value, searches for other APs and performs handover. To start. In this method, the threshold value for handover is arbitrarily set on the terminal side depending on the manufacturer and model. For example, if the terminal has a low threshold value, the transmission speed is decreased and the number of playbacks is increased at a low electrolytic strength. May occur. In this case, if data communication is used, the throughput of other terminals under the same AP as the throughput is significantly reduced, and in streaming communication (telephone, video, etc.), the sound is interrupted and the image is distorted. Instead, other terminals under the same AP have problems that sound is interrupted and image distortion occurs.

  Therefore, the present invention provides wireless communication that enables a certain terminal to roam accurately to an AP that can obtain a higher communication quality when the wireless terminal leaves a certain AP and the communication quality deteriorates. The purpose is to provide a system.

  According to the present invention, the wireless connection device includes a plurality of wireless connection devices and at least one wireless terminal, and a certain wireless connection device is stronger than a reception electric field strength of a radio wave received by the certain wireless connection device from a certain wireless terminal. When another wireless connection device receives a radio wave having a received electric field strength from the certain wireless terminal, the communication with the certain wireless terminal is disconnected, and then connected from the certain wireless terminal for a certain period of time. There is provided a wireless communication system comprising a disconnecting means that does not reply even when a request comes.

  According to the present invention, in a roaming method in a wireless communication system including a plurality of wireless connection devices and at least one wireless terminal, a wireless connection device receives the wireless connection device from a wireless terminal. When the other wireless connection device receives a radio wave having a received electric field strength stronger than the received electric field strength of the radio wave, the communication with the certain radio terminal is disconnected. A roaming method is provided, comprising a disconnecting step that does not respond even when a connection request is received from a certain wireless terminal for a certain period of time.

  According to the present invention, when a radio terminal receives radio field strength of radio waves received by each AP from each radio terminal and the communication quality deteriorates, the certain terminal obtains higher communication quality. It is possible to roam accurately to the AP to be used.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  The present invention always provides a high-quality wireless communication system by guiding a terminal that does not perform handover even though the reception field strength of the AP is low to some extent to an AP having a higher reception field strength.

  In order to solve this problem, the wireless terminal transmits a probe request signal to neighboring APs at regular intervals. Each AP measures the reception field strength of the probe request signal, notifies the other AP of the measurement result, and creates a list of reception field strengths of the probe request signal for each AP for each wireless terminal. The probe request signal is a signal transmitted by the terminal when the terminal searches for an AP.

  If an AP has a stronger received field strength of the probe request signal than one AP to which the corresponding terminal is currently connected and can communicate with a higher quality even when viewed from the other AP, If one of the APs has a means for disconnecting the wireless connection of the corresponding terminal, the corresponding terminal is handed over to the AP having the highest received electric field strength for the terminal. Regardless of which, the AP can maintain a certain communication quality by determining which AP each terminal should communicate with.

  Furthermore, even in a system having a plurality of different wireless interfaces, for example, a hybrid wireless terminal combining a PHS (Personal Handy-phone System) and a wireless LAN (Local Area Network), the same function as that hybrid wireless terminal The PHS wireless base station (CS (Cell Station)) and the wireless LAN AP exchange information about the received electric field strength of the probe request signal, thereby providing the same function.

  FIG. 1 shows a wireless communication system according to an embodiment of the present invention as, for example, IEEE (the Institute of Electrical and Electronics Engineers) 802.11 wireless LAN, and shows the positional relationship between a wireless LAN terminal which is a wireless terminal and a wireless connection device (AP). It is shown. Of course, other wireless communication systems may be used.

  In this embodiment, there are two APs, and the wireless LAN terminal 11 that is a wireless terminal is connected to the AP 12 in advance, and performs data communication or streaming communication (telephone, video, etc.). The communication partner at this time is not particularly limited.

  It is assumed that the wireless LAN terminal 11 has moved closer to the AP 13 by moving. According to the conventional method, the wireless LAN terminal 11 monitors the received electric field strength of the radio wave received from the AP 12 as needed. If the AP 12 strength of the wireless LAN terminal 11 does not fall below the threshold value, the wireless LAN terminal 11 remains connected to the AP 12. When this threshold value is low, the AP 12 remains connected despite the presence of the AP 13 in the vicinity, the transmission speed decreases and the number of retransmissions increases, and the communication quality of the wireless LAN terminal 11 deteriorates. Instead, the communication quality of the other wireless LAN terminals 14 connected to the same AP 12 deteriorates. Although it is obvious that the quality is acceptable to some extent in the case of data communication, it is clear that the quality deteriorates. Further, in streaming communication (telephone, video, etc.) that requires real-time characteristics, sound interruption and image disturbance occur. In particular, the wireless LAN terminal 14 under the control of the AP 12 has the biggest drawback in that quality degradation occurs.

  According to the present embodiment, the wireless LAN terminal 11 has a function of sending an arbitrary signal (radio wave) such as a probe request signal to neighboring APs at a constant cycle, and the AP 12 and AP 13 have signals such as the probe request signal ( By receiving (radio waves), the received electric field strength of signals (radio waves) such as probe request signals received from the wireless LAN terminal 11 can be known. AP 12 and AP 13 have a function of creating a terminal list for each wireless LAN terminal in descending order of reception electric field strength, exchanging each other's list through a wired LAN, etc., and storing the list. That is, each AP can grasp the rank order of received probe request signals for each wireless LAN terminal, and therefore each AP has the highest received probe request signal strength for each wireless LAN terminal. AP can be grasped. Therefore, if the wireless LAN terminal 11 determines that the AP 13 has a higher received electric field strength and the received electric field strength from the wireless LAN terminal 11 is higher when viewed from the AP 13, the AP 12 disconnects the wireless connection of the wireless LAN terminal 11 from the AP 12. Send a signal (such as re-authentication or disauthentication). Here, since there is no point in connecting the wireless LAN terminal 11 to the original connection destination AP 12 after that, the AP 12 ignores the connection request from the wireless LAN terminal 11 for a certain period (for example, 5 seconds). Will work. If the wireless LAN terminal 11 cannot connect to the original AP 12, the terminal 11 connects to the AP 13 having the strongest received electric field strength.

  FIG. 2 shows an example of a sequence used in this embodiment.

  As described above, according to the present embodiment, when the connection device AP is in the immediate vicinity of the wireless terminal in the wireless communication system, by reconnecting from the first connected AP to the nearest AP, This has the effect of preventing performance degradation. Also, the terminal concentrates on a specific AP (for example, if it is an AP near the entrance / exit, it connects to this AP when entering the room, and even if you sit in a seat away from it, it continues to connect to the AP at the entrance / exit, If they overlap, the terminal is always connected to the AP at the entrance / exit), that is, there is an effect of load distribution. Furthermore, by sharing information between APs, an expensive wireless switch or the like is not required, and a wireless communication system can be constructed at a low cost.

  The present invention can be used in a wireless system such as a mobile phone system, a PHS, and an IEEE 802.11 wireless LAN system.

It is a conceptual diagram which shows the outline | summary of the roaming in the radio | wireless communications system by embodiment of this invention. It is a sequence diagram for demonstrating roaming in the radio | wireless communications system by embodiment of this invention.

Explanation of symbols

11, 14 terminal AP12 access point 12
AP13 access point 13

Claims (8)

A plurality of wireless connection devices and at least one wireless terminal;
A certain wireless connection device receives from the certain wireless terminal another wireless connection device a radio wave having a received electric field strength stronger than a received electric field strength of the radio wave received by the certain wireless connection device from a certain wireless terminal. A wireless communication system comprising: disconnecting means that disconnects communication with the certain wireless terminal when a state is established, and does not respond even if a connection request is received from the certain wireless terminal for a certain period of time. . Whether or not another wireless connection device has received a radio wave having a reception field strength stronger than a reception field strength of a radio wave received by the certain wireless connection device from a certain wireless terminal from the certain wireless terminal 2. The wireless communication system according to claim 1, wherein each of the plurality of wireless connection devices includes a sharing unit that shares a received electric field strength of a radio wave received from each wireless terminal. Whether or not another wireless connection device has received a radio wave having a reception field strength stronger than a reception field strength of a radio wave received by the certain wireless connection device from a certain wireless terminal from the certain wireless terminal The wireless terminal transmits a probe request signal periodically, and each wireless connection device measures a received electric field strength of a radio wave of the probe request signal. Or the radio | wireless communications system of 2. The wireless communication system according to any one of claims 1 to 3, wherein a wireless base station is used instead of the wireless connection device. In a roaming method in a wireless communication system comprising a plurality of wireless connection devices and at least one wireless terminal,
A certain wireless connection device receives from the certain wireless terminal another wireless connection device a radio wave having a received electric field strength stronger than a received electric field strength of the radio wave received by the certain wireless connection device from a certain wireless terminal. A roaming method comprising: a disconnecting step of disconnecting communication with the certain wireless terminal when a state is established, and not responding even if a connection request is received from the certain wireless terminal for a certain period. Whether or not another wireless connection device has received a radio wave having a reception field strength stronger than a reception field strength of a radio wave received by the certain wireless connection device from a certain wireless terminal from the certain wireless terminal 6. The roaming method according to claim 5, wherein each of the plurality of wireless connection devices includes a sharing step of sharing the received electric field strength of the radio wave received from each wireless terminal. Whether or not another wireless connection device has received a radio wave having a reception field strength stronger than a reception field strength of a radio wave received by the certain wireless connection device from a certain wireless terminal from the certain wireless terminal The wireless terminal transmits a probe request signal periodically, and each wireless connection device measures a received electric field strength of a radio wave of the probe request signal. Or the roaming method of 6. The roaming method according to claim 5, wherein a wireless base station is used instead of the wireless connection device.

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