JP2007013553A - Wireless communication system, wireless base station apparatus, and wireless communication terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication system and wireless base station apparatus capable of setting an appropriate handover condition in accordance with protocols used for communication and an amount of data to be used for the communication. <P>SOLUTION: The base station 20 controls communication with a user terminal 10. A handover control part 24 of the base station 20 sets a condition for handing over the user terminal 20 on the basis of either the kind of protocols of application which the user terminal 10 is using or the amount of data and notifies the user terminal 10 of the handover condition. Then, when the condition is met, the handover control is carried out. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a radio communication system, a radio base station apparatus, and a radio communication terminal apparatus that control radio communication performed between a radio communication terminal such as a mobile phone and a base station.

  In a communication system for controlling communication between a mobile phone, a personal handyphone system (PHS), a car phone, and other wireless communication terminals, generally in a service providing area where the service is provided. Base stations are arranged at predetermined intervals (for example, about several kilometers). With this arrangement, connection between any one or more of the base stations and the wireless communication terminal is always ensured in the entire service providing area.

  In the above communication system, when a wireless communication terminal existing in the communication area of a certain base station moves outside the communication area of the base station, the connection with the base station is set to another adjacent base station. Control (so-called handover or handoff) for switching to a connection with a station is performed. By performing such handover, seamless communication is realized in the communication system.

In the following Patent Document 1, when a wireless communication terminal performs location registration with respect to a base station, the received FER value is compared with a reference value of a frame error rate (FER) transferred from the base station. When the measurement result is above the reference value and the RSSI (Received Signal Strength Indicator) value is below the reference value, it is determined that the wireless communication terminal is used in a weak electric field region. A technique for handing over to another base station is disclosed.
JP 2000-50337 A

  By the way, wireless communication terminals in recent years have become multifunctional, and in addition to voice calls, mail transmission / reception, or browsing (browsing) of the WWW (World Wide Web), streaming (viewing multimedia data such as video and audio) That can be reproduced at the same time as the reception of multimedia data is also realized. In such a wireless communication terminal, a plurality of protocols are implemented, and communication is performed by switching to an appropriate protocol according to the type of data to be transmitted / received.

  In addition, the method of sending data to be transmitted to the wireless terminal device differs depending on the type of data received by the wireless terminal device. For example, in the above streaming, it is important that video or audio is continuously reproduced without interruption, and it is appropriate to transmit a certain amount of data so that it is continuously received by the wireless terminal device. is there. On the other hand, in the above browsing, unlike streaming, it is important that one screen (one page) is displayed in a short time, and transmission is performed so that more data is received by the wireless terminal device at a time. Is appropriate.

  In Patent Document 1 described above, the handover condition is set based only on the FER value, and the protocol and the data amount used for communication are not considered at all. For this reason, at the time of handover, for example, video or audio may be interrupted during streaming, or it may take time to display a screen during browsing.

  The present invention has been made in view of the above circumstances, and provides a radio communication system and a radio base station apparatus capable of setting an appropriate handover condition in accordance with a communication procedure such as a protocol used for communication. The purpose is to do.

In order to solve the above problems, a wireless communication system of the present invention detects a communication state of wireless communication performed between a base station and a wireless communication terminal, and hands over the wireless communication terminal according to the communication state. In the wireless communication system to be performed, a determination is made as to whether or not handover of the wireless communication terminal is necessary, and when it is determined that handover is necessary, handover control means for performing handover control, and between the wireless communication terminal and the base station Communication procedure detecting means for detecting a communication procedure used for the wireless communication between the two, and the handover control means is determined to be required for handover according to the communication procedure detected by the communication procedure detecting means. It is characterized by comprising condition setting means for setting a handover condition.
Here, in the wireless communication system of the present invention, the condition setting means sets a disconnection avoidance degree according to the communication procedure, and sets a higher threshold value for the handover condition for a communication procedure with a higher disconnection avoidance degree. It is characterized by.
The wireless communication system of the present invention further includes data amount detection means for detecting the amount of data communicated between the wireless communication terminal and the base station, wherein the condition setting means is in accordance with the communication procedure. The handover condition to be set is changed according to the data amount.
Here, the radio communication system of the present invention is characterized in that the condition setting means sets the threshold value of the handover condition lower when the data amount is large than when the data amount is small. It is said.
In order to solve the above problems, a radio base station apparatus according to the present invention includes a radio communication unit that performs radio communication with a radio communication terminal, a communication state detection unit that detects a communication state of the radio communication with the radio communication terminal, and In a radio base station apparatus comprising handover control means for handing over the radio communication terminal according to the communication status detected by the communication status detection means, used for communication with the radio communication terminal Communication setting detecting means for detecting a communication procedure to be performed, wherein the handover control means sets a condition for handing over the radio communication terminal according to the communication procedure detected by the communication procedure detecting means. It is characterized by having.
The radio base station apparatus of the present invention further includes a data amount detection unit that detects an amount of data communicated with the radio communication terminal, and the condition setting unit is set according to the communication procedure. The handover condition is changed according to the data amount.
In order to solve the above-described problem, a wireless communication terminal apparatus according to the present invention includes a wireless communication unit that performs wireless communication with a wireless base station apparatus, and a communication state detection that detects a communication state of the wireless communication with the wireless base station apparatus. Wireless communication with the radio base station apparatus in a radio communication terminal apparatus comprising: a communication request means for performing a handover request according to the communication state detected by the communication state detection means A communication procedure detecting means for detecting a communication procedure used in the communication procedure, wherein the handover request means sets a condition for performing the handover request according to the communication procedure detected by the communication procedure detection means It has the means.

  According to the present invention, it is possible to set an appropriate handover condition according to a communication procedure such as a protocol used for communication. As a result, it is possible to suppress problems during handover.

  Hereinafter, a radio communication system, a radio base station apparatus, and a radio communication terminal apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram schematically showing the overall configuration of a communication system and the main configuration of a radio base station apparatus according to an embodiment of the present invention. As shown in FIG. 1, the wireless communication system of this embodiment includes a user terminal 10 as a wireless communication terminal, a base station 20 as a wireless base station device, and a network 30 such as the Internet. Although a plurality of user terminals may be connected to the base station 20, it is assumed here that one user terminal 10 is connected to the base station 20 for simplicity.

  The user terminal 10 is a notebook personal computer including wireless communication devices such as a mobile phone, a PHS, a car phone, and a wireless card 11. In the present embodiment, a case where the user terminal 10 is a personal computer will be described as an example. The user terminal 10 has a wireless card 11 inserted therein for wireless communication with the base station 20. The user terminal 10 includes an input device 12 such as a keyboard operated by a user, and a display 13 such as a liquid crystal display device or an organic EL device.

  In the user terminal 10, communication performed by an internal storage device such as a CPU (Central Processing Unit), a ROM (Read Only Memory) and a RAM (Random Access Memory), an external storage device such as a hard disk, and a wireless card 11 is performed. A communication control unit to be controlled and a speaker (both not shown) are provided. Further, the user terminal 10 is mounted with application programs such as a mailer for sending and receiving mail, a browser for browsing, and a player for displaying streaming video on the display 13 and generating sound by a speaker.

  Further, the user terminal 10 typically includes a plurality of communication protocols (communication procedures) such as FTP (File Transfer Protocol), HTTP (Hyper Text Transfer Protocol), and POP / SMTP (Post Office Protocol / Simple Mail Transfer Protocol). A means (application) for performing communication according to the above is implemented. The FTP is a protocol suitable mainly for sending and receiving files between computers, the HTTP is a protocol suitable for browsing, and the POP / SMTP is a protocol suitable for sending and receiving mail. In addition to the above, means (applications) according to various protocols such as RTSP (Real-Time Streaming Protocol) used for streaming, VoIP and RTP (Real-Time Transport Protocol) used for streaming can be mounted. It is.

  The base station 20 includes an antenna 21, a radio unit 22, a modem unit 23, a handover control unit 24, a signal quality measurement unit 25, a data amount measurement unit 26, a protocol monitor unit 27, and a network unit 28. The antenna 21 receives a radio wave transmitted from the user terminal 10 and transmits a signal to be transmitted to the user terminal 10 on the radio wave. The radio unit 22 controls communication with the user terminal 10 performed via the antenna 21. The modem unit 23 demodulates the reception signal output from the radio unit 22 and modulates the signal to be transmitted to the terminal 10. The handover control unit 24 performs handover control when the user terminal 10 moves out of the communication area of the base station 20 and when the user terminal 10 moves into the communication area of the base station 20.

  The handover control unit 24 is provided with a condition setting unit (not shown) as condition setting means for setting a handover condition. The condition set by the condition setting unit is transmitted to the user terminal 10. To notify by wireless communication. When the handover condition set by the condition setting unit is notified, the user terminal 10 determines whether or not the handover is necessary according to the handover condition. A handover request signal is transmitted to the station 20, and the handover control unit 24 performs handover control of the user terminal 10 in accordance with the handover request signal.

  The signal quality measuring unit 25 monitors the signal quality (for example, signal-to-noise power ratio (CN ratio)) when communication is performed with the terminal 10. The data amount measuring unit 26 monitors the data amount of data transmitted / received to / from the user terminal 10 via the base station 20. The protocol monitor unit 27 monitors the protocol type of the application used by the user terminal 10.

  The protocol monitor unit 27 determines the protocol type of the application used by the user terminal 10 by reading the information about the protocol stored in a part of the header part of the transmitted / received packet. Specifically, the TCP and UDP headers have a field in which the port number of the transmission destination is stored, and information on the protocol is stored in this field. The protocol monitor unit 27 determines the protocol of the application used by the user terminal 10 by reading the information in this field.

  The network unit 28 controls communication performed via the network 30. Although not shown, various servers such as a WWW server that enables browsing, a streaming server that enables streaming, and a mail server that enables transmission and reception of mail via the network 30 are connected to the network 30. ing.

  Next, a method for setting handover conditions for the user terminal 10 will be described. Here, although the user terminal 10 is located within the communication area of the base station 20, a case where the user terminal 10 moves outside the communication area of the base station 20 due to movement of the user terminal 10 will be described. FIG. 2 is a flowchart showing a method for setting handover conditions. Note that the process of the flowchart shown in FIG. 2 is executed by the base station 20 at predetermined time intervals.

  When the process is started, the base station 20 first determines whether or not it is connected to the user terminal 10 (step S11). If the determination result is “NO”, the process ends. On the other hand, if the determination result in step S11 is “YES”, the protocol monitor unit 27 monitors the protocol type of the application used by the user terminal 10. Further, the data amount measurement unit 26 measures the data amount of communication performed with the user terminal 10 (step S12). The signal quality measurement unit 25 also measures signal quality. Through the above processing, the base station 10 can grasp the type of application (type of protocol) used in the user terminal 10, the amount of data transmitted and received by the user terminal 10, and the signal quality.

  When the above processing is completed, a condition setting unit (not shown) provided in the handover control unit 24 determines a handover condition based on the monitoring result of the protocol monitoring unit 27 and the measurement result of the data amount measuring unit 26, If it is necessary to change the handover condition set in (2), a change process is performed (step S13).

  Here, a specific method for determining the handover condition will be described. For example, when streaming is being performed at the user terminal 10, it is better not to perform handover as much as possible so that video or audio is played continuously without interruption. On the other hand, in the case of browsing, if more data can be obtained at a time when the handover is performed, it is better to perform the handover. In addition, when performing file transfer by FTP, it is better to perform handover if the communication speed is improved by handover.

  For this reason, a condition setting unit (not shown) of the handover control unit 24 sets a signal quality threshold value indicating whether or not to perform handover for each protocol, and sets the handover condition by changing the threshold value for each protocol. decide. Specifically, a high threshold is set for a protocol that does not wish to be handed over as much as possible, and a low threshold is set for a protocol that should be handed over as much as possible. In the above example, a high threshold is set for the protocol used for streaming, and a low threshold is set for the protocol (HTTP) and FTP used for browsing. In other words, a protocol that does not want to be handed over (having a high threshold) is configured so that it is difficult to be handed over by setting a high threshold for the handover condition for a protocol that should be handed over as much as possible. .

  As described above, the degree to which the handover is not desired, that is, the degree to avoid the communication disconnection is different depending on the protocol. Therefore, the degree of communication disconnection (degree of disconnection avoidance) may be set for each protocol, and the handover condition threshold value may be set according to this degree. For example, a protocol used for streaming is set to have a high degree of disconnection avoidance, and a threshold value for handover conditions is set to be high.

  Taking streaming as an example, the signal speed of multimedia data sent according to the signal quality of the signal received by the user terminal 10 is different. For example, if the signal quality is higher than a certain quality, multimedia data is sent at 500 kbps (bit per second), and if the signal quality is lower than a certain quality, the multimedia data is sent at 128 kbps. In streaming, since it is not desired to cause video or audio to be interrupted, handover conditions are determined so as not to perform handover if the signal quality can maintain the current signal speed.

  As a method for setting the handover condition, a threshold of signal quality (for example, a signal-to-noise power ratio (CN ratio or SNR value)) indicating whether or not to perform a handover is set as the data amount or the transfer rate increases. While setting to a high value, you may make it set to a low value, so that the protocol with a high degree (disconnection avoidance degree) which wants to avoid the communication disconnection in the kind of application (protocol type) used with the user terminal 10 may be set. For example, the threshold value is set higher as the data amount (or transfer rate) increases, and the threshold value corresponding to various protocols with the same data amount (or transfer rate) is set lower as the protocol with a higher degree of disconnection avoidance.

  For protocols with low disconnect avoidance such as FTP, HTTP, POP / SMTP, etc., after setting the threshold of the handover condition to a predetermined threshold without changing it according to the data amount (or transfer rate) A handover condition may be set based on the signal quality relationship with the communication area (for example, handover is performed when the signal quality in the other communication area is higher than the signal quality in the current communication area). good. In this case, the threshold value of the signal quality that is set temporarily is set to a value that is higher than the threshold value that is set according to a protocol that has a high degree of disconnection avoidance such as RTSP or RTP in the entire data amount (or transfer rate). .

  When the setting and changing of the handover condition are completed, the base station 20 notifies the user terminal 10 of the handover condition via the antenna 21 (step S14). With the above processing, a series of processing ends. Note that the flowchart shown in FIG. 2 is executed again after a predetermined time has elapsed even after the processing shown in FIG.

  When the handover condition is notified from the base station 20, the user terminal 10 determines whether or not the handover condition is currently satisfied. If it is determined that the handover condition is satisfied, the user terminal 10 sends a handover request to the base station. 20 to send. When the handover request is received, the handover control unit 24 of the base station 20 performs a handover process for the user terminal 10. Since the handover process itself performed here is the same as the conventional one, the description thereof is omitted here. For example, when handover control is performed according to the reception strength at the user terminal 10, the handover process is performed. When it is not desired to set the handover condition high (the handover condition is increased), the reception intensity threshold value that is the handover condition may be set low.

  As described above, in this embodiment, since whether or not to perform handover is controlled according to the type of protocol, for example, it is possible to prevent audio interruption or to reduce the time required for file download. Can be made. Thereby, the convenience of the user who operates the user terminal 10 can be improved.

  The radio communication system and the radio base station apparatus according to the embodiment of the present invention have been described above. However, the present invention is not limited to the above embodiment, and can be freely changed within the scope of the present invention. For example, in the above-described embodiment, the handover control unit 24 performs the handover control of the user terminal when the handover request is transmitted from the user terminal 10, but the handover condition is satisfied on the base station 20 side. It may be determined whether or not it has been satisfied, and handover control may be performed when it is determined that the condition has been satisfied.

  In addition, although a condition setting unit for setting conditions for performing handover control, a signal quality measurement unit 25, a data amount measurement unit 26, a protocol monitor unit 27, and the like are arranged on the base station 20 side, these are arranged on the user terminal side. In addition, a handover request unit that makes a handover request to the base station according to the communication state of the radio communication with the base station is provided in the user terminal, and this handover request unit is used in the radio communication. You may comprise so that it may have a request condition setting means which sets the conditions which perform a hand-over request | requirement according to a protocol (communication procedure). In the above-described embodiment, signal quality such as reception intensity and error rate at the user terminal 10 is used as the handover condition. However, wireless communication performed between the base station and the user terminal (wireless communication terminal apparatus) is used. Any information indicating the communication state of communication may be used.

It is a block diagram which shows typically the whole structure of the communication system by one Embodiment of this invention, and the principal part structure of a radio base station apparatus. It is a flowchart which shows the setting method of handover conditions.

Explanation of symbols

10 User terminal (wireless communication terminal)
20 Base station (base station equipment)
22 Radio section (wireless communication means)
24 Handover control unit (handover control means)
25 Signal quality measurement unit (communication state detection means)
26 Data amount measuring unit (data amount detecting means)
27 Protocol monitor (communication procedure detection means)

Claims (7)

In a wireless communication system that detects a communication state of wireless communication performed between a base station and a wireless communication terminal, and hands over the wireless communication terminal according to the communication state,
Determining whether or not handover of the wireless communication terminal is necessary, and when determining that handover is necessary, handover control means for performing handover control;
Communication procedure detecting means for detecting a communication procedure used for the wireless communication between the wireless communication terminal and the base station;
The wireless communication system, wherein the handover control means includes condition setting means for setting a handover condition that is determined to be required for handover according to the communication procedure detected by the communication procedure detection means.   2. The wireless communication according to claim 1, wherein the condition setting unit sets a disconnection avoidance degree according to the communication procedure, and sets a higher threshold value for the handover condition for a communication procedure with a higher disconnection avoidance degree. system. Data amount detection means for detecting the amount of data communicated between the wireless communication terminal and the base station,
The wireless communication system according to claim 1, wherein the condition setting unit changes a handover condition set according to the communication procedure according to the data amount.   4. The wireless communication system according to claim 3, wherein the condition setting means sets a threshold value of the handover condition lower when the data amount is large than when the data amount is small. According to the wireless communication means for performing wireless communication with the wireless communication terminal, the communication state detection means for detecting the communication state of the wireless communication with the wireless communication terminal, and the communication state detected by the communication state detection means In a radio base station apparatus comprising a handover control means for handing over the radio communication terminal,
Comprising communication procedure detection means for detecting a communication procedure used for communication with the wireless communication terminal;
The radio base station apparatus, wherein the handover control means includes condition setting means for setting a condition for handing over the radio communication terminal according to the communication procedure detected by the communication procedure detecting means. Data amount detecting means for detecting the amount of data communicated with the wireless communication terminal,
The radio base station apparatus according to claim 5, wherein the condition setting means changes a handover condition set according to the communication procedure according to the data amount. A wireless communication means for performing wireless communication with the wireless base station apparatus; a communication state detecting means for detecting a communication state of the wireless communication with the wireless base station apparatus; and the communication state detected by the communication state detecting means. In response to a wireless communication terminal device comprising handover request means for performing a handover request in response,
Comprising communication procedure detecting means for detecting a communication procedure used for the wireless communication with the wireless base station device;
The wireless communication terminal apparatus, wherein the handover request means includes request condition setting means for setting a condition for performing the handover request according to the communication procedure detected by the communication procedure detection means.

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