JP2006191523A - Communication method, communication system, relay device, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication method, a communication system, a relay device, and a computer program for stabilizing a communication between the relay device to be used as an access point even when a communication state becomes bad and a terminal device to be used as a mobile IP telephone in a streaming communication such as an IP telephone etc. to be performed under wireless LAN environment. <P>SOLUTION: The relay device 1 assigns a communication band so as to make a communication speed to be low as much as possible when amount of data needed in a communication such as the streaming communication etc. is to be transmitted and received to and from each terminal device 2 by a communication speed set in every terminal device 2 using each communication band which is assigned to each terminal device 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a communication method using a plurality of terminal devices and a relay device that performs wireless communication with the terminal devices, a communication system to which the communication method is applied, a relay device used in the communication system, and the relay device In particular, the present invention relates to a communication method, a communication system, a relay device, and a computer program for suppressing deterioration in communication quality.

  In recent years, IP phones using VoIP (Voice over IP) have been rapidly spreading in general households and businesses, and more recently, portable IP phones using wireless LAN have begun to attract attention. Has begun to be introduced.

  In a communication system using wireless communication such as a wireless LAN, the same radio wave arrives at a plurality of terminal devices existing within a range where radio waves from a relay device called an access point reach. The relay device is controlled by a CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) method to prevent radio waves from a plurality of terminal devices from colliding with each other. The communication band is shared among the devices, and communication with a plurality of terminal devices is realized.

  In addition, in wireless LAN, a communication frame retransmission function is provided so that communication quality can be maintained and communication can be continued even when the communication state changes due to obstacles on the communication path, distances between relay devices and terminal devices, etc. It has a fallback communication function such as a link speed optimization function. The communication frame resend function checks the arrival status of the communication frame based on whether or not an ACK (Acknowledgement) frame is received at the MAC (Media Access Control) layer. If the ACK frame is not returned, the communication frame is resent. It is a function to do. The link speed optimization function is the data communication speed between the relay device and the terminal device while repeating the communication frame retransmission until the return of the ACK frame if the arrival of the communication frame cannot be confirmed even if the communication frame is retransmitted. This function reduces the link speed in stages. For example, in the wireless communication standard specified as IEEE 802.11b, the link speed is reduced from 11 Mbps to 5.5 Mbps, and further reduced to 2 Mbps and 1 Mbps. When the communication state improves due to the recovery of the radio wave state, the link speed is increased so as to improve the overall throughput.

  When the communication state deteriorates, a delay occurs because the communication frame is retransmitted by the communication frame retransmission function described above. The link speed is also reduced by the link speed optimization function, and communication frame retransmission is repeated until the link speed is changed from a high link speed to a low link speed at which stable communication is possible, causing a delay. . If the destination is not reached even after repeating the retransmission a certain number of times, the communication frame is discarded and packet loss occurs. Further, the link speed optimization function increases the link speed when the communication state is improved. When the communication state fluctuates, the link speed is repeatedly increased and decreased, and frame retransmission and delay occur repeatedly. In communication based on communication protocols such as FTP (File Transfer Protocol) and HTTP (Hyper Text Transfer Protocol), there is no problem with delay and packet loss. However, in streaming communication such as VoIP, communication quality such as sound quality and image quality deteriorates. Cause.

  When the link speed becomes low, in order to maintain the amount of data transferred per unit time in order to maintain streaming communication, the relay device increases the communication bandwidth allocated to the terminal device and increases the occupation rate of communication. Will be. For example, when the link speed decreases from 11 Mbps to 5.5 Mbps, a double communication band is allocated to transmit and receive a predetermined amount of data.

In Patent Document 1 below, in order to solve these problems, the link speed change cycle is changed for each link speed, thereby improving the efficiency of the link speed optimization process. If the link speed is changed at a common period for all link speeds, the change period must be increased in accordance with the lowest link speed that takes time to transmit the communication frame. Therefore, in the case of a high-speed link speed that can change the change cycle for each link speed and can easily transmit a communication frame in a short time because it is easily affected by the communication state such as the radio wave state, The link speed is finely adjusted with a short period, and the link speed is adjusted with a long period when the link speed is low, which is not easily influenced by the communication state and takes a long time to transmit the communication frame. In the communication method disclosed in Patent Document 1, in an environment where the communication state is small and the link speed is stable, the link speed can be increased efficiently, and the overall throughput can be improved. is there.
JP 2003-244105 A

  However, the conventional communication method disclosed in Patent Document 1 has a problem that the effect on the communication quality is small, for example, in an environment where the communication state changes abruptly and in an environment where the communication state is unstable. For example, if the terminal device moves from an area with a good communication state to an area with a poor communication state, and the communication state suddenly deteriorates and the link speed needs to be changed from 11 Mbps to 1 Mbps, the link speed control The communication frame retransmission is repeated while gradually reducing the speed, resulting in a delay. In addition, when the link speed fluctuates up and down in an environment where the communication state is unstable, retransmission of the communication frame is repeated and a delay occurs.

  The present invention has been made in view of such circumstances, and by setting the link speed in accordance with the use state of the communication band, it is difficult to be influenced by the communication state and minimizes the change in the link speed. Therefore, it is possible to prevent a communication frame from being retransmitted repeatedly and to achieve various effects thereby, a communication system to which the communication method is applied, a relay device used in the communication system, and the relay device. The purpose is to provide a computer program to be realized.

  The communication method according to the first invention uses a plurality of terminal devices and a relay device that performs wireless communication with the terminal devices, and the relay device occupies each terminal device from an available communication band. In the communication method for allocating a bandwidth and transmitting / receiving data to / from each terminal device at a communication speed set for each terminal device using the allocated communication band, the relay device is responsive to a usage state of the communication band. The communication speed with the terminal device is set.

  A communication system according to a second aspect of the present invention includes a plurality of terminal devices and a relay device that performs wireless communication with the terminal devices, and the relay device occupies each terminal device from an available communication band. In a communication system for allocating bandwidth and transmitting / receiving data to / from each terminal device at a communication speed set for each terminal device using the allocated communication band, the relay device is configured according to the usage status of the communication band. And a means for setting a communication speed with the terminal device.

  A relay device according to a third aspect of the present invention includes means for performing wireless communication with a plurality of terminal devices, assigns a communication band to be occupied by each terminal device from among usable communication bands, and uses the allocated communication band. In the relay device that transmits / receives data to / from each terminal device at a communication speed set for each terminal device, according to the means for recording the usage status of the communication band and the usage status of the recorded communication band, Setting means for setting a communication speed with the terminal device.

  A relay device according to a fourth aspect of the present invention includes means for performing wireless communication with a plurality of terminal devices, assigns a communication band to be occupied by each terminal device from among usable communication bands, and uses the allocated communication band. In a relay device that transmits / receives data to / from each terminal device at a communication speed set for each terminal device, means for recording the usage status of the communication band, and a usable communication bandwidth based on the recorded usage status A calculating means for calculating and a setting means for setting a communication speed as low as possible using an available communication band are provided.

  The relay device according to a fifth invention is the relay device according to the third invention or the fourth invention, according to the means for detecting a change in the number of the terminal devices serving as communication partners or a communication state with the terminal device, and the detected change, And a means for resetting the communication speed and reallocating the communication band of each terminal device.

  A relay device according to a sixth aspect of the present invention further comprises means for receiving a communication request from a terminal device that is not communicating in any of the third to fifth aspects, wherein the setting means is a source of the communication request. The communication speed of the communication with the terminal device is set.

  The relay device according to a seventh aspect of the present invention is based on the sixth aspect of the invention, based on the usable communication bandwidth calculated by the calculating means, whether or not it is possible to secure a communication bandwidth necessary for communication with the terminal device that is the transmission source of the communication request. A means for determining, a means for detecting a communication state with each communicating terminal device when it is determined that a communication band cannot be secured, and a terminal device for increasing the communication speed based on the detected communication state And a means for increasing the communication speed of the selected terminal device.

  A relay device according to an eighth aspect of the present invention is the relay device according to any one of the third to seventh aspects, wherein the means for detecting deterioration of the communication state of the terminal device with which communication is being performed and the means for detecting the communication state with another terminal device Based on the detected communication state, a means for selecting a terminal device for increasing the communication speed, a means for increasing the communication speed of the selected terminal device, and a terminal device whose communication state has deteriorated are retransmitted. It is characterized by further comprising means for allocating and means for reducing the communication speed of the terminal device whose communication state has deteriorated.

  In the relay device according to a ninth invention, in any one of the third to eighth inventions, the data transmitted and received between the relay device and the terminal device is data for streaming communication that requires transmission at a predetermined speed. It is characterized by.

  A computer program according to a tenth aspect of the invention assigns a communication band to be occupied by each terminal device from among usable communication bands to a computer having means for performing wireless communication with a plurality of terminal devices, and uses the assigned communication band Then, in a computer program for transmitting / receiving data to / from each terminal device at a communication speed set for each terminal device, a procedure for causing the computer to set a communication speed with the terminal device in accordance with a use state of a communication band Is executed.

  In the present invention, stable communication can be performed by setting a communication speed according to the use state of the communication band, and in particular by setting a low-speed communication speed that is not easily affected by a communication state such as a radio wave state. Is possible. In addition, since the number of times of changing the communication speed can be suppressed, the number of communication frame retransmissions at the time of changing the communication speed can be suppressed, so that it is possible to prevent delays associated with retransmission of communication frames. For this reason, since the communication band can be used effectively, it is possible to solve the shortage of band during communication.

  In the present invention, when a change in the number of terminal devices communicating with a relay device is detected, such as when a communication request is newly received from a terminal device, it is impossible to secure a communication band necessary for communication with the terminal device. It is possible to communicate with a large number of terminal devices by increasing the communication speed of a terminal device with a good communication state, supplementing the communication band, and enabling communication with a new terminal device. In addition, since the communication band is secured by increasing the communication speed of the terminal device having a good communication state, the communication state of the terminal device that has increased the communication speed is unlikely to become unstable, and thus the minimum Since the communication speed can be changed by retransmitting a limited number of communication frames, it is possible to minimize the delay associated with the retransmission of the communication frames.

  Furthermore, in the present invention, for example, when an operator operating a terminal device moves to an area where the radio wave condition is bad during a conversation and the communication state deteriorates, the communication speed of the terminal device with a good communication state is increased, By securing a stable communication and increasing the communication speed of a terminal device with a good communication state by reducing the communication speed of the terminal device whose communication state has deteriorated and expanding the communication band to be allocated Since the communication band is secured, it is unlikely that the communication state of the terminal device that has increased the communication speed becomes unstable, and therefore the communication speed can be changed with the minimum retransmission of communication frames. It is possible to minimize delays associated with retransmission of communication frames.

  In a communication method, a communication system, a relay device, and a computer program according to the present invention, a relay device using a relay device used as an access point and a plurality of terminal devices such as a portable IP phone that performs wireless communication with the relay device. Calculates a usable communication band based on the use state of the communication band, and sets a communication speed using the usable communication band, particularly a communication speed as low as possible.

  With this configuration, a low communication speed that is not easily affected by the communication state such as the radio wave state is maintained, so that an excellent effect is achieved such that stable communication can be performed. Also, for example, even if the communication state is good, the communication speed is not increased, and the number of times the communication speed is changed can be suppressed. Therefore, the number of communication frame retransmissions when the communication speed is changed can be suppressed. There are excellent effects such as being able to prevent delays associated with retransmission. In addition, since the communication band can be used effectively, an excellent effect is obtained such that it is possible to solve the shortage of the communication band during communication. In addition, packet loss due to repeated retransmission of communication frames can be reduced, and excellent effects such as prevention of voice quality deterioration can be obtained.

  Furthermore, in the present invention, when a change in the number of terminal devices communicating with a relay device is detected, such as when a communication request is newly received from a terminal device, it is impossible to secure a communication band necessary for communication with the terminal device. It is possible to communicate with a large number of terminal devices by increasing the communication speed of a terminal device with a good communication state, supplementing the communication band, and enabling communication with a new terminal device. In addition, since the communication band is secured by increasing the communication speed of the terminal device having a good communication state, the communication state of the terminal device having the increased communication speed is unlikely to be unstable, and therefore minimum Since the communication speed can be changed by retransmitting a limited number of communication frames, an excellent effect can be obtained, such as minimizing a delay associated with retransmission of the communication frame.

  In the present invention, for example, when an operator who operates the terminal device moves to an area where the radio wave condition is bad during communication and the communication state deteriorates, the communication speed of the terminal device with a good communication state is increased, and the communication bandwidth is increased. By securing a stable communication and increasing the communication speed of a terminal device with a good communication state by reducing the communication speed of the terminal device whose communication state has deteriorated and expanding the communication band to be allocated Since the bandwidth is secured, it is unlikely that the communication status of the terminal device that has increased the communication speed will be unstable, so the communication speed can be changed with a minimum of retransmission of communication frames. There are excellent effects such as minimizing delays associated with frame retransmission.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. FIG. 1 is an explanatory diagram conceptually showing a configuration example of a communication system according to the present invention. 1 is a relay device of the present invention using a communication computer that relays wireless communication as an access point. The relay device 1 includes a plurality of terminal devices 2, 2,. Wireless communication is performed by a method such as a CSMA / CA method. The relay device 1 is connected to a communication management device 3 using a stream server computer that communicates based on a communication protocol such as SIP (Session Initiation Protocol) for managing wireless communication with the terminal devices 2, 2,. The communication management device 3 manages each communication to be managed by identifying it with a communication identifier.

  Based on the management of the communication management device 3, a wireless LAN is realized between the relay device 1 and the terminal devices 2, 2,..., And the relay device 1 transfers to the terminal devices 2, 2,. Provides a streaming service such as VoIP in accordance with QoS (Quality of Service) technology.

  As detailed in Japanese Patent Application No. 2003-311033 filed by the applicant of the present application, in a wireless LAN, communication is performed by sharing a communication band among a plurality of terminal devices 2, 2,. In providing the streaming service, communication frame relay related to streaming communication managed by the communication management device 3 is preferentially performed. Further, the relay device 1 can dynamically assign the occupation rate of the communication band to each of the terminal devices 2, 2,..., And the communication speed (link) with each of the terminal devices 2, 2,. Speed) can also be set dynamically. The larger the communication band assigned to the terminal device 2 by the relay device 1 and the higher the communication speed to be set, the more data can be transmitted and received. However, when the external communication state such as the radio wave state is inferior, it is difficult to ensure communication quality for communication at a high communication speed.

  FIG. 2 is a block diagram illustrating a configuration example of various apparatuses included in the communication system of the present invention. The relay apparatus 1 includes a control means 10 such as a CPU for controlling the entire apparatus, a computer program 200 of the present invention, and a CD-ROM drive for reading various information from a recording medium 300 such as a CD-ROM recording various information such as data. Auxiliary storage means 11, recording means 12 such as a hard disk for recording various information read by the auxiliary storage means 11, and storage means 13 such as a RAM for temporarily storing information. Various information such as the computer program 200 and data of the present invention is read from the recording means 12 and stored in the storage means 13 such as a RAM for temporarily storing the information. Various procedures included in the computer program 200 are controlled by the control means 10. When executed, the communication computer operates as the relay device 1 of the present invention. Further, the relay device 1 includes a wireless communication unit 14 that performs wireless communication with the terminal devices 2, 2,... And a wired communication unit 15 that performs wired communication with the communication management device 3. A part of the recording area of the recording means 12 included in the relay device 1 is used as a management table 12a for managing information necessary for communication such as communication speed and communication band with each of the terminal devices 2, 2,. Note that a part of the recording area of the recording means 12 included in the relay apparatus 1 is not used as the management table 12a, but the recording area of the recording means of another apparatus connected to the relay apparatus 1 is used as the management table 12a. good.

  The terminal device 2 includes a control unit 20 that controls the entire apparatus, and a recording unit 21 such as a ROM or a RAM that records information such as computer programs and data necessary for various processes. Further, the control unit 20 controls a communication control unit 22 that controls communication, and the communication control unit 22 controls a communication unit 23 such as an antenna that transmits / receives data such as a digital signal required for telephone communication and its associated circuit. The control unit 20 controls the audio processing unit 26 that performs conversion processing of the analog audio signal output from the audio output unit 24 such as a speaker and the analog audio signal input from the audio input unit 25 such as a microphone. The conversion process by the audio processing unit 26 is a process of converting a digital signal into an analog audio signal to be output from the audio output unit 24, and an analog audio signal based on the audio input from the audio input unit 25 is converted into a digital signal. It is processing. Furthermore, the terminal device 2 receives input from the key input means 27 such as a push button that accepts key inputs such as alphanumeric characters and various commands under the control of the control means 20, and various information such as key input information and information to be transmitted / received. Necessary information is displayed on the display means 28 such as a liquid crystal display.

  FIG. 3 is an explanatory diagram conceptually showing an example of the recorded contents of the management table 12a provided in the relay apparatus 1 of the present invention. The management table 12a manages information related to preferentially relayed communication such as streaming communication among the relayed relay device 1. In the management table 12a, identification information for identifying the terminal device 2 that is the data transmission source and destination, status, data transfer amount, communication speed (link speed), frame retransmission average, occupied bandwidth, bandwidth occupancy, communication direction, etc. Various items are recorded as associated records. The recorded contents of the management table 12a illustrated in FIG. 3 include that the first terminal device 2 to which “192.168.254.10” is assigned as the IP address, the receiving port whose port number is “12345”, The second terminal apparatus 2 connected to the relay apparatus 1 at a communication speed of 11 Mbps using the transmission port having the port number “54321” and assigned with the IP address “192.168.254.11.” Using the transmission port with the port number “65432” and the reception port with the port number “12345”, the relay device 1 is connected to the relay device 1 at a communication speed of 5.5 Mbps, and the relay device 1 is the first terminal device. 2 illustrates a situation in which communication between the second terminal device 2 and the second terminal device 2 is relayed. The recorded contents of the management table 12a are updated sequentially.

  The identification information for identifying the terminal device 2 that is the data transmission source is an IP address such as “192.168.254.10” and a port number such as “54321” related to the first terminal device 2 that is the transmission source. It is information which shows. The identification information for identifying the terminal device 2 that is the data destination is information indicating an IP address such as “192.168.254.11” and a port number such as “65432” related to the second terminal device 2. .

  The state is information indicating a communication state such as “busy”. The data transfer amount is a value indicating the amount of data necessary for streaming communication such as “64 (kbit / sec)”. The communication speed is a link speed between the relay apparatus 1 and the terminal apparatus 2, and is “11 Mbps”, “5.5 Mbps”, “2 Mbps”, and “1 Mbps” in the wireless communication standard defined as IEEE802.11b. It is selected from the inside. The average of frame retransmission is a value obtained by averaging the number of repeated frame retransmissions for transmitting one frame, for example, for the 10 most recent transmission frames.

  The occupied band is a communication band corresponding to a data transfer amount used in wireless communication by each terminal device among transmission / reception capacities (communication bands) of data per unit time provided by the relay device 1, and is illustrated in FIG. In the management table 12a, the value calculated as the occupied bandwidth (Kbps) by the following equation 1 is shown. And the ratio of the communication band used with respect to the whole communication band is a band occupation rate (%). Needless to say, it may be indicated by time (msec) in the cycle or time occupancy (%).

  Occupied band = [data transfer amount × (11 / communication speed) + {occupied band in transmission waiting time + header size × (11 / communication speed) + occupied band in ACK} × number of transmission frames per second] × (frame Retransmission average +1) ...... Formula 1

  The communication direction is indicated as “terminal device → relay device” or “relay device → terminal device”.

  Next, processing of various devices in the communication system of the present invention will be described. In the communication system of the present invention, a communication band allocated exclusively for streaming communication is secured in advance in the entire communication band of the wireless LAN relayed by the relay device 1, and the total communication band used for streaming communication is the streaming communication. The communication speed is determined so as to be as low as possible within the range not exceeding the dedicated communication band, and the communication band is allocated. Specific processing is as follows.

  FIG. 4 is a flowchart showing a new call start process of the relay device 1 provided in the communication system of the present invention. The relay device 1 according to the present invention is configured so that the wireless communication unit 14 uses a communication request related to streaming communication from the terminal device 2 that is not communicating, under the control of the control unit 10 that executes the computer program 200 stored in the storage unit 13. (S101), based on the recorded contents of the management table 12a, calculate an unused communication band that is not occupied in the communication band reserved for streaming communication (S102), The communication speed when transmitting / receiving a predetermined amount of data, here, 64 kbit / s data within the calculated communication band is calculated (S103), and the calculated communication speed is the maximum value of the communication speed, here 11 Mbps or less. It is determined whether or not there is (S104). That is, through the processes in steps S102 to S104, it is determined whether or not it is possible to secure a communication band necessary for the terminal device 2 that has transmitted the communication request to communicate. In the following description, the terminal device 2 that is the transmission source of the communication request is indicated as a communication request terminal device 2a.

  In step S104, when it is determined that the communication speed calculated in step S103 is equal to or lower than the maximum value and it is possible to secure a communication band necessary for the communication requesting terminal device 2a to communicate (S104: YES), relaying Under the control of the control means 10, the device 1 sets a communication speed as low as possible that falls within the assignable communication band for the terminal device 2 that is the transmission source of the communication request (S105). Accordingly, a communication band is allocated (S106), and communication at a speed set in the allocated communication band is started (S107). Information necessary for communication such as the assigned communication band and the set communication speed is recorded in the management table 12a.

  When it is determined in step S104 that the communication speed calculated in step S103 is greater than the maximum value and it is impossible to secure a communication band necessary for communication by the communication requesting terminal device 2a (S104: NO), the relay device 1 detects a communication state with each of the terminal devices 2, 2,... Communicating with each other under the control of the control unit 10 (S 108), and sets the terminal device 2 to increase the communication speed based on the detected communication state. Select (S109). The selection based on the communication state indicates that the terminal device 2 having a good communication state is selected from the frame retransmission rate, the communication speed, and the radio wave intensity related to the communication with each terminal device 2, 2,. Specifically, the terminal device 2 with the lowest frame retransmission rate is selected as the terminal device 2 with the best communication state, and when there are a plurality of terminal devices 2 with the lowest frame retransmission rate, the communication speed is the lowest. When the terminal device 2 with the lowest communication speed is selected as the terminal device 2 with the lowest communication speed and there are a plurality of terminal devices 2 with the lowest communication speed, the terminal device 2 with the highest radio wave intensity is selected as the most communication state. Is selected as a good terminal device 2. That is, the communication state is determined based on the priority order of the frame retransmission rate, the communication speed, and the radio wave intensity. .. May be selected as the terminal device 2 for increasing the communication speed. In the following description, the terminal device 2 selected as the terminal device 2 for increasing the communication speed is shown as the selected terminal device 2b.

  Then, the relay device 1 calculates a secure communication bandwidth (a communication bandwidth that is unused and can be used) when the communication speed of the selected terminal device 2b is increased under the control of the control unit 10 (S110), and secures it. Within the possible communication band, the communication speed when the communication requesting terminal device 2a transmits and receives a predetermined amount of data necessary for streaming communication is calculated (S111), and whether or not the calculated communication speed is below the maximum value is calculated. Determine (S112). That is, through the processing of steps S110 to S112, it is determined whether or not it is possible to secure a communication band necessary for the terminal device 2 that is the transmission source of the communication request to communicate.

  In step S112, when it is determined that the communication speed calculated in step S111 is equal to or lower than the maximum value and it is possible to secure a communication band necessary for the communication requesting terminal device 2a to communicate (S112: YES), relaying The device 1 increases the communication speed of the selected terminal device 2b under the control of the control means 10 (S113), reallocates the communication band in accordance with the increased communication speed (S114), and uses the reassigned communication band. Communication at the increased speed is started (S115). By reallocating the communication band according to the increased communication speed, the communication band that can be allocated to the communication requesting terminal device 2a is expanded. Furthermore, the relay device 1 controls the control means 10 so that the communication bandwidth to be assigned to the communication requesting terminal device 2a is as low as possible among the communication speeds that fall within the expanded assignable communication bandwidth. Is selected and set (S116), a communication band is assigned according to the set communication speed (S117), and communication at a speed set in the assigned communication band is started (S118). Information necessary for communication such as the assigned communication band and the set communication speed is recorded in the management table 12a.

  When it is determined in step S112 that the communication speed calculated in step S111 is greater than the maximum value and it is impossible to secure a communication band necessary for communication by the communication requesting terminal device 2a (S112: NO), the relay device 1 transmits information indicating that it is out of the communication range from the wireless communication unit 14 to the communication requesting terminal device 2a under the control of the control unit 10, and rejects the start of communication (S119). Even if it is determined in step S112 that the communication band can be secured, if the communication state with the communication requesting terminal device 2a is previously known to be inferior, the start of communication is rejected. In addition, as a process of notifying the start of communication in step S119, the notification is not sent from the relay device 1 to the communication request terminal device 2a by wireless communication, but is notified to the communication request terminal device 2a via the relay device 1. Anyway. That is, as the processing of step S119, the relay device 1 notifies the communication management device 3 of the identification information of the communication requesting device 2a and the information indicating that it is out of the communication area from the wired communication means 15, and the communication management device 3 receives the information. You may make it refuse communication start by transmitting the information which shows out of communication range to the communication request | requirement terminal 2a identified by identification information.

  FIG. 5 is a flowchart showing a communication state improvement process of the relay device 1 included in the communication system of the present invention. The relay device 1 according to the present invention causes the communication state of one terminal device 2 communicating with the wireless communication unit 14 to deteriorate due to the control of the control unit 10 that executes the computer program 200 stored in the storage unit 13. If detected (S201), based on the recorded contents of the management table 12a, an unused communication band that is not occupied in the communication band reserved for streaming communication and can be used is calculated (S202). The detection of the deterioration of the communication state of the terminal device 2 in step S201 is detected based on the frame retransmission rate and the radio wave intensity recorded in the management table 12a. When the frame retransmission rate exceeds a predetermined value or rapidly deteriorates, or when the radio wave intensity becomes lower than a predetermined value or rapidly deteriorates, it is detected that the communication state has deteriorated. In the following description, the terminal device 2 whose communication state has deteriorated is shown as a state deterioration terminal device 2c.

  The relay device 1 of the present invention calculates the communication speed when the state deterioration terminal device 2c transmits and receives a predetermined amount of data necessary for streaming communication within the calculated unused communication band under the control of the control means ( S203), it is determined whether or not the calculated communication speed is equal to or lower than the communication speed when the communication speed of the state deterioration terminal device 2c is reduced (S204).

  In step S204, when it is determined that the communication speed calculated in step S203 is higher than the communication speed after the speed reduction (S204: NO), the relay device 1 communicates under communication under the control of the control means 10. .. Are detected (S205), and the terminal device 2 that increases the communication speed is selected based on the detected communication state (S206). In the following description, the selected terminal device 2 is shown as a selected terminal device 2d.

  Then, the relay device 1 calculates a reservable communication band (unused communication band) when the communication speed of the selected terminal device 2d is increased under the control of the control unit 10 (S207), and reservable communication. Within the band, the communication speed when the state deterioration terminal device 2c transmits and receives a predetermined amount of data necessary for streaming communication is calculated (S208), and the calculated communication speed decreases the communication speed of the state deterioration terminal device 2c. It is determined whether or not the communication speed is equal to or lower than the case (S209).

  In step S209, when it is determined that the communication speed calculated in step S208 is equal to or lower than the communication speed after the reduction (S209: YES), the relay device 1 controls the selected terminal device 2d under the control of the control means 10. The communication speed is increased (S210), the communication band is reassigned according to the increased communication speed (S211), and the communication at the speed increased in the reassigned communication band is started (S212). Furthermore, the relay device 1 selects and sets a communication speed that is as low as possible within the expanded allocatable communication bandwidth for the state deterioration terminal device 2d under the control of the control means 10 ( S213), a communication band is allocated according to the set communication speed (S214), and communication at a speed set in the allocated communication band is started (S215). Information necessary for communication such as the assigned communication band and the set communication speed is recorded in the management table 12a.

  If it is determined in step S204 that the communication speed calculated in step S203 is equal to or lower than the communication speed after the speed reduction (S204: YES), the process proceeds to step S213, and the subsequent processing is executed.

  In step S209, when it is determined that the communication speed calculated in step S208 is higher than the communication speed after the reduction (S209: NO), the relay device 1 changes the state from the wireless communication means 14 under the control of the control means 10. Information indicating that it is out of the communication range is transmitted to the deteriorated terminal device 2c, and the communication is forcibly terminated (S216). Even when the communication speed of the state deterioration terminal device 2c is reduced, if the communication state is inferior, the communication state is detected again by the process of step S201. Further, even when the communication state of the terminal device 2 whose communication speed is increased due to the new call start process or the communication state improvement process shown using the flowchart of FIG. 4, the process of step S201 of the communication state improvement process Therefore, it is detected as a deterioration of the communication state. Furthermore, during the above-described processing, there may be a situation where the communication band for streaming communication is instantaneously insufficient until the communication band is secured. However, as a response to such a situation, the priority is low. The communication band for data communication may be temporarily used for communication, or a spare communication band may be secured in advance.

  FIG. 6 is a flowchart showing a communication speed reduction process of the relay device 1 included in the communication system of the present invention. When the relay device 1 of the present invention detects the end of communication of the terminal device 2 communicating with the wireless communication unit 14 under the control of the control unit 10 that executes the computer program 200 stored in the storage unit 13 (S301). ), The communication state with each of the terminal devices 2, 2,... That are communicating is detected (S302), and the terminal device 2 that reduces the communication speed is selected based on the detected communication state (S303). The selection based on the communication state indicates that the terminal device 2 having a poor communication state is selected from the frame retransmission rate, the communication speed, and the radio wave intensity related to the communication with each of the terminal devices 2, 2,. Specifically, the terminal device 2 with the highest frame retransmission rate is selected as the terminal device 2 with the worst communication state, and when there are a plurality of terminal devices 2 with the highest frame retransmission rate, the highest communication speed among them. When the terminal device 2 having the highest communication speed is selected as the terminal device 2 having the highest communication speed and there are a plurality of terminal devices 2 having the highest communication speed, the terminal device 2 having the weakest radio wave intensity is selected. Is selected as a poor terminal device 2. That is, the communication state is determined based on the priority order of the frame retransmission rate, the communication speed, and the radio wave intensity. In the following description, the terminal device 2 selected as the terminal device 2 for reducing the communication speed is shown as the selected terminal device 2e.

  Then, the relay device 1 calculates the usable unused communication band expanded by the termination of the terminal device 2 under the control of the control means 10 (S304), and the selected terminal device 2e is within the reservable communication band. When the communication speed is reduced, a communication band necessary for transmitting and receiving a predetermined amount of data necessary for streaming communication is calculated (S305), and whether or not the calculated communication band is equal to or less than an unused communication band. Is determined (S306).

  In step S306, when it is determined that the communication band calculated in step S305 is equal to or less than the unused communication band (S306: YES), the relay device 1 controls the communication of the selected terminal device 2e under the control of the control unit 10. The speed is reduced as much as possible (S307), the communication band is reassigned according to the reduced communication speed (S308), and communication at the speed reduced in the reassigned communication band is started (S309). ). Information necessary for communication such as the assigned communication band and the set communication speed is recorded in the management table 12a.

  In step S306, when it is determined that the communication band calculated in step S305 is larger than the unused communication band (S306: NO), the communication speed is not reduced, and the process ends.

  In the above-described embodiment, the communication speed set according to the communication status is set as low as possible. However, the present invention is not limited to this, and communication can be stabilized. A mode in which an optimum possible communication speed is appropriately set may be employed. Specifically, when setting the communication speed, the average value of the communication speeds of all the terminal devices currently in communication is calculated, and the calculated average value is set as the communication speed. If the number of terminal devices that are communicating is large and the communication band tends to be insufficient, the average value of the communication speed is high, and if the number of terminal devices that are communicating is small and the communication band is large, the average of the communication speed The value tends to be low. Therefore, by setting the communication speed based on the average value of the communication speed when the communication speed is reduced at the start of communication, at the end of communication, etc., when the number of terminal devices that are communicating is large and the communication band tends to be insufficient, The communication speed that is set increases, and when the number of terminal devices that are communicating is small and there is a margin in the communication band, the communication speed that is set decreases. By setting the communication speed in this way, the communication speed of the terminal device can be increased when starting a new communication or when the communication situation deteriorates, compared to setting the communication speed as low as possible. Since opportunities for speeding up can be reduced, communication can be stabilized.

  Further, in the above-described embodiment, the form applied to the IP telephone based on VoIP is shown. However, the present invention is not limited to this, and can be applied to various wireless communications in which a data transfer amount of a predetermined amount or more should be secured. is there.

  Regarding the above embodiment, the following additional notes are disclosed.

(Appendix 1) Using a plurality of terminal devices and a relay device that performs wireless communication with the terminal device, the relay device allocates and allocates a communication band to be occupied by each terminal device from among available communication bands In the communication method for transmitting / receiving data to / from each terminal device at a communication speed set for each terminal device using a determined communication band, the relay device communicates with the terminal device according to the usage status of the communication band. A communication method characterized in that the communication speed is set.
(Appendix 2) Using a plurality of terminal devices and a relay device that performs wireless communication with the terminal device, the relay device allocates and allocates a communication band to be occupied by each terminal device from among available communication bands In the communication method for transmitting / receiving data to / from each terminal device at a communication speed set for each terminal device using the communication band, the relay device sets a usable communication band based on the usage status of the communication band. A communication method characterized by calculating and setting a communication speed as low as possible using an available communication band.
(Supplementary Note 3) A plurality of terminal devices and a relay device that performs wireless communication with the terminal devices, and the relay device allocates and allocates a communication band to be occupied by each terminal device from among usable communication bands. In a communication system that transmits / receives data to / from each terminal device at a communication speed set for each terminal device using a communication band, the relay device communicates with the terminal device according to a usage state of the communication band. A communication system comprising means for setting the communication speed. (Supplementary Note 4) Provided with means for performing wireless communication with a plurality of terminal devices, assigning a communication band to be occupied by each terminal device from among usable communication bands, and using the allocated communication bandwidth for each of the terminal devices In a relay device that transmits / receives data to / from each terminal device at a set communication speed, means for recording a communication band usage status and communication with the terminal device according to the recorded communication bandwidth usage status A relay device comprising setting means for setting a speed.
(Additional remark 5) It is provided with the means to perform radio | wireless communication with a some terminal device, allocates the communication band which each terminal device occupies from the available communication band, and uses the allocated communication band for every said terminal device In a relay device that transmits / receives data to / from each terminal device at a set communication speed, means for recording a communication band usage status, and calculation means for calculating a usable communication bandwidth based on the recorded usage status And a setting means for setting a communication speed as low as possible using a usable communication band.
(Appendix 6) Means for detecting a change in the number of the terminal devices serving as communication partners or a communication state with the terminal device, and resetting of the communication speed of each terminal device and the communication band in accordance with the detected change The relay device according to appendix 4 or appendix 5, further comprising means for performing reallocation.
(Additional remark 7) It further has a means to receive the communication request from the terminal device which is not communicating, The said setting means is comprised so that the communication speed of communication with the terminal device of the transmission origin of a communication request may be set. The relay device according to any one of appendix 4 to appendix 6, characterized in that.
(Supplementary note 8) Based on the usable communication bandwidth calculated by the calculating means, means for determining whether or not to secure a communication band necessary for communication with the terminal device that is the transmission source of the communication request; Means for detecting a communication state with each communicating terminal device when it is determined to be impossible, a means for selecting a terminal device for increasing the communication speed based on the detected communication state, and the selected terminal device The relay device according to appendix 7, further comprising: a means for increasing the communication speed.
(Supplementary Note 9) Means for detecting deterioration of communication state of communicating terminal device, means for detecting communication state with other terminal device, and terminal for increasing communication speed based on detected communication state A means for selecting a device, a means for increasing the communication speed of the selected terminal device, a means for reallocating a communication band to a terminal device whose communication state has deteriorated, and a communication speed of the terminal device whose communication state has deteriorated is reduced. The relay device according to any one of appendix 4 to appendix 8, further comprising:
(Supplementary note 10) The relay device according to any one of supplementary notes 4 to 9, wherein data transmitted and received between the relay device and the terminal device is data for streaming communication that requires transmission at a predetermined speed. .
(Supplementary note 11) The relay device according to any one of supplementary notes 4 to 10, further comprising a table that records a communication occupation rate, a communication speed, and a data amount to be transmitted and received in association with a terminal device that is a communication partner. .
(Supplementary note 12) A communication band to be occupied by each terminal device is allocated from among usable communication bands to a computer including means for performing wireless communication with a plurality of terminal devices, and the terminal device is allocated using the allocated communication band In a computer program for transmitting / receiving data to / from each terminal device at a communication speed set for each, causing the computer to execute a procedure for setting the communication speed with the terminal device according to the use state of the communication band. A featured computer program.
(Supplementary note 13) A communication band to be occupied by each terminal device is allocated from among usable communication bands to a computer having means for performing wireless communication with a plurality of terminal devices, and the terminal device is allocated using the allocated communication band In a computer program for transmitting / receiving data to / from each terminal device at a communication speed set for each, a procedure for causing the computer to calculate a usable communication band based on a use state of the communication band and a usable communication band are used. And a procedure for setting a communication speed as low as possible.

It is explanatory drawing which shows notionally the structural example of the communication system of this invention. It is a block diagram which shows the structural example of the various apparatuses with which the communication system of this invention is provided. It is explanatory drawing which shows notionally an example of the content of recording of the management table with which the relay apparatus of this invention is provided. It is a flowchart which shows the new call start process of the relay apparatus with which the communication system of this invention is provided. It is a flowchart which shows the communication state improvement process of the relay apparatus with which the communication system of this invention is provided. It is a flowchart which shows the communication speed reduction process of the relay apparatus with which the communication system of this invention is provided.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Relay device 2 Terminal device 3 Communication management device 200 Computer program 300 Recording medium

Claims (10)

Using a plurality of terminal devices and a relay device that performs wireless communication with the terminal device, the relay device allocates a communication band to be occupied by each terminal device from among usable communication bands, and assigns the allocated communication band to the terminal device. In a communication method for transmitting and receiving data with each terminal device at a communication speed set for each terminal device using,
The relay apparatus sets a communication speed with the terminal device according to a use state of a communication band. A plurality of terminal devices, and a relay device that performs wireless communication with the terminal device, the relay device assigning a communication band to be occupied by each terminal device from among available communication bands, and assigning the allocated communication band In a communication system that transmits and receives data with each terminal device at a communication speed set for each terminal device using,
The said relay apparatus is provided with a means to set the communication speed with the said terminal device according to the use condition of a communication band, The communication system characterized by the above-mentioned. Communication that includes means for performing wireless communication with a plurality of terminal devices, allocates a communication band to be occupied by each terminal device from among available communication bands, and is set for each terminal device using the allocated communication band In a relay device that transmits / receives data to / from each terminal device at a speed,
Means for recording the usage status of the communication band;
A relay device comprising: a setting unit configured to set a communication speed with the terminal device according to a use situation of a recorded communication band. Communication that includes means for performing wireless communication with a plurality of terminal devices, allocates a communication band to be occupied by each terminal device from among available communication bands, and is set for each terminal device using the allocated communication band In a relay device that transmits / receives data to / from each terminal device at a speed,
Means for recording the usage status of the communication band;
A calculation means for calculating a usable communication band based on the recorded use situation;
A relay device comprising: setting means for setting a communication speed as low as possible using an available communication band. Means for detecting a change in the number of the terminal devices serving as communication partners or a communication state with the terminal devices;
The relay apparatus according to claim 3, further comprising means for resetting a communication speed and reallocating a communication band of each terminal apparatus according to the detected change. A means for receiving a communication request from a terminal device that is not communicating;
The relay device according to any one of claims 3 to 5, wherein the setting unit is configured to set a communication speed of communication with a terminal device that is a transmission source of a communication request. Means for determining whether or not it is possible to secure a communication band necessary for communication with the terminal device that is the transmission source of the communication request, based on the usable communication band calculated by the calculation means;
Means for detecting a communication state with each terminal device in communication when it is determined that the communication band cannot be secured;
Means for selecting a terminal device for increasing the communication speed based on the detected communication state;
The relay apparatus according to claim 6, further comprising: means for increasing a communication speed of the selected terminal device. Means for detecting a deterioration in the communication state of the terminal device in communication;
Means for detecting a communication state with another terminal device;
Means for selecting a terminal device for increasing the communication speed based on the detected communication state;
Means for increasing the communication speed of the selected terminal device;
8. The method according to claim 3, further comprising: means for reallocating a communication band to a terminal apparatus whose communication state has deteriorated; and means for reducing the communication speed of the terminal apparatus whose communication state has deteriorated. A relay device according to any one of the above.   9. The relay apparatus according to claim 3, wherein the data transmitted / received between the relay apparatus and the terminal apparatus is data for streaming communication that requires transmission at a predetermined speed. A communication band to be occupied by each terminal device is assigned to a computer having means for performing wireless communication with a plurality of terminal devices, and is set for each terminal device using the allocated communication band. In a computer program for transmitting / receiving data to / from each terminal device at a communication speed of
A computer program for causing a computer to execute a procedure for setting a communication speed with the terminal device in accordance with a use state of a communication band.

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