JP2008113204A - Communication controller, wireless communication apparatus, communication control method and wireless communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication controller which can detect the narrowing of a transmission band quickly and accurately and can reduce the number of packets which are not reproduced but discarded due to a delay of an arriving time when communication is performed while complementing a band deficient in one wireless communication route by using the other wireless communication route, and to provide a wireless communication apparatus, a communication control method and a wireless communication method. <P>SOLUTION: A switching server 100 and an MN 300 create a transmission band control message based on a VoIP packet received in a monitor period dependent on the band allocation rate of VoIP packet for the up direction and the down direction of wireless IP networks 10A and 10B and transmit the transmission band control message to the transmission side, thus controlling the corresponding transmission bands of the wireless IP networks 10A and 10B on the transmission side. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the present invention, a plurality of different wireless communication paths can be used, and the bandwidth that is lacking in one wireless communication path is supplemented by using other wireless communication paths with respect to the required bandwidth of the application having real-time characteristics to be used. The present invention relates to a novel communication control device, a wireless communication device, a communication control method, and a wireless communication method that can execute communication.

  For example, in a wireless communication network using an Internet protocol (IP) group (hereinafter, appropriately abbreviated as “wireless IP network”), so-called mobile IP is defined in order to improve mobility of a wireless communication device (for example, Non-patent document 1).

In the mobile IP, a care-of IP address (Care of Address) that is dynamically assigned according to the position of the wireless communication device is used.
C. Perkins, “IP Mobility Support (RFC2002)”, [online], October 1996, IETF, [March 15, 2006 search], Internet <URL: http: //www.ietf.org / rfc /rfc2002.txt

  By the way, recently, an environment in which a wireless communication apparatus can use a plurality of wireless IP networks (for example, a mobile phone network and a wireless LAN network) is being provided.

  If such an environment is provided, when the bandwidth of the wireless IP network used for ongoing communication is insufficient, a plurality of wireless IPs such that the insufficient bandwidth is supplemented by another wireless IP network. It is conceivable to use the network simultaneously.

  However, when one wireless IP network is used as a master route, another wireless IP network is used as a slave route, and the bandwidth that is insufficient in the master route is supplemented by the slave route, the allowable bandwidth in the slave route satisfies the bandwidth that needs to be supplemented. Otherwise, the packets corresponding to the supplementary bandwidth to be transmitted to the slave path are temporarily stored in a buffer existing on the path and sequentially transmitted because the bandwidth is insufficient. For this reason, on the receiving side, a delay occurs between the packet received via the master path and the packet received via the slave path. This delay appears as an overtaking of SN (sequence number) in VoIP packets.

  In real-time applications such as VoIP, a jitter buffer is provided in order to absorb the overtaking of packets in the network. However, when the delay between paths increases and exceeds the buffer capacity of the jitter buffer, the delay exceeds the capacity. Even if the packet is received, it is discarded. For this reason, if the transmission of packets exceeding the allowable bandwidth is continued, the amount of packets accumulated in the buffer existing on the path will increase (up to the limit amount of the buffer), resulting in a delay difference corresponding to the accumulation amount. Eventually, all the packets sent out as a complement will be discarded at the receiving end.

  Particularly in wireless communication paths, the allowable bandwidth depends on changes in the propagation environment such as fading, so even if the allowable bandwidth of the slave path is sufficient at the beginning of communication, the bandwidth becomes narrow due to subsequent deterioration of the propagation environment. The above phenomenon tends to occur. In order to avoid this, the fluctuation of the allowable bandwidth of the slave path to be complemented, especially the narrowing of the bandwidth, is accurately detected to determine whether the current transmission bandwidth (bandwidth allocation ratio) is appropriate or not. Therefore, it is necessary to avoid complementation exceeding the allowable bandwidth.

  In addition, since the variation in the allowable bandwidth also occurs on the master path side, the transmission bandwidth (bandwidth allocation ratio) at the present time is also accurately detected in the master route by accurately detecting the variation in the allowable bandwidth, particularly the narrowing of the bandwidth. Therefore, it is necessary to determine whether or not the packet is appropriate and avoid packet transmission exceeding the allowable bandwidth.

  As a method for determining such a transmission band, for example, a window Ts of a predetermined period (for example, 500 ms) is set for each communication path to monitor the number of received packets, and the number of received packets is a bandwidth allocation rate in the communication path. When the number of packets (threshold value) is less than the expected number, it is possible to detect that the allowable bandwidth of the communication path is narrowed and determine that the transmission bandwidth is inappropriate (bad).

  However, in this case, the residence delay time varies depending on the timing of the window Ts. For example, when the application is VoIP and VoIP packets are sent at intervals of 20 ms as shown in FIG. 9, it is assumed that the allowable bandwidth of the communication path is narrowed to 50% at time t1. In FIG. 9, the horizontal axis represents time t, and the vertical axis represents the sequence number (SN) of the VoIP packet. Here, in order to simplify the description, the bandwidth allocation rate in the communication path is shown as 100% with respect to the requested bandwidth of the VoIP application. In FIG. 9, Dp indicates a potential delay time (in this case, 80 ms) from the transmission timing of the VoIP packet to the ideal reception timing in the communication path, and Tb is an allowable reproduction time from the transmission timing of the VoIP packet. (In this case, 200 ms), and Ds indicates a stay delay time.

  In FIG. 9, when the number of received packets in the window Ts up to time t1 is monitored, a decrease in the number of received packets is not observed, but when the number of received packets in the window Ts between (t2 and t1) is monitored at time t2, The number of received packets is halved to 12 packets with respect to the assumed number of received packets (500 ms / 20 ms = 25 packets). For this reason, it is necessary to reduce the bandwidth allocation rate to the communication path (lower the transmission rate). In this case, the VoIP packet (SN4) transmitted at time t2 is received at time t4. Therefore, a residence delay time Ds of 580 ms (= t4−t3) occurs with respect to the ideal reception time t3.

  For this reason, assuming that a VoIP packet (a VoIP packet exceeding the reproduction allowable line) received exceeding the reproduction allowable time Tb of 200 ms from the transmission timing is discarded (excluded from reproduction), in this case, in FIG. Of the 25 packets transmitted during the window Ts, 23 filled VoIP packets are discarded without contributing to reproduction.

  As described above, the number of received packets in the window Ts is monitored, and when the number of received packets is smaller than the threshold, if it is detected that the allowable bandwidth of the communication path is narrowed, the timing of the window Ts that is the monitoring period is reached. Depending on this, the residence delay time varies. Therefore, depending on the timing of the window Ts, there is a concern that most of the packets transmitted during the window Ts are discarded without contributing to reproduction.

  As a method of reducing the number of discarded packets, it is conceivable to shorten the stay delay time Ds by setting the window Ts short in FIG. However, the number of received packets in the window Ts is proportional to the bandwidth allocation rate in the communication path. The lower the bandwidth allocation rate, the smaller the number of received packets.

  For this reason, when the window Ts is set to a short period, it becomes difficult to set a threshold value particularly when the bandwidth allocation rate is low, and there is a concern that narrowing of the bandwidth cannot be accurately detected.

  Accordingly, an object of the present invention made in view of such circumstances is that a plurality of different wireless communication paths can be used, and communication can be performed while supplementing the bandwidth shortage in one wireless communication path using another wireless communication path. In execution, a communication control device, a wireless communication device, and a communication device that can quickly and accurately detect narrowing of the transmission bandwidth and can effectively reduce the number of packets discarded without being reproduced due to arrival time delay. A control method and a wireless communication method are provided.

The invention according to claim 1, which achieves the above object, allows a plurality of different wireless communication paths to be used with a wireless communication apparatus, and provides one wireless communication path for a requested bandwidth of an application having real-time characteristics to be used. A communication control device for controlling the communication between the wireless communication device and the communication destination by supplementing the insufficient bandwidth with another wireless communication path,
First uplink bandwidth allocation ratio determining means for determining a bandwidth allocation ratio of a packet transmitted by the wireless communication apparatus to the one wireless communication path;
The one wireless communication based on a packet received through the one wireless communication path within a first uplink monitoring period according to the bandwidth allocation rate determined by the first uplink bandwidth allocation rate determining means. First upstream bandwidth state determination means for determining upstream bandwidth state in the path;
Based on the determination result of the first uplink band state determination unit, the wireless communication apparatus transmits first uplink transmission control information for controlling a transmission band of a packet transmitted by the wireless communication apparatus to the one wireless communication path. First uplink transmission control means for transmitting;
A second upstream bandwidth allocation ratio determining means for determining a bandwidth allocation ratio of a packet transmitted by the wireless communication apparatus to the other wireless communication path;
Based on the packet received through the other wireless communication path within the second uplink monitoring period according to the bandwidth allocation rate determined by the second uplink bandwidth allocation rate determining means, the other wireless communication A second upstream bandwidth state determination means for determining an upstream bandwidth state in the path;
Based on the determination result of the second uplink band state determination means, the wireless communication apparatus transmits second uplink transmission control information for controlling a transmission band of a packet transmitted by the wireless communication apparatus to the other wireless communication path. Second uplink transmission control means for transmitting;
It is characterized by having.

The invention according to claim 2 is the communication control apparatus according to claim 1,
The first uplink monitoring period is a transmission period of a predetermined number of sequential packets transmitted by the wireless communication apparatus to the one wireless communication path at a bandwidth allocation rate determined by the first uplink bandwidth allocation rate determining unit. Corresponding to
The second uplink monitoring period is a transmission period of a predetermined number of sequential packets transmitted by the wireless communication apparatus to the other wireless communication path at the bandwidth allocation rate determined by the second uplink bandwidth allocation rate determining unit. Corresponding to
It is characterized by this.

The invention according to claim 3 is the communication control apparatus according to claim 1 or 2,
The first uplink bandwidth state determination means calculates a displacement degree of a reception timing of a packet received via the one wireless communication path within the first uplink monitoring period, and calculates the calculated displacement degree. Based on the comparison with the threshold corresponding to the bandwidth allocation rate determined by the first uplink bandwidth allocation rate determining means, the upstream bandwidth state in the one wireless communication path is determined,
The second uplink bandwidth state determining means calculates a displacement degree of a reception timing of a packet received through the other wireless communication path within the second uplink monitoring period, and calculates the calculated displacement degree. And determining the upstream bandwidth state in the other wireless communication path based on a comparison between the second upstream bandwidth allocation rate determining means and a threshold corresponding to the bandwidth allocation rate determined by the second uplink bandwidth allocation rate determining means,
It is characterized by this.

Furthermore, in the invention according to claim 4 that achieves the above object, a plurality of different wireless communication paths can be used with the communication control apparatus, and one wireless is provided for a required bandwidth of an application having real-time characteristics to be used. A wireless communication device that complements a bandwidth shortage in a communication path using another wireless communication route and wirelessly communicates with a communication destination via the communication control device,
First downlink bandwidth allocation ratio determining means for determining a bandwidth allocation ratio of a packet transmitted by the communication control device to the one wireless communication path;
The one wireless communication based on a packet received via the one wireless communication path within a first downlink monitoring period according to the bandwidth allocation rate determined by the first downlink bandwidth allocation rate determining means. First downstream band state determination means for determining a downstream band state in the path;
Based on the determination result of the first downlink band state determination unit, the communication control apparatus transmits first downlink transmission control information for controlling a transmission band of a packet transmitted to the one wireless communication path to the communication control apparatus. First downlink transmission control means for transmitting;
A second downlink bandwidth allocation ratio determining means for determining a bandwidth allocation ratio of a packet transmitted by the communication control device to the other wireless communication path;
Based on the packet received via the other wireless communication path within the second downlink monitoring period corresponding to the bandwidth allocation rate determined by the second downlink bandwidth allocation rate determining means, the other wireless communication A second downlink band state determination unit for determining a downlink band state in the route;
Based on the determination result of the second downlink band state determination means, the communication control apparatus transmits second downlink transmission control information for controlling a transmission band of a packet transmitted to the other wireless communication path to the communication control apparatus. Second downlink transmission control means for transmitting;
It is characterized by having.

The invention according to claim 5 is the wireless communication apparatus according to claim 4,
The first downlink monitoring period is a transmission period of a predetermined number of sequential packets transmitted by the communication control apparatus to the one wireless communication path at a bandwidth allocation rate determined by the first downlink bandwidth allocation rate determining unit. Corresponding to
The second downlink monitoring period is a transmission period of a predetermined number of packets transmitted by the communication control apparatus to the other wireless communication path at a bandwidth allocation rate determined by the second downlink bandwidth allocation rate determining unit. Corresponding to
It is characterized by this.

The invention according to claim 6 is the wireless communication device according to claim 4 or 5,
The first downlink band state determination means calculates a displacement degree of a reception timing of a packet received via the one wireless communication path within the first downlink monitoring period, and calculates the calculated displacement degree. Based on the comparison with the threshold corresponding to the bandwidth allocation rate determined by the first downlink bandwidth allocation rate determining means, determining the downstream bandwidth state in the one wireless communication path,
The second downlink band state determination unit calculates a degree of displacement of a reception timing of a packet received via the other wireless communication path within the second downlink direction monitoring period, and calculates the degree of displacement calculated. And determining a downstream bandwidth state in the other wireless communication path based on a comparison between the second downstream bandwidth allocation ratio determining unit and a threshold value corresponding to the bandwidth allocation ratio determined by the second downlink bandwidth allocation ratio determining unit.
It is characterized by this.

Furthermore, in the invention according to claim 7 which achieves the above object, a plurality of different wireless communication paths can be used with a wireless communication apparatus, and a single wireless is provided for a required bandwidth of an application having real-time characteristics. A communication control method for controlling communication between the wireless communication apparatus and a communication destination by supplementing a bandwidth that is insufficient in a communication path with another wireless communication path,
Determining a bandwidth allocation ratio of packets transmitted by the wireless communication device to the one wireless communication path;
Based on a packet received via the one wireless communication path within a first uplink monitoring period corresponding to the determined bandwidth allocation rate, an upstream band state in the one wireless communication path is determined. Steps,
Transmitting, based on the determination result, first uplink transmission control information for controlling a transmission band of a packet transmitted by the wireless communication apparatus to the one wireless communication path to the wireless communication apparatus;
Determining a bandwidth allocation ratio of packets transmitted by the wireless communication device to the other wireless communication path;
Based on a packet received via the other wireless communication path within a second uplink monitoring period corresponding to the determined bandwidth allocation ratio, an upstream bandwidth state in the other wireless communication path is determined. Steps,
Transmitting, based on the determination result, second uplink transmission control information for controlling a transmission band of a packet transmitted by the wireless communication apparatus to the other wireless communication path to the wireless communication apparatus;
It is characterized by having.

Furthermore, in the invention according to claim 8 which achieves the above object, a plurality of different wireless communication paths can be used with the communication control apparatus, and one wireless is provided for a requested bandwidth of an application having real-time characteristics to be used. A wireless communication method for complementing a bandwidth shortage in a communication path using another wireless communication path and wirelessly communicating with a communication destination via the communication control device,
Determining a bandwidth allocation ratio of packets transmitted by the communication control device to the one wireless communication path;
Based on a packet received via the one wireless communication path within a first downlink monitoring period corresponding to the determined bandwidth allocation ratio, a downstream band state in the one wireless communication path is determined. Steps,
Based on the determination result, transmitting to the communication control device first downlink transmission control information for controlling a transmission band of a packet transmitted by the communication control device to the one wireless communication path;
Determining a bandwidth allocation ratio of packets transmitted by the communication control device to the other wireless communication path;
Based on a packet received via the other wireless communication path within a second downlink monitoring period corresponding to the determined bandwidth allocation ratio, a downstream bandwidth state in the other wireless communication path is determined. Steps,
Transmitting, based on the determination result, second downlink transmission control information for controlling a transmission band of a packet transmitted by the communication control device to the other wireless communication path to the communication control device;
It is characterized by having.

  According to the present invention, when a plurality of different wireless communication paths are used at the same time and a communication is performed by supplementing a band that is insufficient in one wireless communication path with another wireless communication path, the transmission in each wireless communication path is performed. A communication control device capable of effectively reducing the number of packets discarded without being reproduced due to a delay in arrival time, because the narrowing of the bandwidth can be detected quickly and accurately and notified to the transmission side, A wireless communication device, a communication control method, and a wireless communication method can be provided.

  Next, an embodiment of the present invention will be described with reference to the drawings.

(Overall schematic configuration of communication system)
FIG. 1 is an overall schematic configuration diagram of a communication system 1 according to the present embodiment. As shown in FIG. 1, the communication system 1 includes a wireless IP network 10A and a wireless IP network 10B. The wireless IP network 10A (first wireless IP network) is an IP network capable of transmitting IP packets. In the wireless IP network 10A, a care-of IP address A1 (first care-of IP address) is dynamically assigned to the MN 300 according to the position of the wireless communication device 300 (hereinafter abbreviated as MN 300). In the present embodiment, the wireless IP network 10A is a mobile phone network that uses CDMA (specifically, HRPD, which is a 3GPP2 standard) as a wireless communication method.

  The wireless IP network 10B (second wireless IP network) can transmit IP packets in the same manner as the wireless IP network 10A. In the wireless IP network 10B, a care-of IP address A2 (second care-of IP address) is assigned to the MN 300. In the present embodiment, the wireless IP network 10B uses mobile WiMAX compliant with the IEEE 802.16e standard as a wireless communication method.

  The care-of IP address A1 is given from the wireless IP network 10A when the MN 300 is connected to the wireless IP network 10A. Similarly, the care-of IP address A2 is given from the wireless IP network 10B when the MN 300 is connected to the wireless IP network 10B.

  In the present embodiment, the care-of IP address A1 and the care-of IP address A2 are associated with the home IP address AH (virtual address).

  The switching server 100 and the MN 300 can execute communication using the wireless IP network 10A and the wireless IP network 10B simultaneously. Specifically, the switching server 100 and the MN 300 perform transmission / reception of IP packets by using the wireless IP network 10A as a master route, and when the bandwidth (transfer rate) of the master route is insufficient, Using as a path, the insufficient band is complemented by a slave path.

  The wireless IP network 10A and the wireless IP network 10B are connected to the Internet 20. A relay center 30 is connected to the Internet 20.

  In the relay center 30, a network device that relays IP packets transmitted and received by the MN 300 is installed. Specifically, the switching server 100 and the VPN routers 200A and 200B are installed in the relay center 30.

  The switching server 100 controls a wireless communication path with the MN 300. In the present embodiment, the switching server 100 constitutes a communication control device. Specifically, the switching server 100 can transmit an IP packet to the MN 300 via the wireless IP network 10A, and can transmit an IP packet to the MN 300 via the wireless IP network 10B.

  The VPN routers 200A and 200B execute IP packet routing processing. The VPN routers 200 </ b> A and 200 </ b> B establish a VPN (IPSec) tunnel between the MN 300 and the switching server 100. By establishing the tunnel, OSI layer 3 virtualization is realized, and IP mobility of the MN 300 is ensured.

  That is, in this embodiment, unlike mobile IP (for example, RFC2002), the MN 300 has a master route set via the wireless IP network 10A and a slave route set via the wireless IP network 10B. It is possible to execute communication with a communication destination (specifically, the IP telephone terminal 42) while simultaneously using both wireless communication paths.

  The relay center 30 (switching server 100) is connected to the user premises 40 via a predetermined communication network (not shown). An IP telephone exchange 41 and an IP telephone terminal 42 are installed in the user premises 40. The IP telephone exchange 41 relays IP packets (specifically, VoIP packets) between the predetermined communication network and the IP telephone terminal 42. The IP telephone terminal 42 mutually converts voice signals and VoIP packets, and transmits / receives IP packets.

  That is, in this embodiment, the MN 300 (wireless communication device) executes communication with the IP telephone terminal 42 (communication destination) via the switching server 100 (communication control device).

  Next, the functional block configuration of the communication system 1 will be described. Specifically, functional block configurations of the switching server 100 and the MN 300 included in the communication system 1 will be described. Hereinafter, portions related to the present invention will be mainly described. Therefore, it should be noted that the switching server 100 and the MN 300 may include logic blocks (such as a power supply unit) that are not illustrated or omitted in description, which are essential for realizing the functions of the device.

(Functional block configuration of the switching server 100)
FIG. 2 is a functional block configuration diagram of the switching server 100. As illustrated in FIG. 2, the switching server 100 includes a communication interface unit 101, a communication interface unit 103, a packet relay unit 105, a bandwidth calculation unit 107, a transmission packet distribution processing unit 109, a main control unit 111, and a storage unit 113. .

  The communication interface unit 101 is connected to the VPN router 200A and the VPN router 200B. The communication interface unit 101 can be configured by, for example, 1000BASE-T defined by IEEE 802.3ab.

  Further, as described above, since the VPN by IPSec is set in the present embodiment, the IP packet transmitted / received by the communication interface unit 101, specifically, the VoIP packet transmitted / received between the switching server 100 and the MN300. (Specifically, the VoIP packet transmitted by the MN 300) has the configuration shown in FIG. As shown in FIG. 3A, the home IP header (home IP address AH), TCP / UDP header, and payload are encapsulated and a care-of IP address (care-of IP address A1 or care-of IP address A2) is added. .

  The access control packet transmitted / received between the switching server 100 and the MN 300 has the configuration shown in FIG. The access control packet includes a data link layer header, a care-of IP address, a TCP header, and a control code.

  The communication interface unit 103 is used to execute communication with the IP telephone exchange 41 and the IP telephone terminal 42.

  The packet relay unit 105 relays IP packets transmitted and received by the communication interface unit 101 and the communication interface unit 103. Specifically, the packet relay unit 105 relays the IP packet in accordance with an instruction from the transmission packet distribution processing unit 109 or the main control unit 111. In addition, the packet relay unit 105 includes a jitter buffer that absorbs jitter of IP packets received by the communication interface unit 101 and the communication interface unit 103.

  In the present embodiment, the packet relay unit 105 receives an IP packet (VoIP packet) transmitted from the MN 300 to the IP telephone terminal 42 at a predetermined cycle (20 ms) and relays it to the IP telephone terminal 42. At the same time, the IP telephone terminal 42 receives an IP packet (VoIP packet) transmitted to the MN 300 at a predetermined cycle (20 ms) and configures a relay unit that relays the packet to the MN 300.

  The bandwidth calculating unit 107 calculates the bandwidth (transfer rate) of the wireless IP network 10A and the wireless IP network 10B necessary for receiving an IP packet from the MN 300, and includes a first uplink bandwidth allocation rate determining unit 107A, A first uplink band state determination unit 107B, a second uplink band allocation rate determination unit 107C, and a second uplink band state determination unit 107D are provided.

  The first uplink bandwidth allocation rate determination unit 107A determines the bandwidth allocation rate of the IP packet that the MN 300 transmits to the wireless IP network 10A, and the first uplink bandwidth status determination unit 107B determines the first uplink bandwidth allocation rate determination. Based on the reception timing of sequential IP packets received via the wireless IP network 10A within the first uplink monitoring period based on the bandwidth allocation rate determined by the unit 107A, the upstream bandwidth in the wireless IP network 10A Determine the state.

  Here, the first uplink bandwidth allocation ratio determination unit 107A actually receives the transmission bandwidth control message (first downlink transmission control information) of the wireless IP network 10A received from the MN 300 or the wireless IP network 10A, for example. The bandwidth allocation rate of the wireless IP network 10A is determined based on the received IP packet reception rate or the transmission bandwidth control message (first uplink transmission control information) of the wireless IP network 10A transmitted to the MN 300.

  In addition, the first uplink band state determination unit 107B receives, for example, via the wireless IP network 10A within the first uplink monitoring period based on the band allocation rate determined by the first uplink band allocation rate determination unit 107A. The degree of displacement of the IP packet reception timing is calculated, the calculated degree of displacement is compared with the threshold corresponding to the bandwidth allocation rate determined by the first upstream bandwidth allocation rate determination unit 107A, and the degree of displacement is calculated. If the condition exceeds the threshold value, the bandwidth state is good, and if the displacement degree is less than the threshold value, the current transmission bandwidth (bandwidth allocation rate) in the upstream direction of the IP packet transmitted by the MN 300 to the wireless IP network 10A is regarded as defective. Judge the quality of the.

  Similarly, the second uplink bandwidth allocation rate determination unit 107C determines the bandwidth allocation rate of the IP packet that the MN 300 transmits to the wireless IP network 10B, and the second uplink bandwidth status determination unit 107D Based on the reception timing of sequential IP packets received via the wireless IP network 10B within the second uplink monitoring period based on the bandwidth allocation rate determined by the allocation rate determination unit 107C, the uplink in the wireless IP network 10B Determine the direction bandwidth state.

  Here, in the second uplink bandwidth allocation rate determination unit 107C, for example, as in the first uplink bandwidth allocation rate determination unit 107A, for example, the transmission bandwidth control message (second downlink transmission) of the wireless IP network 10B received from the MN 300 Control information), or the reception rate of IP packets actually received via the wireless IP network 10B, or the transmission bandwidth control message (second uplink transmission control information) of the wireless IP network 10B transmitted to the MN 300 Then, the bandwidth allocation rate of the wireless IP network 10B is determined.

  Further, in the second uplink direction band state determination unit 107D, similarly to the first uplink direction band state determination unit 107B, the second uplink direction monitoring based on the band allocation rate determined by the second uplink direction band allocation rate determination unit 107C. Within the period, for example, the degree of displacement of the reception timing of the IP packet received via the wireless IP network 10B is calculated, and the calculated degree of displacement and the band determined by the second uplink bandwidth allocation rate determination unit 107C An IP packet that the MN 300 transmits to the wireless IP network 10B as a band state is good if the degree of displacement exceeds the threshold value and compared with a threshold value corresponding to the distribution rate, and bad if the degree of displacement is less than the threshold value. The quality of the current transmission band (bandwidth allocation ratio) in the upstream direction is determined.

  A method for determining the upstream bandwidth state in the wireless IP network 10A and the wireless IP network 10B will be described later.

  The transmission packet distribution processing unit 109 executes processing for distributing the IP packet transmitted from the communication interface unit 101 via the packet relay unit 105 to the wireless IP network 10A and the wireless IP network 10B.

  Specifically, the transmission packet distribution processing unit 109 receives the IP phone terminal 42 from the transmission band control message (first downlink transmission control information) of the wireless IP network 10A received by the main control unit 111 from the MN 300. The care-of IP address A1 is added to the received IP packet including the home IP address AH, and the IP packet with the care-of IP address A1 added is transmitted from the communication interface unit 101 to the wireless IP network 10A.

  The transmission packet distribution processing unit 109 also receives the home received from the IP telephone terminal 42 based on the transmission bandwidth control message (second downlink transmission control information) of the wireless IP network 10B received by the main control unit 111 from the MN 300. The care-of IP address A2 is added to the IP packet including the IP address AH, and the IP packet with the care-of IP address A2 added is transmitted from the communication interface unit 101 to the wireless IP network 10B.

  The main control unit 111 controls the wireless communication path of the IP packet transmitted to the MN 300 and the IP packet received from the MN 300. The main control unit 111 executes access control packet processing.

  In particular, in the present embodiment, the main control unit 111 determines that the MN 300 performs wireless IP based on the determination result of the upstream bandwidth state in the wireless IP network 10A by the first upstream bandwidth state determination unit 107B of the bandwidth calculation unit 107. A transmission band control message (first uplink transmission control information) for controlling the transmission band of the VoIP packet transmitted to the network 10A is generated, and the transmission band control message is transmitted via the wireless IP network 10A or the wireless IP network 10B. Send to MN300. Specifically, when the first uplink bandwidth state determination unit 107B determines that the current transmission bandwidth is bad, the bandwidth allocation rate of the VoIP packet transmitted from the MN 300 to the wireless IP network 10A is reduced (transmission rate). If the current transmission band is determined to be good, a transmission band control message for maintaining the transmission band is generated and transmitted to the MN 300. The transmission band control message is transmitted / received using an access control packet (see FIG. 3B).

  Similarly, the main control unit 111 transmits the MN 300 to the wireless IP network 10B based on the determination result of the upstream bandwidth state in the wireless IP network 10B by the second upstream bandwidth state determination unit 107D of the bandwidth computing unit 107. A transmission band control message (second uplink transmission control information) for controlling the transmission band of the VoIP packet is generated, and the transmission band control message is transmitted to the MN 300 via the wireless IP network 10B or the wireless IP network 10A. Specifically, when the second uplink bandwidth state determination unit 107D determines that the current transmission band is bad, the bandwidth allocation rate of the VoIP packet transmitted from the MN 300 to the wireless IP network 10B is reduced (transmission rate). If the current transmission band is determined to be good, a transmission band control message for maintaining the transmission band is generated and transmitted to the MN 300.

  The main control unit 111 calculates a transmission band of a VoIP packet to be transmitted to the wireless IP network 10A based on a transmission band control message (first downlink transmission control information) for the wireless IP network 10A received from the MN 300. And a function for calculating a transmission band of a VoIP packet to be transmitted to the wireless IP network 10B based on a transmission band control message (second downlink transmission control information) for the wireless IP network 10B received from the MN 300. Have. In the present embodiment, the main control unit 111 constitutes first uplink transmission control means and second uplink transmission control means.

  The main control unit 111 also checks the order of IP packets received via the wireless IP network 10A and the wireless IP network 10B. In the present embodiment, the main control unit 111 checks a sequence number (SN) of RTP (real-time transport protocol) included in a VoIP packet transmitted / received between the MN 300 and the IP telephone terminal 42. Further, the main control unit 111 acquires statistical information (for example, packet loss, throughput, jitter buffer underrun count and overrun count) of the IP packet relayed by the packet relay unit 105, and transmits the acquired information to the MN 300. can do.

  The storage unit 113 stores an application program that provides the function of the switching server 100. In addition, the storage unit 113 stores information regarding networks such as the wireless IP network 10A and the wireless IP network 10B.

  In particular, in the present embodiment, the home IP address AH of the MN 300 associated with the care-of IP address A1 and the care-of IP address A2 is stored. Specifically, the main control unit 111 causes the storage unit 113 to store the care-of IP address A1, the care-of IP address A2, and the home IP address AH notified from the MN 300. In the present embodiment, the main control unit 111 and the storage unit 113 constitute a virtual address acquisition unit.

  The main control unit 111 sets the home IP address AH included in the IP packet transmitted by the IP telephone terminal 42 and the home IP address registered in a home agent (not shown) accessible via the Internet 20. Verification can be performed. When the main control unit 111 performs the collation, it can be determined which home IP address AH is the home IP address assigned to the MN 300 by any communication carrier.

(Function block configuration of MN300)
FIG. 4 is a functional block configuration diagram of the MN 300. Similar to the switching server 100, the MN 300 can execute communication using the wireless IP network 10A and the wireless IP network 10B simultaneously. Hereinafter, description of functional blocks similar to those of the switching server 100 described above will be omitted as appropriate.

  As shown in FIG. 4, the MN 300 includes a wireless communication card 301, a wireless communication card 303, a care-of IP address interface unit 305A, a care-of IP address interface unit 305B, a bandwidth calculation unit 307, a transmission packet distribution processing unit 309, and a main control unit. 311 and a storage unit 313.

  The wireless communication card 301 executes wireless communication of a wireless communication method (HRPD, which is a 3GPP2 standard) used in the wireless IP network 10A. In the present embodiment, the wireless communication card 301 transmits and receives IP packets (VoIP packets) to and from the IP telephone terminal 42 at a predetermined cycle (for example, 20 ms) via the wireless IP network 10A.

  The wireless communication card 303 executes wireless communication conforming to a wireless communication method (mobile WiMAX) used in the wireless IP network 10B.

  The care-of IP address interface unit 305 </ b> A is connected to the wireless communication card 301. The care-of IP address interface unit 305A transmits and receives IP packets based on the care-of IP address A1 assigned to the MN 300 in the wireless IP network 10A.

  The care-of IP address interface unit 305B is connected to the wireless communication card 303. The care-of IP address interface unit 305B transmits and receives IP packets based on the care-of IP address A2 assigned to the MN 300 in the wireless IP network 10B.

  The bandwidth calculation unit 307 calculates the bandwidth (transfer rate) of the wireless IP network 10A and the wireless IP network 10B necessary for receiving an IP packet from the switching server 100, and is a first downlink bandwidth allocation rate determination unit. 307A, a first downlink band state determination unit 307B, a second downlink band distribution rate determination unit 307C, and a second downlink band state determination unit 307D. The specific function of the band calculation unit 307 is substantially the same as that of the band calculation unit 107 described above.

  That is, the first downlink bandwidth allocation rate determination unit 307A determines the bandwidth allocation rate of the IP packet transmitted from the switching server 100 to the wireless IP network 10A, and the first downlink bandwidth status determination unit 307B determines the first downlink bandwidth allocation rate determination unit 307B. Based on the reception timing of sequential IP packets received via the wireless IP network 10A within the first downlink monitoring period based on the bandwidth allocation ratio determined by the bandwidth allocation ratio determination unit 307A, the wireless IP network 10A Determine the downstream bandwidth state.

  Here, in the first downlink bandwidth allocation ratio determination unit 307A, for example, the transmission bandwidth control message (first uplink transmission control information) of the wireless IP network 10A received from the switching server 100 or the wireless IP network 10A is actually transmitted. The bandwidth allocation rate of the wireless IP network 10A is determined based on the reception rate of the received IP packet or the transmission bandwidth control message (first downlink transmission control information) of the wireless IP network 10A transmitted to the switching server 100. judge.

  Further, the first downlink band state determination unit 307B receives, for example, via the wireless IP network 10A within the first downlink monitoring period based on the band allocation rate determined by the first downlink band allocation rate determination unit 307A. The degree of displacement of the IP packet reception timing is calculated, the calculated degree of displacement is compared with the threshold corresponding to the bandwidth allocation rate determined by the first downlink bandwidth allocation rate determination unit 307A, If the condition exceeds the threshold value, the bandwidth state is good, and if the displacement degree is less than the threshold value, the current state is the current transmission bandwidth (bandwidth distribution) in the downlink direction of the IP packet that the switching server 100 transmits to the wireless IP network 10A. Rate) is judged.

  Similarly, the second downlink bandwidth allocation rate determination unit 307C determines the bandwidth allocation rate of the IP packet that the switching server 100 transmits to the wireless IP network 10B, and the second downlink bandwidth status determination unit 307D Based on the reception timing of sequential IP packets received via the wireless IP network 10B within the second downlink monitoring period based on the bandwidth allocation ratio determined by the direction bandwidth allocation ratio determination unit 307C, the wireless IP network 10B The bandwidth state in the downstream direction at is determined.

  Here, in the second downlink bandwidth allocation ratio determination unit 307C, for example, as in the first downlink bandwidth allocation ratio determination unit 307A, for example, the transmission bandwidth control message (second uplink bandwidth management message of the wireless IP network 10B received from the switching server 100) Direction transmission control information), the reception rate of IP packets actually received via the wireless IP network 10B, or the transmission bandwidth control message (second downlink transmission control information) of the wireless IP network 10B transmitted to the switching server 100 ) To determine the bandwidth allocation rate of the wireless IP network 10B.

  Further, in the second downlink band state determination unit 307D, similarly to the first downlink band state determination unit 307B, the second downlink monitoring based on the band allocation rate determined by the second downlink band allocation rate determination unit 307C Within the period, for example, the degree of displacement of the reception timing of the IP packet received via the wireless IP network 10B is calculated, and the calculated degree of displacement and the band determined by the second downlink band allocation rate determination unit 307C When the degree of displacement exceeds the threshold, the bandwidth state is good, and when the degree of displacement is equal to or less than the threshold, the switching server 100 transmits to the wireless IP network 10B as bad. The quality of the current transmission bandwidth (bandwidth allocation rate) in the downlink direction of the IP packet is determined.

  A method of determining the downstream bandwidth state in the wireless IP network 10A and the wireless IP network 10B will be described later.

  Based on the transmission band control message (first uplink transmission control information) received by the main control unit 311 from the switching server 100, the transmission packet distribution processing unit 309 includes an IP including a home IP address AH and a care-of IP address A1. Generate a packet. The generated IP packet is transmitted from the main control unit 311 to the wireless IP network 10A via the care-of IP address interface unit 305A and the wireless communication card 301.

  Further, the transmission packet distribution processing unit 309 determines the home IP address AH and the care-of IP address A2 based on the transmission bandwidth control message (second uplink transmission control information) received by the main control unit 311 from the switching server 100. An included IP packet is generated. The generated IP packet is transmitted from the main control unit 311 to the wireless IP network 10B via the care-of IP address interface unit 305B and the wireless communication card 303.

  The main control unit 311 controls the wireless communication path of the IP packet transmitted to the switching server 100 and the IP packet received from the switching server 100, similarly to the main control unit 111 (see FIG. 2) of the switching server 100. In addition, the main control unit 311 executes access control packet processing.

  In the present embodiment, the main control unit 311 determines that the switching server 100 has the wireless IP based on the determination result of the downstream bandwidth state in the wireless IP network 10A by the first downstream bandwidth state determination unit 307B of the bandwidth calculation unit 307. A transmission band control message (first downlink transmission control information) for controlling the transmission band of the VoIP packet transmitted to the network 10A is generated, and the transmission band control message is transmitted via the wireless IP network 10A or the wireless IP network 10B. It transmits to the switching server 100. Specifically, when the first downlink bandwidth state determination unit 307B determines that the current transmission band is bad, the bandwidth allocation rate of the VoIP packet that the switching server 100 transmits to the wireless IP network 10A is lowered. When the current transmission band is determined to be good, a transmission band control message for maintaining the transmission band is generated and transmitted to the switching server 100.

  Similarly, the main control unit 311 transmits from the switching server to the wireless IP network 10B based on the determination result of the downstream bandwidth state in the wireless IP network 10B by the second downstream bandwidth state determination unit 307D of the bandwidth computing unit 307. A transmission bandwidth control message (second downlink transmission control information) for controlling the transmission bandwidth of the VoIP packet to be generated is generated, and the transmission bandwidth control message is transmitted to the switching server 100 via the wireless IP network 10B or the wireless IP network 10A. Send. Specifically, when the second downlink band state determination unit 307D determines that the current transmission band is bad, the bandwidth allocation rate of the VoIP packet that the switching server 100 transmits to the wireless IP network 10B is lowered. When the current transmission band is determined to be good, a transmission band control message for maintaining the transmission band is generated and transmitted to the switching server 100.

  The main control unit 311 calculates the transmission band of the VoIP packet to be transmitted to the wireless IP network 10B based on the transmission band control message (first uplink transmission control information) for the wireless IP network 10A received from the switching server 100. And the transmission bandwidth of the VoIP packet to be transmitted to the wireless IP network 10A based on the transmission bandwidth control message (second uplink transmission control information) for the wireless IP network 10B received from the switching server 100. It also has a function to calculate. In the present embodiment, the main controller 311 constitutes a first downlink transmission control means and a second downlink transmission control means.

  The main control unit 311 also has a sequence number (SN) of an RTP (real-time transport protocol) included in a VoIP packet transmitted / received to / from the IP telephone terminal 42, like the main control unit 111 of the switching server 100. Check. Further, the main control unit 311 acquires information (for example, throughput, SINR, RSSI, DRC, and transmission power) indicating the quality of wireless communication executed in the wireless communication card 301 and the wireless communication card 303, and acquires the acquired information. Based on this, it is also possible to predict the bandwidth (downward and upstream) of the wireless IP network 10A and the wireless IP network 10B necessary for communication.

  The storage unit 313 stores application programs that provide the functions of the MN 300. Further, the storage unit 313 stores the home IP address AH of the MN 300 associated with the care-of IP address A1 and the care-of IP address A2. In the present embodiment, the storage unit 313 constitutes a virtual address storage unit.

(Band status judgment method)
Next, a method for determining the upstream and downstream bandwidth states in each of the wireless IP network 10A and the wireless IP network 10B described above will be described.

  In the present embodiment, each of the switching server 100 and the MN 300 determines the bandwidth allocation rate in each wireless communication path, and receives it via the corresponding wireless communication path within a monitoring period that is inversely proportional to the determined bandwidth allocation ratio. Based on the reception timing of the received sequential packets, determines the band state in the wireless communication path, generates a transmission band control message for controlling the transmission band based on the determination result, and transmits the transmission band control message Is transmitted to the packet destination, thereby controlling the transmission band of the packet in the wireless communication path.

  5 to 7 illustrate transmission band determination results according to the present embodiment when VoIP packets transmitted at 20 ms intervals are received, as in FIG. 9, and FIG. FIG. 6 illustrates the case where the bandwidth allocation ratio is 50%, and FIG. 7 illustrates the case where the bandwidth allocation ratio is 100%. 5 to 7, the horizontal axis indicates time t, and the vertical axis indicates a packet sequence number (SN). Tm indicates a monitoring period based on the bandwidth allocation rate of the wireless communication path. The other symbols are the same as in FIG. 9, Dp indicates a potential delay time (in this case, 80 ms) from the transmission timing of the VoIP packet to the ideal reception timing in the route, and Tb is from the transmission timing of the VoIP packet. The reproduction allowable time (here, 200 ms) is indicated, and Ds indicates the stay delay time.

  In the present embodiment, the monitoring period Tm that is inversely proportional to the bandwidth allocation ratio is set as a transmission packet period of 5 packets according to the bandwidth allocation ratio, for example, and the reception timing of the IP packet received within this monitoring period Tm is set. The degree of displacement α is calculated according to the following equation (1), and α ≦ αth based on a comparison between the calculated degree of displacement α and a threshold value αth corresponding to the bandwidth allocation rate determined for the communication path. In this case, it is determined that the communication path is narrowed. In equation (1), s represents a reception number assigned to a packet received within the monitoring period Tm, mean represents an averaging process, SN represents an IP packet sequence number, and Trec represents a reception time.

  In this way, Tm = 400 ms at the bandwidth allocation rate of 25% in FIG. 5, Tm = 200 ms at the bandwidth allocation rate of 50% in FIG. 6, and Tm = 100 ms at the bandwidth allocation rate of 100% in FIG. . That is, the higher the bandwidth allocation rate (the higher the transmission rate), the shorter Tm. Therefore, when the allowable bandwidth of a communication path with a high bandwidth allocation ratio is narrowed, it is possible to quickly detect the narrowing of the bandwidth and effectively reduce the number of packets remaining in the communication path. It is possible to accurately detect the narrowing of the allowable bandwidth in the communication path with a low bandwidth allocation ratio and effectively reduce the number of packets staying in the communication path.

  For example, in FIGS. 5 to 7, it is assumed that the allowable bandwidth of the wireless communication path is narrowed to 50% from the time t1 when the packet SN1 is received. In this case, when the bandwidth allocation rate is 25% in FIG. 5, the wireless communication path is narrowed in the monitoring period Tm (t2-t3) at time t3 when the next packet SN3 (indicated by a black circle) is received. Is determined, the stay delay time Ds generated in the packet transmitted up to time t3 is 240 ms. Therefore, in this case, the number of discarded packets exceeding the reproduction allowable line (circled in the figure) is only 2 packets.

  In the case of the bandwidth allocation ratio of 50% in FIG. 6, the monitoring period Tm (t2-t3) at the time t3 when the second packet SN3 (shown by a black circle) is received after the packet SN1 is received at the time t1. ), It is determined that the wireless communication path has narrowed the band, the residence delay time Ds generated in the packet transmitted up to time t3 is 240 ms. Accordingly, in this case, the number of discarded packets exceeding the reproduction allowable line (circled in the figure) is only 3 packets.

  Similarly, in the case of the bandwidth allocation rate of 100% in FIG. 7, the monitoring period Tm (t2−2) at time t3 when the second packet SN3 (shown by a black circle) is received after receiving the packet SN1 at time t1. If it is determined at t3) that the wireless communication path is narrowed, the stay delay time Ds generated in the packet transmitted up to time t3 is 160 ms. Therefore, in this case, the number of discarded packets exceeding the reproduction allowable line (circled in the figure) is only 2 packets.

  The monitoring period Tm shown in FIGS. 5 to 7 corresponds to the first uplink monitoring period of the wireless IP network 10A or the second uplink monitoring period of the wireless IP network 10B in the switching server 100, and is wireless in the MN 300. This corresponds to the first downlink monitoring period of the IP network 10A or the second downlink monitoring period of the wireless IP network 10B.

  Thus, the monitoring period Tm that is inversely proportional to the bandwidth allocation ratio is set for each of the uplink direction and the downlink direction of the wireless IP network 10A and the wireless IP network 10B, and the reception timing of the IP packet received within the monitoring period Tm is set. If the degree of displacement α is calculated, and it is determined that the allowable bandwidth of the communication path is narrowed when the calculated degree of displacement α is equal to or less than the threshold value αth corresponding to the bandwidth allocation rate of the communication path. In the switching server 100, the wireless IP network 10A and the wireless are detected by detecting the fluctuation of the allowable band due to the change of the propagation environment such as fading quickly and accurately. Transmission bandwidth control message for controlling the transmission bandwidth of IP network 10B It can be transmitted. Therefore, if the transmission bandwidth in the wireless communication path is controlled based on the transmission bandwidth control message, the number of discarded packets is effective in real-time applications such as VoIP without being reproduced due to arrival time delay due to fluctuations in the allowable bandwidth. Can be reduced.

(Operation of communication system)
Next, the operation of the above-described communication system will be described with reference to FIG. FIG. 8 is a communication sequence diagram executed between the switching server 100 and the MN 300. As shown in FIG. 8, in step S10, the switching server 100 and the MN 300 transmit and receive VoIP packets via the wireless IP network 10A (master route) and the Internet 20. The VoIP packet is transmitted / received along with a voice call between the MN 300 and the IP telephone terminal 42 (see FIG. 1).

  Specifically, the MN 300 encapsulates the payload including the IP address assigned to the IP telephone terminal 42 and the home IP address AH, and uses the care-of IP address A1 as the transmission source address (FIG. 3A). Send).

  The switching server 100 encapsulates the VoIP packet transmitted from the IP telephone terminal 42 and transmits an IP packet having the care-of IP address A1 as a destination address.

  In the figure, a “black square” is marked on the network through which the VoIP packet passes (hereinafter the same). In step S10, all VoIP packets pass through the wireless IP network 10A (master route) and the Internet 20.

  Therefore, in this state, in the switching server 100, the first upstream bandwidth allocation rate determination unit 107A of the bandwidth computing unit 107 determines that the upstream bandwidth allocation rate of the wireless IP network 10A is 100%. In the first downlink bandwidth allocation rate determination unit 307A of the calculation unit 307, the downlink bandwidth allocation rate of the wireless IP network 10A is determined to be 100%.

  Thereafter, in step S20A, the MN 300 sets the bandwidth allocation rate determined by the first downlink bandwidth allocation rate determination unit 307A (100% in this case) in the first downlink bandwidth status determination unit 307B of the bandwidth calculation unit 307. Based on the VoIP packet actually received via the wireless IP network 10A within the inversely proportional first downlink monitoring period Tm (for example, Tm = 100 ms), the degree of displacement of the reception timing of the VoIP packet from the above equation (1). α is calculated, and the degree of displacement α is compared with a threshold value αth corresponding to the bandwidth allocation rate determined by the first downlink bandwidth allocation rate determination unit 307A, and the current downlink direction in the wireless IP network 10A is compared. The quality of the transmission band is determined.

  Similarly, in step S20B, the switching server 100 uses the bandwidth allocation rate determined by the first uplink bandwidth allocation rate determination unit 107A in the first uplink bandwidth status determination unit 107B of the bandwidth calculation unit 107 (in this case, 100 %) In the first uplink monitoring period Tm (eg, Tm = 100 ms), based on the VoIP packet actually received through the wireless IP network 10A, the reception timing of the VoIP packet is calculated from the above equation (1). The degree of displacement α is calculated, and the degree of displacement α is compared with the threshold value αth corresponding to the bandwidth allocation rate determined by the first upstream bandwidth allocation rate determination unit 107A, and the current level in the wireless IP network 10A is compared. The quality of the upstream transmission band is determined.

  In step S30A, when the first uplink bandwidth state determination unit 107B determines that the current transmission bandwidth is bad, the switching server 100 determines the bandwidth allocation rate of the VoIP packet that the MN 300 transmits to the wireless IP network 10A. A transmission band control message (first uplink transmission control information) for controlling the transmission band so as to be lowered is generated and transmitted to the MN 300.

  In step S30B, when the first downlink bandwidth state determination unit 307B determines that the current transmission bandwidth is bad, the MN 300 sets the bandwidth allocation rate of the VoIP packet that the switching server 100 transmits to the wireless IP network 10A. A transmission band control message (first downlink transmission control information) for controlling the transmission band so as to be lowered is generated and transmitted to the switching server 100.

  In step S40A, the switching server 100 controls the transmission band of the VoIP packet to be transmitted to the wireless IP network 10A based on the transmission band control message (first downlink transmission control information) received from the MN 300, and the VoIP packet Transmit to the wireless IP network 10A.

  In step S40B, the MN 300 controls the transmission band of the VoIP packet to be transmitted to the wireless IP network 10A based on the transmission band control message (first uplink transmission control information) received from the switching server 100, and transmits the VoIP packet. Transmit to the wireless IP network 10A.

  In step S50A, the switching server 100 calculates the transmission band of the VoIP packet to be transmitted to the wireless IP network 10B that is the slave path, based on the transmission band control message (first downlink transmission control information) received from the MN 300, A VoIP packet is transmitted to the wireless IP network 10B according to the calculated transmission band.

  In step S50B, the MN 300 calculates the transmission band of the VoIP packet to be transmitted to the wireless IP network 10B that is the slave path, based on the transmission band control message (first uplink transmission control information) received from the switching server 100, A VoIP packet is transmitted to the wireless IP network 10B according to the calculated transmission band.

  Through these steps S50A and S50B, the VoIP packet passes through the wireless IP network 10B and the Internet 20. That is, the bandwidth that is insufficient in the wireless IP network 10A is supplemented by the wireless IP network 10B.

  Thereafter, with respect to the wireless IP network 10B, in the switching server 100, the second upstream bandwidth allocation rate determination unit 107C of the bandwidth computing unit 107 determines the upstream bandwidth allocation rate of the wireless IP network 10B, and the second upstream bandwidth allocation rate determination unit 107C In the direction band state determination unit 107D, the VoIP actually received via the wireless IP network 10B within the second uplink monitoring period Tm that is inversely proportional to the band allocation rate determined by the second uplink band allocation rate determination unit 107C. Based on the packet, the degree of displacement α of the reception timing of the VoIP packet is calculated from the above equation (1), and the degree of displacement α and the bandwidth allocation rate determined by the second upstream bandwidth allocation rate determination unit 107C are calculated. Compare the corresponding threshold value αth to determine whether the current upstream transmission band in the wireless IP network 10B is good or bad , And transmits to the MN300 to generate a transmission band control message based on the determination result (the second uplink transmission control information).

  Similarly, with respect to the wireless IP network 10B, in the MN 300, the second downlink direction bandwidth allocation rate determination unit 307C of the bandwidth calculation unit 307 determines the downstream bandwidth allocation rate of the wireless IP network 10B, and the second downlink direction. In the bandwidth state determination unit 307D, the VoIP packet actually received via the wireless IP network 10B within the second downstream monitoring period Tm that is inversely proportional to the bandwidth allocation rate determined by the second downlink bandwidth allocation rate determination unit 307C. Based on the above, the degree of displacement α of the reception timing of the VoIP packet is calculated from the above equation (1) and corresponds to the degree of displacement α and the bandwidth allocation rate determined by the second downlink bandwidth allocation rate determination unit 307C. To determine whether the current downstream transmission band in the wireless IP network 10B is good or bad. Generating transmission band control message based on (second downlink transmission control information) to be transmitted to the switching server 100.

  Thereby, the switching server 100 distributes and transmits the VoIP packet received from the IP telephone terminal 42 to the wireless IP network 10B based on the transmission band control message (second downlink transmission control information) received from the MN 300, Based on the transmission band control message (second uplink transmission control information) received from the switching server 100, the MN 300 distributes the VoIP packet to the wireless IP network 10B and transmits it.

  Also for the wireless IP network 10A that is the master route, in the switching server 100, the first upstream bandwidth allocation rate determination unit 107A of the bandwidth computing unit 107 determines the upstream bandwidth allocation rate of the wireless IP network 10A. The first uplink band state determination unit 107C passes through the wireless IP network 10A within the first uplink monitoring period Tm that is inversely proportional to the band allocation rate determined by the first uplink band allocation rate determination unit 107C. Based on the actually received VoIP packet, the displacement degree α of the reception timing of the VoIP packet is calculated from the above equation (1), and the displacement degree α is determined by the first upstream bandwidth allocation rate determination unit 107A. Compared with the threshold value αth corresponding to the bandwidth allocation ratio, the current uplink transmission in the wireless IP network 10A To determine the quality of the band, and transmits to the MN300 to generate a transmission band control message based on the determination result (the first uplink transmission control information).

  Similarly, with respect to the wireless IP network 10A, in the MN 300, the first downlink direction bandwidth allocation rate determination unit 307A of the bandwidth calculation unit 307 determines the downstream bandwidth allocation rate of the wireless IP network 10A, and the first downlink direction. In the bandwidth state determination unit 307B, the VoIP packet actually received via the wireless IP network 10A within the first downstream monitoring period Tm that is inversely proportional to the bandwidth allocation rate determined by the first downlink bandwidth allocation rate determination unit 307A. Based on the above, the degree of displacement α of the reception timing of the VoIP packet is calculated from the above equation (1) and corresponds to the degree of displacement α and the bandwidth allocation rate determined by the first downlink bandwidth allocation rate determination unit 307A. To determine whether the current downstream transmission band in the wireless IP network 10A is good or bad. Generate a based transmission band control message (first downlink transmission control information) to be transmitted to the switching server 100.

  Thereby, the switching server 100 distributes and transmits the VoIP packet received from the IP telephone terminal 42 to the wireless IP network 10A based on the transmission bandwidth control message (first downlink transmission control information) received from the MN 300, Based on the transmission band control message (first uplink transmission control information) received from the switching server 100, the MN 300 distributes the VoIP packet to the wireless IP network 10A and transmits it.

  For example, a plurality of transmission bandwidths (bandwidth allocation ratios) to be controlled are prepared in advance in each of the switching server 100 and the MN 300, and each time a transmission bandwidth control message for reducing the bandwidth allocation ratio is received, the bandwidth allocation is gradually reduced. Select and set the rate.

  As described above, according to the switching server 100 of the present embodiment, the wireless IP network 10A is based on the transmission band control message (first downlink transmission control information and second downlink transmission control information) received from the MN 300. Since the VoIP packet is distributed to the wireless IP network 10B, the VoIP packet can be reliably transmitted to the MN 300 while supplementing the insufficient bandwidth in the wireless IP network 10A using the wireless IP network 10B.

  Similarly, according to the MN 300 of the present embodiment, based on the transmission band control message (first uplink transmission control information and second uplink transmission control information) received from the switching server 100, the radio IP network 10A and the radio Since the VoIP packet is distributed to the IP network 10B, the VoIP packet can be reliably transmitted to the switching server 100 while supplementing the insufficient bandwidth in the wireless IP network 10A using the wireless IP network 10B.

  Moreover, the transmission bandwidth control message sets a monitoring period Tm that is inversely proportional to the bandwidth allocation ratio for each of the uplink direction and the downlink direction of the wireless IP network 10A and the wireless IP network 10B in the switching server 100 and the MN 300. The wireless IP network 10A and the wireless IP network are created based on the comparison between the degree of displacement α of the reception timing of the IP packet received within Tm and the threshold value αth corresponding to the bandwidth allocation ratio of the communication path. Adapting to the communication system of 10B, it is possible to detect the band fluctuation in real time and control the transmission band. Therefore, in a real-time application such as VoIP, it is possible to effectively reduce the number of packets discarded without being reproduced due to a delay in arrival time due to fluctuations in the allowable bandwidth.

  In addition, this invention is not limited to the said embodiment, Many deformation | transformation or a change is possible. For example, the communication system 1 includes the wireless IP network 10A and the wireless IP network 10B. However, more wireless IP networks may be used. In the above-described embodiment, the insufficient transmission band is supplemented in both the upstream direction and the downstream direction. However, the transmission band in the upstream direction or the downstream direction may be supplemented. Further, the wireless communication card 301 or the wireless communication card 303 in the MN 300 may be a wireless unit built in the MN 300.

  Furthermore, in the above embodiment, the average value of the reception timing difference between sequential IP packets is calculated as the displacement degree α, but the displacement degree α in this case has a meaning as it is closer to the current time. The closer to the current time, the larger the weighting factor can be calculated by averaging. Since one or two received packets may deviate greatly from the ideal reception timing, the threshold value αth can be changed according to the number of the received packets. That is, the threshold αth is increased as the number of received packets deviating from the ideal reception timing increases. In this way, erroneous detection can be prevented. In this case, for example, using a received packet determined not to be in a staying state, a statistical amount of a reception time difference between sequential received packets is calculated, and a threshold αth is set based on the lowest slope. Threshold value αth is set based on the minimum value of the reception time difference between sequential received packets, the minimum value of the reception time difference between one skipped received packet, the minimum value of the reception time difference between two skipped received packets, etc. You can also do it.

  Further, when the degree of displacement α is less than the threshold αth, a bandwidth allocation rate is calculated based on the difference, and the calculated bandwidth allocation rate is transmitted to the packet sending side as a transmission bandwidth control message. It is also possible to control the transmission bandwidth by transmitting the difference as a transmission bandwidth control message to the packet sending side and calculating the bandwidth allocation rate based on the difference on the sending side.

  If the degree of displacement α exceeds the threshold αth, a bandwidth allocation rate higher than the current bandwidth allocation rate is calculated based on the difference, and the calculated bandwidth allocation rate is transmitted as a transmission bandwidth control message. Or send the above difference as a transmission bandwidth control message to the sending side of the packet, and calculate a bandwidth allocation rate higher than the current bandwidth allocation rate based on the difference on the sending side, The transmission band can also be controlled.

  Further, in the present invention, since the monitoring period Tm is inversely proportional to the bandwidth allocation ratio, the number of received packets within the monitoring period Tm is monitored without calculating the displacement degree α as in the above-described embodiment, Based on the comparison between the number of received packets and the scheduled number of received packets (threshold value) corresponding to the bandwidth allocation rate of the communication path, the bandwidth state of the communication path can be determined. Also, in this case, the bandwidth allocation ratio is calculated based on the difference between the number of received packets and the threshold value and transmitted as a transmission bandwidth control message to the packet sending side, or the above difference is transmitted as a transmission bandwidth control message. It is also possible to control the transmission bandwidth by transmitting to the transmission side and calculating the bandwidth allocation rate based on the difference on the transmission side.

  In addition, the control of the transmission band by the transmission band control message is not limited to the corresponding wireless path, and other wireless paths are simultaneously executed so as to supplement each other, or when there is another wireless path, the wireless path It is also possible to supplement a narrow band by newly using a route. For example, in the switching server 100, when the bandwidth allocation rate of packets transmitted to the wireless IP network 10B is reduced based on the transmission bandwidth control message (second downlink transmission control information) from the MN 300, the decrease is compensated. Thus, it is possible to control the transmission band so as to increase the bandwidth allocation ratio of packets transmitted to the wireless IP network 10A, or to further compensate for the decrease by another wireless path. .

1 is an overall schematic configuration diagram of a communication system according to an embodiment of the present invention. It is a functional block block diagram of the switching server shown in FIG. It is a block diagram of the IP packet which concerns on embodiment shown in FIG. It is a functional block block diagram of MN shown in FIG. It is a figure which shows the monitoring period Tm in the case of the bandwidth allocation rate 25% by embodiment of this invention. It is a figure which shows the monitoring period Tm in the case of the bandwidth allocation rate 50% by embodiment of this invention. It is a figure which shows the monitoring period Tm in the case of the bandwidth allocation rate 100% by embodiment of this invention. It is a communication sequence diagram performed between the switching server and MN which concern on embodiment of this invention. It is a figure for demonstrating the determination method of the transmission band when a monitoring period is fixed, and the malfunction in that case.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Communication system 10A, 10B Wireless IP network 20 Internet 30 Relay center 40 User premises 41 IP telephone exchange 42 IP telephone terminal
DESCRIPTION OF SYMBOLS 100 Switching server 101,103 Communication interface part 105 Packet relay part 107 Band operation part 107A 1st uplink direction band allocation rate determination part 107B 1st uplink direction band state determination part 107C 2nd uplink direction band allocation rate determination part 107D 2nd uplink Direction band state determination unit 109 Transmission packet distribution processing unit 111 Main control unit 113 Storage unit 200A, 200B VPN router 300 MN (wireless communication apparatus)
301, 303 Wireless communication cards 305A, 305B Care-of IP address interface unit 307 Band operation unit 307A First downlink band allocation rate determination unit 307B First downlink band state determination unit 307C Second downlink band allocation rate determination unit 307D Second Downlink bandwidth state determination unit 309 Transmission packet distribution processing unit 311 Main control unit 313 Storage unit A1, A2 Care-of IP address AH Home IP address

Claims (8)

A plurality of different wireless communication paths can be used with the wireless communication device, and the bandwidth that is lacking in one wireless communication path is used for the required bandwidth of the application having real-time characteristics to be used. A communication control device for controlling communication between the wireless communication device and a communication destination,
First uplink bandwidth allocation ratio determining means for determining a bandwidth allocation ratio of a packet transmitted by the wireless communication apparatus to the one wireless communication path;
The one wireless communication based on a packet received through the one wireless communication path within a first uplink monitoring period according to the bandwidth allocation rate determined by the first uplink bandwidth allocation rate determining means. First upstream bandwidth state determination means for determining upstream bandwidth state in the path;
Based on the determination result of the first uplink band state determination unit, the wireless communication apparatus transmits first uplink transmission control information for controlling a transmission band of a packet transmitted by the wireless communication apparatus to the one wireless communication path. First uplink transmission control means for transmitting;
A second upstream bandwidth allocation ratio determining means for determining a bandwidth allocation ratio of a packet transmitted by the wireless communication apparatus to the other wireless communication path;
Based on the packet received through the other wireless communication path within the second uplink monitoring period according to the bandwidth allocation rate determined by the second uplink bandwidth allocation rate determining means, the other wireless communication A second upstream bandwidth state determination means for determining an upstream bandwidth state in the path;
Based on the determination result of the second uplink band state determination means, the wireless communication apparatus transmits second uplink transmission control information for controlling a transmission band of a packet transmitted by the wireless communication apparatus to the other wireless communication path. Second uplink transmission control means for transmitting;
A communication control device comprising: The first uplink monitoring period is a transmission period of a predetermined number of sequential packets transmitted by the wireless communication apparatus to the one wireless communication path at a bandwidth allocation rate determined by the first uplink bandwidth allocation rate determining unit. Corresponding to
The second uplink monitoring period is a transmission period of a predetermined number of sequential packets transmitted by the wireless communication apparatus to the other wireless communication path at the bandwidth allocation rate determined by the second uplink bandwidth allocation rate determining unit. Corresponding to
The communication control apparatus according to claim 1. The first uplink bandwidth state determination means calculates a displacement degree of a reception timing of a packet received via the one wireless communication path within the first uplink monitoring period, and calculates the calculated displacement degree. Based on the comparison with the threshold corresponding to the bandwidth allocation rate determined by the first uplink bandwidth allocation rate determining means, the upstream bandwidth state in the one wireless communication path is determined,
The second uplink bandwidth state determining means calculates a displacement degree of a reception timing of a packet received through the other wireless communication path within the second uplink monitoring period, and calculates the calculated displacement degree. And determining the upstream bandwidth state in the other wireless communication path based on a comparison between the second upstream bandwidth allocation rate determining means and a threshold corresponding to the bandwidth allocation rate determined by the second uplink bandwidth allocation rate determining means,
The communication control apparatus according to claim 1 or 2, characterized by the above. A plurality of different wireless communication paths can be used with the communication control device, and other wireless communication paths can be used for the bandwidth required by one wireless communication path for the requested bandwidth of the application that has real-time characteristics. And a wireless communication device that wirelessly communicates with a communication destination via the communication control device,
First downlink bandwidth allocation ratio determining means for determining a bandwidth allocation ratio of a packet transmitted by the communication control device to the one wireless communication path;
The one wireless communication based on a packet received via the one wireless communication path within a first downlink monitoring period according to the bandwidth allocation rate determined by the first downlink bandwidth allocation rate determining means. First downstream band state determination means for determining a downstream band state in the path;
Based on the determination result of the first downlink band state determination unit, the communication control apparatus transmits first downlink transmission control information for controlling a transmission band of a packet transmitted to the one wireless communication path to the communication control apparatus. First downlink transmission control means for transmitting;
Second downlink bandwidth allocation ratio determining means for determining a bandwidth allocation ratio of a packet transmitted by the communication control device to the other wireless communication path;
Based on the packet received via the other wireless communication path within the second downlink monitoring period corresponding to the bandwidth allocation rate determined by the second downlink bandwidth allocation rate determining means, the other wireless communication A second downlink band state determining unit for determining a downlink band state in the route;
Based on the determination result of the second downlink band state determination means, the communication control apparatus transmits second downlink transmission control information for controlling a transmission band of a packet transmitted to the other wireless communication path to the communication control apparatus. Second downlink transmission control means for transmitting;
A wireless communication apparatus comprising: The first downlink monitoring period is a transmission period of a predetermined number of sequential packets transmitted by the communication control apparatus to the one wireless communication path at a bandwidth allocation rate determined by the first downlink bandwidth allocation rate determining unit. Corresponding to
The second downlink monitoring period is a transmission period of a predetermined number of packets transmitted by the communication control apparatus to the other wireless communication path at a bandwidth allocation rate determined by the second downlink bandwidth allocation rate determining unit. Corresponding to
The wireless communication apparatus according to claim 4. The first downlink band state determination means calculates a displacement degree of a reception timing of a packet received via the one wireless communication path within the first downlink monitoring period, and calculates the calculated displacement degree. Based on the comparison with the threshold corresponding to the bandwidth allocation rate determined by the first downlink bandwidth allocation rate determining means, determining the downstream bandwidth state in the one wireless communication path,
The second downlink band state determination unit calculates a degree of displacement of a reception timing of a packet received via the other wireless communication path within the second downlink direction monitoring period, and calculates the degree of displacement calculated. And determining a downstream bandwidth state in the other wireless communication path based on a comparison between the second downstream bandwidth allocation ratio determining unit and a threshold value corresponding to the bandwidth allocation ratio determined by the second downlink bandwidth allocation ratio determining unit.
The wireless communication apparatus according to claim 4 or 5, wherein A plurality of different wireless communication paths can be used with the wireless communication device, and the bandwidth that is lacking in one wireless communication path is used for the required bandwidth of the application having real-time characteristics to be used. A communication control method for controlling communication between the wireless communication device and a communication destination,
Determining a bandwidth allocation ratio of packets transmitted by the wireless communication device to the one wireless communication path;
Based on a packet received via the one wireless communication path within a first uplink monitoring period corresponding to the determined bandwidth allocation rate, an upstream band state in the one wireless communication path is determined. Steps,
Transmitting, based on the determination result, first uplink transmission control information for controlling a transmission band of a packet transmitted by the wireless communication apparatus to the one wireless communication path to the wireless communication apparatus;
Determining a bandwidth allocation ratio of packets transmitted by the wireless communication device to the other wireless communication path;
Based on a packet received via the other wireless communication path within a second uplink monitoring period corresponding to the determined bandwidth allocation ratio, an upstream bandwidth state in the other wireless communication path is determined. Steps,
Transmitting, based on the determination result, second uplink transmission control information for controlling a transmission band of a packet transmitted by the wireless communication apparatus to the other wireless communication path to the wireless communication apparatus;
A communication control method characterized by comprising: A plurality of different wireless communication paths can be used with the communication control device, and other wireless communication paths can be used for the bandwidth required by one wireless communication path for the requested bandwidth of the application that has real-time characteristics. And a wireless communication method for wirelessly communicating with a communication destination via the communication control device,
Determining a bandwidth allocation ratio of packets transmitted by the communication control device to the one wireless communication path;
Based on a packet received via the one wireless communication path within a first downlink monitoring period corresponding to the determined bandwidth allocation ratio, a downstream band state in the one wireless communication path is determined. Steps,
Based on the determination result, transmitting to the communication control device first downlink transmission control information for controlling a transmission band of a packet transmitted by the communication control device to the one wireless communication path;
Determining a bandwidth allocation ratio of packets transmitted by the communication control device to the other wireless communication path;
Based on a packet received via the other wireless communication path within a second downlink monitoring period corresponding to the determined bandwidth allocation ratio, a downstream bandwidth state in the other wireless communication path is determined. Steps,
Transmitting, based on the determination result, second downlink transmission control information for controlling a transmission band of a packet transmitted by the communication control device to the other wireless communication path to the communication control device;
A wireless communication method comprising:

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