JP5307493B2 - Wireless communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication device for changing encoding of data accordingly to the change of the header configuration of a radio communication packet so as to be settled in an allowable band upon handover. <P>SOLUTION: The radio communication device includes: a radio communication part (34) for executing radio communication; an encoding part (33) for encoding the data to be transmitted on the basis of a prescribed parameter; a calculation part (36) for calculating the delay time of one way from the present device to a communicating opposite party; a change part (33) for changing the parameter of the encoding part on the basis of the header length to be changed and the delay time calculated by the calculation part when the header length of a radio section is to be changed as the handover is performed; and a control part (33) for executing control so that the encoding part encodes the data to be transmitted on the basis of the changed parameter when the handover is completed. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a radio communication apparatus capable of performing handover between different radio communication networks.

  In recent years, the Internet Engineering Task Force (IETF) has developed an IP mobility technology that enables seamless movement by enabling handover between a plurality of different wireless communication networks such as a mobile phone network and a wireless LAN in order to realize a ubiquitous environment. Is being considered. Specific protocols in this IP mobility technology include Mobile IPv4 and Mobile IPv6 (hereinafter collectively referred to as Mobile IP) that support movement of individual communication terminals, and support movement in units of networks. There is NEMO (Network Mobility).

  By the way, when a communication terminal performs handover between a plurality of wireless communication networks, the header configuration (header length) of a communication packet may change due to handover. The header configuration of the communication packet is, for example, a protocol type (protocol) of each layer such as PPPoE (Point to Point Protocol over Ethernet), IP (Internet Protocol), UDP (User Datagram Protocol), and RTP (Real time Transport Protocol). When the header configuration changes, the size of the entire packet changes according to the change in the header length even if the size of the application data (payload) included in the packet is the same. It will be.

  When the handover source radio communication network and the handover destination radio communication network are different, the header configuration of the communication packet may be different in each radio communication network. In particular, in a mobile IP, when a certain communication terminal moves and is handed over from the original wireless communication network to another wireless communication network, a packet transmitted to the communication terminal is encapsulated by a home agent (HA). Since there is a case where transfer (assignment of an IP address for transfer) is performed, the header configuration of the communication packet is likely to change.

  The communication band that can be used for wireless communication is generally narrower than the communication band that can be used for wired communication. Therefore, in wireless communication, for example, QoS (Quality of Service) control for satisfying a predetermined communication quality is important for an application having real-time characteristics such as VoIP. In such QoS control, an allowable band that can be used for communication is distributed to an application that performs communication. The application that has received the distribution of the allowable bandwidth encodes the application data so as to be within the allowable bandwidth and performs wireless communication (see, for example, Patent Document 1).

JP 2006-500808 A

  However, the encoding method disclosed in Patent Document 1 does not consider changes in the header configuration of communication packets caused by handover. When the communication terminal is handed over and the header configuration (header length) of the communication packet changes due to the handover, the size of the entire communication packet of each application also changes. In particular, in the wireless communication section, since it is easily affected by changes in communication packets, even in the header configuration after handover, even in the header configuration after handover, even application data encoded so as to be within the allowable bandwidth There is a problem that the allowable bandwidth is exceeded.

  Therefore, an object of the present invention made in view of such a point is to change the encoding of application data in accordance with a change in the header configuration of a wireless communication packet so that it can be within an allowable bandwidth in the wireless communication network at the time of handover. An object of the present invention is to provide a wireless communication device that can be used.

The invention of a wireless communication device according to claim 1 that achieves the above object is as follows:
A wireless communication unit that performs wireless communication by connecting to a first wireless communication network and a second wireless communication network different from the first wireless communication network;
A calculation unit for calculating a one-way delay time via the second wireless communication network from the own device to a communication partner;
When the header length of the radio section is changed as the handover from the first radio communication network to the second radio communication network is performed, the changed header length and the second calculated by the calculation unit A changing unit that changes a packet transmission interval based on a delay time of the wireless communication network ;
It is characterized by providing.

Further, the calculation unit calculates a one-way delay time via the second wireless communication network from the communication partner to the own device, and the change unit calculates the one-way delay time and the header length to be changed. If, based on, it is desirable to change the transmission interval of the packet.

  The wireless communication apparatus of the present invention encodes data based on the header length to be changed and the delay time of the handover destination network when the header length of the wireless section is changed with handover. When the handover is completed, the data to be transmitted is controlled to be encoded based on the changed parameter. Therefore, at the time of handover, the header configuration of the radio communication packet is set so as to be within the allowable bandwidth in the radio communication network. It becomes possible to change the encoding of the application data in accordance with the change of.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a communication network that can be used by a wireless communication apparatus according to an embodiment of the present invention. In FIG. 1, it is assumed that a wireless communication device 11 that is a mobile node performs a VoIP call that is a real-time communication system application with a counterpart communication terminal 12 that is an opposite node. The wireless communication device 11 can be handed over between the first wireless communication network 15 and the second wireless communication network 16. The first wireless communication network 15 and the second wireless communication network 16 are coupled to the Internet 18 via a packet network 17.

  Here, the first wireless communication network 15 is made of, for example, cdma2000 EV-DO, and the second wireless communication network 16 is made of, for example, an LTE (Long Term Evolution) mobile phone network. In FIG. 1, reference numeral 15 a indicates an access point of the first wireless communication network 15, and reference numeral 16 a indicates a base station of the second wireless communication network 16. Reference numeral 15a means a base station installed on the service side for connection to the network, and is not limited to an access point. Therefore, hereinafter, the symbol 15a may be referred to as a base station.

  For example, the partner communication terminal 12 includes a personal computer to which a handset 12a is connected and a softphone is installed, and is connected to the Internet 18 through an Internet service provider (not shown).

  Further, SIP (Session Initiation Protocol) servers 21 and 22 for controlling communication are connected to the packet network 17 and the Internet 18, respectively. Further, a home agent (HA) 23 is connected to the Internet 18 for transferring a received packet addressed to the wireless communication device 11 to a wireless communication network to which the wireless communication device 11 is connected.

  In the communication network shown in FIG. 1, the home address used in the wireless communication network to which the wireless communication device 11 originally belongs is registered in the HA 23, and the care-of address of the handover destination wireless communication network is registered at the time of handover. Thus, handover between different wireless communication networks is possible. Note that such IP mobility technology is well known in the above-described mobile IP and NEMO, and thus detailed description thereof is omitted here.

  In the present embodiment, the wireless communication device 11 registers the IP address of the first wireless communication network 15 in the HA 23 as a care-of address (first wireless CoA), and the partner communication terminal 12 via the first wireless communication network 15. It is assumed that the handover to the second wireless communication network 16 is performed from the state where communication is performed with the second wireless communication network 16.

  FIG. 2 is a functional block diagram showing a schematic configuration of radio communication apparatus 11 according to the present embodiment shown in FIG. The wireless communication device 11 executes a first wireless I / F (interface) 31 corresponding to the first wireless communication network 15, a second wireless I / F 32 corresponding to the second wireless communication network 16, and a VoIP application. A telephone function unit 33 constituting an execution unit, a communication processing unit 34 for controlling connection to the first wireless communication network 15 and the second wireless communication network 16, and the first wireless communication network 15 and the second wireless communication network 16. A wireless information acquisition unit 35 that acquires wireless information, a handover control unit 36 that controls a handover between the first wireless communication network 15 and the second wireless communication network 16, and distribution of a wireless band for applications such as VoIP A QoS control unit 39 for performing

  The communication processing unit 34 constitutes a wireless communication unit that performs wireless communication. Between the telephone function unit 33 and the counterpart communication terminal 12, the first wireless communication network 15 or the second wireless communication network 16 is used. While making a call, the connection of the first wireless I / F 31 or the second wireless I / F 32 is controlled so as to communicate with the HA 23 under the control of the handover control unit 36.

  The wireless information acquisition unit 35 acquires the communication quality of the corresponding first wireless communication network 15 and second wireless communication network 16 and the header configuration of the wireless communication packet from the first wireless I / F 31 and the second wireless I / F 32, respectively. Then, the acquired communication quality and header configuration are supplied to the handover control unit 36, and the communication quality of the first wireless communication network 15 currently used for the call is supplied to the telephone function unit 33. Here, as the communication quality, for example, an RSSI (Received Signal Strength Indicator) representing a radio state is acquired. Note that the wireless state of the second wireless communication network 16 that is not used for a call is acquired by receiving broadcast information transmitted from the base station 16a, for example.

  In addition, the wireless information acquisition unit 35 receives allowable bandwidth information for communication applications (communication in the first wireless communication network 15 and the second wireless communication network 16 respectively corresponding to the first wireless I / F 31 and the second wireless I / F 32). Obtain the bandwidth that the application can use. Such allowable bandwidth information is managed by each base station such as the base station (access point) 15a of the first wireless communication network 15 and the base station 16a of the second wireless communication network 16, or the base station (access point). ) May be managed by an information server (not shown) that collectively manages a plurality of base stations such as 15a and base station 16a. When the permissible bandwidth information is not managed by the base stations 15a and 16a or the information server and there is no permissible bandwidth information that can be used, the radio information acquisition unit 35 performs the first radio I / F 31 and the second radio I. Retained in advance based on the reception strength (RSSI) at / F32 and the number of radio slots (number of logical channels) allocated from the base station 15a and the base station 16a to the first radio I / F 31 and the second radio I / F 32 Approximate allowable bandwidth information can be obtained by referring to a lookup table or the like. The wireless information acquisition unit 35 supplies the acquired allowable bandwidth information to the QoS control unit 39.

  Based on the allowable bandwidth information supplied from the wireless information acquisition unit 35, the QoS control unit 39 distributes the upstream / downstream allowable bandwidth to communication applications such as a VoIP application and a streaming application such as video. For example, the QoS control unit 39 divides communication applications into real-time applications (such as VoIP) and non-real-time applications (such as Web access / FTP), and distributes the allowable bandwidth preferentially to the real-time applications. Therefore, it is possible to perform communication control suitable for a predetermined communication quality (for example, low delay, wide band) for each application. The QoS control unit 39 notifies the telephone function unit 33 of the allowable bandwidth distributed to the VoIP application.

  The handover control unit 36 determines whether or not to schedule handover during connection to the first wireless communication network 15, that is, whether or not to start preparation for handover. For this reason, the handover control unit 36 monitors the respective radio states (communication quality) of the first radio communication network 15 and the second radio communication network 16 acquired from the radio information acquisition unit 35, and forms a radio link. The wireless state of the first wireless communication network 15 that is making a call becomes worse than a preset handover schedule determination threshold in the first wireless communication network 15 and the wireless state of the second wireless communication network 16 is determined to be a handover schedule. When the threshold value is exceeded, the handover schedule to the second wireless communication network 16 is determined, that is, the start of handover preparation is determined.

  In addition, the handover control unit 36 measures the uplink / downlink absolute delay time Tdup1 / Tddn1 of the handover source in the handover source radio communication network (here, the first radio communication network 15), and further determines the handover schedule. Then, the handover destination uplink / downlink absolute delay time Tdup2 / Tddn2 in the handover destination radio communication network (here, the second radio communication network 16) is measured. The handover control unit 36 supplies these information and the header configuration of the wireless communication packet supplied from the wireless information acquisition unit 35 to the telephone function unit 33 as required handover information. Therefore, in the present embodiment, the handover control unit 36 constitutes a calculation unit that calculates the one-way delay time via the wireless communication network from the own device (wireless communication device 11) to the communication partner (partner communication terminal 12). doing.

  Next, a method of acquiring the handover source uplink / downlink absolute delay time Tdup1 / Tddn1 and the handover destination uplink / downlink absolute delay time Tdup2 / Tddn2 by the handover control unit 36 will be described.

(Acquisition method of absolute delay time Tdup1 / Tddn1, Tdup2 / Tddn2)
The handover control unit 36 determines whether the handover source uplink / downlink absolute delay time Tdup1 / Tddn1 and the handover destination uplink / downlink absolute delay time Tdup2 / Tddn2 are, for example, any of the first to fourth absolute delay time acquisition methods described below. Get by.

(A) First Absolute Delay Time Acquisition Method Control of the telephone function unit 33 and / or the communication processing unit 34, and the measurement packet having a transmission time stamp with respect to the HA 23 time-synchronized with the wireless communication device 11 Requesting transmission, thereby causing the HA 23 to transmit a measurement packet to both the first wireless communication network 15 and the second wireless communication network 16. The wireless communication device 11 receives the measurement packet transmitted from the HA 23 via the corresponding first wireless I / F 31 and second wireless I / F 32, respectively, and based on the reception time and the time stamp of the measurement packet. Then, the uplink / downlink absolute delay times Tdup1 / Tddn1 and Tdup2 / Tddn2 of the corresponding network are measured. When the absolute downlink delay time of the handover source wireless communication network can be measured from the received packet during a call, transmission of the measurement packet to the wireless communication network can be omitted.

(B) Second Absolute Delay Time Acquisition Method The telephone function unit 33 and / or the communication processing unit 34 is controlled to notify the HA 23 that is time-synchronized with the wireless communication device 11, thereby Similar to the first absolute delay time acquisition method, the HA 23 transmits a measurement packet to both the first wireless communication network 15 and the second wireless communication network 16, and the uplink / downlink absolute delay time of the corresponding network. Tdup1 / Tddn1 and Tdup2 / Tddn2 are measured.

(C) Third Absolute Delay Time Obtaining Method The telephone function unit 33 and / or the communication processing unit 34 are controlled so that the first wireless communication device 11 performs first synchronization with the HA 23 that is time-synchronized with the wireless communication device 11. Transmitting measurement packets such as PING and RTCP from both the wireless communication network 15 and the second wireless communication network 16 and receiving the reply, and the uplink / downlink absolute delay times Tdup1 / Tddn1 and Tdup2 / of the corresponding network Measure Tddn2.

  In the above (a) to (c), since the network between the counterpart communication terminal (CN) 12 and the HA 23 is not switched, the absolute delay time between them is not considered.

(D) Fourth Absolute Delay Time Acquisition Method The downlink absolute delay time of each wireless communication network is acquired using the handover technique studied in IEEE 802.21. In IEEE 802.21 (Media Independent Handover (MIH)), as a handover technique between different types of wireless communication networks (WiFi, WiMAX, mobile phones, etc.), a means for controlling handover (in FIG. 2, the handover control unit 36) is an MIH user. It is considered that MIHF (MIH Function) acquires wireless information of a communication device based on a request from the MIH user and provides it to the MIH user. It is also considered that an MIH user acquires information from an information server in a connected network through MIHF in his / her terminal.

  FIG. 3 is a diagram for explaining the fourth absolute delay time acquisition method. In FIG. 3, a first wireless communication network 15 and a second wireless communication network 16 are connected to a backbone network 60 constituting the Internet 18 together with other wireless communication networks, and measurement for measuring delay time in the backbone network 60 is performed. Server 61 is directly connected. A first information server 62 is connected to the first wireless communication network 15, and a second information server 63 is connected to the second wireless communication network 16. The partner communication terminal 12 is connected to the backbone network 60 via the provider 65.

  The first information server 62 uses the one-way network delay reference time Tn1 from the measurement server 61 to the access point 15a as a reference for delay time measurement, and the wireless communication apparatus connected to the access point 15a from the access point 15a. The upper and lower radio delay reference times Trup1 and Trdn1 are held. Similarly, the second information server 63 uses a one-way network delay reference time Tn2 from the measurement server 61 to the base station 16a as a reference for delay time measurement, and a radio connected from the base station 16a to the base station 16a. The upper and lower radio delay reference times Trup2 and Trdn2 to the communication device are held.

  Here, the network delay reference times Tn1 and Tn2 are transmitted / received between the access point 15a and the measurement server 61, and between the base station 16a and the measurement server 61, respectively (such as PING and RTCP). The round trip time is measured, and the round trip time is halved.

  The upper and lower radio delay reference times Trup1 and Trdn1 in the first radio communication network 15 send packets from the access point 15a to the radio communication apparatus connected to the access point 15a and time-synchronized with the access point 15a. The wireless communication device that has received the packet records the received time and sends back the packet, thereby calculating each of the uplink and downlink delay times.

  Similarly, the upper and lower radio delay reference times Trup2 and Trdn2 in the second radio communication network 16 send packets from the base station 16a to the radio communication apparatus connected to the base station 16a and time-synchronized with the base station 16a. The wireless communication apparatus that has received the packet records the received time and sends back the packet, thereby calculating each of the upstream and downstream delay times.

  When connecting to the first wireless communication network 15, the handover control unit 36 transmits the network delay reference time Tn1 and the wireless delay reference time from the first information server 62 connected to the first wireless communication network 15 via MIHF. Get Trdn1 and Trup1. In addition, the handover control unit 36 transmits / receives a packet to / from the other party (here, the other communication terminal 12 that is not time-synchronized with the wireless communication apparatus 11) for which the delay time is to be measured. The round trip time (Tn3 + Trdn3 + Tn3 + Trup3) is measured. From this value, the one-way delay time (Tn3-Tn1) between the partner communication terminal 12 and the measurement server 61 is obtained as follows, and the handover between the wireless communication device 11 and the partner communication terminal 12 is performed. Tn3 + Trdn3 corresponding to the original downlink absolute delay time Tddn1 is calculated.

[Equation 1]
Tn3-Tn1 = {(Tn3 + Trdn3 + Tn3 + Trup3)-(Tn1 + Trdn1 + Tn1 + Trup1)} / 2
Tddn1 = Tn3 + Trdn3 = Tn1 + Trdn1 + (Tn3-Tn1)

  Tn3 + Trup3 corresponding to the handover source upstream absolute delay time Tdup1 between the wireless communication device 11 and the counterpart communication terminal 12 can be obtained by Tdup1 = Tn3 + Trup3 = Tn1 + Trup1 + (Tn3-Tn1). .

  Further, when the handover control unit 36 determines the handover schedule, the handover control unit 36 acquires the network delay reference time Tn2 and the radio delay reference time Trdn2 of the handover destination, and therefore the first information server of the first wireless communication network 15 currently connected to the handover control unit 36. The location information of the wireless communication device 11 is transmitted to the second information server 63 of the second wireless communication network 16 that is the handover destination via 62, and the network delay reference time Tn2 and the wireless delay reference time Trdn2 are returned. Request. As a result, the second information server 63 determines the network delay reference time Tn2 and the radio delay reference time Trdn2 of the base station 16a considered to be connected in consideration of the position information and the number of connected users of each base station. 1 It returns to the wireless communication device 11 via the information server 62.

  The handover controller 36 receives the handover destination network delay reference time Tn2 and the radio delay reference time Trdn2 returned from the second information server 63, and uses the obtained information and the calculated (Tn3-Tn1), In the following manner, Tn4 + Trdn4 corresponding to the handover destination downlink absolute delay time Tddn2 between the wireless communication apparatus 11 and the counterpart communication terminal 12 is calculated.

[Equation 2]
Tddn2 = Tn4 + Trdn4 = (Tn2 + Trdn2) + (Tn3-Tn1)

  Note that the handover control unit 36 also requests the second information server 63 to return the wireless delay reference time Trup2, which corresponds to the handover destination uplink absolute delay time Tdup2 between the wireless communication device 11 and the counterpart communication terminal 12. Tn4 + Trup4 can be obtained by Tdup2 = Tn4 + Trup4 = (Tn2 + Trup2) + (Tn3-Tn1).

  The uplink / downlink absolute delay times Tdup1 / Tddn1 and Tdup2 / Tddn2 acquired by any one of the first to fourth absolute delay time acquisition methods described above together with the downlink absolute delay times acquired in the same manner for other wireless communication networks. For each wireless communication network, it is stored in a memory (not shown) in the handover control unit 36 and supplied to the telephone function unit 33.

  As described above, the handover control unit 36 acquires information including handover schedule determination information, handover source uplink / downlink absolute delay times Tdup1 / Tddn1, and handover destination uplink / downlink absolute delay times Tdup2 / Tddn2. Is supplied to the telephone function unit 33.

  Further, when determining the handover schedule, the handover control unit 36 controls the communication processing unit 34 to connect the second wireless I / F 32 to the second wireless communication network 16. Thereafter, the handover control unit 36 sends a Registration Request (Binding Update in NEMO) to the HA 23 via the second wireless communication network 16 that is the handover destination, and registers the care-of address of the handover destination in the HA 23. To do.

  At that time, the handover control unit 36 sets 8 bits of the Registration Request Field of the Registration Request message in the communication processing unit 34 (in NEMO, multiple care of address is used), and the first radio communication network 15 also uses the second radio. The communication network 16 can also communicate.

  After that, when receiving the Registration Reply (Binding Acknowledge in NEMO), which is the handover completion information returned from the HA 23, the handover control unit 36 cancels the registration of the care-of address of the first wireless communication network 15 that is the handover source, and connects After that, the communication processing unit 34 is controlled to continue the VoIP application via the second wireless communication network 16 that is the handover destination, and the received handover completion information is supplied to the telephone function unit 33.

  The telephone function unit 33 is an execution unit of a soft phone such as a VoIP application, and is supplied from the QoS control unit 39 and the header configuration of the wireless communication packet supplied from the handover control unit 36 and the absolute delay time of each wireless communication network. On the basis of the permissible bandwidth, voice data encoding parameters for VoIP applications are set and voice data is encoded. The telephone function unit 33 sets a speech encoding parameter every time a handover notification is received from the handover control unit 36.

  From the header configuration of the wireless communication packet and the absolute delay time of each wireless communication network, the telephone function unit 33 determines the audio data encoding control tables (that is, parameters used for the audio encoding) of the wireless communication device 11 and the counterpart communication terminal 12. And the encoding control table of the counterpart communication terminal 12 is sent to the counterpart communication terminal 12 through the first radio I / F 31 or the second radio I / F 32. Next, the telephone function unit 33 sets the voice coding rate of the own device from the coding control table of the wireless communication device 11 based on the allowable bandwidth of the uplink, and the partner communication terminal 12 sets the allowable bandwidth of the downlink by the partner communication terminal 12. Based on the permissible downlink bandwidth, the partner communication terminal 12 is notified through the first wireless I / F 31 or the second wireless I / F 32 so that the voice coding rate can be set from the coding control table of the partner communication terminal 12. Therefore, in the present embodiment, the telephone function unit 33 includes an encoding unit that encodes data to be transmitted based on a predetermined parameter, and when the header length of the radio section is changed as a result of handover, Based on the header length to be changed and the delay time of the handover destination radio communication network, the change unit for changing the parameters of the encoding unit, and when the handover to the handover destination radio communication network is completed, the encoding unit And a control unit that controls to encode data to be transmitted based on the changed parameter.

  FIG. 6 is a diagram illustrating an example of a header configuration of a radio communication packet in each communication section when IP mobility is realized by mobile IPv4 (without reburst tunneling). In FIG. 6, the header configuration (header length) of the communication packet in the second wireless communication network is a configuration in which PPPoE is added to the header configuration of the communication packet in the first wireless communication network. Note that reburst tunneling is one of packet transfer options in mobile IP. When the reburst tunneling option is invalid (no reburst tunneling), communication packets from the wireless communication device 11 to the partner communication terminal 12 are transmitted. Is transmitted directly to the partner communication terminal 12 without going through the HA 23. When the reburst tunneling option is valid (with reburst tunneling), the communication packet from the wireless communication apparatus 11 to the partner communication terminal 12 is transmitted to the partner communication terminal 12 via the HA 23. Note that a communication packet from the counterpart communication terminal 12 to the wireless communication device 11 is transmitted to the wireless communication device 11 via the HA 23 regardless of the presence or absence of reburst tunneling.

  FIG. 7 is a diagram illustrating a header configuration of an upstream communication packet transmitted from the wireless communication device 11 to the counterpart communication terminal 12 in FIG. 6, and FIG. 7A illustrates a case where the packet passes through the first wireless communication network 15. FIG. 7B shows the header configuration when passing through the second wireless communication network 16. When there is no reburst tunneling, a packet from the wireless communication apparatus 11 to the partner communication terminal 12 is directly sent to the partner communication terminal 12 (without going through the HA 23). For this reason, the header length of the packet from the wireless communication device 11 to the counterpart communication terminal 12 is Ether (14) + IPv4 (20) + UDP (8) as shown in FIG. ) + RTP (12), which is a total of 54 bytes, and when passing through the second wireless network 16, as shown in FIG. 7B, the total is 60 bytes including PPPoE (6).

  FIG. 8 is a diagram illustrating a header configuration of a downlink communication packet transmitted from the HA 23 to the radio communication device 11 in FIG. 6, and FIG. 8A is a header configuration when passing through the first radio communication network 15. FIG. 8B shows a header configuration when passing through the second wireless communication network 16. When there is no reburst tunneling, the destination of the packet from the partner communication terminal 12 to the wireless communication device 11 is the home address of the wireless communication device 11, so that it is sent to the wireless communication device 11 once via the HA 23. Therefore, the header length of the packet from the partner communication terminal 12 to the HA 23 is a total of 54 bytes of Ether (14) + IPv4 (20) + UDP (8) + RTP (12), but the packet is encapsulated by the HA 23 (wireless communication). Since the IP address of the device 11 is given), when passing through the first wireless communication network, as shown in FIG. 8 (a), the total becomes 74 bytes including IPv4 (20), and the second wireless In the case of passing through the network 16, as shown in FIG. 8B, a total of 80 bytes including PPPoE (6) is added.

  As described above, the header configuration of the wireless communication packet transmitted and received by the wireless communication device 11 differs between upstream and downstream, and before and after handover (between the first wireless communication network and the second wireless communication network). The allowable bandwidth distributed to the telephone function unit 33 by the QoS control unit 39 is not only for the payload including the encoded voice data but also for the entire packet including the above header configuration. In some cases, the size of the entire packet changes, and the amount of audio data may exceed the allowable bandwidth.

FIG. 5 is a diagram showing an operation flow of the wireless communication device 11 according to the embodiment of the present invention.
Hereinafter, the details of the operation flow shown in FIG. 5 will be described using the header configuration of the network and wireless communication packet shown in FIG. 6 as an example. In FIG. 6, it is assumed that the wireless communication device 11 performs wireless communication, but the counterpart communication terminal 12 performs wired communication. In FIG. 6, the counterpart communication terminal 12 includes a telephone function unit 53 that is an execution unit of a softphone such as a VoIP application, and the telephone function unit 53 performs encoding control sent from the wireless communication apparatus 11. Based on the table, the coding rate of the audio data for the wireless communication device 11 from the own terminal (the partner communication terminal 12) is set. Further, it is assumed that the uplink / downlink absolute delay time in the first radio communication network is 200/100 msec, and the uplink / downlink absolute delay time in the second radio communication network is 50/50 msec, respectively.

  In the operation flow shown in FIG. 5, the telephone function unit 33 of the wireless communication device 11 first acquires the wireless information of the first wireless communication network 15 currently connected from the handover control unit 36. The radio information acquired by the telephone function unit 33 includes the absolute delay time of uplink / downlink to the counterpart communication terminal 12 via the first radio communication network 15 and the header of the uplink / downlink communication packet in the first radio communication network 15. Long and included.

  The telephone function unit 33 is used for encoding the voice data from the wireless communication device 11 to the partner communication terminal 12 (wireless communication device) based on the acquired absolute absolute delay time and the header length of the upstream communication packet. 11) A coding control table is generated, and the partner used for coding the voice data from the partner communication terminal 12 to the wireless communication device 11 based on the obtained downlink absolute delay time and the header length of the downlink communication packet. A terminal (partner communication terminal 12) encoding control table is generated.

  FIG. 9 is a flowchart for generating an encoding control table by the telephone function unit 33. First, the telephone function unit 33 generates an upstream / downstream encoding rate table in the first wireless communication network 15, which is a basis for generating an encoding control table, based on the acquired header length (steps S101 and S102). . FIG. 11A is a diagram showing an upstream coding rate table in the first wireless communication network 15, and FIG. 13A is a diagram showing a downstream coding rate table in the first wireless communication network 15. is there. The telephone function unit 33 creates the coding rate table shown in FIGS. 11 and 13 according to the header length and the packet transmission interval, based on the reference coding rate table shown in FIG. However, for example, according to the type of the wireless communication network, the coding rate table can be held in the apparatus in advance.

  The coding rate table shown in FIG. 11 and FIG. 13 includes the data amount [bps] of the voice packet per second (header and payload) based on the packet transmission interval (20/40/60 msec) and the voice quality (Quality). Included). The higher the voice quality (1: lowest to 10: highest, the reference rate is 4), the larger the data amount, and the longer the packet transmission interval (20 ms: shortest to 60 ms: longest), the transmission data amount. Since the ratio indicated by the header decreases, the amount of data communication decreases. For example, when comparing voice data for 1 second in packets with a 20 ms interval and transmission with packets with a 40 ms interval, the number of packets is 50 for a 20 ms interval, and the packet is for 40 ms. The number will be 25. In this case, assuming that the header length of each packet is constant, sending a packet at intervals of 40 ms is a header to be sent for voice data of the same time for 25 packets (50-25 = 25) compared to 20 ms. The total amount of information can be reduced. That is, the telephone function unit 33 can increase the ratio of payload (voice data) to the entire transmission data by transmitting voice packets at as long time intervals as possible. Note that when the transmission interval of voice packets is long, the influence on the reproduction quality of voice data given by one packet loss also increases. For example, when the allowable bandwidth of the wireless section is sufficiently large, the transmission interval is reduced. Note that even a wireless communication network that can be long, it is conceivable to transmit voice packets at short transmission intervals.

Next, the telephone function unit 33 acquires the absolute delay time of uplink / downlink to the partner communication terminal 12 via the first wireless communication network 15 (step S103), and the own device (wireless communication device 11) and the partner terminal In order to determine how long (the partner communication terminal 12) can increase the transmission interval of voice packets, that is, for how long a packet can be accumulated in the terminal, the accumulable time (Tdlypkc ) Is calculated (step S104). The accumulation time (Tdlypkc) is the delay time (Tdlyprm) allowable for communication application reproduction and the jitter buffer dwell time (Tdlyjtr) from when the reproduction terminal receives the data packet until actual reproduction as shown in Equation 3. And the obtained absolute delay time (Tdlynet) and voice packet encoding / decoding time (Tdlyenc). Since the calculation of Formula 3 is performed for the absolute delay times for uplink and downlink, the accumulable time (Tdlypkc) for each of uplink and downlink is calculated. The uplink accumulative time (Tdlypkc) indicates the transmission interval of voice packets from the own device (wireless communication device 11) to the partner terminal (partner communication terminal 12), and the downlink accumulative time (Tdlypkc) is It shows the transmission interval of voice packets from the partner terminal (partner communication terminal 12) to the own apparatus (wireless communication apparatus 11).
[Equation 3]
Tdlypkc ＝ Tdlyprm-Tdlyjtr-Tdlynet-Tdlynec

  In FIG. 6, the uplink / downlink absolute delay time (Tdlypkc) in the first wireless communication network is 200/100 msec, the delay time (Tdlyprm) allowable for reproduction of the communication application is 400 ms, and the jitter buffer residence time (Tdlyjtr). ) Is 160 ms, and the voice packet encoding / decoding time (Tdlyenc) is 20 ms. Therefore, the upstream accumulative time (Tdlypkc) is 20 ms (Tdlypkc = 400-160-200-20 = 20), and the downstream accumulative time (Tdlypkc) is 120 ms (Tdlypkc = 400-160-100-20 = 120). It becomes.

  In step S104, when the up / down accumulation time (Tdlypkc) is calculated, the telephone function unit 33 uses the up / down coding rate table and the up / down accumulation time (Tdlypkc). Then, the own device coding control table used by the wireless communication device 11 and the partner terminal coding control table used by the partner communication terminal 12 are created (steps S105 to S112). FIG. 12A and FIG. 14A are diagrams showing coding control tables for the own device and the counterpart terminal in the first wireless communication network, respectively.

  When the accumulation possible time (Tdlypkc) is 60 ms or more (Yes in step S105), the telephone function unit 33 encodes the audio data according to the most efficient 60 ms column of the encoding rate table so that the audio data is encoded in 60 ms. Each entry in the column is registered in the encoding control table (step S106). In the case of FIG. 6, since the downlink accumulative time (Tdlypkc) is 120 ms, as shown in FIG. 14 (a), the partner terminal coding control table includes the coding rate table of FIG. 13 (a). Each entry in the 60 ms column is registered.

  When the possible storage time (Tdlypkc) is less than 60 ms (No in step S105), but when it is 40 ms or more (Yes in step S107), the telephone function unit 33 sets the next most efficient 40 ms in the coding rate table to 60 ms. Each entry in the 40 ms column is registered in the encoding control table so that the audio data is encoded according to the column (step S108).

  If the possible storage time (Tdlypkc) is less than 40 ms (No in step S107), but 20 ms or more (Yes in step S109), the telephone function unit 33 first encodes the audio data according to the 20 ms column. . Of the 20 ms column, an entry having a reference rate (Quality = 4) or higher is registered in the encoding control table (step S111). Next, the telephone function unit 33 does not register the entry below the reference rate in the 20 ms column, moves to the 40 ms column, moves to the 40 ms column, and sets the 20 ms reference rate among the 40 ms column entries. (For example, in FIG. 11A, the bit rate of the entry of Quality 6 or lower is lower than 34,400 bps) in the encoding control table. Register (step S112). In voice communication, while it is necessary to maintain desired communication quality (above the reference rate), it is not a good idea to transmit packets at 20 ms intervals with poor communication efficiency in an allowable band where communication quality cannot be maintained. Therefore, this is a measure for improving the voice communication quality at the expense of reproduction delay. In the case of FIG. 6, since the uplink accumulative time (Tdlypkc) is 20 ms, as shown in FIG. 12 (a), the coding rate table of FIG. An entry with a quality of 10 to 4 is registered in the 20 ms column, and then an entry with a quality of 6 to 1 in the 40 ms column is registered.

  If the accumulable time is less than 20 ms (step), each entry in the 20 ms column is registered in the encoding control table so that the audio data is encoded according to the 20 ms column (step S110).

  FIG. 10 is an encoding control table generation flowchart different from FIG. Note that the processing in steps S201 to S204 and S214 to S217 in the flowchart shown in FIG. 10 is the same as the processing in steps S101 to S104 and S109 to S112 in the flowchart shown in FIG.

  In step S205, when the accumulable time (Tdlypkc) is 60 ms or more, the telephone function unit 33 acquires an allowable bandwidth (Bprm) from the QoS control unit 39 (step S206). When the acquired allowable bandwidth (Bprm) is equal to or greater than the predetermined bandwidth (Bth), that is, when the wireless section is sufficiently wide, the telephone function unit 33 encodes audio data according to a 20 ms string. As described above, each entry in the 20 ms column is registered in the encoding control table (step S208). This is because, when the transmission interval of voice packets is long, the influence on the reproduction quality of the voice data given by one packet loss also becomes large. For example, when the allowable bandwidth of the radio section is sufficiently large, the transmission interval This is because it is better to transmit voice packets at a short transmission interval even in a wireless communication network that can lengthen the time. If the wireless section is not wideband, each entry in the 60 ms column is registered in the encoding control table (step S209).

  In step S210, when the accumulable time (Tdlypkc) is 40 ms or more, the telephone function unit 33 acquires an allowable bandwidth (Bprm) from the QoS control unit 39 (step S211). When the acquired allowable bandwidth (Bprm) is equal to or greater than the predetermined bandwidth (Bth), that is, when the wireless section is sufficiently wide, the telephone function unit 33 encodes audio data according to a 20 ms string. As described above, each entry in the 20 ms column is registered in the encoding control table (step S208). If the wireless section is not wideband, the telephone function unit 33 registers each entry in the 40 ms column in the encoding control table (step S213).

  When the telephone function unit 33 generates the partner terminal coding control table, the telephone function unit 33 sends the partner terminal coding control table to the partner communication terminal 12.

  Next, the telephone function unit 33 acquires the allowable uplink / downlink bandwidth distributed to the VoIP application from the QoS control unit 39, and notifies the partner communication terminal 12 of the allowable downlink bandwidth. The telephone function unit 33 obtains a coding rate suitable for the permissible band from the coding control table for its own device shown in FIG. 12A based on the permissible upstream band, and the voice corresponding to the coding rate. The packet is transmitted to the partner communication terminal 12. As for the downlink allowable band notified from the telephone function unit 33 of the wireless communication device 11 to the counterpart communication terminal 12, for example, a radio state change according to the transmission delay time between the radio communication device 11 and the counterpart communication terminal 12 is performed. Considering this, it is also conceivable to use the average value of the permissible downlink bandwidth acquired during a certain time or use the lowest value among the permissible downlink bandwidths acquired during a certain time.

  The telephone function unit 53 of the counterpart communication terminal 12 uses the code that matches the allowable band based on the allowable downlink band notified from the telephone function unit 33 of the wireless communication apparatus 11 based on the encoding control table shown in FIG. An encoding rate is acquired, and a voice packet corresponding to the encoding rate is transmitted to the wireless communication apparatus 11.

  While the wireless communication device 11 and the counterpart communication terminal 12 are communicating via the first wireless communication network, the handover control unit 36 receives the first wireless communication network 15 acquired from the wireless information acquisition unit 35 and Each wireless state (communication quality) of the second wireless communication network 16 is monitored, and the wireless state of the first wireless communication network 15 that is making a call by forming a wireless link is set in advance to the first wireless communication network. 15, the handover schedule to the second wireless communication network 16 is determined when the handover schedule determination threshold is worse than 15 and the wireless state of the second wireless communication network 16 is equal to or greater than the handover schedule determination threshold.

  When determining the handover schedule, the handover control unit 36 notifies the telephone function unit 33 of the start of the handover. In response to the notification, the telephone function unit 33 acquires the wireless information of the second wireless communication network 16 that is the handover destination from the handover control unit 36. The radio information acquired by the telephone function unit 33 includes the absolute delay time of uplink / downlink to the counterpart communication terminal 12 via the second radio communication network 16 and the uplink / downlink communication packets in the second radio communication network 16. Contains the header length. However, until the handover control unit 36 completes the handover, it may not be possible to acquire the wireless information of the second wireless communication network 16 that is the handover destination. The temporary wireless information that is held is used. The provisional wireless information includes provisional downlink absolute delay time to the partner communication terminal 12 via the second wireless communication network 16 and provisional downlink packet header length in the second wireless communication network 16. In the following description, it is assumed that the telephone function unit 33 performs processing based on temporary wireless information.

  First, the telephone function unit 33 uses the temporary downlink absolute delay time and the temporary downlink packet header length to encode the voice data from the counterpart communication terminal 12 to the radio communication device 11. Generate a table.

  The encoding control table is created according to the flowchart shown in FIG. In step S102, the telephone function unit 33 creates a downlink coding rate table in the second wireless communication network 16 shown in FIG. Here, assuming that the provisional downlink absolute delay time is 50 ms, the accumulable time (Tdlypkc) calculated in step S104 is 170 ms. Therefore, as shown in FIG. 14B, each entry in the 60 ms column of the coding rate table in FIG. 13B is registered as it is in the partner terminal coding control table in the second wireless communication network. (Step S106).

  When the telephone function unit 33 generates the partner terminal coding control table, the telephone function unit 33 sends the partner terminal coding control table to the partner communication terminal 12.

  When the telephone function unit 53 of the counterpart communication terminal 12 receives the counterpart terminal encoding control table from the radio communication device 11, the counterpart terminal encoding control table in the handover source radio communication network (first radio communication network) Thus, two coding control tables, that is, the coding control table for the partner terminal in the handover destination radio communication network (second radio communication network) are held. The telephone function unit 53 of the partner communication terminal 12 controls the encoding control with the shorter packet size out of the two encoding control tables so that the packet size does not exceed the allowable bandwidth when the radio communication network is switched by the handover. The audio data is encoded using the table.

  When the handover is completed, the handover control unit 36 notifies the telephone function unit 33 of the completion of the handover. The telephone function unit 33 notifies the counterpart communication terminal 12 of the handover notification. Upon receiving the handover notification, the telephone function unit 53 of the counterpart communication terminal 12 discards the counterpart terminal encoding control table in the handover source radio communication network (first radio communication network), and encodes subsequent audio data. Is performed using the partner terminal coding control table in the handover destination radio communication network (second radio communication network).

  The telephone function unit 33 acquires the wireless information of the second wireless communication network 16 that is the handover destination from the handover control unit 36 in response to the handover completion notification. The radio information acquired by the telephone function unit 33 includes the absolute delay time of uplink / downlink to the counterpart communication terminal 12 via the second radio communication network 16 and the uplink / downlink communication packets in the second radio communication network 16. Contains the header length. Based on the acquired uplink absolute delay time and the header length of the uplink packet, the telephone function unit 33 is used for encoding the voice data from the wireless communication apparatus 11 to the partner communication terminal 12 based on the acquired uplink absolute delay time and the uplink packet header length. Generate a table. Note that the provisional wireless information held by the telephone function unit 33 (the provisional downlink absolute delay time to the partner communication terminal 12 via the second wireless communication network 16 and the first 2 is a temporary downlink packet header length in the wireless communication network 16) and the actually acquired radio information differs from the telephone function unit 33, the acquired downlink absolute delay time and the downlink packet header length acquired again. Based on the above, a partner terminal coding control table is created and sent to the partner communication terminal 12.

  The encoding control table is created according to the flowchart shown in FIG. In step S102, the telephone function unit 33 creates an upstream coding rate table in the second wireless communication network 15 shown in FIG. In FIG. 6, since the absolute uplink delay time of the second wireless communication network is 50 ms, the accumulable time (Tdlypkc) calculated in step S104 is 170 ms. Therefore, as shown in FIG. 12B, each entry in the 60 ms column of the coding rate table in FIG. 11B is registered as it is in the own device coding control table in the second wireless communication network. (Step S106).

  Next, the telephone function unit 33 acquires the allowable uplink / downlink bandwidth distributed to the VoIP application from the QoS control unit 39, and notifies the partner communication terminal 12 of the allowable downlink bandwidth. The telephone function unit 33 acquires an encoding rate that matches the allowable band from the own apparatus encoding control table in the second wireless communication network 16 shown in FIG. A voice packet corresponding to the coding rate is transmitted to the partner communication terminal 12. The telephone function unit 53 of the partner communication terminal 12 uses the encoding control table in the second wireless communication network 16 shown in FIG. 14B based on the allowable downlink bandwidth notified from the telephone function unit 33 of the wireless communication device 11. Then, an encoding rate suitable for the allowable band is acquired, and a voice packet corresponding to the encoding rate is transmitted to the wireless communication apparatus 11.

  Thus, according to the present embodiment, when the header length of the radio section is changed as the handover is performed, the radio communication device 11 and the delay time of the handover destination network are changed. Based on the above, the coding control table is changed, and when handover is completed, the transmission data is controlled to be coded based on the changed coding control table. It is possible to change the encoding of the application data in accordance with the change in the header configuration of the wireless communication packet so that it can be accommodated.

  Also, the wireless communication device 11 calculates a one-way delay time from the own device to the partner communication terminal 12 via the second wireless communication network 16, and the one-way delay time and the header length changed with the handover Based on the above, the coding control table of the partner communication terminal 12 is changed and the changed coding control table of the partner communication terminal 12 is transmitted to the partner communication terminal 12. Sometimes, encoding of application data can be changed in accordance with a change in the header configuration of a wireless communication packet so as to be within an allowable bandwidth in the wireless communication network. This is because, in particular, the parameter (based on the packet header length transmitted / received by the own device (wireless communication device 11) rather than the header length of the packet transmitted / received by the counterpart terminal itself). Since the audio data is encoded based on the encoding control table), it is important in that the counterpart terminal can be encoded according to the environment of the own device.

(Modified example of header configuration of wireless communication packet)
FIG. 15 is a diagram illustrating a header configuration of a communication packet in each communication section when IP mobility is realized by mobile IPv4 (with reburst tunneling). In FIG. 15, the header configuration (header length) of the communication packet in the second wireless communication network is a configuration in which PPPoE is added to the header configuration of the communication packet in the first wireless communication network. In FIG. 15, since the reburst tunneling option is valid (with reburst tunneling), the communication packet from the wireless communication apparatus 11 to the partner communication terminal 12 is transmitted to the partner communication terminal 12 via the HA 23. Similarly, a communication packet from the partner communication terminal 12 to the wireless communication device 11 is also transmitted to the wireless communication device 11 via the HA 23. As in FIG. 6, the uplink / downlink absolute delay time in the first radio communication network is 200/100 msec, and the uplink / downlink absolute delay time in the second radio communication network is 50/50 msec, respectively. And

  FIG. 16 is a diagram showing a header configuration of the communication packet transmitted in FIG. 15, FIG. 16 (a) is a header configuration when passing through the first wireless communication network 15, and FIG. 16 (b) is a second wireless communication. The header structure in the case of passing through the communication network 16 is shown. In FIG. 15, in both the first wireless communication network 15 and the second wireless communication network 16, the header configuration of the upstream packet and the downstream packet in the wireless section is the same. When reburst tunneling is valid, a packet between the wireless communication device 11 and the partner communication terminal 12 is sent once via the HA 23. Therefore, the header length of the packet from the partner communication terminal 12 to the HA 23 is a total of 54 bytes of Ether (14) + IPv4 (20) + UDP (8) + RTP (12), but the packet is encapsulated by the HA 23 (wireless communication). Since the IP address of the device 11 is given), when passing through the first wireless communication network, as shown in FIG. 16 (a), the total becomes 74 bytes including IPv4 (20), and the second wireless In the case of passing through the network 16, as shown in FIG. 16B, a total of 80 bytes including PPPoE (6) is added.

  Also in this case, the telephone function unit 33 generates an encoding control table as shown in the flowchart of FIG. FIG. 17A is a diagram showing a coding rate table (common to uplink and downlink) in the first wireless communication network 15, and FIG. 17B is a diagram of downlink coding rate in the second wireless communication network 15. It is a figure which shows an up-and-down common). 18 (a) is a diagram showing a coding control table for its own device in the first wireless communication network 15, and 18 (b) is a diagram showing a coding control table for its own device in the second wireless communication network 16. is there. In the case of FIG. 15, since the absolute uplink delay time of the first wireless communication network is 200 ms, the accumulable time (Tdlypkc) calculated in step S104 is 20 ms. Therefore, in the coding control table for the own device in the first wireless communication network 15, as shown in FIG. 18A, Quality is 10 to 10 in the 20 ms column of the coding rate table in FIG. Then, 4 entries are registered, and then an entry having a quality of 7-1 is registered in the 40 ms column. Further, since the absolute uplink delay time of the second wireless communication network is 50 ms, the accumulable time (Tdlypkc) calculated in step S104 is 170 ms. Therefore, as shown in FIG. 18B, the 60 ms column of the coding rate table in FIG. 17B is registered as it is in the coding control table for the own apparatus in the second wireless communication network.

  6 and 15, the header configuration of the packet from the counterpart communication terminal 12 to the radio communication device 11 is the same in each of the first radio communication network and the second radio communication network. The counterpart communication coding control tables of the first wireless communication network 15 and the second wireless communication network 16 are shown in FIGS. 14 (a) and 14 (b), respectively, and the first wireless communication network 15 and the second wireless communication network 15 in the case of FIG. This is the same as the counterpart communication control table of the wireless communication network 16.

(Modification example when both own device and partner terminal perform wireless communication)
FIG. 19 is a diagram illustrating an operation flow when both the wireless communication device 11 and the counterpart communication terminal 12 perform wireless communication. In FIG. 19, the counterpart communication terminal 12 has a configuration equivalent to that of the radio communication terminal 11, and the telephone function unit 53, QoS control unit 59, handover control unit 56, and radio information acquisition of the counterpart communication terminal 12 are shown. The units 55 have the same functions as the telephone function unit 33, the QoS control unit 39, the handover control unit 36, and the wireless information acquisition unit 35 of the wireless communication apparatus 11, respectively.

  When both the wireless communication device 11 and the counterpart communication terminal 12 perform radio communication, in principle, both the radio communication device 11 and the counterpart communication terminal 12 have the codes for the own device and the counterpart communication terminal regarding the radio communication network to which each belongs. The communication control table is created, and the created communication control table for the partner communication terminal is sent to the communication partner (partner communication terminal 12 or wireless communication apparatus 11). Therefore, both the wireless communication device 11 and the counterpart communication terminal 12 have two encoding control tables, that is, the own device encoding control table created by itself and the counterpart terminal encoding control table sent from the communication counterpart. Will hold. The wireless communication device 11 and the counterpart communication terminal 12 each use the encoding control table with the shorter packet size of the two encoding control tables so that the narrower radio allowable band is not exceeded. Then, the audio data is encoded.

  When the wireless communication device 11 starts a handover, the wireless communication device 11 creates the partner terminal coding control table, as well as the case shown in FIG. The difference in absolute delay time in the wireless communication network is notified. The counterpart communication terminal 12 adds the difference of the absolute delay time notified from the radio communication device 11 to the absolute delay time in the handover source radio communication network acquired in advance, so that the handover destination of the radio communication device 11 It is possible to create a coding control table for the own terminal for the network.

  When the handover of the wireless communication device 11 is completed, the wireless communication device 11 creates its own device coding control table and notifies the partner communication terminal 12 of the completion of the handover, as in the case shown in FIG. . The partner communication terminal 12 can receive the handover completion notification, obtain the absolute delay time in the handover destination network of the wireless communication device 11, and create the own terminal coding control table according to the absolute delay time. it can.

In addition, this invention is not limited only to the said embodiment, Many deformation | transformation or a change is possible. For example, the present invention is not limited to the case of executing a VoIP application, but can be effectively applied to the case of executing a real-time communication application such as streaming reproduction of multimedia data such as video and music. Also, by setting the reference rate in the coding rate table as, for example, the case where Quality is 5, higher-quality voice communication can be performed. In addition, the wireless communication device creates a control table for the partner terminal on the assumption that the partner terminal uses the same speech encoding algorithm as that of its own device, but the partner terminal uses a speech encoding algorithm different from that of its own device. If it is, the encoding algorithm information corresponding to the encoding algorithm of the counterpart terminal can be created by exchanging the encoding algorithm information in advance. Also, in creating the encoding control table, it is possible to consider the bandwidth of each wireless communication network, jitter, and the like. For example, when jitter (Tjtrtim) is taken into consideration, the accumulable time (Tdlypkc) can be obtained by Equation 4.
[Equation 4]
Tdlypkc ＝ Tdlyprm-Tdlyjtr-Tdlynet-Tdlynec-Tjtrtim

It is a figure which shows schematic structure of the communication network which can use the radio | wireless communication apparatus which concerns on one embodiment of this invention. It is a block diagram which shows schematic structure of the radio | wireless communication apparatus shown in FIG. FIG. 3 is a diagram for explaining an example of an absolute delay time acquisition method by a handover control unit shown in FIG. 2. It is a figure which shows an example of a reference | standard encoding rate table | surface. It is a figure which shows the operation | movement flow of the radio | wireless communication apparatus shown in FIG. It is a figure which shows an example of the header structure of the radio | wireless communication packet in the network shown in FIG. It is a figure which shows the detail of the header structure of the radio | wireless communication packet shown in FIG. It is a figure which shows the detail of the header structure of the radio | wireless communication packet shown in FIG. It is an example of the production | generation flowchart of an encoding control table. It is an example of the production | generation flowchart of an encoding control table. It is a figure which shows an example of an encoding rate table | surface. It is a figure which shows an example of an encoding control table. It is a figure which shows an example of an encoding rate table | surface. It is a figure which shows an example of an encoding control table. It is a figure which shows an example of the header structure of the radio | wireless communication packet in the network shown in FIG. It is a figure which shows the detail of the header structure of the radio | wireless communication packet shown in FIG. It is a figure which shows an example of an encoding rate table | surface. It is a figure which shows an example of an encoding control table. It is a figure which shows the operation | movement flow of a radio | wireless communication apparatus and a partner communication terminal.

Explanation of symbols

11 wireless communication device 12 partner communication terminal 12a handset 15 first wireless communication network 15a access point (base station)
16 Second wireless communication network 16a Base station 17 Packet network 18 Internet 21, 22 SIP server 23 Home agent (HA)
31 First wireless I / F
32 Second wireless I / F
33, 53 Telephone function unit 34 Communication processing unit 35, 55 Wireless information acquisition unit 36, 56 Handover control unit 39, 59 QoS control unit

Claims (2)

A wireless communication unit that performs wireless communication by connecting to a first wireless communication network and a second wireless communication network different from the first wireless communication network;
A calculation unit for calculating a one-way delay time via the second wireless communication network from the own device to a communication partner;
When the header length of the radio section is changed as the handover from the first radio communication network to the second radio communication network is performed, the changed header length and the second calculated by the calculation unit A changing unit that changes a packet transmission interval based on a delay time of the wireless communication network ;
A wireless communication device comprising: The calculation unit calculates a one-way delay time via the second wireless communication network from the communication partner to the own device,
The changing unit includes a delay time of the path該片, the header length is the change, on the basis of the radio communication apparatus according to claim 1, wherein changing the transmission interval of the packet.

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