JP4970066B2 - Wireless communication device, control method thereof, and control method - Google Patents

Description

  The present invention relates to a wireless communication apparatus and a control method thereof.

  Conventionally, a mobile phone is provided with a handover function in order to provide stable call quality while a user carrying the mobile phone is moving. That is, handover refers to a certain base station being connected when a user communicating with a mobile phone moves from a radio zone of a base station to a radio zone of another base station in the same radio communication network. This is a technique for providing a user with stable communication quality by smoothly transitioning from a station to another base station to which it is connected in a short processing time.

  Recently, with the development of wireless communication technology, one wireless communication terminal can be provided with a plurality of wireless communication devices connectable to different wireless communication networks. In a typical configuration, a PDA, a PC, or a mobile phone includes a first wireless communication device that connects to a mobile phone network and a second wireless communication device that connects to a wireless LAN station. However, with regard to the handover technique, although development of a technique in which a terminal moves between base stations in one wireless communication network as in the conventional technique is progressing, it extends over a plurality of different networks when there are a plurality of different wireless communication networks. Development of handover technology based on the environment is delayed.

As a handover to a heterogeneous wireless network, a system using a mobile IP (for example, Non-Patent Document 1) as shown in FIG. 6 has been proposed. The basic operation of Mobile IP is as follows. Basically, it is a method of switching the upper and lower lines simultaneously.
(I) Scan the physical means connected to the destination LAN1 or LAN2 (in the case of a wireless LAN, scan valid radio waves).
(Ii) When the wireless communication terminal (MN; mobile node) 3 enters the destination LAN 1 or LAN 2, a registration request is transmitted to the home agent 6 via the external agents 4 and 5. The home agent (HA) 6 that has received this transmits an agent advertisement (data including IP address information) to the MN 3. This completes location registration.
(Iii) Since the communication partner 7 appears to have the MN 3 on the home LAN 8, the data sent by the communication partner 7 is transmitted to the home agent 6.
(Iv) The home agent 6 uses the location registration information, wraps (encapsulates) the received data with a care-of IP address, and transfers it to any one of the external agents 4 or 5. Encapsulation uses a protocol defined specifically for Mobile IP.
(V) The external agent 4 or 5 extracts the data by releasing the capsule, and transfers the extracted data to the MN 3.
(Vi) The MN 3 transmits data to the communication partner 7 through the Internet 9.
In addition, handover between the same wireless communication networks is performed by a method of unconditionally switching up and down lines simultaneously.
C. Perkins, “IP Mobility Support (RFC2002)”, [online], October 1996, IETF, [March 15, 2006 search], Internet <URL: http: //www.ietf.org / rfc /rfc2002.txt

  The above-described mobile IP according to the prior art is a technology that enables continuous communication with the same IP address even if a terminal moves between networks in an environment where a plurality of networks are interconnected. In both the home wireless / wired LAN and the outdoor commercial wireless LAN, communication is possible with the same IP address. The handover technique in this case is a technique of moving using one wireless communication device, and is a method of switching the upper and lower lines simultaneously to another wireless communication network of the same type.

As described above, only the method of switching the upper and lower lines simultaneously to another wireless communication network has the following problems.
・ Depending on the application, the latency (delay time) required for switching may cause a significant deterioration in quality (bandwidth reduction, temporary stop of communication, etc.).
-A handover method that takes into account policies for selecting a wireless communication network (service quality priority, communication charge priority, call duration (battery life / continuous use time, etc.)) could not be selected.
・ The area of the wireless communication network was small due to the imbalance between the link budgets of the upper and lower lines. That is, the narrower area between the upper and lower areas is a practically communicable zone, and either the area that reaches the upper side or the area that reaches the lower side is wasted and cannot be used effectively.
Although the handover between the same wireless communication networks generates a considerably large latency, the handover is performed regardless of the application, and as a result, the service quality may be significantly deteriorated.

  Furthermore, recently, with the development of wireless communication technology, one wireless communication terminal can be provided with a plurality of wireless communication devices (communication cards) that can be connected to different wireless communication networks. A typical configuration is that a PDA, PC, or mobile phone is connected to a first wireless communication device that connects to a base station of a mobile phone network and a wireless LAN station (base station such as home wireless LAN, WiFi, or WiMAX). And a second wireless communication device. However, development of a handover technique in which a terminal moves between base stations in a single wireless communication network using one wireless communication device is in progress. On the other hand, there are a plurality of different types of wireless communication networks, and further, there is a demand for the development of a handover technique between systems on the premise of an environment extending over a plurality of different types of networks.

  In addition, a so-called multi-mode terminal that can be connected to a plurality of wireless communication networks can be connected to a plurality of wireless communication networks, but the available bandwidth, communication fee, and continuous call time (battery life) are connected to each other. It depends on. Also, the allowable delay time that can be accepted and the necessary bandwidth differ depending on the application used by the user. Therefore, it is not appropriate to simply hand over to a wireless network with a large bandwidth or to hand over to another wireless communication network at the same time using only the deterioration of the communication state at the terminal as a trigger. Therefore, there is a need for a handover technique that considers various network environments.

  Therefore, an object of the present invention is a technique (wireless communication apparatus and control method thereof) capable of realizing an advanced handover in which an optimum one is selected from a plurality of types of handover methods in a wireless communication apparatus connectable to a plurality of wireless networks. Is to provide.

In order to solve the above-described problems, a wireless communication device according to a first invention
A wireless communication device connectable to a plurality of wireless communication networks,
An uplink / downlink synchronization method for handing over an uplink and a downlink at the same time, and an uplink / downlink asynchronous method for handing over an uplink and a downlink asynchronously (independently) (Including the case of handing over to a base station / sector) and simultaneously handing over to the other wireless communication network while performing connection with the other wireless communication network while maintaining the connection with the connected wireless communication network and performing band complementation Of the connection bandwidth supplementation method and the same network switching method for handover from a connected base station or sector to another base station or sector in the same wireless communication network, the communication quality in the connected wireless communication network is improved. Based on the simultaneous connection bandwidth supplement scheme, or the other three A handover method selector for selecting any one handover method of the formula,
A handover control unit that controls to perform handover using the handover method selected by the handover method selection unit;
It is characterized by comprising.

A wireless communication apparatus according to the second invention is
An operation input unit for inputting and updating a policy (selection criteria);
A policy storage unit that stores a policy (selection criterion) related to handover input by the operation input unit;
The handover method selector, based on the policy stored in the policy storage unit, the selection of Ha Ndooba scheme,
It is characterized by that.

According to a third aspect of the present invention, there is provided a wireless communication device.
An operation input unit for setting (input, update, selection, etc.) the policy is further provided.

A wireless communication device according to a fourth aspect of the invention is
From the application that performs wireless communication, the allowable delay time, the required bandwidth of the uplink,
And an application information acquisition unit that acquires at least one application information of the required bandwidth of the downlink,
The handover method selector, based on the application information acquired by the application information acquiring unit, the selection of Ha Ndooba scheme,
It is characterized by that.

According to a fifth aspect of the present invention, there is provided a wireless communication apparatus.
Latency (delay time) required for handover within each wireless communication network (that is, between base stations / sectors of the same wireless communication network) of the plurality of wireless communication networks, and delay tolerance specified for each communication application A latency storage for storing time, and
The handover method selection unit further comprises a time comparison unit that compares the latency stored in the latency storage unit with the allowable delay time of the application during communication,
The handover method selector, based on a comparison result by said time comparing unit (for example, if the latency exceeds a allowable delay time), the selection of Ha Ndooba method, it is characterized.

A wireless communication device according to a sixth invention
A delay time measurement unit for measuring an average delay time of a wireless communication network during communication;
A handover destination delay time acquisition unit that acquires an average delay time of another wireless communication network of a handover destination candidate (by measuring or by reading from a storage unit that stores a result measured in advance);
A time difference calculating unit that calculates a time difference between an average delay time measured by the delay time measuring unit and an average delay time of the handover destination delay time;
A time interval as a result of adding the larger average delay time of the average delay time of the wireless communication network in communication or the average delay time of another wireless communication network of the handover destination candidate to the time difference calculated by the time difference calculation unit And a comparison unit for comparing the allowable delay time of the application,
The handover method selection unit is
In accordance with the comparison result by the comparison unit, it is determined whether to select the simultaneous connection bandwidth complementing method or any one of the other three methods.
It is characterized by that.

According to a seventh aspect of the present invention, there is provided a wireless communication apparatus.
A communication quality monitoring unit for monitoring the communication quality of the uplink and downlink of the wireless network in communication;
A communication area monitoring unit (including sector and area boundaries between the same wireless communication networks) for monitoring whether the wireless communication network is within an area of another wireless communication network;
The handover method selector is also based on the communication quality unit and communication monitoring unit of the monitoring results, the selection of Ha Ndooba scheme,
It is characterized by that.

A wireless communication device according to an eighth aspect of the invention is
A current value calculation unit that calculates a current value (at least a transmission current value) consumed by communication of each wireless communication network for each wireless communication network;
The handover method selector is also based on the current value calculated by the current value calculator, the selection of Ha Ndooba method, characterized in that.

According to a ninth aspect of the present invention, there is provided a wireless communication apparatus
The current value calculator is
Based on at least the transmission output and the transmission bandwidth (for example, the number of subcarriers in a multicarrier communication scheme such as OFDMA), a current value consumed during transmission is calculated.
It is characterized by that.

  As described above, the solution of the present invention has been described as an apparatus. However, the present invention can be realized as a method, a program, and a storage medium storing the program, which are substantially equivalent thereto, and the scope of the present invention. It should be understood that these are also included.

For example, a control method for a wireless communication apparatus according to a tenth aspect of the present invention realized as a method is a control method for a wireless communication apparatus connectable to a plurality of wireless communication networks,
An uplink / downlink synchronization method in which an uplink and a downlink are handed over simultaneously using an arithmetic means (a processor such as a CPU or DSP), and an uplink / downlink asynchronous method in which an uplink and a downlink are handed over asynchronously (independently) In a wireless communication network, including the case where one of the upper and lower lines is handed over to another base station / sector), the band is connected with the other wireless communication network while maintaining the connection with the connected wireless communication network. Simultaneous connection bandwidth complementing method for handing over to another wireless communication network while performing complementation, and switching method within the same network for handing over from a connected base station or sector to another base station or sector in the same wireless communication network of, on the basis of the communication quality in a wireless communication network in the connection, before A handover method selection step of selecting either one handover method of concurrent bands complement system or other three methods,
A handover control step for controlling to perform handover using the handover method selected in the handover method selection step;
It is characterized by including.

  According to the present invention, in a network environment that can be connected to a plurality of networks, it is possible to perform handover by automatically selecting an optimum method from a plurality of types of handover methods according to the situation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Embodiments of a wireless communication terminal and a control method thereof according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a system in which a wireless communication terminal according to the present invention is used. In the system shown in FIG. 1, by establishing a tunnel by VPN: Virtual Private Network (IPSec) 13, 14, 15 between the wireless communication terminal (MN) 11 and the switching server (SS) 12, L3 (Layer 3 ) Virtualization to establish IP mobility. Thus, unlike mobile IP, communication can be performed between the MN 11 and the SS 12 using a plurality of wireless communication networks at the same time. That is, it is possible to communicate with different wireless communication networks in the upper and lower wireless links.

  In FIG. 1, the MN 11 has means for detecting communication quality deterioration of the downlink radio link and means for detecting silence in the uplink voice, and the SS 12 is means for detecting communication quality deterioration of the uplink radio link. And means for detecting silence in the downstream voice. As a result, when the communication quality degradation of the downlink radio link is detected by the MN 11, after the silence of the downlink voice is detected by the SS 12, the communication path of the downlink radio link is switched to another different communication path, and then the uplink of the MN 11 By switching the communication path of the uplink wireless link after detecting the silence of the voice, it is possible to prevent deterioration in communication quality such as sound interruption and instantaneous interruption accompanying switching of the communication path.

  On the other hand, when the deterioration of the communication quality of the uplink radio link is detected in SS12, the silence path of the uplink voice is detected in MN11, and then the communication path of the uplink radio link is switched to another different communication path, and then SS12 By switching the communication path of the downlink radio link after detecting the silence of the downlink voice in, it is possible to prevent deterioration in communication quality such as sound interruption or instantaneous interruption due to switching of the communication path.

  In addition, after switching the communication path by switching the top and bottom independently to the codec optimal for the characteristics (bandwidth, delay, jitter, etc.) of the uplink / downlink radio link when switching the communication path when there is no sound as described above Communication quality can be improved and noise during codec switching can be prevented.

  When the MN 11 has a plurality of wireless communication means, it is not preferable from the viewpoint of battery saving of the MN 11 to maintain all communication paths in the communication state. Therefore, in the case where the deterioration of the communication quality already described is detected by the MN 11 and the SS 12, Each communication path with a different switching destination candidate has a two-stage threshold. As a result, after the SS12 shifts the communication means different in MN11 from the dormant or power-off state to the communication state with the first threshold value, the MN11 and SS12 communicate with the specified control message, respectively. It is possible to check the communication state of the route and determine the communication route to be switched to.

  Thereafter, when the communication quality degradation threshold at the MN 11 or the SS 12 reaches the second threshold, the communication quality is improved while switching to another communication path that has already been determined, while realizing battery saving of the MN 11. Switching to another communication path (handover) can be realized without deterioration.

The wireless communication apparatus (control method) according to the present invention performs handover by automatically selecting the optimum method according to the situation from the following four handover methods.
-Uplink / downlink synchronization method : Handover of uplink and downlink at the same time.
Asynchronous uplink / downlink method : Handover is performed asynchronously (independently) between the uplink and downlink.
-Simultaneous connection bandwidth complementing method : Handing over to another wireless communication network while supplementing bandwidth by connecting simultaneously with another wireless communication network while maintaining connection with the currently connected wireless communication network.
Intra-network switching method : Handover from a connected base station or sector to another base station or sector within the same wireless communication network.

  For example, in the case of handover using the uplink / downlink asynchronous method, when the quality of one of the upper and lower lines deteriorates, only the deteriorated line is switched to another wireless communication network or another base station. Is shorter than the uplink / downlink synchronization method, which is very advantageous from the viewpoint of communication quality.

  In addition, the simultaneous connection bandwidth complement method is a method of supplementing the bandwidth that is not available in the wireless communication network that is the main route currently being communicated by simultaneously communicating with other wireless communication networks, and moves to the area fringe of the main route. As a result, the rate of communication in other wireless communication networks increases, and when the main route goes out of the area, communication is performed in another wireless communication network 100% (that is, handover is completed). If the delay of the wireless network is ignored, the latency required for handover is theoretically zero, which is extremely advantageous from the viewpoint of communication quality. However, since a plurality of wireless communication networks are used at the same time, the simultaneous connection band supplement method and the uplink / downlink asynchronous method are disadvantageous compared to the uplink / downlink synchronization method from the viewpoint of communication charge, call time, and power consumption.

  In addition, in a wireless communication network in which a large latency that cannot be ignored by a handover between the same wireless communication networks occurs, service quality may be significantly degraded as a result of unconditionally performing handover. For example, it is possible to maintain good service quality by performing handover to another wireless network in consideration of the allowable delay time and policy of the application. In this way, by installing a means for defining / acquiring or notifying a handover policy, an allowable delay time of an application, and a latency of a handover between the same wireless networks, an optimal handover for a user-selected policy and application can be performed. realizable.

  Hereinafter, for convenience, the uplink / downlink synchronization method is referred to as basic handover, the uplink / downlink asynchronous method is referred to as independent top / bottom handover, the simultaneous connection band supplement method is referred to as band supplement, and the same intra-network switching method is referred to as inter-network handover. Further, it is assumed that the latency at the application level by basic handover is Lbh [ms]. Assume that the latency at the application level between the same networks is Lsnw [ms].

A typical delay time (up and down) of each wireless communication network is defined as follows.
DNW1: Typical delay time of the wireless communication network NW1
DNW2: Typical delay time of the wireless communication network NW2
DNW3: Typical delay time of the wireless communication network NW3

In addition, since the delay can always be monitored in the currently communicating wireless communication network, the average delay time in the most recent T seconds is defined as Dcrt. In the handover destination wireless network, an actual delay can be measured by transmitting an Echo command from the MN to the SS after establishing communication. Here, the average delay time measured over T2 seconds is set as follows for each wireless communication network.
DmNW1: Average delay time measured when the handover destination is the wireless communication network NW1 (round trip)
DmNW2: Average delay time measured when the handover destination is the wireless communication network NW2 (round trip)
DmNW3: Average delay time measured when the handover destination is the wireless communication network NW3 (round trip)

  2 is a block diagram of a wireless communication terminal (MN; mobile node) according to an embodiment of the present invention, FIG. 3A is a frame format of a data packet on the MN side, and FIG. 3B is access control on the MN side. Packet frame format. In FIG. 2, a wireless communication terminal (MN) 11 includes care-of IP address interface units 121, 122, and 123 to which communication cards 111, 112, and 113 are connected, an access control unit 130, an operation input unit 140, and a storage unit 142. , Control unit 150, application 160, and virtual IP address 161. In addition, the MN 11 includes a communication path selection logic unit (handover method selection unit) 170, each mobile communication delay time measurement unit 180, and a band distribution transmission processing unit 190.

  In FIG. 3, the frame format transmitted from the wireless communication terminal MN is described, but the switching server SS can know through which communication path it is transmitted by looking at the care-of IP address. In addition, after decapsulating the VPN in the switching server, the home IP address in Fig. 3 (this is actually a virtual IP address that is uniquely used by the MN application) is used as the source address of the correspondent CN (Correspondence Node). IP mobility is ensured by setting the address to the destination address and sending the payload to the CN. Therefore, in principle, the switching server SS can transmit using a plurality of communication paths with the MN. In addition, the MN can receive a packet transmitted by the switching server through a communication path different from the communication path transmitted by itself. Basically, the MN 11 only needs to send (input) a packet received from the switching server to the application based on the home IP address uniquely used by the MN application in the packet from which the VPN encapsulation is removed. It does not matter which communication path is used by the switching server. In other words, a packet transmitted from the switching server via any communication path can be sent to the application of the MN. Therefore, for packets received from any communication path by both the MN and the switching server, after the VPN encapsulation is removed, packets received from multiple communication paths become frames of the same format. As long as consistency is ensured, communication can be maintained through different communication paths for uplink and downlink.

  Returning to the description of FIG. 2, the access control unit 130 switches the communication interface and controls the echo back of the control packet between the MN 11 and the SS 12 separately from the normal data communication between the MN 11 and the SS 12. Do. The access control unit 130 includes a communication area monitoring unit (not shown), and the communication area monitoring unit checks the communication environment by performing echo back on a communication path that is not currently communicating. The communication area monitoring unit is used to check the communication state by monitoring the reception packet interval at each of the MN 11 and the SS 12, and to determine which communication path to switch to in the communication path selection logic unit 170.

  The control unit 150 includes a received packet consistency processing unit 151, a wireless information analysis processing unit 152, a received packet analysis processing unit 153, a delay time analysis processing unit 154, a policy analysis processing unit 155, an allowable delay time / necessary bandwidth analysis unit 156, A bandwidth ratio calculation processing unit 157 and a handover control unit 158 are included.

  The received packet consistency processing unit 151 realizes the function of a jitter buffer and performs order matching of packets received from two or more mobile communication networks. In the case of a real-time application such as VoIP (Voice Over IP), the sequence number of RTP (Real-time transport protocol) is checked.

  The radio information analysis processing unit 152 analyzes radio information (for example, throughput, SINR, RSSI, DRC, Tx_Power) received by the MN 11 in mobile communication during communication, and detects deterioration in communication quality in the downlink radio link Used to do. The received packet analysis processing unit 153 analyzes statistical information (throughput, packet loss, underrun count, overrun count) of the data packet received by the MN 11, and determines communication quality deterioration if the communication path is in communication. In the communication path that is not in communication, while checking the communication state (radio wave propagation environment), it is determined whether or not the communication path should be switched, and the determination result is sent to the communication path selection logic unit (handover method) Selection section) 170.

  The operation input unit 140 functions as a policy setting unit, and is a user interface through which a user sets (or inputs / selects) a policy regarding handover. The storage unit 142 stores set information and the like. The policy analysis processing unit 155 is a processing unit that analyzes a policy related to handover input by a user. Each mobile communication delay time measurement unit 180 is a processing unit that measures a delay time for each wireless communication network. The delay time analysis processing unit 154 of each radio communication network uses two different radios using the predefined average delay time of each radio communication network and the delay time measured by each mobile communication delay time measurement unit 180. It is a processing unit that calculates a delay difference (time difference) between communication networks. The allowable delay time / required bandwidth analysis unit 156 is a processing unit that analyzes the allowable delay time and the required bandwidth notified by the application.

  The bandwidth ratio calculation processing unit 157 is a processing unit that calculates a bandwidth ratio when the SS performs distributed transmission in a plurality of wireless communication networks based on the number of received packets. The band distribution transmission processing unit 190 performs distribution transmission using a plurality of different wireless communication networks based on the band ratio notified from the SS.

  The MN 11 further includes an upstream voice silence detection unit (not shown), and the silence detection unit detects that the upstream voice is silent before encoding the VoIP RTP packet. As a result, the upstream communication path can be switched during silence. The communication path selection logic unit 170 determines whether or not to switch the communication path to another communication path and determines which communication path to switch to when switching.

  By using the virtual IP address 161 (home IP address) for the application 160 of the MN 11, by always providing the same IP address to the application 160 even if the mobile communication network to which the MN 11 is connected changes, IP mobility is secured. For different mobile communications, each has a care-of IP address CoA (in many cases, given from the mobile network when the MN 11 connects to the mobile communication network).

  In SS12, it is possible to know which communication path is used for transmission by referring to the care-of IP address. In SS12, after decapsulating the VPN capsules 13, 14, and 15, the home IP address of the data packet shown in FIG. 3 (this is actually a virtual IP address uniquely used by the application 160 of the MN11). IP mobility is ensured by setting the address of the communication partner CN (Correspondence Node) as a destination address and transmitting a payload to the CN. Accordingly, the SS 12 can transmit with the MN 11 using a plurality of communication paths.

  Further, the MN 11 can receive the packet transmitted by the SS 12 via a communication path different from the communication path transmitted by the MN 11. The MN 11 only has to send (input) the packet received from the SS 12 to the home IP address uniquely used by the application 160 of the MN 11 in the packet from which the VPN encapsulation is removed. It does not matter which communication path is used by the SS 12 for transmission. In other words, regardless of the communication path used by the SS 12 to transmit a packet, the packet can be transmitted (input) to the application 160 of the MN 11.

  Therefore, both the MN11 and SS12 receive packets because packets received from multiple communication paths become frames of the same format after removing the VPN encapsulation for packets received from any communication path. As long as packet consistency is ensured, communication can be maintained on different communication paths for uplink and downlink.

The control unit 150 further includes an application information acquisition unit (not shown), and the application information acquisition unit acquires the allowable delay (Dap), the required upstream bandwidth (BW_UPap), and the required downstream bandwidth (BW_DNap) from the application 160. To do. Received packet analysis processing section 153 predicts the average uplink and downlink bandwidth from radio information (RSSI, CNR, SNR, DRC, etc.) of the handover destination radio network. The predicted average bandwidth is as follows.
BW_UPexNW1: Expected average bandwidth of uplink in the wireless communication network NW1
BW_UPexNW2: Expected average bandwidth of uplink in the wireless communication network NW2
BW_UPexNW3: Expected average bandwidth of uplink in the wireless communication network NW3
BW_DNexNW1: Average downlink bandwidth in wireless communication network NW1
BW_DNexNW2: Predicted average bandwidth of downlink in the wireless communication network NW2
BW_DNexNW3: Downstream predicted average bandwidth in the wireless communication network NW3 For example, in the case of CDMA2000 1xEV-DO as the wireless communication network, calculation is performed as follows.

<Upstream expected average bandwidth>
The maximum transmission rate converted from the average RSSI (Received Signal Strength Indicator) monitored at the T3 [ms] period for the past T2 seconds is collected, and the predicted average bandwidth of the uplink is calculated from those averages.
<Downstream predicted average bandwidth>
From the average DRC (Data Rate Control) monitored at the period of T3 [ms], the average DRC for the past T2 seconds is calculated. The downlink average bandwidth is calculated from the DRC.

<Transmission current value of wireless communication network device>
Since it is the current at the time of transmission of each wireless communication device that mainly affects the total communication time until charging is required, that is, the current consumption value, the current at the time of transmission is as follows for each wireless communication device: (Current values I_NW1, I_NW2, and I_NW3 of the wireless communication networks NW1, NW2, and NW3). For example, the current value I_NW1 of the wireless communication network NW1 is obtained as follows.

(i) When the wireless communication is not multi-carrier communication (transmission bandwidth is constant) (for example, CDMA2000 1xEV-DO), the current during transmission can be obtained from the transmission output power value of the terminal (Tx_pwr), Since the current value consumed in reception can be ignored, this can be regarded as the current value consumed in the communication. The calculation method differs depending on the communication method, but here,
Current value during transmission = f (Tx_pwr)
It is defined as If it cannot be expressed as a function, the current value at the time of transmission corresponding to each 0.5 dBm may be defined as a table. Therefore, for example, the current value at the time of transmission of the wireless communication network NW1 is obtained by the following equation.
I_NW1 = f (Tx_pwr)

(ii) When the wireless communication is multicarrier communication (transmission bandwidth is variable), for example, in the case of multicarrier communication such as OFDMA, the current value at the time of transmission is the transmission output power value (Tx_pwr) ) And transmission bandwidth (subcarrier bandwidth). If the transmission bandwidth is BW_Tx,
Current during transmission = F (Tx_pwr, BW_Tx)
It is defined as Therefore, for example, the current value at the time of transmission of the wireless communication network NW1 is obtained by the following equation.
I_NW1 = F (Tx_pwr, BW_Tx)

<Transmission current during handover>
Regarding basic handover and independent vertical handover, since there are factors that affect current values such as transmission output power value and transmission bandwidth, it is generally not possible to determine that basic handover has a smaller transmission current. Therefore, the transmission current value is calculated as follows.

(1) When handing over from the wireless communication network NW1 to the wireless communication network NW2・ Transmission current at the time of basic handover (I_bho) = I_NW2
-When downlink transmission is transmitted by the wireless communication network NW2 in vertical independent handover Transmission current (I_iho) = I_NW1 during vertical independent handover
-When uplink transmission is transmitted by the wireless communication network NW2 by vertical independent handover Transmission current (I_iho) = I_NW2 at the vertical independent handover

(2) When handing over from the wireless communication network NW2 to the wireless communication network NW1- Transmission current at the time of basic handover (I_bho) = I_NW1
-When downlink transmission is transmitted by the wireless communication network NW1 in vertical independent handover Transmission current (I_iho) = I_NW2 during vertical independent handover
-When uplink transmission is transmitted by the wireless communication network NW1 by the vertical independent handover Transmission current (I_iho) = I_NW1 at the vertical independent handover

<Maximum jitter buffer amount during handover with bandwidth supplement method>
Since communication is performed simultaneously on two wireless communication networks, the maximum jitter buffer when executing a real-time application is obtained by adding the delay difference to the delay time of the wireless communication network having a large delay. For example, the delay times of the wireless communication network NW1 and the wireless communication network NW2 are DNW1 and DNW2, respectively, according to the above-described definitions, so the required maximum jitter buffer amount is Max (DmNW1, DmNW2) + | DmNW1-DmNW2 | . When the average delay time of the handover destination wireless communication network NW2 cannot be measured, DNW2 is used instead of DmNW2. That is, the required maximum jitter buffer amount is Max (DmNW1, DNW2) + | DmNW1-DNW2 |.

FIG. 4 is a functional block diagram of the switching server (SS12). In this functional block, the following processing is performed.
(1) MN Transmission / Reception Processing Since the data packet transmitted from the MN 11 is configured in the IPSec tunnel mode format as shown in FIG. 3A, a socket is created in the data program format, and transmission / reception to / from the MN 11 is performed. Since the access control packet is controlled by the TCP protocol, transmission / reception processing to / from the MN 11 is performed in the format shown in FIG. 3B.

(2) Home packet source IP address check The home IP address of the data packet transmitted from the MN 11 is compared with the home IP address registered in the SS 12. The home IP address is the virtual IP address 161 of the MN 11, and is notified from the MN 11 to the SS 12 in the initial initial procedure between the MN 11 and the SS 12.

(3) Receive packet consistency processing and reception processing Jitter buffer functions and match the order of packets received from two or more mobile communication networks. In the case of a real-time application such as VoIP, the RTP sequence number is checked.

(4) Receive packet statistical processing and reception processing data packet statistical information (packet loss, throughput, underrun count, overrun count, and packet arrival interval) are acquired, and deterioration of uplink communication quality is detected.

(5) Control of the entire process SS12 of the control unit is performed.

(6) Access control processing The access control packet transmitted from the MN 11 is processed based on the control code. Table 1 shows access control packets from MN11 to SS11, and Table 2 shows access control packets from SS12 to MN11. The control code is the first byte of the payload part. The home IP address is included in 4 bytes after the access control code. When the access control packet is transmitted to SS12, SS12 transmits a response packet to MN11 after the control processing.

(7) Rewrite the MN carrier IP address associated with the home IP address registered in the interface switching SS12.

(8) Response packet creation Creates a response packet for access control. The response packet is composed of a copy of the control code and access control packet payload portion of Table 2.

(9) CN transmission processing The home packet sent from the MN 11 is sent to the CN. Since the home packet is composed of IP packets, the socket is created at the IP layer.

(10) Downstream silence detection is performed by statistically processing the arrival interval of received packets from the downstream silence detector CN.

(11) The home packet sent from the packet reconfiguration CN is used as a payload when transmitting to the MN 11.

(12) Destination IP address check of home packet The destination IP address of the home packet sent from CN is compared with the home IP address registered in SS12. As a result, it is determined which MN 11 carrier IP address the home packet belongs to.

(13) Protocol Check The Ethernet (registered trademark) driver (eth1) on the CN side receives the packet at the data link layer. Among the packets received here, the only packets that need to be received by the SS 12 are the IP packet whose destination is the home IP address and the ARP (Address Resolution Protocol). The protocol is determined by querying the protocol type in the data link layer header of the received packet.

(14) The packet capture SS 12 can receive all data packets by binding the socket to the MAC address of the data link layer. As a result, data including the data link layer header is received.

(15) ARP response packet creation SS12 responds to ARP requests for all registered home IP addresses using the MAC address of SS12. Thereby, all the home packets whose destination from the CN is the home IP address can be received by the SS 12.

(16) Communication path selection unit (6) Access so that the communication status of other communication paths is checked by echoing back a control message with MN 11 after the upstream communication quality during communication is deteriorated. The control unit is controlled, and the downlink communication path to be switched next is determined based on the check result.

(17) The transmission packet is distributed to the communication path selected by the transmission packet distribution unit SS12. Since the VPNs 13, 14, and 15 have different tunnel formats (in particular, IP addresses) for each communication, a frame for the selected communication path is configured. In addition, when performing band complementation, distributed transmission is performed in a plurality of different wireless communication networks based on the band ratio notified from the MN.

<Handover method selection algorithm>
FIG. 5 is a flowchart illustrating an example of a handover selection algorithm used in the wireless communication terminal according to the present invention. First, it is assumed that the wireless communication terminal is communicating on the communication network NW1. In step S11, the radio communication terminal MN monitors the communication quality of the upper and lower lines at a constant cycle. For downlink, using PER (packet error), CINR, RSSI, etc., it is determined that the communication quality has deteriorated when a certain threshold condition is satisfied. As for uplink, when the PER, delay, jitter, etc. of the IP packet fluctuate in the Switching Server (SS) and a certain threshold condition is not satisfied, the wireless communication terminal is notified that the communication quality has deteriorated. In step S12, it is determined whether the upper or lower communication quality has deteriorated. If it has deteriorated, step S13 is executed, and if it has not deteriorated, the process returns to step S11.

  In step S13, it is determined whether another wireless communication network NW2 is available. If it can be used, step S14 is executed, and if it cannot be used, the process returns to step S11. In step S14, it is determined whether a handover condition between the same wireless networks is established. If it is established, the process proceeds to step S15. If not, step S16 is executed. In step S15, it is determined whether or not the latency (Lsnw: preset value) at the application level of the same wireless network handover is equal to or less than the allowable delay (Dap) of the application being executed. If the determination condition is satisfied, handover between the same wireless networks is executed. If the determination condition is not satisfied, step S17 is executed.

  In step S16, it is determined whether or not the call quality is the first priority among the preset policies. If the determination condition is satisfied, step S17 is executed. If the determination condition is not satisfied, the process proceeds to step S24. In step S17, it is determined whether or not the quality of the uplink line of the upper and lower lines has deteriorated. If the uplink quality is degraded, step S18 is executed. If the downlink quality is degraded, step S21 is executed. In step S18, it is determined whether or not the estimated uplink average bandwidth (BW_UPexNW2) of the wireless communication network NW2 is equal to or greater than the necessary bandwidth (BW_UPap) for the application being executed. If the bandwidth exceeds the required bandwidth, the top and bottom independent handover is selected, and the process is terminated. If it is smaller than the required bandwidth, step S19 is executed.

  In step S19, it is determined whether or not the maximum delay when band complementation is performed in the wireless communication network NW2 and the wireless communication network NW1 is equal to or less than the allowable delay (Dap) of the application being executed. If it is equal to or shorter than the allowable delay, the band supplement type handover is executed. If it is larger than the allowable delay, step S20 is executed. In step S20, it is determined whether or not the predicted average bandwidth (BW_UPexNW2) of the uplink line in the wireless communication network NW2 is 1 / N or more of the required uplink bandwidth (BW_UPap) of the application. If the determination condition is satisfied, the top and bottom independent handover is selected, and the process ends. If the determination condition is not satisfied, the bandwidth complementing type handover is selected and the process ends.

  In step S21, it is determined whether or not the predicted downlink average bandwidth (BW_DNexNW2) of the wireless communication network NW2 is equal to or greater than the necessary bandwidth (BW_DNap) of the application being executed. If the downlink average predicted bandwidth is greater than or equal to the required bandwidth, the top and bottom independent handovers are selected and the process ends. When the predicted downlink average bandwidth is smaller than the required bandwidth, the process proceeds to step S22. In step S22, it is determined whether or not the maximum delay when band complementation is performed in the wireless communication network NW2 and the wireless communication network NW1 is equal to or less than the allowable delay (Dap) of the application being executed. If it is equal to or shorter than the allowable delay, the band supplement type handover is executed. If larger than the allowable delay, the process proceeds to step S23. In step S23, it is determined whether the predicted average bandwidth (BW_DNexNW2) of the downlink in the wireless communication network NW2 is 1 / N or more of the required downlink bandwidth (BW_DNap) of the application. If the determination condition is satisfied, the top and bottom independent handover is selected, and the process ends. If the determination condition is not satisfied, the bandwidth complementing type handover is selected and the process ends.

  In step S24, it is determined whether or not the call time has the first priority in the preset policy. If the determination condition is satisfied, the process proceeds to step S25. If the determination condition is not satisfied, the basic handover is selected and the process is terminated. In step S25, it is determined whether or not the quality of the uplink line of the upper and lower lines has deteriorated. If the uplink quality is degraded, step S26 is executed. If the downlink quality is degraded, the process proceeds to step S27. In step S26, a transmission current value (I_bho) when basic handover is performed is calculated. A transmission current value (I_Iho) in the case of performing independent handover is calculated, and then Step S28 is executed.

  In step S27, it is determined whether or not the call quality is preset and is the second priority in the Policy. If the determination condition is satisfied, the top and bottom independent handover is selected, and the process ends. If the determination condition is not satisfied, the basic handover is selected and the process is terminated. In step S28, it is determined whether or not the transmission current value (I_bho) when the basic handover is performed is smaller than the transmission current value (I_Iho) when the vertical independent handover is performed. If the determination condition is satisfied, the basic handover is selected and the process is terminated. If the determination condition is not satisfied, the top and bottom independent handover is selected and the process is terminated.

  The wireless communication terminal (MN) can set in advance as network selection policy / preference information whether call quality priority, call (communication) time priority (battery saving priority), or call (communication) charge priority. In other words, the wireless communication terminal (MN) is a so-called policy / preference (selection criterion) that says whether priority is given to realizing the optimum bandwidth for the application on the receiving side or priority is given to the lowest charge. ) Has a user interface that can be selected. The user interface (operation input unit) can be selected with a software key on the display, or can be selected with a hardware key in advance.

The four handover methods are referred to as methods (1) to (4), and which handover method is preferentially selected in a specific network configuration will be described.
Method (1): Uplink / downlink synchronization method Method (2): Uplink / downlink asynchronous method Method (3): Simultaneous connection bandwidth supplement method Method (4): Switching method within the same network

  As shown in Table 4, when “call quality priority” is set as policy information and “WiMAX” is used as the network, the priority of methods (2), (3), and (1) A handover method is selected in order. That is, the wireless communication terminal according to the present invention first determines whether or not the handover method of the method (2) with the highest priority can be executed, and selects the method (2) if possible. If not possible, it is sequentially determined whether or not a lower priority method can be executed, and a method determined to be possible is selected. Note that WiMAX is not included in the selection candidates when priority is given to call quality because loud sound interruption or the like occurs during handover within the same network.

  As shown in Table 5, when “call quality priority” is set as policy information and “EVDO” is used as the network, methods (4), (2), (3), ( The handover method is selected with the priority of 1). That is, the radio communication terminal according to the present invention first determines whether or not the handover method of the scheme (4) with the highest priority is feasible, and performs handover with the scheme (4) if possible. If not possible, it is sequentially determined whether or not a lower priority method can be executed, and a method determined to be possible is selected.

  As shown in Table 6, when “call time priority” is set as policy information and “WiMAX” is used as the network, the handover method is selected in the priority order shown in the table.

  As shown in Table 7, when “call time priority” is set as policy information and EVDO is used as the network, the handover method is selected in the priority order shown in the table.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, functions included in each member, each means, each step, etc. can be rearranged so as not to be logically contradictory, and a plurality of means, steps, etc. can be combined or divided into one. Is possible. In the embodiment, a mode in which three communication cards that support each of the three wireless communication networks are used has been described. However, the wireless communication apparatus according to the present invention is not limited to this embodiment, and a plurality of wireless communication networks are provided. It may be a wireless communication device supported by one communication card or a wireless communication device incorporating a function of communicating with a plurality of wireless communication networks. Further, FIG. 5 is based on the condition that another wireless communication network can be used. However, if another wireless communication network cannot be used, the handover (basic handover) by the same wireless communication network is of course selected. It is.

It is a block diagram of a system in which a wireless communication terminal according to the present invention is used. 1 is a block diagram of a wireless communication terminal (MN; mobile node) according to an embodiment of the present invention. It is a figure which shows a frame format. It is a functional block diagram of a switching server (SS12). 6 is a flowchart illustrating an example of a handover selection algorithm used in a wireless communication terminal according to the present invention. It is a block diagram of the proposal system using mobile IP (for example, nonpatent literature 1).

Explanation of symbols

1, 2, destination LAN
3 Mobile node (MN)
4, 5 External agent 6 Home agent 7 Communication partner 8 Home LAN
9 Internet 11 Mobile Node (MN)
12 Switching server (SS)
13, 14, 15 VPN (IPSec)
100 Wireless communication terminal (MN)
111, 112, 113 Communication cards 121, 122, 123 Care-of IP address interface unit 130 Access control unit 140 Operation input unit 142 Storage unit 150 Control unit 151 Received packet consistency processing unit 152 Radio information analysis processing unit 153 Received packet analysis processing unit 154 Delay time analysis processing unit 155 Policy analysis processing unit 156 Allowable delay time / necessary bandwidth analysis unit 157 Band ratio calculation processing unit 158 Handover control unit 160 Application 161 Virtual IP address 170 Communication path selection logic unit 180 Measurement of each mobile communication delay time 190 Band distribution transmission processing unit

Claims (12)

A wireless communication device connectable to a plurality of wireless communication networks,
An uplink / downlink synchronization method for handing over an uplink and a downlink at the same time, an uplink / downlink asynchronous method for handing over an uplink and a downlink asynchronously, and other wireless communication networks while maintaining a connection with the connected wireless communication network Handover to the other wireless communication network while simultaneously connecting and performing bandwidth supplementation, and handover from the connected base station or sector to another base station or sector in the same wireless communication network A handover method selection unit that selects one of the simultaneous connection band supplement method and the other three methods based on the communication quality in the connected wireless communication network among the same network switching methods; ,
A handover control unit that controls to perform handover using the handover method selected by the handover method selection unit;
A wireless communication device comprising: The wireless communication device according to claim 1,
A policy storage unit for storing a policy regarding handover;
The handover method selector, based on the policy stored in the policy storage unit, the selection of Ha Ndooba scheme,
A wireless communication apparatus. The wireless communication device according to claim 2,
An operation input unit for setting the policy;
A wireless communication device further comprising: The wireless communication device according to claim 1,
An application information acquisition unit for acquiring at least one application information from a delay allowable time, an uplink required bandwidth, and a downlink required bandwidth from an application performing wireless communication;
The handover method selector, based on the application information acquired by the application information acquiring unit, the selection of Ha Ndooba scheme,
A wireless communication apparatus. The wireless communication device according to claim 1,
A latency storage unit that stores latency required for handover in each of the plurality of wireless communication networks, and a delay allowable time defined for each application that performs communication;
Further comprising a time comparison unit for comparing the latency stored in the latency storage unit with the allowable delay time of the application during communication,
The handover method selector, based on the comparison result by the time comparison unit and selects Ha Ndooba scheme,
A wireless communication apparatus. The wireless communication device according to claim 1,
A delay time measurement unit for measuring an average delay time of a wireless communication network during communication;
A handover destination delay time acquisition unit for acquiring an average delay time of another wireless communication network of a handover destination candidate;
A time difference calculating unit that calculates a time difference between an average delay time measured by the delay time measuring unit and an average delay time of the handover destination delay time;
A time interval as a result of adding the larger average delay time of the average delay time of the wireless communication network in communication or the average delay time of another wireless communication network of the handover destination candidate to the time difference calculated by the time difference calculation unit And a comparison unit for comparing the allowable delay time of the application,
The handover method selection unit determines whether to select the simultaneous connection band supplement method according to the comparison result by the comparison unit, or to select any one of the other three methods.
A wireless communication apparatus. In the radio | wireless communication apparatus of any one of Claims 1-6,
A communication quality monitoring unit for monitoring the communication quality of the uplink and downlink of the wireless network in communication;
A communication area monitoring unit that monitors whether the wireless communication network is within the area of another wireless communication network;
The handover method selector is also based on the communication quality unit and communication monitoring unit of the monitoring results, the selection of Ha Ndooba scheme,
A wireless communication apparatus. In the radio | wireless communication apparatus of any one of Claims 1-7,
A current value calculation unit for calculating a current value consumed by communication of each wireless communication network for each wireless communication network;
The handover method selector is also based on the current value calculated by the current value calculator, the selection of Ha Ndooba scheme,
A wireless communication apparatus. The wireless communication apparatus according to claim 8, wherein
The current value calculation unit calculates a current value consumed during transmission based on at least the transmission output and the transmission bandwidth;
A wireless communication apparatus. A method of controlling a wireless communication device connectable to a plurality of wireless communication networks,
An uplink / downlink synchronization method for handing over an uplink and a downlink at the same time, an uplink / downlink asynchronous method for handing over an uplink and a downlink asynchronously, and other wireless communication networks while maintaining a connection with the connected wireless communication network Handover to the other wireless communication network while simultaneously connecting and performing bandwidth supplementation, and handover from the connected base station or sector to another base station or sector in the same wireless communication network A handover method selection step of selecting one of the simultaneous connection band supplement method and the other three methods based on the communication quality in the connected wireless communication network among the switching methods within the same network; ,
A handover control step for controlling to perform handover using the handover method selected in the handover method selection step;
A control method for a wireless communication apparatus, comprising: Based on the communication quality in the connected wireless communication network, the handover to the other wireless communication network is performed while supplementing the bandwidth by connecting simultaneously with the other wireless communication network while maintaining the connection with the connected wireless communication network. A handover method selection unit that selects any one of the simultaneous connection band supplement method and the handover method different from the simultaneous connection band supplement method;
A handover control unit that controls to perform handover using the handover method selected by the handover method selection unit;
A wireless communication device comprising: Based on the communication quality in the connected wireless communication network, the handover method selection unit is connected to the other wireless communication network while maintaining the connection with the connected wireless communication network, and performs the bandwidth complement while performing the bandwidth supplement. Selecting any one of the simultaneous connection band supplementing method for handover to the wireless communication network and a handover method different from the simultaneous connection band supplementing method;
A handover control unit controlling to perform handover using the handover method selected by the handover method selection unit;
Control method.

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