JP5015813B2 - Wireless communication apparatus and wireless communication method - Google Patents

Description

  The present invention relates to a radio communication apparatus and a radio communication method used in a radio communication system according to an orthogonal frequency division multiple access scheme capable of providing a plurality of subchannels.

  2. Description of the Related Art In recent years, wireless communication systems that can provide a wider communication band (communication speed) have been proposed with the progress of wireless communication technology. For example, in mobile WiMAX recommended in IEEE 802.16e, by using an orthogonal frequency division multiple access scheme (OFDMA) and a time division duplex scheme (TDD), a wide bandwidth communication band can be simultaneously used for a large number of wireless communication apparatuses. Can be provided.

  In mobile WiMAX, since TDD is used, a downlink subframe and an uplink subframe are included in the same OFDM frame. Also, in the downlink subframe, allocation information to the subchannel of transmission data (data burst) in the downlink subframe, so-called DL-MAP is repeatedly transmitted from the radio base station to the radio communication device (for example, Patent Document 1).

In the wireless communication device, reception processing (demodulation processing) of the data burst addressed to the wireless communication device is executed based on the DL-MAP included in the received downlink subframe.
JP 2006-74325 A (page 5-6, FIG. 4)

  However, transmission of transmission data allocation information in the mobile WiMAX described above has the following problems. That is, in Mobile WiMAX using OFDMA, a plurality of radio base stations may transmit transmission data allocation information, specifically, DL-MAP at the same timing using the same frequency. In particular, when adopting a so-called Fully Subchannelization (FUSC) method in which available subcarriers (subchannels) are allocated to all radio base stations (cells / sectors), a plurality of adjacent radio base stations have the same frequency. In some cases, DL-MAP is transmitted at the same timing using.

  When multiple adjacent radio base stations transmit DL-MAP at the same timing using the same frequency, interference of radio signals transmitted by the multiple radio base stations occurs in areas where cells and sectors overlap. To do. For this reason, the wireless communication apparatus cannot receive the DL-MAP normally, and there is a problem that the communication quality is remarkably deteriorated.

  Therefore, the present invention has been made in view of such a situation, and continues wireless communication while avoiding deterioration of communication quality in a region where cells / sectors of a wireless communication system using OFDMA overlap. It is an object of the present invention to provide a wireless communication apparatus and a wireless communication method that can be used.

In order to solve the problems described above, the present invention has the following features. First, the first feature of the present invention is used in a radio communication system (radio communication system 200) according to an orthogonal frequency division multiple access scheme capable of providing a plurality of subchannels (subchannels CH _S ), A radio for receiving transmission data (downlink burst) allocation information (DL-MAP) from a radio base station (for example, radio base station 200A) and performing reception processing of the transmission data based on the received allocation information A communication device (wireless communication terminal 300), a repetition number detection unit (map acquisition unit 309) for detecting the number of repetitions of transmission of the allocation information repeatedly transmitted by the wireless base station, and interference of a received wireless signal An interference value acquisition unit (communication quality measurement unit) that acquires an interference value indicating a degree (for example, an interference wave level acquired based on CIR) 05), and when the number of repetitions of transmission detected by the repetition number detection unit exceeds a predetermined number and the interference value acquired by the interference value acquisition unit exceeds a predetermined threshold, The gist is to include a handover execution unit (network control unit 311) that executes a handover to another different wireless communication system (wireless communication system 100).

The second feature of the present invention is used in a radio communication system (radio communication system 200) according to an orthogonal frequency division multiple access scheme capable of providing a plurality of subchannels (subchannel CHS), and is transmitted to the subchannel. A wireless communication apparatus (receiver) that receives allocation information (DL-MAP) of data (downlink burst) from a radio base station (for example, radio base station 200A), and executes reception processing of the transmission data based on the received allocation information A wireless communication terminal 300) that indicates the number of transmission repetitions of the allocation information repeatedly transmitted by the wireless base station (map acquisition unit 309) and the degree of interference of the received wireless signal Interference value acquisition unit (communication quality measurement unit 305) that acquires an interference value (for example, an interference wave level acquired based on CIR) When the number of transmission repetitions detected by the repetition number detection unit exceeds a predetermined number and the interference value acquired by the interference value acquisition unit exceeds a predetermined threshold, the wireless communication system, and the wireless The gist is to include a communication control unit (network control unit 311) that performs wireless communication using another wireless communication system (wireless communication system 100) different from the communication system.

A third feature of the present invention is used in a radio communication system according to an orthogonal frequency division multiple access scheme capable of providing a plurality of subchannels, and receives allocation information of transmission data to the subchannels from a radio base station. A wireless communication method for performing transmission data reception processing based on the received allocation information, the step of detecting the number of repeated transmissions of the allocation information repeatedly transmitted by the radio base station, and the received radio A step of acquiring an interference value indicating a degree of signal interference, and a case in which the detected number of transmission repetitions exceeds a predetermined number and the acquired interference value exceeds a predetermined threshold, and is different from the radio communication system. And a step of executing a handover to another wireless communication system.

A fourth feature of the present invention is used in a radio communication system according to an orthogonal frequency division multiple access scheme capable of providing a plurality of subchannels, and receives allocation information of transmission data to the subchannels from a radio base station. A wireless communication method for performing transmission data reception processing based on the received allocation information, the step of detecting the number of repeated transmissions of the allocation information repeatedly transmitted by the radio base station, and the received radio An interference value indicating a degree of signal interference, and when the detected number of transmission repetitions exceeds a predetermined number and the acquired interference value exceeds a predetermined threshold, the wireless communication system, and And performing wireless communication using another wireless communication system different from the wireless communication system. .

  According to the characteristics of the present invention, there is provided a wireless communication apparatus and a wireless communication method capable of continuing wireless communication while avoiding deterioration of communication quality in a region where cells / sectors of a wireless communication system using OFDMA overlap. Can be provided.

  Next, an embodiment of the present invention will be described. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(Overall configuration of communication network)
FIG. 1 is an overall schematic configuration diagram of a communication network including a wireless communication system according to the present embodiment. As illustrated in FIG. 1, the communication network according to the present embodiment includes a backbone network 10, a wireless communication system 100, and a wireless communication system 200.

  The backbone network 10 is connected to the radio communication system 100 and the radio communication system 200.

  The wireless communication system 100 uses code division multiple access (CDMA), specifically, HRPD (high rate packet data), which is a 3GPP2 standard, as a wireless communication method.

The radio communication system 200 uses an orthogonal frequency division multiple access scheme (OFDMA) as a radio communication scheme. In the present embodiment, the wireless communication system 200 is compliant with Mobile WiMAX defined by IEEE 802.16e. In mobile WiMAX using the orthogonal frequency division multiple access scheme, a plurality of subchannels CH _S (not shown in FIG. 1, refer to FIG. 6) can be provided. In the wireless communication system 200 compliant with mobile WiMAX, a time division duplex (TDD) scheme is used.

  The radio communication system 100 includes a radio base station 100A. The radio base station 100A forms a cell C1.

  The radio communication system 200 includes radio base stations 200A and 200B. The radio base station 200A forms a cell C2A. The radio base station 200B forms a cell C2B. The cell C2A has an overlap region OL that overlaps the cell C2B. In the overlap area OL, there may be interference between the radio signal transmitted by the radio base station 200A and the radio signal transmitted by the radio base station 200B.

  Specifically, when the radio base station 200A and the radio base station 200B transmit radio signals using the same frequency at the same time, interference of the radio signals can occur.

  The cell C1 has a wider area than the cells C2A and C2B. Specifically, the cell C2A and the cell C2B are located in the cell C1.

  The wireless communication terminal 300 is a wireless communication device that can be used in the wireless communication system 100 and the wireless communication system 200. That is, the wireless communication terminal 300 supports both CDMA and OFDMA (mobile WiMAX) wireless communication systems.

  The wireless communication terminal 300 can transmit and receive VoIP (voice over IP) packets via the wireless communication system 100 or the wireless communication system 200. That is, the wireless communication terminal 300 can provide a so-called IP telephone service.

  The switching server 20 controls a communication path between the wireless communication terminal 300 and a communication destination (not shown) of the wireless communication terminal 300. Specifically, the switching server 20 can transmit an IP packet to the wireless communication terminal 300 via the wireless communication system 100 or the wireless communication system 200.

  In the wireless communication system 100, the care-of IP address is dynamically assigned to the wireless communication terminal 300 according to the position of the wireless communication terminal 300. Similarly, in the wireless communication system 200, a care-of IP address is dynamically assigned to the wireless communication terminal 300 according to the position of the wireless communication terminal 300. In the present embodiment, the care-of IP address assigned in the wireless communication system 100 and the care-of IP address assigned in the wireless communication system 200 are associated with the home IP address (virtual address) in the wireless communication terminal 300. It is done.

  Furthermore, in the present embodiment, a VPN (IPSec) tunnel is established between the switching server 20 and the wireless communication terminal 300. When the tunnel is established, OSI layer 3 virtualization is realized, and IP mobility of the wireless communication terminal 300 is ensured.

  That is, in the present embodiment, unlike the mobile IP (for example, RFC 2002), the wireless communication terminal 300 is set via the communication path set via the wireless communication system 100 and the wireless communication system 200. Communication with a communication destination (not shown) can be executed while using both communication paths simultaneously.

(Functional block configuration of wireless communication terminal 300)
FIG. 2 is a functional block configuration diagram of the wireless communication terminal 300. As illustrated in FIG. 2, the wireless communication terminal 300 includes a wireless communication unit 301, a wireless communication unit 303, a communication quality measurement unit 305, a baseband signal processing unit 307, a map acquisition unit 309, a network control unit 311, and a bandwidth calculation unit 313. And a storage unit 314.

  The radio communication unit 301 transmits / receives a radio signal according to CDMA to / from the radio base station 100A.

  The radio communication unit 303 transmits and receives radio signals according to mobile WiMAX, specifically, OFDMA and TDD, with the radio base station 200A (or the radio base station 200B).

Radio communication section 303 receives transmission data allocation information for subchannel CH _S from radio base station 200A (or radio base station 200B). Here, FIG. 6 shows a configuration example of an OFDM frame F transmitted and received between the radio base station 200A (radio base station 200B) and the radio communication terminal 300.

As shown in FIG. 6, the OFDM frame F includes a downlink subframe SF _DN used for downlink (radio base station → radio communication terminal) radio communication and an uplink (radio communication terminal → radio base station). And an uplink subframe SF _UP used for wireless communication.

In the downlink subframe SF _DN , a map area M used for transmission of DL-MAP, which is allocation information of transmission data (downlink burst) to the subchannel CH _S , is provided. Radio base station 200A (radio base station 200B) can repeatedly transmit DL-MAP having the same content.

The radio communication terminal 300 receives the DL-MAP from the radio base station 200A (radio base station 200B), and executes reception processing of transmission data (downlink burst) addressed to the own terminal based on the received DL-MAP. That is, based on the received DL-MAP, the wireless communication terminal 300 recognizes a subchannel CH _S including transmission data addressed to the terminal itself, and receives it in the corresponding subchannel CH _S (combination of frequency and time). Perform processing (such as demodulation).

  The communication quality measurement unit 305 measures the communication quality of radio signals received by the radio communication unit 301 and the radio communication unit 303. Specifically, the communication quality measurement unit 305 measures the carrier-to-interference ratio (CIR) and the signal-to-noise ratio (SNR) of the radio signal. In particular, in the present embodiment, the communication quality measuring unit 305 uses the interference value indicating the degree of interference of the radio signal received by the radio communication unit 303 from the radio base station 200A (radio base station 200B), specifically, the CIR. Based on this, the interference wave level of the radio signal is acquired. In the present embodiment, the communication quality measurement unit 305 constitutes an interference value acquisition unit.

  The baseband signal processing unit 307 is connected to the wireless communication unit 301 and the wireless communication unit 303. The baseband signal processing unit 307 executes processing related to baseband signals such as user data and control data.

  In particular, in the present embodiment, the baseband signal processing unit 307 transmits and receives IP packets based on the care-of IP address assigned to the wireless communication terminal 300 (wireless communication unit 301) in the wireless communication system 100. Similarly, the baseband signal processing unit 307 transmits and receives IP packets based on the care-of IP address assigned to the wireless communication terminal 300 (wireless communication unit 303) in the wireless communication system 200.

  In addition, as described above, in the present embodiment, since VPN based on IPSec is set, a VoIP packet transmitted between the switching server 20 and the wireless communication terminal 300 (specifically, the wireless communication terminal 300 transmits). The VoIP packet has the configuration shown in FIG. As shown in FIG. 7, the home IP address, TCP / UDP header, and payload are encapsulated and a care-of IP address is added.

  The map acquisition unit 309 acquires the DL-MAP received via the wireless communication unit 303. Also, the map acquisition unit 309 detects the DL-MAP transmission repetition count (repetition) repeatedly transmitted by the radio base station 200A (or the radio base station 200B). In the present embodiment, the map acquisition unit 309 constitutes a repetition number detection unit.

Specifically, the map acquisition unit 309 detects the number of DL-MAP transmission repetitions in the map area M (see FIG. 6) provided in the downlink subframe SF _DN . For example, the map acquisition unit 309 detects that the DL-MAP having the same content has been transmitted twice in the map area M provided in the downlink subframe SF _DN .

  Further, the map acquisition unit 309 calculates a reception success rate indicating a ratio of whether or not the DL-MAP repeatedly transmitted by the radio base station 200A (or the radio base station 200B) has been normally received. In the present embodiment, the map acquisition unit 309 constitutes a reception success rate calculation unit.

  For example, the map acquisition unit 309 calculates a reception success rate based on the number of DL-MAPs that have been successfully received within n times the OFDM frame F. Note that the map acquisition unit 309 calculates the reception success rate based on the number of transmission repetitions when the number of transmission repetitions of DL-MAP is recognized in advance, such as when the number of transmission repetitions of DL-MAP is fixed. Can do.

  The network control unit 311 executes control related to a communication network to which the wireless communication terminal 300 is connected. Specifically, the network control unit 311 executes control related to connection with a radio base station where the radio communication terminal 300 performs radio communication, that is, the radio communication system 100 or the radio communication system 200.

  In particular, in the present embodiment, the network control unit 311 causes the DL-MAP transmission repetition count detected by the map acquisition unit 309 to exceed a predetermined number, and the interference value acquired by the communication quality measurement unit 305 (to the CIR). When the interference wave level acquired based on the value exceeds a predetermined threshold value, a handover from the radio communication system 200 to the radio communication system 100 (another radio communication system) is executed. In the present embodiment, the network control unit 311 constitutes a handover execution unit.

  Specifically, the network control unit 311 satisfies the following condition when the wireless communication terminal 300 is performing wireless communication with the wireless base station 200A (or the wireless base station 200B) via the wireless communication unit 303. In this case, a handover from the wireless communication system 200 to the wireless communication system 100 is executed.

  That is, the network control unit 311 determines that the DL-MAP transmission repetition count exceeds a predetermined number (for example, 3 times) and the interference wave level of the radio signal received from the radio base station 200A (or radio base station 200B) When the predetermined threshold is exceeded, a handover to the wireless communication system 100 is executed.

  Further, the network control unit 311 can perform wireless communication by newly using the wireless communication system 100 in addition to the wireless communication system 200 used so far, instead of performing handover to the wireless communication system 100. In the present embodiment, the network control unit 311 constitutes a communication control unit.

  That is, the network control unit 311 determines that the DL-MAP transmission repetition count exceeds a predetermined number and the interference wave level of the radio signal received from the radio base station 200A (or radio base station 200B) exceeds a predetermined threshold. The radio communication system 100 and the radio communication system 200 can be used in combination.

  Specifically, the network control unit 311 causes the baseband signal processing unit 307 to transmit an IP packet to which the care-of IP address assigned in the wireless communication system 100 or the care-of IP address assigned in the wireless communication system 200 is added. The baseband signal processing unit 307 outputs a corresponding IP packet to the wireless communication unit 301 or the wireless communication unit 303. Note that in the downlink direction, the switching server 20 transmits an IP packet to which the corresponding care-of IP address is added toward the radio communication system 100 or the radio communication system 200.

  In addition, when the DL-MAP reception success rate (acquisition success rate) calculated by the map acquisition unit 309 is lower than a predetermined threshold, the network control unit 311 performs handover from the radio communication system 200 to the radio communication system 100. Execute. Note that it is preferable to more accurately determine the state of the wireless communication terminal 300 by adding whether or not the interference value acquired by the communication quality measuring unit 305 exceeds a predetermined threshold.

  Specifically, the network control unit 311 satisfies the following condition when the wireless communication terminal 300 is performing wireless communication with the wireless base station 200A (or the wireless base station 200B) via the wireless communication unit 303. In this case, a handover from the wireless communication system 200 to the wireless communication system 100 is executed.

  That is, the network control unit 311 performs a handover to the radio communication system 100 when the DL-MAP reception success rate falls below a predetermined threshold (for example, 0.3). Note that the state of the wireless communication terminal 300 is more accurately determined by determining whether or not the interference wave level of the wireless signal received from the wireless base station 200A (or the wireless base station 200B) exceeds a predetermined threshold. It is preferable.

  Further, the network control unit 311 can perform wireless communication by newly using the wireless communication system 100 in addition to the wireless communication system 200 used so far, instead of performing handover to the wireless communication system 100. That is, the network control unit 311 can also use the radio communication system 100 and the radio communication system 200 together when the DL-MAP reception success rate falls below a predetermined threshold. Note that the state of the wireless communication terminal 300 can be more accurately determined by determining whether or not the interference wave level of the wireless signal received from the wireless base station 200A (or the wireless base station 200B) exceeds a predetermined threshold. Is preferred.

  The band calculation unit 313 calculates a communication band (communication speed) required for each radio communication system when the radio communication system 100 and the radio communication system 200 are used together.

  Specifically, the band calculation unit 313 calculates the communication band based on the number of IP packets received via each wireless communication system at a predetermined time (for example, 1 second). For example, when the number of VoIP packets received per second is the same, the bandwidth calculation unit 313 substantially equalizes the communication bandwidth required for the wireless communication system 100 and the wireless communication system 200.

  The storage unit 314 stores a predetermined number that is a criterion for determining the number of transmission repetitions of the allocation information (DL-MAP) described above, a predetermined threshold that is a criterion for determining an interference value, and the like. The storage unit 314 also stores a predetermined threshold value that serves as a criterion for determining the reception success rate described above.

(Operation of wireless communication device)
Next, the operation of the wireless communication terminal 300 will be described. Specifically, an operation in which radio communication terminal 300 performs a handover to another radio communication system based on a state regarding DL-MAP included in downlink subframe SF _DN will be described.

(1) Operation example 1
FIG. 3 is a flowchart illustrating an operation in which the radio communication terminal 300 performs a handover to another radio communication system based on the DL-MAP transmission repetition count. Here, it is assumed that the wireless communication terminal 300 is performing wireless communication with the wireless base station 200A (wireless communication system 200).

As shown in FIG. 3, in step S10, the radio communication terminal 300 detects the number of DL-MAP transmission repetitions (repetition) included in the downlink subframe SF _DN .
Note that in this embodiment, the radio base station 200A (200B) causes the radio communication terminal 300 to change the cell C2A (see FIG. 1)), the number of DL-MAP transmission repetitions is increased.

  In step S20, the radio communication terminal 300 determines whether or not the DL-MAP transmission repetition count exceeds a predetermined number (for example, 3 times).

  When the DL-MAP transmission repetition count exceeds a predetermined number (YES in step S20), in step S30, the radio communication terminal 300 acquires the CIR of the radio signal received from the radio base station 200A. Furthermore, the radio communication terminal 300 acquires the interference wave level of the radio signal based on the CIR.

  In step S40, the radio communication terminal 300 determines whether or not the interference wave level of the radio signal received from the radio base station 200A exceeds a predetermined threshold value. When radio communication terminal 300 moves to overlap area OL, a radio signal received by radio communication terminal 300 from radio base station 200A may interfere with a radio signal of the same frequency transmitted by radio base station 200B. . For this reason, when the radio communication terminal 300 moves to the overlap area OL, the interference wave level of the radio signal received from the radio base station 200A may exceed a predetermined threshold.

  When the interference wave level of the radio signal received from the radio base station 200A exceeds a predetermined threshold (YES in step S40), the radio communication terminal 300 performs handover from the radio communication system 200 to the radio communication system 100 in step S50. Execute. Specifically, the radio communication terminal 300 stops radio communication with the radio base station 200A and starts radio communication with the radio base station 100A.

(2) Operation example 2
FIG. 4 is a flowchart illustrating an operation in which the radio communication terminal 300 performs a handover to another radio communication system based on the DL-MAP reception success rate (acquisition success rate). Hereinafter, differences from the operation illustrated in FIG. 3 will be mainly described.

In step S110, the radio communication terminal 300 detects the DL-MAP reception success rate (acquisition success rate) included in the downlink subframe SF _DN . For example, as described above, the wireless communication terminal 300 calculates a reception success rate (acquisition success rate) based on the number of DL-MAPs that have been successfully received within n times the OFDM frame F.

  In step S120, the radio communication terminal 300 determines whether the DL-MAP reception success rate (acquisition success rate) is below a predetermined threshold.

  When the DL-MAP reception success rate (acquisition success rate) is below a predetermined threshold (YES in step S120), in step S130, the radio communication terminal 300 causes the CIR and interference wave of the radio signal received from the radio base station 200A. Get the level.

  The operations in steps S140 and S150 are the same as the operations in steps S40 and S50 shown in FIG. The operation in step S140 can be omitted.

(3) Combined use of a plurality of radio communication systems In the operation flow described above, the radio communication terminal 300 performs a handover from the radio communication system 200 to the radio communication system 100. However, the radio communication terminal 300 Instead of the handover from the wireless communication system 100 to the wireless communication system 100, the wireless communication system 100 and the wireless communication system 200 can be used together.

  FIG. 5 shows an operation flow executed in place of the operation of step S50 shown in FIG. 3 and step S150 shown in FIG.

  As shown in FIG. 5, in step S <b> 210, the wireless communication terminal 300 calculates a communication band that needs to be complemented by the wireless communication system 100. That is, the radio communication terminal 300 supplements the radio communication system 100 with a communication band that is insufficient due to the interference wave level of the radio signal received from the radio base station 200A exceeding a predetermined threshold.

  In step S220, the wireless communication terminal 300 distributes IP packets to be transmitted to a plurality of wireless communication systems, specifically, the wireless communication system 100 and the wireless communication system 200, based on the calculated communication band.

(Action / Effect)
According to the wireless communication terminal 300, when the DL-MAP transmission repetition number (repetition) exceeds a predetermined number and the interference wave level of the received wireless signal exceeds a predetermined threshold, the wireless communication system 200 to the wireless communication system A handover to 100 is performed.

  Further, according to the radio communication terminal 300, when the DL-MAP reception success rate is below a predetermined threshold, a handover from the radio communication system 200 to the radio communication system 100 is executed. Furthermore, it is preferable to more accurately determine the state of the wireless communication terminal 300 by determining whether or not the interference wave level of the received wireless signal exceeds a predetermined threshold.

  For this reason, the radio communication terminal 300 can continue radio communication while avoiding deterioration in communication quality in an overlap area OL where cells / sectors of a radio communication system using OFDMA overlap.

Note that if the DL-MAP transmission repetition count is further increased, the DL-MAP reception success rate by the radio communication terminal 300 may increase, but the ratio of the map area M to the downlink subframe SF _DN increases, and the transmission data There is a problem that the throughput of (downstream burst) decreases. According to the wireless communication terminal 300, since the handover from the wireless communication system 200 to the wireless communication system 100 is executed before such a decrease in throughput occurs, the wireless communication terminal 300 is located in the overlap area OL. Even in this case, it is possible to maintain the necessary transmission data throughput.

  Furthermore, in this embodiment, instead of the handover from the radio communication system 200 to the radio communication system 100, the radio communication terminal 300 can also use the radio communication system 100 and the radio communication system 200 together.

  For this reason, only the communication band that is insufficient in the wireless communication system 200 can be supplemented by the wireless communication system 100.

(Other embodiments)
As described above, the content of the present invention has been disclosed through one embodiment of the present invention. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments will be apparent to those skilled in the art.

  For example, in the embodiment described above, the wireless communication system 200 is compliant with mobile WiMAX, but the wireless communication system 200 may not be mobile WiMAX as long as it is a wireless communication scheme using OFDMA.

  In the above-described embodiment, the interference wave level of the radio signal is acquired based on the CIR. However, the CIR does not necessarily have to be used as long as the parameter can determine the interference value of the radio signal. In addition, in the processing of step S40 (see FIG. 3) and step S140 (see FIG. 4), when the interference level does not exceed a predetermined threshold but the CIR falls below the predetermined threshold, a handover is executed. Also good.

  In the embodiment described above, a communication network is configured by the wireless communication system 100 and the wireless communication system 200, but the number of wireless communication systems included in the communication network may be further increased.

  In the above-described embodiment, the wireless communication apparatus according to the present invention has been described as being configured by the wireless communication terminal 300. However, the wireless communication apparatus is configured by a card module mounted on a personal computer, a portable information terminal, a car navigation system, or the like. It may be configured.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

1 is an overall schematic configuration diagram of a communication network including a wireless communication system according to an embodiment of the present invention. It is a functional block block diagram of the radio | wireless communication apparatus which concerns on embodiment of this invention. It is a flow which shows the operation | movement which the radio | wireless communication apparatus which concerns on embodiment of this invention performs the hand-over to another radio | wireless communications system based on the transmission repetition frequency of DL-MAP. It is a flow which shows the operation | movement which the radio | wireless communication apparatus which concerns on embodiment of this invention performs the hand-over to another radio | wireless communications system based on the reception success rate of DL-MAP. It is a figure which shows the operation | movement flow performed instead of operation | movement of step S50 shown in FIG. 3, and step S150 shown in FIG. It is a figure which shows the structural example of the OFDM frame which the wireless base station and wireless communication apparatus which concern on embodiment of this invention transmit / receive. It is a figure which shows the structure of the VoIP packet which the radio | wireless communication apparatus which concerns on embodiment of this invention transmits / receives.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Backbone network, 20 ... Switching server, 100 ... Wireless communication system, 100A ... Wireless base station, 200 ... Wireless communication system, 200A, 200B ... Wireless base station, 300 ... Wireless communication terminal, 301, 303 ... Wireless communication part, 305 ... communication quality measurement unit, 307 ... base band signal processing unit, 309 ... map acquisition unit, 311 ... network controller, 313 ... band calculation unit, 314 ... storage unit, C1, C2A, C2B ... cell, CH S _... sub Channel, F ... OFDM frame, M ... Map region, OL ... Overlap region, SF _DN ... Downlink subframe, _SFUP ... Uplink subframe

Claims (4)

Used in a radio communication system according to an orthogonal frequency division multiple access scheme capable of providing a plurality of subchannels, receives allocation information of transmission data to the subchannels from a radio base station, and based on the received allocation information A wireless communication device that performs reception processing of the transmission data,
A repetition number detection unit for detecting a transmission repetition number of the allocation information repeatedly transmitted by the radio base station;
An interference value acquisition unit for acquiring an interference value indicating the degree of interference of the received radio signal;
When the number of transmission repetitions detected by the repetition number detection unit exceeds a predetermined number and the interference value acquired by the interference value acquisition unit exceeds a predetermined threshold, another radio different from the radio communication system A wireless communication apparatus comprising: a handover execution unit that executes a handover to a communication system. Used in a radio communication system according to an orthogonal frequency division multiple access scheme capable of providing a plurality of subchannels, receives allocation information of transmission data to the subchannels from a radio base station, and based on the received allocation information A wireless communication device that performs reception processing of the transmission data,
A repetition number detection unit for detecting a transmission repetition number of the allocation information repeatedly transmitted by the radio base station;
An interference value acquisition unit for acquiring an interference value indicating the degree of interference of the received radio signal;
When the transmission repetition number detected by the repetition number detection unit exceeds a predetermined number and the interference value acquired by the interference value acquisition unit exceeds a predetermined threshold, the wireless communication system and the wireless communication A wireless communication apparatus comprising: a communication control unit that performs wireless communication using another wireless communication system different from the system. Used in a radio communication system according to an orthogonal frequency division multiple access scheme capable of providing a plurality of subchannels, receives allocation information of transmission data to the subchannels from a radio base station, and based on the received allocation information A wireless communication method for performing reception processing of the transmission data,
Detecting the number of transmission repetitions of the allocation information repeatedly transmitted by the radio base station;
Obtaining an interference value indicating the degree of interference of the received radio signal;
A step of executing a handover to another radio communication system different from the radio communication system when the detected number of transmission repetitions exceeds a predetermined number and the acquired interference value exceeds a predetermined threshold; A wireless communication method provided. Used in a radio communication system according to an orthogonal frequency division multiple access scheme capable of providing a plurality of subchannels, receives allocation information of transmission data to the subchannels from a radio base station, and based on the received allocation information A wireless communication method for performing reception processing of the transmission data,
Detecting the number of transmission repetitions of the allocation information repeatedly transmitted by the radio base station;
Obtaining an interference value indicating the degree of interference of the received radio signal;
When the detected number of repeated transmissions exceeds a predetermined number and the acquired interference value exceeds a predetermined threshold, wireless communication is performed using the wireless communication system and another wireless communication system different from the wireless communication system. And a step of executing communication.

Images