JP2008011259A - Radio communication system, radio base station apparatus, radio communication apparatus, and radio communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication system, radio base station apparatus, radio communication apparatus, and radio communication method for receiving data transmitted by broadcasting more securely while effectively using radio resources by broadcasting when an array antenna is used. <P>SOLUTION: A radio base station 100 when receiving a transmission request for broadcast data DT from a radio communication terminal 250B transmits a radio signal S2 including modulated broadcast data DT to the radio communication terminal 250B having transmitted the transmission request by using more array elements as compared with the case a radio signal S1 is sent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radio communication system, a radio base station apparatus, a radio communication apparatus, and a radio communication method that transmit or receive a radio signal using an array antenna including a plurality of antenna elements.

  So-called adaptive array technology that forms an appropriate directional beam according to the position of a communication partner using an array antenna composed of a plurality of antenna elements (array elements) has been introduced into various wireless communication systems. . For example, a radio base station apparatus including an array antenna can form a directional beam toward a mobile station, that is, a radio communication apparatus such as a portable radio terminal (see Patent Document 1).

In a wireless communication system using such an array antenna, the same data is transmitted from a wireless base station device to a plurality of wireless communication devices scattered by broadcast or multicast (hereinafter simply referred to as “broadcast” as appropriate). When transmitting, it is not necessary to form a directional beam using a large number of antenna elements. For this reason, an omnidirectional beam (or a beam that is not as directional as a directional beam) is formed using only one (or a part) of antenna elements.
Japanese Unexamined Patent Publication No. 2001-53662 (page 2-4, FIG. 3)

  However, the above-described conventional wireless communication system has the following problems. That is, a radio signal using an omnidirectional beam using only one (or a part) of antenna elements (hereinafter referred to as an “omnidirectional radio signal”) is a radio signal using a directional beam using multiple antenna elements ( Hereinafter, the antenna gain is low compared to “directional radio signal”). For this reason, the coverage of an omnidirectional radio signal used for data transmission by broadcasting is narrower than the coverage of a directional radio signal. That is, there is a problem that the frequency with which the wireless communication apparatus cannot receive data by broadcast increases.

  On the other hand, in order to increase the coverage of an omnidirectional radio signal, when an antenna gain is secured using a large number of antenna elements, a directional beam is formed as a result. In other words, in order to transmit broadcast data to all wireless communication devices to be transmitted (particularly, wireless communication devices located far away from the wireless base station device), the directivity in which the same data is modulated is eventually obtained. There are cases where a plurality of radio signals must be transmitted. For this reason, there exists a problem that a radio | wireless resource cannot be utilized effectively.

  Therefore, the present invention has been made in view of such a situation, and in the case of using an array antenna, it is possible to more reliably receive data transmitted by broadcasting while effectively utilizing radio resources by broadcasting. An object of the present invention is to provide a wireless communication system, a wireless base station device, a wireless communication device, and a wireless communication method.

  In order to solve the problems described above, the present invention has the following features. First, a first feature of the present invention is that a radio base that transmits a radio signal (for example, radio signal S2) using an array antenna (array antenna 101) composed of a plurality of antenna elements (array elements 101a to 101n). A wireless communication system (wireless communication system 10) including a station device (wireless base station 100) and wireless communication devices (wireless communication terminals 200A, 250A, 250B) that receive the wireless signal, wherein an omnidirectional wireless signal (Wireless signal S1) or a directional wireless signal (wireless signal S2), a wireless communication unit (wireless communication unit 102), and a transmission request receiving unit (BCMCS) that receives a transmission request (transmission request RQ) from the wireless communication device. Management section 109), and the wireless communication apparatus receives a non-directional wireless signal. Unit 265) and a transmission request transmission unit (radio communication unit 252 and transmission) that transmit the transmission request to the radio base station apparatus when the reception determination unit determines that the omnidirectional radio signal cannot be received. A request generation unit 267) and a directional radio signal reception unit (radio communication unit 252) that receives the directional radio signal transmitted by the radio communication unit, wherein the radio communication unit includes a plurality of radio communication units. When transmitting the same data (broadcast data DT) to the apparatus, the omnidirectional radio signal modulated with the data is transmitted, and when the transmission request receiving unit receives the transmission request, the transmission request is transmitted. The gist is to transmit a directional radio signal in which the data is modulated to the transmitted radio communication apparatus.

  According to such a wireless communication system, when the same data is transmitted to a plurality of wireless communication devices, an omnidirectional wireless signal in which the data is modulated is transmitted. Since non-directional radio signals have no directivity (or weak directivity), the wireless base station device transmits the same data simultaneously to a plurality of scattered wireless communication devices, that is, transmits by broadcast. Can do. For this reason, it is possible to effectively use radio resources.

  On the other hand, the directional radio signal reaches farther than the omnidirectional radio signal because it has an antenna gain due to the use of a plurality of antenna elements. For this reason, even when the wireless communication apparatus moves outside the reachable range of the omnidirectional wireless signal, the wireless communication apparatus transmits (specifically, retransmits) the data to the wireless base station apparatus using the directional wireless signal, thereby Data can be received.

  A second feature of the present invention is a radio base station apparatus that transmits a radio signal to a radio communication apparatus using an array antenna including a plurality of antenna elements, and is an omnidirectional radio signal or a directional radio signal A wireless communication unit that transmits a transmission request and a transmission request receiving unit that receives a transmission request from the wireless communication device, and the wireless communication unit transmits the same data to a plurality of the wireless communication devices, A directional radio signal in which the data is modulated is transmitted to the radio communication apparatus that has transmitted the transmission request when the omnidirectional radio signal in which data is modulated is transmitted and the transmission request receiving unit receives the transmission request. The gist is to send.

  A third feature of the present invention relates to the second feature of the present invention, wherein a modulation rate from the data to the directional radio signal (e.g., equivalent to 24QAM) is calculated from the data to the omnidirectional radio signal. The gist is that it is higher than the modulation rate (e.g., equivalent to 12QAM).

  A fourth feature of the present invention is that an omnidirectional wireless signal in which a directional wireless signal is transmitted using an array antenna including a plurality of antenna elements or the same data is modulated toward a plurality of transmission destinations. A radio communication apparatus that receives the directional radio signal or the omnidirectional radio signal from a radio base station apparatus capable of transmitting a signal, and whether or not the omnidirectional radio signal is received And a transmission request transmission unit that transmits the data transmission request to the radio base station device when the reception determination unit determines that the omnidirectional radio signal is not received. The gist is to receive the directional radio signal from the radio base station apparatus by transmitting the retransmission request.

  A fifth feature of the present invention relates to the fourth feature of the present invention, wherein a modulation rate from the data to the directional radio signal is higher than a modulation rate from the data to the omnidirectional radio signal. Is the gist.

  A sixth feature of the present invention relates to the fourth or fifth feature of the present invention, wherein the reception determination unit is configured such that the wireless communication device is located outside a reachable range (coverage C1) of the omnidirectional wireless signal. In this case, the gist is to determine whether or not the omnidirectional radio signal can be received at a predetermined period.

  A seventh feature of the present invention is a wireless communication method for transmitting and receiving a wireless signal using an array antenna composed of a plurality of antenna elements. When transmitting the same data to a plurality of transmission destinations, there is no need. Transmitting the directional radio signal; receiving the data transmission request from the destination; and receiving the transmission request, the data is modulated to the wireless communication device that transmitted the transmission request. The present invention includes a step of transmitting a directional radio signal and a step of receiving the directional radio signal by the transmission destination.

  An eighth feature of the present invention relates to the seventh feature of the present invention, wherein in the step of determining whether or not the omnidirectional radio signal is received, and in the step of determining, the omnidirectional radio signal is The gist further includes a step of transmitting the transmission request to a transmission source of the omnidirectional radio signal when it is determined that reception is not possible.

  According to the features of the present invention, in the case of using an array antenna, a radio communication system, a radio base station apparatus, and a radio base station apparatus capable of more reliably receiving data transmitted by broadcast while effectively utilizing radio resources by broadcast A wireless communication device and a wireless communication method 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 schematic configuration of wireless communication system)
FIG. 1 is an overall schematic configuration diagram of a wireless communication system 10 according to the present embodiment. As shown in FIG. 1, the radio communication system 10 includes a radio base station 100 (radio base station apparatus) and radio communication terminals 200A, 250A, 250B (radio communication apparatuses). The wireless communication system 10 is compliant with “iBurst” using TDMA and SDMA / TDD systems. Note that the numbers of radio base stations and radio communication terminals constituting the radio communication system 10 are not limited to the numbers shown in FIG.

  The radio base station 100 transmits radio signals S1 and S2 using the array antenna 101 (not shown in FIG. 1, refer to FIG. 2). Specifically, the radio base station 100 uses only one of the array elements (for example, the array element 101a) among the array elements 101a to 101n (not shown in FIG. 1, refer to FIG. 2) constituting the array antenna 101. It is possible to transmit a radio signal S1 (omnidirectional radio signal).

  The radio signal S1 transmitted using only one of the array elements forms an omnidirectional beam (not shown) having no directivity and is emitted toward all directions. In the present embodiment, the wireless signal S1 is transmitted as broadcast data DT (not shown in FIG. 1, refer to FIG. 2) by a broadcast multicast service (BCMCS) that transmits the same data simultaneously to a plurality of wireless communication terminals. Used for. The data transmitted as the broadcast data DT includes, for example, broadcast type content data. The broadcast data DT is transmitted by broadcast (or multicast) except in the case of retransmission described later.

  In addition, the radio base station 100 can transmit the radio signal S2 (directional radio signal) using all of the array elements 101a to 101n (12 in total) constituting the array antenna 101. A radio signal S2 transmitted using all of the array elements 101a to 101n forms a directional beam B1 having directivity (beamforming), and is radiated toward a specific radio communication terminal.

  In the present embodiment, the radio signal S2 is used for data transmission to a specific radio communication terminal and retransmission of broadcast data DT transmitted by the radio signal S1 to the specific radio communication terminal. Note that, when the broadcast data DT is retransmitted by the radio signal S2, unicast is used instead of broadcast (or multicast).

  The radio signal S1 transmitted using only one of the array elements has no antenna gain due to the use of the plurality of array elements, and covers up to the coverage C1. On the other hand, the radio signal S2 transmitted using all of the array elements 101a to 101n reaches farther than the radio signal S1 because of the antenna gain due to the use of a plurality of array elements. Specifically, the radio signal S2 can cover up to the coverage C2.

  Radio communication terminals 200A, 250A, 250B receive radio signals S1, S2 transmitted by radio base station 100.

  The wireless communication terminal 200A is a notebook personal computer, and is equipped with a wireless communication card module compliant with the iBurst (registered trademark) standard. The wireless communication terminals 250A and 250B are personal digital assistants (PDAs), and are equipped with wireless communication card modules compliant with the iBurst standard.

(Functional block configuration of wireless communication system)
Next, a functional block configuration of the wireless communication system 10 will be described. FIG. 2 is a functional block configuration diagram of the radio base station 100. FIG. 3 is a functional block configuration diagram of the wireless communication terminal 250B. Note that the wireless communication terminals 200A and 200B also have the same functional block configuration as the wireless communication terminal 250B. It should be noted that the radio base station 100 and the radio communication terminal 250B may include blocks (such as a power supply unit) that are not shown in the drawing or that are not illustrated in order to realize the function as the device.

(1) Radio base station 100
As shown in FIG. 2, the radio base station 100 includes an array antenna 101, a radio communication unit 102, an array antenna control unit 103, a data processing unit 105, a communication interface unit 107, and a BCMCS management unit 109.

  The array antenna 101 includes array elements 101a to 101n (antenna elements). Specifically, the array antenna 101 is configured by a total of 12 array elements. The array antenna 101 is connected to the wireless communication unit 102.

  The wireless communication unit 102 transmits wireless signals S1 and S2 of a predetermined frequency band (for example, 1.79 GHz band) and receives a wireless signal (not shown) transmitted by a wireless communication terminal.

  Specifically, when the wireless communication unit 102 transmits the same data (broadcast data DT) to a plurality of wireless communication terminals, the broadcast data DT is modulated based on control by the array antenna control unit 103. A radio signal S1 is transmitted. Further, when the BCMCS management unit 109 receives a broadcast data DT transmission request RQ from a specific wireless communication terminal, the wireless communication unit 102 transmits the transmission request RQ based on the control by the array antenna control unit 103. Radio signal S2 modulated with broadcast data DT is transmitted to the communication terminal.

  Further, the wireless communication unit 102 modulates the baseband signal output from the data processing unit 105, or demodulates the received wireless signal into a baseband signal and outputs the baseband signal to the data processing unit 105.

  In the present embodiment, the wireless communication unit 102 supports an adaptive modulation scheme, and can select 24QAM, 16QAM, 12QAM, 8PSK, and the like according to the state of the wireless signal. Specifically, the radio communication unit 102 can apply different modulation schemes for the radio signal S1 and the radio signal S2. For example, the wireless communication unit 102 can apply 24QAM as a modulation method from the broadcast data DT to the wireless signal S2. On the other hand, the wireless communication unit 102 can apply 12QAM as a modulation method from the broadcast data DT to the wireless signal S1. That is, the wireless communication unit 102 can make the modulation rate (about 1,061 kbps) from the broadcast data DT to the radio signal S2 higher than the modulation rate (about 787 kbps) from the broadcast data DT to the radio signal S1.

  The array antenna control unit 103 controls the array antenna 101. Specifically, the array antenna control unit 103 is directed to the wireless communication terminal (for example, the wireless communication terminal 250B) that has transmitted the wireless signal based on the correlation between the wireless signals received by the array elements 101a to 101n. The amplitude and phase of the radio signal S2 transmitted in this manner are controlled.

  In the present embodiment, when transmitting the same data (broadcast data DT) to a plurality of wireless communication terminals, the array antenna control unit 103 transmits a wireless signal S1 obtained by modulating the broadcast data DT to a specific wireless communication terminal. The wireless communication unit 102 is caused to transmit using fewer array elements (for example, one) than when transmitting a destination wireless signal (for example, 12).

  Also, the array antenna control unit 103 has more array elements (for example, 12) than when the BCMCS management unit 109 receives the transmission request RQ for the broadcast data DT from a specific wireless communication terminal than when the wireless signal S1 is transmitted. , The wireless communication terminal that has transmitted the transmission request RQ is caused to transmit the wireless signal S2 modulated with the broadcast data DT to the wireless communication unit 102.

  As described above, since the radio signal S2 is transmitted using more array elements than the radio signal S1, the radio signal S2 has higher directivity than the radio signal S1 and forms a directional beam B1 (see FIG. 1). Further, since the radio signal S2 has an antenna gain due to the use of a plurality of array elements, the radio signal S2 reaches farther than the radio signal S1. The radio signal S2 is transmitted according to an individual communication channel used with the radio communication terminal.

  Furthermore, when the number of wireless communication terminals requesting reception of broadcast data DT notified from the BCMCS management unit 109 is less than a predetermined threshold (for example, 5), the array antenna control unit 103 performs broadcast using the wireless signal S1. Transmission of data DT can be stopped. In this case, the array antenna control unit 103 may transmit the broadcast data DT to each wireless communication terminal requesting reception of the broadcast data DT using the wireless signal S2 instead of the wireless signal S1.

  The data processing unit 105 executes processing related to the baseband signal, specifically, various data (user data and control data). In particular, in the present embodiment, the data processing unit 105 transmits the broadcast data DT to a plurality of wireless communication terminals at predetermined intervals.

  The communication interface unit 107 is connected to the data processing unit 105. The communication interface unit 107 provides a communication interface necessary for connecting to a wired backbone network (not shown) to which the radio base station 100 is connected.

  The BCMCS management unit 109 manages the transmission state of broadcast data DT by BCMCS. In particular, in the present embodiment, the BCMCS management unit 109 can receive a transmission request RQ for broadcast data DT from a specific wireless communication terminal. In the present embodiment, the BCMCS management unit 109 constitutes a transmission request receiving unit.

  The BCMCS management unit 109 notifies the array antenna control unit 103 that the transmission request RQ has been received and information indicating the wireless communication terminal that has transmitted the transmission request RQ.

  Further, the BCMCS management unit 109 can receive a notification indicating whether or not the wireless communication terminal requests reception of the broadcast data DT from the wireless communication terminal. The BCMCS management unit 109 can also provide the array antenna control unit 103 with the number of wireless communication terminals that are requesting reception of the broadcast data DT.

(2) Wireless communication terminal 250B
As shown in FIG. 3, the wireless communication terminal 250B includes an antenna 251, a wireless communication unit 252, a transmission data processing unit 253, a reception data processing unit 255, and a BCMCS information reception management unit 260.

  The antenna 251 is connected to the wireless communication unit 252. The antenna 251 is configured by a single antenna element, not an array antenna.

  The radio communication unit 252 receives the radio signals S <b> 1 and S <b> 2 transmitted by the radio base station 100 or transmits a radio signal toward the radio base station 100. In the present embodiment, the wireless communication unit 252 constitutes a directional wireless signal receiving unit.

  Further, the wireless communication unit 252 modulates the baseband signal output from the transmission data processing unit 253, demodulates the received wireless signals S1 and S2 into baseband signals, and outputs the baseband signal to the reception data processing unit 255. .

  The transmission data processing unit 253 executes processing related to a baseband signal, specifically, various types of transmission data (user data and control data). The transmission data processing unit 253 is connected to the BCMCS information reception management unit 260. Based on the transmission request RQ output from the BCMCS information reception management unit 260, the transmission data processing unit 253 generates a baseband signal including the transmission request RQ, specifically, the uplink frame F (see FIG. 5). be able to.

  The reception data processing unit 255 performs processing related to baseband signals, specifically, various reception data (user data and control data). In particular, in the present embodiment, the reception data processing unit 255 performs reception processing of broadcast data DT transmitted by the radio base station 100.

  The BCMCS information reception management unit 260 includes a BCMCS information storage unit 261, a reception operation control unit 263, a transmission request determination unit 265, a transmission request generation unit 267, and a BCMCS reception notification unit 269.

  The BCMCS information storage unit 261 stores information related to broadcast data DT by BCMCS. Specifically, the BCMCS information storage unit 261 stores the transmission frequency of the broadcast data DT (the number of times of content transmission), the transmission interval, and information on the radio signal to be used (channel, etc.).

  The reception operation control unit 263 controls the reception operation of the broadcast data DT by BCMCS. Specifically, the reception operation control unit 263 activates the reception data processing unit 255 at a predetermined timing based on the information stored in the BCMCS information storage unit 261, and sends the broadcast data DT to the reception data processing unit 255. Receive. Further, the reception operation control unit 263 stores a reception error of the broadcast data DT in the BCMCS information storage unit 261 when the reception data processing unit 255 does not receive the broadcast data DT at a predetermined interval.

  The transmission request determination unit 265 determines whether to request transmission (retransmission) of the broadcast data DT. Specifically, the transmission request determination unit 265 uses the information stored in the BCMCS information storage unit 261 to generate the radio signal S1 used for transmission of the broadcast data DT and the reception data processing unit 255 at a predetermined cycle. It is determined whether it is received. In the present embodiment, the transmission request determination unit 265 constitutes a reception determination unit. The transmission request determination unit 265 notifies the transmission request generation unit 267 that the broadcast data DT cannot be received when the number of times the reception data processing unit 255 cannot receive the broadcast data DT at a timing corresponding to a predetermined period continues for a predetermined number of times. To do.

  Further, the transmission request determination unit 265 determines whether or not the wireless signal S1 can be received at a predetermined period even when the wireless communication terminal 250B is located within the reach of the wireless signal S1, that is, outside the coverage C1. You can also.

  When the transmission request determination unit 265 determines that the radio signal S1 cannot be received at a predetermined period, the transmission request generation unit 267 transmits a transmission request RQ for the broadcast data DT that could not be received to the radio base station 100. . In the present embodiment, the wireless communication unit 252 and the transmission request generation unit 267 constitute a transmission request transmission unit.

  Specifically, when receiving a notification indicating that broadcast data DT cannot be received from the transmission request determination unit 265, the transmission request generation unit 267 generates a transmission request RQ, and transmits the generated transmission request RQ to the wireless communication unit 252. To send to. In the present embodiment, as shown in FIG. 5, 1 bit of the information symbol portion of the uplink frame F of iBurst is assigned as a BCMCS flag bit. When transmitting the transmission request RQ to the radio base station 100, the transmission request generation unit 267 sets the BCMCS flag bit to “1”.

  The BCMCS reception notifying unit 269 notifies the radio base station 100 that the radio communication terminal 250B is requesting reception of the broadcast data DT. For example, the BCMCS reception notifying unit 269 notifies the radio base station 100 that the reception of the broadcast data DT is requested using one bit of the information symbol portion of the uplink frame F, similarly to the BCMCS flag bit. You can be notified.

(Operation of wireless communication system)
Next, the operation of the above-described wireless communication system will be described. Specifically, the reception operation of the broadcast data DT by the wireless communication terminal 250B will be described. FIG. 4 shows a transmission / reception operation flow of broadcast data DT by the radio base station 100 and the radio communication terminal 250B.

  As shown in FIG. 4, in step S10, the radio communication terminal 250B determines whether or not the radio signal S1 in which the broadcast data DT is modulated is received from the radio base station 100.

  When the wireless signal S1 is received (YES in step S10), in step S20, the wireless communication terminal 250B executes information reproduction processing based on the received broadcast data DT (for example, reproduction of broadcast-type content).

  When the wireless signal S1 is not received (NO in step S10), in step S30, the wireless communication terminal 250B determines whether the reception timing of the broadcast data DT has elapsed. Specifically, radio communication terminal 250B determines whether or not the reception timing of broadcast data DT has elapsed based on the reception cycle (predetermined cycle) of broadcast data DT.

  When the reception timing of the broadcast data DT has elapsed (YES in step S30), in step S40, the wireless communication terminal 250B stores that reception of the broadcast data DT has failed. An example of the cause of failure in receiving broadcast data DT is that wireless communication terminal 250B has moved out of coverage C1.

  In step S50, the radio communication terminal 250B determines whether or not the reception failure of the broadcast data DT has continued N times.

  When the failure in receiving broadcast data DT continues N times (YES in step S50), in step S60, radio communication terminal 250B transmits to radio base station 100 a transmission request RQ for broadcast data DT that could not be received. Specifically, the radio communication terminal 250B transmits the transmission request RQ to the radio base station 100 by setting the BCMCS flag bit of the uplink frame F (see FIG. 5) to “1”.

  In the present embodiment, the value of N is known in the radio base station 100, and when the radio base station 100 receives the transmission request RQ, the radio base station 100 uses the broadcast data from which position the radio communication terminal 250B It is possible to recognize whether DT has not been received. When receiving the transmission request RQ from the radio communication terminal 250B, the radio base station 100 broadcasts not the radio signal S1 that forms the omnidirectional beam but the radio signal S2 that forms the directional beam B1 (see FIG. 1). Data DT is transmitted (retransmitted) to wireless communication terminal 250B.

  If the failure to receive the broadcast data DT has not continued N times (NO in step S50), the wireless communication terminal 250B repeats the processing from step S10.

  In step S65, based on the reception of the transmission request RQ from the wireless communication terminal 250B, the radio base station 100 switches the transmission of the broadcast data DT transmitted by the BCMCS to the transmission by unicast.

  In step S70, the radio communication terminal 250B receives the radio signal S2 in which the broadcast data DT is modulated from the radio base station 100. That is, wireless communication terminal 250B receives data having the same content as broadcast data DT retransmitted by unicast, using wireless signal S2.

  In step S80, the wireless communication terminal 250B executes information reproduction processing based on the received broadcast data DT.

(Action / Effect)
According to the wireless communication system 10 described above, when the same broadcast data DT is transmitted to a plurality of wireless communication terminals, the broadcast data DT is generated using fewer array elements than when transmitting a normal wireless signal. The modulated radio signal S1 is transmitted. Since the radio signal S1 transmitted using a smaller number of array elements than when transmitting a normal radio signal has no directivity, the radio base station 100 transmits the same broadcast data to a plurality of scattered radio communication terminals. DT can be transmitted simultaneously. For this reason, it is possible to effectively use radio resources.

  On the other hand, the radio signal S2 transmitted using more array elements than when transmitting the radio signal S1 has an antenna gain due to the use of a plurality of array elements, and thus reaches farther than the radio signal S1. Therefore, even when the wireless communication terminal moves out of the reachable range of the wireless signal S1, the broadcast data DT is reliably received by transmitting (retransmitting) the broadcast data DT to the wireless base station 100 using the wireless signal S2. can do.

  In the present embodiment, the modulation rate (about 1,061 kbps) from the broadcast data DT to the radio signal S2 can be higher than the modulation rate (about 787 kbps) from the broadcast data DT to the radio signal S1. When reception of the broadcast data DT by the radio signal S1 fails, the radio communication terminal receives the radio signal S2 in which the broadcast data DT is modulated, so that it can be received in a shorter time than the reception of the broadcast data DT by the radio signal S1. A lot of broadcast data DT can be received.

  Therefore, the radio communication terminal can catch up with the transmission schedule of the broadcast data DT by the radio signal S1 by continuing to receive the radio signal S2 in which the broadcast data DT is modulated. That is, when a wireless communication terminal outside the reachable range (coverage C1) of the wireless signal S1 reenters the coverage C1, the user of the wireless communication terminal is made aware of switching from the wireless signal S2 to the wireless signal S1. Without receiving the broadcast data DT by the radio signal S1.

  In the present embodiment, the radio communication terminal can determine whether or not the radio signal S1 can be received at a predetermined period when it is located outside the coverage area of the radio signal S1, that is, outside the coverage C1. For this reason, when the wireless communication terminal enters the coverage C1, reception of the broadcast data DT by the wireless signal S1 can be started promptly.

  In the present embodiment, the radio base station 100 stops transmission of the broadcast data DT using the radio signal S1 when the number of radio communication terminals requesting reception of the broadcast data DT is below a predetermined threshold (for example, 5). can do.

  In this case, the radio communication terminal transmits a broadcast data DT transmission request RQ to the radio base station 100 according to the above-described operation flow. Therefore, the radio base station 100 transmits the broadcast data DT to each radio communication terminal that requests the broadcast data DT by the radio signal S2 instead of the radio signal S1. That is, when the number of wireless communication terminals requesting reception of broadcast data DT is extremely small, the transmission of data by broadcast using the radio signal S1 is stopped, and the transmission of data by unicast using the radio signal S2 is stopped. You can choose.

(Other embodiments)
As described above, the contents of the present invention have 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 above-described embodiment, the wireless signal S1 is transmitted using only one of the array elements. However, the number of array elements is smaller than that in the case of transmitting normal wireless signals (for example, 12). If so, the radio signal S1 may be transmitted using a plurality of array elements (for example, two).

  In the above-described embodiment, the radio signal S2 is transmitted using the array elements 101a to 101n (12). However, if more array elements are used than when the radio signal S1 is transmitted, The radio signal S2 may be transmitted using less than 12 array elements (for example, 8).

  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 wireless communication system according to an embodiment of the present invention. It is a functional block block diagram of the radio base station apparatus which concerns on embodiment of this invention. It is a functional block block diagram of the radio | wireless communication apparatus which concerns on embodiment of this invention. It is an operation | movement flowchart of the radio | wireless communication apparatus which concerns on embodiment of this invention. It is a block diagram of the uplink frame used in the radio | wireless communications system which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Wireless communication system, 100 ... Wireless base station, 101 ... Array antenna, 101a-101n ... Array element, 102 ... Wireless communication part, 103 ... Array antenna control part, 105 ... Data processing part, 107 ... Communication interface part, 109 ... BCMCS management unit, 200A, 250A, 250B ... wireless communication terminal, 251 ... antenna, 252 ... radio communication unit, 253 ... transmission data processing unit, 255 ... reception data processing unit, 260 ... BCMCS information reception management unit, 261 ... BCMCS Information storage unit, 263 ... reception operation control unit, 265 ... transmission request determination unit, 267 ... transmission request generation unit, 269 ... BCMCS reception notification unit, B1 ... directional beam, C1, C2 ... coverage, DT ... broadcast data, F ... uplink frame, RQ ... transmission request, S1, S2 ... radio signal

Claims (8)

A wireless communication system including a wireless base station device that transmits a wireless signal using an array antenna configured by a plurality of antenna elements, and a wireless communication device that receives the wireless signal,
The wireless base station device
A wireless communication unit that transmits an omnidirectional radio signal or a directional radio signal;
A transmission request receiving unit for receiving a transmission request from the wireless communication device;
With
The wireless communication device
A reception determination unit that determines whether or not the omnidirectional radio signal is received;
When it is determined by the reception determination unit that the omnidirectional radio signal cannot be received, a transmission request transmission unit that transmits the transmission request to the radio base station device;
A directional radio signal receiving unit that receives the directional radio signal transmitted by the radio communication unit;
The wireless communication unit
When transmitting the same data to a plurality of the wireless communication devices, transmitting an omnidirectional radio signal in which the data is modulated,
When the transmission request receiving unit receives the transmission request, a wireless communication system that transmits a directional wireless signal in which the data is modulated to the wireless communication device that has transmitted the transmission request. A radio base station apparatus that transmits a radio signal to a radio communication apparatus using an array antenna constituted by a plurality of antenna elements,
A wireless communication unit that transmits an omnidirectional radio signal or a directional radio signal;
A transmission request receiving unit for receiving a transmission request from the wireless communication device;
The wireless communication unit
When transmitting the same data to a plurality of the wireless communication devices, transmitting an omnidirectional radio signal in which the data is modulated,
When the transmission request receiving unit receives the transmission request, a radio base station apparatus that transmits a directional radio signal in which the data is modulated to the radio communication apparatus that has transmitted the transmission request.   The radio base station apparatus according to claim 2, wherein a modulation rate from the data to the directional radio signal is higher than a modulation rate from the data to the omnidirectional radio signal. Using an array antenna composed of a plurality of antenna elements, it is possible to transmit a directional radio signal or transmit an omnidirectional radio signal in which the same data is modulated to a plurality of transmission destinations. A wireless communication device that receives the directional wireless signal or the omnidirectional wireless signal from a wireless base station device,
A reception determination unit that determines whether or not the omnidirectional radio signal is received;
When it is determined by the reception determination unit that the omnidirectional radio signal cannot be received, a transmission request transmission unit that transmits the data transmission request to the radio base station device,
A radio communication apparatus that receives the directional radio signal from the radio base station apparatus by transmitting the retransmission request.   The radio communication apparatus according to claim 4, wherein a modulation rate from the data to the directional radio signal is higher than a modulation rate from the data to the omnidirectional radio signal.   The reception determination unit determines whether or not the omnidirectional radio signal can be received at a predetermined cycle when the wireless communication device is located outside the reachable range of the omnidirectional radio signal. 5. The wireless communication device according to 5. A wireless communication method for transmitting and receiving a wireless signal using an array antenna composed of a plurality of antenna elements,
A step of transmitting an omnidirectional radio signal when transmitting the same data to a plurality of destinations;
Receiving a transmission request for the data from the destination;
When receiving the transmission request, transmitting a directional wireless signal in which the data is modulated to the wireless communication device that has transmitted the transmission request;
A wireless communication method comprising: the transmission destination receiving the directional wireless signal. Determining whether the omnidirectional radio signal is received;
The wireless communication according to claim 7, further comprising: transmitting the transmission request to a transmission source of the omnidirectional wireless signal when it is determined that the omnidirectional wireless signal cannot be received in the determining step. Communication method.

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