JP2008211686A - Wireless communication system, wireless communication device, and wireless communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication system for further surely calculating a transmission weight, applied to a wireless signal to be transmitted, regardless of a position of a communication destination or a bandwidth of a frequency band to be assigned, a wireless communication device, and a wireless communication method. <P>SOLUTION: A wireless base station 100A is provided with a communication quality determination part 107, which determines whether or not the communication quality of an up-link wireless signal is below a prescribed threshold, and a frame control part 111 that transmits a change command for commanding the extension of a transmission period of a down-link preamble to a wireless communication terminal while narrowing a frequency band of the down-link preamble when determined by the communication quality determination part 107 that the communication quality is below the prescribed threshold. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radio communication system for calculating a transmission weight applied to a transmission radio signal to be transmitted to a communication destination using a known signal that is included in a reception radio signal received from the communication destination and whose setting value is known, and a radio The present invention relates to a communication device and a wireless communication method.

  In a wireless communication system such as mobile WiMAX, adaptive array control is introduced for the purpose of increasing the number of wireless communication terminals with which wireless base stations can communicate at the same time. In adaptive array control, a radio base station transmits a radio signal (transmission) to a radio communication terminal using a preamble (known signal) included in a radio signal (received radio signal) received from a communication destination, that is, a radio communication terminal. The weight applied to the wireless signal is calculated (for example, Patent Document 1).

  Further, in a wireless communication system that employs time division duplex (TDD), such as mobile WiMAX, and uses the same frequency band in the uplink and downlink directions, a preamble included in a radio signal received from a radio communication terminal is used. The calculated weight (reception weight) can be used as it is as a weight (transmission weight) adapted to a radio signal transmitted to the radio communication terminal.

  Thus, when the reception weight is used as it is as the transmission weight, it is necessary that the same frequency is used in the upstream direction and the downstream direction. However, it is common that the frequency band assigned in the downlink direction is wider than the uplink direction.

Therefore, a method of including an uplink preamble and a downlink preamble in the radio signal transmitted by the radio communication terminal is conceivable. The downlink preamble is arranged so as to correspond to the frequency band allocated in the downlink direction.
Japanese Patent No. 3800074 (page 6, FIG. 1)

  However, in the preamble arrangement method described above, if the frequency band of the “downlink preamble” included in the radio signal transmitted by the radio communication terminal is expanded in accordance with the frequency band allocated in the downlink direction, Power spreads and power density decreases. For this reason, there is a problem that the communication quality of the radio signal received by the radio base station is deteriorated and the reception weight and the transmission weight cannot be calculated accurately.

  In order to solve such a problem, the transmission power of the wireless signal transmitted by the wireless communication terminal may be increased, but this is not preferable because the battery mounted on the wireless communication terminal is consumed quickly.

  Also, even when the wireless communication terminal is located in the vicinity of self-ringing away from the wireless base station, the communication quality of the wireless signal received by the wireless base station is reduced, and the reception weight and transmission weight are normally calculated. There is a problem that can not be.

  Therefore, the present invention has been made in view of such a situation, and more reliably calculates a transmission weight applied to a radio signal to be transmitted regardless of the position of a communication destination and the frequency band to be allocated. An object of the present invention is to provide a wireless communication system, 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 that a radio communication terminal (radio communication terminal) that transmits a radio signal (uplink radio signal SUP) including known signals (uplink preamble PUL, downlink preamble PDL) whose set values are known. 200) and a radio base station that calculates a transmission weight applied to a radio signal (downlink radio signal SDN) transmitted to the radio communication terminal using the known signal included in the radio signal received from the radio communication terminal (For example, wireless base station 100A), wherein the wireless base station determines whether the communication quality of the wireless signal received from the wireless communication terminal falls below a predetermined threshold value. A communication quality determination unit (communication quality determination unit 107) for determining whether or not the communication quality is lower than the predetermined threshold. If so, the wireless communication terminal is instructed to change the known signal frequency band (frequency band BW3), which is the frequency band of the known signal, and to extend the transmission period (period T1) of the known signal. A known signal control unit (frame control unit 111) for transmitting, wherein the wireless communication terminal receives a change instruction receiving unit (baseband processing unit 203) that receives the change instruction, and the change instruction receiving unit receives the change instruction Based on a change instruction, the known signal frequency band is narrowed and the known change signal (for example, DL-P31 to DL-P33) in which the transmission period of the known signal is extended is transmitted to the radio base station. And a base unit (baseband processing unit 203 and frame control unit 205).

  According to such a radio communication system, when it is determined that the communication quality (for example, received power intensity) of a radio signal received by a radio base station from a radio communication terminal is below a predetermined threshold, the frequency band of the known signal is In addition to being narrowed, the transmission period of the known signal is extended.

  When the frequency band of the known signal is narrowed, the reception power density of the known signal increases. For this reason, even when the communication quality of the radio signal received by the radio base station from the radio communication terminal deteriorates, the known signal can be reliably received. Further, since the transmission period of the known signal is extended, the radio base station can receive the known signal necessary for calculating the transmission weight even when the frequency band of the known signal is narrowed.

  The second feature of the present invention is to use a known signal (downlink preamble PDL) that is included in a received radio signal (uplink radio signal SUP) received from a communication destination (wireless communication terminal 200) and whose set value is known. A radio communication apparatus (for example, radio base station 100A) that calculates a transmission weight applied to a transmission radio signal (downlink radio signal SDN) to be transmitted to the communication destination, and the communication quality of the reception radio signal is a predetermined value When the communication quality determination unit (communication quality determination unit 107) determines whether the communication quality is lower than the threshold, and the communication quality determination unit determines that the communication quality is lower than the predetermined threshold, the frequency band of the known signal The known signal frequency band (frequency band BW3) is narrowed, and a change instruction for instructing to extend the transmission period (period T1) of the known signal is transmitted to the communication destination. And gist further comprising known signal control unit (frame control section 111) that.

  A third feature of the present invention relates to the second feature of the present invention, wherein the known signal control unit is included in the known signal frequency band and is narrower than the known signal frequency band (frequency band BW31). To BW33), instructing to sequentially transmit a plurality of change known signals (for example, DL-P31 to DL-P33) from the communication destination in the extended transmission period (period T2), and the change known signal The above is summarized in that the narrow frequency bands are different from each other, and the total frequency band obtained by summing the narrow frequency bands of the plurality of changed known signals is equivalent to the known signal frequency band.

  A fourth feature of the present invention relates to the third feature of the present invention, wherein the narrow frequency band is 1 / n (for example, 1/3) of the known signal frequency band, and the transmission period is extended. Is summarized as being n times (for example, 3 times) the transmission period before extension.

  A fifth feature of the present invention is that a radio signal (uplink radio signal SUP) including a known signal (uplink preamble PUL, downlink preamble PDL) having a set value is known to a communication destination (for example, radio base station 100A). A wireless communication device (wireless communication terminal 200) for transmitting, wherein the known signal frequency band (frequency band BW3), which is the frequency band of the known signal, is narrowed and the transmission period (period T1) of the known signal is extended. Based on the change instruction received by the change instruction receiving unit (baseband processing unit 203) and the change instruction receiving unit, the known signal frequency band is narrowed and the known signal is transmitted. A known signal transmission unit that transmits a radio signal including a changed known signal (for example, DL-P31 to DL-P33) with an extended period to the radio base station. Baseband processing unit 203 and frame control unit 205), and the known signal transmitting unit includes a narrow frequency band (frequency bands BW31 to BW33) included in the known signal frequency band and narrower than the known signal frequency band. The plurality of changed known signals are sequentially transmitted to the communication destination in the extended transmission period (period T2), and each of the changed known signals has a different narrow frequency band, and a plurality of the changed known signals The sum of the narrow frequency bands is equivalent to the known signal frequency band.

  According to a sixth aspect of the present invention, there is provided a wireless communication terminal that transmits a wireless signal including a known signal having a known set value, and the wireless signal that is transmitted from the wireless signal received from the wireless communication terminal. A radio communication method used in a radio base station that calculates a transmission weight applied to a radio signal transmitted to a communication terminal, wherein the radio base station has communication quality of the radio signal received from the radio communication terminal. When determining whether or not the wireless base station is below the predetermined threshold, and narrowing the known signal frequency band, which is the frequency band of the known signal, when the wireless base station determines that the communication quality is lower than the predetermined threshold Transmitting a change instruction for instructing to extend a transmission period of the known signal to the wireless communication terminal; and the wireless communication terminal receives the change instruction And a step in which the wireless communication terminal transmits, to the wireless base station, a modified known signal in which the known signal frequency band is narrowed and a transmission period of the known signal is extended based on the modification instruction. This is the gist.

  According to the features of the present invention, a radio communication system and a radio communication apparatus that can more reliably calculate a transmission weight applied to a radio signal to be transmitted regardless of the position of a communication destination and the frequency band to be allocated 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 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 1 according to the present embodiment. As shown in FIG. 1, the wireless communication system 1 includes a communication network 10, wireless base stations 100A and 100B, and a wireless communication terminal 200. Note that the numbers of radio base stations and radio communication terminals included in the radio communication system 1 are not limited to those shown in FIG.

  The wireless communication system 1 is compliant with mobile WiMAX defined in IEEE 802.16e. That is, in the radio communication system 1, orthogonal frequency division multiplexing (OFDM) and time division duplex (TDD) are used. In the wireless communication system 1, adaptive array control is used.

  The communication network 10 is a wired communication network for connecting the radio base station 100A and the radio base station 100B.

The radio base station 100A receives the uplink radio signal _SUP from the radio communication terminal 200 via the array antenna 101. In addition, the radio base station 100A transmits the downlink radio signal _SDN to the radio communication terminal 200 via the array antenna 101. Note that the radio base station 100B also has the same function as the radio base station 100A.

  In particular, in the present embodiment, the radio base station 100A performs a known signal included in the uplink radio signal SUP (received radio signal) received from the radio communication terminal 200, specifically, a downlink preamble PDL (not shown in FIG. 1). 5 and 6), the transmission weight applied to the downlink radio signal SDN (transmission radio signal) to be transmitted to the radio communication terminal 200 is calculated.

  The radio communication terminal 200 is a portable terminal and receives the downlink radio signal SDN from the radio base station 100A (or 100B). Further, the radio communication terminal 200 transmits an uplink radio signal SUP to the radio base station 100A (or 100B).

(Functional block configuration of wireless communication system)
Next, the functional block configuration of the wireless communication system 1 will be described. Specifically, functional block configurations of the radio base station 100A and the radio communication terminal 200 will be described.

(1) Radio base station 100A
FIG. 2 is a functional block diagram of the radio base station 100A. As shown in FIG. 2, the radio base station 100A includes an array antenna 101, a radio communication unit 103, a baseband processing unit 105, a communication quality determination unit 107, an array control unit 109, a frame control unit 111, and a network connection unit 113. .

  The wireless communication unit 103 is connected to the array antenna 101. The radio communication unit 103 receives the uplink radio signal SUP from the radio communication terminal 200. Further, the radio communication unit 103 transmits a downlink radio signal SDN to the radio communication terminal 200.

  The wireless communication unit 103 includes an LNA, a power amplifier, an up converter, a down converter, and the like.

  The baseband processing unit 105 is connected to the wireless communication unit 103. The baseband processing unit 105 transmits data, specifically, a baseband signal including user data and control data to the wireless communication unit 103, and uses the baseband signal received from the wireless communication unit 103 to transmit user data. Or restore control data. The wireless communication unit 103 executes A / D conversion, Fourier transform (inverse Fourier transform), and the like.

  The communication quality determination unit 107 determines whether the communication quality of the uplink radio signal SUP received from the radio communication terminal 200 is below a predetermined threshold. Specifically, the communication quality determination unit 107 determines whether or not the received signal strength (RSSI) of the uplink radio signal SUP is below a predetermined threshold.

  The array control unit 109 is a known signal that is included in the uplink radio signal SUP received from the radio communication terminal 200 and whose setting values such as amplitude and phase are known, specifically, the uplink preamble PUL and the downlink preamble PDL ( Adaptive array control is executed using FIG. 1 (not shown in FIG. 1, see FIGS. 5 and 6).

Specifically, the array control unit 109 calculates a weight (reception weight) applied to the uplink radio signal SUP using the uplink preamble P _UL . The array control unit 109 performs processing of the received uplink radio signal SUP using the calculated reception weight.

  Further, the array control unit 109 calculates a weight (transmission weight) applied to the downlink radio signal SDN using the downlink preamble PDL included in the uplink radio signal SUP. The array control unit 109 performs processing of the downlink radio signal SDN transmitted to the radio communication terminal 200 using the calculated transmission weight.

  The frame control unit 111 transmits the uplink frame included in the uplink radio signal SUP, for example, the uplink frame UL1 illustrated in FIG. 5 and the downlink frame included in the downlink radio signal SDN, for example, the downlink frame DL1 illustrated in FIG. Execute the control related to the configuration.

  In particular, in the present embodiment, the frame control unit 111 executes control to change the configuration of the uplink frame included in the uplink radio signal SUP according to the communication quality of the uplink radio signal SUP.

Specifically, when the communication quality determination unit 107 determines that the RSSI of the uplink radio signal SUP is below a predetermined threshold, the frame control unit 111 indicates the frequency band of the downlink preamble P _DL , for example, shown in FIG. It is decided to narrow the frequency band BW3 (known signal frequency band). In addition, the frame controller 111 determines to narrow the frequency band BW3 and extend the transmission period (period T1) of the downlink preamble PDL.

  The frame control unit 111 transmits to the wireless communication terminal 200 a change instruction that instructs to change the configuration of the determined downlink preamble PDL. In the present embodiment, the frame control unit 111 constitutes a known signal control unit. A specific method for changing the configuration of the downlink preamble PDL will be described later.

  The network connection unit 113 provides a communication interface for connecting to the communication network 10.

(2) Radio communication terminal 200
FIG. 3 is a functional block diagram of the wireless communication terminal 200. As illustrated in FIG. 3, the wireless communication terminal 200 includes a wireless communication unit 201, a baseband processing unit 203, a frame control unit 205, and a user interface unit 207.

  The radio communication unit 201 receives a downlink radio signal SDN from the radio base station 100A (or 100B, hereinafter the same). In addition, the radio communication unit 201 transmits an uplink radio signal SUP to the radio base station 100A. The wireless communication unit 201 includes an LNA, a power amplifier, an up converter, a down converter, and the like.

  The baseband processing unit 203 is connected to the wireless communication unit 201. The baseband processing unit 203 transmits data, specifically, a baseband signal including user data and control data to the wireless communication unit 201, and uses the baseband signal received from the wireless communication unit 201 to transmit user data. Or restore control data.

  In this embodiment, the baseband processing unit 203 narrows the frequency band (for example, frequency band BW3) of the downlink preamble PDL and changes the instruction to extend the transmission period (period T1) of the downlink preamble PDL. Is received from the radio base station 100A. In the present embodiment, the baseband processing unit 203 constitutes a change instruction receiving unit.

  The frame control unit 205 executes control related to the configuration of the uplink frame included in the uplink radio signal SUP, for example, the uplink frame UL1 shown in FIG. In particular, in the present embodiment, the frame control unit 205 executes control for changing the configuration of the uplink frame based on the change instruction received from the radio base station 100A.

  Specifically, the frame control unit 205 narrows the frequency band of the downlink preamble PDL, for example, the frequency band BW3 shown in FIG. 5 based on the change instruction received from the radio base station 100A, and The transmission period (period T1) is extended. The frame control unit 205 narrows the frequency band and transmits the downlink preamble PDL (change known signal) whose transmission period is extended, specifically, the uplink radio signal SUP including DL-P31 to DL-P33 shown in FIG. Is transmitted to the baseband processing unit 203.

  In the present embodiment, the baseband processing unit 203 and the frame control unit 205 constitute a known signal transmission unit.

  The user interface unit 207 provides a user interface (operation key, display unit, microphone, speaker, etc.) necessary for the user of the wireless communication terminal 200 to use the wireless communication terminal 200.

(Operation of wireless communication system)
Next, the operation of the wireless communication system 1 will be described. Specifically, an operation for changing the configuration of the downlink preamble PDL according to the communication quality (RSSI) of the uplink radio signal SUP will be described.

  FIG. 4 shows an operation flow in which the radio communication system 1 changes the configuration of the downlink preamble PDL according to the RSSI of the uplink radio signal SUP.

  As shown in FIG. 4, in step S <b> 10, the radio base station 100 </ b> A receives an uplink radio signal SUP from the radio communication terminal 200. In step S10, the uplink radio signal SUP includes the uplink frame UL1 shown in FIG.

  As shown in FIG. 5, the uplink frame UL1 includes DL-P1 to DL-P4 as downlink preambles PDL corresponding to the downlink bursts 1 to 4, respectively. DL-P1 to DL-P4 have the same frequency bands as the frequency bands of the downlink bursts 1 to 4, respectively. For example, the DL-P3 frequency band BW3 is the same as the downlink burst 3 frequency band.

  Further, the downlink preamble PDL (DL-P1 to DL-P4) is transmitted over the period T1.

  As illustrated in FIG. 4, in step S20, the radio base station 100A calculates a transmission weight applied to the downlink radio signal SDN using the downlink preamble PDL included in the uplink radio signal SUP. In step S20, the radio base station 100A also calculates a reception weight applied to the uplink radio signal SUP.

  In step S30, the radio base station 100A executes processing of the downlink radio signal SDN transmitted to the radio communication terminal 200 using the calculated transmission weight.

  In step S40, the radio base station 100A acquires the communication quality of the uplink radio signal SUP received from the radio communication terminal 200, specifically, RSSI.

  In step S50, the radio base station 100A determines whether or not the RSSI of the acquired uplink radio signal SUP is lower than a predetermined threshold value.

  When the RSSI of the uplink radio signal SUP is below a predetermined threshold (YES in Step S50), in Step S60, the radio base station 100A determines to change the configuration of the downlink preamble PDL.

  On the other hand, when the RSSI of the uplink radio signal SUP is equal to or greater than the predetermined threshold (NO in step S50), the radio base station 100A repeats the processing from step S10.

  In step S70, the radio base station 100A transmits to the radio communication terminal 200 a change instruction that instructs to change the configuration of the downlink preamble PDL.

  In step S80, the radio communication terminal 200 receives the change instruction from the radio base station 100A, and based on the received change instruction, narrows the frequency band of the downlink preamble PDL and extends the transmission period of the downlink preamble PDL. To do.

  Specifically, as shown in FIG. 6, the radio communication terminal 200 uses DL-P11 to DL-P13, DL- as downlink preamble PDL instead of DL-P1 to DL-P4 (see FIG. 5). An uplink frame UL2 including P21, DL-P22, DL-P31 to DL-P33, and DL-P41 to DL-P43 is transmitted.

  Here, DL-P31 to DL-P33 will be described more specifically as an example. DL-P31 to DL-P33 (change known signals) are included in the DL-P3 shown in FIG. 5, that is, the frequency band BW3 of the downlink burst 3.

  DL-P31 to DL-P33 have a narrower frequency band (narrow frequency band) than the frequency band BW3. Specifically, DL-P31 has a frequency band BW31. Similarly, DL-P32 has a frequency band BW32, and DL-P33 has a frequency band BW33. That is, the frequency bands of DL-P31 to DL-P33 are different from each other. The total frequency band obtained by summing up the frequency bands of DL-P31 to DL-P33 is equivalent to the frequency band BW3.

  DL-P31 to DL-P33 are transmitted from the radio communication terminal 200 to the radio base station 100A in the transmission period (period T2) extended from the period T1 shown in FIG.

  In the present embodiment, the frequency bands BW31 to BW33 are about 1/3 of the frequency band BW3. Further, the period T2 is about three times the period T1.

  As shown in FIG. 4, in step S90, the radio communication terminal 200 transmits an uplink radio signal SUP including an uplink frame UL2. Specifically, the wireless communication terminal 200 wirelessly transmits the downlink preamble PDL whose configuration (frequency band and period) has been changed in the extended transmission period (period T2) based on the change instruction received in step S80. The data is sequentially transmitted to the base station 100A.

(Action / Effect)
According to the radio communication system 1, when it is determined that the RSSI of the uplink radio signal SUP received by the radio base station 100A from the radio communication terminal 200 is below a predetermined threshold, the frequency band of the downlink preamble PDL is narrowed, The transmission period of the downlink preamble PDL is extended.

  When the frequency band of the downlink preamble PDL is narrowed, the reception power density of the uplink radio signal SUP including the downlink preamble PDL increases. For this reason, even when the RSSI of the uplink radio signal SUP received by the radio base station 100A from the radio communication terminal 200 decreases, the downlink preamble PDL can be reliably received. In addition, since the transmission period of the downlink preamble PDL is extended, even when the frequency band of the downlink preamble PDL is narrowed, the radio base station receives the downlink preamble PDL necessary for calculating the transmission weight. be able to.

  In the present embodiment, downlink preamble PDLs whose configurations (frequency bands and periods) are changed, for example, DL-P31 to DL-P33, have different frequency bands. The total frequency band obtained by summing up the frequency bands of DL-P31 to DL-P33 is equivalent to the frequency band BW3. That is, even when the frequency band of DL-P31 to DL-P33 is narrowed in order to increase the power density of the uplink radio signal SUP, the total frequency band is equivalent to the frequency band BW3. The transmission weight applied to SDN can be calculated accurately.

  In the present embodiment, the frequency bands BW31 to BW33 are about 1/3 of the frequency band BW3. Further, the period T2 is about three times the period T1. For this reason, even when the frequency band of DL-P31 to DL-P33 is narrowed, the radio base station 100A ensures the downlink preamble PDL necessary for accurately calculating the transmission weight applied to the downlink radio signal SDN. Can be received.

(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, the downlink preamble PDL may be changed as shown in FIGS. 7 (a) and 7 (b). DL-P31a to DL-P33a shown in FIG. 7 (a) are different in the occupied frequency band compared to DL-P31 to DL-P33 shown in FIG.

  Moreover, DL-P31b-DL-P33b shown in FIG.7 (b) has a different occupation period compared with DL-P31-DL-P33 shown in FIG. That is, DL-P31b to DL-P33b do not necessarily have the same time length.

  In the above-described embodiment, RSSI is used as the communication quality of the uplink radio signal SUP. However, other communication quality parameters such as SINR and CINR may be used.

  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 diagram of the radio base station which concerns on embodiment of this invention. It is a functional block diagram of the radio | wireless communication terminal which concerns on embodiment of this invention. It is a figure which shows the operation | movement flow from which the radio | wireless communications system which concerns on embodiment of this invention changes the structure of a known signal according to the communication quality of a radio signal. It is a figure which shows the structural example (before the structure change of a known signal) of the uplink frame and downlink frame contained in the radio signal which concern on embodiment of this invention. It is a figure which shows the structural example (after the structure change of a known signal) of the uplink frame and downlink frame contained in the radio signal which concern on embodiment of this invention. It is a figure which shows the structural example of the known signal which concerns on the example of a change of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wireless communication system, 10 ... Communication network, 100A, 100B ... Wireless base station, 101 ... Array antenna, 103 ... Wireless communication part, 105 ... Baseband process part, 107 ... Communication quality determination part, 109 ... Array control part, DESCRIPTION OF SYMBOLS 111 ... Frame control part, 113 ... Network connection part, 200 ... Wireless communication terminal, 201 ... Wireless communication part, 203 ... Baseband process part, 205 ... Frame control part, 207 ... User interface part, BW3, BW31-BW33 ... Frequency Band frequency band, DL1 ... downlink frame, P _DL ... downlink preamble, P _UL ... uplink preamble, S _UP ... uplink radio signal, S _DN ... downlink radio signal, T1, T2 ... period period, UL1, UL2 ... uplink Direction frame

Claims (6)

A wireless communication terminal that transmits a wireless signal including a known signal, and a transmission weight applied to the wireless signal transmitted to the wireless communication terminal using the known signal included in the wireless signal received from the wireless communication terminal A wireless communication system comprising:
The radio base station is
A communication quality determination unit that determines whether or not the communication quality of the wireless signal received from the wireless communication terminal is below a predetermined threshold;
When the communication quality determination unit determines that the communication quality is lower than the predetermined threshold, it instructs to narrow the known signal frequency band, which is the frequency band of the known signal, and to extend the transmission period of the known signal. A known signal control unit that transmits a change instruction to the wireless communication terminal,
The wireless communication terminal is
A change instruction receiving unit for receiving the change instruction;
Based on the change instruction received by the change instruction receiving unit, a known signal transmitting unit that transmits the changed known signal in which the known signal frequency band is narrowed and the transmission period of the known signal is extended to the radio base station; A wireless communication system comprising: A wireless communication device that calculates a transmission weight applied to a transmission wireless signal to be transmitted to the communication destination using a known signal that is included in a reception wireless signal received from the communication destination and whose setting value is known,
A communication quality determination unit for determining whether the communication quality of the received radio signal is below a predetermined threshold;
When the communication quality determination unit determines that the communication quality is lower than the predetermined threshold, it instructs to narrow the known signal frequency band, which is the frequency band of the known signal, and to extend the transmission period of the known signal. And a known signal control unit that transmits a change instruction to the communication destination. The known signal control unit sequentially transmits a plurality of modified known signals included in the known signal frequency band and having a narrow frequency band narrower than the known signal frequency band from the communication destination in the extended transmission period. Instruct
The each of the modified known signals is different in the narrow frequency band from each other, and a total frequency band obtained by summing the narrow frequency bands of a plurality of the modified known signals is equivalent to the known signal frequency band. Wireless communication device. The narrow frequency band is 1 / n of the known signal frequency band,
The wireless communication apparatus according to claim 3, wherein the extended transmission period is n times the transmission period before the extension. A wireless communication device that transmits a wireless signal including a known signal to another wireless communication device that is a communication destination,
A change instruction receiving unit for receiving a change instruction for instructing to extend a transmission period of the known signal while narrowing a known signal frequency band that is a frequency band of the known signal;
Based on the change instruction received by the change instruction receiving unit, the known signal frequency band is narrowed, and a radio signal including the changed known signal in which the transmission period of the known signal is extended is transmitted to the other radio communication device. And a known signal transmitter
The known signal transmission unit includes the plurality of changed known signals that are included in the known signal frequency band and have a narrow frequency band narrower than the known signal frequency band in the extended transmission period. In order,
Each of the changed known signals has a different narrow frequency band, and a total frequency band obtained by summing the narrow frequency bands of a plurality of the changed known signals is a wireless communication apparatus equivalent to the known signal frequency band. Applicable to a wireless communication terminal that transmits a wireless signal including a known signal whose set value is known, and a wireless signal that is transmitted to the wireless communication terminal using the known signal included in the wireless signal received from the wireless communication terminal A wireless communication method used in a wireless base station for calculating a transmission weight to be transmitted,
The wireless base station determining whether the communication quality of the wireless signal received from the wireless communication terminal is below a predetermined threshold; and
When the radio base station determines that the communication quality is lower than the predetermined threshold, the radio base station instructs to narrow the known signal frequency band, which is the frequency band of the known signal, and to extend the transmission period of the known signal. Transmitting a change instruction to the wireless communication terminal;
The wireless communication terminal receiving the change instruction;
A radio communication method comprising: a step of transmitting, to the radio base station, a changed known signal in which the known signal frequency band is narrowed and a transmission period of the known signal is extended based on the change instruction. .