JPH11266256A - Radio communication method and radio communication system thereof - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a wireless communication method and a wireless communication system in which an optimal modulation scheme can be appropriately set according to a transmission path. SOLUTION: The communication quality between one radio station and the other radio station is determined, and an optimal modulation scheme among at least two modulation schemes is determined according to the communication quality. Data is transmitted and received between one wireless station and the other wireless station. The communication quality is determined using the signal level and / or error rate of the received inspection signal.
The data between the plurality of wireless stations has a frame structure, and the inspection signal is transmitted during a control signal transmission period or a data transmission period in the frame.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transmitting a continuous data stream such as digital audio data and digital video data between digital audio equipment and digital video equipment and asynchronous data such as a command. The present invention relates to a wireless communication method and a wireless communication system suitable for wireless transmission.

[0002]

2. Description of the Related Art CD (Compact Disc) player, MD
(Mini Disc) Recorder / Player, Digital VT
R, digital camera, DVD (Digital Versatile Di
sc) In recent years, digitalization of audio equipment and video equipment such as players has been advanced. Further, with the spread of personal computers, a system has been developed in which these digital audio devices and digital video devices are connected to a personal computer so that various controls can be performed by the personal computer. As described above, an IEEE (Institute of Electrica) is used as an interface for constructing a system in which each digital audio device or digital audio video device is connected to each other or a personal computer is connected thereto.
l and Electronics Engineers) 1394 is drawing attention.

In IEEE 1394, isochronous (Isochronou)
s) The transfer mode and the asynchronous transfer mode are supported. The isochronous transfer mode is suitable for high-speed transfer of a temporally continuous data stream such as video data and audio data. The asynchronous transfer mode is suitable for transferring various commands and transferring files, for example. in this way,
Since the IEEE 1394 supports an isochronous transfer mode and an asynchronous transfer mode, if the IEEE 1394 is used as an interface, video data and audio data can be transferred between digital audio equipment and digital video equipment, and these can be transferred to a personal computer. To perform various controls and edits with a personal computer.

[0004] However, IEEE 1394 is a wired interface. In order to build the above system with a wired interface, wiring is required,
Also, the cables tend to be cluttered. Also, with a wired interface, it is difficult to connect devices in remote rooms in the home.

Therefore, it is conceivable to connect a digital audio device or digital video device with a personal computer via a wireless LAN (Local Area Network), and perform wireless data communication between these devices. Conventionally, as a wireless LAN, CSMA (Carrier Sense
Multiple Access) method and polling method are known.

However, it is difficult to transfer a data stream such as video data or audio data at high speed using the conventional CSMA system or polling system.

For this reason, an isochronous transfer mode for transferring data streams such as video data and audio data at high speed and an asynchronous transfer mode for transferring asynchronous data such as commands and files are supported.
Development of a wireless LAN that can be used in the same manner as 394 is underway.

[0008]

As a modulation method for performing data communication through a wireless LAN, a conventional GSMK is used.
(Gaussian filtered Minimum Shift Keying) modulation and QPSK (Quadrature Phase Shift Keying) are known. It has been proposed to use a multi-level modulation scheme in order to improve the data transmission rate.

In the multi-level modulation, the amplitude and phase of a carrier wave are simultaneously moved at a plurality of points.
16-level QAM (Quadrature Amplitude Modulation) and 64-level QAM are known. Multi-level modulation is suitable for high-speed transfer of video data and audio data because high-speed transmission is possible in a narrower band.

FIG. 9 shows a signal point arrangement in the case of 16-level QAM modulation. In FIG. 9, the horizontal axis represents the I axis, and the vertical axis represents the Q axis. As shown in FIG.
With value QAM modulation, the amplitude and phase of the carrier are moved to determine the signal constellation.

On the other hand, FIG. 10 shows a signal point arrangement in the case of QPSK modulation. As shown in FIG. 10, in the case of QPSK modulation, the amplitude of the carrier is constant and only the phase is moved.

As described above, the multi-level modulation enables high-speed transmission in a narrow band, but the distance between the signal points is short. Therefore, it is susceptible to noise, and S (Signal) / N (Noise
In an environment with a poor ratio, the occurrence of errors becomes a problem. Therefore, on a transmission line with a good S / N ratio, it is advantageous to perform high-speed transmission using multi-level modulation, but on a transmission line with a poor S / N ratio, a modulation method with a large signal distance is used. It is desirable to deal with errors.

Therefore, it is conceivable to switch the modulation method according to the characteristics of the transmission path. However, in the conventional wireless LAN, the modulation method is fixed, and the modulation method cannot be switched according to the characteristics of the transmission path.

Accordingly, it is an object of the present invention to provide a radio communication method and a radio communication system in which an optimum modulation scheme can be appropriately set according to a transmission path.

[0015]

According to a radio communication system and a transmission method thereof to which the present invention is applied, the communication quality between one radio station and the other radio station is determined, and at least two communication modes are determined in accordance with the communication quality. An optimum modulation method is determined from the modulation methods, and data transmission and reception are performed between one wireless station and the other wireless station using the determined modulation method.

[0016] The communication quality is determined using the signal level and / or error rate of the received test signal.

The data between a plurality of radio stations has a frame structure, and the inspection signal is transmitted during a control signal transmission period or a data transmission period in the frame. Further, the data transmission period is divided into an isochronous region and an asynchronous region, and the inspection signal is sent during the asynchronous transmission period.

As described above, the communication quality between one radio station and the other radio station is determined, and the optimum modulation method among at least two modulation methods is determined according to the communication quality. Since data is transmitted and received between one wireless station and the other wireless station by the system, the S / N of the transmission path
When the ratio is good, data transmission / reception is performed using a modulation method capable of high-speed transmission such as multi-level modulation, and S
When the / N ratio is poor, data transmission / reception is performed using a modulation method relatively resistant to noise such as QPSK modulation.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. The present invention is
As in IEEE 1394, a system is constructed that can transfer a data stream such as video data and audio data and transfer asynchronous data such as a command. FIG. 1 shows an outline of such a wireless network system.

In FIG. 1, WN1, WN2, WN3,
... are wireless nodes which are regarded as communication stations. Each of the wireless nodes WN1, WN2,... Has a digital audio or digital video device AV such as a CD player, an MD recorder / player, a digital VTR, a digital camera, a DVD player, and a television receiver.
1, AV2,... Can be connected. Further, a personal computer may be connected to the wireless nodes WN1, WN2, WN3,. Digital audio or digital video equipment AV1, AV2, connected to the wireless nodes WN1, WN2,.
Are provided with an IEEE 1394 digital interface, and each wireless node WN1, WN
, And digital audio or digital video equipment AV1, AV2,.
394 digital interface.

[0021] WNB is a wireless node to be a control station. Control data is exchanged between the wireless node WNB as the control station and the wireless nodes WN1, WN2,... As the communication stations, and the communication between the wireless nodes WN1, WN2,. Is managed by the wireless node WNB. Between the wireless nodes WN1, WN2,..., Which are communication stations, a temporally continuous data stream (isochronous data) such as digital audio or digital video data or asynchronous data such as a command is wirelessly exchanged. You.

As described above, in this example, a wireless LAN having a star topology is configured as shown in FIG. In a star topology, the central control station CN
, And peripheral terminal stations TN1, TN2,..., And data exchange between the terminal stations TN1, TN2,. A central control station CN corresponds to the wireless node WNB, and the terminal stations TN1, TN2,
.. Correspond to the wireless nodes WN1, WN2,.
It should be noted that the configuration of the wireless LAN is not limited to such a star topology.

Control data, a temporally continuous data stream such as audio data and video data, and asynchronous data such as commands are transmitted between the wireless nodes WN1, WN2,... And the wireless node WNB. These data are transmitted in a frame structure as shown in FIG.

That is, FIG. 3 shows the wireless node WN
1, and the frame structure of data transmitted between WN2,... And between the wireless nodes WNB. As shown in FIG. 3, a control area MA for transmitting management information such as network information is provided at the beginning of one frame. Then, following the control area MA, a stream packet transmission area SPA and an asynchronous transmission area A for performing asynchronous transfer
SYNCA is provided. The stream packet transmission area SPA and the asynchronous transmission area ASYNCA are data transmission areas.

The stream packet transmission area SPA has I
It performs high-speed communication corresponding to the isochronous transfer mode of EEE1394. Stream packet transmission area SPA
Are composed of time slots SL1, SL2,.
The time slots SL1, SL2,... Are units when time-division multiplexing is performed, and slots are provided at predetermined time intervals. In this example, the time slots SL1, SL
The number of 2,... Is, for example, 16. By transmitting a data stream using different time slots SL1, SL2,..., Within the same system,
For example, it is possible to transfer 16 data streams simultaneously.

In the above example, the number of time slots is set to 16, but the number is not limited to this, and the position may be set to an arbitrary position in the frame.

As described above, in the stream packet transmission area SPA, the data stream is transmitted using the time slots SL1, SL2,. At this time, the time slots SL1 and S1 used in one data stream
The number of L2,... Is not constant. For example, the bit rate of an MPEG2 data stream changes depending on pictures, movements, and the like. When the information amount of the data stream increases, the number of time slots SL1, SL2,... Used in one data stream increases, and when the information amount of the data stream decreases, the number of time slots SL1, SL2,. Time slots SL1, SL2 used,
The number of ... decreases.

The stream packet transmission area SPA
In the transmission in the above, control for retransmitting data cannot be performed due to the necessity of high-speed communication. For this reason, an error correction code by block coding is added to deal with errors.

The asynchronous transmission area ASYNCA is based on IEEE.
It corresponds to the asynchronous transfer mode of 1394, and is used to transfer asynchronous data such as a command.
In the transmission in the asynchronous transmission area ASYNCA, control is performed such that an acknowledgment returned from the other party is confirmed and if no acknowledgment is returned from the other party, data is retransmitted so that error-free transmission can be performed. .

Transmission control in the asynchronous transmission area ASYNCA includes, for example, a wireless node W of a central control station.
From the NB, the wireless nodes WN1, WN2 of each communication station,
.. May be controlled by polling operation of..., Or carrier detection may be performed to control the transmission so that transmission requests from other nodes do not collide on the transmission path.

A time slot SL for transmitting a data stream between the wireless nodes WN1, WN2,.
Assignment of 1, SL2,... Is performed by the wireless node WNB, which is a control station.

That is, the wireless node WNB, which has been set as a control station, manages the communication state in the system.
Recognize the time slot currently in use. Also, from the wireless node WNB, which is a control station, management area information is transmitted. According to the management area information, each wireless node WN1, WN2,... Uses which time slot SL1, SL2,. Can be determined.

[0033] The wireless node WNB as a control station
Are the wireless nodes WN1, WN2,
… And polling communication. When there is a data stream transfer request from one of the wireless nodes WN1, WN2,..., The transfer request is sent to the wireless node WNB which has been set as a control station by polling communication. The wireless node WNB as a control station allocates time slots SL1, SL2,... To the wireless nodes WN1, WN2,. The information of the newly allocated time slots SL1, SL2,... Is transmitted. The wireless nodes WN1, WN2, ... that have requested data transfer use the allocated time slots SL1, SL2, ... to transmit a data stream to the other party of the transfer.

Further, in this example, as shown in FIG. 4, the communication quality inspection signal Q
_TEST, an inspection result signal Q_REV, and a modulation information signal M_INFO are sent. Communication quality inspection signal Q_T
The EST is an inspection signal for inspecting the characteristics of the transmission path. The inspection result signal Q_REV is a signal indicating the reception result of the communication quality inspection signal Q_TEST. The modulation information signal M_INFO is transmitted to the communication station WN1,
WN2,... Are signals indicating modulation schemes that can be used.

As described above, in the control area MA, the communication quality inspection signal Q_TEST is transmitted. When communication is performed between the wireless nodes WN1, WN2,... Of each communication terminal using the communication quality inspection signal Q_TEST. Next, the modulation method can be determined.

That is, the wireless nodes WN1, WN2,..., Which are communication stations, transmit a communication quality inspection signal Q_TEST in the control area MA. Communication quality inspection signal Q
_TEST, the wireless nodes WN1, WN2,...
_TEST is received. Then, the communication quality inspection signal Q
_TEST, the wireless nodes WN1, WN2,...
The reception level of _TEST is determined. The wireless nodes WN1, WN2,... Of the communication stations other than the station transmitting the communication quality inspection signal Q_TEST
_TEST signal level, the communication quality inspection signal Q_T
The characteristics of the transmission path to the station transmitting the EST are determined.

For example, the wireless node W in FIG.
A communication quality inspection signal Q_TEST is transmitted from N1. The communication quality inspection signal Q_TEST transmitted from the wireless node WN1 is transmitted to another wireless node WN2,
WN3, WN4,... At this time, the wireless node WN close to the wireless node WN1
2. In the WN6, the reception level of the communication quality inspection signal Q_TEST from the wireless node WN1 is high, but the wireless node WN remote from the wireless node WN1.
4. In WN5, the reception level of the communication quality inspection signal Q_TEST from the wireless node WN1 is low. Therefore, receiving the communication quality inspection signal Q_TEST from the wireless node WN1, the wireless node WN1 and
The quality of the transmission path between the other wireless nodes WN2, WN3,... Can be determined.

Similarly, the wireless nodes WN2, WN
, WN4,..., A communication quality inspection signal Q_TEST is transmitted, and this communication quality inspection signal Q_TEST is received by the other wireless nodes WN2, WN3, WN4,. Wireless nodes WN2, WN3, WN4, ...
And the quality of the transmission path between them.

Each wireless node WN1, WN2, WN
When data is transmitted between 3,..., The modulation scheme is determined according to the quality of the transmission path determined in this way.

That is, for example, it is assumed that QPSK modulation and multi-level modulation can be set. Then, it is assumed that data is transmitted and received between the wireless node WN1 and the wireless node WN2. In this case, the wireless node W
N1 and the wireless node WN2 are close to each other, and the communication quality inspection signal Q_TE from the wireless node WN1 is provided.
It is determined that the reception level of the ST is high and the S / N ratio of the transmission path is good. Therefore, in this case, a multi-level modulation scheme that can obtain a high transmission rate is set.

On the other hand, the wireless node WN1
It is assumed that data is transmitted and received between the wireless node WN4 and the wireless node WN4. In this case, the wireless node WN1
It is separated from the wireless node WN4, the reception level of the communication quality inspection signal Q_TEST from the wireless node WN1 is low, and it is determined that the S / N ratio is poor based on the transmission quality information. Therefore, in this case, the QPSK modulation method is set such that an error does not easily occur even when the S / N ratio is poor.

It should be noted that the reception level of the communication quality inspection signal Q_TEST is used as the inspection result signal Q_REV as the control station WNB.
And a list indicating the quality state of each transmission path may be created in the control station WNB.

In the above-described example, the characteristics of the transmission path are determined from the reception level of the communication quality inspection signal Q_TEST, but may be determined from the error rate of the reception signal. Also, the determination may be made by using two of the level of the received signal and the error rate.

FIG. 5 is a flowchart showing the above-described processing. FIG. 5A shows the operation on the communication station side, and FIG. 5B shows the operation on the control station side.

In FIG. 5, in a control area MA at the start of a frame, one wireless node transmits a communication quality inspection signal Q_TEST, and another wireless node receives this communication quality inspection signal Q_TEST (step). S101). From the reception level of the communication quality inspection signal Q_TEST, the quality of the transmission path can be determined (step S100).

The wireless node on the control station side performs polling communication with each communication station (step S121), and after performing polling communication with each communication station, ends the processing.

The wireless node on the communication station side waits for a polling signal addressed to itself (step S102), and upon receiving the polling, determines whether or not there is transmission data (step S103). The data is transmitted (step S104). Then, it is determined whether or not the frame end has been reached (step S105),
If the frame end has not been reached, step S102
When the frame end has been reached, the processing is terminated.

As described above, in the control area MA, one wireless node transmits the communication quality inspection signal Q_TEST, and the other wireless nodes transmit the communication quality inspection signal Q_TEST.
_TEST, and receives the communication quality inspection signal Q_TES
From the T reception level, the quality of the transmission path is determined.
When transmitting and receiving data between communication stations, available modulation schemes are exchanged according to the quality of the transmission path determined in this way.

FIG. 6 is a flowchart showing a process for determining a modulation method between communication stations when performing communication between wireless nodes W1, WN2,... As described above. FIG. 6A shows the processing of the communication station on the communication requesting side, and FIG. 6B shows the processing of the communication station on the communication partner side.

As shown in FIG. 6, first, the wireless node of one of the communication stations performs the first modulation method (for example, QPS
(K modulation), and based on the quality of the transmission path determined as described above, information on a modulation scheme available at the time of reception is transmitted (step S201).

The communication station on the other end receives a demodulation scheme available at the time of transmission (step S 221), and upon receiving a demodulation scheme available at the time of transmission, transmits a modulation scheme available at the time of reception (step S 221). (S222), the process ends.

After transmitting the available modulation method at the time of reception, the wireless node of one communication station determines whether or not a signal has been received from a communication partner (step S20).
2) When a signal from the communication partner is received, a modulation scheme available to the transmitter is received (step S20).
3), end the process.

As described above, in the system to which the present invention is applied, the wireless nodes WN1 and WN of each communication terminal
When communication is performed between 2,..., The communication quality inspection signal Q_TE
ST is received, and the optimum modulation scheme is determined from the reception level. Thus, when the S / N ratio of the transmission path is good, high-speed data communication can be performed by using multi-level modulation. When the S / N ratio of the transmission path is bad, error transmission using QPSK modulation is possible. The rate can be improved.

In the above example, the communication quality inspection signal Q_TEST is transmitted in the control area at the head of each frame.
As shown in FIG. 7, a modulation quality may be determined by transmitting a communication quality inspection signal in the data transmission area.

FIG. 7 shows an example in which a communication quality check signal is transmitted in the data transmission area to determine the modulation method, and FIG. 7A shows the processing of the wireless node on the first communication station side. FIG. 7B shows the processing of the wireless node on the second communication station side.

As shown in FIGS. 7A and 7B, first, both the wireless node of the first communication station and the second wireless node are set to the first modulation scheme, and the wireless node of the first communication station is set. The node sends a communication quality inspection signal to the wireless node of the second communication station in the data transmission area (Step S301). As the communication quality inspection signal, for example, a PN (Pseudo Noise) code is used.

As shown in FIG. 8B, the wireless node of the second communication station receives this communication quality inspection signal (step S 321), and uses the error rate and the signal strength to obtain the signal.
The quality of the received communication quality inspection signal is evaluated (step 322). Then, in consideration of the quality of the received communication quality inspection signal, a modulation scheme available at the time of reception is transmitted to the first communication station side (step S323).

As shown in FIG. 8A, the wireless node on the first communication station side determines whether or not a signal is transmitted from the second communication station side (step S302). , Obtain a modulation scheme available at the time of transmission, evaluate the reception quality of this signal (step S303), and transmit a modulation scheme available at the time of reception (step S30).
4).

The wireless node side of the second communication station determines whether or not a signal from the first communication station has been received (step S324). If the signal is received, it can be used at the time of transmission. The modulation method is received (step S32).
5) Transmit an acknowledgment signal (step S32)
6), end the process.

In the wireless node on the first communication station side,
It is determined whether there is an acknowledgment signal from the other party (step S305).
This acknowledge signal is received (step S30).
6), end the process.

As described above, when communication is performed between a wireless node and a communication station, an optimum modulation method can be determined by transmitting a communication quality inspection signal in a data transmission area. As described above, the data transmission area is divided into the stream packet transmission area SPA and the asynchronous transmission area ASYNCA. The communication quality detection signal is transmitted, for example, in the asynchronous transmission area ASYNCA.

FIG. 8 shows wireless nodes WN1, WN2,... And WN capable of supporting a plurality of modulation schemes.
The configuration of B will be described. The configuration of the wireless node is basically the same between the wireless node WNB as a control station and the wireless nodes WN1, WN2,... As communication stations.

As shown in FIG. 8, each wireless node W
, And WNB are provided with an IEEE1394 digital interface 11. IEEE
The E1394 digital interface 11 supports time-continuous data (isochronous data) such as digital audio and digital video data, and asynchronous data such as commands.

Each of the wireless nodes WN1, WN
, And WNB are provided with an encoding / decoding unit 12, two modulation / demodulation units 13A and 13B, a high-frequency transmission processing unit 14, a transmission control management unit 15, and a measurement unit 16. I have. Also, two modulation / demodulation units 13A and 13B
Selectors 17 and 18 are provided for switching between.

The encoding / decoding section 12 performs an encoding process on transmission data and a decoding process on reception data. In the transmission of the data stream, the encoding / decoding unit 1
In step 2, an error correction encoding process using a block code is performed on the data stream to be transmitted, and an error correction process is performed on the received data.

The modulation / demodulation sections 13A and 13B perform modulation processing of transmission data and demodulation processing of reception data. The modulation / demodulation sections 13A and 13B use modulation schemes different from each other. Can be For example, the first
The modulation / demodulation unit 13A uses QPSK as a modulation method, and the second modulation / demodulation unit 13B uses a multilevel modulation method, for example, 16-level QAM.

The high-frequency transmission processing section 14 converts the transmission signal to a predetermined frequency, amplifies the power to required power, extracts a signal of a predetermined frequency from the received signal, and converts it to an intermediate frequency signal. Furthermore, the transmission signal is further spread spectrum or OFDM (Orthogonal Frequency Divisio).
n Multiplexing).

The transmission control manager 15 manages data transmission. That is, as described above, in this system, data is transmitted in a frame structure, and a data stream such as digital video data is transmitted using time slots. In asynchronous transmission,
Whether the data has arrived is confirmed by an acknowledgment, and if the data has not arrived, processing such as retransmission is performed. The transmission control management unit 15 performs such data transmission processing.

In this example, two modulation / demodulation units 1
3A and 13B are provided. For example, two modulation schemes are appropriately set by a communication quality inspection signal Q_TEST, an inspection result signal D_MOD, and an inspection return signal Q_ACK of the control area MA at the head of each frame. The processing at this time is performed by the transmission control management unit 15, and these signals are output from the transmission control management area 15. The selectors 17 and 1 receive a control signal from the transmission control management unit 15.
8 is appropriately switched, and the two modulation / demodulation units 13A and 13B are appropriately switched. The transmission control management unit 1
5 is provided with a storage unit for storing a list of modulation schemes, such as which modulation scheme is used for which transmission.

The measuring section 16 evaluates, based on the signal strength and error rate of the received signal, whether communication using the modulation method is possible. The evaluation result is sent to the transmission control management unit 15, and is used when the transmission control management unit 15 determines the modulation scheme.

In the control area MA, the selectors 17 and 18
Is set on the side of a predetermined modulation method, for example, on the side of the modulation / demodulation unit 13A of QPSK modulation. When transmitting a data stream or asynchronous data in the stream packet transmission area SPA or the asynchronous transmission area ASYNCA, the transmission control management unit 15 sets the selectors 17 and 18 as appropriate.

When transmitting data, the data input via the interface 11 is sent to the encoding / decoding unit 12. The encoding / decoding unit 12 encodes the data. The output of the encoding / decoding unit 12 is supplied via a selector 17 to a modulation / demodulation unit 13A for QPSK modulation.
Alternatively, it is supplied to the modulation / demodulation unit 13B of one multi-level modulation.

As described above, in the control area MA, the selector 17 is set on the modulation / demodulation section 13A side, and the stream packet transmission area SPA and the asynchronous transmission area ASYNC
In A, when a data stream or asynchronous data is transmitted, the modulation / demodulation units 13A and 13B are appropriately set.

The data modulated by the modulation / demodulation unit 13A or 13B is supplied to the high-frequency transmission processing unit 14 via the selector 18. This signal is frequency-converted by the high-frequency transmission processing unit 14 to a predetermined transmission frequency, amplified to a required power, and output from the antenna 19.

When receiving data, the antenna 19
Is sent to the high-frequency transmission processing unit 14. The high-frequency transmission processing unit 14 converts the received signal into a predetermined intermediate frequency signal. The output of the high-frequency transmission processing unit 14 is sent to the modulation / demodulation unit 13A or 13B via the selector 18. The modulation / demodulation unit 13A or 13B demodulates the received signal.

The data demodulated by the modulation / demodulation unit 13A or 13B is sent to the encoding / decoding unit 12 via the selector 17. The encoding / decoding unit 12 performs error correction processing and the like, and demodulates the data. The demodulated data is output via the digital interface 11.

In this example, two modulation / demodulation units 13
A and 13B are provided, and a plurality of modulation /
A demodulation unit may be provided. Further, the modulation method of each modulation / demodulation method is not limited to QPSK modulation or multi-level modulation.

[0078]

According to the present invention, the communication quality between one radio station and the other radio station is determined, and the optimum modulation scheme among at least two modulation schemes is determined according to the communication quality. The data is transmitted and received between one radio station and the other radio station in the determined modulation scheme. For this reason, when the S / N ratio of the transmission path is good, data transmission / reception is performed using a modulation method capable of high-speed transmission such as multi-level modulation, and when the S / N ratio of the transmission path is poor. , Data is transmitted and received using a modulation method relatively resistant to noise such as QPSK modulation. Thus, when the S / N ratio of the transmission line is good, high-speed data communication is possible, and when the S / N ratio of the transmission line is bad, the error rate can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of a wireless network system to which the present invention is applied.

FIG. 2 is a schematic diagram used for describing a star-type network system.

FIG. 3 is a schematic diagram used to explain the structure of one frame in a wireless network system.

FIG. 4 is a schematic diagram used for explaining a signal transmitted for determining a modulation scheme.

FIG. 5 is a flowchart used to describe a frame operation.

FIG. 6 is a flowchart used to explain an example of determination of a modulation scheme.

FIG. 7 is a flowchart used to explain another example of determination of a modulation method.

FIG. 8 is a block diagram of an example of a wireless node in a wireless network system to which the present invention has been applied.

FIG. 9 is a vector diagram used for describing 16-level QAM modulation.

FIG. 10 is a vector diagram used for describing QPSK modulation.

[Explanation of symbols]

12: encoding / decoding unit, 13A, 13B: modulation / demodulation unit, 15: transmission control management unit, 16: measurement unit

Claims (16)

[Claims] In a wireless communication method for transmitting and receiving data wirelessly between a plurality of wireless stations, a communication quality between one wireless station and another wireless station is determined, And determining an optimal modulation scheme among at least two modulation schemes, and performing data transmission and reception between the one radio station and the other radio station with the determined modulation scheme. Wireless communication method. 2. The method of claim 1, wherein one of the at least two modulation schemes is a phase modulation and the other is a multi-level modulation.
2. The wireless communication method according to 1. 3. The wireless communication method according to claim 1, wherein said communication quality is determined using a signal level of a received test signal. 4. The wireless communication method according to claim 1, wherein said communication quality is determined using an error rate of a received test signal. 5. The wireless communication method according to claim 1, wherein the communication quality is determined using a signal level of the received test signal and an error rate. 6. The wireless communication method according to claim 1, wherein the data transmitted and received between the wireless stations has a frame structure, and the check signal is transmitted during a transmission period of a control signal in the frame. 7. The wireless communication method according to claim 1, wherein data between the plurality of wireless stations has a frame structure, and the check signal is transmitted during a data transmission period in the frame. 8. The wireless communication method according to claim 7, wherein the data transmission period is divided into an isochronous region and an asynchronous region, and the check signal is sent to the asynchronous region. 9. A wireless communication system in which data transmission / reception between a plurality of wireless stations is performed wirelessly, the wireless station comprising: a modulation / demodulation means for setting at least two modulation schemes; Switching means for switching between modulation and demodulation methods, means for generating a test signal, means for receiving a test signal from another radio station and determining communication quality with the radio communication station, And determining the communication quality between the wireless station and the wireless station, determining an optimal modulation scheme among at least two modulation schemes according to the communication quality, and using the determined modulation scheme, one wireless station and the other A wireless communication system for transmitting / receiving data to / from a wireless station. 10. The wireless communication system according to claim 9, wherein one of the at least two modulation schemes is phase modulation and the other is multi-level modulation. 11. The wireless communication system according to claim 9, wherein said communication quality is determined using a signal level of a received test signal. 12. The wireless communication system according to claim 9, wherein said communication quality is determined using an error rate of a received test signal. 13. The wireless communication system according to claim 9, wherein the communication quality is determined using a signal level of the received test signal and an error rate. 14. The wireless communication system according to claim 9, wherein data transmitted and received between said wireless stations has a frame structure, and said check signal is sent during a transmission period of a control signal in said frame. 15. The wireless communication system according to claim 9, wherein the data transmitted and received between the plurality of wireless stations has a frame structure, and the check signal is transmitted during a data transmission period in the frame. 16. The wireless communication system according to claim 15, wherein said data transmission period is divided into an isochronous region and an asynchronous region, and said check signal is sent to said asynchronous region.