JP2003348635A - Wireless communication system and terminal station - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently search a frequency channel used by its own wireless communication system in a wireless communication system of a distribution control method using a plurality of frequency channels. <P>SOLUTION: The wireless communication system 1 including a plurality of terminal stations 11, 12, 13 and using a plurality of frequency channels is characterized in that the first terminal station 11 transmitting a signal transmits first information associated with the number of frequency channels used by itself superimposed on a particular frequency channel among the frequency channels used by itself. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication system including a plurality of terminal stations capable of performing communication using a plurality of frequency channels, and more particularly, to a radio communication system of a distributed control system in which a terminal station uses itself. The present invention relates to a frequency channel search technique.

[0002]

2. Description of the Related Art In recent years, a plurality of unlicensed low-power wireless communication systems using the 5 GHz band have been proposed and standardized, and wireless systems using the IEEE 802.11a or ARIB (Hi-SWAN standard) of ARIB (Radio Industry Association) have been actually used. Communication systems have been developed.

[0003]

However, the 5.15 GHz band already approved for low-power wireless communication systems is used.
The 5.25 GHz band has only four channels of a frequency band of 20 MHz (the occupied signal frequency band is 18 MHz).
When a large number of wireless communication terminals or a plurality of communication systems exist in the same area, there is a possibility that the throughput may be reduced due to radio wave interference.

[0004] Recently, there has been a movement to further open frequencies in a high frequency band, and a low power wireless communication system using a quasi-millimeter wave band of 25 GHz band or 27 GHz band has been permitted under the Radio Law and standardization has been promoted. . In the past, there has been a movement to open a frequency band limited to other applications by imposing restrictions by electric power or the like.

[0005] According to the frequency allocation plan updated by the Ministry of Internal Affairs and Communications on February 28, 2002, for example, a system for a personal area assuming outdoor Internet access at a hot spot such as a station or a coffee shop is 24.77 GH.
Using a frequency band of 460 MHz from z to 25.23 GH (excluding upper and lower 20 MHz guard bands), 23 radio channels can be arranged at a frequency interval of 20 MHz (an occupied signal frequency band per channel is 18 MHz), Simultaneous transmission of up to three consecutive channels is possible.

Further, from 27.02 GHz to 27.46 GHz
Using a GHz (excluding upper and lower 20 MHz guard bands), a community area assuming a wireless LAN or wireless home link at home or in a factory has a frequency of 20 MHz.
22 wireless channels can be arranged at intervals, and simultaneous transmission of up to six consecutive channels is possible.

The above-mentioned Hi-SWAN standard is a centralized control system in which a base station manages another terminal station. Since the base station adjusts the communication timing of the terminal station, communication efficiency can be increased. It is suitable for communication in an environment where there is a terminal station (for example, outdoor Internet connection at a hot spot).

[0008] On the other hand, a distributed control system represented by the IEEE 802.11a system is a control system in which terminal stations make communication requests with each other and individually adjust the timing between the terminal stations. According to this control method, it is possible to directly communicate between terminal stations (mobile stations) without providing a base station, and a wireless communication system can be easily constructed as compared with the centralized control method. Therefore, it is suitable for construction of a wireless communication system such as a small wireless LAN system.

FIG. 7 is a diagram showing an example of time domain allocation in a wireless communication system using a distributed control system. In the case where the first terminal station on the transmitting side transmits data to the second terminal station on the receiving side, the first terminal station transmits an RTS (Request) which is a data transmission request signal in the area 131.
(st To Send) signal is transmitted to the second terminal station.

When the second terminal station receives the RTS signal normally in the area 135, the second terminal station informs the area 136 of the completion of preparation for data reception by a CTS (Clear To Sen).
d) Transmit the signal. The first terminal station receives C in area 132
When the TS signal is normally received, the data signal is transmitted to the second terminal station in the area 133. The second terminal station is:
When the data signal is normally received in the area 137, the area 1
An acknowledgment (ACK: acknowledgment) signal notifying that the data signal has been normally received at 38 is
Transmit to the first terminal station. The first terminal station is area 1
When the ACK signal is received normally at 34, a series of communication operations between the first terminal station and the second terminal station ends.

It is possible in principle to apply the radio communication system of the distributed control system as shown in FIG. 7 to the above-mentioned radio communication system of the 25 GHz band or the 17 GHz band. In a wireless communication system using the 25 GHz band or the 27 GHz band, up to three or six channels can be used simultaneously, so that high-speed and large-capacity communication can be performed. By making the frequency band used for communication variable, radio wave resources can be used efficiently. By the way, in a communication system in which the frequency band used for such communication is variable, it is necessary for the receiving terminal station at the start of communication to recognize the frequency band used by its own wireless communication system.

In the conventional TDMA distributed control type radio communication system as shown in FIG. 7, one terminal station normally uses one channel for communication, and the number of channels is not so large (for example, as described above). 5GHz
4 channels in the wireless communication system). For this reason, when the terminal station starts communication, it sequentially receives and demodulates a signal including information transmitted from the transmitting side terminal station of its own communication system for each channel, so that its own communication system is used. The search time did not matter much when searching for the channel to be used.

However, in the above-mentioned 25 GHz band or 27 GHz band wireless communication system, since the number of channels is 20 or more, it is difficult to search for a channel used by one's own wireless communication system by a conventional search method. There is a problem that efficiency becomes poor and it takes too much time. Furthermore, when there are a plurality of frequency bands used for communication at the same time, it becomes necessary for the terminal station to recognize information on the frequency band (the number of simultaneously used channels) used by its own wireless communication system.

An object of the present invention is to provide a radio communication system of a distributed control system including a plurality of terminal stations and capable of performing communication using a plurality of frequency channels. Band) can be efficiently searched.

[0015]

According to one aspect of the present invention, there is provided a wireless communication system including a plurality of terminal stations and capable of communicating using a plurality of frequency channels, wherein the first terminal transmits a signal. A wireless communication system is provided, wherein a station transmits first information on the number of frequency channels used by the station on a specific frequency channel among the frequency channels used by the station.

According to another aspect of the present invention, a first terminal station for transmitting a signal, which is suitable for use in a wireless communication system including a plurality of terminal stations and capable of communicating using a plurality of frequency channels. Transmits the first information about the number of frequency channels used by itself on a specific frequency channel among the frequency channels used by itself.

By placing first information on the number of frequency channels used by a specific frequency channel among the frequency channels used by the user, the frequency channel used by the user can be notified. In addition, if transmission is performed only on a specific frequency channel, transmission power can be reduced.

According to another aspect of the present invention, the present invention is suitable for use in a wireless communication system including a plurality of terminal stations and capable of communicating using a plurality of frequency channels. Transmits information on the number of frequency channels to be used to the receiving terminal station, and when receiving a data signal, obtains information on the number of frequency channels used by the transmitting terminal station from the transmitting terminal station transmitting the data signal. Determine a frequency channel to use for data reception based on the information and a frequency channel available to itself.
A terminal station is provided, which transmits information on the determined frequency channel to the transmitting terminal station. According to the above terminal station, one terminal station has a transmission function and a reception function, and these functions can be appropriately used depending on the situation.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing the embodiments of the present invention, the considerations made by the inventor will be briefly described. In a wireless communication system including a plurality of terminal stations, a first terminal station, which is a data transmission side, transmits frequency channel number information (first information) related to the number of frequency channels used by its own wireless communication system, for example, in a data signal. Is added to a "data transmission request (RTS) signal" for notifying that the transmission is performed, and is transmitted to the second terminal station of the transmission partner. The frequency channel number information is transmitted to the second terminal station of the transmission partner, for example, while being included in the preamble signal in the RTS signal. In addition, information (hereinafter, referred to as “frequency channel position information”) on which frequency channel among the frequency channels used by the own wireless communication system to include the preamble signal including the frequency channel information is defined in advance. Keep it.

The frequency channel position information includes, for example, the second information on which frequency channel position of the frequency channel used by itself to transmit the first information, and the position of the self And third information on whether to include the frequency channel used by It is preferable that the frequency channel position information is determined in advance as a protocol and stored in a storage device provided in each terminal station, for example, as a uniform specification in each terminal station that can participate in the wireless communication system.

The first terminal station on the transmitting side, which is currently trying to transmit data, transmits only the specified frequency channel among the frequency channels specified by the frequency channel position information and used by itself. The RTS signal to which the preamble signal is added is carried and sent to the second terminal station on the receiving side.

The second terminal station receives the preamble signal in the RTS signal sent from the first terminal station, and stores the received frequency channel (frequency channel number) and the first information in the preamble signal. Frequency channel number information (usually the number of continuous channels) based on the second information in the predetermined frequency channel position information;
, A frequency channel number (frequency band) that can be used by itself can be obtained.

The second information is, for example, information on which position of a continuous frequency channel included in the first information carries a signal including the first information. Based on the first information and the second information, the second terminal station
The first terminal station makes a proposal as to which frequency channel to use for communication with the second terminal station. The second terminal station adjusts the frequency channel actually used for communication based on the frequency channel proposed by the first terminal station and the frequency channel available to itself (the second terminal station) ( decide. By transmitting this determination to the first terminal station, data communication can be performed using the determined frequency channel.

The second terminal station on the receiving side receives the preamble signal and determines the usable frequency channel by discriminating the additional information by the identification circuit without demodulating the additional information by the demodulation circuit. Can also.

In addition, the third information in the frequency channel position information, for example, information such as “the first terminal station selects and transmits a frequency channel from the high frequency side” is considered. If the search (scanning) procedure for the frequency channel is determined, the second terminal station can simplify the search for the frequency channel in which the first information is included in the preamble signal or the like.

As a method of adding the control information to a preamble signal and identifying the preamble signal by an identification circuit, a method disclosed in JP-A-2001-313623 may be used. This technique will be described later.

Based on the above considerations, embodiments of the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration example of a wireless communication system according to an embodiment of the present invention. The wireless communication system 1 according to an embodiment of the present invention includes, for example, a TDMA (Time Division Multiple Access) configured by a first terminal station 11, a second terminal station 12, and a third terminal station 13. Method) It is a wireless communication system of a distributed control method.

The radio communication system 1 has the above-mentioned 24.7.
This is a wireless communication system capable of simultaneously transmitting up to three continuous channels using frequencies from 7 GHz to 25.23 GHz in 23 wireless channels at a frequency interval of 20 MHz. First terminal station 11 and second terminal station 1
2 means that up to 3 channels can be transmitted and received simultaneously,
The number of channels that can be transmitted and received simultaneously in the third terminal station 13 is limited to two channels.

The number of channels that can be transmitted and received by each terminal station in the above-described wireless communication system is merely an example for convenience of explanation, and for example, a wireless communication system in which all terminal stations can use up to three frequency channels. And may include a terminal station that can use only one channel. Generally, more terminal stations are included.

FIG. 2 is a functional block diagram showing a configuration example of a terminal station constituting a wireless communication system according to an embodiment of the present invention. This will be described with reference to FIG. As shown in FIG. 2, each of the first to third terminal stations 11
To 13, an antenna 21 and an antenna duplexer 22
, An RF / IF receiver 23, an A / D converter 24, a demodulator 25, an information detector 26, a bus control unit 27, a modulator 28, a D / A converter 29, an RF / IF IF transmitter 3
0 and a system control unit 31.

The configuration of each of the terminal stations 11 to 13 is as follows.
As shown in FIG. 2, all have almost the same configuration.
However, there is a case where the specifications of each functional block are partially different due to the difference in the maximum number of transmission / reception channels described above.

Next, the operation of each of the terminal stations 11 to 13 will be described. The received signal input from the transmitting / receiving antenna 21 has its receiving-side path selected by the antenna duplexer 22, and the RF / IF receiver 23 performs amplification of the received signal and frequency conversion to an intermediate frequency (IF) band. Will be The received signal converted to an intermediate frequency (for example, a center frequency of 20 MHz) is converted from an analog format to a digital format by the A / D converter 24, and the received signal is normally demodulated by the demodulator 25. Next, via a bus control unit 27 having a function such as an interface with the outside,
The data is taken into an information processing device PC such as a personal computer (PC) as data (Data).

As described above, the preamble signal including information such as the frame synchronization and the frequency channel can be obtained even if the demodulator 25 does not demodulate the preamble signal.
By applying the method described in Japanese Patent Application Laid-Open No. 2001-313623 to the wireless communication system according to the present embodiment, the information detector 26 determines the frame synchronization and the frequency used by the own system from the preamble periodic pattern and the like. The channel can be determined.

In the example of the method of determining a frequency channel according to the present embodiment, a process of adding first information relating to a frequency channel used by itself to a preamble signal is performed.
The additional processing for adding the first information to the preamble signal includes:
This corresponds to a process of changing the period Tw of the preamble signal according to the frequency band (the number of frequency channels) used by the own system. For example, if the number of frequency channels used by the own radio communication system is “1”, the period of the preamble signal is set to Tw, and if the number of frequency channels used is “2”, the period is set to Tw / 2. If the number of frequency channels to be used is "3", the cycle is set to Tw / 4.

The number of frequency channels included in the first information can be detected based on whether or not the period of the preamble signal matches the preamble pattern stored in the terminal station in advance. In this case, the preamble signal need not be demodulated. Of course, it is also possible to know the number of frequency channels by demodulating the preamble signal without discriminating only the preamble pattern.

Data (Data) output from the personal computer PC or the like is added via the bus control unit 27 to various types of information and converted into a transmission signal format (packet format or the like) used for wireless communication. Is performed by the modulator 28. Next, the transmission signal is converted from a digital signal to an analog signal by the D / A converter 29, and the RF /
In the IF transmitter 30, the transmission signal is amplified and frequency-converted into a high-frequency (RF) signal, and transmitted from the transmitting / receiving antenna 21 to the antenna via the duplexer 22.

The system control section 31 has a function of controlling the system of the entire terminal station, a function of storing and judging frequency channel selection and the like, and a function of controlling power supply to each section (for example, power supply control means (circuit ) 31a). FIG. 3 is a flowchart showing an operation flow of the first terminal station on the transmitting side which transmits a signal, which is a terminal station constituting the wireless communication system according to one embodiment of the present invention. FIG. 4 is a flowchart showing an operation flow in a second terminal station on the receiving side which receives a signal, which is a terminal station constituting the wireless communication system according to one embodiment of the present invention.

The operation of the radio communication system will be described below with reference to FIG. 3 and FIG. 4 focusing on the adjustment method for the frequency channel used by the terminal station. Refer to FIG. 1 as appropriate. First, in a first stage in which negotiations between terminal stations with which communication is to be performed are not established (adjustment is not completed), in step SA11,
The first terminal station on the transmitting side performs carrier sense processing. By performing the carrier sense process, a search is made for a free frequency channel that is not used by another wireless communication device for communication.

In step SA12, the first terminal station 11 estimates the number of frequency channels to be transmitted simultaneously by itself according to the communication capacity of the data signal from the available frequency channels, and allocates the frequency channels. Step SA13
, The first information including at least the number of frequency channels, which is information on frequency channels used for data communication, is converted into information such as a periodic pattern of a preamble signal. In other words, the period Tw of the preamble signal
Is set based on the frequency band (the number of frequency channels) used by the own wireless communication system.

As described above, for example, if the number of frequency channels used by the own radio communication system is 1, the period T of the preamble signal is set to Tw, and if the number of frequency channels is 2, the period T is set to Tw / If the number of frequency channels is 3, the period T is set to Tw / 4.

In step SA14, the preamble signal including the first information on the number of frequency channels
The signal is added to the S signal and transmitted to a second terminal station on the receiving side on a specific frequency channel among the frequency channels used by itself. On the other hand, as shown in FIG. 4, in step SB11, the second terminal station searches for the RTS signal transmitted from the first terminal station, in which the preamble signal is added, and searches for the RTS signal. Perform reception processing.

In step SB12, first information on the number of frequency channels allocated by the first terminal station is obtained based on the period of the received preamble signal and the like. Next, by demodulating the RTS signal, control information necessary for communication such as communication timing is obtained. In step SB12, the frequency channel number information obtained based on the periodic pattern of the preamble signal and the second
Of the received RTS signal and the frequency channel of the received RTS signal, the frequency channel number used by the own radio communication system is obtained, and the searched RTS signal is demodulated. It is possible to avoid useless search processing due to demodulation of the search result, and to shorten the search time.

In step SB13, the assigned frequency channel (number) is compared with the number of frequency channels that can be transmitted / received by itself (the second terminal station 12) at the same time. Judge whether it is good or not. That is, the number of frequency channels transmitted and received by itself (the second terminal station 12) at the same time is the first terminal station 1
When the number of frequency channels is smaller than the number of frequency channels assigned by No. 1, communication cannot be performed using all of the allocated frequency channels. Therefore, the frequency channel used by itself is adjusted from among the allocated frequency channels (the number of channels). (Reduce the number of assignments).

In step SB14, the second terminal station 12 transmits to the first terminal station 11 a CTS signal for notifying that the data reception has been completed, and transmits information on the determined adjusted frequency channel and the like. To inform. Step S
At A15, the first terminal station 11 is switched to the second terminal station 12
, And detects a request for a frequency channel or the like transmitted from the second terminal station 12. Step S
In A16, a frequency channel to be used for communication is determined based on a request from the second terminal station 12 for the frequency channel.

In step SA17, the first terminal station 11 transmits a data signal to the second terminal station 12 using the determined frequency channel. On the other hand, the second terminal station 12 receives the data signal transmitted from the first terminal station 11 in step SB15, and when the reception of the data signal is performed normally, in step SB16, an ACK notifying the fact is given. The signal is transmitted to the first terminal station 11. The first terminal station 11 performs step SA1
At 8, the ACK signal is received, and a series of communication operations is completed.

FIG. 5 is a diagram showing an example of use of frequency channels according to the first example of the wireless communication system according to one embodiment of the present invention. The description will be given with reference to FIGS. 1 to 4 as appropriate. The first terminal station 11 and the second terminal station
Is a frequency channel C as shown in FIG.
Communication is to be started using three consecutive frequency channels from H4 to frequency channel CH6. Here, as described above, it is assumed that the first terminal station 11 and the second terminal station 12 can simultaneously transmit and receive up to three frequency channels.

In the wireless communication system 1 according to the first embodiment, the (control) information including the preamble signal to which the first information on the number of frequency channels used by the own wireless communication system 1 is added is the own wireless communication system. It is specified in advance that the transmission is carried only on the frequency channel of the smallest number (the channel with the lowest center frequency in the frequency band permitted for its own communication system).

The frequency channels used in the radio communication system 1 according to the first embodiment are 23 frequency channels from the frequency channel CH1 to the frequency channel CH23. The frequency channel CH1 is a frequency channel using the lowest frequency band, and the frequency channel CH23 is a frequency channel using the highest frequency band.

When the first terminal station 11 sets a frequency channel to be used by its own radio communication system, the first terminal station 11 uses a number as small as possible (frequency band) as long as there is no problem such as interference with other radio communication systems. The assignment of a frequency channel (lower side) is predetermined as third information, for example, as a standard.

In the example shown in FIG. 5A, frequency channels CH1 to CH3 are allocated to frequency channel CH4 because another radio communication system is in use.
Thereafter, the frequency band of its own wireless communication system is allocated. Note that the first terminal station 11 tries to transmit
Is the first RTS signal RTS1
If the data capacity is large as compared with that of the first terminal station 11, the maximum number of frequency channels (3
Frequency data) using the first data signal DATA1.
It is desirable to transmit. Therefore, the frequency channel C
Three consecutive frequency channels from H4 to frequency channel CH6 are allocated as frequency channels used by the own radio communication system.

Next, the first terminal station 11 transmits, for example, a preamble signal containing the first information to the lowest frequency channel (in this case, frequency channel CH4) of the frequency channels used by itself. The area 51 (frequency channel CH4) based on the provision to transmit
A first RTS signal RT including a preamble signal
S1 is transmitted to the second terminal station 12. Even in the frequency channel allocated to the own radio communication system, the region 52 (frequency channel CH5) and the region 53
In (frequency channel CH6), no signal is transmitted. Thereby, transmission power can be reduced, and as a result, power consumption of modulator 28 and RF / IF transmitter 30 can be reduced. Further, in frequency channels (CH5 and CH6) not transmitting the first information,
The first terminal station 11 can also transmit and receive signals other than control information such as data signals, and in this case, it is possible to increase the efficiency of use of the frequency band.

On the other hand, the second terminal station 12 knows in advance that the control information including the preamble signal is loaded on the lowest-numbered frequency channel among the frequency channels used by its own communication system. Therefore, starting from the frequency channel with the lowest number (frequency channel CH1), sequential scanning is performed while incrementing the frequency channel until the preamble signal of the own radio communication system is captured. At this time, the second terminal station 12
6 detects the period of the preamble signal or the like by a method such as autocorrelation, so that the preamble signal can be detected more quickly than in the case where control information is completely demodulated and frequency band information is detected. .

In the second terminal station 12, information on the period of the detected preamble signal is transmitted to the system control unit 3.
1 analyzes and recognizes the number of frequency channels used by its wireless communication system. That is, when the preamble signal is detected in the four-channel CH4 and the period of the preamble signal is Tw / 4, the first information is placed on the channel of the smallest number used by its own communication system. Therefore, it can be seen that the frequency channels used by the own radio communication system are three consecutive frequency channels from frequency channel CH4 to frequency channel CH6.

When the second terminal station 12 detects a frequency channel that can be used by its own radio communication system, the number of frequency channels that the second terminal station 12 itself can simultaneously transmit and receive and the number of frequency channels transmitted from the first terminal station 11 are determined. The number of frequency channels included in the first information is compared. First terminal station 11
If the number of frequency channels based on the first information transmitted from is equal to or greater than the number of frequency channels that the second terminal station 12 itself can simultaneously transmit and receive, the self (second terminal station 12) A CTS signal carrying information indicating that a frequency channel that can be transmitted and received at the same time is used for communication can be transmitted to the first terminal station 11.

On the other hand, if the number of frequency channels that can be transmitted and received by itself (the second terminal station 12) at the same time is smaller than the number of frequency channels notified from the first terminal station 11, the allocation of the number of frequency channels needs to be reduced. There is. For example, when the request of the other party is three channels from channel CH4 to channel CH6, and the transmission / reception capability of itself is two, the assignment is changed to two channels, channel CH4 and channel CH5. In the first embodiment, the second terminal station 12 is 3
Since frequency channels can be transmitted and received at the same time, the frequency channels remain unchanged (channels CH4 to CH6).
Is transmitted to the first terminal station 11 in the area 66 by carrying information indicating that is used for communication.

The first terminal station 11 transmits the first C
It receives the TS signal, determines the frequency channel to be used for transmitting the first data signal DATA1, and uses the channels CH4 to CH6 to transmit the first data signal DATA1 in the area 55 to the second terminal station 12. Send to The second terminal station 12 transmits the first data signal DAT
A1 is received, and if the first data signal DATA1 can be normally received, the first ACK signal ACK
1 is transmitted to the first terminal station 11. First terminal station 11
Receives the first ACK signal ACK1 in the area 56, and the data communication from the first terminal station 11 to the second terminal station 12 is completed. If the first terminal station 11 cannot receive the first ACK signal ACK1 within a specified time (for example, 4 ms), it retransmits the first data signal DATA1 to the second terminal station 12.

Next, the second terminal station 12 becomes the transmitting side,
The operation when the first terminal station 11 is on the receiving side will be described. The second terminal station 12 which is a terminal station on the transmitting side has 2
A request to transmit the second data signal DATA2 is made using the frequency channels (channels CH4 and CH5). First. In accordance with the above rule, a preamble signal having a period Tw / 2 is added to the second RTS signal RTS2 and transmitted in the area 69. If the negotiation (adjustment) of the frequency channel used for communication has already been established, the same frequency channel as that used in the previous transmission / reception is used unless otherwise hindered. However, when there is some trouble such as interference from another wireless communication system, the transmitting terminal station needs to set the frequency channel used for communication again in the same manner as in the initial state.

The first terminal station 11 which is the terminal station on the receiving side
Receives the second RTS signal RTS2 in the area 57 and detects information about the frequency channel. First terminal station 1
1 can transmit and receive at the same time three frequency channels, and if there is no obstacle to communication for the designated frequency channel, the second CTS signal CT
In S2, information indicating that the same frequency channel (frequency channel CH4 and frequency channel CH5) is used for communication is transmitted.

The second terminal station 12 receives the second CTS signal CTS2 in the area 70, and transmits the second data to the first terminal station 11 in the area 71 (frequency channel CH4 and frequency channel CH5). Transmit the signal DATA2. The first terminal station 11 performs the second
After the reception of the data signal DATA2, and the reception processing is completed normally, the second ACK signal ACK2 is transmitted to the second terminal station 12 in the area 60. The second terminal station 12 transmits a second ACK signal ACK2
And the transmission process from the second terminal station 12 to the first terminal station 11 is completed.

By using the method exemplified above,
Communication capable of efficiently searching for a frequency channel used by its own wireless communication system becomes possible. The terminal station on the transmitting side and the terminal station on the receiving side can perform transmission and reception by switching roles as appropriate.

Next, a radio communication technique according to a second embodiment of the present invention will be described below with reference to the drawings. FIG.
FIG. 8 is a diagram illustrating an example of use of a frequency channel in a wireless communication system according to a second example of an embodiment of the present invention. 1 to 4 are the same as the wireless communication system according to the first embodiment, and will be described with reference to these drawings as appropriate.

In the example of using the frequency channels used by the wireless communication system 1 according to the second embodiment, the frequency channels (frequency bands) used by the wireless communication system 1 are three from the frequency channel CH17 to the frequency channel CH19.
It is a frequency channel. Regarding the frequency channel position information, the transmitting terminal station (the first terminal station 11) which transmits the RTS signal in association with the second information is the frequency of the largest frequency channel number (the highest frequency channel). There is a provision to carry an RTS signal with a preamble signal added only to the channel, and the receiving terminal station (third terminal station 13) that receives the RTS signal in association with the third information is: The difference from the wireless communication system according to the first embodiment is that the preamble signal added to the RTS signal is searched from the highest frequency channel. However, regarding the relation between the period of the preamble signal and the number of frequency channels, the first
It is the same as in the embodiment.

The first terminal station 11 is designed to reduce the search time for the RTS signal to which the preamble signal is added as much as possible, when there is interference with another radio communication system or when the first terminal station 11 uses a frequency band ( A frequency channel having a number as high as possible (high frequency side) is allocated as a frequency channel for transmitting an RTS signal to which a preamble signal is added, unless a frequency channel cannot be continuously secured.

In the example shown in FIG. 6, the first terminal station 1
In order to shorten the search time for searching for the first information from No. 1 unless there is interference with another wireless communication system or when the frequency band to be secured cannot be continuously secured. And assign the highest possible frequency channel. In the wireless communication technology according to the second embodiment, the frequency channel CH22 and the frequency channel CH20 are in use by another wireless communication system,
If the frequency channel CH21 is vacant, but the wireless communication system of its own wants to use the frequency bands of three consecutive frequency channels, the above-mentioned definition of “only the frequency channel of its own is Cannot be secured. "

Therefore, in order to satisfy all the above rules, three frequency channels from frequency channel CH19 to frequency channel CH17 are allocated, and frequency channel CH1
9 with a preamble signal added to the first RTS signal RT
S1 is transmitted in the area 81.

On the other hand, the first to which the preamble signal is added
Of the terminal stations that know in advance (for example, stored in the storage device) that the RTS signal RTS1 of this terminal is to be mounted on the largest frequency channel number among the frequency channels used by its own radio communication system. Third terminal station 1
No. 3 includes a preamble signal (including first information) of its own communication system from the highest-numbered frequency channel (frequency channel CH22 in FIG. 6) in order to shorten the search time of the RTS signal to which the preamble signal is added. )
Are sequentially scanned while the number of frequency channels is decremented until.

The third terminal station 13 can recognize the frequency channel used by its own radio communication system based on the period of the detected preamble signal and the above rules. That is, the third terminal station 13 transmits, for example, the frequency channel C
In H19 (area 91), the first RTS signal to which the preamble signal is added is received, and if the period of the received preamble signal is Tw / 4, the frequency channel CH1
7, frequency channel CH18 and frequency channel CH1
It can be recognized that nine consecutive three frequency channels are frequency channels that can be used by itself.

However, since the number of frequency channels that the third terminal station 13 can transmit and receive simultaneously is two as described above, information indicating that two channels, CH18 and CH19, are used for communication is transmitted to the first CTS. The signal is transmitted in the area 92 on the signal CTS1.

Here, the first CTS signal CTS1 is not a preamble signal for normal frequency synchronization, but an R signal.
By adding a preamble signal having a period Tw / 2 as added to the TS signal and transmitting the preamble signal, the first terminal station 11
Since the number of frequency channels used for transmission can be determined by the information detector 26, the first CTS signal CTS1 can be recognized earlier than demodulation. Therefore, the operation time for modulating the data signal in the modulator 28, which occurs when the number of frequency channels to be transmitted changes, and the RF / IF transmitter 3
The transmission delay of the data signal due to the control time of 0 can be absorbed.

The first terminal station 11 receives the first CTS signal CTS1 in the area 82, recognizes that the frequency channels used for transmission are the frequency channel CH18 and the frequency channel CH19, and in the area 83 3
The first data signal DATA1 is transmitted to the terminal station 13. As shown in FIG. 6A, the first data signal D
After the transmission of the ATA1, the frequency channel CH17 is not used, so that the frequency channel CH17 can be opened to another wireless communication system in order to effectively utilize the radio wave resources. This has the advantage that frequency channels can coexist with other wireless communication systems.

The third terminal station 13 receives the first data signal DATA1 in the area 93, and after the reception processing is completed normally, in the area 94, the first ACK signal AC1 in the area 94.
K1 is transmitted to the first terminal station 11. The first terminal station 11 transmits a first ACK signal ACK1
, And the transmission process from the first terminal station 11 to the third terminal station 13 is completed.

In the subsequent communication phase, the third terminal station 13 sends the first terminal station 11 a frequency channel CH
19 illustrates an operation of transmitting and receiving the second data signal DATA2 using the same method as in the method described above. Second data signal (for example, document data)
DATA2 has an example in which the data capacity is smaller than that of the first data signal (for example, moving image data) DATA1, and in this case, if only one frequency channel is used for communication as shown in FIG. It is enough.

According to the above method, communication capable of efficiently searching for a frequency channel used by the own radio communication system becomes possible. As described above, the RTS signal to which the preamble signal including the information of the frequency channel is added may be added to the channel with the largest number.

As described above, according to the radio communication system of the present embodiment, in a radio communication system capable of simultaneously using a plurality of frequency channels, the receiving terminal station uses the channel and frequency band used by its own radio communication system. Can be easily detected.

Further, the terminal station in the radio communication system according to the present embodiment can search for the first information on the number of frequency channels more efficiently than the method of simply searching for frequency channels, so that the search time can be reduced. Is possible. Further, the terminal station according to the present embodiment transmits the first information on the number of frequency channels in all frequency channels by limiting the frequency channels for transmitting the RTS signal, the CTS signal, and the ACK signal to specific channels. Compared with the method, the transmission energy can be reduced, and the power can be saved.

Further, the terminal station according to the present embodiment transmits or receives a signal different from the first information in an empty frequency channel by limiting the frequency channel used for transmitting the first information. This makes it possible to use frequency channels efficiently in a communication system. As described above, the present invention has been described according to the embodiments, but the present invention is not limited to these. It will be apparent to those skilled in the art that various other modifications, improvements, and combinations are possible.

[0077]

As described above, according to the wireless communication system of the present invention, in a wireless communication system capable of simultaneously using a plurality of frequency channels, the receiving terminal uses its own wireless communication system. Channels and frequency bands can be easily recognized. Further, the terminal station of the present invention can shorten the search time as compared with the method of searching channels in order. Further, transmission energy can be reduced as compared with the case where information on the number of frequency channels is transmitted in all frequency channels. In addition, the limited use of the frequency channels enables effective use of the unused frequency channels.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a wireless communication system according to an embodiment of the present invention.

FIG. 2 is a functional block diagram showing a configuration example of a terminal station configuring a wireless communication system according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a flow of an operation example of a transmitting-side terminal station configuring the wireless communication system according to the embodiment of the present invention;

FIG. 4 is a flowchart illustrating a flow of an operation example of a terminal station on the receiving side that configures the wireless communication system according to the embodiment of the present invention;

FIG. 5 is a diagram illustrating an example of using a frequency channel in a wireless communication system according to a first example of an embodiment of the present invention.

FIG. 6 is a diagram illustrating an example of using frequency channels in a wireless communication system according to a second example of an embodiment of the present invention.

FIG. 7 is a diagram illustrating an example of use of a frequency channel in a general distributed control wireless communication system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wireless communication system, 11, 12, 13 ... First to third terminal stations, 21 ... Transmission / reception antenna, 22 ... Antenna duplexer, 23 ... RF / IF receiver, 24 ... A / D converter, 25 demodulator, 26 information detector, 27 bus control unit, 28 modulator, 29 D / A converter, 30 RF
/ IF transmitter, 31 ... System control unit, 51, 65, 8
1, 91... Area of the first data transmission request signal, 52, 5
3 ... blank area, 54, 66, 82, 92 ... first data transmission permission signal area, 55, 67, 83, 93 ... first data signal area, 56, 68, 84, 94 ... first Data signal reception completion signal area, 57, 69 ... second data transmission request signal area, 58, 70 ... second data transmission permission signal area, 59, 71 ... second data signal area, 60, 72... Area of the second data signal reception completion signal

Claims (20)

[Claims] 1. A wireless communication system including a plurality of terminal stations and capable of communicating using a plurality of frequency channels, wherein a first terminal station transmitting a signal has a first number of frequency channels used by the first terminal station. And transmitting the information on a specific frequency channel among the frequency channels used by the user. 2. The method according to claim 1, wherein the specific frequency channel is predetermined frequency channel position information, and the first frequency channel is used for transmitting the first information on which frequency channel among the frequency channels used by the specific frequency channel. 2. The radio communication system according to claim 1, wherein the radio communication system is determined based on frequency channel position information including the information of the second channel. 3. The wireless communication system according to claim 2, wherein said frequency channel position information further includes third information on which position in a free frequency channel includes a frequency channel used by itself. 4. The first information is a preamble signal in a data transmission request signal transmitted by a first terminal station on a signal transmitting side, and is included in a preamble signal having a period that differs according to the number of frequency channels. The wireless communication system according to any one of claims 1 to 3, wherein: 5. The second information includes information as to whether only the low frequency side or the high frequency side of the frequency band used by the own radio communication system is used as the specific frequency channel. The wireless communication system according to claim 2, wherein: 6. The third information includes a frequency channel actually used by the own wireless communication system from a lower frequency side or a higher frequency side of a frequency band usable by the own wireless communication system. 4. The wireless communication system according to claim 3, further comprising information on whether to select. 7. A radio communication system including a plurality of terminal stations and suitable for use in a wireless communication system capable of communicating using a plurality of frequency channels, wherein a first terminal station transmitting a signal uses a frequency channel used by the first terminal station. A first terminal station which transmits first information on numbers on a specific frequency channel among frequency channels used by itself. 8. The method according to claim 7, wherein the first information is transmitted in a data transmission request signal for notifying that a data signal is transmitted on the specific frequency channel. Terminal station. 9. The first terminal station according to claim 8, wherein no signal is transmitted in a frequency channel of said own frequency channel which does not transmit said data transmission / reception request signal. 10. The first transmission method according to claim 8, wherein a signal other than the data transmission / reception request signal is transmitted in a frequency channel of the frequency channel not used for transmitting the data transmission / reception request signal. Terminal station. 11. The specific frequency channel is predetermined frequency channel position information, and the frequency channel position information related to which one of the frequency channels used by itself to transmit the first information. The first terminal station according to any one of claims 7 to 10, wherein the first terminal station is determined based on frequency channel position information including the second information. 12. The radio communication system according to claim 11, wherein said frequency channel position information further includes third information on which position in a free frequency channel includes a frequency channel used by itself. 13. The second information is information on whether the specific frequency channel is only a low-frequency side or a high-frequency side of a frequency band used by its own wireless communication system. The first terminal station according to claim 11, wherein: 14. The third information includes a frequency channel actually used by the radio communication system from a low frequency side or a high frequency side of a frequency band usable by the radio communication system. 13. The first terminal station according to claim 12, wherein the first terminal station is information on whether to select. 15. A second terminal station that receives and responds to the first information according to claim 7, wherein the second terminal station receives the data transmission request signal carried on the specific frequency channel, and receives the first information. A second terminal station comprising an information detector for identifying the first information on a frequency channel used by a communication system. 16. A second terminal station responsive to the first information according to claim 7, wherein the second terminal station is based on predetermined information on which position in the free frequency channel includes the frequency channel used by the terminal. A second terminal station that sequentially searches from a frequency channel of the lowest frequency band or a closer frequency band of the highest frequency band until the first information is received. 17. The second terminal station according to claim 15, wherein: a frequency channel used by its own radio communication system identified from said data transmission request signal; and a frequency usable by its own terminal station. It adjusts the frequency channel used by its own wireless communication system from the channel, and transmits the result of the adjustment on a data transmission permission signal for notifying that the transmission of the data signal on the specific frequency channel is permitted. A second terminal station, characterized in that: 18. The first terminal station responding to a data transmission permission signal of the second terminal station, wherein the first terminal station receives the data transmission permission signal, identifies the frequency channel after the adjustment, and The first terminal station according to claim 17, wherein the first terminal station transmits the data signal using the identified adjusted frequency channel. 19. A power detecting means for detecting power in each frequency channel, a storing means for storing a power threshold as a criterion for judging whether or not the corresponding frequency channel is used for communication, The terminal station according to any one of claims 1 to 18, further comprising a power comparison unit that compares the power detected by the power detection unit with the power threshold. 20. A wireless communication system including a plurality of terminal stations and capable of performing communication using a plurality of frequency channels, wherein information on the number of frequency channels used by itself when transmitting a data signal is provided. To the receiving terminal station, and when receiving the data signal, obtain information on the number of frequency channels used by the transmitting terminal station from the transmitting terminal station transmitting the data signal, and use the information and the self A terminal station, which determines a frequency channel to be used for data reception based on available frequency channels, and transmits information on the determined frequency channel to the transmitting terminal station.