JP5203406B2 - Wireless communication system and sensing method - Google Patents

Description

  The present invention relates to a wireless communication system and a sensing method.

  In recent years, cellular phones and wireless local area networks (LANs) have become widespread and various services have been provided. In addition, with the provision of services such as moving images, the bandwidth per channel of wireless communication is increasing. For example, in a wireless LAN, the frequency width per channel of IEEE802.11a is 20 MHz, whereas in the new version IEEE 802.11n, the available frequency width per channel is 40 MHz.

  In a wireless communication system, when the bandwidth of a channel is advanced while the assigned frequency band is constant, the number of channels that can be used by the wireless communication system decreases. Therefore, a base station that provides services using the same channel Will increase. As a result, there is a high possibility that interference will occur between service areas (cells). Therefore, it is necessary to control the frequency efficiently in the frequency band assigned to the system. As an example of such control, there is control that separates frequencies used between base stations. However, in a system in which a user can freely install a base station, such as a wireless LAN, it is difficult to exchange and control frequency information used between base stations. Therefore, the base station performs processing such as detecting a signal transmitted from another base station, and when a signal is detected, the base station determines that interference occurs when the detected frequency band is used. If the use is prohibited or detected in the currently used frequency band, frequency control such as changing the used frequency band is performed.

  Further, a cognitive radio system has attracted attention as a means for effectively using the entire frequency. This is a communication method in which the unlicensed system (or secondary system) uses the frequency of the existing license system (or primary system), and the time zone or place where the license system does not use. In this method, operation is performed using the frequency band. In the cognitive radio system, the unlicensed system needs a function of detecting the radio wave transmitted by the radio station of the license system, and recognizes and operates the frequency band where the license system is not operated. If the license system detects radio waves in the channel being used, it is necessary to stop the operation or change the frequency.

  As described above, when the base station detects a signal transmitted from another base station or a radio station of the license system in the channel currently being used, it is necessary to change the frequency in order to continue the operation. is there. Therefore, a frequency that is not operated by another base station or the license system is searched (sensing), and the operation is performed using the frequency. However, when sensing is performed after detecting a signal transmitted by another base station or a radio station of the license system, the operation is stopped during sensing, which may hinder service. In order to solve this problem, there is a method of performing sensing while performing communication between a base station and a terminal (for example, see Non-Patent Document 1). In this method, a spectrum analyzer is provided in a wireless station, and communication and sensing can be performed simultaneously by setting a frequency band other than that used for communication as a sensing target. By this method, it is possible to grasp the frequency band that can be changed in advance, and it is possible to quickly change the frequency even immediately after detecting a signal transmitted from another base station or a radio station of the license system.

Hiroshi Shiba, Munehiro Matsui, Kazunori Akabane, Kazuhiro Uehara, “[Technology Exhibit] Cognitive Radio System with High-Precision Interference Detection / Avoidance Technology”, IEICE Technical Report, vol. 108, no. 172, SR2008-27, pp. 61-66, July 2008

In the future, it is conceivable that the frequency bandwidth that a wireless station can use per channel will further expand. In conventional IEEE802.11a, etc., it was only possible to operate with a fixed frequency bandwidth, but when the usable frequency bandwidth becomes variable, the maximum usable frequency bandwidth is always used between the base station and the terminal. Performing communication has poor frequency efficiency, and it is necessary to increase / decrease the frequency band to be used within the maximum frequency bandwidth according to the amount of communication between the base station and the terminal. However, the frequency bandwidth to be used is not necessarily determined at the start of communication, and the amount of communication changes due to a change in application by the user, and can change even during communication. For this reason, even when communication is performed in a small frequency band, the use frequency band may be increased while continuing the communication. In addition, depending on the performance of the devices in the base station and the terminal, the band of signals that can be transmitted and received may differ between the transmission side and the reception side. For this reason, it is necessary to sense a frequency band that is not used by another wireless station or another system that interferes in parallel while performing communication.
Also, in the above cognitive radio system, other radio stations and other systems that interfere with each other in parallel while communicating are not used in order to change the frequency quickly so as not to hinder the service. It is necessary to sense the frequency band.

  However, in the method of Non-Patent Document 1, sensing can be performed while performing communication. However, since it is necessary to mount a spectrum analyzer in the radio station, problems such as an increase in cost and enlargement of the radio station occur.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a wireless communication system and sensing capable of sensing a wide range of frequency bands while continuing communication without mounting a spectrum analyzer. It is to provide a method.

In order to solve the above-described problem, the present invention is a wireless communication system including a base station device and a terminal device, wherein the terminal device generates a local signal and a local signal generator. an analog demodulation section but for down-converting a radio signal received from the base station device by the local signal generated, utilized communications band is a frequency band of Tei Ru channel used for wireless communication with the base station apparatus and the own terminal device When the local signal of a frequency for receiving the radio signal by the reception band that is part of the monitoring band in the frequency band of said different channel than the channel of the use communication band, so as to generate the local signal generator an instruction unit for instructing the use through the signal of the reception band that is down-converted by the analog demodulation unit Includes a separating portion for separating the band of the signal and the signal before Symbol monitored band, and a signal detecting unit for detecting the presence or absence of use of channels of the monitored band from the signals of separated the monitored zone by the separation unit The base station apparatus can use one of a plurality of channels in the frequency band allocated to the wireless communication system based on a detection result of the presence or absence of use of the channel in the monitoring band by the signal detection unit. Two or more channels having continuous frequency bands are determined as channels used for wireless communication with the terminal device, and wireless signals are transmitted / received to / from the terminal device using the determined channel. It is a communication system.

In order to solve the above-described problem, the present invention is a wireless communication system including a base station device and a terminal device, wherein the base station device generates a local signal and the local signal generator. An analog demodulator that down-converts a radio signal received from the terminal device using a local signal generated by the transmitter, and a plurality of frequency bands assigned to the radio communication system based on a detection result of whether or not the channel is used One channel that can be used or two or more channels having continuous frequency bands are determined as channels used for wireless communication between the base station device and the terminal device, and the wireless communication between the base station device and the terminal device is performed. and use the communication band is a frequency band of the channel used for communications, the channel different from the channel of the available communication bandwidth A local signal of a frequency for receiving the radio signal by the reception band that is part of the monitoring band in the frequency band, and an instruction unit that instructs to generate the local signal generator, which is down-converted by the analog demodulation unit a separation unit for separating a signal of the signal and the previous SL monitored bandwidth of the available communication band from the signal of the reception band, whether from the signals of separated said monitored band of channel utilization of the monitored band by the separation unit A signal detection unit for detecting, wherein the terminal device transmits and receives a radio signal to and from the base station device using the channel used for radio communication with the base station device, and the instruction unit A wireless communication system is characterized in that processing is performed based on a detection result of presence or absence of use of a channel in the monitoring band by a signal detection unit .

Further, the present invention is the above-described wireless communication system, wherein the base station device and the terminal device communicate with each other by a multicarrier radio signal, and the separation unit performs Fourier transform of the signal down-converted by the analog demodulation unit. was carried out, the separating signal of the Fourier transformed result signal of said available communication band from the signal of the reception band obtained in the previous SL monitored band, it is characterized.

  In the wireless communication system described above, the instruction unit may change the reception band according to time so that the use communication band is always included when data is not transmitted / received to the own apparatus. It is characterized by.

  In the wireless communication system described above, the present invention includes a plurality of the local signal generators, wherein the instruction unit determines a plurality of the reception bands including the use communication band, and determines each of the determined plurality of the reception bands. The local signal generator is instructed to generate a local signal having a frequency for receiving the signal by each of the plurality of local signal generators, and the local signal generator generates a local signal used by the analog demodulator for down-conversion. It is characterized by instructing by time to switch to one of the local signals.

Further, the present invention is the above-described wireless communication system, wherein the separation unit includes a first band pass filter that allows the use communication band to pass and a second band pass filter that allows the monitoring band to pass. It is characterized by.

Further, the present invention is in the above-mentioned wireless communication system, the base station apparatus, the usage channel information indicating the information of the channel that is used as determined in the wireless communication with the terminal device, the base station apparatus by radio link It is further characterized by further comprising a channel determination unit that transmits to all established terminal devices.

In order to solve the above-described problem, the present invention is a sensing method used in a radio communication system including a base station apparatus and a terminal apparatus, and the terminal apparatus includes a local signal generator that generates a local signal. and which, prior to SL terminal device, wherein the analog demodulation process for down-converting a radio signal received from the base station apparatus by a local signal the local signal generator caused, the radio between the own terminal device and the base station apparatus and use the communication band is a frequency band of the channel used for communications, the use communication band the channel frequency for receiving the radio signal by the reception band that is part of the monitoring band in the frequency band of a channel different from the In the instruction process for instructing the local signal generator to generate a local signal, and in the analog demodulation process, A separation step of separating the signals of the signal and the previous SL monitored bandwidth of the available communication bandwidth from the down-converted signal of the reception band, from the signal of the monitored band separated in the separation process of the channel of the monitoring band A signal detection process for detecting presence / absence of use, and a plurality of frequency bands assigned to the radio communication system by the base station device based on a detection result of use / non-use of the channel of the monitoring band by the signal detection process 1 or two or more channels having a continuous frequency band are determined as channels used for wireless communication with the terminal device, and wireless signals are transmitted to and from the terminal device using the determined channel. And a process for transmitting and receiving a sensing method.

In order to solve the above-described problem, the present invention is a sensing method used in a radio communication system including a base station apparatus and a terminal apparatus, and the base station apparatus includes a local signal generator that generates a local signal. A process in which the terminal apparatus transmits and receives a radio signal to and from the base station apparatus using a channel used for radio communication with the base station apparatus, and the base station apparatus includes the local signal generator. A plurality of channels in a frequency band allocated to the radio communication system based on an analog demodulation process of down-converting a radio signal received from the terminal device using a local signal generated by the Wireless communication between the base station apparatus and the terminal apparatus using one or two or more channels having continuous frequency bands available from Determined as have channels, use a communication band is a frequency band of the channel used for wireless communication with the terminal apparatus and the base station apparatus, the monitored band in the channel frequency band of said different channel than the available communication band a local signal of a frequency for receiving the radio signal by the reception band that is part of the bets, the local signal and an instruction step of instructing to generate the generator, the analog demodulated signal of the reception band that is down-converted in the process signal detection step of detecting the presence or absence of the use of the use and separation process for separating a signal of the signal before and Symbol monitoring band of the communication band, the signal separated the monitored zone in the separation process of the monitored band channel from If, I have a, the instruction process, the presence or absence of use of the monitored bandwidth of the channel by the signal detecting step Out performs processing based on the result, a sensing method which is characterized in that.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to sense a wide frequency band, utilizing the band which can communicate in a terminal or a base station to the maximum, performing communication, without using a spectrum analyzer. Therefore, in a communication system with a variable communication band, when the amount of communication increases, it is possible to expand the frequency band while continuing communication using the frequency band that has already been detected as free. In addition, when there is a difference in the priority of radio stations, if a radio station with a higher priority starts operating on the same channel, the radio station with a lower priority moves to a frequency that has already detected a vacancy and communicates. It is possible to continue.

1 is a configuration diagram of a radio communication system according to a first embodiment of the present invention. It is a functional block diagram of the base station by the embodiment. FIG. 3 is a functional block diagram of a transmission digital signal processing unit shown in FIG. 2. FIG. 3 is a functional block diagram of a reception digital signal processing unit shown in FIG. 2. It is a block diagram which shows the structure of the terminal by the embodiment. FIG. 6 is a functional block diagram of a transmission digital signal processing unit shown in FIG. 5. FIG. 6 is a functional block diagram of a reception digital signal processing unit shown in FIG. 5. It is a figure which shows the operation start processing flow of the base station by the embodiment. It is a figure which shows the operation start processing flow of the terminal by the embodiment. It is a figure which shows the communication start processing flow of the radio | wireless communications system by the same embodiment. It is a figure which shows the application data transmission / reception flow of the radio | wireless communications system by the embodiment. It is a figure which shows the use availability determination processing flow of the terminal by the embodiment. It is a figure which shows the example of the channel which can use the radio | wireless communications system by the embodiment. It is a figure which shows the example of a setting of the channel information table by the embodiment. It is a figure which shows the example of a setting of the channel information table by the embodiment. It is a figure which shows the example of a setting of the use communication zone | band and monitoring zone | band of a terminal by the embodiment. It is a figure which shows the example of the pass band in BPF of the terminal by the embodiment. It is a figure which shows the example of a setting of the use communication zone | band and monitoring zone | band of a terminal by the embodiment. It is a figure which shows the example of the pass band in BPF of the terminal by the embodiment. It is a figure which shows the example of a setting of the use communication zone | band and monitoring zone | band of a terminal by the embodiment. It is a figure which shows the example of the pass band in BPF of the terminal by the embodiment. It is a block diagram which shows the example of a setting of the utilization communication band of the terminal by the embodiment. It is a figure which shows the example of the pass band in BPF of the terminal by the embodiment. It is a functional block diagram of the reception digital signal processing part of the reception digital signal processing part of the terminal by 2nd Embodiment. FIG. 25 is a functional block diagram of a packet demodulator shown in FIG. 24. It is a figure which shows the use availability determination processing flow by the embodiment. It is a figure which shows the example of a setting of the use communication zone | band and monitoring zone | band of a terminal by the embodiment. It is a figure which shows the example of a setting of the utilization communication band and monitoring band in the FFT calculating part of the terminal by the embodiment. It is a figure which shows the example of a setting of the use communication zone | band and monitoring zone | band of a terminal by the embodiment. It is a figure which shows the example of a setting of the utilization communication band and monitoring band in the FFT calculating part of the terminal by the embodiment. It is a figure which shows the example of a setting of the use communication zone | band and monitoring zone | band of a terminal by the embodiment. It is a figure which shows the example of a setting of the utilization communication band and monitoring band in the FFT calculating part of the terminal by the embodiment. It is a figure which shows the time change of the utilization communication zone | band and monitoring zone | band by the embodiment. It is a block diagram which shows the structure of the terminal by 3rd Embodiment. It is a figure which shows the example of a setting of the use communication zone | band and monitoring zone | band of a terminal by the embodiment. It is a figure which shows the example of a setting of the utilization communication band and monitoring band in the FFT calculating part of the terminal by the embodiment. It is a figure which shows a state when another base station starts operation in the radio | wireless communications system by the embodiment. It is a figure which shows the example of a setting of the channel information table by the embodiment. It is a figure which shows a state when another base station starts operation in FIG. It is a figure which shows the example of a setting of the channel information table by the embodiment. It is a block diagram of the radio | wireless communications system by 4th Embodiment. It is a functional block diagram of the base station by the embodiment. FIG. 43 is a functional block diagram of a reception digital signal processing unit shown in FIG. 42. It is a block diagram which shows the structure of the terminal by the embodiment. FIG. 45 is a functional block diagram of a transmission digital signal processing unit shown in FIG. 44. FIG. 45 is a functional block diagram of a reception digital signal processing unit shown in FIG. 44. It is a figure which shows the application data transmission / reception flow of the radio | wireless communications system by the embodiment. It is a figure which shows the use availability determination processing flow of the terminal by the embodiment. It is a figure which shows the state of the radio | wireless communications system by the same embodiment. It is a figure which shows the example of a setting of the use communication zone | band and monitoring zone | band of a terminal by the embodiment. It is a figure which shows the example of the pass band in BPF of the terminal by the embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First embodiment]
FIG. 1 is a configuration diagram of a radio communication system according to the first embodiment of the present invention. As shown in the figure, the wireless communication system of the present embodiment includes a base station 1 and a terminal 5. In the figure, there are one or more terminals 5 capable of wireless communication with the base station 1 within the service area of the base station 1, and a wireless link is established between the base station 1 and each terminal 5. . Hereinafter, the plurality of terminals 5 are described as a terminal 5-1, a terminal 5-2,.

  In the wireless communication system according to the present embodiment, channels Ch-1, Ch-2,..., Ch-n (n is 2 or more) are used as a plurality of frequency channels (hereinafter, frequency channels are simply referred to as “channels”). Integer). The channel Ch-i is a channel whose channel number is i (i is an integer not less than 1 and not more than n). Here, the channels Ch-1, Ch-2,... To do. The frequency bandwidth of each channel is constant, and the frequency bands of adjacent channel numbers are continuous. The base station 1 and the terminal 5 can communicate using a plurality of frequency channels. For example, when the frequency bandwidth of each channel is 20 MHz and communication is performed between the base station 1 and the terminal 5 at 40 MHz, channels Ch-k and Ch- (k + 1) (k is 1 or more) in which the frequency bands are continuous. (N-1) any one of the following integers) is used.

  FIG. 2 is a block diagram showing an internal configuration of the base station 1 of the present embodiment. The base station 1 includes an antenna 101, a circulator 102, a local signal control unit 103, a local signal generator 104, a transmission digital signal processing unit 105, a digital / analog signal converter (hereinafter referred to as “DAC”) 106, and an analog modulation unit. 107, an analog demodulator 108, an analog-digital signal converter (hereinafter referred to as "ADC") 109, a received digital signal processor 110, a channel information table storage unit 111, a used channel determination unit 112, and an upper layer processing unit 113 is comprised.

  The antenna 101 transmits a radio signal to be transmitted and receives a radio signal. The circulator 102 switches the transmission direction of transmission / reception signals. The local signal control unit 103 receives the local signal information from the use channel determination unit 112 and outputs a local signal control signal for instructing to generate a local signal having a frequency indicated by the local signal information. The local signal generator 104 generates a local signal that is an unmodulated continuous wave of the instructed frequency in accordance with the local signal control signal output from the local signal control unit 103.

  The transmission digital signal processing unit 105 generates a transmission digital signal from the use channel information output from the use channel determination unit 112 and the application data output from the higher layer processing unit 113. The use channel information includes a channel number of a control channel that can be received by all the terminals 5 and a channel number of a communication channel assigned to each terminal 5 individually. The DAC 106 converts the digital signal generated by the transmission digital signal processing unit 105 into an analog signal. The analog modulation unit 107 mixes the local signal generated by the local signal generator 104 with the wireless baseband I / Q signal, which is an analog signal converted by the DAC 106, and converts the mixed signal into a wireless RF (Radio Frequency) signal. .

  The analog demodulator 108 mixes the local signal generated by the local signal generator 104 with the radio RF signal received by the antenna 101 and converts it to a radio baseband I / Q signal. The ADC 109 converts the analog wireless baseband I / Q signal converted by the analog demodulation unit 108 into a digital signal. The reception digital signal processing unit 110 performs processing according to the result of demodulating and decoding the digital signal converted by the ADC 109.

  The channel information table storage unit 111 stores a channel information table. The channel information table indicates the state of each channel. The status includes “available”, “in use”, “unavailable”, and the like. The usage channel determination unit 112 determines the control channel and the usage channel of the terminal 5 based on the state of each frequency channel indicated by the channel information table. The upper layer processing unit 113 executes an upper layer application.

  FIG. 3 is a block diagram illustrating a detailed functional configuration of the transmission digital signal processing unit 105 of the base station 1. The transmission digital signal processing unit 105 includes a use channel information packet generation unit 121, an application packet generation unit 122, a switch 123, and a packet modulation unit 124.

  The usage channel information packet generation unit 121 converts the usage channel information output from the usage channel determination unit 112 into a usage channel information packet. The application packet generation unit 122 converts the application data output from the upper layer processing unit 113 into an application packet. In the process of converting various data (information) into packets, for example, after data is divided into predetermined data lengths, error correction coding, preamble addition, sequence number assignment, information indicating the packet type A process of adding (packet type information) or the like is included.

  The switch 123 switches the output to the packet modulation unit 124 to either the usage channel information packet output from the usage channel information packet generation unit 121 or the application packet output from the application packet generation unit 122. The switch 123 is normally connected to the application packet generation unit 122 side, and switches to the usage channel information packet generation unit 121 side when an instruction is received from the usage channel information packet generation unit 121. The packet modulator 124 converts the use channel information packet or application packet selected by the switch 123 into a radio baseband signal.

  FIG. 4 is a block diagram illustrating a detailed functional configuration of the reception digital signal processing unit 110 of the base station 1. The reception digital signal processing unit 110 includes a packet demodulation unit 131, a packet analysis unit 132, a communication start request packet decoding unit 133, an application packet decoding unit 134, and a signal detection information packet decoding unit 135.

  The packet demodulator 131 converts the radio baseband signal into a packet. The packet analysis unit 132 identifies the type of packet converted by the packet demodulation unit 131 based on the packet type information, and outputs the packet to an appropriate processing unit. The communication start request packet decoding unit 133 decodes the communication start request packet output from the packet analysis unit 132 to acquire communication start request information, and then activates the use channel determination unit 112 to display the acquired communication start request information. introduce. The communication start request packet is a packet for the terminal 5 to request the start of communication, and the communication start request information includes a channel allocated to the terminal 5 such as the upper limit use communication band of the terminal 5, QoS, application type, etc. Contains information for determining. The application packet decoding unit 134 decodes the application packet output from the packet analysis unit 132 to acquire application data, and outputs the application data to the upper layer processing unit 113. The signal detection information packet decoding unit 135 decodes the signal detection information packet output from the packet analysis unit 132 to acquire signal detection information, and is stored in the channel information table storage unit 111 based on the acquired signal detection information. Update the channel information table. The signal detection information indicates a channel in which use failure is detected in the terminal 5. In addition, the signal detection information packet decoding unit 135 activates the use channel determination unit 112.

FIG. 5 is a block diagram showing a configuration of the terminal 5 of the present embodiment.
The terminal 5 includes an antenna 501, a circulator 502, a local signal control unit 503, a local signal generator 504, a transmission digital signal processing unit 505, a DAC 506, an analog modulation unit 507, an analog demodulation unit 508, an ADC 509, a reception digital signal processing unit 510, In addition, an upper layer processing unit 513 is provided.
An antenna 501, a circulator 502, a local signal control unit 503, a local signal generator 504, a DAC 506, an analog modulation unit 507, an analog demodulation unit 508, an ADC 509, and an upper layer processing unit 513 are respectively connected to the antenna 101 of the base station 1 shown in FIG. , Circulator 102, local signal control unit 103, local signal generator 104, DAC 106, analog modulation unit 107, analog demodulation unit 108, ADC 109, and higher layer processing unit 113.

  The transmission digital signal processing unit 505 generates a digital signal for transmission of communication start request information upon activation from the upper layer processing unit 513, application data output from the upper layer processing unit 113, and the reception digital signal processing unit 510. A digital signal for transmission is generated from the signal detection information output from. The reception digital signal processing unit 510 performs processing according to the result of demodulating and decoding the digital signal converted by the ADC 509. The reception digital signal processing unit 510 performs reception control according to the usage channel information when the usage channel information is obtained as a result of demodulation and decoding, and outputs to the upper layer processing unit 513 when the application data is obtained.

  FIG. 6 is a block diagram illustrating a detailed functional configuration of the transmission digital signal processing unit 505 of the terminal 5. The transmission digital signal processing unit 505 includes a communication start request packet generation unit 521, an application packet generation unit 522, a signal detection information packet generation unit 523, a switch 524, and a packet modulation unit 525.

  The communication start request packet generation unit 521 generates a communication start request packet according to an instruction from the upper layer processing unit 513. The application packet generation unit 522 converts the application data output from the upper layer processing unit 513 into an application packet. The signal detection information packet generation unit 523 converts the signal detection information output from the received digital signal processing unit 511 into a signal detection information packet.

  The switch 524 outputs the packet modulation unit 525 to the communication start request packet output from the communication start request packet generation unit 521, the application packet output from the application packet generation unit 522, and the signal detection information packet generation unit 523. Switch to one of the detected signal detection information packets. The switch 524 is normally connected to the application packet generation unit 522 side, and switches when there is an instruction from the communication start request packet generation unit 521 or the signal detection information packet generation unit 523. The packet modulator 525 converts the communication start request packet, application packet, or signal detection information packet selected by the switch 524 into a radio baseband signal.

  FIG. 7 is a block diagram illustrating a detailed functional configuration of the reception digital signal processing unit 510 of the terminal 5. The reception digital signal processing unit 510 includes bandpass filters (hereinafter referred to as “BPF”) 531, 532, a packet demodulation unit 533, a packet analysis unit 534, a use channel information packet decoding unit 535, a reception setting unit 536, an application packet. A decoding unit 537 and a signal detection unit 538 are provided.

  The BPFs 531 and 532 are digital BPFs having a variable pass band, set the pass band according to the pass band information received from the reception setting unit 536, and pass signals in the set pass band. The BPF 531 passes the frequency band (used communication band) of the used channel that is the channel used in the terminal itself, and the BPF 532 passes the frequency band (monitored band) of the monitoring channel that is the sensing target channel. . This pass band is indicated by a frequency based on a DC (direct current) frequency. The packet demodulator 533 converts the radio baseband signal that has passed through the BPF 531 into a packet. The packet analysis unit 534 identifies the packet converted by the packet demodulation unit 533 and transmits the packet to an appropriate processing unit.

  The usage channel information packet decoding unit 535 decodes the usage channel information packet output from the packet analysis unit 534 and outputs the obtained usage channel information to the reception setting unit 536. The reception setting unit 536 determines the usage channel and the monitoring channel based on the communication channel information and control channel information set in the received usage channel information, and information such as the bandwidth that can be received by the local station. The local signal information is output to the signal control unit 503 and the passband information is output to the BPFs 531, 532 to set the passband. In the local signal information, the frequency of the local signal that enables reception of the usage channel and the monitoring channel is set. Further, a pass band corresponding to the use channel is set in the BPF 531, and a frequency band corresponding to the monitoring channel is set in the BPF 532. The application packet decoding unit 537 decodes the application packet output from the packet analysis unit 534, acquires application data, and outputs the application data to the upper layer processing unit 513. The signal detection unit 538 determines whether there is a signal that has passed through the BPF 532.

  Next, processing of the wireless communication system according to the present embodiment will be described. Below, the case where the terminal 5 connects to the Internet via the base station 1 and performs communication will be described.

FIG. 8 shows an operation start process flow of the base station 1.
In the figure, when the base station 1 is activated, it measures the reception levels of all the channels Ch-1 to Ch-n assigned to the wireless communication system, performs signal detection, and determines whether or not it can be used ( In step S11), the determination result of the availability is registered in the channel information table (step S13).

  Specifically, first, the local signal control unit 103 instructs the local signal generator 104 to use the local signal control signal for the center frequency of the channel Ch-1, and the local signal generator 104 uses the local frequency of the instructed frequency. Generate a signal. The analog demodulation unit 108 demodulates the signal received by the antenna 101 into a baseband analog signal using a local signal. The demodulated signal is input to the reception digital signal processing unit 110 via the ADC 109. The packet demodulation unit 131 of the reception digital signal processing unit 110 measures the level of the reception signal input from the ADC 109.

  The packet demodulator 131 determines that the received signal is usable when the reception level of the input received signal is equal to or lower than a predetermined threshold for determining whether or not the channel is used. On the other hand, when the reception level exceeds a predetermined threshold, it is determined that the channel Ch-1 is used for another wireless communication system or the like, that is, cannot be used.

  Subsequently, the base station 1 performs the same processing as in the case of the above-described channel Ch-1 in order for the channels Ch-2,..., Ch-n, and each of the channels Ch-2 to Ch-n can be used. It is judged whether it is or cannot be used. The reception digital signal processing unit 110 writes in the channel information table whether each of the channels Ch-1 to Ch-n is available or unavailable.

  Next, the used channel determination unit 112 determines whether there is an available channel with reference to the channel information table (step S15). If there is no available channel (step S15: NO), the process is terminated and the operation is not performed. If there is an available channel (step S15: YES), one channel to start operation is determined from the available channels (step S17). For example, the channel with the lowest reception level may be determined as the channel for starting operation. The use channel determination unit 112 sets the channel determined in step S17 as a control channel, and transmits a beacon using this control channel (step S19).

  Specifically, the use channel determination unit 112 outputs local signal information in which the center frequency of the control channel is set to the local signal control unit 103, and the local signal control unit 103 uses the local signal control signal to output the center frequency. Instruct the local signal generator 104. At the same time, the use channel determination unit 112 instructs the transmission digital signal processing unit 105 to transmit a beacon, and the transmission digital signal processing unit 105 generates and outputs a beacon signal. The DAC 106 converts the beacon signal output from the transmission digital signal processing unit 105 into an analog signal, and the analog modulation unit 107 converts the beacon signal into a wireless RF signal using the local signal generated by the local signal generator 104. The beacon signal converted into the RF signal is transmitted by the antenna 101.

  Note that the processing from when the antenna 101 receives a radio signal until the digital signal is input to the reception digital signal processing unit 110, the transmission digital signal processing unit 105 transmits the digital signal, and then the antenna 101 transmits the radio signal as a radio signal. Since the processing up to this is the same as described above, the description is omitted below. In the terminal 5, processing from when the antenna 501 receives a radio signal until the digital signal is input to the reception digital signal processing unit 510, and after the transmission digital signal processing unit 505 transmits the digital signal, the antenna 501 Since the processing up to transmission as a radio signal is the same as that of the base station 1, description thereof is omitted below.

  FIG. 9 shows an operation start process flow of the terminal 5. It should be noted that immediately after activation, no setting is made in the BPF 531 of the terminal 5.

When the terminal 5 is activated, it receives a beacon transmitted from the base station 1 (step S21).
Specifically, first, the local signal control unit 503 instructs the local frequency generator 504 by using a local signal control signal for the center frequency of the channel Ch-1, and the local signal generator 504 outputs the local frequency of the instructed frequency. Generate a signal. In addition, the reception setting unit 536 sets the pass band of the BPF 531 to DC to 10 MHz in order to pass one channel. In the reception digital signal processing unit 510, the packet demodulation unit 533 receives the digital signal that has passed through the BPF 531, performs synchronization using the preamble included in the received signal, and then performs demodulation. The packet analysis unit 534 determines whether it is a beacon based on the demodulated signal.
On the other hand, if the reception level of the demodulated baseband analog signal is equal to or lower than a certain value, the received digital signal processing unit 510 cannot demodulate the signal, and therefore it is determined that no beacon is transmitted on channel Ch-1. To do.
The terminal 5 further performs the same processing as in the case of the channel Ch-1 described above in order for the channels Ch-2,..., Ch-n. Thereby, the terminal 5 determines whether or not a beacon is detected for each channel.

  If a beacon can be received on any channel by the above (step S23: YES), the terminal 5 determines a channel to start operation from among the channels that have received the beacon (step S25). That is, using the control channel, authentication and attribution processing is performed for the base station 1 (step S27). As a result, a radio link is established between the base station 1 and the terminal 5. At this time, the frequency of the local signal is set so that the control channel can be transmitted and received. Further, the pass band of the BPF 531 is set to DC to 10 MHz.

FIG. 10 shows a communication start processing flow of the wireless communication system.
First, the terminal 5 activates the communication start request packet generation unit 521 based on the activation trigger from the upper layer processing unit 513 before starting application communication. When the communication start request packet generation unit 521 outputs a switching request to the switch 524 and connects the switch 524 to the communication start request packet generation unit 521 side, the communication start request packet generation unit 521 generates and outputs a communication start request packet. The communication start request packet includes communicable bandwidth information and QoS indicating the maximum frequency bandwidth (the operation speed of the DAC 506 and ADC 509, the characteristics of the devices such as the analog modulation unit 507 and the analog demodulation unit 508) that can be transmitted and received by the terminal itself. The communication start request information including the application type and the like is packetized. The communication start request packet is modulated by the packet modulator 525 and then output to the DAC 506. The terminal 5 transmits a communication start request packet to the base station 1 through the control channel (step S30).

  The communication start request packet received by the base station 1 is demodulated by the packet demodulator 131 and determined by the packet analyzer 132 as a communication start request packet. When the communication start request packet decoding unit 133 decodes the communication start request packet output from the packet analysis unit 132, the communication start request packet decoding unit 133 activates the use channel determination unit 112 and transmits the communication start request information obtained by the decoding to the use channel determination unit 112. Output (step S31). The use channel determination unit 112 determines the frequency bandwidth used for transmission / reception of the application data packet based on the communicable bandwidth information indicated by the communication start request information, QoS, the type of application, and the like. The use channel determination unit 112 refers to the channel information table, and uses channels having consecutive channel numbers that can be used by the number of channels having the determined frequency bandwidth to transmit and receive packets to and from the terminal 5. The communication channel is determined (step S33). The use channel determination unit 112 stores in the channel information table that the channel determined as the communication channel is being used. Further, the communication start request information received from the terminal 5 is stored in a storage unit provided therein.

  The use channel determination unit 112 outputs the use channel information in which the communication channel information and the control channel information are set to the transmission digital signal processing unit 105. The communication channel information indicates the channel number of the assigned channel, and the control channel information indicates the channel number of the control channel. When the switch 123 is connected to the use channel information packet generation unit 121 side, the use channel information packet generation unit 121 of the transmission digital signal processing unit 105 connects the received use channel information and the communication channel with the terminal 5 scheduled to use the communication channel. A use channel information packet storing the identification information is generated and output. The usage channel information packet is modulated by the packet modulation unit 124 and then output to the DAC 106. The base station 1 transmits the usage channel information packet to all terminals 5 using the control channel.

  At the same time, the usage channel determination unit 112 changes the frequency of the local signal so that the packet can be transmitted using the usage channel. That is, the use channel determination unit 112 sets the center frequency of the use channel that combines the communication channel of the terminal 5 and the control channel in the local signal information, and outputs the local signal information to the local signal control unit 103. The local signal generator 104 generates a local signal having a frequency indicated by the local signal control signal received from the local signal control unit 103 (step S35).

  Each terminal 5 receives the usage channel information packet transmitted from the base station 1 through the control channel (step S37). In each terminal 5, the use channel information packet converted into the digital signal passes through the BPF 531 of the reception digital signal processing unit 510 and is output to the packet demodulation unit 533. When the packet demodulator 533 decodes the input usage channel information packet, and the packet analysis unit 534 analyzes the demodulated packet and determines that it is a usage channel information packet from the packet type, the usage channel information packet decoding unit Output to 535. The usage channel information packet decoding unit 535 outputs the usage channel information obtained by decoding the usage channel information packet to the reception setting unit 536.

The reception setting unit 536 sets the use communication band and the monitoring band of the own terminal based on the use channel information obtained by decoding. The used communication band is the communication band of the use channel of the own terminal, and the monitoring band is the communication band of the monitoring channel of the own terminal.
For example, the use channel information in which the terminal 5-1 is set as the destination from the base station 1, the channels Ch-3 and Ch-4 are set in the communication channel information, and the channel Ch-4 is set in the control channel information is controlled. Suppose that it was transmitted by the channel. In this case, the channels used by the terminal 5-1 as the destination are channels Ch-3 and Ch-4 that combine the channel used as the communication channel and the channel used as the control channel, and the channels used by the terminals 5 other than the terminal 5-1 Is the channel Ch-4 used for the control channel.
In addition, the communication possible band of the own terminal centering on the use communication band is set as the reception band, and the communication band corresponding to the communication channel and the control channel indicated by the use channel information (including the communication band of other terminals is included) from this reception band. The bandwidth excluding) is the monitoring bandwidth.

  When the reception setting unit 536 sets the use communication band and the monitoring band of the terminal itself, the reception setting unit 536 subsequently changes the frequency of the local signal. The reception setting unit 536 outputs the local signal information in which the center frequency of the channel used by the terminal is set to the local signal control unit 503, and the local signal control unit 503 outputs the local signal having the center frequency set in the local signal information. A local signal control signal is output for generation. The local signal generator 504 generates a local signal having a frequency designated by the local signal control signal.

Further, the reception setting unit 536 changes the passband of the BPFs 531, 532. At this time, the BPF 531 connected to the packet demodulating unit 533 following the application packet decoding unit 537 sets the frequency band of the usage channel as a pass band, and the BPF 532 connected to the signal detection unit 538 has a channel other than the usage channel. The frequency band of the channel is set as the pass band (step S39).
Thereafter, the base station 1 transmits the application data packet to the terminal 5-1, and the terminal 5-1 also transmits the application data packet to the base station 1.

FIG. 11 shows an application data transmission / reception flow of the wireless communication system. Here, an example in which an application data packet is transmitted from the base station 1 to the terminal 5 is shown.
The application packet generation unit 122 of the base station 1 generates an application packet from the application data output from the higher layer processing unit 113, and the packet modulation unit 124 modulates the generated application packet and outputs it to the DAC 106. The application packet modulated into the RF signal is transmitted using the communication channel of the terminal 5 that is the destination (step S41).

  The packet demodulator 533 of the terminal 5 demodulates the packet passed by the BPF 531, and the packet analyzer 534 outputs this packet to the application packet decoder 537 because the demodulated packet is an application packet. The application packet decoding unit 537 decodes the demodulated application packet, and outputs the obtained application packet to the upper layer processing unit 513 (step S43). When the transmission / reception of the application packet is not yet completed between the base station 1 and the terminal 5 (step S45: NO), the processing from step S41 is repeated, and the transmission / reception of the application packet is completed (step S45: YES). ) To complete the process.

  At the same time as the processing in FIG. 11, the terminal 5 determines whether or not the monitoring channel that is a sensing target can be used.

FIG. 12 shows a process flow for determining whether or not to use the terminal 5 by observing the signal level.
The BPF 532 of the terminal 5 passes the signal in the frequency band to be sensed, and the signal detection unit 538 measures the signal level of the signal that has passed through the BPF 532 (step S51) and compares it with a predetermined threshold (step S53). If the signal levels of all channels are less than the threshold value (step S53: NO), the process is terminated. On the other hand, when the signal level exceeds the threshold value in at least one channel (step S53: YES), the signal detection unit 538 determines that a signal transmitted from another base station 1 or another system exists in the channel, It is determined that the channel of the frequency band cannot be used. The signal detection unit 538 outputs the signal detection information in which the channel number determined to be unavailable is set to the signal detection information packet generation unit 523. When the signal detection information packet generation unit 523 outputs a switching request to the switch 524 and connects the switch 524 to the signal detection information packet generation unit 523 side, the signal detection information packet generation unit 523 generates a signal detection information packet from the input signal detection information. Output to. The signal detection information packet is transmitted to the base station 1 using the control channel (step S55).

  The base station 1 receives the signal detection information packet through the control channel (step S57). The packet demodulation unit 131 of the base station 1 demodulates the received packet, and the packet analysis unit 132 outputs the demodulated packet to the signal detection information packet decoding unit 135 because the demodulated packet is a signal detection information packet. When the signal detection information packet decoding unit 135 obtains signal detection information by decoding the signal detection information packet, the channel of the channel number set in the obtained signal detection information is used by another base station 1 or another system. It is determined that it is unusable. The signal detection information packet decoding unit 135 reads the current state of the channel determined to be unusable from the channel information table, and then writes and updates that the channel is unusable in the channel information table (step S59).

  Further, the signal detection information packet decoding unit 135 ends the process if the channel state acquired before writing “unusable” is not in use (step S61: NO), and if it is in use (step S61). : YES), the process from step S33 in FIG. 10 is performed, and a new use channel is assigned to the terminal 5 that has used this channel (step S63). If finished, return to the beginning and repeat this process.

  Communication when the terminals 5-1 and 5-2 exist in the service area of the base station 1 and the terminals 5-1 and 5-2 connect to the Internet via the base station 1 to perform browsing. A processing example is shown. The base station 1 switches the communication destination terminal 5 by time division.

  FIG. 13 is a diagram illustrating channels that can be used by the wireless communication system. As shown in the figure, it is assumed that there are eight channels, Ch-1 to Ch-8, that can be used by the wireless communication system, and each has a frequency band of 20 MHz.

  Further, it is assumed that the base station 1 and the terminal 5-1 can communicate in a band up to 80 MHz and the terminal 5-2 in a band up to 100 MHz depending on the performance of various analog devices, DACs, ADCs, and the like. In addition, the channel availability determination in the base station 1 and the terminal 5 is performed by observing the signal level. In the base station 1 and the terminal 5, −60 dBm is set as the threshold value.

  Then, according to the processing of FIG. 8, when the base station 1 is activated, it measures the received power level of all channels, determines that it can be used on all channels, and starts operation on the channel Ch-5 from among them. To do. 9, the terminal 5-1 and the terminal 5-2 try to receive a beacon on each channel in order from the channel Ch-1, and succeed in receiving the beacon on the channel Ch-5. As shown in FIG. 1, the terminals 5-1 and 5-2 belong to the base station 1. At this time, the local signal is set to 5.26 GHz so that the signal can be transmitted and received by Ch-5. Further, the pass band of the BPF 531 is set to DC to 10 MHz so as to pass the signal of the CH-5 band.

  FIG. 14 is a diagram showing the setting contents of the channel information table when the base station 1 determines that it can be used on all channels. There are no other base stations 1 or radio stations of other systems in the vicinity, and as shown in the figure, the channel information tables of the base station 1 and the terminal 5 are “available” for all eight channels. is there. Base station 1 has selected channel Ch-5 as the control channel.

First, a procedure in which the terminal 5-1 connects to the Internet via the base station 1 and performs browsing will be described.
First, the user of the terminal 5-1 inputs an instruction for trying to connect to the Internet via the base station 1. The terminal 5-1 recognizes this operation in the upper layer processing unit 513, and transmits a communication start packet to the base station 1 (FIG. 10, step S30). In the communication start request packet, a bandwidth and QoS in which the terminal 5-1 can communicate are stored. QoS is a bandwidth and priority required for communication. For example, when a terminal performs moving image communication, information of 6 Mbit / s is stored as a required bandwidth. In this operation example, it is assumed that only information indicating that the communicable band of the terminal 5-1 is 80 MHz is stored in the communication start request packet.

  When the base station 1 receives the communication start request packet from the terminal 5-1 (FIG. 10, step S31) and acquires the communication start request information, the communicable bandwidth information in the communication start request information, the channel information table, The communication channel of the terminal 5-1 is determined based on the above (FIG. 10, step S33), and the use channel information packet is transmitted to all the terminals 5 (FIG. 10, step S35). Here, two channels (40 MHz) of channels Ch-4 and Ch-5 are allocated to the terminal 5-1, and an application packet is transmitted. The base station 1 includes communication channel information in which channels Ch-4 and Ch-5 are set, control channel information in which the channel Ch-5 is set, and identification information of the terminal 5-1 that is scheduled to use the communication channel. The use channel information packet is generated from the use channel information storing the destination information in which the destination information is set, and transmitted to all the terminals 5 using the channel Ch-5 that is the control channel. At the same time, the frequency of the local signal is set to 5.25 GHz which is the center frequency of the frequency band (5.23 GHz to 5.27 GHz) of the entire channels Ch-4 and Ch-5.

  FIG. 15 is a diagram showing the setting contents of the channel information table of the base station 1 after assigning a channel to the terminal 5-1. As shown in the figure, channels Ch-4 and Ch-5 are updated during use.

  All the terminals 5 receive the use channel information packet through CH-5. The terminal 5-1 receives the usage channel information packet (FIG. 10, step S 37), acquires the usage channel information, transmits the application data to the own station, and the channels Ch- 4 and Ch- 5. Recognizes that the application packet reception channel and channel Ch-5 is the control channel. The terminal 5-1 uses the frequency bands of the channels Ch-4 and Ch-5 as the use communication band.

  Here, since the communicable band is 80 MHz, the terminal 5-1 can perform communication using up to the maximum number of channels 4. Therefore, the terminal 5-1 does not change the frequency of the local signal for receiving the channels Ch-4 and Ch-5, that is, the channels Ch-4 and Ch-5, including the channels Ch-4 and Ch-5. Channels Ch-3 to Ch-6 for four channels can be received. Therefore, the reception setting unit 536 of the terminal 5-1 determines the channels Ch-3 and Ch-6 obtained by removing the channels used by the terminal 1 from the receivable channels Ch-3 to Ch-6 as the monitoring channels. To do. As described above, the terminal 5-1 receives the application packet through the channels Ch-4 and Ch-5, and the other base station 1 and the other system transmit signals using the channels Ch-3 and Ch-6. Decide to monitor whether or not. The setting of the target band at this time is shown in FIG.

  FIG. 16 is a diagram showing the communication bandwidth used and the monitoring bandwidth of the terminal 5-1. In the figure, the frequency of the local signal is set to the center frequency 5.25 GHz of the channels Ch-4 and Ch-5, which are used channels. The reception setting unit 536 of the terminal 5-1 prepares and sets the BPF 531 so as to receive signals transmitted on the channels Ch-4 and Ch-5, and uses the BPF 532 on the channels Ch-3 and Ch-6. Preparation is made so that the detected signal can be detected (step S39 in FIG. 10). FIG. 17 shows the settings of BPF 531 and BPF 532 at this time.

  FIG. 17 is a diagram illustrating the BPF passband of the terminal 5-1. This figure shows a frequency with DC as a reference frequency. In the figure, since the local signal DC to 20 MHz corresponds to the channels Ch-4 and Ch-5, the pass band of the BPF 531 is set to DC to 20 MHz. Also, since 20 MHz to 40 MHz correspond to the channels Ch-3 and Ch-6, the pass band of the BPF 532 is set to 20 MHz to 40 MHz.

  Similarly, the terminal 5-2 receives the usage channel information packet (FIG. 10, step S37), acquires the usage channel information, and the channels Ch-4 and Ch-5 are addressed to other stations (terminal 5-1). It is recognized that the application packet receiving channel, channel Ch-5, is the control channel. Therefore, the terminal 5-2 sets the frequency band of the control channel Ch-5 as the use communication band.

  Here, since the communicable band is 100 MHz, the terminal 5-2 can perform communication using up to five channels. Therefore, the reception setting unit 536 of the terminal 5-2 can receive the channels Ch-3 to Ch-7 for five channels that can be received without changing the frequency of the local signal for receiving the channel Ch-5. . On the other hand, since the local frequency is the center frequency of Ch-5, there is no channel in the communication band corresponding to the communication channels Ch-4 and Ch-5 of the other terminal (terminal 5-1) indicated by the use channel information. Ch-6 is also included. Therefore, channels Ch-3 and Ch-7 obtained by removing channels Ch-4, Ch-5, and Ch-6 from the channels Ch-3 to Ch-7 for five channels that can be received are determined as monitoring channels. As described above, whether the terminal 5-2 receives the control signal on the channel Ch-5 that is the control channel, and the other base station 1 or the other system does not transmit the signal on the channels Ch-3 and Ch-7. Monitor whether. The setting of the target band at this time is shown in FIG.

  FIG. 18 is a diagram illustrating the communication band used and the monitoring band of the terminal 5-2. In the figure, the frequency of the local signal is set to 5.26 GHz which is the center frequency of the control channel (channel Ch-5). The reception setting unit 536 of the terminal 5-2 prepares and sets the BPF 531 so as to receive a signal transmitted through the control channel (Ch-5), and uses the BPF 532 using the channels Ch-3 and Ch-7. Preparation is made so that the signal can be detected (step S39 in FIG. 10). The settings of BPF 531 and BPF 532 at this time are shown in FIG.

  FIG. 19 is a diagram illustrating the BPF passband of the terminal 5-2. This figure shows a frequency with DC as a reference frequency. In the figure, since the local signal DC to 10 MHz corresponds to the channel Ch-5, the pass band of the BPF 531 is set to DC to 10 MHz. Further, since 30 MHz to 50 MHz correspond to the channels Ch-3 and Ch-7, the pass band of the BPF 532 is set to 30 MHz to 50 MHz.

  Thereafter, the terminal 5-1 connects to the Internet via the base station 1 and performs browsing. Thereby, the application packet for browsing is transmitted / received between the base station 1 and the terminal 5-1. The base station 1 converts the application packet into a wireless RF signal and transmits it to the terminal 5-1 using the channels Ch-4 and Ch-5 (FIG. 11, step S41). The terminal 5-1 receives and decodes the application packet from the signal that has passed through the BPF 531, and outputs it to the upper layer processing unit 513 (FIG. 11, step S 43). At the same time, the signal detector 538 of the terminal 5-1 observes the signal level of the signal that has passed through the BPF 532 (FIG. 12, step S51). The observed signal level at this time is −80 dBm, which is lower than the threshold (FIG. 12, step S53: NO), so it is determined that the channels Ch-3 and Ch-6 can be used.

  Similarly, the signal detection unit 538 of the terminal 5-2 observes the signal level of the signal that has passed through the BPF 532 (FIG. 12, step S51). Since the observed signal level at this time is −84 dBm, which is lower than the threshold value, it is determined that the channels Ch-3 and Ch-7 can be used (FIG. 12, step S53: NO). Thereafter, this process is repeated.

Next, a procedure in which the terminal 5-2 connects to the Internet via the base station 1 and performs browsing will be described. However, it is assumed that the terminal 5-1 only receives the monitoring channel.
First, when the user inputs an instruction for trying to connect to the Internet via the base station 1 to the terminal 5-2, the upper layer processing unit 513 recognizes this operation, and a communication start packet is transmitted to the base station 1. (FIG. 10, step S30). Based on the communication start request packet received from the terminal 5-2, the base station 1 determines to transmit an application packet on three channels (60 MHz) of channels Ch-3, Ch-4, and Ch-5 (FIG. 10, In step S31, S33), the used channel information packet is transmitted to all terminals 5 (FIG. 10, step S35). Here, the base station 1 is scheduled to use the communication channel information for setting the channels Ch-3, Ch-4, and Ch-5, the control channel information for setting the channel Ch-5, and the communication channel described above. A use channel information packet is generated from the use channel information storing the destination information in which the identification information of the terminal 5-2 is set, and transmitted to all the terminals 5 using the channel Ch-5 which is a control channel. At the same time, the frequency of the local signal is set to 5.24 GHz, which is the center frequency of the frequency band (5.21 GHz to 5.27 GHz) of the entire channel Ch-3 to Ch-5.

  The terminal 5-2 receives the usage channel information packet (FIG. 10, step S37), acquires the usage channel information, transmits application data to its own terminal, and channels Ch-3 and Ch-4. , Ch-5 is an application packet receiving channel, and channel Ch-5 is a control channel. The terminal 5-2 uses the frequency band of the channels Ch-3 to Ch-5 as the use communication band.

  Here, since the communicable band is 100 MHz, the terminal 5-2 can perform communication using up to the maximum number of channels 5. Therefore, the reception setting unit 536 of the terminal 5-2 starts from the channels Ch-2 to Ch-6 for five channels that can be received without changing the frequency of the local signal for receiving the channels Ch-3 to Ch-5. The channels Ch-2 and Ch-6 excluding the channel used by the terminal are determined as monitoring channels. As described above, the terminal 5-2 receives the application packet through the channels Ch-3, Ch-4, and Ch-5, and the other base station 1 and the other system use the channels Ch-2 and Ch-6. Decide to monitor for the absence. The setting of the target band at this time is shown in FIG.

  FIG. 20 is a diagram illustrating the communication band used and the monitoring band of the terminal 5-2. The frequency of the local signal is set to a center frequency of 5.24 GHz of channels Ch-3 to Ch-5 that are used channels. The reception setting unit 536 of the terminal 5-2 prepares and sets the BPF 531 so as to receive signals transmitted through the channels Ch-3, Ch-4, and Ch-5, and sets the BPF 532 to the channels Ch-2 and Ch. Preparation is made so that the signal can be detected using -6 (FIG. 10, step S39). FIG. 21 shows the settings of BPF 531 and BPF 532 at this time.

  FIG. 21 is a diagram illustrating a BPF passband of the terminal 5-2. This figure shows a frequency with DC as a reference frequency. In the figure, since the local signal DC to 30 MHz corresponds to the channels Ch-3, Ch-4, and Ch-5, the pass band of the BPF 531 is set to DC to 30 MHz. Also, since 30 MHz to 50 MHz correspond to the channels Ch-2 and Ch-6, the pass band of the BPF 532 is set to 30 MHz to 50 MHz.

  Similarly, the terminal 5-1 receives the usage channel information packet (FIG. 10, step S37), acquires the usage channel information, and the channels Ch-3, Ch-4, and Ch-5 are the other stations (terminal 5). -2) Recognize that the channel for receiving application packets addressed to channel Ch-5 is a control channel. Therefore, the reception setting unit 536 of the terminal 5-1 sets the frequency band of the channel Ch-5 as the use communication band. Since the terminal 5-1 has a communicable band of 80 MHz, it can receive the channels Ch-4 and Ch-6 at the center frequency of 5.26 GHz. The reception band of these channels is the other station (terminal 5-2). The monitoring bandwidth is not set because it overlaps with the other usage channels. FIG. 22 shows the setting of the target band when the terminal 5-1 only receives control signals on the channel Ch-5.

  FIG. 22 is a diagram illustrating band setting when the terminal 5-1 only receives a control signal. In the figure, the frequency of the local signal is set to the center frequency 5.26 GHz of the control channel (channel Ch-5) so that the BPF 531 can receive a signal transmitted through the control channel (channel Ch-5). Make preparations. FIG. 23 shows the setting of the BPF 531 at this time.

  FIG. 23 is a diagram showing the passband of the BPF of the terminal 5-1. This figure shows a frequency with DC as a reference frequency. In the figure, since the local signal DC to 10 MHz corresponds to the channel Ch-5, the pass band of the BPF 531 is set to DC to 10 MHz.

  Note that the signal detector 538 of the terminal 5-1 or the terminal 5-2 observes the signal level of the signal that has passed through the BPF 532 (FIG. 12, step S51), and the signal level of the channel observed at this time is the threshold value. Is detected (FIG. 12, step S53: YES), a signal detection information packet in which the detected channel number is set is transmitted to the base station 1 (FIG. 12, step S55). The base station 1 writes the unavailable information in the channel information table in association with the channel number set in the received signal detection information packet (steps S57 and S59 in FIG. 12). In addition, when a channel that is being used becomes unavailable, channel reallocation is performed. Thereafter, this process is repeated.

Through the processing described above, it is possible to sense a frequency band other than the use frequency band by making maximum use of a band in which the terminal can communicate while transmitting and receiving signals. In addition, since the base station transmits use channel information to all terminals using a control channel that can be received by all terminals, the base station and other terminals in the same service area or in the same unlicensed system Even in a situation where a signal is transmitted, it can be distinguished from a signal transmitted by another base station or a license system, and sensing can be performed without error.
In addition, since sensing is performed at the terminal, it is possible to detect interference from a base station or another system outside the communicable area of the base station.

  In the present embodiment, the availability of the channel is determined from the measurement result of the received power level. However, the present invention is not limited to this. For example, the method of analyzing the characteristics of signals transmitted by other base stations may be used. It is possible to determine the availability. In other words, if it is detected in the signal that specific information indicating that the signal is a signal transmitted from another base station is set, the channel used by the other base station, that is, unavailable. Judged to be a channel. For example, a preamble of a specific pattern transmitted by another base station, a cell number or SSID (Service Set Identifier) different from the base station with which the terminal is communicating are detected.

In the present embodiment, the use channel information is transmitted using the use channel information packet when communication is performed between the base station 1 and the terminal 5, but this is not restrictive, and between the base station 1 and the terminal 5. Communication channels and control channels used in the above may be set in advance.
Further, the communicable bandwidth of each terminal 5 may be stored in the base station 1 in advance.

In the present embodiment, the number of control channels is one. However, the present invention is not limited to this, and two or more control channels may exist.
In this embodiment, the BPF based on digital signal processing is assumed. However, similar processing can be performed using an analog BPF that can change the passband.
In the present embodiment, BPF is used in digital signal processing, but a Fourier transformer may be used.
In addition, the wireless communication standard, the number of channels, and the channel bandwidth applied to the wireless communication system are merely examples, and are not limited to those described in the embodiments.
In this embodiment, the terminal having the signal detection unit determines whether or not the channel can be used. However, the present invention is not limited to this, and the terminal notifies the base station of the channel number in which the signal is detected, and the base station determines whether or not the channel can be used. You may do it. In this case, the availability can be determined based on information notified from a plurality of terminals. For example, when 50% or more of all terminals are notified that a signal is detected on a certain channel number, the base station determines that the channel cannot be used.
In this embodiment, the analog demodulator generates a local signal having a frequency that converts the signal transmitted through the usage channel into a baseband signal. However, the present invention is not limited to this. For example, an IF (Intermediate Frequency) signal is generated. A local signal having a frequency to be converted may be generated. As an advantage, the monitoring band can be set flexibly. However, in this case, it is necessary to convert the IF signal into a baseband signal in the received digital signal processing unit.

[Second Embodiment]
Subsequently, a second embodiment of the present invention will be described. The wireless communication system of the present embodiment uses an OFDM (Orthogonal Frequency Division Multiplexing) communication scheme. In the first embodiment, the BPF is used for the terminal 5, but in this embodiment, the Fourier transformer also serves as the BPF. Hereinafter, the difference from the first embodiment will be mainly described.

  The wireless communication system of this embodiment has a configuration in which the terminal 5 of the wireless communication system in the first embodiment shown in FIG. 1 is a terminal 5a. Hereinafter, the plurality of terminals 5a are described as a terminal 5a-1, a terminal 5a-2,.

The configuration of the base station 1 of this embodiment is the same as that of the first embodiment shown in FIGS. However, the packet modulation unit 124 of the base station 1 generates an OFDM signal, and the packet demodulation unit 131 demodulates the OFDM signal.
The configuration of the terminal 5a of the present embodiment is such that the reception digital signal processing unit 510 provided in the terminal 5 of the first embodiment is replaced with the reception digital signal processing unit 510a shown in FIG. The configuration is the same as that of the terminal 5 of the first embodiment. However, the packet modulation unit 525 of the terminal 5a generates an OFDM signal.

  FIG. 24 is a block diagram illustrating a detailed configuration of the reception digital signal processing unit 510a of the terminal 5a of the present embodiment. In this figure, the same parts as those of the reception digital signal processing unit 510 of the first embodiment shown in FIG. The reception digital signal processing unit 510a shown in the figure is different from the reception digital signal processing unit 510 of the first embodiment in that BPFs 531 and 532 are not provided, a packet demodulation unit 533, a reception setting unit 536, and a signal detection unit. Instead of 538, a packet demodulation unit 533a, a reception setting unit 536a, and a signal detection unit 538a are provided.

The packet demodulator 533a demodulates the packet based on the OFDM communication method, outputs a packet demodulated and decoded for the used communication band to the packet analyzer 534, and outputs a signal received in the monitoring band to the signal detector 538a.
The reception setting unit 536a determines the usage channel and the monitoring channel based on the communication channel information and the control channel information set in the received usage channel information, and outputs the local signal information to the local signal control unit 503. Pass band information in which the used communication band and the monitoring band are set is output to the packet demodulator 533a. In this embodiment, since demodulation is performed by FFT (Fast Fourier Transform), if the use communication band is included in the reception band of the communicable bandwidth, the monitoring band is reduced. It is possible to arbitrarily set the frequency side, the high frequency side, or both the low frequency side and the high frequency side.
The signal detection unit 538a detects a signal from the demodulation result output from the packet demodulation unit 533a.

  FIG. 25 is a block diagram showing a detailed functional configuration of the packet demodulator 533a. As shown in the figure, the packet demodulation unit 533a includes a preamble detection unit 541, a timing / frequency synchronization unit 542, a GI removal unit 543, an FFT operation unit 544, an equalization unit 545, a demapping unit 546, a deinterleaver 547, and The error correction decoding unit 548 is configured to have the same configuration as the packet demodulation unit 533 of the first embodiment except for the GI removal unit 543 and the FFT calculation unit 544.

The preamble detector 541 detects the preamble of the packet. The timing / frequency synchronization unit 542 matches the timing and frequency based on the preamble detected by the preamble detection unit 541 so that the packet can be demodulated. The GI removal unit 543 removes the guard interval (GI) from the packet. When the FFT operation unit 544 performs fast Fourier transform processing on the packet from which the GI has been removed and converts the packet into a frequency domain I / Q signal, the signal in the used communication band is obtained according to the passband information received from the reception setting unit 536a. Is output to the equalization unit 545, and a signal in the monitoring band is output to the signal detection unit 538a. The equalization unit 545 equalizes the I / Q signal of the FFT calculation result output from the FFT calculation unit 544. The demapping unit 546 converts the I / Q signal equalized by the equalization unit 545 into a signal before mapping. The deinterleaver 547 performs a rearrangement process on the signals generated by the demapping unit 546. Error correction decoding section 548 corrects the error of the signal rearranged by deinterleaver 547.
The FFT operation unit 544 described above also serves as the BPFs 531 and 532 in the first embodiment.

Next, processing of the wireless communication system according to the present embodiment will be described.
The operation start processing flow, communication start processing flow, and application data transmission / reception flow of the base station 1 and terminal 5a of the present embodiment are the operation start processing of the base station 1 and terminal 5 according to the first embodiment shown in FIGS. This is the same as the flow, the communication start processing flow, and the application data transmission / reception flow. Further, the availability determination processing flow of the terminal 5a that is transmitting and receiving the application signal is the same as the availability determination processing flow shown in FIG.

FIG. 26 is a diagram showing a process flow for determining whether to use the terminal 5a that is not transmitting / receiving an application signal among the terminals 5a according to the present embodiment. In the present embodiment, the terminal 5a that is not transmitting / receiving the application signal periodically changes the frequency of the local signal using the monitoring band change timer, and determines whether or not a channel other than the use channel can be used.
Note that the terminal 5a does not transmit / receive application signals by recognizing the processing status of the upper layer by the upper layer processing unit 513 or that the use channel information packet and application packet have not been transmitted / received for a certain period. Can be judged.

  In the figure, the terminal 5a that is not transmitting / receiving the application signal sets a monitoring band change timer (not shown) provided therein (step S61), and executes the availability determination processing flow shown in FIG. 12 for monitoring. It is determined whether or not the channel can be used (step S63). The terminal 5a does not change the frequency of the local signal until the monitoring band change timer expires (step S65: NO), and repeatedly executes step S63 (usability determination processing flow shown in FIG. 12) using the same monitoring channel. When the monitoring band change timer expires (step S65: YES), the frequency of the local signal is changed, the monitoring channel is changed (step S67), and the processing from step S61 is performed. At this time, the frequency of the local signal is changed within a range where the control channel signal can be received.

  Hereinafter, an example of communication processing when the terminals 5a-1 and 5a-2 exist in the service area of the base station 1 and the terminal 5a-1 connects to the Internet via the base station 1 and performs browsing will be shown. The channels that can be used by the wireless communication system are assumed to be the same as the channels shown in FIG.

  By the process of FIG. 8, when the base station 1 is activated, it is assumed that the reception power level of all channels is measured, it is determined that all channels can be used, and the operation is started on the channel Ch-5 from among them. 9, the terminal 5a-1 and the terminal 5a-2 try to receive beacons on each channel in order from the channel Ch-1, and succeed in receiving beacons on the channel Ch-5. The assignment is completed, and the terminal 5a-1 and the terminal 5a-2 are in a state to which the base station 1 belongs.

  There are no other base stations 1 or other system radio stations in the vicinity, and the channel information table of the base station 1 is “available” for all eight channels as shown in FIG. Base station 1 has selected channel Ch-5 as the control channel.

  Depending on the performance of various analog devices, DACs, and ADCs, it is assumed that the base station 1 can communicate in a band up to 80 MHz, the terminal 5a-1 can communicate in a band up to 60 MHz, and the terminal 5a-2 can communicate in a band up to 80 MHz. Further, the channel availability determination in the base station 1 and the terminal 5a is performed by observing the signal level, and in the base station 1 and the terminal 5a, −60 dBm is set as a threshold value. In addition, the time for the terminal 5a to periodically change the frequency of the local signal (monitor band change timer) is set to 3200 microseconds.

A procedure in which the terminal 5a-1 connects to the Internet via the base station 1 and performs browsing will be described.
First, the base station 1 determines a communication channel based on the communication start request packet received from the terminal 5a-1 by the same procedure as in the first embodiment (FIG. 10, step S33), and uses channel information packet. Is transmitted to all terminals 5a (FIG. 10, step S35). Here, two channels (40 MHz) of channels Ch-4 and Ch-5 are assigned to the terminal 5a-1 to be communication channels. The base station 1 includes communication channel information for setting channels Ch-4 and Ch-5, control channel information for setting channel Ch-5, and identification information of the terminal 5a-1 that is scheduled to use the communication channel. Is generated from the use channel information storing the destination information in which the destination information is set, and transmitted to all the terminals 5a using the channel Ch-5 which is a control channel. At the same time, the frequency of the local signal is set to 5.25 GHz, which is the center frequency of the entire frequency band (5.23 GHz to 5.27 GHz) of channels Ch-4 and Ch-5, which are channels used by the terminal 5a-1.

  The terminal 5a-1 receives the usage channel information packet (FIG. 10, step S37), acquires the usage channel information, transmits application data to the terminal itself, and channels Ch-4 and Ch-5. Recognizes that the application packet reception channel and channel Ch-5 is the control channel. The terminal 5a-1 uses the frequency bands of channels Ch-4 and Ch-5 as the use communication band.

  Here, since the communicable band is 60 MHz, the terminal 5a-1 can perform communication using up to the maximum number of channels 3. For this reason, the terminal 5a-1 uses one channel adjacent to the low frequency side or the high frequency side of the frequencies of the channels Ch-4 and Ch-5 as the use channels as a monitoring channel. Here, the channel Ch-6 on the high frequency side is determined as the monitoring channel. As described above, whether or not the terminal 5a-1 receives the application packet through the channels Ch-4 and Ch-5, and the other base station 1 and the other system are not transmitting signals using the channel Ch-6. Decide to monitor. The setting of the target band at this time is shown in FIG.

  FIG. 27 is a diagram illustrating the communication band used and the monitoring band of the terminal 5a-1. In the figure, the frequency of the local signal is set to the center frequency 5.26 GHz of the channels Ch-4 to Ch-6 in the reception band including the usage channel and the monitoring channel. In addition, the reception setting unit 536a uses the FFT calculation unit 544 in the reception digital signal processing unit 510a to send signals in the frequency bands (utilization communication bands) of the utilization channels Ch-4 and Ch-5 to the equalization unit 545 and to monitor channels. It is set to output a signal in the Ch-6 frequency band (monitoring band) to the signal detection unit 538a. This setting is shown in FIG.

  FIG. 28 is a diagram illustrating setting of the used communication band and the monitoring band in the FFT calculation unit 544 of the terminal 5a-1. This figure shows a frequency with DC as a reference frequency. As shown in the figure, the FFT operation unit 544 of the terminal 5a-1 outputs signals of DC to 10 MHz, 30 MHz to 60 MHz corresponding to the use channels Ch-4 and Ch-5 to the equalization unit 545, and monitors channels. A 10 MHz to 30 MHz signal corresponding to Ch-6 is output to the signal detector 538a.

  Similarly, the terminal 5a-2 receives the usage channel information packet (FIG. 10, step S37), acquires the usage channel information, and the channels Ch-4 and Ch-5 are addressed to the other station (terminal 5a-1). It is recognized that the application packet receiving channel, channel Ch-5, is the control channel. Therefore, the terminal 5a-2 uses the frequency band of the channel Ch-5 as a use communication band.

  Here, since the communicable band is 80 MHz, the terminal 5a-2 can perform communication using up to four channels. Therefore, the terminal 5a-2 uses, as a monitoring channel, a channel other than the use channel of the other terminal 5a among the three channels adjacent to the low frequency side or the high frequency side of the frequency of the channel Ch-5 that is the use channel. To do. Here, the channels Ch-6, Ch-7, and Ch-8 on the high frequency side that do not include the communication channel of the other terminal 5a are determined as the monitoring channels. As described above, the terminal 5a-2 receives the control signal on the channel Ch-5 that is the control channel, while the other base station 1 and the other system use the channels Ch-6, Ch-7, and Ch-8. Monitor for signal transmission. The setting of the target band at this time is shown in FIG.

  FIG. 29 is a diagram illustrating the communication band used and the monitoring band of the terminal 5a-2. In the figure, the frequency of the local signal is the center frequency of the channel Ch-5 in the lowest frequency band and the channel Ch-8 in the highest frequency band among the channels including the utilization channel and the monitoring channel, that is, reception. The center frequency of the band is set to 5.29 GHz. Further, in the FFT operation unit 544 in the reception digital signal processing unit 510a, the frequency band (use communication band) signal of the use channel Ch-5 is sent to the equalization unit 545, and the monitoring channels Ch-6, Ch-7, Ch- It is set to output a signal of 8 frequency bands (monitoring band) to the signal detection unit 538a. This setting is shown in FIG.

  FIG. 30 is a diagram illustrating setting of the used communication band and the monitoring band in the FFT calculation unit 544 of the terminal 5a-2. This figure shows a frequency with DC as a reference frequency. As shown in the figure, the FFT operation unit 544 of the terminal 5a-2 outputs a signal of 40 MHz to 60 MHz corresponding to the usage channel Ch-5 to the equalization unit 545, and monitors channels Ch-6, Ch-7, Signals of DC to 40 MHz and 60 MHz to 80 MHz corresponding to Ch-8 are output to the signal detection unit 538a.

  Thereafter, the terminal 5a-1 connects to the Internet via the base station 1 and performs browsing. Thereby, an application packet for browsing is transmitted and received between the base station 1 and the terminal 5a-1. The base station 1 converts the application packet into a radio RF signal and transmits it to the terminal 5a-1 using the channel Ch-5 (FIG. 11, step S41). The application packet of the used communication band output from the FFT operation unit 544 of the packet demodulation unit 533a to the equalization unit 545 side in the terminal 5a-1 is decoded by the application packet decoding unit 537 and passed to the upper layer processing unit 513. At the same time, in the terminal 5a-1, the signal detection unit 538a observes the signal level of the monitoring band output from the FFT operation unit 544 of the packet demodulation unit 533a. The observed signal level at this time is −80 dBm, which is lower than the threshold value (FIG. 12, step S53: NO), so it is determined that the channel Ch-6 can be used.

  Similarly, the signal detection unit 538a of the terminal 5a-2 observes the signal level of the monitoring band output from the FFT calculation unit 544 of the packet demodulation unit 533a. The observed signal level at this time is −84 dBm, −86 dBm, and −94 dBm in the channel band of each of the channels Ch-6, Ch-7, and Ch-8, and is lower than the threshold value. Therefore, the channel Ch-6, Ch-7 and Ch-8 are determined to be usable.

  When three hundred microseconds have elapsed, the terminal 5a-2 that is not performing communication changes the frequency of the local signal and the monitoring band. Since the terminal 5a-2 uses the three channels adjacent to the high frequency side of the use channel Ch-5 of its own terminal as the monitoring channel, the monitoring channel is the three channels adjacent to the low frequency side of the use channel Ch-5. Of the channels Ch-2, Ch-3, and Ch-4, the channels Ch-2 and Ch-3 excluding the usage channel Ch-4 of the other terminal 5 are determined as monitoring channels. As described above, the terminal 5a-2 receives the control signal on the channel Ch-5 that is the control channel, and the other base station 1 and the other system transmit signals using the channels Ch-2 and Ch-3. Monitor whether or not. The setting of the target band at this time is shown in FIG.

  FIG. 31 is a diagram showing the communication bandwidth used and the monitoring bandwidth of the terminal 5a-2. In the figure, the frequency of the local signal is the channel Ch-2 in the lowest frequency band and the channel Ch in the highest frequency band among the channels Ch-2, Ch-3, and Ch-5 that combine the use channel and the monitoring channel. The center frequency of −5, that is, the center frequency of the reception band is set to 5.23 GHz. In addition, the reception setting unit 536a outputs the signals of the frequency bands (monitoring bands) of the monitoring channels Ch-2 and Ch-3 to the signal detection unit 538a in the FFT calculation unit 544 in the reception digital signal processing unit 510a. Set. This setting is shown in FIG.

FIG. 32 is a diagram illustrating setting of a use communication band and a monitoring band in the FFT calculation unit 544 of the terminal 5a-2. This figure shows a frequency with DC as a reference frequency. As shown in the figure, the FFT operation unit 544 of the terminal 5a-2 outputs a signal of 20 to 40 MHz corresponding to the usage channel Ch-5 to the equalization unit 545, and transmits it to the monitoring channels Ch-2 and Ch-3. A corresponding 40 MHz to 80 MHz signal is output to the signal detection unit 538a.
After this setting, the terminal 5a-2 determines whether the channels Ch-2 and Ch-3 can be used.

  Thereafter, the terminal 5a-2 changes the monitoring band to the high frequency side and the low frequency side of the use communication band every three hundred microseconds, and determines whether the channels Ch-6, Ch-7, Ch-8 can be used, The availability of channels Ch-2 and Ch-3 is periodically determined. This change is shown in FIG.

  FIG. 33 is a diagram showing temporal changes in the used communication band and the monitoring band. In the figure, the used communication band of the terminal 5a-1 does not change over time unless reassignment is performed by the base station 1, and uses the channels Ch-4 and Ch-5. On the other hand, the monitoring band of the terminal 5a-2 is periodically divided into the high frequency side (channel Ch-6, Ch-7, Ch-8) and the low frequency band side (channel Ch-2) of the communication band used by the terminal 5a-1. , Ch-3), and changes periodically.

  When the signal detector 538a of the terminal 5a-1 or the terminal 5a-2 detects that the signal level of the monitoring channel is higher than the threshold (FIG. 12, step S53: YES), the detected channel number is The set signal detection information packet is transmitted to the base station 1 (FIG. 12, step S55). The base station 1 writes the unavailable information in the channel information table in association with the channel number set in the received signal detection information packet (steps S57 and S59 in FIG. 12). In addition, when a channel that is being used becomes unavailable, channel reallocation is performed.

Through the processing described above, in addition to the effects of the first embodiment, for the terminal 5a that does not transmit or receive signals, changing the local signal does not hinder communication, so the frequency of the local signal is periodically changed. By doing so, it is possible to sense a wider frequency band than the terminal 5a transmitting and receiving signals.
Further, according to the present embodiment, the cost is reduced by using an FFT calculator instead of the two BPFs.
Further, a communication band that can be received by the terminal is defined as a reception band, and it is possible to arbitrarily determine which of the reception band the high frequency side and the low frequency band side are allocated to the monitoring band and the use communication band.

[Third embodiment]
Subsequently, a third embodiment of the present invention will be described. In the second embodiment described above, only one local signal generator is provided, and the local signal generated from the local signal generator is switched when the monitoring band is periodically switched. However, it takes time for the local signal generator to stably generate the instructed local signal. Therefore, in this embodiment, two local signal generators are provided, and by selecting one of them, the monitoring band is switched quickly, and the monitoring band is switched even in the terminal that transmits and receives application packets. Enable monitoring.
Hereinafter, the difference from the first and second embodiments will be mainly described.

  The radio communication system of the present embodiment has a configuration in which the terminal 5 of the radio communication system in the first embodiment shown in FIG. 1 is a terminal 5b. Hereinafter, the plurality of terminals 5b are described as a terminal 5b-1, a terminal 5b-2,. As in the second embodiment, the wireless communication system according to the present embodiment transmits and receives signals based on the OFDM communication scheme.

  The configuration of the base station 1 of this embodiment is the same as that of the first embodiment shown in FIGS. However, the packet modulation unit 124 of the base station 1 generates an OFDM signal, and the packet demodulation unit 131 demodulates the OFDM signal.

  FIG. 34 is a block diagram showing the configuration of the terminal 5b of this embodiment. In the figure, the same parts as those of the terminal 5 of the first embodiment shown in FIG. The terminal 5b shown in the figure is different from the terminal 5 of the first embodiment in that a local signal control unit 503b is provided instead of the local signal control unit 503, and a single local signal generator 504 is used. Local signal generators 504-1 and 504-2 are provided, reception digital signal processing unit 510a is provided instead of reception digital signal processing unit 510, and local signal switches 514-1 and 514-2 are provided. It is a point. The reception digital signal processing unit 510a is the same as that of the second embodiment shown in FIG.

  The local signal control unit 503b receives local signal information in which a frequency to be generated is set, and instructs each of the local signal generators 504-1 and 504-2 to generate a local signal having a frequency indicated by the local signal information. To output a local signal control signal. Further, the local signal control unit 503b outputs a switch control signal, and switches between the local signal generated by the local signal generator 504-1 and the local signal generated by the local signal generator 504-2. 1, 514-2. The local signal generators 504-1 and 504-2 have the same function as the local signal generator 504 of the first embodiment. The local signal switch 514-1 switches between a local signal generated by the local signal generator 504-1 and a local signal generated by the local signal generator 504-2 according to an instruction from the local signal control unit 503b and outputs the local signal to the analog modulation unit 507. To do. The local signal switch 514-2 switches between a local signal generated by the local signal generator 504-1 and a local signal generated by the local signal generator 504-2 in accordance with an instruction from the local signal control unit 503b and outputs the local signal to the analog demodulation unit 508. To do.

Next, processing of the wireless communication system according to the present embodiment will be described.
The operation start process flow of the base station 1 and the terminal 5b, the process flow before application data transmission / reception, the application data transmission / reception flow, and the availability determination process flow of this embodiment are the same as those of the second embodiment.

  In the wireless communication system of the present embodiment, a destination address and a service area specific service area ID are stored in a packet transmitted and received between the base station 1 and the terminal 5b, and by analyzing the destination address, It is determined whether the packet is destined for the own terminal, and packets not destined for the own terminal are discarded. Further, by analyzing the service area ID, it is possible to identify whether the packet is transmitted from another service area. This process is performed in the packet analysis unit 534 of the reception digital signal processing unit 510a of the terminal 5b. This can also be applied to the first and second embodiments.

  Below, terminals 5b-1 and 5b-2 exist within the service area of base station 1, and terminals 5b-1 and 5b-2 connect to the Internet via base station 1 to perform browsing and perform communication. An example of communication processing when another base station 1 and another base station 1 start operation is shown. Hereinafter, the base station 1 in which the terminals 5b-1 and 5b-2 exist in the service area is the base station 1-1, the other base station 1 that starts operation next to the base station 1-1 is the base station 1-2, Still another base station 1 that starts operation next to the base station 1-2 is defined as a base station 1-3.

  The channels that can be used by the wireless communication system to which the base station 1-1 belongs are the same as the channels shown in FIG. 13, and there are eight channels that can be used and each channel is a 20 MHz band.

  By the process of FIG. 8, when the base station 1-1 is activated, it measures the reception power level of all channels, determines that it can be used on all channels, and starts operation on the channel Ch-5 from among them. To do. Further, by the process of FIG. 9, the terminal 5b-1 and the terminal 5b-2 try to receive a beacon on each channel in order from the channel Ch-1, and succeed in receiving the beacon on the channel Ch-5. The assignment is completed, and the terminal 5b-1 and the terminal 5b-2 belong to the base station 1-1.

There are no other base stations 1-1 or wireless stations of other systems in the vicinity, and the channel information table of the base station 1-1 is “available” for all eight channels as shown in FIG. It is. The base station 1-1 sets the channel Ch-5 as a communication channel for the terminal 5b, and selects the channel Ch-5 as the control channel.
Further, it is assumed that the base station 1-1, the terminal 5b-1, and the terminal 5b-2 are capable of communication in a band up to 80 MHz.

  The channel availability determination in the base station 1-1 and the terminal 5b is performed by observing the signal level and analyzing the received packet. The determination by observing the signal level is the same as that shown in the first embodiment, and it is determined whether or not a channel other than the use channel can be used. The analysis of the received packet is a method used to determine whether or not the currently used channel is available, and recognizes from the service area ID stored in the received packet that other base stations are transmitting signals. To determine whether the channel can be used. In the base station 1-1 and the terminal 5b, −60 dBm is set as a threshold value for channel availability determination based on signal level observation. The monitoring band change timer of the terminal 5b is set to 3 hundred microseconds.

First, a procedure in which the terminal 5b-1 connects to the Internet via the base station 1-1 and performs browsing will be described.
First, the base station 1-1 determines a communication channel based on the communication start request packet received from the terminal 5b-1 by the same procedure as in the first and second embodiments (FIG. 10, step S33). Then, the used channel information packet is transmitted to all the terminals 5b (FIG. 10, step S35). Here, channel Ch-5 is assigned to terminal 5b-1, and an application packet is transmitted. The base station 1-1 sets communication channel information for setting the channel Ch-5, control channel information for setting the channel Ch-5, and identification information for the terminal 5b-1 that is scheduled to use the communication channel. The used channel information packet is generated from the used channel information in which the destination information is stored, and transmitted to all the terminals 5b using the channel Ch-5 that is the control channel. At the same time, the frequency of the local signal is set to 5.26 GHz which is the center frequency of the channel Ch-5 (5.25 GHz to 5.27 GHz) which is the usage channel of the terminal 5b-1.

  The terminals 5b-1 and 5b-2 receive the used channel information packet (FIG. 10, step S37), acquire the used channel information, and the channel Ch-5 is an application packet receiving channel for the terminal 5b-1. Recognize that channel Ch-5 is a control channel. Since terminals 5b-1 and 5b-2 have a communicable bandwidth of 80 MHz, communication using up to four channels is possible. The reception setting unit 536a of the terminals 5b-1 and 5b-2 monitors the first frequency band of the channels Ch-2, Ch-3, and Ch-4, which are three channels on the low frequency side of the usage channel Ch-5. And the frequency band of the three channels Ch-6, Ch-7, and Ch-8 on the high frequency side of Ch-5 is set as the second monitoring band.

  The reception setting unit 536a of the terminals 5b-1 and 5b-2 uses the center frequency 5.23 GHz of the channels Ch-2 to Ch-5 that combines the first monitoring band and the communication band as the first local signal frequency. In addition, the center frequency 5.29 GHz of the channels Ch-5 to Ch-8, which combines the second monitoring band and the communication band, is set as the second local signal frequency. The reception setting unit 536a outputs the local signal information in which the first local frequency and the second local frequency are set to the local signal control unit 503b, and the local signal control unit 503b outputs the first signal to the local signal generator 504-1. The local signal control signal instructs the local signal generator 504-2 to generate the local signal having the second local signal frequency, and the local signal control signal instructs the local signal generator 504-2 to generate the local signal having the second local signal frequency. . As a result, the local signal generators 504-1 and 504-2 are set so as to output local signals of 5.23 GHz and 5.29 GHz, respectively.

After the above setting, the terminal 5b-1 sets the channels Ch-2, Ch-3, and Ch-4, which are the first monitoring bands, as the monitoring bands. The setting of the target band at this time is shown in FIG.
FIG. 35 is a diagram showing the communication bandwidth used and the monitoring bandwidth of the terminal 5b-1. In the figure, the local signal control unit 503b instructs the local signal switches 514-1 and 514-2 to switch to the local signal generator 504-1 side, and switches the frequency of the local signal to 5.23 GHz. In the reception digital signal processing unit 510a, the reception setting unit 536a monitors the frequency band of the usage channel Ch-5 and the frequency band of the monitoring channels Ch-2, Ch-3, and Ch-4. Passband information indicating the band is output to the FFT operation unit 544, and a signal of the used communication band is set to be output to the equalization unit 545 and a signal of the monitoring band is set to be output to the signal detection unit 538a. This setting is shown in FIG.

  FIG. 36 is a diagram illustrating setting of a use communication band and a monitoring band in the FFT calculation unit 544 of the terminal 5b-1. This figure shows a frequency with DC as a reference frequency. As shown in the figure, the FFT operation unit 544 of the terminal 5b-1 outputs a signal of 20 to 40 MHz corresponding to the usage channel Ch-5 to the equalization unit 545, and monitors channels Ch-2, Ch-3, A signal of DC to 20 MHz and 40 MHz to 80 MHz corresponding to Ch-4 is output to the signal detection unit 538a.

  Similarly, after the above setting, the terminal 5b-2 sets the channels Ch-6, Ch-7, and Ch-8, which are the second monitoring bands, as the monitoring bands. The setting of the target band at this time is the same as in FIG. The local signal control unit 503b of the terminal 5b-2 instructs the local signal switches 514-1 and 514-2 to output a switch control signal and switch to the local signal generator 504-2 side, and Switch the frequency to 5.29 GHz. In the reception digital signal processing unit 510a, the reception setting unit 536a monitors the frequency band of the usage channel Ch-5 and the frequency band of the monitoring channels Ch-6, Ch-7, and Ch-8. Pass band information indicating the bandwidth is output to the FFT operation unit 544, and a signal of the used communication band is set to be output to the equalization unit 545, and a signal of the monitoring band is set to be output to the signal detection unit 538a. The setting of the used communication band and the monitoring band in the FFT calculation unit 544 of the terminal 5b-2 at this time is the same as that in FIG.

  Thereafter, the terminal 5b-1 connects to the Internet via the base station 1-1 and performs browsing. Thus, browsing application packets are transmitted and received between the base station 1-1 and the terminal 5b-1. The base station 1-1 converts the application packet into a wireless RF signal and transmits it to the terminal 5b-1 using the channel Ch-5 (FIG. 11, step S41). The address of the terminal 5b-1 is stored in the destination address of this application packet.

  In the packet analysis unit 534, the terminal 5b-1 analyzes the service area ID of the packet, recognizes that the packet is transmitted from the base station 1-1 to which the terminal 5b-1 belongs, After analyzing the destination address and recognizing that the packet is addressed to its own terminal, the application packet decoding unit 134 decodes the application packet and outputs the decoded data to the upper layer processing unit 513. At the same time, the terminal 5b-1 observes the signal level in the signal detection unit 538a. The signal levels of the channels Ch-2, Ch-3, and Ch-4 observed at this time are -88 dBm, -87 dBm, and -85 dBm, respectively, and are lower than the threshold value. Therefore, the channels Ch-2, Ch-3, Ch -4 is determined to be usable.

  On the other hand, the terminal 5b-2 analyzes the service area ID of the packet in the packet analysis unit 534 and recognizes that the packet is transmitted from the base station 1-1 to which the terminal 5b-2 belongs. If the destination address is analyzed and it is recognized that the packet is not addressed to the own terminal, the packet is discarded. Further, the signal level is observed in the signal detection unit 538a. The signal levels of the channels Ch-6, Ch-7, and Ch-8 observed at this time are −73 dBm, −76 dBm, and −82 dBm, respectively, and are lower than the threshold value. Therefore, the channels Ch-6, Ch-7, and Ch− 8 is determined to be usable.

When three hundred microseconds have elapsed since the terminal 5b-1 started monitoring the channel using the first monitoring band and the terminal 5b-2 using the second monitoring band, the terminals 5b-1 and 5b-2 Change the monitoring bandwidth.
The terminal 5b-1 sets the channels Ch-6, Ch-7, and Ch-8, which are the second monitoring bands, as the monitoring bands. The local signal control unit 503b of the terminal 5b-1 instructs the local signal switches 514-1 and 514-2 to switch to the local signal generator 504-2 side, and switches the frequency of the local signal to 5.29 GHz. At the same time, in the reception digital signal processing unit 510a, the reception setting unit 536a has a use communication band in the frequency band of the use channel Ch-5, and Ch-6, Ch-7, and Ch- 8 is set so that passband information indicating that the frequency band of 8 is the monitoring band is output to the FFT calculation unit 544, a signal of the used communication band is output to the equalization unit 545, and a signal of the monitoring band is output to the signal detection unit 538a To do.

  Similarly, the terminal 5b-2 sets the first monitoring band channels Ch-2, Ch-3, and Ch-4 as monitoring bands. The local signal control unit 503b of the terminal 5b-2 instructs the local signal switches 514-1 and 514-2 to switch to the local signal generator 504-1 side, and switches the frequency of the local signal to 5.23 GHz. At the same time, in the reception digital signal processing unit 510a, the reception setting unit 536a includes a use communication band in the frequency band of the use channel Ch-5, and Ch-2, Ch-3, and Ch- The pass band information indicating that the frequency band 4 is the monitoring band is output to the FFT operation unit 544, the signal of the used communication band is output to the equalization unit 545, and the signal of the monitoring band is output to the signal detection unit 538a. Set.

  After the setting, the terminal 5b-1 monitors the channels Ch-6, Ch-7, and Ch-8 while receiving the application packet through the channel Ch-5, and determines whether or not it can be used. Similarly, the terminal 5b-2 monitors the channels Ch-2, Ch-3, and Ch-4 while receiving the application packet through the channel Ch-5, and determines whether or not it can be used.

Thereafter, the terminal 5b-1 receives the application packet on the channel Ch-5 and changes the monitoring band every three hundred microseconds, while changing the channel Ch-2, Ch-3, Ch-4, Ch-6, Ch. -7 and Ch-8 are monitored to determine availability. Similarly to the terminal 5b-1, the terminal 5b-2 receives the application packet (addressed to 5b-1) on the channel Ch-5 and changes the monitoring band every three hundred microseconds, while changing the channel Ch-2. , Ch-3, Ch-4, Ch-6, Ch-7, and Ch-8 are periodically monitored to determine availability.
Note that the same operation is performed when an application packet is transmitted from the base station 1-1 to the terminal 5b-2.

Here, as shown in FIG. 37, it is assumed that the base station 1-2 implemented by the same wireless communication system as the base station 1-1 has started operation. It is assumed that the base station 1-2 has started operation on the channel Ch-7.
At this time, the monitoring bands of the terminal 5b-1 are channels Ch-2, Ch-3, Ch-4, and the monitoring bands of the terminal 5b-2 are channels Ch-6, Ch-7, Ch-8. Since the terminal 5b-2 is also present in the service area of the base station 1-2, the terminal 5b-2 receives the packet transmitted from the base station 1-2. The signal detection unit 538a of the terminal 5b-2 observes the signal level in the frequency band of the channel Ch-7 (FIG. 12, step S51), and the signal level is −36 dBm, which is higher than the threshold (FIG. 12, Step S53: YES), it is determined that the channel Ch-7 cannot be used. Upon receiving the signal detection information in which the channel number determined to be unusable is set from the signal detection unit 538a, the signal detection information packet generation unit 523 of the terminal 5b-2 stores a signal storing information indicating that the channel Ch-7 is unusable. A detection information packet is generated, and the generated signal detection information packet is transmitted to the base station 1-1 (FIG. 12, step S55).

  When the signal detection information packet is received and decoded in the base station 1-1 (FIG. 12, step S57), the signal detection information packet decoding unit 135 recognizes that the channel Ch-7 cannot be used, and the channel The information table is updated (FIG. 12, step S59). The channel information table at this time is shown in FIG.

FIG. 38 is a diagram showing the setting contents of the channel information table updated after recognizing that the channel is unavailable. In the figure, “in use” is set in the channel Ch-5, which is the control channel and the communication channel of the terminal 5b-1, and the channels Ch-2, Ch-3, Ch-4, Ch-6, “Available” is set in Ch-8, and the channel Ch-7 in which unavailable is detected is updated to “unavailable”. Further, the channel Ch-1 is updated to “unknown” because it cannot be monitored for a long time.
Since channel Ch-7 was not a communication channel before the update (FIG. 12, step S61: NO), the channel currently being used is not changed.

Subsequently, as illustrated in FIG. 39, it is assumed that the base station 1-3 realized by the same wireless communication system as the base station 1-1 has started operation on the channel Ch-5.
Since the terminal 5b-1 is also present in the service area of the base station 1-3, the terminal 5b-1 receives the packet transmitted from the base station 1-3 through the channel Ch-5. When the packet demodulator 533a of the terminal 5b-1 demodulates the received packet, and the packet analyzer 534 analyzes the service area ID of the packet and recognizes that the packet is not transmitted from the base station 1-1, the channel Ch It is determined that −5 is being used by another base station 1 and this channel is determined to be unusable. The signal detection information packet generation unit 523 of the terminal 5b-1 generates a signal detection information packet storing information indicating that the channel Ch-5 cannot be used, and the generated signal detection information packet is sent to the base station 1-1. It is transmitted (FIG. 12, step S55).

  When the signal detection information packet is received / decoded in the base station 1-1, the signal detection information packet decoding unit 135 recognizes that the channel Ch-5 is unavailable and updates the channel information table (see FIG. 12, Step S59). The channel information table at this time is shown in FIG.

  FIG. 40 is a diagram showing the setting contents of the channel information table updated after recognizing that the channel is unavailable. As shown in the figure, the channel Ch-5 is updated to “unusable” with respect to the setting contents of the channel information table shown in FIG.

  The base station 1-1 cannot use the channel Ch-5 that was being used (FIG. 12, step S61: YES), so the channel Ch-3 of the currently available channel is assigned to the terminal 5b-1. The channel is set as a communication channel, and channel Ch-3 is selected as the control channel (FIG. 10, step S33). The base station 1-1 sets communication channel information for setting the channel Ch-3, control channel information for setting the channel Ch-3, and identification information for the terminal 5b-1 scheduled to use the communication channel. A usage channel information packet is generated from the usage channel information storing the destination information, and transmitted to all terminals 5b in the service area of the base station 1-1 using the channel Ch-5 as a control channel (FIG. 10). Step S35). At the same time, the base station 1-1 sets the frequency of the local signal to the center frequency 5.22 GHz of the channel Ch-3.

  The terminals 5b-1 and 5b-2 receive the usage channel information packet (FIG. 10, step S37), acquire the usage channel information, and the channel Ch-3 is the application packet reception channel and channel of the terminal 5b-1. Recognize that Ch-3 is the control channel. Since the terminals 5b-1 and 5b-2 have only two channels on the low frequency side of the channel Ch-3, one channel on the high frequency side is added, and the frequency bands of the channels Ch-1, Ch-2, and Ch-4 are added. Is set as the first monitoring band, and the frequency bands of the three channels Ch-4, Ch-5, and Ch-6 on the higher frequency side of the channel Ch-3 are set as the second monitoring band. Further, the terminals 5b-1 and 5b-2 are configured so that the local signal generators 504-1 and 504-2 have a center frequency of 5.21 GHz for the channels Ch-1 to Ch-4 and the centers of the channels Ch-3 to Ch-6, respectively. It is set to output a local signal with a frequency of 5.25 GHz.

  After the above setting, the terminal 5b-1 sets the channels Ch-1, Ch-2, and Ch-4, which are the first monitoring bands, as the monitoring bands, and uses the local signal switches 514-1 and 514-2. In addition to switching the frequency of the local signal to 5.21 GHz, in the reception digital signal processing unit 510a, the FFT operation unit 544 outputs the signal in the used communication band to the equalization unit 545 and the signal in the monitoring band to the signal detection unit 538a. Set as follows.

  Similarly, the terminal 5b-2 sets the channels Ch-4, Ch-5, and Ch-6, which are the second monitoring bands, as monitoring bands, and uses the local signal switches 514-1 and 514-2 to transmit local signals. The frequency is switched to 5.25 GHz, and in the reception digital signal processing unit 510a, the FFT calculation unit 544 is set to output the signal in the used communication band to the equalization unit 545 and the signal in the monitoring band to the signal detection unit 538a. .

  Thereafter, the base station 1-1 transmits an application packet to the terminal 5b-1 using the channel Ch-3. Also, the terminals 5b-1 and 5b-2 periodically monitor the channels Ch-1, Ch-2, Ch-4, Ch-5, and Ch-6 while receiving application packets on the channel Ch-3. , Judge whether or not to use.

As described above, in the present embodiment, it is possible to switch the local signal input to the analog modulation unit and the analog demodulation unit using the local signal switch, and it does not take time to change the frequency of the local signal. Therefore, the communicating terminal can sense a wider frequency band than the first and second embodiments. Also, by analyzing the packets received through the usage channel, other base stations and other terminals operating at the same frequency, or base stations and other terminals within the license system operating at the same frequency Even in a situation where a signal is being transmitted, it can be distinguished from a signal transmitted by another base station 1 or the license system, and the same effect can be obtained that enables sensing without error.
According to the present embodiment, since the monitoring band can be switched quickly, it is effective, for example, when it is necessary to always search a wide frequency band in the destination in a low priority terminal or base station.
In the present embodiment, the terminal 5b-1 determines that the channel Ch-5 cannot be used when receiving a packet transmitted from the base station 1-3. However, the present invention is not limited to this. For example, the service is included in the packet. The area priority information is stored, and the terminal 5b-1 analyzes the packet at the time of reception to obtain the priority information, and determines that the terminal 5b-1 cannot be used only when it is determined that the priority is higher than the priority of the own service area. Processing is possible.

[Fourth Embodiment]
Next, a fourth embodiment of the present embodiment will be described. In the first embodiment described above, the channel is monitored on the terminal side, but in this embodiment, the channel is monitored on the base station side.

  FIG. 41 is a configuration diagram of the radio communication system according to the present embodiment. In the figure, the wireless communication system is composed of a base station 1c and a terminal 5c. In the figure, a plurality of terminals 5c capable of wireless communication with the base station 1c exist within the service area of the base station 1c, and a communication link is established between the base station 1c and each terminal 5c.

  FIG. 42 is a block diagram showing an internal configuration of the base station 1c of the present embodiment. In the figure, the same parts as those of the base station 1 of the first embodiment shown in FIG. The base station 1c shown in the figure is different from the base station 1 of the first embodiment shown in FIG. 2 in that a reception digital signal processing unit 110c is provided instead of the reception digital signal processing unit 110, and a use channel is determined. The use channel determining unit 112c is provided instead of the unit 112.

The reception digital signal processing unit 110c performs processing according to the result of demodulating and decoding the signal of the channel in the used communication band and detects the presence or absence of the signal in the monitoring band. The use channel determination unit 112c determines the communication channel and the control channel based on the state of each frequency channel indicated by the channel information table and the communication start request information received from the terminal 5c, and transmits the use channel information to the digital signal processing. To the unit 105, the local signal information is output to the local signal control unit 103, and the passband information is output to the reception digital signal processing unit 110c.
The transmission digital signal processing unit 105 is the same as that of the first embodiment shown in FIG. 3, but the usage channel information packet generation unit 121 receives usage channel information from the usage channel determination unit 112c.

  FIG. 43 is a block diagram illustrating a detailed functional configuration of the reception digital signal processing unit 110c of the base station 1c. In this figure, the same parts as those of the received digital signal processing unit 110 of the base station 1 of the first embodiment shown in FIG. 4 is different from the reception digital signal processing unit 110 of the first embodiment shown in FIG. 4 in that BPFs 136 and 137 and a signal detection unit 138 are provided, and a communication start request packet. Instead of the decoding unit 133, a communication start request packet decoding unit 133c is provided.

  The BPFs 136 and 137 are digital BPFs having a variable pass band, set the pass band based on the pass band information received from the use channel determining unit 112c, and pass signals in the set pass band. The BPF 136 passes the frequency band (use communication band) of the use channel of the communication destination terminal 5c and outputs it to the packet demodulator 131, and the BPF 137 passes the frequency band (monitor band) of the monitoring channel. The signal detection unit 138 determines whether a signal exists after passing through the BPF 137, and reflects the determination result in the channel information table. Moreover, the signal detection part 138 transmits a starting trigger to the utilization channel determination part 112c, when a signal is detected. The communication start request packet decoding unit 133c acquires communication start request information from the communication start request packet transmitted from the terminal 5c, and transmits the start trigger and the communication start request information to the use channel determination unit 112c.

FIG. 44 is a block diagram showing an internal configuration of the terminal 5c according to the present embodiment. In the figure, the same parts as those of the terminal 5 of the first embodiment shown in FIG. The terminal 5c shown in the figure is different from the terminal 5 of the first embodiment shown in FIG. 5 in that a transmission digital signal processing unit 505c is provided instead of the transmission digital signal processing unit 505, and in the reception digital signal processing unit 510. Instead, a reception digital signal processing unit 510c is provided.
The transmission digital signal processing unit 505c generates a transmission digital signal for communication start request information upon activation from the upper layer processing unit 513, or generates a transmission digital signal from application data output from the upper layer processing unit 113. Or The reception digital signal processing unit 510c performs reception control according to the usage channel information when the usage channel information is obtained as a result of demodulation and decoding, and outputs to the upper layer processing unit 513 when the application data is obtained.

FIG. 45 is a block diagram illustrating a detailed functional configuration of the transmission digital signal processing unit 505c of the terminal 5c. In the figure, the same parts as those in the transmission digital signal processing unit 505 of the first embodiment shown in FIG. The transmission digital signal processing unit 505c shown in the figure is different from the transmission digital signal processing unit 505 of the first embodiment shown in FIG. 6 in that the signal detection information packet generation unit 523 is not provided and the switch 524 is changed. The switch 524c is provided.
The switch 524c switches transmission of the communication start request packet output from the communication start request packet generation unit 521 and the application packet output from the application packet generation unit 522.

FIG. 46 is a block diagram illustrating a detailed functional configuration of the reception digital signal processing unit 510c of the terminal 5c. In this figure, the same parts as those of the reception digital signal processing unit 510 of the first embodiment shown in FIG. The reception digital signal processing unit 510c shown in the figure is different from the reception digital signal processing unit 510 of the first embodiment shown in FIG. 7 in that the BPF 532 and the signal detection unit 538 are not provided, and the reception setting unit 536. Instead, a reception setting unit 536c is provided.
The reception setting unit 536c determines the use channel based on the communication channel information and control channel information set in the use channel information, derives the frequency and passband of the local signal, and indicates the local signal indicating the frequency of the local signal Information is output to the local signal control unit 103, and passband information indicating the passband of the used channel is output to the BPF 531.

Next, the processing flow of this embodiment is shown below. The terminal 5c is connected to the Internet via the base station 1c and performs communication.
The operation start process flow of the base station 1c and the operation start process flow of the terminal 5c according to this embodiment are the operation start process flow of the base station 1 shown in FIG. 8, the operation start process flow of the terminal 5 shown in FIG. It is the same.
However, when the use channel determination unit 112c determines one channel to start operation in step S17 in FIG. 8, the passband information in which the frequency band of the channel to start operation is set is received by the received digital signal processing unit 110c. Output to BPF 136. The BPF 136 sets a pass band according to the received pass band information.

FIG. 47 shows a communication start processing flow of the wireless communication system according to the present embodiment.
The terminal 5c activates the communication start request packet generation unit 521 based on the activation trigger from the higher layer processing unit 513 before starting application communication. The communication start request packet generation unit 521 outputs a switching request to the switch 524c. When the switch 524c is connected to the communication start request packet generation unit 521 side, the communication start request packet generation unit 521 generates and outputs a communication start request packet. The communication start request packet is a packetized communication start request information similar to that of the first embodiment. The communication start request packet is modulated by the packet modulator 525 and then output to the DAC 506. The terminal 5c transmits a communication start request packet to the base station 1c through the control channel (step S61).

  The communication start request packet received by the base station 1c passes through the BPF 136 of the received digital signal processing unit 110c, is demodulated by the packet demodulation unit 131, and is determined by the packet analysis unit 132 to be a communication start request packet. When the communication start request packet decoding unit 133c decodes the communication start request packet output from the packet analysis unit 132, the communication start request packet decoding unit 133c activates the use channel determination unit 112c and outputs communication start request information obtained by the decoding (step S63). .

  Based on the communication start request information, the use channel determination unit 112c determines a frequency bandwidth used for transmission / reception of application data packets. The used channel determination unit 112c refers to the channel information table, and is used for communication for transmitting and receiving packets to and from the terminal 5c on channels with consecutive channel numbers that can be used by the number of channels of the determined frequency bandwidth. Determine as a channel. The use channel determination unit 112c stores in the channel information table that the channel determined as the communication channel is being used. Further, the communication start request information received from the terminal 5c is stored in a storage unit provided therein.

  The use channel determination unit 112c sets the pass band by outputting the pass band information to the BPFs 136 and 137 so that the packet can be transmitted and received using the use channel in which the communication channel and the control channel are combined. The local signal information is output to the unit 103 and the frequency of the local signal is set (step S67). The use channel determining unit 112c sets the pass band information set as the pass band to the BPF 136 connected to the packet demodulating unit 131 and the BPF 137 connected to the signal detecting unit 138 to other than the use channel. Pass band information set with the frequency band of the channel as the pass band is output. Moreover, the center frequency of the frequency band of a utilization channel is set to local signal information. Furthermore, the use channel determination unit 112c stores in the channel information table that the channel determined as the communication channel is being used.

  The use channel determination unit 112 c outputs the use channel information in which the communication channel information and the control channel information are set to the transmission digital signal processing unit 105. When the use channel information packet generation unit 121 of the transmission digital signal processing unit 105 connects the switch 123 to the use channel information packet generation unit 121, the use channel information packet generation unit 121 stores the received use channel information and assigns a communication channel to the terminal 5c. Is generated and output as a destination channel information packet. The usage channel information packet is modulated by the packet modulation unit 124 and then output to the DAC 106. The base station 1c transmits the usage channel information packet to all the terminals 5c using the control channel (step S69).

  Each terminal 5c receives the usage channel information packet transmitted from the base station 1c (step S71). In each terminal 5c, the use channel information packet converted into the digital signal passes through the BPF 531 of the reception digital signal processing unit 510c and is output to the packet demodulation unit 533. When the packet demodulator 533 decodes the input usage channel information packet, and the packet analysis unit 534 analyzes the demodulated packet and determines that it is a usage channel information packet from the packet type, the usage channel information packet decoding unit Output to 535. The used channel information packet decoding unit 535 outputs the used channel information obtained by decoding the used channel information packet to the reception setting unit 536c.

  The reception setting unit 536c determines the use communication band of the own terminal based on the use channel information obtained by decoding. When the reception setting unit 536c determines the communication band used by the terminal itself, the reception setting unit 536c subsequently changes the frequency of the local signal. The reception setting unit 536c outputs the local signal information in which the center frequency of the use channel of the own terminal is set to the local signal control unit 503. Further, the reception setting unit 536c outputs the pass band information in which the frequency band of the use channel is set as the pass band to the BPF 531 (step S73).

Thereafter, the base station 1c transmits the application data packet to the terminal 5c, and the terminal 5c also transmits the application data packet to the base station 1c.
The application data transmission / reception flow according to the present embodiment is the same as the application data transmission / reception flow according to the first embodiment shown in FIG.

  At the same time as the application data transmission / reception processing shown in FIG. 11, the base station 1c determines whether or not a channel other than the use channel, that is, a sensing target channel can be used.

FIG. 48 shows a processing flow for determining whether or not the base station 1c can use the signal level by observing it.
The BPF 137 of the base station 1c passes the signal of the frequency band to be sensed, and the signal detection unit 138 measures the signal level of the signal that has passed through the BPF 137 (step S81) and compares it with a predetermined threshold (step S83). . If the signal level is less than the threshold value (step S83: NO), the process is terminated. On the other hand, when the signal level exceeds the threshold (step S85: YES), the signal detection unit 138 indicates that there is a signal transmitted from another base station 1c, the terminal 5c belonging to the base station, or another system. And determine that the channel of the frequency band is unusable. The signal detection unit 138 reads the current state of the channel number determined to be unusable from the channel information table, and then writes and updates that the channel is unusable (step S85).

  Further, the signal detection unit 138 terminates the processing if the channel state before writing “unusable” is other than in use (step S87: NO), and if in use (step S87: YES), FIG. The process from step S65 of 47 is performed, and a use channel is newly allocated to the terminal 5c that has used this channel (step S89).

An example of communication processing when one terminal 5c exists in the service area of the base station 1c and the terminal 5c connects to the Internet via the base station 1c and performs browsing will be described below.
The channels that can be used by the wireless communication system are the same as the channels shown in FIG. 13, and there are eight channels that can be used, each having a bandwidth of 20 MHz.

When the base station 1c is activated by the process of FIG. 8, it measures the received power level of all channels, determines that it can be used in all channels, starts operation using the channel Ch-5 as a control channel, Send a beacon.
Further, the terminal 5c tries to receive a beacon on each channel in order from the channel Ch-1 by changing the pass band of the BPF 531 and the local signal by the process of FIG. The terminal 5c succeeds in receiving the beacon on the channel Ch-5, completes the authentication and attribution, and as shown in FIG. 49, the terminal 5c belongs to the base station 1c.

  There are no other base stations 1c or other system radio stations in the vicinity, and the channel information table of the base station 1c is “available” for all eight channels as shown in FIG. Note that the base station 1c selects the channel Ch-5 as the control channel.

  Further, it is assumed that the base station 1c can communicate in a band up to 80 MHz and the terminal 5c can communicate in a band up to 40 MHz depending on the performance of various analog devices, DACs, ADCs, and the like. In addition, the channel availability determination in the base station 1c is performed by observing the signal level, and −60 dBm is set as the threshold value.

Hereinafter, a procedure in which the terminal 5c connects to the Internet via the base station 1c and performs browsing will be described.
First, the user of the terminal 5c inputs an instruction for trying to connect to the Internet via the base station 1c. The terminal 5c recognizes this operation in the upper layer processing unit 513, and transmits a communication start request packet to the base station 1c (FIG. 47, step S61). In this embodiment, it is assumed that only information of 40 MHz is stored in the communication start request packet as a band in which the terminal 5c can communicate.

  When the base station 1c receives the communication start request packet from the terminal 5c and acquires the communication start request information, the base station 1c activates the use channel determination unit 112c (FIG. 47, step S63). The use channel determination unit 112c determines a communication channel of the terminal 5c based on the communicable bandwidth information in the communication start request information and the channel information table (FIG. 47, step S65). Assume that the base station 1c allocates two channels (40 MHz) of channels Ch-4 and Ch-5 to the terminal 5c as communication channels and transmits application packets.

  Here, since the communicable band is 80 MHz, the base station 1c can perform communication using up to four channels. Therefore, the base station 1c receives the local signals for receiving the channels Ch-4 and Ch-5, which are the channels used by the terminal 5c, in other words, the channels Ch-4 and Ch-5. The channels Ch-3 to Ch-6 in the reception band for four channels can be received without changing the frequency of. Therefore, the use channel determination unit 112c of the base station 1c sets channels Ch-3 and Ch-6 obtained by removing the use channels of the terminal 5c from the receivable channels Ch-3 to Ch-6 as monitoring channels. As described above, the base station 1c uses the channels Ch-3 and Ch-6 while using the channels Ch-4 and Ch-5 for communication with the terminal 5c, and the other base station 1c, the terminal 5c, and the other system. Decides to monitor whether it is transmitting signals. FIG. 50 shows the setting of the target band at this time.

  FIG. 50 is a diagram showing the used communication band and the monitoring band of the base station 1c. In the figure, the frequency of the local signal is set to the center frequency 5.25 GHz of the channels Ch-4 and Ch-5, which are used channels. The use channel determination unit 112c of the base station 1c prepares and sets the BPF 136 so as to receive signals transmitted on the channels Ch-4 and Ch-5, and uses the BPF 137 on the channels Ch-3 and Ch-6. Preparation is performed so that the detected signal can be detected (FIG. 47, step S67). The settings of BPF 531 and BPF 532 at this time are shown in FIG.

  FIG. 51 is a diagram showing the passband of the BPF of the base station 1c. This figure shows a frequency with DC as a reference frequency. In the figure, since the local signal DC to 20 MHz corresponds to the channels Ch-4 and Ch-5, the pass band of the BPF 136 is set to DC to 20 MHz. Further, since 20 MHz to 40 MHz correspond to the channels Ch-3 and Ch-6, the pass band of the BPF 137 is set to 20 MHz to 40 MHz.

  When the setting of the BPF passband and the frequency of the local signal is completed, the base station 1c, the communication channel information for setting the channels Ch-4 and Ch-5, the control channel information for setting the channel Ch-5, and the above A use channel information packet is generated from the use channel information storing the destination information in which the identification information of the terminal 5c scheduled to use the communication channel is set, and is transmitted to all the terminals 5c using the channel Ch-5 as the control channel. Transmit (FIG. 47, step S69).

  The terminal 5c receives the usage channel information packet (FIG. 47, step S71), acquires the usage channel information, and the channels Ch-4 and Ch-5 are communication channels and channels for receiving application packets addressed to the terminal 5c. Recognize that Ch-5 is the control channel. Since the terminals Ch-4 and Ch-5 are used channels, the terminal 5c sets the frequency of the local signal to 5.25 GHz which is the center frequency of the frequency band including the channels Ch-4 and Ch-5. Furthermore, the terminal 5c prepares and sets the pass band of the BPF 531 so that signals transmitted through the channels Ch-4 and Ch-5 can be received (FIG. 47, step S73).

Thereafter, the terminal 5c connects to the Internet via the base station 1c and performs browsing. Accordingly, browsing application packets are transmitted and received between the base station 1c and the terminal 5c using the channels Ch-4 and Ch-5. At the same time, the signal detector 138 of the base station 1c observes the signal level of the signal that has passed through the BPF 137 (FIG. 48, step S81). The signal level observed at this time is −85 dBm, which is lower than the threshold value (FIG. 48, step S83: NO), so that the channels Ch-3 and Ch-6 are determined to be usable.
Thereafter, similarly, channel Ch-3 and Ch-6 are monitored while transmitting and receiving application packets between the base station 1c and the terminal 5c.

  The signal detector 138 of the base station 1c observes the signal level of the signal that has passed through the BPF 137 (FIG. 48, step S81), and the signal level of the channel Ch-3 or Ch-6 observed at this time is less than the threshold value. Is detected (FIG. 48, step S83: YES), the fact that the detected channel is unavailable is written in the channel information table (FIG. 48, step S85).

  Through the processing described above, according to the present embodiment, it is possible to sense a frequency band other than the use frequency band by making maximum use of the range in which the base station can communicate while transmitting and receiving signals.

Note that the wireless communication system of the fourth embodiment may use an OFDM (Orthogonal Frequency Division Multiplexing) communication scheme.
In this case, the received digital signal processing unit 110c of the base station 1c of the fourth embodiment is replaced with the BPFs 136 and 137 and the packet demodulation unit 533a of the terminal 5a instead of the packet demodulation unit 131, instead of the signal detection unit 138. A signal detection unit 538a of the terminal 5a is provided. However, the packet demodulation unit 533a provided in the base station 1c receives the passband information from the use channel determination unit 112c. Then, similarly to the reception digital signal processing unit 510a of the second embodiment, the use channel determination unit 112c determines the reception band (monitoring band) and the frequency of the local signal corresponding to the reception band, and performs switching. Do.
In addition, when using the OFDM communication scheme, the packet demodulator 533a of the terminal 5a is provided in place of the BPFs 136 and 137 of the received digital signal processor 110c of the base station 1c and the packet demodulator 131 of the fourth embodiment, A signal detector 538a of the terminal 5a is provided in place of the signal detector 138, and the local signal controller of the terminal 5b is replaced with the local signal controller 103, the local signal generator 104, and the received digital signal processor 110. 503b, local signal generators 504-1 and 504-2, and local signal switches 514-1 and 514-2 may be provided. Then, similarly to the reception setting unit 536a of the terminal 1b of the third embodiment, the use channel determination unit 112c determines the reception band (monitoring band) and the frequency of the local signal corresponding to the reception band, and switches To do.

1, 1-1, 1-2, 1-3, 1c... Base station (base station apparatus)
5, 5a, 5b, 5b-1, 5b-2, 5c... Terminal (terminal device)
101, 501 ... antennas 102, 502 ... circulators 103, 503, 503b ... local signal control units 104, 504, 504-1, 504-2 ... local signal generators 105, 505, 505c ... transmission digital signal processing units 106, 506 ... Digital-to-analog signal converter (DAC)
107, 507... Analog modulation section 108, 508 ... Analog demodulation section 109, 509 ... Analog-digital signal converter (ADC)
110, 110c, 510, 510a, 510c ... received digital signal processing unit 111 ... channel information table storage unit 112, 112c ... used channel determination unit (instruction unit)
113, 513 ... upper layer processing unit 121 ... used channel information packet generation unit 122, 522 ... application packet generation unit 123, 524, 524c ... switch 124, 525 ... packet modulation unit 131, 533, 533a ... packet demodulation unit 132, 534 ... packet analysis unit 133, 133c ... communication start request packet decoding unit 134, 537 ... application packet decoding unit 135 ... signal detection information packet decoding unit 136, 137, 531, 532 ... band pass filter (BPF) (separation unit)
138, 538, 538a ... signal detectors 514-1, 514-2 ... local signal switch 521 ... communication start request packet generator 523 ... signal detection information packet generator 535 ... used channel information packet decoders 536, 536a, 536c ... Reception setting part (instruction part)
541 ... Preamble detection unit 542 ... Timing / frequency synchronization unit 543 ... Guard interval (GI) removal unit 544 ... FFT operation unit (separation unit)
545 ... Equalization unit 546 ... Demapping unit 547 ... Deinterleaver 548 ... Error correction decoding unit

Claims (9)

A wireless communication system comprising a base station device and a terminal device,
The terminal device
A local signal generator for generating a local signal;
An analog demodulator for down-converting a radio signal received from the base station apparatus using a local signal generated by the local signal generator;
And use the communication band is a frequency band of Tei Ru channel used for wireless communication with the base station apparatus and the own terminal device, the channel received is Ru include monitoring bandwidth in the frequency band of a different channel than the available communication band An instruction unit that instructs the local signal generator to generate a local signal having a frequency for receiving a radio signal according to a band;
A separation unit for separating a signal of the signal and the previous SL monitored bandwidth of the available communication band from the signal of the reception band that is down-converted by the analog demodulator,
A signal detection unit for detecting presence or absence of use of the channel of the monitoring band from the signal of the monitoring band separated by the separation unit;
With
The base station device
Based on the detection result of presence / absence of use of the channel in the monitoring band by the signal detection unit, one available from a plurality of channels in the frequency band allocated to the wireless communication system or two or more continuous frequency bands the channel determined as a channel to be used for wireless communication with the terminal device, to transmit and receive radio signals to and from the terminal device using the determined said channel,
A wireless communication system. A wireless communication system comprising a base station device and a terminal device,
The base station device
A local signal generator for generating a local signal;
An analog demodulator for down-converting a radio signal received from the terminal device using a local signal generated by the local signal generator;
Based on the detection result of the presence / absence of channel use, one or more of the channels that are available in the frequency band assigned to the radio communication system or two or more channels that are continuous in the frequency band are defined as the own base station device. the determined as a channel to be used for wireless communication with the terminal device is different from the use communication band is a frequency band of the channel used for wireless communication with the terminal apparatus and the base station apparatus, and the channel of the available communication bandwidth a local signal of a frequency for receiving the radio signal by the reception band and the monitored band Ru contains in the frequency band of the channel, an instruction unit that instructs to generate the local signal generator,
A separation unit for separating a signal of the signal and the previous SL monitored bandwidth of the available communication band from the signal of the reception band that is down-converted by the analog demodulation unit,
A signal detection unit for detecting presence or absence of use of the channel of the monitoring band from the signal of the monitoring band separated by the separation unit;
With
The terminal device
To transmit and receive radio signals to and from the base station apparatus using the channel used for wireless communication with the base station apparatus,
The instruction unit performs processing based on a detection result of presence / absence of use of the channel of the monitoring band by the signal detection unit,
A wireless communication system. The base station device and the terminal device communicate with each other by a multicarrier radio signal,
The separation unit performs Fourier transform of the downconverted signal by the analog demodulator, the signal of the Fourier transformed result signal of said available communication band from the signal of the reception band obtained in the previous SL monitored band and To separate the
The wireless communication system according to claim 1, wherein the wireless communication system is a wireless communication system. The instruction unit changes the reception band according to time so that the use communication band is always included when data is not transmitted / received to the own device,
The wireless communication system according to any one of claims claims 1 to 3, characterized in that. A plurality of the local signal generators;
The instruction unit determines a plurality of the reception bands including the use communication band, and generates a local signal having a frequency for receiving each of the determined plurality of reception bands by the plurality of local signal generators. And instructing the local signal used by the analog demodulator for down-conversion to one of the local signals generated by the plurality of local signal generators according to time.
The wireless communication system according to any one of claims of claims 1 to 4, characterized in that. The separation unit includes a first band pass filter that passes the use communication band and a second band pass filter that passes the monitoring band .
The wireless communication system according to claim 1, wherein the wireless communication system is a wireless communication system. The base station apparatus, channel determination for transmitting the use channel information indicating the channel information which was determined to use in wireless communication with the terminal device, to all of the terminals have established the base station apparatus by radio link Further comprising
The wireless communication system according to any one of claims 1 to 6 , wherein the wireless communication system is characterized by that. A sensing method used in a wireless communication system comprising a base station device and a terminal device,
The terminal device includes a local signal generator that generates a local signal ,
The terminal device is
An analog demodulation process of down-converting a radio signal received from the base station apparatus using a local signal generated by the local signal generator;
Use a communication band is a frequency band of the channel used for wireless communication with the base station apparatus and the own terminal device, the channel received is Ru include monitoring bandwidth in the frequency band of a different channel than the available communication band An instruction process for instructing the local signal generator to generate a local signal having a frequency for receiving a radio signal according to a band; and
A separation step of separating the signals of the signal and the previous SL monitored bandwidth of the available communication band from the signal of the reception band that is down-converted in the analog demodulation process,
A signal detection step of detecting whether or not the channel of the monitoring band is used from the signal of the monitoring band separated in the separation step;
One or frequency that the base station apparatus can use from a plurality of channels in the frequency band assigned to the radio communication system based on the detection result of the presence or absence of the use of the channel in the monitoring band in the signal detection process Determining two or more channels having continuous bandwidths as channels used for wireless communication with the terminal device, and transmitting and receiving wireless signals to and from the terminal device using the determined channel;
A sensing method characterized by comprising: A sensing method used in a wireless communication system comprising a base station device and a terminal device,
The base station device includes a local signal generator that generates a local signal,
The terminal device is
A process of transmitting and receiving a radio signal to and from the base station apparatus using a channel used for radio communication with the base station apparatus;
The base station device is
An analog demodulation process of down-converting a radio signal received from the terminal device by a local signal generated by the local signal generator;
Based on the detection result of the presence / absence of channel use, one or more of the channels that are available in the frequency band assigned to the radio communication system or two or more channels that are continuous in the frequency band are defined as the own base station device. It is determined as a channel used for wireless communication with the terminal device, and the used communication band that is the frequency band of the channel used for wireless communication between the own base station device and the terminal device is different from the channel of the used communication band. an instruction step of instructing a local signal of a frequency for receiving the radio signal by the reception band that is part of the monitoring zone, so as to generate the local signal generator in the frequency band of the channel,
A separation step of separating the signals of the signal and the previous SL monitored bandwidth of the available communication band from the signal of the reception band that is down-converted in the analog demodulation process,
A signal detection step of detecting whether or not the channel of the monitoring band is used from the signal of the monitoring band separated in the separation step;
I have a,
The instruction process performs processing based on a detection result of the presence or absence of use of the channel of the monitoring band in the signal detection process.
Sensing method characterized by this.

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