WO2007129737A1 - 干渉抑圧方法及び干渉抑圧装置 - Google Patents
干渉抑圧方法及び干渉抑圧装置 Download PDFInfo
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- WO2007129737A1 WO2007129737A1 PCT/JP2007/059607 JP2007059607W WO2007129737A1 WO 2007129737 A1 WO2007129737 A1 WO 2007129737A1 JP 2007059607 W JP2007059607 W JP 2007059607W WO 2007129737 A1 WO2007129737 A1 WO 2007129737A1
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
- H04B1/12—Neutralising, balancing, or compensation arrangements
- H04B1/123—Neutralising, balancing, or compensation arrangements using adaptive balancing or compensation means
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7097—Interference-related aspects
- H04B1/7103—Interference-related aspects the interference being multiple access interference
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J11/00—Orthogonal multiplex systems, e.g. using WALSH codes
- H04J11/0023—Interference mitigation or co-ordination
- H04J11/0026—Interference mitigation or co-ordination of multi-user interference
- H04J11/0036—Interference mitigation or co-ordination of multi-user interference at the receiver
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03178—Arrangements involving sequence estimation techniques
- H04L25/03248—Arrangements for operating in conjunction with other apparatus
- H04L25/0328—Arrangements for operating in conjunction with other apparatus with interference cancellation circuitry
Definitions
- the present invention relates to a technique for suppressing an interference signal superimposed on a desired signal based on a feature amount of the interference signal.
- the received signal received by the receiving radio station includes a signal addressed to itself (hereinafter referred to as a desired signal) based on the transmission of the communicating radio station (transmitting station). Included are signals (hereinafter referred to as interference signals) transmitted by radio stations (interference stations) that have nothing to do with the communication performed by the local station.
- the reception station receives the reception signal in which the interference signal is superimposed on the desired signal in the overlap period.
- the channel frequency of the desired signal and the channel frequency of the interference signal Are the same, there is a high possibility that a demodulation error of the desired signal will occur due to the influence of the interference signal.
- an interference suppression technique for suppressing an interference signal from a received signal based on a characteristic amount of the interference signal that suppresses the occurrence of a demodulation error of the desired signal when the interference signal is superimposed on the desired signal. It has become so.
- the received power of the received signal changes at a constant period, it is determined that the received signal is an interference signal, and the feature quantity of the interference signal is estimated.
- the received signal including the desired signal is received, a rare signal is obtained from the received signal using the estimated feature value of the interference signal. The interference signal superimposed on the desired signal is suppressed.
- Patent Document 1 Japanese Patent Laid-Open No. 2002-374179
- the access method is a TDMA (Time Division Multiple Access) method
- an interference signal having a fixed packet length periodically arrives at the receiving station, so that the above-described interference suppression technique can be applied.
- the access method is CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance)
- the transmitting station randomly transmits a wireless packet signal of variable packet length
- the receiving station randomly receives a wireless packet signal. It will be. Therefore, it is difficult to apply the above-mentioned interference suppression technology for periodically arriving interference signals to a wireless communication system employing the CSMA / CA method.
- the number of interference signals that can be suppressed from the received signal by the receiving station is limited due to the configuration of the receiving station such as the number of antennas provided in the receiving station. For this reason, if the receiving station previously estimated the feature quantities of the interference signals of multiple interfering stations, the feature quantity of the interference signal used by the receiving station to suppress the interference signals from the received signals is This is related to some of the multiple interfering stations whose signal features are estimated.
- the interference signal related to the interference station arbitrarily selected from the feature quantities of the interference signal related to all the previously estimated interference stations.
- feature quantities it is fully possible that a feature quantity of an interference signal other than the feature quantity of the interference signal superimposed on the desired signal being received is used. In such a case, the receiving station cannot suppress the interference signal from the received signal.
- the present invention provides an interference signal in which the feature amount of the interference signal used to suppress the interference signal from the received signal is actually superimposed on the desired signal, even in an environment where the interference signal randomly arrives. It is an object of the present invention to provide an interference suppression method and an interference suppression apparatus that can effectively suppress an interference signal from a received signal by increasing the probability of the feature amount of the received signal. Means for solving the problem
- the interference suppression method of the present invention is performed at a receiving station.
- the interference suppression method that suppresses the interference signal superimposed on the desired signal, there is a possibility that the transmission source that transmitted the signal arriving at its own station will transmit the interference signal superimposed on the desired signal based on the transmission of the transmitting station of the communication partner.
- An identification step for identifying a transmission source targeted for suppression and a transmission source not targeted for suppression a feature amount acquisition step for acquiring a characteristic amount of the signal based on a signal arriving at the own station, When a received signal including a desired signal arrives at a station, the signal is obtained based on the feature amount of the signal acquired in the feature amount acquisition step regarding the transmission source identified as the transmission source to be suppressed in the identification step, and An interference suppression step for suppressing an interference signal superimposed on the desired signal from the received signal.
- An interference suppression apparatus of the present invention is an interference suppression apparatus that suppresses an interference signal superimposed on a desired signal.
- a transmission source that transmits a signal arriving at a reception station including the own apparatus is used as a transmission station of a communication partner.
- Identification means for distinguishing between a suppression target transmission source that may transmit an interference signal superimposed on a desired signal based on the transmission of the signal and a non-suppression target transmission source that has no possibility, and a signal arriving at the local station
- a feature amount acquisition unit that acquires a feature amount of the signal based on the acquisition of the feature amount related to the transmission source identified as the transmission source to be suppressed by the identification unit when a received signal including a desired signal arrives at the local station.
- Interference suppression means for suppressing an interference signal superimposed on the desired signal from the received signal based on the feature amount of the signal acquired by the means.
- the receiving station identifies the transmission source that has transmitted the signal arriving at itself as the transmission source that is the suppression target and the transmission source that is not the suppression target.
- Received signal power As a signal feature used for suppressing an interference signal, a signal feature used for the transmission source identified as the transmission source to be suppressed is used. For this reason, the feature amount of the signal related to the transmission source that is not subject to suppression is not used as the feature amount of the interference signal used to suppress the received signal force interference signal. Therefore, the probability that the feature value of the interference signal actually superimposed on the desired signal will be used as the feature value of the signal used to suppress the interference signal from the received signal is increased, and the interference from the received signal is effectively reduced. It becomes possible to suppress the signal.
- the signal included in the signal arriving at the local station is transmitted.
- a comparison step of comparing a network identifier indicating a network to which the transmission source belongs and a network identifier indicating a network to which the local station belongs, and the identification step includes a step of comparing if both match as a result of the comparison in the comparison step.
- the transmission source that has transmitted the incoming signal may be identified as a transmission source that is not subject to suppression, and if the two do not match, the transmission source that transmitted the incoming signal may be identified as the transmission source that is subject to suppression.
- a network identifier indicating the network is a BS SID (Basic Service Set Identification).
- the transmission period of the transmitting station and the wireless station belonging to the same BSS (Basic Service Set) as the transmitting station can usually overlap. Therefore, according to these interference suppression methods, it is possible to appropriately identify the transmission source of the signal arriving at the receiving station.
- BSS Basic Service Set
- the identification step further includes a determination step of determining whether the arrival timing of the signal arriving at the own station is within a transmission prohibition period in a network to which the own station belongs. If it is determined in the determination step that the arrival timing is within the transmission prohibition period, the transmission source that transmitted the arrived signal may be identified as a transmission source to be suppressed.
- the transmission prohibition period may be a period based on IFS (Inter Frame Space).
- a wireless station belonging to the network does not normally transmit during a transmission prohibition period based on IFS or the like in the network to which the transmitting station belongs.
- a radio station belonging to a different network transmits during the transmission prohibition period or that an electronic device such as a microwave oven radiates radio waves. Therefore, according to these interference suppression methods, it is possible to appropriately identify the transmission source of the signal arriving at the receiving station.
- the receiving station transmits a QoS CF-Poll frame to the transmitting station, thereby giving the transmitting station a transmission right for a predetermined period.
- the receiving station sets the interference measurement prohibition period based on the predetermined period, the receiving station uses the desired signal as a feature quantity of the signal used for suppressing the interference signal superimposed on the desired signal from the received signal. It is possible to avoid using the feature amount by mistake.
- the method further includes a detection step of detecting a preamble signal including a symbol of a signal waveform having a predetermined pattern from a signal arriving at the own station, wherein the identification step is performed in the detection step. If the preamble signal cannot be detected, the transmission source that transmitted the incoming signal may be identified as the transmission source to be suppressed.
- the receiving station cannot detect a preamble signal from a radio packet signal transmitted by a radio station belonging to a network different from the standard of the network to which the station belongs and a radio wave radiated by an electronic device such as a microwave oven. . Transmission of radio packet signals from radio stations belonging to networks of different standards and emission of radio waves by electronic devices such as microwave ovens are performed independently of transmission from the transmission station. Therefore, according to this interference suppression method, it is possible to appropriately identify the transmission source of the signal arriving at the receiving station.
- a transmission source identifier indicating a transmission source of each signal that has previously arrived at the own station.
- a list creation step for creating an enumerated first peripheral terminal list, and a list for obtaining from the transmitting station a second peripheral terminal list enumerating a transmission source identifier indicating a transmission source of each signal that has previously arrived at the transmitting station.
- An acquisition step wherein the identifying step is based on the first peripheral terminal list and the second peripheral terminal list, and the transmission source that has transmitted the signal that has arrived at the local station is a transmission that is not subject to suppression.
- the identification step uses transmission source identifiers listed in both the first peripheral terminal list and the second peripheral terminal list as transmission sources not to be suppressed. You may make it identify.
- the identification step includes a transmission source of a transmission source identifier that is listed in the first peripheral terminal list but is not listed in the second peripheral terminal list. You may make it identify.
- the signal source that is a radio station that includes the transmitting station in the radio wave reachable range There is no overlap between the transmission period and the transmission period of the transmitting station.
- the transmission period of the signal source which is a radio station that does not include the transmitting station in the radio wave coverage, and the transmission period of the transmitting station overlap. From this, the transmission source of each signal arriving at the receiving station out of the transmission source of each signal arriving at the receiving station can transmit the interference signal superimposed on the desired signal based on the transmission of the transmitting station at the receiving station.
- the transmission sources other than the transmission sources of the signals arriving at the transmitting station transmit an interference signal superimposed on the desired signal based on the transmission of the transmitting station at the receiving station.
- this interference suppression method it is possible to appropriately identify the transmission source of the signal arriving at the receiving station.
- the list acquisition step receives a signal including the content of the second peripheral terminal list transmitted from the transmitting station, and determines the content of the second peripheral terminal list from the signal. You may make it read.
- the list acquisition step includes: a list request step for transmitting a request signal for requesting the second peripheral terminal list to the transmitting station; and the request signal transmitted in the list request step.
- a response signal including the contents of the second peripheral terminal list may be received as a response to, and the contents of the second peripheral terminal list may be read from the response signal.
- the list requesting step may be performed by transmitting the request signal by continuously transmitting two CTS (Clear To Send) frames to the transmitting station. Good. According to these, it is possible to provide a simple mechanism for the receiving station to obtain the second peripheral terminal list from the transmitting station.
- CTS Car To Send
- FIG. 1 is a system configuration diagram of a wireless communication system according to a first embodiment.
- FIG. 2 is a diagram showing a frame format of a wireless packet signal transmitted and received between the wireless stations in FIG.
- FIG. 3 is a device configuration diagram of the radio station of FIG. 1.
- FIG. 4 is a diagram showing an example of the contents stored in the feature amount storage unit of FIG.
- FIG. 5 is a device configuration diagram of the signal detection unit of FIG.
- FIG. 6 is a device configuration diagram of the interference suppression unit in FIG. 3.
- FIG. 7 is a flowchart showing the flow of interference measurement processing and interference suppression processing performed by the radio station of FIG.
- FIG. 8 is a flowchart showing a flow of suppression target identification processing performed by the wireless station of FIG.
- FIG. 9 is a diagram for explaining an operation example of reception processing performed by the wireless station in FIG. 1.
- FIG. 10 is a system configuration diagram of a wireless communication system according to a second embodiment.
- FIG. 11 is a diagram showing a frame format of an RTI request frame and an RTI response frame transmitted / received between the wireless stations in FIG.
- FIG. 12 is a device configuration diagram of the radio station of FIG.
- FIG. 13 is a diagram showing an example of the contents stored in the terminal list storage unit of FIG.
- FIG. 14 is a diagram showing an example of storage contents of a feature amount storage unit of FIG.
- FIG. 15 is a flowchart showing the flow of interference measurement processing and interference suppression processing performed by the radio station of FIG.
- FIG. 16 is a flowchart showing a flow of suppression target identification processing performed by the wireless station of FIG.
- FIG. 17 shows an example of a procedure for the wireless station in FIG. 10 to exchange a peripheral terminal list with another wireless station.
- FIG. 18 is a diagram showing an example of reception processing at the time of feature amount measurement performed by the wireless station of FIG.
- FIG. 19 is a diagram showing an example of reception processing when interference suppression is performed by the wireless station in FIG.
- FIG. 20 is a diagram for explaining another procedure for the wireless station in FIG. 12 to exchange a peripheral terminal list with another wireless station.
- FIG. 21 A diagram showing another example of the contents stored in the terminal list storage unit of FIG.
- FIG. 23 A diagram showing another example of the reception process at the time of the feature amount measurement performed by the wireless station of FIG.
- FIG. 1 is a system configuration diagram of the radio communication system according to the present embodiment.
- the basic service set (Basic Service Set) is shown as Basic Service Set (BSS) 1 and BSS2.
- BSS1 includes an access point API and a plurality of radio stations la, lb, lc, and Id.
- Radio station 1 The MAC header of a radio packet signal based on transmission of a, lb, etc. includes BSSID (Basic Service Set Identification).
- BSSID is the MAC (Media Access Control) address of the access point API.
- BSS2 includes an access point AP2 and a plurality of radio stations 2a and 2b.
- the BSSID is included in the MAC header of radio packet signals based on transmissions such as radio stations 2a and 2b.
- the BSSID is the MAC address of access point AP2.
- the access point API in BSS1 and access point AP2 in BSS2 are connected to the backbone network.
- radio station la is described as a transmitting station, radio station lb as a receiving station, and other radio stations lc, Id, 2a, and 2b as interfering stations.
- the receiving station lb mainly (1) whether or not the timing at which the received signal is received is a transmission prohibition period, which will be described later, or (2) whether or not the received signal power preamble signal has been detected. (3) Based on whether the BSSID used by the own station matches the BSSID in the MAC header of the received signal, the transmission source that transmitted the received signal is superimposed on the desired signal based on the transmission of the transmitting station la. Distinguish between interference sources that may transmit interference signals (hereinafter referred to as transmission sources to be suppressed) and interference sources that have no possibility (hereinafter referred to as transmission sources that are not to be suppressed).
- the receiving station lb since the interfering stations lc and Id belong to the same BSS1 as the receiving station lb, the receiving station lb has the BSSID used by itself and the BSSID of the MAC header of the received signal received from the interfering stations lc and Id.
- the interference stations lc and Id are identified as non-suppressed transmission sources.
- the receiving station lb since the interfering stations 2a and 2b belong to BSS2 different from the BSS1 to which the receiving station lb belongs, the receiving station lb includes the BSSID used by the own station and the BSSID of the MAC header of the received signal received from the interfering stations 2a and 2b. And the interfering stations 2a and 2b are identified as the transmission sources to be suppressed.
- the receiving station lb selects one transmission source from among the transmission sources identified as the transmission source to be suppressed, and a signal corresponding to the selected transmission source.
- the interference signal is suppressed from the received signal using the feature quantity of.
- the feature quantity of the interference signal used when suppressing the interference signal from the received signal is It is selected only from transmission sources that are subject to suppression, and not selected from transmission sources that are not subject to suppression.
- the channel frequency of radio communication between the transmitting station la and the receiving station lb is the same as the channel frequency of radio communication between the interfering stations lc and 2a and the interfering stations ld and 2b.
- the channel interference will be described as an object.
- FIG. 2 is a diagram showing a frame format of a radio bucket signal transmitted / received between the radio stations in FIG.
- the radio packet signal includes a preamble signal 6 and a subsequent data symbol string 7 as shown in FIG. 2 (a).
- the preamble signal 6 is used for synchronization detection and propagation path estimation.
- the preamble signal includes 10 short training symbols and 2 long training symbols.
- the data symbol string 7 includes a PHY header 7a and a MAC header 7b.
- the PHY header 7a includes modulation parameter and data length information of each subsequent data symbol.
- the MAC header 7b includes a destination address 7A, a source address 7B, and a BSSID 7C, and includes control information (not shown).
- the destination address 7A stores the MAC address of the receiving radio station
- the source address 7B stores the MAC address of the transmitting radio station.
- BSSID7C also stores the MAC address of the BSS access point to which the transmitting wireless station belongs.
- each data symbol included in the data symbol sequence 7 is modulated by a modulation method called OFDM (Orthogonal Frequency Division Multiplexing).
- OFDM Orthogonal Frequency Division Multiplexing
- FIG. Fig. 3 is a block diagram of the radio station lb. Note that the radio station la and the like other than the radio station lb have the same device configuration as that of the radio station lb and will not be described.
- the radio station lb includes a plurality of antennas 11—1,..., Ll_k, a switch circuit 12, an RF unit 13 1,.
- a target identification unit 15, a feature amount storage unit 16, an interference suppression unit 17, a MAC (Media Access Control) control unit 18, a modulation unit 19, and an RF unit 20 are provided.
- the antenna 11_1 is used as an antenna for transmission and reception, and is connected to the RF unit 20 at the time of transmission by the switch circuit 20, and is connected to the RF unit 13_1 at times other than the transmission.
- RF sections 13-1,..., 13 _k down-convert high frequency band signals (hereinafter referred to as RF signals) input from antennas 11— 1,.
- a baseband signal (hereinafter referred to as a baseband signal) is output to the signal detection unit 14 and the interference suppression unit 17.
- the signal detection unit 14 Based on the baseband signals input from the RF units 13-1,..., 13-k, the signal detection unit 14 confirms that the signal has arrived and that the arrival of the signal that has arrived has ended. To detect.
- the signal detection unit 14 outputs an arrival notification signal and an arrival end notification signal to the suppression target identification unit 15 based on the detection result.
- the signal detection unit 14 When the arrival of the signal is detected, the signal detection unit 14 further performs a preamble signal detection process from the received signal. If the preamble signal can be detected, the signal detection unit 14 determines that there is a possibility of the desired signal and detects the preamble signal. If not, it is judged that there is no possibility of a desired signal. The signal detection unit 14 outputs a type notification signal indicating the determination result to the suppression target identification unit 15.
- the preamble signal detection process is performed as follows, for example.
- the preamble signal repeatedly includes training symbols of a signal waveform having a predetermined pattern.
- the signal detector 14 sequentially obtains a correlation value between the baseband signal and the reference signal (a signal having the same signal waveform as the training symbol on the transmission side), and if the peak of the correlation value appears in the repetition cycle of the training symbol, It is determined that the signal has been detected.
- the signal detector 14 estimates the symbol timing using the correlation value peak, and calculates the estimated symbol type. Is output to the interference suppression unit 17.
- the suppression target identification unit 15 determines that the transmission source that transmitted the received signal is the transmission source that is not the suppression target and the transmission source that is the suppression target. To identify.
- the suppression target identification unit 15 mainly selects (A) when the timing at which the signal is received is a transmission prohibited period, (B) when the received signal power is too strong to detect the preamble signal, If the BSSID does not match the BSSID in the MAC header of the received signal, it is determined that the transmission source that transmitted the received signal is the transmission source to be suppressed. In other cases, the suppression target identification unit 15 determines that the transmission source that transmitted the received signal is a transmission source that is not the suppression target.
- the suppression target identification unit 15 performs update control of the storage content of the feature amount storage unit 16.
- the transmission target feature quantity of the received signal has been previously determined to be the transmission source of the suppression target. If it is similar to the feature quantity of the signal received from the source, it is determined that the transmission source that transmitted the received signal is the transmission source to be suppressed.
- the transmission prohibition period is, for example, SIFS determined by the IEEE 802.1 la standard or the like.
- the feature amount storage unit 16 is a storage unit for storing the feature amount of each subband of the interference signal for each transmission source to be suppressed.
- the feature amount storage unit 16 temporarily stores the feature amount of the signal being received input from the interference suppression unit 17 and also stores the feature amount of the signal input from the interference suppression unit 17 as a suppression target identification unit 15. Output to.
- the feature quantity storage unit 16 is controlled by the suppression target identification unit 15 and discards the feature quantity of the signal input from the interference suppression unit 17 or updates the stored content based on the feature quantity of the signal.
- the feature amount storage unit 16 interferes with the stored feature amount of the signal related to one transmission source. Output to suppression unit 17.
- the feature quantity storage unit 16 stores a feature quantity management table shown in FIG. 4 as an example.
- the feature quantity management table includes “No.” and “feature quantity” as fields.
- the field “feature” includes subfields “subband 1”, “subband 2”, “subband 3”, “subband 4”, and “subband 5”.
- the field "No.” stores a number
- the subfield "subband 1" and the like of the field "feature” store the subband feature of the interference signal measured by the interference suppression unit 17.
- the feature quantity stored in the feature quantity management table is only the feature quantity of the interference signal previously transmitted by the transmission source determined by the suppression target identifying unit 15 as the transmission source to be suppressed.
- the feature quantity management table does not store a feature quantity related to a transmission source determined by the suppression target identification unit 15 to be a transmission source that is not a suppression target.
- the interference suppression unit 17 has two operation modes of “interference measurement mode” and “interference suppression mode”, and is controlled by the MAC control unit 18 to switch the operation mode.
- the interference suppression unit 17 When operating in the “interference measurement mode”, the interference suppression unit 17 measures the feature quantity of the baseband signal input from the RF units 13-1,..., 13-k, and features the measured feature quantity. Output to quantity storage unit 16. Further, the interference suppression unit 17 performs demodulation processing on the baseband signal received by the single antenna or the baseband signal subjected to the maximum ratio combining and outputs the demodulated data to the MAC control unit 18.
- the interference suppression unit 17 When operating in the "interference suppression mode", the interference suppression unit 17 is input from the RF units 13-1, ..., 13_k based on the feature values input from the feature value storage unit 16. Interference suppression processing is performed to suppress the interference signal from the baseband signal, and then demodulation processing is performed and demodulated data is output to the MAC control unit 18.
- the interference suppression unit 17 performs measurement of the characteristic amount of the baseband signal and suppression of the baseband signal force interference signal in units of subbands.
- the MAC control unit 18 instructs the interference suppression unit 17 to switch the operation mode.
- the operation mode of the interference suppression unit 17 is controlled by outputting the control signal.
- the MAC control unit 18 determines that the BSS ID of the MAC header of the demodulated data input from the interference suppression unit 17 matches the BSSID used by the local station, the MAC control unit 18 switches to the interference suppression mode for the interference suppression unit 17. A control signal for instructing switching is output. After that, when the input from the interference suppression unit 17 of the demodulated data whose BSSID in the MAC header matches the BSSID used by the own station is completed, the MAC control unit 18 instructs the interference suppression unit 17 to enter the “interference measurement mode”. A control signal for instructing switching is output.
- the interference suppression unit 17 determines that the BSSID of the MAC header of the demodulated data matches the BSSID of the own station, and then determines the source of the demodulated data. It operates in the “interference suppression mode” during the period until the arrival of the received signal that has become, and operates in the “interference measurement mode” during other periods.
- the MAC control unit 18 outputs to the suppression target identification unit 15 a transmission prohibition period notification signal indicating whether it is currently in the transmission prohibition period or outside the transmission prohibition period, and also includes the MAC header of the demodulation data.
- the same network notification signal is output indicating whether the BSSID matches the BSSID used by the local station.
- Modulation section 19 modulates the transmission data input from MAC control section 18 using a predetermined modulation scheme.
- the RF unit 20 up-converts the modulated baseband signal input from the modulation unit 19.
- the RF signal obtained by the up-conversion is radiated from the antenna 111 through the switch circuit 12.
- FIG. 5 is a device configuration diagram of the signal detection unit 14 of FIG.
- the signal detection unit 14 includes subband separation units 31-1,..., 31_k and a subband combined signal detection unit 32.
- the subband separation unit 31-1 divides the baseband signal input from the RF unit 13-1 into subband signals of a plurality of subbands (for example, five), and each subband obtained by the division. Output to the sub-band combined signal detector 32.
- Subband separation unit 31 Subband separators 31-k other than 1 perform substantially the same processing as subband separator 31-k.
- FFT Fast Fourier Transform
- wavelet transform wavelet transform
- filter bank filter bank
- one subband separation unit may be used in a time division manner.
- the subband combined signal detection unit 32 combines the subband signals for each subband based on the subband signals input from the subband separation units 31-1, ..., 31_k.
- the subband combined signal detector 32 detects the amount of change such as the power value for each subband and the correlation between the subband signals (correlation between antennas), and the arrival of the signal and the signal that has arrived. It is detected that the arrival of has ended. Further, the subband combined signal detection unit 32 performs a preamble signal detection process for each subband, and determines whether or not the received signal may be a desired signal.
- the configuration of the signal detection unit 14 is not limited to that shown in FIG. 5, and may be a configuration that does not have a subband separation unit.
- the RF unit 13-1,..., 13_k detects the amount of change in the power value of the baseband signal and the correlation between the antennas, and the arrival of the signal. It may be detected that the arrival of the signal has ended. Further, the preamble signal may be detected for each baseband signal.
- FIG. 6 shows Figure 3.
- 2 is a device configuration diagram of the interference suppression unit 17 of FIG.
- Fig. 6 covers multicarrier modulation schemes such as the OFDM scheme as the modulation scheme.
- the interference suppression unit 17 shown in FIG. 6 is a technology (see International Publication No. 2006/003776 pamphlet) previously filed by the applicant.
- the interference suppression unit 17 includes subband separation units 51-1,..., 51-k, subband processing units 52-1,..., 52_h, and a demodulation unit 53.
- the number of subband processing units 52—1,..., 53_h is five, for example.
- the subband separation unit 51 _ 1 divides the baseband signal input from the RF unit 13-1 into a plurality of subband signals (here, “h”), and each subband signal obtained by the division is subdivided.
- the band signal is output to the sub-band processing unit 52—1,.
- the subband separation unit 51_k and the like other than the subband separation unit 51_1 perform substantially the same processing as the subband separation unit 51_1.
- one subband separation unit may be used in a time division manner.
- the sub-band processing unit 52—h combines the sub-band signals input from the sub-band separation units 51— 1,..., 51—k for each sub-band, and sets the baseband signal feature amount for each sub-band. Measurement and suppression of interference signals from baseband signals are performed.
- the subband processing units 52-1 and the like other than the subband processing unit 52-h perform substantially the same processing as the subband processing unit 52-h.
- Demodulation section 53 combines the signals input from subband processing sections 52-1,..., 52-h, demodulates the combined signals, and outputs the demodulated data to MAC control section 18.
- the subband processing unit 52-h includes a propagation path estimation unit 54-h, a feature amount measurement unit 55-h, and a weighting synthesis unit 56_h.
- the propagation path estimation unit 54_h performs propagation path estimation of the received signal based on the known signals included in the subband signals input from the subband separation units 51-1,..., 51_k. Is output to the weighted combining unit 56_h.
- the feature amount measuring unit 56—h is a sub-band separating unit 51—1 when operating in the “interference measurement mode”.
- ⁇ , 51— k is obtained as a covariance matrix Ruu, which is a correlation between subband signals input from k, and the obtained covariance matrix Ruu is used as a feature value of a subband of the baseband signal.
- the covariance matrix includes information on correlation between subband signals (correlation between antennas) and power values of subband signals.
- the weighted combining unit 56—h uses the propagation path estimation unit JH input from the propagation path estimation unit 54—h when operating in the “interference measurement mode”, and uses the subband separation unit 51. — Weights and synthesizes each subband signal input from 1, ⁇ , 51_k, and outputs the weighted signal to demodulator 53.
- the weighted combining unit 56 — h receives the subband signals from the subband separating units 51-1,..., 51 — k. All input subband signals are represented by one matrix (hereinafter referred to as subband matrix) r.
- the weighting combining unit 56_h uses the propagation path estimation matrix H input from the propagation path estimation unit 54_h and the feature quantity (covariance matrix Ruu) input from the feature quantity storage section 16, and uses the following equation (1 ) To perform weighted synthesis of the subband signal and output the signal V with the interference signal component suppressed to the demodulator 53.
- H * is the complex conjugate transpose of H
- (HRssH * + Ruu) _ 1 shows the inverse matrix of (HRssH * + Ruu).
- ijRss represents the covariance matrix of the signal s sent from the transmitting station, and can know the statistical power of the transmitted signal.
- FIG. 7 is a flowchart showing the flow of interference measurement processing and interference suppression processing performed by the radio station lb.
- the MAC control unit 18 performs control for setting the operation mode of the interference suppression unit 17 to the “interference measurement mode” (step Sl l).
- the interference suppression unit 17 sets the operation mode to “interference measurement mode”, measures the characteristic amount of the baseband signal input from the RF units 13-1,..., 13_k, and demodulates the baseband signal.
- the demodulated data is output to the MAC controller 18 (step S12).
- the MAC control unit 18 performs a MAC header acquisition process from the demodulated data input from the interference suppression unit 17 (step S 13). Until the MAC header is acquired (step S13: NO), the MAC control unit 18 performs the MAC header acquisition process with demodulated data.
- the MAC control unit 18 compares the BSSID in the MAC header with the BSSID used by the own station (step S14).
- step S14 determines that the desired signal is not included in the received signal (step S15), and performs the processing of step S12.
- the interference suppression unit 17 continuously measures the feature quantity of the baseband signal input from the RF units 13-1,..., 13_k.
- step S14 YES
- the MAC control unit 18 determines that there is a possibility that the desired signal is included in the received signal (step S16).
- the MAC control unit 18 performs control for switching the operation mode of the interference suppression unit 17 to the “interference suppression mode” (step S17). As a result, the interference suppression unit 17 switches the operation mode from the “interference measurement mode” to the “interference suppression mode”.
- the feature quantity storage unit 16 outputs the stored feature quantity of one transmission source to the interference suppression unit 17.
- the interference suppression unit 17 suppresses the interference signal based on the feature amount input from the baseband signal input from the RF unit 13-1,..., 13-k, and further demodulates the baseband signal.
- the demodulated data is output to the MAC controller 18 (step S18).
- the MAC control unit 18 determines whether the arrival of the signal being received has ended based on the data length in the demodulated data (step S19).
- step S 19 If the signal being received continues and arrives (step S 19: NO), the process returns to step S 18 and the interference suppression unit 17 starts from the RF unit 13-1,. Continue to suppress interference signals from the input baseband signal.
- step S19 If the arrival of the signal being received has ended (step S19: YES), the processing returns to step S11, and the MAC control unit 18 sets the operation mode of the interference suppression unit 17 to "interference measurement mode”. The interference suppression unit 17 starts the operation of “interference measurement mode”.
- FIG. 8 is a flowchart showing the flow of suppression object identification processing performed by the wireless station lb.
- the signal detection unit 14 performs signal arrival detection processing based on the baseband signal, and the suppression target identification unit 15 receives the signal arrival power based on the arrival notification signal from the signal detection unit 14, Is determined (step S31).
- step S32 If the suppression target identification unit 15 receives the arrival notification signal from the signal detection unit 14 and determines that the signal has arrived (step S31: YES), the processing of step S32 is performed.
- the MAC control unit 18 currently determines whether it is in the transmission prohibition period or outside the transmission prohibition period, and outputs a transmission prohibition period notification signal indicating the determination result to the suppression target identification unit 15. . Based on the transmission prohibition period notification signal input from the MAC control unit 18, the suppression target identification unit 15 determines whether or not the timing at which the arrival notification signal is input from the signal detection unit 14 is within the transmission prohibition period. (Step S32).
- the suppression target identification unit 15 determines that the signal being received is the signal to be suppressed, and transmits the signal.
- the source is determined to be the transmission source to be suppressed (step S33).
- the suppression target identifying unit 15 converts the feature amount of the signal being received input from the feature amount storage unit 16 within the measurement band to the feature amount stored in the feature amount management table of the feature amount storage unit 16. It is determined whether they are similar to any one (step S34).
- the similarity between the two features is determined using the correlation between antennas and the time characteristics of power fluctuations included in the covariance matrix as information. If the added value of the difference in correlation between the two antennas is less than or equal to the predetermined value, it is determined that the correlation between the two antennas is similar, and the added value of the difference between the sampling points of the time characteristics of both power fluctuations If it is below, it is judged that the time fluctuations of both power fluctuations are similar. Then, when both the correlation between antennas and the power fluctuation are similar, it is determined that the feature amounts are similar. It should be noted that the mechanism for determining the similarity between both feature quantities is not limited to the above.
- step S34 If the feature quantity of the signal being received is stored in the feature quantity management table of the feature quantity storage unit 16 and is similar to any one of the feature quantities (step S34: YES), the suppression target identification unit 15 Determines that the transmission source of the signal being received is one of suppression target transmission sources already stored in the feature quantity management table of the feature quantity storage unit 16. Then, the suppression target identification unit 15 updates the feature quantity stored in the feature quantity management table of the feature quantity storage unit 16 that is similar to the feature quantity of the signal being received to the feature quantity of the signal being received. (Step S35). Then, the processing after step S31 is performed.
- step S34 If the feature amount of the signal being received is not similar to any feature amount stored in the feature amount management table of the feature amount storage unit 16 (step S34: NO), the suppression target identifying unit 15 determines that the transmission source of the signal being received is a new transmission source to be suppressed. Then, the suppression target identification unit 15 newly registers the feature amount of the signal being received in the feature amount management table of the feature amount storage unit 16 (step S36). Then, the processing after step S31 is performed.
- the signal detection unit 14 After detecting the arrival of the signal, the signal detection unit 14 performs a preamble signal detection process from the received signal, and outputs a type notification signal to the suppression target identification unit 15 based on the detection result.
- the suppression target identification unit 15 determines whether a preamble signal is detected based on the type notification signal (step S37).
- the suppression target identification unit 15 determines that the signal being received is a signal to be suppressed, and determines that the transmission source of the signal is a transmission source to be suppressed (step S33). Then, the processing after step S34 is performed.
- the suppression target identification unit 15 uses the feature quantity of the signal being received input from the feature quantity storage unit 16 outside the signal band as the feature quantity. It is determined whether it is similar to any of the feature quantities stored in the feature quantity management table of the storage unit 16 (step S38).
- the suppression target identifying unit 15 determines that the signal being received is the signal to be suppressed, and the transmission source of the signal is the transmission to be suppressed. Is determined to be a source (step S39). Then, the suppression target identification unit 15 updates the feature amount stored in the feature amount management table of the feature amount storage unit 16 similar to the feature amount of the signal being received to the feature amount of the signal being received ( Step S40). Then, the processing after step S31 is performed.
- the interference suppression unit 17 Performs demodulation processing based on the baseband signal input from the RF unit 13-1, ..., 13_k, and outputs the demodulated data to the MAC control unit 18 (step S41).
- the MAC control unit 18 determines whether or not the PHY header in the demodulated data input from the interference suppression unit 17 is normal, and outputs the determination result to the suppression target identification unit 15.
- the suppression target identification unit 15 determines whether the PHY header is normal based on the determination result input from the MAC control unit 18 (step S42).
- step S42 If the PHY header is normal (step S42: YES), the process of step S43 is performed.
- the MAC control unit 18 compares the BSSID in the MAC header of the demodulated data with the BSSID used by the own station, and outputs the same network notification signal indicating the comparison result to the suppression target identification unit 15. Based on the same network notification signal, the suppression target identification unit 15 determines whether both BSSIDs match (step S43).
- step S43 If both BSSIDs match (step S43: YES), the suppression target identification unit 15 determines that the signal being received is a signal not to be suppressed, and the transmission source of the signal is not to be suppressed. Judged as the transmission source. Then, the suppression target identification unit 15 causes the feature amount storage unit 16 to discard the feature amount of the temporarily stored signal (step S44). Then, the processing after step S31 is performed.
- step S43 NO
- the suppression target identification unit 15 determines that the signal being received is the signal to be suppressed, and the transmission source of the signal is the transmission source to be suppressed. (Step S33). Then, the processing after step S34 is performed.
- the suppression target identification unit 15 determines whether the power outside the signal band is larger than the power within the signal band (step S45). [0083] If the power outside the signal band is greater than the power within the signal band (step S45: YES), the suppression target identification unit 15 determines that an interference signal has arrived in the adjacent channel, for example. to decide. The suppression target identifying unit 15 determines that the signal being received is a signal to be suppressed, and determines that the transmission source of the signal is the transmission source to be suppressed (step S33). Then, the processing after step S34 is performed.
- step S45 NO
- the suppression target identification unit 15 has, for example, low power within the signal band. It is determined that an error has occurred in demodulation of the P HY header. Then, the suppression target identification unit 15 causes the feature amount storage unit 16 to discard the feature amount of the temporarily stored signal. Then, the processing after step S31 is performed.
- FIG. 9 is a diagram for explaining an operation example of reception processing performed by the wireless station lb of FIG.
- the interfering station 2a transmits the first signal addressed to the interfering station 2b at time ijtl1
- the interfering station 2b receives the first signal
- the receiving station lb also receives the first signal.
- the signal detection unit 14 of the receiving station lb detects the arrival of a signal due to an increase in received power or the like, and detects a preamble signal from the signal being received.
- the MAC control unit 18 determines that the PH header of the signal being received is normal, and determines that the BSSID in the MAC header does not match the BSSID used by the own station.
- the suppression target identification unit 15 determines that the signal being received is the signal to be suppressed, and determines that the transmission source of the signal is the transmission source to be suppressed. Then, the suppression target identification unit 15 newly registers the feature amount of the signal being received measured by the interference suppression unit 17 in the feature amount storage unit 16.
- the signal detector 14 of the receiving station lb detects the arrival of a new signal due to an increase in received power or the like, and detects the preamble signal from the signal being received.
- MAC controller 18 It is determined that the PHY header of the signal being received is normal, and it is determined that the BSSID in the MAC header matches the BSSID used by the local station.
- the MAC control unit 18 performs control for switching the operation mode of the interference suppression unit 17 to the “interference suppression mode”.
- the interference suppression unit 17 suppresses the interference signal based on the feature amount input from the feature amount storage unit 16 from the signal being received.
- the transmission source that has transmitted the signal being received based on the reception timing of the signal received by the receiving station, the BSSID of the MAC header, or the like is used as the transmission source to be suppressed and the transmission not to be suppressed. Identify with source.
- the reception source transmits a signal received by comparing the transmission source that transmitted each signal previously received with the transmission source that transmitted the signal previously received by the transmission station.
- the transmission source that transmitted each signal previously received by the station is identified as a transmission source to be suppressed and a transmission source not to be suppressed.
- FIG. 10 is a system configuration diagram of the radio communication system according to the present embodiment.
- FIG. 10 shows the non-fountain stations 3a, 3b, 3c, 3d, 4a, 4b force S, and the non-fountain stations 3b, 3c, 3d are located within the radio wave coverage of the radio station 3a. However, radio stations 4a and 4b are located outside the radio signal range of radio station 3a. It is assumed that the radio station reach is the same for all radio stations.
- the wireless stations 3b, 3c, and 3d located within the radio wave coverage of the wireless station 3a are wireless during the period when the wireless station 3a transmits the wireless packet signal. A packet signal is not transmitted.
- the radio stations 4a and 4b outside the radio wave reach of the radio station 3a perform carrier sense. However, since the wireless packet signal transmitted by the wireless station 3a cannot be detected, the wireless stations 4a and 4b may transmit the wireless packet signal while the wireless station 3a is transmitting the wireless packet signal.
- the wireless station 3a is a transmitting station
- the wireless station 3b is a receiving station
- the other wireless stations 3c, 3d, 4a, and 4b are interference stations.
- the receiving station 3b receives the wireless packet signals previously transmitted by the transmitting station 3a and the interfering stations 3c, 3d, 4a, 4b, and receives the MAC of the transmitting station 3a and the interfering stations 3c, 3d, 4a, 4b.
- the first peripheral terminal list that lists the addresses is stored internally.
- the transmitting station 3b previously received the wireless packet signals transmitted by the receiving station 3b and the interfering stations 3c and 3d, and the second peripheral terminal list listing the MAC addresses of the receiving station 3b and the interfering stations 3c and 3d. Is stored internally.
- the receiving station 3b obtains the second peripheral terminal list from the transmitting station 3a based on the RTI request packet or the RTI response packet, which will be described later, as shown in FIG. Compare with peripheral device list.
- the receiving station 3b is an interference station 3c, which is a wireless station listed in the second peripheral terminal list obtained from the transmitting station among the wireless stations (excluding the transmitting station) listed in the first peripheral terminal list.
- 3d is identified as a transmission source that is not subject to suppression, and interference stations 4a and 4b that are not listed radio stations are identified as transmission sources that are subject to suppression.
- the receiving station 3b selects one transmission source from among the transmission sources identified as the transmission source to be suppressed, and a signal corresponding to the selected transmission source.
- the interference signal is suppressed from the received signal using the feature quantity of.
- the feature quantity of the interference signal used when suppressing the interference signal from the received signal is selected only from the transmission source to be suppressed, and not selected from the transmission source not to be suppressed.
- the probability that the feature quantity of the signal used to suppress the interference signal from the received signal is the feature quantity of the interference signal actually superimposed on the desired signal is increased, and the received signal force interference is effectively prevented. It becomes possible to suppress the signal.
- FIG. 4 is a diagram showing a frame format of an RTI request frame and an RTI response frame transmitted / received by the network.
- the RTI request frame and the RTI response frame 8 include a MAC header 8a, an NRT 8b, and an RTI 8c.
- the MAC header 8a includes a destination address and a source address.
- NRT (Number of Recognizable Terminals) 8b is a field for storing the total number of MAC addresses of the transmitting station and receiving station of each signal arriving at the local station. The same MAC address is counted as one.
- RTI Recognition Call Identity 8c is a field for storing address 8A, HTP8B, RSSI8C, and RB8D for each radio station (transmitting station and receiving station of each signal that has arrived at its own station). .
- Address 8A is a field for storing the MAC address of the wireless station.
- HTP (Hidden Terminal Possiblity) 8B is a field for storing information indicating the possibility of a hidden terminal of a wireless station whose MAC address is stored in the corresponding address 8A. If the wireless station eavesdrops on the exchange of signals between neighboring wireless stations, receives only the response request signal, and fails to receive the response signal for the response request signal, the wireless station at the destination address of the response request signal Determines that there is a possibility of a hidden terminal. Then, “1” is stored in the HTP8B for the radio station that may be a hidden terminal. The other radio stations have no possibility of a hidden terminal, and “0” is stored in HTP8B. However, as a technique for recognizing the possibility of a hidden terminal, for example, there is a technique disclosed in Japanese Patent Laid-Open No. 2002-217913.
- RSSI (Received Signal Strength Indication) 8C is a final for storing the received power value of the received signal received from the radio station having the MAC address stored in the corresponding address 8A.
- the value stored in RSSI8C is not particularly used.
- RB (Required Bandwidth) 8D stores the required bandwidth included in the exchange if the frame including the QoS (Quality of Service) condition has been exchanged with the radio station whose MAC address is stored in the corresponding address 8A. It is a field to do. In addition, this implementation In the form, the value stored in RB8D is not particularly used.
- the total number of MAC addresses (total number of peripheral terminals) of the transmitting station (peripheral terminal) of each signal arriving at its own station is stored in NRT 8b.
- Predetermined information 8-1 is provided for each peripheral terminal, and the MAC address of the peripheral terminal is stored in address 8A and "0" is stored in HTP8B.
- FIG. 12 is a device configuration diagram of the radio station 3b. Note that the radio stations 3a and the like other than the radio station 3b have the same device configuration as the radio station 3b, and a description thereof will be omitted.
- the radio station 3b includes a plurality of antennas 11—1,..., Ll_k, a switch circuit 12, an RF unit 13_1,..., 13_k, a signal detection unit 14, and an object to be suppressed.
- An identification unit 15a, a terminal list storage unit 25, a feature amount storage unit 16a, an interference suppression unit 17, a MAC control unit 18a, a modulation unit 19, and an RF unit 20 are provided.
- the terminal list storage unit 25 stores a terminal list management table shown as an example in FIG.
- the terminal list management table includes “peripheral terminal address”, “peripheral terminal list”, “non-suppression terminal list”, and “suppression target terminal list” as fields.
- the field "Peripheral terminal address” stores the MAC address of the own station and the MAC address of the peripheral terminal one by one. Note that the MAC address of the peripheral terminal stored in the field “Peripheral terminal address” is the source address of the MAC header of the signal that the station previously received, that is, the MAC address of the wireless station that transmitted the signal. is there.
- the field “peripheral terminal list” stores the source address of the MAC header of each signal previously received by the wireless station having the corresponding peripheral terminal address. However, if the wireless station with the corresponding peripheral terminal address has previously received signals transmitted by multiple wireless stations, multiple MAC addresses are stored in the field “peripheral terminal list”.
- non-suppression target terminal list when the local station performs wireless communication with the wireless station with the corresponding peripheral terminal address and receives a signal from the wireless station, the local station superimposes this signal on this signal.
- the MAC address of the wireless station that has no possibility of transmitting the interference signal is stored.
- multiple MAC addresses are stored in the field “Non-suppression Terminal List”. There is power.
- the local station when the local station performs radio communication with the radio station of the corresponding peripheral terminal address and receives a signal from the radio station, the local station transmits an interference signal superimposed on this signal.
- the terminal list storage unit 25 performs suppression that lists the MAC addresses stored in the field "suppression target terminal list" of the record in which the MAC address of the transmission partner of the communication partner is stored in the finale "peripheral terminal address"
- the target terminal list is output to the feature amount storage unit 16a.
- the suppression target identification unit 15a and the stored contents of the record field “non-suppression terminal list” are stored with the MAC address of the local station. It is updated based on the contents stored in the record field “Peripheral terminal list” (first peripheral terminal list).
- the suppression target identification unit 15a lists the stored contents of the update target record field "non-suppression target terminal list" in the second peripheral terminal list among the peripheral terminal addresses listed in the first peripheral terminal list. Update to the peripheral terminal address. In addition, the suppression target identification unit 15a stores the contents stored in the field “suppression target terminal list” of the record to be updated in the peripheral terminal addresses listed in the first peripheral terminal list (excluding the peripheral terminal addresses of the record to be updated). ), Update the peripheral terminal addresses to those other than the peripheral terminal addresses listed in the second peripheral terminal list.
- the suppression target identification unit 15a reads the field “peripheral terminal list” of the record in which the field “peripheral terminal address” is the peripheral terminal address “R (local station)” and also reads the first peripheral terminal list S, A, B, C ”. Then, the second peripheral terminal list “R, C” is read from the field “peripheral terminal list” of the record to be updated. [0107]
- the suppression target identification unit 15a stores the contents of the update target record field "non-suppression target terminal list" in the second peripheral terminal list 'S, A, B, C'. Update the peripheral terminal address "C" in "R, C".
- the suppression target identification unit 15a changes the storage contents of the field “suppression target terminal list” of the record to be updated from the first peripheral terminal list S, A, B, C ”to the peripheral terminal address“ S ”of the record to be updated. Of “A, B, C” excluding, the peripheral terminal addresses “A, B” except for the peripheral terminal address “C” in the second peripheral terminal “R, C” are updated.
- the feature amount storage unit 16a is a storage unit for storing the feature amount of the interference signal for each wireless terminal that has transmitted a signal received by the own station, that is, for each peripheral terminal.
- the feature quantity of the interference signal of one radio station listed in the suppression target terminal list input from the unit 25 is output to the interference suppression unit 17.
- a feature quantity management table shown in FIG. 14 is stored in the feature quantity storage unit 16a.
- the feature quantity management table includes “peripheral terminal address” and “feature quantity” as fields.
- the field “feature” includes subfields “subband 1”, “subband 2”, “subband 3”, “subband 4”, and “subband 5”.
- peripheral terminal address In the field “peripheral terminal address”, the MAC addresses of the peripheral terminals are stored one by one.
- the MAC address of the peripheral terminal stored in the field “peripheral terminal address” is the transmission source address of the MAC header of the signal received by the local station before.
- the subfield “subband 1”, etc. of the field “feature” stores the subband feature of the interference signal related to the corresponding radio station measured by the interference suppression unit 17.
- the feature amount storage unit 16a receives the suppression target terminal list "A, B” from the terminal list storage unit 25.
- the feature quantity storage unit 16a selects one from the suppression target terminal list “A, B”, and outputs the feature quantity of the selected peripheral terminal address to the interference suppression unit 17.
- the MAC control unit 18a reads the PHY header and the MAC header from the demodulated data, and outputs the source address of the MAC header to the feature amount storage unit 16a and the terminal list storage unit 25. [0111]
- the MAC control unit 18a controls the operation mode of the interference suppression unit 17 by outputting a control signal for instructing the interference suppression unit 17 to switch the operation mode.
- the MAC control unit 18a determines that the destination address of the MAC header of the demodulated data input from the interference suppression unit 17 matches the MAC address of its own station, the MAC control unit 18a notifies the interference suppression unit 17 of “interference suppression mode”. A control signal for instructing switching to is output. After that, when the input from the interference suppression unit 17 of the demodulated data whose destination address in the MAC header matches the MAC address of the own station is completed, the MAC control unit 18a sends the “interference measurement mode” to the interference suppression unit 17. A control signal for instructing switching to is output.
- the MAC control unit 18a performs an acquisition process for acquiring the second peripheral terminal list from the radio station of the communication partner, and outputs the acquired second peripheral terminal list to the terminal list storage unit 25.
- FIG. 15 is a flowchart showing the flow of interference measurement processing and interference suppression processing performed by the wireless station 3b of FIG. The same processing procedure is executed at the communication partner station (transmitting station 3a) that performs wireless communication with the wireless station 3b.
- the MAC control unit 18a performs control for setting the operation mode of the interference suppression unit 17 to the “interference measurement mode” (step S61).
- the interference suppression unit 17 sets the operation mode to the “interference measurement mode”, measures the characteristic amount of the baseband signal input from the RF units 13-1,... Demodulate and output the demodulated data to the MAC controller 18a (step S62).
- the MAC control unit 18a acquires a PHY header and a MAC header from the demodulated data input from the interference suppression unit 17 (step S63).
- the MAC control unit 18a compares the acquired destination address of the MAC header with its own MAC address (step S64).
- step S64 determines that the signal being received is an interference signal, and outputs the source address in the MAC header to the terminal list storage unit 24. (Step S65). [0115] Based on the data length in the demodulated data, the MAC control unit 18a determines whether the arrival of the signal being received has ended (step S66).
- step S66 If the signal being received continues to arrive (step S66: NO), the MAC control unit 18a continues the process of step S66.
- the terminal list storage unit 25 uses the field “peripheral terminal address” in the terminal list management table as the source address input from the MAC control unit 18a. If it is not registered in "", new registration is performed. The terminal list storage unit 25 stores the source address input from the MAC control unit 18a in the field “peripheral terminal list” of the record in which the peripheral terminal address in the field “peripheral terminal address” matches the MAC address of the local station. If not, add the source address (step S66: YES).
- the feature quantity storage unit 16a will display the field "feature” The stored content of “amount” is updated to the feature amount input from the interference measurement unit 17.
- the feature quantity storage unit 16a includes the source address input from the MAC control unit 18a and the feature quantity input from the interference suppression unit 17 in the fields “peripheral terminal address” and “feature quantity”. Is newly created (step S68).
- step S64 if the two match (step S64: YES), the MAC control unit 18a determines that the signal being received is the desired signal (step S69).
- the MAC control unit 18a performs control for switching the operation mode of the interference suppression unit 17 to the “interference suppression mode”. Thereby, the interference suppression unit 17 switches the operation mode from the “interference measurement mode” to the “interference suppression mode” (step S70).
- the terminal list storage unit 25 searches the terminal list management table for a record in which the stored content of the field “peripheral terminal address” matches the transmission source address input from the MAC control unit 18a. Then, the terminal list storage unit 25 outputs the suppression target terminal list stored in the field “suppression target terminal list” of the matched record to the feature amount storage unit 16a (step S71).
- the feature quantity storage unit 16a is arranged in the suppression target terminal list input from the terminal list storage unit 25. Select one MAC address from the listed MAC addresses. The feature amount storage unit 16a searches the feature amount management table for a record whose stored contents of the field “peripheral terminal address” match the selected MAC address. Then, the feature amount storage unit 16a outputs the feature amount stored in the field “feature amount” of the matched record to the interference suppression unit 17 (step S72).
- the interference suppression unit 17 suppresses the interference signal from the baseband signals input from the RF units 13-1,..., 13_k based on the feature values input from the feature value storage unit 16a.
- the demodulated signal is demodulated and the demodulated data is output to the MAC control unit 18a (step S73).
- the MAC control unit 18a determines whether the arrival of the signal being received has ended (step S74).
- step S74 If the signal being received continues to arrive (step S74: NO), the process returns to step S73, and the interference suppression unit 17 continues to suppress the interference signal from the baseband signal. Do.
- step S74 If the arrival of the signal being received has ended (step S74: YES), the process returns to step S61, and the MAC control unit 18a switches the operation mode of the interference suppression unit 17 to the “interference measurement mode”. The interference suppression unit 17 starts the operation of “interference measurement mode”.
- FIG. 16 is a flowchart showing the flow of suppression object identification processing performed by the wireless station 3b. The same processing procedure is executed in the communication partner station (transmitting station 3a) that performs wireless communication with the wireless station 3b.
- the MAC control unit 18a Since the MAC control unit 18a transmits the RTI request frame in a predetermined time unit, the MAC control unit 18a monitors the elapsed time and determines whether to transmit the RTI request frame (step S81).
- the MAC control unit 18a When the transmission of the RTI request frame is determined (step S81: YES), the MAC control unit 18a refers to the terminal list management table in the terminal list storage unit 25 and determines the peripheral terminal address of the field “peripheral terminal address”. The peripheral terminal list (first peripheral terminal list) in the field “Peripheral terminal list” of the record that matches the station MAC address is read. And MAC system The control unit 18a creates an RTI request frame that stores the first peripheral terminal list, and the generated RTI request frame is transmitted as a high-frequency signal via the RF unit 20, the switch circuit 12, and the antenna 11-1. (Step S82).
- the MAC control unit 18a determines whether an RTI response frame as a response to the RTI request frame transmitted in step S82 has been received from the communication partner station (step S83). Until the RTI response frame is received (step S83: NO), the MAC control unit 18a monitors the reception of the RTI response frame of the communication partner station.
- the RTI response frame contains the second peripheral terminal list of the communication partner station.
- the second peripheral terminal list is the field “peripheral terminal” of the record in which the peripheral terminal address of the field “peripheral terminal address” of the terminal list management table in the terminal list storage unit 25 of the communication partner station matches the MAC address of the communication partner station. This is a list of peripheral terminals in "List".
- step S83 When the RTI response frame is received (step S83: YES), the MAC control unit 18a reads the second peripheral terminal list from the RTI response frame (step S84).
- the MAC control unit 18a outputs the read second peripheral terminal list to the terminal list storage unit 25.
- the terminal list storage unit 25 stores the contents stored in the field “peripheral terminal list” of the field whose peripheral terminal address in the field “peripheral terminal address” of the terminal list management table matches the MAC address of the communication partner station. Update to list (step S85).
- the terminal list storage unit 25 outputs the first peripheral terminal list stored in the terminal list management table and the second peripheral terminal list input from the MAC control unit 18a to the suppression target identifying unit 15a.
- the suppression target identification unit 15a compares the first peripheral terminal list with the second peripheral terminal list (step S86).
- the suppression target identification unit 15a creates a non-suppression target terminal list of the communication partner station, and outputs it to the terminal list storage unit 25.
- the terminal list storage unit 25 suppresses the stored contents of the field “non-suppression target terminal list” of the record whose peripheral terminal address in the field “peripheral terminal address” of the terminal list management table matches the MAC address of the communication partner station. Update to the non-suppression target terminal list input from the target identification unit 15a (step S87)
- the suppression target identification unit 15a determines the suppression target terminal list of the communication partner station. And output to the terminal list storage unit 25.
- the terminal list storage unit 25 identifies the stored contents of the field “suppression target terminal list” of the record in which the peripheral terminal address in the field “peripheral terminal address” of the terminal list management table matches the MAC address of the communication partner station. Update to the suppression target terminal list input from the unit 15a (step S88).
- step S81 If it is determined in step S81 that the RTI request frame is not transmitted (step S81: NO), the MAC control unit 18a determines whether the communication partner station power is also the power of receiving the RTI request frame (step S81: NO). S89). If no RTI request frame has been received (step S89: NO), the process returns to step S81.
- step S89 YES
- the MAC control unit 18a reads the second peripheral terminal list from the RTI request frame (step S90).
- the MAC control unit 18a outputs the read second peripheral terminal list to the terminal list storage unit 25.
- the terminal list storage unit 25 stores the content stored in the field “peripheral terminal list” of the field whose peripheral terminal address in the field “peripheral terminal address” of the terminal list management table matches the MAC address of the communication partner station. Update to list contents (step S91) 0
- the terminal list storage unit 25 outputs the first peripheral terminal list stored in the terminal list management table and the second peripheral terminal list input from the MAC control unit 18a to the suppression target identifying unit 15a.
- the suppression target identification unit 15a compares the first peripheral terminal list with the second peripheral terminal list (step S92).
- the suppression target identification unit 15a creates a non-suppression target terminal list of the communication partner station, and outputs it to the terminal list storage unit 25.
- the terminal list storage unit 25 suppresses the stored contents of the field “non-suppression target terminal list” of the record whose peripheral terminal address in the field “peripheral terminal address” of the terminal list management table matches the MAC address of the communication partner station. Update to the non-suppression target terminal list input from the target identification unit 15a (step S93
- the suppression target identification unit 15a creates a suppression target terminal list of the communication partner station, and outputs it to the terminal list storage unit 25.
- Terminal list storage unit 25 manages terminal list Suppression target terminal list input from the suppression target identification unit 15a with the stored contents of the field "Suppression target terminal list" of the record in which the peripheral terminal address of the field "Peripheral terminal address" matches the MAC address of the communication partner station (Step S94).
- the MAC control unit 18a refers to the terminal list management table in the terminal list storage unit 25 and records the field "Peripheral" in the record in which the peripheral terminal address in the field "Peripheral terminal address" matches the MAC address of the own station. Read the first peripheral terminal list from the "terminal list”. And
- the MAC control unit 18a creates an RTI response frame storing the first peripheral terminal list, and the created RTI response frame is transmitted as a high-frequency signal via the RF unit 20, the switch circuit 12, and the antenna 11-1. (Step S95).
- the receiving station 3b transmits an RTI request frame fl including the contents of the first peripheral terminal list to the transmitting station 3a.
- the transmitting station 3a transmits an RTI response frame f2 including the contents of the second peripheral terminal list to the receiving station 3b.
- the processing from step S81 to step S88 is executed in the receiving station 3b.
- the transmitting station 3a transmits an RTI request frame f3 including the contents of the second peripheral terminal list to the receiving station 3b.
- the receiving station 3b transmits an RTI response frame f4 including the contents of the first peripheral terminal list to the transmitting station 3a.
- the processing from step S81 and step S89 to step S95 is executed in the receiving station 3b.
- FIG. 18 is a diagram illustrating an example of reception processing at the time of measuring the feature amount performed by the wireless station 3b in FIG.
- the wireless station (transmitting station) 3a and the wireless station (receiving station) 3b are performing wireless communication
- the wireless station (interfering station) 3d and the wireless station (interfering station) 4a are performing wireless communication.
- the MAC addresses of the wireless stations 3a, 3b, 3d, and 4a are “3a”, “3b”, “3d”, and “4a,” respectively. Force located within Radio station 4a Les, not within the range. Radio station 3b is located within the radio wave coverage of radio station 3d and radio station 4a.
- the interfering station 3d transmits a data frame fl 1 having a transmission source address “3d” and a destination address “4a”. Since the transmitting station 3a and the receiving station 3b are located within the radio wave coverage of the interference station 3d, the transmitting station 3a and the receiving station 3b receive the data frame f11 and based on the source address of the data frame f11. The contents stored in the terminal list storage unit 25 are updated, and the feature quantity of the interference signal is measured based on the data frame fl 1.
- the interfering station 4a transmits an ACK frame f12 whose destination address is “3d”. Since the receiving station 3b has a force S located within the radio wave arrival range of the interference station 4a, and the transmitting station 3a is not located within the radio wave arrival range of the interference station 4a, only the receiving station 3b receives the ACK frame f12.
- the interfering station 4a transmits an RTS (Request to Send) frame f15 having a source address “3d” and a destination address “4a”. Since the receiving station 3b is located within the radio wave coverage of the interference station 4a and the transmitting station 3a is not located within the radio wave reach of the interference station 4a, only the receiving station 3b receives the RTS frame f15 and receives the RTS frame f.
- the content of the terminal list storage unit 25 is updated based on the 15 transmission source addresses, and the feature quantity of the interference signal is measured based on the RTS frame f15.
- the interfering station 3d transmits a CTS (Clear To Send) frame f 16 whose destination address is “4a”. Since the transmitting station 3a and the receiving station 3b are located within the radio wave reach of the interference station 3d, the transmitting station 3a and the receiving station 3b receive the data frame f11 and receive the NAV (Network Transmission is prohibited for a period based on (Allocation Vector) information.
- CTS Car To Send
- NAV Network Transmission is prohibited for a period based on (Allocation Vector) information.
- the interfering station 4a transmits data frames fl 7 and fl 8 having a transmission source address “4a” and a destination address “3d”. Then, the interference station 4a transmits a BAR (Block ACK Request) frame f19 having a transmission source address “4a” and a destination address “3d”.
- the receiving station 3b is positioned within the radio wave reach of the interfering station 4a. Since the transmitting station 3a is not located within the radio wave reaching range of the interfering station 4a, only the receiving station 3b is the data frame fl 7, fl 8 and BAR frame. Receives fl 9, updates the contents stored in the terminal list storage unit 25, and measures the feature quantity of the received signal. [0140]
- the interference station 3d transmits a BA (Block ACK) frame f20 having a destination address "4a" as reception confirmation of the BAR frame f19. This is received by both the transmitting station 3a and the receiving station 3b.
- FIG. 19 is a diagram illustrating an example of reception processing performed when the radio station 3b in FIG. 10 suppresses interference.
- the wireless station (transmitting station) 3a and the wireless station (receiving station) 3b are performing wireless communication.
- the MAC addresses of radio stations 3a and 3b are “3a” and “3b”, respectively.
- the transmitting station 3a transmits a data frame f21 having a source address power S "3a" and a destination address "3b", and the receiving station 3b receives the data frame f21. Since the destination address “3b” is its own MAC address, the receiving station 3b switches the operation mode from the “interference measurement mode” to the “interference suppression mode” and suppresses the interference signal component from the data frame f21. Process. Then, when the arrival of the data frame 21 is completed, the receiving station 3b switches the operation mode from the “interference suppression mode” to the “interference measurement mode”.
- the receiving station 3b transmits the ACK frame f22 with the destination address "3a", and the transmitting station 3a receives the ACK frame f22. Since the destination address “3a” is the MAC address of the local station, the transmitting station 3a switches the operation mode from the “interference measurement mode” to the “interference suppression mode” and performs processing to suppress the interference signal component from the ACK frame f22. . Then, when the arrival of the ACK frame 21 is completed, the receiving station transmitting station 3a switches the operation mode from the “interference suppression mode” to the “interference measurement mode”.
- the present invention is not limited to the above-described embodiment.
- the present invention may be as follows.
- the feature amount of the signal used for interference suppression has been described as only one, but the present invention is not limited to this.
- the number of signal features used for interference suppression is increased, the ability to suppress interference signals more effectively from the received signal will increase, the number of antennas will increase, and signal feature measurement and interference signal suppression will increase.
- the processing circuit for this will become large, leading to an increase in cost. For this reason, it is desirable to determine the number of feature quantities of a signal used for interference suppression based on the interference signal suppression capability and cost.
- the method of selecting the signal feature value used for interference suppression from the signal feature values related to the transmission source to be suppressed is the signal feature value for which the latest signal feature measurement was performed. You can choose anything.
- a function may be added to the first embodiment described above, in which a transmission source that transmits a signal that has arrived within the interference measurement prohibition period is not a signal source to be suppressed.
- the interference measurement prohibition period is a period during which a desired signal may be received from the radio station of the communication partner.
- the arrival timing of the signal falls within the interference measurement prohibited period between NO in step S37 ("preamble detected?") And step S33 ("determined as a signal source to be suppressed").
- a step of determining whether or not it is included is provided. If the arrival timing of the signal is within the interference measurement prohibition period, it is determined that the signal is not subject to suppression, and the measured feature quantity of the signal being received is not stored. On the other hand, if the arrival timing of the signal is not within the interference measurement prohibited period, the process proceeds to step S33. As a result, it is possible to avoid suppressing the interference signal from the received signal using the feature quantity of the desired signal received during the interference measurement prohibition period.
- the receiving station transmits a QoS CF-Poll frame to the transmitting station.
- the QoS CF—Poll frame transmitted by the receiving station includes the MAC address of the transmitting station to which the receiving station grants the transmission right and the period during which the transmitting station that has given the transmission right can transmit the radio packet signal (hereinafter referred to as transmission permission). This is called the period.)
- the transmitting station that has received the QoS CF_Poll frame from the receiving station recognizes that the transmission right has been granted from the contents of the QoS CF_Poll frame, and the time when SIFS has elapsed since the reception of the QoS CF_Poll frame was completed.
- the transmission of the data frame is started at the latest, and the transmission of the data frame is terminated at the time Tb when the transmission permission period has elapsed from the time Ta at the latest.
- the receiving station that has received the data frame completes reception of the data frame and then performs SIFS. After the elapse of time, an ACK frame is sent to the transmitting station to notify the data frame reception confirmation.
- the receiving station when transmitting the QoS CF-Poll frame, sets the period from time Ta to time Tb as the interference measurement prohibited period.
- the receiving station transmits a data frame to the transmitting station.
- the transmitting station receives the data frame, starts transmission of the ACK frame to notify the receipt of the data frame at time TA when SIFS has elapsed since the end of data frame reception, and transmits the ACK frame at time TB. Exit.
- the receiving station when it transmits a data frame, it sets the period from time TA to time TB as the interference measurement prohibited period.
- the power receiving station in order for the receiving station to obtain the second peripheral terminal list from the transmitting station, the power receiving station has previously transmitted the RTI request frame in a predetermined time unit. Radio station power that did not receive the signal
- the timing to transmit the RTI request frame is limited, such as the timing to receive the RTI request frame and the timing when the reception error rate exceeds a certain value. It is not a thing.
- the RTI request frame and the RTI response frame are transmitted between the transmitting station and the receiving station.
- the RTI request frame and the RTI response frame are transmitted between the transmitting station and the receiving station.
- it is not limited to this.
- the receiving station 3b has a destination address of MA of the transmitting station 3a.
- Send CTS (Clear to Send) frames f31 and f32 indicating the C address twice in succession.
- the transmitting station 3a receives CTS frames f31 and f32 whose destination address matches the MAC address of its own station twice, it transmits the RTI response frame f 33 containing the contents of the second peripheral terminal list. May be.
- the transmission station 3a transmits the RTI response frame f33 that does not indicate the destination address.
- Receiving station 3b is the RTI response frame addressed to the local station if the RTI response frame f 33 is received before the preset time elapses after the second CTS frame f 32 is transmitted. Judge that.
- the radio station (receiving station) 3b does not store information such as the peripheral terminal list in the terminal list management table shown in FIG.
- Information such as a peripheral terminal list may be stored in a terminal list management table as an example.
- the field “recognizable terminal address” stores the MAC address of the own station and the MAC address of the recognizable terminal one by one.
- the MAC address of the recognizable terminal stored in the field “recognizable terminal address” is the source address and destination address of the MAC header of the signal received by the local station, that is, the radio that transmitted the signal. It is the MAC address of the station (transmitting station) and the MAC address of the wireless station (receiving station).
- the field "recognizable terminal list” stores the source address and destination address of the MAC header of each signal previously received by the radio station having the corresponding recognizable terminal address.
- peripheral terminal list stores the source address of the MAC header of each signal previously received by the wireless station having the corresponding peripheral terminal address.
- the MAC address of the hidden terminal is stored in the field “hidden terminal list”. If the wireless station with the corresponding recognizable terminal address sniffs the exchange of signals between neighboring wireless stations, receives only the response request signal, and fails to receive the response signal for the response request signal, the response request signal
- the destination address is the MAC address of the hidden terminal.
- An AC address may be stored.
- the receiving station 3b transmits the peripheral terminal list of the transmitting station 3a according to the procedure shown in FIG. And a hidden terminal list can be acquired.
- the interfering station 3d is a peripheral terminal of the transmitting station 3a
- the interfering station 4a is a hidden terminal of the transmitting station 3a.
- the MAC addresses of the transmitting station 3a, the receiving station 3b, the interfering station 3d, and the interfering station 4a are “3a”, “3b”, “3d”, and “4a”, respectively.
- the receiving station 3b transmits the CTS frames f41 and f42 whose destination address is “3a” twice in succession.
- transmitting station 3a receives CTS frames f41 and f42 with the destination address "3a" twice in succession, it reads the peripheral terminal list of its own station from the terminal list management table in Fig. 21 stored in its own station. . It is assumed that “3d” is included in the read peripheral terminal list.
- the transmitting station 3a has the source address "3a" and the destination address is included in the peripheral terminal list "
- RTS frame f43 that is 3d " is transmitted.
- the receiving station 3b transmits the destination address of the RTS frame f43 received from the transmission of the second CTS frame f42 until the preset time elapses.
- Receiving station 3b transmits CTS frames f44 and f45 whose destination address is "3a" twice in succession.
- the transmitting station 3a receives CTS frames f44 and f45 with the destination address "3a" twice in succession, the transmitting station 3a obtains its own hidden terminal list from the terminal list management table in FIG. read out. It is assumed that “4a” is included in the read hidden terminal list.
- the transmitting station 3a transmits an empty data frame f46 having a transmission source address "3a" and a destination address "4a" included in the hidden terminal list.
- the receiving station 3b transmits the destination address of the data frame f46 received from the transmission of the second CTS frame f45 until the preset time has elapsed, from the hidden terminal of the transmitting station 3a. Judged as a MAC address.
- the receiving station 3b obtains all the contents of the peripheral terminal list and the hidden terminal list of the transmitting station 3a from the transmitting station 3a by repeatedly transmitting two CTS frames in succession. can do.
- the wireless station (receiving station) 3b receives a signal transmitted / received between wireless stations performing wireless communication regardless of its own station, and converts the received signal into the received signal. Based on this, the feature amount of the signal is acquired.
- the present invention is not limited to this.
- the receiving station 3b measures the feature amount of the signal from the radio station listed in the suppression target terminal list related to the transmitting station 3a.
- the receiving station 3b obtains the second peripheral terminal list from the transmitting station 3a by the exchange procedure shown in FIG. 17, and creates a suppression terminal target list based on the first peripheral terminal list and the second peripheral terminal list.
- the suppression target terminal list it is assumed that the MAC addresses of the interference station 4a and the interference station 4b are listed.
- the MAC addresses of the transmitting station 3a, the receiving station 3b, the interference station 4a, and the interference station 4b are “3a”, “3b”, “4a”, and “4b”, respectively.
- the receiving station 3b transmits an RTS frame f51 whose transmission source address is “3b” and whose destination address is “4a” listed in the suppression target terminal list.
- the interfering station 4a receives the RTS frame f51 having the destination address “4a”
- the interfering station 4a transmits the CTS frame having the destination address “3b”.
- the receiving station 3b measures the signal feature amount based on the CTS frame f52. As a result, the receiving station 3b acquires the feature quantity of the signal transmitted from the interference station 4a.
- the receiving station 3b transmits the data frame f53 having the transmission source address "3b" and the destination address "4b" listed in the suppression target terminal list.
- the interfering station 4b receives the data frame f53 having the destination address “4b”
- the interfering station 4b transmits the ACK frame f54 having the destination address “3b”.
- the receiving station 3b measures the feature amount of the signal based on the ACK frame f54. As a result, the receiving station 3b acquires the feature quantity of the signal transmitted from the interference station 4b.
- a wireless LAN system using CSMA Carrier Sense Multiple Access
- TDMA Time Division Multiple Access
- FD MA Frequency Division Multiple Access
- CDMA Code It can be applied to wireless communication systems that use various access methods such as Division Multiple Access (SDMA) and Space Division Multiple Access (SDMA).
- SDMA Division Multiple Access
- SDMA Space Division Multiple Access
- each of the above embodiments is typically an LSI (Large Scale) that is an integrated circuit.
- IC Integrated Circuit
- system LSI super LSI
- ultra LSI ultra LSI
- the method of circuit integration is not limited to LSI's, and implementation using dedicated circuitry or general purpose processors is also possible.
- An FPGA Field Programmable Gate Array
- a reconfigurable 'processor that can reconfigure the connection and settings of circuit cells inside the LSI may be used.
- the present invention can be used particularly for a receiving station that suppresses an interference signal superimposed on a desired signal in a wireless communication system in which a wireless packet signal is transmitted randomly as in the CSMA scheme. .
Description
Claims
Priority Applications (5)
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JP2008514515A JP5175718B2 (ja) | 2006-05-09 | 2007-05-09 | 干渉抑圧方法及び干渉抑圧装置 |
EP16190119.4A EP3131236B1 (en) | 2006-05-09 | 2007-05-09 | Interference suppression method and interference suppression device |
EP07743042.9A EP2020779B1 (en) | 2006-05-09 | 2007-05-09 | Interference suppression method and interference suppression device |
US12/299,933 US8311165B2 (en) | 2006-05-09 | 2007-05-09 | Interference suppression method and interference suppression device |
CN2007800167120A CN101438536B (zh) | 2006-05-09 | 2007-05-09 | 干扰抑制方法和干扰抑制装置 |
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WO (1) | WO2007129737A1 (ja) |
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US8868140B2 (en) | 2008-12-08 | 2014-10-21 | Samsung Electronics Co., Ltd. | Method and system for integrated wireless power and data communication |
US9064404B2 (en) | 2008-12-08 | 2015-06-23 | Samsung Electronics Co., Ltd. | Method and system of radio frequency (RF) power transmission in a wireless network |
JP2013518478A (ja) * | 2010-01-26 | 2013-05-20 | エントロピック・コミュニケーションズ・インコーポレイテッド | 通信ネットワークにおいてサイレントシンボルを使用する方法及び装置 |
KR102367242B1 (ko) * | 2020-09-11 | 2022-02-23 | 주식회사 에스원 | 송수신 일체형 광학 센서의 신호 간섭 방지 방법 및 장치 |
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CN101438536A (zh) | 2009-05-20 |
CN101438536B (zh) | 2012-01-04 |
US8311165B2 (en) | 2012-11-13 |
US20090147893A1 (en) | 2009-06-11 |
EP2020779B1 (en) | 2016-11-09 |
JP5175718B2 (ja) | 2013-04-03 |
JPWO2007129737A1 (ja) | 2009-09-17 |
EP2020779A1 (en) | 2009-02-04 |
EP2020779A4 (en) | 2015-09-23 |
EP3131236A1 (en) | 2017-02-15 |
EP3131236B1 (en) | 2020-05-06 |
US20130034195A1 (en) | 2013-02-07 |
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