JP2010074460A - Wireless communication system, communication apparatus, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption in a communication apparatus by controlling a demodulating operation. <P>SOLUTION: In the communication apparatus 100 for performing secondary modulation by OFDM, the pattern of a synchronizing signal associated with a reception side address is set in a sub-carrier modulating part 320 at transmission by a control part 110. In the communication apparatus 100 which receives a modulation signal with such a synchronizing signal added thereto, a synchronizing signal pattern associated with a self address is set in a synchronization processing part 420, which performs synchronization establishment using the synchronizing signal, by the control part 110. The synchronization processing part 420 uses a matched filter, where the coefficient of the synchronizing signal pattern is set in a register, so as to detect a symbol timing only in receiving the modulating signal which becomes the set synchronizing signal pattern, and to perform respective kinds of processing concerning demodulation. Consequently, when a packet not addressed to a self terminal is received, an operation related to the demodulation is not performed, thereby reducing the power consumption. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless communication system, a communication device, and a program, and more particularly, to a wireless communication system, a communication device, and a program suitable for reducing power consumption.

  An OFDM (Orthogonal Frequency Division Multiplexing) method is adopted as a secondary modulation method used for wireless communication such as a wireless LAN (Local Area Network) (for example, IEEE802.11a). .

  In packet communication using OFDM, a short training symbol carrying a known signal on a specific subcarrier and a long training symbol carrying a known signal on all subcarriers are transmitted as synchronization signals (preamble signals). On the receiving side, symbol timing synchronization and carrier synchronization are performed based on such a synchronization signal. After such a synchronization operation, it is determined whether the packet is addressed to itself based on the address information recorded in the data portion (for example, Patent Document 1).

JP 2003-224537 A

  In such conventional OFDM communication, every time a packet is transmitted, all terminals need to perform symbol timing synchronization, carrier synchronization, and address reception. That is, even when a packet destined for a destination other than the own terminal is transmitted, the address reception after the synchronization operation is performed.

  Here, the synchronization operation can be performed based on a synchronization signal added as a preamble signal of a packet. However, reception of an address performed after synchronization is accompanied by a demodulation operation of a data portion following the preamble signal. Therefore, for a terminal that is not the destination of the transmitted packet, a demodulation operation is performed in order to obtain address information other than itself. Therefore, if control for limiting such demodulation operation can be performed, power consumption can be further reduced.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a wireless communication system, a communication apparatus, and a program capable of reducing power consumption.

In order to achieve the above object, a wireless communication system according to a first aspect of the present invention includes:
In a wireless communication system including a plurality of communication devices that perform wireless communication by performing reception synchronization with a synchronization signal added by secondary modulation,
The source communication device is
Transmits a modulation signal in which a synchronization signal that is a pattern associated with identification information assigned to a destination communication device is set,
The destination communication device is:
When the received synchronization signal pattern of the modulated signal corresponds to the identification information assigned to the destination communication device, the operation for demodulation of the modulated signal is performed.
It is characterized by that.

In order to achieve the above object, a communication apparatus according to the second aspect of the present invention provides:
In a communication apparatus that performs radio communication by performing reception synchronization with a synchronization signal added by secondary modulation,
Receiving means for receiving a modulated signal transmitted by wireless communication;
Discrimination for determining whether or not the pattern of the synchronization signal included in the modulated signal received by the receiving means matches the pattern of the synchronization signal associated with the identification information assigned to the communication device Means,
A demodulating means for performing an operation related to demodulation of the modulated signal received by the receiving means when the discriminating means determines that the patterns of the synchronization signals match;
It is characterized by providing.

In the communication device,
The discriminating means is preferably composed of a matched filter including one or more registers whose coefficients are synchronization signals corresponding to identification information assigned to the communication device.

The communication device is
It is desirable to further include coefficient setting means for setting a coefficient in the matched filter register based on the identification information assigned to the communication device.

In the communication device,
The synchronization signal may be a training symbol added by secondary modulation using an orthogonal frequency division multiplexing method,
Preferably, the coefficient setting means sets a coefficient indicating a phase pattern of a short training symbol and a long training symbol, which is associated with the identification information.

The communication device is
It is desirable to further include transmission means for transmitting a modulated signal including a plurality of subcarriers.
It is desirable that the transmission means adds a synchronization signal having a pattern corresponding to identification information assigned to a transmission destination device to each subcarrier for transmission.

In order to achieve the above object, a program according to the third aspect of the present invention is:
To a computer that controls a communication device that performs radio communication by performing reception synchronization with a synchronization signal added by secondary modulation,
A function for setting a coefficient based on identification information assigned to the communication device in a matched filter register for detecting a received synchronization signal;
It is characterized by realizing.

The above program
In the computer,
A function of adding a synchronization signal of a pattern corresponding to identification information assigned to a transmission destination device to each subcarrier to a modulation signal to be transmitted;
It is desirable to realize further.

  According to the present invention, the power consumption of the communication device can be reduced.

  Embodiments according to the present invention will be described below with reference to the drawings. In the present embodiment, a case where the communication system according to the present invention is realized by a wireless LAN system will be described as an example.

  A wireless LAN system 1 according to the present embodiment in this case will be described with reference to FIG. FIG. 1 is a diagram schematically showing a configuration of a wireless LAN system 1 according to the present embodiment. Note that the wireless LAN system 1 according to the present embodiment uses a multicarrier transmission method such as an OFDM (Orthogonal Frequency Division Multiplexing) method for secondary modulation such as IEEE802.11a, for example. Assume that it is a LAN system.

  A frame configuration of data transmitted and received in this case will be described with reference to FIG. As shown in the figure, data transmitted by the OFDM method usually starts with a “preamble” as a synchronization signal used for reception synchronization, and includes “SIGNAL” including physical layer header information and “data” of actual data. The following frame configuration.

  The OFDM system is sometimes used in broadcasting such as digital broadcasting. In such a case, “continuous mode” in which the time required for establishing synchronization is allowed to some extent is used. Since the receiving side does not know when the next packet will arrive, the “packet mode” for establishing synchronization in a short time is adopted. In this packet mode, synchronization in a short time is realized by a preamble synchronization signal added to the head of a frame.

  As shown in FIG. 2, this synchronization signal (preamble) includes a “short training symbol” composed of 10 symbols (t1 to t10), a guard interval (GI), and two symbols (T1, T2). It is comprised by the "long training symbol" comprised from. Since the signal length of each symbol of the short training symbol is 0.8 μs, the signal length of the short training symbol is 8 μs. In addition, since the signal length of GI in the long training symbol is 1.6 μs and the signal length of each of the two symbols is 3.2 μs, the signal length of the long training symbol is also 8 μs. Therefore, the signal length of the preamble (synchronization signal) is 16 μs. By representing a known fixed pattern with such short training symbols and long training symbols, reception synchronization in a short time is realized.

  Here, the OFDM scheme is a multicarrier transmission scheme in which data signals are distributed over a plurality of subcarriers (frequencies) and multiplexed and transmitted in parallel. In a wireless LAN using the OFDM system, 52 subcarriers are usually multiplexed. In this case, in the preamble, for example, a short training symbol and a long training symbol are set so as to have a fixed pattern as shown in FIG. In other words, when 52 subcarriers (frequency) are multiplexed, subcarriers distributed at a frequency of ± 26 are multiplexed, and among these, short training symbols are set to 12 subcarriers. In addition, by setting long training symbols for all 52 subcarriers, a known fixed pattern is represented.

  The wireless LAN system 1 according to the present embodiment performs communication by transmitting and receiving a modulated signal (radio wave) secondarily modulated by the OFDM method having such a data structure. As shown in FIG. 1, the communication apparatus 100 includes two or more communication devices 100 that perform wireless communication.

  In this case, the two or more communication devices 100 constituting the wireless LAN system 1 can take various forms. That is, the communication device 100 is, for example, a wireless LAN access point (AP), a terminal device with a built-in wireless LAN client function (for example, a mobile phone or a smartphone, a PDA (Personal Digital Assistants: personal digital assistant), a personal computer, etc.) The present invention can be embodied as a wireless LAN card (wireless LAN module), and other various devices using a wireless LAN function (for example, a digital camera, a game machine, a wireless communication device for industrial use, etc.).

  Among these, the communication device 100 that functions as a wireless LAN access point (AP) is configured to perform wireless communication with other communication devices 100, and for communicating via a trunk line NW such as a wired LAN. It shall have a configuration.

  In the wireless LAN system 1 according to the present embodiment, at least one of the two or more communication devices 100 functions as a wireless LAN access point (AP), and the other communication devices 100 have a wireless LAN access point (AP). It is assumed that wireless communication is performed with the communication device 100 functioning as (). It is assumed that the wireless LAN system 1 according to the present embodiment conforms to IEEE802.11a, which employs OFDM for secondary modulation, and performs communication in the OFDM packet mode.

  Thus, although the form of the communication apparatus 100 concerning this embodiment is not restricted to one, it is the same about the fundamental structure and function concerning wireless communication. The configuration of such a communication device 100 will be described with reference to FIG. FIG. 4 is a block diagram schematically showing a configuration related to wireless communication in the communication apparatus 100 according to the embodiment of the present invention.

  As illustrated, the communication apparatus 100 includes a control unit 110, a storage unit 120, a wireless communication unit 200, and the like.

  The control unit 110 includes, for example, an arithmetic device such as a CPU (Central Processing Unit) and performs various processes by executing a program stored in the storage unit 120, and the communication device 100. Control each part.

  The storage unit 120 is configured by, for example, a non-volatile semiconductor storage device such as a flash memory, and stores a program executed by the control unit 110 and stores data necessary for processing, processing result data, and the like. .

  The wireless communication unit 200 is configured to perform a wireless communication operation in the communication device 100. The configuration of the wireless communication unit 200 according to the present embodiment will be described with reference to FIG. FIG. 5 is a block diagram illustrating a configuration of the wireless communication unit 200.

  As described above, the communication device 1 according to the present embodiment is a wireless LAN access point (AP) or a wireless LAN client, and performs transmission / reception by wireless communication. Therefore, as shown in FIG. 5, the wireless communication unit 200 includes a transmission unit 300 and a reception unit 400, and the transmission unit 300 and the reception unit 400 share the antenna 210 that is used for both transmission and reception. The antenna switch 220 is included.

  As illustrated in FIG. 5, the transmission unit 300 includes a serial-parallel conversion unit 310, a subcarrier modulation unit 320, an IFFT unit 330, a parallel-serial conversion unit 340, an RF unit 350, and the like.

  The serial-to-parallel converter 310 multiplexes in parallel using the OFDM method, so that parallel data obtained by dividing the data string of the transmission target data into the number of subcarriers (for example, 52) by rearranging bits by interleaving processing. Convert to

  The subcarrier modulation unit 320 includes a modulation circuit for the number of subcarriers, and performs modulation (primary modulation) for each divided subcarrier. At this time, frame processing of each subcarrier is performed, and a preamble serving as a synchronization signal is added. In the present embodiment, such synchronization signal addition is performed under the control of the control unit 110, so that the synchronization signal pattern, which has conventionally only been a known fixed pattern, is identified to identify the communication device to be received. A pattern according to information (for example, address) is used.

  The IFFT unit 330 is a circuit that performs Inverse Fast Fourier Transform (IFFT), and performs inverse fast Fourier transform on the subcarriers modulated by the subcarrier modulation unit 320, thereby converting a plurality of subcarrier modulation signals. A synthesized multicarrier signal is generated.

  The parallel-serial conversion unit 340 inserts a guard interval into the multicarrier signal generated by the IFFT unit 330 and performs symbol shaping and the like, and then converts the signal into an analog signal by a DAC (Digital-Analog Converter). Convert.

  The RF unit 350 converts the converted analog signal into a high-frequency radio signal (RF signal (RF: Radio Frequency)). The RF unit 350, for example, converts the signal to an intermediate frequency radio signal using an intermediate frequency oscillator or a quadrature modulation circuit, and then converts the signal to a radio frequency (RF) signal using a radio frequency oscillator or an HPA (High Power Amplifier). The data is converted and transmitted from the antenna 210.

  With such a configuration, when the communication apparatus 100 becomes the transmission side, the transmission target data is secondarily modulated by the OFDM method and transmitted.

  Next, the configuration of the receiving unit 400 will be described. As illustrated in FIG. 5, the reception unit 400 includes an RF unit 410, a synchronization processing unit 420, a parallel / serial conversion unit 430, an FFT unit 440, a demodulation unit 450, and the like.

  The RF unit 410 processes a high-frequency radio signal (RF signal (RF: Radio Frequency)) transmitted from another communication apparatus 100 and received by the antenna 210. For example, the RF unit 410 is a low noise amplifier (LNA). ) And the like, a radio frequency oscillator, an AGC (Automatic Gain Control), and the like, and corrects the reception level of the received RF signal.

  The synchronization processing unit 420 performs a reception synchronization operation based on the synchronization signal in the input modulation signal. In this embodiment, as a synchronization signal of the transmitted OFDM signal, a synchronization signal having a pattern corresponding to identification information (for example, an address) that identifies a receiving device is added. During the synchronization operation, whether the packet is addressed to itself is distinguished based on the synchronization signal. The configuration of the synchronization processing unit 420 that performs such operations will be described with reference to FIG.

  FIG. 6 is a block diagram illustrating a configuration of the synchronization processing unit 420 according to the present embodiment. As illustrated, the synchronization processing unit 420 includes a quadrature detection unit 421, a local oscillator 422, an ADC 423, an AFC 424, a timing detection unit 500, and the like.

  The quadrature detection unit 421 converts the input RF signal into an intermediate frequency radio signal based on the oscillation signal from the local oscillator 422 that is an intermediate frequency oscillator, and outputs the radio signal to the ADC 423.

  The ADC 423 is an analog-digital converter (ADC), which converts an input intermediate frequency signal into digital data and outputs the digital data to the AFC 424 and the timing detection unit 500.

  The AFC 424 is a circuit that performs automatic frequency control (AFC). Based on the timing detection operation in the timing detection unit 500, the AFC 424 corrects a difference between radio frequencies on the transmission side and the reception side (carrier frequency synchronization). ). The AFC 424 obtains the carrier frequency error by detecting the average phase rotation amount based on the correlation between the repeated signal sections in the preamble, and performs carrier frequency synchronization.

  Timing detection section 500 performs symbol timing synchronization for detecting the timing of an OFDM symbol from a preamble synchronization signal converted into digital data. In the present embodiment, at the time of symbol timing synchronization by the timing detection unit 500, discrimination is made as to whether the destination of the received packet is addressed to itself based on the pattern of the synchronization signal. A timing detection unit 500 according to the present embodiment that performs such an operation will be described with reference to FIG.

  First, the configuration of the timing detection unit 500 will be described with reference to FIG. FIG. 7A is a block diagram illustrating a configuration of the timing detection unit 500 according to the present embodiment. As shown in the figure, the timing detection unit 500 according to the present embodiment includes a matched filter 510, a symbol timing detection unit 520, and the like.

  The matched filter 510 detects the peak signal in the repetitive signal section of the preamble signal by using each sample value on the time axis of the input OFDM signal as a tap coefficient and outputting a peak value. In the case of OFDM, as described above, a preamble is composed of a short training symbol and a long training symbol, and the short training symbol is a repetitive signal section. Therefore, timing detection is performed using the fact that the correlation peak signal repeatedly detected when the short training symbol is received disappears when the long training symbol is received. In other words, when the preamble is input to the matched filter, a signal in which the peak portion between each symbol of the short training symbol becomes apparent as shown in FIG. 7B is output.

Such timing detection using a matched filter is conventionally performed. A configuration of a conventional matched filter is shown in FIG. In a general matched filter, received OFDM signals (R _{0 to} R _N-1 ) are used as registers, and tap coefficients (M _{0 to} M _N ) storing OFDM signals that are not affected by multipath or noise. _-1 ) is multiplied for each sample, and the multiplication results are added and output. Since the OFDM signal has no correlation with each sample in the time axis direction, a sharp peak value is output only when each sample value of the received OFDM signal matches the signal held in each tap coefficient.

  Since a normal OFDM signal has a known fixed pattern based on a short training symbol and a long training symbol, a peak value necessary for timing synchronization can be detected by storing a known value in a tap coefficient. .

  In this embodiment, by changing the phase of the short training symbol and the long training symbol, which are fixed patterns, according to the address on the receiving side, it is possible to distinguish whether the packet is addressed to itself at the stage of synchronization processing on the receiving side. Like that. In order to realize such an operation, in this embodiment, a matched filter 510 having a configuration as shown in FIG. 8B is used.

  That is, in the conventional matched filter, as shown in FIG. 8A, only the received signal is used as a register. However, in the matched filter 510 according to the present embodiment, as shown in FIG. Not only the signal register 511 but also the tap coefficient register 512 is prepared so that timing detection can be performed with a variable tap coefficient. In this case, a tap coefficient is set in the register 512 by the control unit 110.

  In this case, by setting the received signal corresponding to the address assigned to the communication device 100 as a tap coefficient, the matched filter 510 outputs a peak signal only when a synchronization signal having a pattern corresponding to the address is input. The included synchronization signal is output to the symbol timing detection unit 520.

  The symbol timing detection unit 520 detects symbol timing based on the peak position indicated by the output from the matched filter 510. As described above, in OFDM, a peak value appears when a short symbol is received, but a signal design is made so that no peak value appears when a long training symbol is received. Therefore, the peak signal in the output signal of the matched filter 510 is By detecting that it does not appear, it is possible to detect the timing of the short training symbol and the long training symbol.

  Here, as described above, the matched filter 510 according to the present embodiment outputs a signal in which a peak signal is manifested only when a synchronization signal having a pattern corresponding to its own address is input. Therefore, symbol timing detection is performed only when the synchronization signal for the self-addressed packet is processed. That is, when a packet that is not addressed to itself is received, symbol timing is not detected at the stage of the synchronization process, so that no received signal is sent out after the synchronization process.

  In other words, by setting the tap coefficient indicating the synchronization signal pattern corresponding to the address assigned to itself to the matched filter 510, it is possible to distinguish whether the packet is addressed to itself at the stage of the synchronization signal processing during reception synchronization. Will be. Here, when a packet addressed to itself is received, the symbol timing detection unit 520 detects the symbol timing, and the received signal is output to the subsequent parallel-serial conversion unit 430.

  In this case, the configuration after the parallel-serial converter 430 that processes the received signal will be described with reference to FIG.

  The parallel / serial conversion unit 430 uses the symbol timing detected by the symbol timing detection unit 520 to remove the guard interval from the received OFDM signal.

  The FFT unit 440 demultiplexes the OFDM signal in which a plurality of subcarriers are multiplexed into a subcarrier by performing a fast Fourier transform (FFT) on the OFDM signal from which the guard interval is removed.

  Demodulation section 450 demodulates the modulated signal (primary modulation) for each subcarrier that has been demultiplexed. Before and after the demodulation operation, channel equalization, deinterleaving processing, Viterbi decoding, and the like are performed and output to the control unit 110 as decoded data.

  As described above, in the communication apparatus 100 according to the present embodiment, when a preamble is added at the time of transmission, a synchronization signal having a pattern corresponding to an address to be received is set, and a modulation signal to which such a synchronization signal is added is received. The communication apparatus 100 performs a process subsequent to the synchronization process only when receiving an OFDM signal in which a packet addressed to itself is multiplexed. That is, when a packet other than one addressed to itself is received, each process related to demodulation such as guard interval removal, demultiplexing into subcarriers by Fourier transform, and demodulation operation is not performed. Reduction can be achieved.

  Such an operation is realized by the control unit 110 controlling the operation of the wireless communication unit 200. In this case, functions realized by the control unit 110 will be described with reference to FIG. FIG. 9 is a functional block diagram illustrating functions realized when the control unit 110 executes a program stored in the storage unit 120.

  As illustrated, the control unit 110 functions as a pattern acquisition unit 111, a synchronization signal setting unit 112, a coefficient setting unit 113, and the like.

  The pattern acquisition unit 111 transmits the OFDM signal designating the address on the receiving side at the time of transmission, and the address necessary for reducing power consumption by distinguishing whether the packet is addressed to itself at the time of reception. Information indicating a correspondence relationship with the synchronization signal pattern is acquired from the storage unit 120.

  In the case of a wireless LAN system as exemplified in the present embodiment, the wireless LAN system includes a communication device 100 (AP) that functions as an access point and a communication device 100 that communicates with the communication device 100 (AP) (see FIG. 1). In a wireless communication system in which a communication partner is specified, each communication device 100 can perform the above-described operation by sharing in advance information that associates an address with a synchronization signal pattern.

  In this case, a correspondence table as shown in FIG. 10 is stored in the storage unit 120 of each communication device 100 configuring the wireless LAN system 1. As shown in FIG. 10, this correspondence table is a table in which combinations of subcarriers in which a short training symbol is set as a phase for a long training symbol are associated with each address assigned to the communication apparatus 100. That is, the phases of the short training symbol and the long training symbol, which are conventionally known fixed patterns, are expanded to a plurality of patterns corresponding to a plurality of addresses and associated with the addresses.

  In the correspondence table illustrated in FIG. 10, in an OFDM signal using 52 subcarriers, eight different addresses are displayed depending on which of 12 subcarriers used for 12 subcarriers used for a short training symbol. Shows the case. The address associated with the synchronization signal pattern does not need to be uniquely assigned to each communication device 100, and may be an address indicating a group constituted by a plurality of communication devices 100.

  When the communication apparatus 100 is on the transmission side, the pattern acquisition unit 111 receives a synchronization signal pattern (a combination of subcarriers in which a short training symbol is set) corresponding to an address assigned to the communication apparatus 100 to be received. ) From the storage unit 120 and when the communication apparatus 100 is a receiving side, a synchronization signal pattern (a combination of subcarriers in which a short training symbol is set) corresponding to an address assigned to the communication apparatus 100 ) Is acquired from the storage unit 120.

  When the communication apparatus 100 is on the transmission side, the synchronization signal setting unit 112 sets the synchronization signal pattern acquired by the pattern acquisition unit 111 in the subcarrier modulation unit 320 of the transmission unit 300, thereby serving as a packet destination. A synchronization signal pattern indicating the address of the communication device 100 is added.

  The coefficient setting unit 113 sets the tap coefficient indicating the synchronization signal pattern acquired by the pattern acquisition unit 111 in the matched filter 510 of the timing detection unit 500 when the communication apparatus 100 is the reception side, thereby addressing itself. The symbol timing is detected only when the packet is received.

  Processing performed by such a function realized by the control unit 110 will be described.

  First, “address designation processing” executed when the communication apparatus 100 performs a transmission operation will be described with reference to the flowchart shown in FIG. This process is executed when the control unit 110 inputs transmission target data to the serial / parallel conversion unit 310 of the transmission unit 300 and performs a transmission operation.

  When the process is started, the control unit 110 determines whether or not the packet to be transmitted is a packet for which an address on the receiving side is designated based on a normal communication operation (step S101).

  Here, for example, when transmitting a packet that does not specify the communication device 100 on the receiving side, such as a packet to be transmitted by broadcast, it is not a target for addressing (step S101: No). Transmission is performed by the transmission operation of.

  On the other hand, when transmitting a packet specifying the communication device 100 on the receiving side, since it is a packet to be addressed (step S101: Yes), the pattern acquisition unit 111 accesses the correspondence table in the storage unit 120 and transmits it. A synchronization signal pattern corresponding to the address of the previous communication device 100 is acquired (step S102).

  In this case, the pattern acquisition unit 111 notifies the synchronization signal setting unit 112 of information indicating the acquired synchronization signal pattern. The synchronization signal setting unit 112 sets the subcarrier modulation unit 320 to add the preamble of the notified synchronization signal pattern (phase pattern of the short training symbol and the long training symbol) (step S103), and ends the processing. .

  By such processing, an OFDM signal (modulated signal) to which a synchronization signal pattern corresponding to the address on the receiving side is added is transmitted.

  Next, the “power consumption reduction process” executed when the communication apparatus 100 is the receiving side will be described with reference to the flowchart shown in FIG. This process is executed when the communication apparatus 100 is activated.

  When the process is started, the control unit 110 determines whether an address is assigned to the communication device 100 (step S201). In this case, by determining whether or not the correspondence table as shown in FIG. 10 is stored in the storage unit 120, it is determined whether or not addresses that can be recognized by the communication devices 100 constituting the wireless LAN system 1 are assigned. .

  If no address is assigned to the communication device 100 (step S201: No), it is not possible to perform an operation of distinguishing whether the packet is addressed to itself by the pattern of the synchronization signal. Take action.

  On the other hand, when an address is assigned to the communication device 100 (step S201: Yes), the pattern acquisition unit 111 accesses the correspondence table of the storage unit 120 and corresponds to the address assigned to the communication device 100. A synchronization signal pattern is acquired (step S202).

  In this case, the pattern acquisition unit 111 generates a tap coefficient indicating the synchronization signal from the acquired information indicating the synchronization signal pattern, sets the tap coefficient in the register 512 of the matched filter 510 (step S203), and ends the process. .

  By such processing, the tap coefficient indicating the synchronization signal pattern corresponding to the address on the receiving side is set in the register 512 of the matched filter 510, so that only when the modulation signal to which the synchronization signal pattern is added is received, A signal including a peak value capable of performing symbol timing detection is output from the matched filter 510. That is, whether or not the received packet is addressed to itself is distinguished at the stage of the synchronization process, and only when it is addressed to itself, each process related to demodulation performed after the synchronization process is executed. Processing is not executed. Thereby, the power consumption at the time of receiving operation is reduced.

  As described above, the power consumption of the wireless communication apparatus can be reduced by applying the present invention as in the above embodiment.

  In other words, if wireless communication is a method of establishing high-speed synchronization by using a synchronization signal set in a preamble such as OFDM, it is only necessary to appropriately set a synchronization signal pattern indicating a destination address, thereby reducing power consumption. Can be easily realized.

  In this case, by using a matched filter with a register of tap coefficients that can be arbitrarily set, it is possible to distinguish between packets addressed to the self or when synchronization is established, thus reducing power consumption with an extremely simple configuration. You can plan.

  The said embodiment is an example and the application range of this invention is not restricted to this. That is, various applications are possible, and all embodiments are included in the scope of the present invention.

  For example, in the above-described embodiment, the case where the wireless communication system according to the present invention is realized by a wireless LAN system is exemplified. However, if wireless communication for establishing synchronization using a synchronization signal added as a preamble is performed, wireless communication is performed. The power consumption can be reduced by applying the present invention to any wireless communication system, not limited to a LAN.

  Further, in the above embodiment, the case where OFDM is used as the secondary modulation scheme has been exemplified, but any synchronization signal that can indicate a plurality of types of patterns may be added as a preamble, and the modulation scheme is OFDM. It is not limited.

  In the above embodiment, the case where there is one register in which the tap coefficient is set in the matched filter 510 is illustrated, but a matched filter including a plurality of registers in which a plurality of tap coefficients can be set may be used. According to such a configuration, it is possible to specify a plurality of addresses for one communication device 100 and perform the demodulation operation only when a packet destined for one of the specified addresses is received. it can. Thus, for example, a packet such as a broadcast message in which an address that is not its own address but is included as a reception target can be received. In this case, in the “address designation process” described in the above embodiment, a broadcast address or the like may be processed as an address designation target.

  In the above embodiment, a matched filter in which an arbitrary tap coefficient can be set is used to discriminate whether the packet is addressed to itself. However, discrimination is performed based on a synchronization signal pattern added as a preamble. In this case, the demodulating operation of the received signal may be controlled by a method other than the matched filter. For example, it may be discriminated by performing a matching process between the pattern of the received synchronization signal and the pattern recorded in the correspondence table by logical processing by the control unit 110. In this case, the control unit 110 may control the overall operation of the reception unit 400 to control the demodulation operation according to the distinction result to reduce power consumption.

  Note that, as with the communication device 100 illustrated in the above embodiment, the above-described program executed by the control unit 110 described above can be provided as a receiving device that has a function that can be distinguished from whether it is a packet addressed to itself when synchronization is established. A similar program may be applied to an existing communication device to function as the communication device according to the present invention.

  A method for applying such a program to a communication device is arbitrary. For example, a program acquired via a communication medium such as the Internet can be applied to the communication device, and a communication device that can be read from a recording medium. If so, the program can be recorded and applied to a corresponding recording medium.

It is a figure which shows the structure of the wireless LAN system concerning embodiment of this invention. It is a figure which shows the example of the frame structure of the modulation system which the wireless LAN system shown in FIG. 1 employ | adopts. FIG. 3 is a diagram illustrating a configuration example of a short training symbol and a long training symbol that configure the preamble (synchronization signal) illustrated in FIG. 2. It is a block diagram which shows the structure of the communication apparatus shown in FIG. It is a block diagram which shows the structure of the radio | wireless communication part shown in FIG. It is a block diagram which shows the structure of the synchronous process part shown in FIG. FIG. 7 is a diagram for explaining the timing detection unit illustrated in FIG. 6, in which (a) illustrates a configuration of the timing detection unit, and (b) illustrates an example of an output signal from the matched filter illustrated in (a). Show. It is a figure for demonstrating the structure of a matched filter, (a) shows the structure of the conventional matched filter, (b) is the matched filter concerning this embodiment shown to Fig.7 (a). The structure of is shown. It is a functional block diagram which shows the function implement | achieved by the control part shown in FIG. It is a figure which shows the example of the corresponding | compatible table stored in the memory | storage part shown in FIG. It is a flowchart for demonstrating the "address designation process" concerning embodiment of this invention. It is a flowchart for demonstrating the "power consumption reduction process" concerning embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wireless LAN system, NW ... Main line, 100 ... Communication apparatus, 110 ... Control part, 111 ... Pattern acquisition part, 112 ... Synchronization signal setting part, 113 ... Coefficient setting part,
DESCRIPTION OF SYMBOLS 120 ... Memory | storage part, 200 ... Radio | wireless communication part, 210 ... Antenna, 220 ... Antenna switch, 300 ... Transmission part, 310 ... Serial / parallel conversion part, 320 ... Subcarrier modulation part, 330 ... IFFT part, 340 ... Parallel serial conversion part , 350... RF unit, 400... Reception unit, 410... RF unit, 420... Synchronization processing unit, 421... Quadrature detection unit, 422. FFT unit, 450 ... demodulation unit, 500 ... timing detection unit, 510 ... matched filter, 511 ... register, 512 ... register, 520 ... symbol timing detection unit

Claims (8)

In a wireless communication system including a plurality of communication devices that perform wireless communication by performing reception synchronization with a synchronization signal added by secondary modulation,
The source communication device is
Transmits a modulation signal in which a synchronization signal that is a pattern associated with identification information assigned to a destination communication device is set,
The destination communication device is:
When the received synchronization signal pattern of the modulated signal corresponds to the identification information assigned to the destination communication device, the operation for demodulation of the modulated signal is performed.
A wireless communication system. In a communication apparatus that performs radio communication by performing reception synchronization with a synchronization signal added by secondary modulation,
Receiving means for receiving a modulated signal transmitted by wireless communication;
Discrimination for determining whether or not the pattern of the synchronization signal included in the modulated signal received by the receiving means matches the pattern of the synchronization signal associated with the identification information assigned to the communication device Means,
A demodulating means for performing an operation related to demodulation of the modulated signal received by the receiving means when the discriminating means determines that the patterns of the synchronization signals match;
A communication apparatus comprising: The determination unit is configured by a matched filter including one or more registers whose coefficients are synchronization signals corresponding to identification information assigned to the communication device.
The communication device according to claim 2. Further comprising coefficient setting means for setting a coefficient in a register of the matched filter based on the identification information assigned to the communication device;
The communication apparatus according to claim 3. The synchronization signal is a training symbol added by secondary modulation using orthogonal frequency division multiplexing.
The coefficient setting means sets a coefficient indicating a phase pattern of a short training symbol and a long training symbol, which is associated with the identification information.
The communication apparatus according to claim 4. A transmission means for transmitting a modulated signal including a plurality of subcarriers;
The transmission means adds a synchronization signal having a pattern corresponding to identification information assigned to a transmission destination device to each subcarrier for transmission.
The communication apparatus according to any one of claims 2 to 5, wherein To a computer that controls a communication device that performs radio communication by performing reception synchronization with a synchronization signal added by secondary modulation,
A function for setting a coefficient based on identification information assigned to the communication device in a matched filter register for detecting a received synchronization signal;
A program characterized by realizing. In the computer,
A function of adding a synchronization signal of a pattern corresponding to identification information assigned to a transmission destination device to each subcarrier to a modulation signal to be transmitted;
The program according to claim 7, further comprising:

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