JP2008154095A - Radio communication equipment and radio communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a side robe signal of a subcarrier to which a signal which leaks in a frequency band equivalent to a subcarrier which generates a null signal is assigned as low and to suppress interference given to other radio communication systems. <P>SOLUTION: This radio communication equipment is provided with: a subcarrier signal assignment part 33 which sets null to a subcarrier under use and assigns a modulation signal to an unused subcarrrier; an inverse Fourier transform pert 34 which performs inverse Fourier transform to the respective subcarriers of null and modulation; a guard time addition part 35 which adds guard time to an inverse Fourier transform output signal; a buffer 100 which buffers a guard time added signal; a Fourier transform part 101 which performs Fourier transform to the buffered signal by a scale larger than that of the inverse Fourier transform; a zero signal reproduction part 102 which replaces a signal equivalent to the null subcarrier of the Fourier transformed signal with zero and an inverse Fourier transform part 103 which performs the inverse Fourier transform to the zero replaced signal by the same scale as that of the Fourier transform. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wireless communication apparatus and a wireless communication method, and more particularly to a wireless communication apparatus and a wireless communication method used corresponding to a plurality of wireless communication systems that share and use a predetermined frequency band.

  2. Description of the Related Art Conventionally, a wireless device and a method in which a plurality of wireless communication systems called cognitive radios use a frequency band in common are known (for example, see Non-Patent Document 1). In this type of radio apparatus and method, a radio apparatus with a low priority in an arbitrary radio communication system detects a carrier in a shared frequency band, and the radio apparatus of another radio communication system with a high priority in the frequency band. When it is determined that it is not used, a signal is transmitted.

In addition, in a transmission circuit using a multicarrier modulation scheme such as OFDM (Orthogonal Frequency Division Multiplexing), a null signal is used instead of a subcarrier signal as an input signal corresponding to a band used by another wireless communication system sharing the frequency. A technique for generating and performing multicarrier modulation is known (see, for example, Patent Document 1).
J. Mitola III, “Cognitive Radio for Flexible Mobile Multimedia Communications,” IEEE Sixth International Workshop on Mobile Multimedia Communications (MoMuC'99), pp.3-10, Nov. 1999. Japanese Patent No. 3578966

  In the above-described prior art, when the wireless device continuously transmits two or more OFDM symbols, due to the discontinuity of the signal between the OFDM symbols, the wireless device has a frequency band corresponding to the subcarrier that generated the null signal. The sidelobe signal of the subcarrier to which the signal is assigned leaks, and there is a problem that the amount of interference given to other radio communication systems increases.

  In view of the above-described problems, the present invention provides a side of a subcarrier to which a signal leaking in a frequency band corresponding to a subcarrier that has generated a null signal is allocated even when two or more OFDM symbols are continuously transmitted. It is an object of the present invention to provide a wireless communication apparatus and a wireless communication method capable of transmitting and receiving information while suppressing lobe signals to be low and suppressing interference to other wireless communication systems.

  According to one aspect of the present invention, in a second wireless communication system that shares a frequency with a first wireless communication system that is assigned a predetermined frequency band and performs wireless communication using a plurality of subcarriers. A wireless communication apparatus, wherein a bandwidth of one frequency channel used in the first wireless communication system is equal to a bandwidth of two or more subcarriers of the plurality of subcarriers. A subcarrier allocation control means for determining a carrier bandwidth and a null for both of the two or more subcarriers corresponding to frequency channels in use by the first wireless communication system, and the first Subcarrier signal allocation for allocating modulation signals to the two or more subcarriers corresponding to frequency channels that are not used by any wireless communication system Means, inverse Fourier transform means for respectively performing null Fourier transform and modulation subcarrier output from the subcarrier signal assignment means, and outputting a time signal, and guard time for the time signal. There is provided a wireless communication apparatus comprising a guard time adding means for adding.

  According to another aspect of the present invention, a null is set for a subcarrier corresponding to a frequency channel being used by a first wireless communication system among a plurality of subcarriers, and the first A subcarrier signal allocating means for allocating a modulation signal to any one of the subcarriers corresponding to a frequency channel not used by a radio communication system; a null subcarrier and a modulation subcarrier output from the subcarrier signal allocating means; First inverse Fourier transform means for performing inverse Fourier transform and outputting a plurality of time signals composed of a plurality of symbols, and guard time addition means for adding a guard time to each of the plurality of time signals. Buffering means for buffering the plurality of time signals to which the guard time is added; Fourier transform means for performing Fourier transform on a plurality of time signals buffered in the buffering means, each of which is larger than the scale of the first inverse Fourier transform, and Fourier transformed by the Fourier transform means Zero signal reproduction means for reproducing a zero signal by replacing a subcarrier signal corresponding to the null subcarrier among a plurality of subcarrier signals with zero, and a subcarrier signal substituted with zero by the zero signal reproduction means And a second inverse Fourier transform unit for performing an inverse Fourier transform on the subcarrier signal including the same magnitude as the scale of the Fourier transform by the Fourier transform unit.

  According to another aspect of the present invention, the bandwidth of one frequency channel used in the first wireless communication system is equal to the bandwidth of two or more subcarriers of the plurality of subcarriers. Two or more subcarriers are allocated from among the plurality of subcarriers, and each of the two or more subcarriers corresponding to a frequency channel used by the first wireless communication system is set to null, A modulation signal is assigned to the two or more subcarriers corresponding to frequency channels not used by the first wireless communication system, and a null subcarrier set to null and a modulation sub to which the modulation signal is assigned Each of the carriers is subjected to inverse Fourier transform, and a guard time is added to the time signal subjected to the inverse Fourier transform means. Communication method is provided.

  According to another aspect of the present invention, a null is set for a subcarrier corresponding to a frequency channel being used by a first radio communication system among a plurality of subcarriers, and the first radio A modulation signal is allocated to any of the subcarriers corresponding to a frequency channel not used by the communication system, and a null subcarrier set to null and a modulation subcarrier to which the modulation signal is allocated A first inverse Fourier transform is performed, a guard time is added to each of the plurality of time signals subjected to the first inverse Fourier transform, and the plurality of time signals to which the guard time is added is buffered in a buffer A plurality of time signals buffered in the buffer each have a scale larger than the scale of the first inverse Fourier transform. The zero signal is reproduced by substituting the subcarrier signal corresponding to the subcarrier corresponding to the null subcarrier among the plurality of subcarrier signals subjected to Fourier transform by performing zero transformation, and replaced with zero. There is provided a wireless communication method characterized in that a second inverse Fourier transform having the same scale as the Fourier transform is performed on a subcarrier signal including a subcarrier signal.

  According to the present invention, the power leakage of the sidelobe signal of the modulation subcarrier with respect to the null subcarrier generated due to the signal discontinuity between the symbols in the second wireless communication system can be suppressed to be low. The time signal can be transmitted and received while suppressing the interference to the wireless communication system.

  Hereinafter, a wireless communication device and a wireless communication method according to embodiments of the present invention will be described with reference to the drawings. In addition, while attaching | subjecting the same code | symbol about the same location in each figure, the overlapping description is abbreviate | omitted.

(First embodiment)
FIG. 1 is a diagram showing an example of a schematic configuration of a wireless communication system to which the present invention is applied. The wireless communication device 5 of the present invention corresponds to the wireless communication systems 1 to 4 and other wireless communication systems not shown. The radio communication systems 2 to 4 are first radio communication systems assigned with a predetermined frequency band, and the radio communication system 1 shares a frequency with these radio communication systems 2 to 4. It is the 2nd radio | wireless communications system which performs radio | wireless communication using a some subcarrier.

  The communication systems or types of the wireless communication systems 2 to 4 are, for example, a W-CDMA (Wideband-Code Division Multiple Access) system, a PDC (Personal Digital Cellular) system or a GSM (Global Standard for Mobile Communication system). Alternatively, a MAN (Metropolitan Area Network) such as IEEE802.16e or a LAN (Local Area Network) such as IEEE80211, or a marine radio, a radar, or a fixed microwave system. The wireless communication systems 2 to 4 may be configured not only as systems capable of bidirectional wireless communication but also as wireless systems such as TV broadcasting.

  The communication method or communication standard of the wireless communication system 1 is a method or standard that can share the frequency used by the above-described communication method or types of wireless communication systems 2 to 4, and a newly established method or standard is also used. Can do.

  In addition, the wireless communication system 2 exists in a position geographically overlapping with the wireless communication system 1, but as shown as the wireless communication system 3, it seems to exist in a place geographically separated from the wireless communication system 1. Is also possible.

  When the wireless communication device 5 belonging to the wireless communication system 1 performs wireless communication sharing the frequency band with the wireless communication system 2, the wireless communication device 5 has the priority of the wireless communication system 1 as the wireless communication. It has data that is lower than the priority of system 2. That is, the wireless communication device 5 is permitted to use the frequency under the priority condition.

  In this case, the wireless communication device 5 should not interfere with the wireless communication performed by the wireless communication device (or wireless device) 6 belonging to the wireless communication system 2. FIG. 2 shows an arrangement example of a plurality of frequency channels in the frequency band assigned to each of the radio communication systems 2 and 3. The radio communication system 2 is assigned a frequency band 10, and a plurality of frequency channels B 1, B 2, B 3, B 4, B 5..., Bi (i = 12, 13, 14, 15, 16, ..., 17) are included. The wireless communication system 3 is assigned a frequency band 11, and a plurality of frequency channels C 1, C 2,..., Cj (j = 18, 19, 20,..., 21, 22 are included in the frequency band 11. ) Is included.

  The wireless communication device 5 belonging to the wireless communication system 1 shown in FIG. 1 uses, for example, the frequency channels 13, 14, 15 and 16 of FIG. The communication system 1 is permitted to use these frequency channels with a lower priority than the wireless communication system 2. For this reason, the radio communication device 5 belonging to the radio communication system 1 transmits signals at a frequency corresponding to the frequency channel 14 when the radio communication device 6 belonging to the radio communication system 2 uses, for example, the frequency channel 14. As a result, the wireless communication device 5 does not interfere with the wireless communication performed by the wireless communication device 6 using the frequency channel 14.

  That is, the wireless communication device 5 uses two or more frequency channels of the wireless communication system sharing the frequency at the same time, but when the wireless communication system with a high priority starts using the frequency channel, The communication of the radio communication system 1 is continued by transmitting the signal only in the frequency channel that is determined not to be used without transmitting the signal in the frequency channel.

  The description using FIG. 1 and FIG. 2 is for the examples of the wireless communication systems 2 to 4 as the wireless communication system in which the wireless communication system 1 shares the frequency band, but the wireless communication system 1 shares the frequency band. There is no particular limitation on the number of wireless communication systems to be used. The wireless communication system 1 may share frequencies with other wireless communication systems different from the wireless communication systems 2 and 3 and the wireless communication system 4. As an example, the wireless communication system 1 can share frequencies with six wireless communication systems. In the following description, when the radio communication system 1 shares frequency with six radio communication systems, these six radio communication systems may be represented as radio communication systems B to G. For example, the wireless communication system B is a W-CDMA system, the wireless communication system C is a wireless LAN system compliant with IEEE802.11a, the wireless communication system D is a wireless LAN system compliant with IEEE802.11b, and the wireless communication system E is a PDC. If the wireless communication system F is a radar system and the wireless communication system G is a TV broadcast, the wireless communication system 1 may share frequencies with these wireless communication systems B to G. .

  Even when the wireless communication system 1 shares the frequency band with the wireless communication systems D and E, the wireless communication system 1 uses the frequency band with lower priority than the wireless communication system D and the wireless communication system E. Allowed.

  Further, although the wireless communication device 5 has a function as a wireless base station and a function as a wireless terminal station, the wireless communication device 5 may be configured to be separately distinguished from a wireless base station and a wireless terminal station. .

  Hereinafter, an example in which the wireless communication system 1 illustrated in FIG. 1 performs wireless communication by sharing the frequency with the wireless communication system 2 illustrated in FIG. 1 will be described. The case where the wireless communication system 1 shares frequencies with the six wireless communication systems B to G is the same as the wireless communication system 2.

  As illustrated in FIG. 3, the wireless communication device 5 according to the first embodiment of the present invention includes a transmission / reception unit 30, a control unit 31, and a memory 32.

  The transmission / reception unit 30 generates an OFDM symbol using a plurality of subcarriers, and includes a subcarrier signal allocation unit 33, an inverse Fourier transform unit 34, and a guard time addition unit 35.

  The subcarrier signal allocating unit 33 sets null for two or more subcarriers corresponding to the frequency channel being used by the wireless communication system 2 and corresponds to a frequency channel not used by the wireless communication system 2 The modulation signal is assigned to two or more subcarriers. In this subcarrier signal allocating unit 33, a transmission bit string is mapped to each subcarrier based on a desired modulation scheme, and null (“0”) is a frequency channel of the radio communication system 2 that shares the frequency. Is set to a subcarrier corresponding to a frequency channel determined to be used.

  The inverse Fourier transform unit 34 performs inverse Fourier transform on the null subcarrier and the modulated subcarrier output from the subcarrier signal allocation unit 33, and outputs one or a plurality of time signals.

  The guard time adding unit 35 adds a guard time to each time signal or signal waveform subjected to the inverse Fourier transform process in the inverse Fourier transform unit 34.

  The control unit 31 determines the bandwidth of the subcarrier so that the bandwidth of one frequency channel used in the wireless communication system 2 is equal to the bandwidth of two or more subcarriers among the plurality of subcarriers. Subcarrier allocation control means. The control unit 31 determines the total number of subcarriers, the scale of inverse Fourier transform, the guard time length and the modulation method, and based on the determined total number of subcarriers, the scale of inverse Fourier transform, the guard time length and the modulation method, The transceiver 30 is controlled. The cell radius and the amount of data to be transmitted / received are input to the control information input terminal of the control unit 31 by a user operation.

  The memory 32 stores a table or table data necessary for the control unit 31 to determine the length of the guard time. In addition, when the wireless communication system 1 shares frequencies with the six wireless communication systems B to G, this table stores data representing the frequency channels and reception quality for the wireless communication systems B to G. (FIG. 5 etc. which will be described later). As the memory 32, a ROM, a RAM, or the like is used.

  Note that the functions of the subcarrier signal allocation unit 33, the inverse Fourier transform unit 34, the guard time addition unit 35, and the control unit 31 are all realized by a CPU, ROM, RAM, IC, and LSI.

  Accordingly, in the wireless communication method according to the present embodiment, the bandwidth of one frequency channel used by the wireless communication apparatus 5 in the wireless communication system 2 is the bandwidth of two or more subcarriers among a plurality of subcarriers. So that two or more subcarriers are allocated from a plurality of subcarriers, and null is set for each of the two or more subcarriers corresponding to the frequency channel being used by the wireless communication system 2. The modulation signal is allocated to two or more subcarriers corresponding to frequency channels not used by the wireless communication system 2, and the null subcarrier set to null and the modulation subcarrier to which the modulation signal is allocated are assigned. On the other hand, inverse Fourier transform is performed, and a guard time is added to the time signal subjected to the inverse Fourier transform means.

  The operation of signal transmission processing in the wireless communication apparatus 5 according to this embodiment will be described with such a configuration.

  An example of processing in which the wireless communication device 5 transmits a signal will be described in detail with reference to the flowchart of FIG. The control unit 31 in FIG. 3 determines one of the radio communication systems sharing the frequency (step S40). Here, it is assumed that the radio communication system 2 is selected as a system in which the radio communication system 1 shares a frequency.

  Subsequently, in step S41, the radio communication device 5 determines the number of subcarriers for multicarrier communication performed in the radio communication system 1 corresponding to one frequency channel of the radio communication system 2 in which the radio communication system 1 shares a frequency. However, in order for the wireless communication device 5 to appropriately receive a signal based on the reception sensitivity, the bandwidth of one frequency channel of the wireless communication system 2 is the bandwidth of two or more subcarriers of the wireless communication system 1 Set to be For example, the control unit 31 sets the number of subcarriers of the wireless communication system 1 to be equal to the bandwidth of one frequency channel of the wireless communication system 2 as eight. At this time, if the bandwidth of one frequency channel of the wireless communication system 2 is 20 MHz, the bandwidth of one subcarrier of the wireless communication system 1 is 20 MHz / 8 = 2.5 MHz.

  In step S41, after the control unit 31 determines the number of subcarriers for multicarrier communication performed in the wireless communication system 1 corresponding to one frequency channel of the wireless communication system 2 in which the wireless communication system 1 shares a frequency, control is performed. The unit 31 determines the total number of subcarriers (signal bandwidth in the wireless communication system 1) of multicarrier communication performed by the wireless communication system 1 (step S42).

  In step S <b> 42, the control unit 31 determines the total number of subcarriers so that the wireless communication system 1 shares two or more frequency channels of the wireless communication system 2. For example, when the control unit 31 sets the number of subcarriers of the wireless communication system 1 to be equal to the bandwidth of one frequency channel of the wireless communication system 2, all the subcarriers are set to 16 or more. The As another example, when the total number of subcarriers of multicarrier communication performed by the wireless communication system 1 is set to 64, the wireless communication system 1 shares 64/8 = 8 frequency channels of the wireless communication system 2. Become.

In step S42, when the control unit 31 determines the total number of subcarriers for multicarrier communication, the scale of the inverse Fourier transform performed by the inverse Fourier transform unit 34 (the scale of the first Fourier transform) is determined (step S43). As the scale of the inverse Fourier transform, the smallest integer that is a power of 2 greater than or equal to the total number of subcarriers determined in step S42 is selected. That is, when the total number of subcarriers is k and n is an integer equal to or greater than 1, the scale s of the inverse Fourier transform is
s = min (2 ⁿ ≧ k) Formula (1)
Is required. For example, when the total number of subcarriers is determined to be 48, the scale of the inverse Fourier transform is determined to be 64, and when the total number of subcarriers is determined to be 256, the scale of the inverse Fourier transform is 256. Is determined.

  When determining the scale of the inverse Fourier transform, the control unit 31 determines the length of the guard time based on the information described in the memory 32 (step S44). The information described in the memory 32 is information such as “the guard time length is, for example, 1/4 of the effective OFDM symbol length”. When the guard time length is 1/4 of the effective OFDM symbol length and the scale of the inverse Fourier transform is 64, the guard time length is 64 × (1/4) = 16. When determining the length of the guard time, the control unit 31 determines the modulation method (step S45). The modulation scheme is, for example, a modulation scheme such as QPSK, 16QAM, or 64QAM.

  When the control unit 31 determines the total number of subcarriers, the scale of inverse Fourier transform, the guard time length, and the modulation method, the transmission / reception unit 30 determines the total number of subcarriers, the scale of inverse Fourier transform, and the guard time length. The modulation scheme is output, the total number of subcarriers and the modulation scheme are set in the subcarrier signal allocation section 33, the scale of the inverse Fourier transform is set in the inverse Fourier transform section 34, and the guard time length is set in the guard time adding section 35. Set to.

  The subcarrier signal allocating unit 33 maps the transmission bit string input from the input terminal to each subcarrier based on the modulation scheme input or set from the control unit 31, and controls the control unit 31 from the control information input terminal. Sub-channels corresponding to frequency channels determined to be used among a plurality of frequency channels of the wireless communication system 2 sharing the frequency based on information (for example, cell radius and transmission / reception data amount) input via Null ("0") is set without mapping the transmission bit string to the carrier (step S46).

  Here, mapping of the transmission bit string to each subcarrier refers to a phase in which the transmission bit string is represented by an in-phase component (I phase) and a quadrature component (Q phase) based on the modulation method input from the control information input terminal. This is a process of converting into signal points on a plane (IQ phase plane). For example, in the QPSK modulation process, when the input bit string is “11”, a signal point is mapped to (1, 1) on the IQ phase plane, and when the input bit string is “10”, the signal point is on the IQ phase plane. When the signal point is mapped to (1, -1) and the input bit string is "00", the signal point is mapped to (-1, -1) on the IQ phase plane and the input bit string is "01". In some cases, a signal point is mapped to (-1, 1) on the IQ phase plane.

  Also, the process of setting null without mapping the transmission bit string to the subcarrier is a process of mapping the signal point to (0, 0) on the IQ phase plane.

  The inverse Fourier transform of the scale input from the control unit 31 is performed by the inverse Fourier transform unit 34 on the signal to which the modulation signal and null are assigned by the subcarrier signal assignment unit 33 (step S47). The guard time adding unit 35 adds a guard time to the inverse Fourier transformed signal (step S48), and the signal is output from the output terminal. The guard time addition process is a process of copying the signal in the latter half of the inverse Fourier transformed signal to the head part.

  After the signal is output from the output terminal in step S48, the control unit 31 determines whether or not to end the communication (step S49). If the communication is continued, the processing from step S46 is repeated, for example, When a communication termination request is input from the user, a communication termination process is performed (step S50), and the communication is terminated. The communication end process (step S50) is, for example, a process of transmitting a connection disconnection request to the radio base station if it is a radio terminal station.

  As described above, the wireless communication device 5 is configured such that the bandwidth of one frequency channel of the wireless communication system 2 sharing the frequency is equal to the bandwidth of the subcarrier of the multicarrier signal that is communicated in the wireless communication system 1. When the sub-carrier corresponding to the frequency channel being used by the wireless communication system 2 is set to null by selecting it to be equal to the bandwidth of two or more sub-carriers of one multi-carrier signal, the null sub-carrier Since the leakage signal of the sidelobe signal from the other subcarriers to the null subcarrier can be kept low, interference with the frequency channel in use of the wireless communication system 2 can be kept low. Further, in multicarrier communication performed in the wireless communication system 1, subcarriers adjacent to the frequency channel being used by the wireless communication system 2 may be set to null.

(Details of selection method of radio communication system sharing frequency)
When the wireless communication device 5 selects a wireless communication system that shares a frequency from the wireless communication systems B to G, the wireless communication device 5 refers to a table held in the memory 32.

  FIG. 5 is a diagram showing an example of a table held in the memory 32 of the wireless communication apparatus 5 shown in FIG. The table shown in FIG. 5 shows the wireless communication systems B to G for the wireless communication systems B, G, C, D, E, F, G. System bandwidth, which is the total frequency bandwidth allocated to the one, the bandwidth of one frequency channel, the number of frequency channels, the carrier frequency of the signal, and uniform reception quality in all the predetermined wireless communication systems B to G The minimum reception sensitivity representing the reception power to be satisfied is stored. Here, it is assumed that the wireless communication system 1 selects any one or a plurality of wireless communication systems that share a frequency from among the six wireless communication systems from the wireless communication system B to the wireless communication system G.

  6 shows a process (step S40) for determining a radio communication system sharing a frequency based on the table shown in FIG. 5 in the transmission flowchart of the signal transmission process shown in FIG. 4 performed by the radio communication apparatus 5 (FIG. 3). It is a flowchart for demonstrating an example of this detailed process. The control unit 31 in FIG. 3 determines the cell radius of wireless communication performed in the wireless communication system 1 (step S51).

  If the communication is performed in a personal area with a cell radius of, for example, 10 m or less, the wireless communication device 5 uses a wireless communication system C and a wireless communication system F that share a high carrier frequency based on the table shown in FIG. A communication system candidate is set (step S54). If the communication is performed in a local area with a cell radius of about 10 to 100 m, the wireless communication device 5 uses the table shown in FIG. Let it be a candidate for a shared wireless communication system (step S53). If the communication has a cell radius of 100 m or more, the wireless communication device 5 is a candidate for a wireless communication system sharing the wireless communication system E and the wireless communication system G having a low carrier frequency based on the table shown in FIG. (Step S52). As described above, the wireless communication device 5 selects a candidate wireless communication system to be shared based on the characteristic that the propagation distance becomes longer as the carrier frequency is lower.

  In step S51, when the wireless communication system E and the wireless communication system G become candidates for the shared wireless communication system, the total required throughput of each user of the wireless communication device 5 is determined (step S55). For example, when it is larger than 10 Mbps, the wireless communication device 5 passes the route labeled “greater than 10 Mbps”, and the wireless communication device 5 uses the table shown in FIG. The wireless communication system to be shared is selected (step S58). When the total requested throughput of each user is within 10 Mbps, the wireless communication device 5 passes the route labeled “within 10 Mbps” and the wireless communication device 5 has a higher system bandwidth than the wireless communication system G based on the table shown in FIG. The narrow wireless communication system E is selected as a wireless communication system sharing a frequency (step S59).

  If the wireless communication system B and the wireless communication system D become candidates for the wireless communication system shared by the wireless communication system B and the wireless communication system D in step S51, the total required throughput of each user is similarly determined (step S56). For example, if it is larger than 10 Mbps, based on the table shown in FIG. 5, the wireless communication device 5 selects the wireless communication system B having a wide system bandwidth as the wireless communication system sharing the frequency (step S60). When the total requested throughput of each user is within 10 Mbps, the wireless communication system D having a narrower system bandwidth than the wireless communication system B is selected as the wireless communication system sharing the frequency based on the table shown in FIG. (Step S61).

  In step S51, when the wireless communication system C and the wireless communication system F are candidates for the wireless communication system to be shared, the total required throughput of each user is similarly determined (step S57). For example, if it is larger than 10 Mbps, the wireless communication system F having a wide system bandwidth is selected as a wireless communication system sharing the frequency based on the table shown in FIG. 5 (step S62). When the total requested throughput of each user is within 10 Mbps, the wireless communication system C having a narrower system bandwidth than the wireless communication system F is selected as the wireless communication system sharing the frequency based on the table shown in FIG. (Step S63).

  As described above, the wireless communication device 5 selects the wireless communication system that is optimal for the communication of the wireless communication system 1 by selecting the wireless communication system that shares the frequency based on the sum of the carrier frequency and the requested throughput of the user. can do.

(Details on how to determine the number of subcarriers per frequency channel)
FIG. 7 is a signal transmission flowchart shown in FIG. 4 performed by the wireless communication apparatus 5 shown in FIG. 3, and the number of subcarriers per frequency channel of the wireless communication system sharing the frequency based on the table shown in FIG. It is a flowchart for demonstrating an example of the detailed process of the process (step S41) which determines. After determining the radio communication system sharing the frequency, the control unit 31 in FIG. 3 sets the minimum reception sensitivity of the radio communication system sharing the frequency to a predetermined threshold value based on the table shown in FIG. Comparison is performed (step S70). If the minimum reception sensitivity is smaller than −100 dBm, for example, it is determined that the bandwidth of one frequency channel of the radio communication system sharing the frequency corresponds to 16 subcarriers of the radio communication system 1 (step S71). On the other hand, if the minimum reception sensitivity is −100 dBm or more and less than −80 dBm, the bandwidth of one frequency channel of the radio communication system sharing the frequency is determined to correspond to 8 subcarriers of the radio communication system 1. (Step S72). Further, if the minimum reception sensitivity is −80 dBm or more, it is determined that the bandwidth of one frequency channel of the radio communication system sharing the frequency corresponds to four subcarriers of the radio communication system 1 (step S73). ).

  In this way, since the lower the minimum reception sensitivity of the radio communication system sharing the frequency, the weaker the interference is. Therefore, by setting a larger number of subcarriers corresponding to one frequency channel, the plurality of subcarriers can be set. Interference to frequency channels in use in a wireless communication system that shares frequencies by keeping the leakage of sidelobe components from subcarriers assigned signals to multiple null subcarriers low. Can be reduced.

(Details on how to determine the total number of subcarriers (1))
8 shows the total number of subcarriers (the signal bandwidth in the wireless communication system 1) of the multicarrier communication performed by the wireless communication system 1 in the signal transmission flowchart shown in FIG. 4 performed by the wireless communication apparatus 5 shown in FIG. It is a flowchart for demonstrating an example of the detailed process of the process (step S42) to determine. In steps S81 to 83 and S85 to 87 of FIG. 8, “L” represents the number of subcarriers per frequency channel of the wireless communication system in which the wireless communication system 1 shares the frequency. The control unit 31 in FIG. 3 determines the cell radius of radio communication performed in the radio communication system 1 after determining the number of subcarriers per frequency channel of the radio communication system sharing the frequency (step S80).

  If the communication is performed in a personal area with a cell radius of, for example, 10 m or less, the wireless communication device 5 determines M = 4L as a candidate for the total number of subcarriers based on only the cell radius (step S83). . If the communication is in a local area with a cell radius of about 10 to 100 m, the wireless communication device 5 determines M = 8L as the candidate “M” for the total number of subcarriers based only on the cell radius (step S82). If the communication has a cell radius of 100 m or more, the wireless communication device 5 determines M = 16L as a candidate for the total number of subcarriers based only on the cell radius (step S81).

  Thus, the larger the cell radius, the higher the probability that the wireless communication system that shares the frequency at the position of the wireless communication device 5 that performs wireless communication of the wireless communication system 1 uses the frequency channel. This is because communication is continued by transmitting and receiving signals in frequency channels other than the frequency channel even when the shared wireless communication system starts using the frequency channel by sharing the frequency channel.

  In step S81, step S82, and step S83, after determining the candidate “M” for the total number of subcarriers based only on the cell radius, the wireless communication device 5 determines the total required throughput of each user (step S84). . For example, if it is greater than 100 Mbps, the wireless communication device 5 determines the final total number of subcarriers “N” as N = 32M (step S85). If the total requested throughput of each user is, for example, 10 Mbps or more and smaller than 100 Mbps, N = 16 M is determined (step S86). On the other hand, when the total requested throughput of each user is within 10 Mbps, for example, N = 4M is determined (step S87).

  Thus, as the total required throughput is larger, a higher signal transmission rate is required, and more subcarriers are used to realize a higher signal transmission rate.

(Details on how to determine the total number of subcarriers (2))
9 shows the total number of subcarriers (the signal bandwidth in the wireless communication system 1) of multicarrier communication performed by the wireless communication system 1 in the signal transmission flowchart shown in FIG. 4 performed by the wireless communication apparatus 5 shown in FIG. FIG. 9 is a flowchart for explaining an example of detailed processing of processing to be determined (step S42), showing an embodiment different from the flowchart shown in FIG. In FIG. 9, “L” represents the number of subcarriers per frequency channel in the wireless communication system in which the wireless communication system 1 shares a frequency, as in FIG. 8. The control unit 31 in FIG. 3 determines the real-time property of the application or the communication application after determining the number of subcarriers per frequency channel of the wireless communication system sharing the frequency (step S90).

  When the application has a non-real time characteristic such as file transfer, the control unit 31 subsequently determines the total required throughput of each user (step S91). For example, if it is within 50 Mbps, the control unit 31 determines that the final total number of subcarriers “N” is N = 32L (step S92). If the total requested throughput of each user is greater than 50 Mbps, N = 64L is determined (step S93).

  On the other hand, when the application has real-time properties such as voice call, videophone, and moving image transmission, the delay time request is determined (step S94). For example, when the delay time request is 100 microseconds or less, N = 4L is determined (step S95). If the delay time request is greater than 100 microseconds in step S94, the total requested throughput of each user is determined (step S96). For example, if it is within 50 Mbps, the final total number of subcarriers “N” is determined as N = 16L (step S97). If the total requested throughput of each user is greater than 50 Mbps, N = 32L is determined (step S98).

  As the total number of subcarriers increases, the processing delay of Fourier transform when receiving signals increases, but in this way, if the application has real-time characteristics, the delay time requirement can be reduced by reducing the total number of subcarriers. Can be met.

(Second Embodiment)
FIG. 10 is a schematic block diagram of a wireless communication device 5A according to the second embodiment of the present invention. The wireless communication device 5A according to the present embodiment includes a transmission / reception unit 30A. The transmission / reception unit 30A includes a buffering unit 100, a Fourier transform unit 101, and a zero signal reproduction unit in addition to the transmission / reception unit 30 of the wireless communication device 5 of FIG. 102 and a second inverse Fourier transform unit 103 are added.

  The subcarrier signal allocating unit 33 sets a null for a subcarrier corresponding to a frequency channel used by the wireless communication system 2 among the plurality of subcarriers, and is not used by the wireless communication system 2 The modulation signal is also assigned to any of the subcarriers corresponding to.

  The inverse Fourier transform unit 34 performs inverse Fourier transform on the null subcarrier and the modulated subcarrier output from the subcarrier signal allocation unit 33, and outputs a plurality of time signals composed of two or more OFDM symbols. The first inverse Fourier transform means.

  The guard time adding unit 35 adds a guard time to each of a plurality of time signals output after being subjected to inverse Fourier transform by the inverse Fourier transform unit 34.

  The buffering unit 100 buffers a plurality of time signals to which guard times are added.

  The Fourier transform unit 101 performs Fourier transform on a plurality of time signals buffered in the buffering unit 100, each having a scale larger than the scale of the first inverse Fourier transform.

  The zero signal reproduction unit 102 reproduces a zero signal by replacing a subcarrier signal corresponding to a null subcarrier among a plurality of subcarrier signals Fourier-transformed by the Fourier transform unit 101 with zero.

  The second inverse Fourier transform unit 103 performs inverse Fourier transform on the subcarrier signal including the subcarrier signal that has been replaced with zero by the zero signal reproduction unit 102, in the same scale as the Fourier transform performed by the Fourier transform unit 101. Second inverse Fourier transform means.

  Other than these, the same parts as those in FIG. The functions of the buffering unit 100, the Fourier transform unit 101, the zero signal reproduction unit 102, and the second inverse Fourier transform unit 103 are realized by a CPU, ROM, RAM, IC, and LSI.

  Thereby, in the radio communication method according to the present embodiment, the radio communication device 5A sets a null to the subcarrier corresponding to the frequency channel used by the radio communication system 2 among the plurality of subcarriers. The modulation signal is allocated to any subcarrier corresponding to a frequency channel not used by the communication system 2, and the null subcarrier set to null and the modulation subcarrier to which the modulation signal is allocated The first inverse Fourier transform is performed, a guard time is added to each of the plurality of time signals subjected to the first inverse Fourier transform, the added plurality of time signals are buffered in a buffer, and the buffering unit 100 A Fourier transform having a larger scale than the scale of the first inverse Fourier transform is performed on each of the plurality of ringed time signals. A zero signal is reproduced by substituting the subcarrier signal corresponding to the subcarrier corresponding to the null subcarrier among the plurality of subcarrier signals subjected to the Rie transform with zero, and the subcarrier signal including the subcarrier signal replaced with zero A second inverse Fourier transform having the same scale as the Fourier transform is performed on the carrier signal.

  With this configuration, the signal transmission processing operation of the wireless communication device 5A in the wireless communication system 1 according to the present embodiment will be described.

  FIG. 11 is a flowchart for explaining an example of a signal transmission process of the wireless communication device 5A shown in FIG. The control part 31 of FIG. 10 determines the radio | wireless communications system which shares a frequency (step 110). Here, it is assumed that the radio communication system 2 is selected as a system in which the radio communication system 1 shares a frequency.

  Subsequently, similarly to step S41 in FIG. 4, the wireless communication device 5A is a subcarrier for multicarrier communication performed in the wireless communication system 1 corresponding to one frequency channel of the wireless communication system 2 in which the wireless communication system 1 shares a frequency. Although the number of carriers is determined, the bandwidth of one frequency channel of the wireless communication system 2 is set to be the bandwidth of two or more subcarriers of the wireless communication system 1 (step S111).

  After determining the number of subcarriers for multicarrier communication performed in the wireless communication system 1 corresponding to one frequency channel of the wireless communication system 2 in which the wireless communication system 1 shares a frequency in step S111, the control unit 31 in FIG. 4, the total number of subcarriers (the signal bandwidth in the wireless communication system 1) of the multicarrier communication performed by the wireless communication system 1 is determined as in step S42 in FIG. The total number of subcarriers is determined so that two or more frequency channels are shared (step S112).

  When the control unit 31 determines the total number of subcarriers for multicarrier communication in step S112, the scale of the inverse Fourier transform (scale of the first Fourier transform) performed by the inverse Fourier transform unit 35 is determined as in step S43 of FIG. Determine (step S113). When determining the scale of the inverse Fourier transform, the control unit 31 determines the length of the guard time based on the information described in the memory 32 as in step S44 of FIG. 4 (step S114). When determining the length of the guard time, the control unit 31 determines the modulation method (step S115). After determining the modulation scheme in step S115, the control unit 31 determines the number of OFDM symbols to be buffered by the buffering unit 100 in FIG. 10 (step S116). Here, the number of OFDM symbols to be buffered is the number of OFDM symbols constituting one frame or one packet, and is two or more OFDM symbols.

  When the number of OFDM symbols to be buffered is determined in step S116, the scale of Fourier transform and inverse Fourier transform (scale of the second Fourier transform) performed in the Fourier transform unit 101 and the second inverse Fourier transform unit 103 in FIG. 10 is determined. (Step S117). The magnitude of the second Fourier transform is selected to be an integer that is not less than the total number of samples of the buffered signal and is a power of 2. For example, if the total number of samples in the buffered signal is 800 samples, a scale of 1024 points is selected.

  When the control unit 31 determines the total number of subcarriers, the scale of inverse Fourier transform, the guard time length, the modulation scheme, the number of OFDM symbols to be buffered, and the scale of the second Fourier transform, the total number of subcarriers determined by the transmission / reception unit 30A And the scale of the inverse Fourier transform, the guard time length, the modulation method, and the scale of the second Fourier transform, respectively. Further, the control unit 31 sets the total number of subcarriers and the modulation scheme in the subcarrier signal allocation unit 33, sets the inverse Fourier transform scale in the inverse Fourier transform unit 34, and sets the guard time length to the guard time adding unit 35. , The number of OFDM symbols to be buffered is set in the buffering unit 100, and the scale of the second Fourier transform is set in the Fourier transform unit 101 and the second inverse Fourier transform unit 103, respectively.

  The subcarrier signal allocating unit 33 maps the transmission bit string input from the input terminal to each subcarrier based on the modulation scheme input from the control unit 31 and from the control information input terminal via the control unit 31. Null (“0”) without mapping the transmission bit string to the subcarrier corresponding to the frequency channel determined to be used among the frequency channels of the radio communication system 2 sharing the frequency based on the input information. ) (Step S118). The inverse Fourier transform of the scale input from the control unit 31 is performed by the inverse Fourier transform unit 34 on the signal to which the modulation signal and the null are assigned by the subcarrier signal assignment unit 33 (step S119). The guard time adding unit 35 adds a guard time to the inverse Fourier transformed signal (step S120), and the buffering unit 100 combines the buffered and serial signals (step S121).

  The buffering unit 100 determines whether data corresponding to the specified number of OFDM symbols set by the control unit 31 is buffered (step S122). If the buffered unit 100 is not buffered for the specified number of OFDM symbols. , The process from step S118 to step S121 is repeated until a predetermined number of OFDM symbols are buffered through the No route. If buffering is performed for the prescribed number of OFDM symbols in step S122, the Fourier transform unit 101 performs a Fourier transform of the scale input from the control unit 31 (step S123).

In step S123, the signal subjected to the Fourier transform by the Fourier transform unit 101 is input to the zero signal reproducing unit 102, and set to the null subcarrier by the subcarrier signal allocation unit 33 (the same process as the process in step S118). The corresponding subcarrier value is set to “0” again (step S124). Note that the subcarrier number set as the null subcarrier by the subcarrier signal allocation unit 33 is input from the control unit 31. Here, the scale of the first Fourier transform is 2 ^p (p is an integer greater than 0), the scale of the second Fourier transform is 2 ^{p + q} (q is an integer greater than 0), and k before the first Fourier transform. If the first subcarrier is set to null, the position (th) of the subcarrier or subcarrier to be reset to null in step S123 is
k × 2 ^q −2 ^q−1 to k × 2 ^q + (2 ^q−1 −1) Formula (2)
It becomes. For example, when the scale of the first Fourier transform is 64 and the scale of the second Fourier transform is 1024, the subcarrier signal allocation unit 33 sets the eighth and ninth subcarriers to null. Then, the subcarriers reset to null by the zero signal reproducing unit 102 are the 120th to 151st subcarriers. In step S123, the signal for which null has been reset is input to the second inverse Fourier transform unit 103, and the second inverse Fourier transform unit 103 performs the inverse Fourier transform of the scale input from the control unit 31. (Step S125), output from the output terminal. After the signal is output from the output terminal in step S125, it is determined whether or not to end the communication (step S49). If the communication is continued, the process from step S118 to step S125 is performed through the No route. Repeatedly, for example, when a communication termination request is input from the user, the communication termination process is performed through the Yes route (step S50), and the communication is terminated. The communication end process (step S50) is, for example, a process of transmitting a connection disconnection request to the radio base station if it is a radio terminal station.

  FIGS. 12A to 12G are diagrams for explaining the zero signal reproduction process, and an example of the process output of the flowchart shown in FIG. 11 is displayed. In FIG. 12, the scale of the first Fourier transform is set to 64, the scale of the second Fourier transform is set to 1024, the guard time is set to 1/4 of the effective OFDM symbol length, and the OFDM symbols to be buffered are set to 10 symbols. Is shown.

  A signal waveform 110 shown in FIG. 12A represents an example of processing in one OFDM symbol when the modulation scheme is QPSK, and the eighth and ninth subcarriers are set to null. The subcarrier signal allocation in FIG. 11 (corresponding to step S118) is shown.

  A signal waveform 111 shown in FIG. 12B represents an in-phase component signal as a result of performing a 64-point complex inverse Fourier transform on the signal waveform 110 (inverse Fourier transform, step in FIG. 11). Equivalent to S119).

  A signal waveform 112 shown in FIG. 12C represents a signal waveform obtained by adding a guard time of 16 samples to the signal waveform 111 (addition of the guard time in FIG. 11, corresponding to step S120).

  A signal waveform 113 shown in FIG. 12D represents a signal of in-phase components of four OFDM symbols among signals obtained by buffering and combining 10 OFDM symbols (buffering, step of FIG. 11). Equivalent to S121).

  The signal waveform 114 shown in FIG. 12E is obtained by performing the 1024-point complex Fourier transform on the signal obtained by buffering and combining 10 OFDM symbols, and the square of the in-phase component and the quadrature component. A waveform summed with the square is represented (Fourier transform in FIG. 11, corresponding to step S123).

  The signal waveform 115 shown in FIG. 12F is the eighth and ninth subcarriers of the signal waveform 110 of the in-phase component signal and the quadrature component signal after performing the Fourier transform (step S123) in FIG. 11 represents the waveform of the sum of the square of the in-phase component and the square of the quadrature component obtained as a result of resetting the 120th to 151st subcarriers corresponding to (0). , Corresponding to step S124).

  The signal waveform 116 shown in FIG. 12 (g) is a result of the second complex inverse Fourier transform (the second inverse Fourier transform in FIG. 11, corresponding to step S125) of the in-phase and quadrature component signals reproduced from the zero signal. Represents the signal of the in-phase component.

  Each of the four OFDM symbols is a time waveform obtained by performing an inverse Fourier transform process (FIG. 12 (d)), but waveform discontinuities occur between the OFDM symbols. The wireless communication device 5A according to the present embodiment performs inverse Fourier transform on the time waveform having this discontinuity to obtain a spectrum waveform (FIG. 12 (e)), and in the frequency bands of the 120th to 151st subcarriers. The resulting spectral leakage is removed (FIG. 12 (f)). Then, the wireless communication device 5A performs inverse Fourier transform again on the waveform from which the leakage component of the spectrum is removed to generate a time waveform (FIG. 12 (g)). As a result, a time waveform having no spectral leakage component caused by a break in the time waveform is obtained.

  As described above, since the side lobe component of the subcarrier to which the signal is assigned can suppress the power leaked to the null subcarrier due to the discontinuity of the connection point between OFDM symbols, the frequency is shared. Interference with the frequency channel during use of the wireless communication system can be kept low.

(First Modification of Second Embodiment)
An example when interleaving is included will be described.

  FIG. 13 is a schematic block diagram of a wireless communication device 5B according to a first modification of the second embodiment of the present invention. The wireless communication device 5B according to this modification includes a transmission / reception unit 30B, and the transmission / reception unit 30B has a configuration in which an interleaving unit 120 is added to the transmission / reception unit 30A of the wireless communication device 5A illustrated in FIG. Interleaving is performed in order to prevent deterioration in error rate of a specific subcarrier in a multipath environment and deterioration in error rate due to fading in a mobile environment.

  In addition, the same code | symbol is attached | subjected to the part same as FIG. 10, and the overlapping description is abbreviate | omitted.

  FIG. 14 is a flowchart for explaining an example of a signal transmission process of the wireless communication device 5B shown in FIG. The flowchart of the process in which the wireless communication device 5B according to this modification transmits a signal has a configuration in which the process by the interleave unit 120 is added to the process by the transmission / reception unit 30A among the plurality of processes in the flowchart shown in FIG. ing. Therefore, the same parts as those in FIG.

  After determining the number of OFDM symbols to be buffered (the number of OFDM symbols in one frame) in step S116, the control unit 31 in FIG. 13 determines the size of interleaving performed in the interleaving unit 120 in FIG. The determined interleave size (interleave length) is set in unit 120 (step S130).

  Here, the interleave size is, for example, the total number of bits transmitted in one frame, the total number of subcarriers determined in step S112, the modulation scheme determined in step S115, and the one frame determined in step S116. It is determined from each of the number of OFDM symbols. For example, if the number of OFDM symbols in one frame determined in step S116 is 10, the total number of subcarriers determined in step S112 is 48, and the modulation scheme determined in step S115 is QPSK, one subcarrier is used in QPSK modulation. Since 2 bits per information can be modulated, the interleave size is 10 × 48 × 2 = 960.

  After determining the scale of the second Fourier transform in step S117, the control unit 31 sets various parameters determined in the same manner as in FIG. 11 in each block of the transmission / reception unit 30B. Subsequently, the interleaving unit 120 in FIG. 13 performs buffering of the bit string input from the input terminal (step S131), and determines whether the specified number of bits input from the control unit 31 has been reached (step S131). S132). If the specified number of bits has not been reached, the No route is passed and buffering of the bit string is continued (step S131). If the specified number of bits is reached, the buffered bit sequence is interleaved by passing through the Yes route (step S131). S133). The bit string interleaved in step S133 is input to the subcarrier signal allocation unit 33, and the same processing as in step S118 and subsequent steps shown in FIG. 11 is performed. Each process from step S118 to step S50 is the same as the process described above.

  As described above, when the transmission bit string is interleaved, the error rate in the multipath environment and the error rate due to fading in the mobile environment are improved, and at the same time, the OFDM symbol is buffered. The delay does not occur as an additional delay that affects the processing speed of the transmission / reception signal. That is, it can be said that the amount of delay associated with buffering is not so large.

(Second modification of the second embodiment)
Next, an example in which processing for determining the scale of Fourier transform is included will be described.

  FIG. 15 is a process for determining the scale of the second Fourier transform in the signal transmission flowcharts shown in FIGS. 11 and 14 performed by the wireless communication device 5A (FIG. 10) and the wireless communication device 5B (FIG. 13) (step S117). It is a flowchart for demonstrating an example of this detailed process. 10 and 13 compares the minimum reception sensitivity of the radio communication system sharing the frequency with a predetermined threshold based on the table shown in FIG. 5 stored in the memory 32 ( Step S130).

  If the minimum receiving sensitivity is, for example, −80 dBm or more, the scale of the second Fourier transform is determined to be, for example, 1024 points (step S131). On the other hand, if the minimum reception sensitivity is −100 dBm or more and less than −80 dBm, the scale of the second Fourier transform is determined to be 2048 points, for example (step S132). Furthermore, if it is smaller than −100 dBm, the scale of the second Fourier transform is determined to be 4096 points, for example (step S133). Here, the lower the minimum reception sensitivity of the radio communication system sharing the frequency, the weaker the interference is. Therefore, by increasing the scale of the second Fourier transform, the frequency resolution is increased and the zero signal reproduction ( Since the null subcarrier can be reset to “0” with finer frequency accuracy at the time of step S124 in FIG. 14, sidelobe component leakage from the subcarrier to which the signal is assigned to the plurality of null subcarriers is prevented. It is possible to reduce interference to a frequency channel in use in a wireless communication system that is kept low and shares a frequency.

(Third embodiment)
FIG. 16 is a schematic block diagram of a wireless communication device 5C according to the third embodiment of the present invention. The wireless communication device 5C according to the present embodiment includes a transmission / reception unit 30C, and the transmission / reception unit 30C has a configuration in which a power amplifier distortion generation unit 140 is added to the transmission / reception unit 30B of the wireless communication device 5B illustrated in FIG. It has become. The power amplifier distortion generator 140 is a power amplifier (not shown) that amplifies a plurality of subcarriers based on a predetermined output backoff value for a plurality of time signals buffered in the buffering unit 100. Distortion is applied according to the input / output amplitude characteristics and input / output phase characteristics, and a plurality of time signals with distortion are input to the Fourier transform unit 101. The power amplifier distortion generating unit 140 can be realized by a CPU, ROM, RAM, IC, LSI, and the like. The same parts as those in FIG. 3 are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 17 is a flowchart for explaining an example of a signal transmission process of the wireless communication device 5C shown in FIG. 16, and distortion is generated by the power amplifier between step S122 and step S123 in the flowchart shown in FIG. A process (step S150) is added. Therefore, the same parts as those in FIG.

  In step S122 of FIG. 17, when the buffering unit 100 performs buffering for the specified number of OFDM symbols, the signal connected through the Yes route and buffered is output to the power amplifier distortion generation unit 140, and the power amplifier distortion generation unit 140 represents the amplitude of the signal input from the buffering unit 100 based on the input / output amplitude characteristics and input / output phase characteristics of the power amplifier used in the wireless communication device 5C and the back-off value with respect to the saturation output level. And distortion is generated in the phase (step S150). Here, the back-off value representing the difference between the maximum output level and the saturated output level is determined in advance by the power value of the transmission signal determined by the system specification. The signal distorted by the power amplifier is input to the Fourier transform unit 101 and subjected to Fourier transform (step S123). The processes after step S124 are the same as those in FIG.

  As described above, according to the wireless communication device 5C according to the present embodiment, zero reproduction is performed in consideration of the power amplifier, and the side lobe component of the subcarrier to which the signal is assigned is caused by the nonlinearity of the power amplifier. Since the power leaking to the null subcarrier can be kept low, interference with the frequency channel in use of the wireless communication system sharing the frequency can be kept low.

(Fourth embodiment)
FIG. 18 is a schematic block diagram of a wireless communication device 5D according to the fourth embodiment of the present invention. The wireless communication device 5D according to the present embodiment includes a filter unit 161, a carrier detection signal buffering unit 162, a carrier detection Fourier transform unit 163, a frequency channel power measurement unit 164, and a wireless communication device 5C illustrated in FIG. A carrier detection unit 160 including a carrier determination unit 165 is added.

  The filter unit 161 is a filter unit having band pass characteristics of a plurality of subcarriers used in the wireless communication system 1.

  The carrier detection signal buffering unit 162 is a second buffering unit that buffers the signal filtered by the filter unit 161 for a predetermined time.

  The carrier detection Fourier transform unit 163 is a second Fourier transform unit that performs a Fourier transform on the signal buffered in the carrier detection signal buffering unit 162.

  The frequency channel power measurement unit 164 measures the power for each subcarrier corresponding to each of a plurality of frequency channels used in the wireless communication system 2 for the signal Fourier-transformed by the carrier detection Fourier transform unit 163. Carrier power measuring means.

  The carrier determination unit 165 determines a frequency channel being used among a plurality of frequency channels used in the wireless communication system 2 based on the power measurement result in the frequency channel power measurement unit 164.

  Then, the subcarrier signal allocation unit 33 allocates a modulation subcarrier and a null subcarrier based on the frequency channel determined by the carrier determination unit 165. The carrier detection unit 160 is realized by a CPU, ROM, RAM, IC, LSI, and the like.

  When the wireless communication system 1 shares frequency with the six wireless communication systems B to G, the frequency channel power measurement unit 164 and the carrier determination unit 165 are used in the wireless communication systems B to G. Power measurement and frequency channel determination of a plurality of frequency channels.

  In addition, the same code | symbol is attached | subjected to the part same as FIG. 16, and the overlapping description is abbreviate | omitted.

  FIG. 19 is a diagram illustrating an example of a table held in the memory 32A of the wireless communication device 5D illustrated in FIG. 18, in which a threshold value for carrier detection is added to the table illustrated in FIG. Therefore, the same parts as those in FIG. The table shown in FIG. 19 is similar to FIG. 5 for the wireless communication systems B, R, C, D, E, F, G. In addition to the information shown in FIG. 5, a threshold value for carrier detection is stored. For example, when the radio communication system E is selected as the radio communication system in which the radio communication device 5D shares the frequency, power measurement for carrier detection is performed, and the measurement power in one frequency channel is −100 dBm or more. In this case, it is determined that there is a carrier (the frequency channel is used).

  FIG. 20 is a flowchart for explaining an example of the carrier detection process of the wireless communication device 5D shown in FIG. The control unit 31 in FIG. 18 uses the number of filter taps that allow the bandwidth of the multicarrier communication performed in the wireless communication system 1 determined in step S42 in FIG. 4 and step S112 in FIGS. 11, 14, and 17 to pass. And the coefficient are calculated and set in the filter unit 161 (step S170). After setting the number of taps and the coefficient in the filter unit 161, the time for buffering the input signal is set in the carrier detection signal buffering unit 162 (step S171). Subsequently, the scale of the Fourier transform performed on the buffered signal is set in the carrier detection Fourier transform unit 163 and the frequency channel power measurement unit 164 (step S172).

  After setting the scale of the Fourier transform, the wireless communication device 5D refers to the memory 32A and sets a power threshold value for determining the presence / absence of a carrier in the carrier determination unit 165 based on the system sharing the frequency ( Step S173). After setting the threshold for carrier detection, the filter unit 161 filters the received input signal (step S174), and outputs the filtered signal to the carrier detection signal buffering unit 162. The carrier detection signal buffering unit 162 buffers the signal input from the filter unit 161 (step S175), and determines whether or not the specified time set by the control unit 31 has elapsed (step S176). In step S176, if the specified time has not passed, the No route is passed and buffering is continued (step S175). If the specified time has passed, the Yes route is passed and the buffered signal is Fourier transformed for carrier detection. To the unit 163.

  The carrier detection Fourier transform unit 163 performs a Fourier transform of the scale set by the control unit 31 on the signal input from the carrier detection buffering unit 162 (step S177). The carrier detection Fourier transform unit 163 outputs the Fourier-transformed signal to the frequency channel power measurement unit 164, and the frequency channel power measurement unit 164 wirelessly shares the frequency of the signal input from the carrier detection Fourier transform unit 163. Power measurement is performed for each frequency channel of the communication system (step S178).

  The frequency channel power measurement unit 164 outputs the power measured for each frequency channel of the radio communication system sharing the frequency to the carrier determination unit 165, and the carrier determination unit 165 receives the frequency channel input from the frequency channel power measurement unit 164. Each measured power is compared with the threshold value set by the control unit 31, thereby determining carrier detection (step S179). The carrier determination unit 165 outputs the result of comparing the measured power and the threshold value for each frequency channel to the control unit 31 (step S180). After outputting the carrier determination result to the control unit 31 in step S180, it is determined whether or not to end communication (step S49). If communication is to be continued, the process from step S174 onward is repeated through the No route. For example, when a communication termination request is input from the user, the communication termination process is performed through the Yes route (step S50), and the communication is terminated.

  As described above, according to the wireless communication device 5D according to the present embodiment, by providing the carrier detection means, it is possible to recognize or grasp the frequency channel in use by the wireless communication system sharing the frequency. The radio communication system 1 can transmit and receive signals without interference using frequency channels that are not used by the shared radio communication system. At the same time, the radio communication system 1 can be used as a radio communication system that shares a frequency. It is possible to prevent interference.

(Fifth embodiment)
FIG. 21 is a schematic block diagram of a wireless communication device 5E according to the fifth embodiment of the present invention. The wireless communication device 5E according to the present embodiment has a configuration in which a timer 190 is added to the wireless communication device 5D illustrated in FIG.

  In the present embodiment, the control unit 31 executes a carrier determination process for determining a used frequency channel among a plurality of frequency channels used in the wireless communication system 2, and the carrier determination process. Based on the determination result, the wireless communication system 1 functions as a control unit that switches and controls a time for executing signal transmission / reception processing for transmitting and receiving signals. In addition, the same code | symbol is attached | subjected to the part same as FIG. 18, and the overlapping description is abbreviate | omitted. A memory denoted by reference numeral 32B will be described in a sixth embodiment to be described later.

  Thus, the carrier sense slot and the transmission / reception slot are repeated as described below.

  FIG. 22 is a flowchart for explaining an example of a signal transmission process of the wireless communication device 5E shown in FIG. The flowchart shown in FIG. 22 combines a flowchart showing an example of a process in which the wireless communication device 5C shown in FIG. 17 transmits a signal and a flowchart showing an example of a process in which the wireless communication device 5D shown in FIG. It is a thing. Accordingly, the same parts as those in FIGS. 17 and 20 are denoted by the same reference numerals, and redundant description is omitted.

  The control part 31 of FIG. 21 determines the radio | wireless communications system which shares a frequency (step 110). Subsequently, the number of subcarriers for multicarrier communication performed in the wireless communication system 1 corresponding to one frequency channel of the wireless communication system 2 sharing the frequency with the wireless communication system 1 is determined. The channel bandwidth is set to be the bandwidth of two or more subcarriers of the wireless communication system 1 (step S111).

  After determining the number of subcarriers for multicarrier communication performed in the radio communication system 1 corresponding to one frequency channel of the radio communication system 2 in which the radio communication system 1 shares the frequency in step S111, the control unit 31 in FIG. The total number of subcarriers (the signal bandwidth in the wireless communication system 1) of the multicarrier communication performed by the wireless communication system 1 is determined, but the wireless communication system 1 seems to share two or more frequency channels of the wireless communication system 2. Next, the total number of subcarriers is determined (step S112).

  In step S112, when the control unit 31 determines the total number of subcarriers for multicarrier communication, the scale of the inverse Fourier transform performed by the inverse Fourier transform unit 35 (the scale of the first Fourier transform) is determined (step S113). When determining the scale of the inverse Fourier transform, the controller 31 determines the length of the guard time based on the information described in the memory 32 (step S114). When determining the length of the guard time, the control unit 31 determines the modulation method (step S115). After determining the modulation method in step S115, the control unit 31 determines the number of OFDM symbols to be buffered by the buffering unit 100 in FIG. 21 (step S116).

  When the number of OFDM symbols to be buffered is determined in step S116, the size of interleaving performed by interleaving section 120 in FIG. 21 is determined (step S130). After the interleave size is determined, the scale of Fourier transform and inverse Fourier transform (scale of the second Fourier transform) performed by the Fourier transform unit 101 and the second inverse Fourier transform unit 103 in FIG. 21 is determined (step S117). .

  After determining the scale of the second Fourier transform, the number of filter taps and coefficients that pass the bandwidth of the multicarrier communication performed in the wireless communication system 1 are calculated and set in the filter unit 161 (step S170). After setting the number of taps and the coefficient in the filter unit 161, the time for buffering the input signal is set in the carrier detection signal buffering unit 162 (step S171). Subsequently, the scale of the Fourier transform performed on the buffered signal is set in the carrier detection Fourier transform unit 163 and the frequency channel power measurement unit 164 (step S172). After setting the scale of the Fourier transform, the memory 32 is referred to and a power threshold value for determining the presence / absence of a carrier based on the system sharing the frequency is set in the carrier determination unit 165 (step S173). After step S173, the control unit 31 refers to the timer 190 to determine whether it is the start time of the carrier sense slot (step S200).

  If it is not the start time of the carrier sense slot, it passes through the No route and waits until the start time is reached, and if it is the start time of the carrier sense slot, it passes the Yes route and outputs a start signal to the carrier detection unit 160, 161 filters the received input signal (step S174), and outputs the filtered signal to the carrier detection signal buffering unit 162. The carrier detection signal buffering unit 162 buffers the signal input from the filter unit 161 (step S175), and determines whether or not the specified time set by the control unit 31 has elapsed (step S176).

  If the specified time has not elapsed, the No route is passed and buffering is continued (step S175). If the specified time has passed, the Yes route is passed and the buffered signal is output to the carrier detecting Fourier transform unit 163. To do. The carrier detection Fourier transform unit 163 performs a Fourier transform of the scale set by the control unit 31 on the signal input from the carrier detection buffering unit 162 (step S177). The carrier detection Fourier transform unit 163 outputs the Fourier-transformed signal to the frequency channel power measurement unit 164, and the frequency channel power measurement unit 164 wirelessly shares the frequency of the signal input from the carrier detection Fourier transform unit 163. Power measurement is performed for each frequency channel of the communication system (step S178).

  The frequency channel power measurement unit 164 outputs the power measured for each frequency channel of the wireless communication system sharing the frequency to the carrier determination unit 165, and the carrier determination unit 165 receives each frequency channel input from the frequency channel power measurement unit 164. The measured power and the threshold set by the control unit 31 are compared, and thereby carrier detection is determined (step S179). The carrier determination unit 165 outputs the result of comparing the measured power and the threshold value for each frequency channel to the control unit 31 (step S180).

  Based on the carrier detection result for each frequency channel of the wireless communication system that shares the frequency input from the carrier determination unit 165, the control unit 31 sets the subcarrier to assign a signal to the subcarrier signal assignment unit 33 and the sub to be set to null. Outputs carrier information. The control unit 31 refers to the timer 190 and determines whether it is the start time of the transmission / reception slot (step S201).

  If it is not the start time of the transmission / reception slot, it passes through the No route and waits until the start time is reached. If it is the start time of the transmission / reception slot, it passes the Yes route and outputs a start signal to the transmission / reception unit 30C (FIG. 21). The unit 120 uses the start signal input from the control unit 31 as a trigger to buffer the bit string input from the input terminal (step S131), and determines whether or not the specified number of bits input from the control unit 31 has been reached. A determination is made (step S132).

  If the specified number of bits has not been reached, the No route is passed and buffering of the bit string is continued (step S131). If the specified number of bits is reached, the buffered bit sequence is interleaved by passing through the Yes route (step S131). S133). The bit sequence interleaved in step S133 is input to the subcarrier signal allocation unit 33, and the transmission bit sequence input from the input terminal is mapped to each subcarrier based on the modulation scheme input from the control unit 31, and Null without mapping transmission bit string to subcarrier corresponding to frequency channel determined to be used among frequency channels of radio communication system 2 sharing frequency based on information input from control unit 31 ("0") is set (step S118).

  The inverse Fourier transform of the scale input from the control unit 31 is performed by the inverse Fourier transform unit 34 on the signal to which the modulation signal and the null are assigned by the subcarrier signal assignment unit 33 (step S119). The guard time adding unit 35 adds a guard time to the inverse Fourier transformed signal (step S120), and the buffering unit 100 combines the buffered and serial signals (step S121).

  The buffering unit 100 determines whether or not buffering is performed for the specified number of OFDM symbols set by the control unit 31 (step S122). If the buffering unit 100 is not buffered for the specified number of OFDM symbols, the buffering unit 100 passes through the No route. The processes from step S118 to step S121 are repeated until buffering is performed for the prescribed number of OFDM symbols. In step S122, if buffering is performed for the prescribed number of OFDM symbols, the signal connected through the Yes route and buffered is output to power amplifier distortion generating section 140.

  The power amplifier distortion generating unit 140 outputs a signal input from the buffering unit 100 based on the input / output amplitude characteristics and the input / output phase characteristics of the power amplifier used in the wireless communication apparatus 5E and the backoff value for the saturated output. On the other hand, distortion is generated in the amplitude and phase (step S150). The signal distorted by the power amplifier is input to the Fourier transform unit 101 and subjected to Fourier transform (step S123). In step S123, the signal subjected to the Fourier transform by the Fourier transform unit 101 is input to the zero signal reproduction unit 102, and is set to the null subcarrier by the subcarrier signal allocation unit 33 (the same processing as step S118), and corresponds to the subcarrier. The value of the subcarrier is set to “0” again (step S124).

  Note that the subcarrier number set as the null subcarrier by the subcarrier signal allocation unit 33 is input from the control unit 31. In step S124, the null-reset signal is input to the second inverse Fourier transform unit 103, subjected to inverse Fourier transform of the scale input from the control unit 31 (step S125), and output from the output terminal. Is done. After the signal is output from the output terminal in step S125, it is determined whether or not to end the communication (step S49). If the communication is continued, the process after step S200 is repeated through the No route, for example, When a communication termination request is input from the user, the communication termination process is performed through the Yes route (step S50), and the communication is terminated.

  As described above, according to the wireless communication device 5E according to the present embodiment, since the carrier sense slot and the transmission / reception slot are configured repeatedly, determination of the usage status of the frequency channel of the wireless communication system sharing the frequency, By repeating transmission / reception of the signal of the wireless communication system 1 based on the determination result, even when the usage status of the frequency channel of the wireless communication system sharing the frequency changes from moment to moment, this is followed and the frequency used By performing multicarrier communication with the channel set to null, communication can be continued in the wireless communication system 1 without interfering with the frequency channel in use of the wireless communication system sharing the frequency.

(Sixth embodiment)
FIG. 23 is a diagram illustrating an example of a table held in the memory 32B of the wireless communication device 5E illustrated in FIG. The table in FIG. 23 is storage means for storing the minimum burst time or burst length of a signal transmitted continuously by the wireless communication system 2 (or wireless communication systems B to G). This table is obtained by adding the minimum burst time of signals to be continuously transmitted in the wireless communication systems B to G to the table shown in FIG. Based on the minimum burst time of the signal stored in the table, the control unit 31 determines the time for executing the carrier determination process and the time for executing the signal transmission / reception process as the radio communication system 2 or the radio communication system. It is determined according to the communication methods and types of B to G.

  The table shown in FIG. 23 is similar to FIG. 5 for the wireless communication systems B, R, C, D, E, F, G. In addition to the information shown in FIG. 19, a minimum burst time of a signal transmitted continuously in each wireless communication system is stored. For example, the radio communication system B transmits signals continuously for 10 ms, the radio communication system C 24 μs, and the radio communication system G continuously transmits signals.

  FIG. 24 is a flowchart for explaining an example of processing in which the wireless communication device 5E shown in FIG. 21 determines the slot configuration. The control unit 31 in FIG. 21 determines whether or not the wireless communication system B sharing the frequency determined according to the flowchart shown in FIG. 6 is the wireless communication system B (step S210).

  If the wireless communication system sharing the frequency is the wireless communication system B, the carrier sense time is determined to be 8 ms and the signal transmission time is determined to be 8 ms through the Yes route (step S211). This represents that the carrier sense time of 8 ms and the signal transmission time of 8 ms are repeated. If the wireless communication system sharing the frequency is not the wireless communication system B, it is determined whether the wireless communication system passing through the No route and sharing the frequency is the wireless communication system C (step S212).

  If the wireless communication system sharing the frequency is the wireless communication system C, it passes through the Yes route and determines that the carrier sense time is 20 us and the signal transmission time is 20 us (step S213). This represents that the 20-us carrier sense time and the 20-us signal transmission time are repeated. If the radio communication system sharing the frequency is not the radio communication system C, it is determined whether or not the radio communication system sharing the frequency is the radio communication system D (step S214).

  If the wireless communication system sharing the frequency is the wireless communication system D, the carrier sense time is determined to be 25 us and the signal transmission time is determined to be 25 us through the Yes route (step S215). This indicates that the 25-us carrier sense time and the 25-us signal transmission time are repeated. If the wireless communication system that shares the frequency is not the wireless communication system D, it is determined whether the wireless communication system that passes through the No route and shares the frequency is the wireless communication system E (step S216).

  If the radio communication system sharing the frequency is the radio communication system E, the Yes route is passed, and the carrier sense time is determined to be 5 ms and the signal transmission time is determined to be 5 ms (step S217). This represents that the 5 ms carrier sense time and the 5 ms signal transmission time are repeated. If the wireless communication system that shares the frequency is not the wireless communication system E, it is determined whether the wireless communication system that passes the No route and shares the frequency is the wireless communication system F (step S218).

  If the radio communication system sharing the frequency is the radio communication system F, the Yes route is passed, and the carrier sense time is determined to be 8 us and the signal transmission time is determined to be 8 us (step S219). This represents that the 8 us carrier sense time and the 8 us signal transmission time are repeated. If the radio communication system sharing the frequency is not the radio communication system F, the carrier communication time is 10 ms and the signal transmission time is determined to be 10 ms because the radio communication system G passes the No route and shares the frequency. (Step S220). This indicates that the carrier sense time of 10 ms and the signal transmission time of 10 ms are repeated.

  Thus, for each wireless communication system sharing a frequency, by selecting a time shorter than the minimum burst time in which the wireless communication system continuously transmits signals as the signal transmission time of the wireless communication system 1, When a certain frequency channel is used for a radio communication system sharing a frequency, it is possible to reliably detect a signal of the radio communication system sharing the frequency in the carrier sense time.

  In addition, according to the wireless communication apparatus according to the present embodiment, the slot configuration is different for each type of license system. Therefore, if the types of the wireless communication systems B to G as the first wireless communication system are different, the frame format and slot Since the formats (signal transmission patterns) are also different, it is possible to appropriately select the slot format of the second wireless communication system according to the signal transmission patterns of the wireless communication systems B to G.

(Seventh embodiment)
FIG. 25 is a diagram illustrating an example of a frame format representing the content of broadcast information transmitted by the wireless communication device 5 (or 5A to 5E) as a wireless base station. The broadcast information frame shown in FIG. 25 shows an example in which the wireless communication system 1 includes a total of three wireless communication apparatuses, one wireless base station and two wireless terminal stations. In the present embodiment, one of the three wireless communication devices 5 (5A to 5E) is represented as a wireless base station A, and the other two devices are represented as wireless terminal stations A1 and A2.

  The control unit 31 according to the present embodiment includes information on the time for executing the carrier determination process and the time for executing the signal transmission / reception process in a frame of broadcast information having a predetermined format transmitted in the wireless communication system 1. Describe.

  The broadcast information frame format 230 shown in FIG. 25 includes a system identifier 231, a slot time length 232, a carrier sense period length 233, a signal transmission / reception period length 234, the number of subcarriers 235 per frequency channel for a radio communication system sharing frequency, Total number of subcarriers 236, guard time length 237, number of buffering OFDM symbols 238, interleave length 239, second Fourier transform scale 240, broadcast information transmission period 241, control information slot number 242, transmission right 1 allocation terminal 243, transmission right It consists of 1 allocation slot number 244, transmission right 2 allocation terminal 245, transmission right 2 allocation slot number 246, transmission right 3 allocation terminal 247, and transmission right 3 allocation slot number 248.

  FIG. 26 is a diagram showing specific values of the frame format of the broadcast information shown in FIG. When the contents set by the broadcast information frame format 230 shown in FIG. 26 are listed, the system identifier 231 is “System A”, the slot time length 232 is “16 ms”, the carrier sense period length 233 is “8 ms”, and the signal transmission / reception period length. 234 is “8 ms”, frequency sharing radio communication system 1 subcarrier number 235 per frequency channel is “16”, total subcarrier number 236 is “128”, guard time length 237 is “32 samples”, buffering OFDM The number of symbols 238 is “2 OFDM symbols”, the interleave length 239 is “8 ms”, the second Fourier transform scale 240 is “1024”, the broadcast information transmission period 241 is “10 slots”, and the number of control information slots 242 is “2 slots”. The transmission right 1 allocation terminal 243 is “wireless base station "The transmission right 1 allocation slot number 244 is" 3 slots ", the transmission right 2 allocation terminal 245 is" wireless terminal station A1 ", the transmission right 2 allocation slot number 246 is" 2 slots ", and the transmission right 3 allocation terminal 247 is" The wireless terminal station A2 ”and the transmission right 3 allocation slot number 248 are“ 2 slots ”.

  FIG. 27 is a sequence diagram illustrating an example of a frame configuration of the wireless communication system 1 when the broadcast information illustrated in FIG. 26 is transmitted. The length of each slot in FIG. 26 and FIG. 27 is an example in the case where the wireless communication device 5 (or 5A to 5E) performs cognitive wireless communication with the wireless communication system 2, and the wireless communication device 2 stores the wireless data stored in the memory 32 in FIG. Based on the minimum burst length (10 ms) of the continuous transmission signal in the communication system 2, it is determined as follows.

  26, since the period length of the carrier sense (CS) period 261 is 8 ms and the period length of the signal transmission / reception period 262 is 8 ms, one slot length is 16 ms, and the transmission interval of the broadcast information is Since there are 10 slots, one frame length 260 is 160 ms. After the broadcast information is transmitted in slot 263, since the number of control information slots shown in FIG. 26 is 2, slots 264 and 265 become control information slots.

  The control information slot is, for example, a slot in which a connection request frame or the like is transmitted. The transmission right 1 shown in FIG. 26 is assigned to the radio base station A, and the number of slots to which the transmission right 1 is assigned is 3. Therefore, the radio base station A uses the data slots stored in the slots 266, 267, and 268. Transmits a signal.

  The transmission right 2 shown in FIG. 26 is assigned to the wireless terminal station A1, and the number of slots to which the transmission right 2 is assigned is 2. Therefore, the wireless terminal station A1 uses the data slots stored in the slots 269 and 270 to transmit signals. Send. The transmission right 3 shown in FIG. 26 is assigned to the wireless terminal station A2, and the number of slots to which the transmission right 3 is assigned is 2. Therefore, the wireless terminal station A2 uses the data slots stored in the slots 271 and 272 to transmit signals. Send.

  FIG. 28 is a diagram illustrating an example of a frequency bandwidth in which broadcast information is transmitted. 28, one subcarrier 280 of the wireless communication system 1, one frequency channel 281 of the wireless communication system in which the wireless communication system 1 shares a frequency, the full bandwidth 282 of multicarrier communication performed by the wireless communication system 1, and A bandwidth 283 in which broadcast information of the wireless communication system 1 is transmitted is shown. As shown in FIG. 28, broadcast information is always transmitted with a bandwidth corresponding to one frequency channel of a radio communication system that shares a frequency, and parameters such as the total number of subcarriers, guard time length, and number of OFDM symbols are wireless. A predetermined value is commonly used for the base station A and the wireless terminal stations A1 and A2.

  In this way, the radio base station transmits the broadcast information with the slot configuration and parameters for transmission and reception being transmitted, so that the radio terminal station that has received the broadcast information can communicate with the radio base station based on the slot configuration and the transmission / reception parameters. Wireless communication can be performed.

(Eighth embodiment)
FIG. 29 is a schematic block diagram of a wireless communication device 5F according to the eighth embodiment of the present invention. The wireless communication device 5F according to the eighth embodiment has a configuration in which a reception unit 290 is added to the wireless communication device 5E illustrated in FIG. The control unit 31 according to the present embodiment obtains information related to the time for executing the carrier determination process and the time for executing the signal transmission / reception process from the broadcast information described in the frame transmitted in the wireless communication system 1. In addition, the same code | symbol is attached | subjected to the part same as FIG. 21, and the overlapping description is abbreviate | omitted. The wireless communication device 5F according to the present embodiment can also use the memories 32A and 32B.

  FIG. 30 is a flowchart for explaining an example of processing from scanning of notification information to communication start of the wireless communication device 5F shown in FIG. 29 sets reception parameters such as a predetermined carrier frequency and the total number of subcarriers in reception unit 290 (step S300). Subsequently, the timer 190 is activated in the set frequency channel and waits for notification information to be received for a certain time (step S301). It is determined whether broadcast information is received on one frequency channel (step S302). If broadcast information is not received, it is determined whether a scan is performed for all frequency channels of all systems through the No route. (Step S303).

  In step S303, if scanning is not performed for all frequency channels of all systems, the route is changed through No route (step S304), and the processing from step S301 to step S303 is repeated. If scanning has been completed for all frequency channels of all systems, the Yes route is followed.

  On the other hand, when broadcast information is received in step S302, data transmission / reception parameters are extracted from the received broadcast information (step S305), and the extracted data transmission / reception parameters are set in the transmission / reception unit 30C (step S306).

  Subsequently, it is determined whether or not the broadcast information is a control information slot (step S307). If it is not a control information slot, it passes through the No route and waits until the control information slot start time is reached. On the other hand, when the start time of the control information slot is reached, a connection request frame or a registration request frame is transmitted to the radio base station A through the Yes route (step S308). After transmitting the connection request frame, it is determined whether or not a connection permission frame has been transmitted (step S309). If the connection permission frame is received, transmission / reception of data is started through the Yes route (step S310). On the other hand, when the connection permission frame is not received in step S308, the process from step S301 to step S308 is repeated through the No route.

  As described above, the carrier sense of the wireless communication system sharing the frequency and the transmission / reception of data of the wireless communication system A are performed in synchronization with the wireless base station A based on the slot configuration and the data transmission / reception parameters described in the broadcast information. And reliable communication.

(Ninth embodiment)
FIG. 31 is a diagram illustrating an example of the frequency arrangement of the frequency channels of the wireless communication system 2 and the wireless communication system 1.

  In the ninth embodiment, the modulation multilevel number of the modulation scheme used when the subcarrier signal allocation unit 33 allocates a transmission bit string to a subcarrier corresponding to a frequency channel not used in the radio communication system 2 is the radio communication system. 2 is lower as it is closer to the frequency channel used, and higher as it is farther from the frequency channel used by the wireless communication system 2.

  Reference numerals 320, 321, and 322 in FIG. 31 denote one frequency channel (or frequency channel band) of the wireless communication system in which the wireless communication system 1 shares the frequency, and the frequency channels 320 having these bandwidths, 322 is determined not to be used by the carrier sense of the wireless communication device 5, but the frequency channel 321 is determined to be determined to be used by the wireless communication system sharing the frequency by the carrier sense. Therefore, the wireless communication device 5 performs multicarrier communication using the frequency bands 320 and 322.

  323 and 324 in FIG. 31 indicate subcarriers of the wireless communication system 1 adjacent to the frequency channel used by the wireless communication system sharing the frequency, and interference from the frequency channel used by the wireless communication system sharing the frequency. Therefore, a modulation scheme different from that of the other subcarriers 325 and 326 is used.

  FIG. 32 is a flowchart illustrating an example of processing in which the control unit 31 determines the modulation schemes of the subcarriers 323 and 324 illustrated in FIG. The wireless communication device 5 measures the power for each frequency channel of the wireless communication system sharing the frequency in the carrier sense slot (step S330), and performs carrier detection determination similarly to the flowchart of FIG. 20 (step S179).

  As a result of the carrier detection determination, the wireless communication device 5 compares the power of the frequency channel determined to be in use with a threshold (step S331). For example, if it is −60 dBm or more, the subcarrier 323 shown in FIG. 324 is determined to be BPSK (step S332). On the other hand, if the power of the frequency channel determined to be in use is smaller than −60 dBm, the modulation scheme of subcarriers 323 and 324 shown in FIG. 31 is determined as QPSK (step S333).

  In the present embodiment, the wireless communication devices 5A to 5F operate in the same manner as the wireless communication device 5.

  As described above, according to the wireless communication devices 5 and 5A to 5F according to the present embodiment, since the modulation method is selected, the frequency channel is closer to the frequency channel used by the wireless communication system sharing the frequency. Since the side lobe component of the signal becomes interference, the total throughput characteristic can be improved by using a modulation method having high error tolerance.

  FIG. 33 is a diagram illustrating an example of a signal spectrum in which the wireless communication device 5 (FIG. 3) and the wireless communication device 5A (FIG. 10) transmit signals according to the flowcharts illustrated in FIGS. 4 and 11. A spectrum 340 in FIG. 33 is an example in a case where one frequency channel of a wireless communication system sharing a frequency corresponds to one subcarrier of multicarrier communication performed by the wireless communication system 1.

  On the other hand, the spectrum 341 in FIG. 33 is an example in which one frequency channel of the radio communication system sharing the frequency corresponds to four subcarriers of multicarrier communication performed by the radio communication system 1. When comparing the spectrum 340 and the spectrum 341 in FIG. 33, the spectrum 341 has 4-5 dB null subcarrier power reduced compared to the spectrum 340.

  The spectrum 342 shown in FIG. 33 is obtained by buffering 10 OFDM symbols obtained by adding a 16-point guard time to a 64-point inverse Fourier-transformed signal and performing a 1024-point Fourier transform according to the flowchart shown in FIG. 33 shows a spectrum when zero reproduction is performed, and reference numeral 343 in FIG. 33 shows a spectrum when zero reproduction is performed after Fourier transform of 8192 points. When the spectrum 341 and the spectrum 343 are compared, the spectrum 343 has 8 to 9 dB null subcarrier power reduced compared to the spectrum 341.

(Tenth embodiment)
FIG. 34 is a schematic block diagram of a wireless communication device 45A according to the tenth embodiment of the present invention. The wireless communication device 45A of this embodiment adds an oversampling unit 400 and a low-pass filter unit 401 between the buffering unit 100 and the Fourier transform unit 101 of the transmission / reception unit 30 of the wireless communication device 45A shown in FIG. It has become the composition. The oversampling unit 400 performs oversampling of the value set by the control unit 31 on the output of the buffering unit 100. The low-pass filter unit 401 performs digital processing such as ideal low-pass filter processing on the value output from the oversampling unit 400.

  FIG. 35 is a flowchart for explaining an example of a signal transmission process of the wireless communication device 45A shown in FIG. This adds an oversample number determination process (step S410) between step S116 and step S117 of the flowchart shown in FIG. 11, and oversample (step S411) and low-pass filter (step S412) between step S122 and step S123. Is added. When the number of OFDM symbols to be buffered is determined in step S116, the control unit 31 determines the number of oversamples for the buffered signal according to the rules described later (step S410). After determining the number of oversamples, the process of step S117 is performed. In step S122, the signal obtained by buffering and connecting a predetermined number of OFDM symbols by the buffering unit 100 is input to the oversampling unit 400. The oversampling unit 400 performs oversampling of the value set by the control unit 31 (step 411).

  The signal that is oversampled and output by the oversampling unit 400 is input to the low-pass filter unit 401, and low-pass filter processing is performed (step S412). The signal subjected to the low-pass filter processing is input to the Fourier transform unit 101 and subjected to Fourier transform (step S123). Thereafter, the same processing as in FIG. 11 is performed.

  By performing the above processing, the power leaked to the null subcarrier due to oversampling can be filtered and suppressed to a low level, so that interference with the frequency channel in use of the wireless system sharing the frequency can be prevented. It can be kept low.

  FIG. 36 is a flowchart for explaining an example of the process of determining the number of oversamples (step S410) and the scale of the second Fourier transform (step S117) in the signal transmission flow shown in FIG. 35 performed by the wireless communication device 45A. It is a flowchart of.

  Based on the table shown in FIG. 5 stored in the memory 32, the control unit 31 compares the minimum reception sensitivity of the wireless system sharing the frequency with a predetermined threshold value (step S130). If the minimum reception sensitivity is, for example, −80 dBm or more, the number of oversamples is determined to be four times (step S420), and the scale of the second Fourier transform is determined to be, for example, 4096 points (step S421). On the other hand, if the minimum reception sensitivity is −100 dBm or more and less than −80 dBm, the number of oversamples is determined to be 8 times (step S422), and the scale of the second Fourier transform is determined to be 8192 points, for example (step S423). If it is smaller than −100 dBm, the number of oversamples is determined to be 16 times (step S424), and the scale of the second Fourier transform is determined to be 16384 points (step S425).

  Here, the lower the minimum reception sensitivity of a radio system sharing the frequency, the weaker the interference is. Therefore, by increasing the number of oversamples and the scale of the second Fourier transform, the frequency resolution becomes higher and zero. Since the null subcarrier can be reset to “0” with finer frequency accuracy at the time of signal reproduction (step S124), sidelobe component leakage from the subcarrier to which the signal is assigned to the plurality of null subcarriers is prevented. It is possible to reduce the interference to the frequency channel in use of the wireless system that is kept low and shares the frequency.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In the above embodiment, the number of buffered OFDM symbols is 10. However, the number of OFDM symbols may be set to a desired value of 2 or more.

  In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

It is a figure which shows an example of a schematic structure of the radio | wireless communications system to which this invention is applied. It is a figure which shows the example of arrangement | positioning of the several frequency channel in the frequency band allocated to the 1st radio | wireless communications system. 1 is a schematic block diagram of a wireless communication apparatus according to a first embodiment of the present invention. It is a flowchart for demonstrating an example of the signal transmission process of the radio | wireless communication apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the table for selecting the radio | wireless communications system which shares a frequency from several 1st radio | wireless communications systems. In the flowchart of FIG. 4, it is a flowchart for demonstrating an example of the detailed process of step S40. In the flowchart of FIG. 4, it is a flowchart for demonstrating an example of the detailed process of step S41. In the flowchart of FIG. 4, it is a flowchart for demonstrating an example of the detailed process of step S42. In the flowchart of FIG. 4, it is another flowchart for demonstrating an example of the detailed process of step S42. It is a schematic block diagram of the radio | wireless communication apparatus which concerns on the 2nd Embodiment of this invention. It is a flowchart for demonstrating an example of the signal transmission process of the radio | wireless communication apparatus which concerns on the 2nd Embodiment of this invention. It is a figure for demonstrating the reproduction | regeneration process of the zero signal of the radio | wireless communication apparatus which concerns on the 2nd Embodiment of this invention. It is a schematic block diagram of the radio | wireless communication apparatus which concerns on the 1st modification of the 2nd Embodiment of this invention. It is a flowchart for demonstrating an example of the signal transmission process of the radio | wireless communication apparatus which concerns on the 1st modification of the 2nd Embodiment of this invention. It is a flowchart for demonstrating an example of the signal transmission process of the radio | wireless communication apparatus which concerns on the 2nd modification of the 2nd Embodiment of this invention. It is a schematic block diagram of the radio | wireless communication apparatus which concerns on the 3rd Embodiment of this invention. It is a flowchart for demonstrating an example of the signal transmission process of the radio | wireless communication apparatus which concerns on the 3rd Embodiment of this invention. It is a schematic block diagram of the radio | wireless communication apparatus which concerns on the 4th Embodiment of this invention. It is a figure which shows an example of the table for performing the subcarrier electric power measurement and carrier determination of the radio | wireless communication apparatus which concerns on the 4th Embodiment of this invention. It is a flowchart for demonstrating an example of the carrier detection process of the radio | wireless communication apparatus which concerns on the 4th Embodiment of this invention. It is a schematic block diagram of the radio | wireless communication apparatus which concerns on the 5th Embodiment of this invention. It is a flowchart for demonstrating an example of the signal transmission process of the radio | wireless communication apparatus which concerns on the 5th Embodiment of this invention. It is a figure which shows the example of data of the minimum burst time of the signal which the memory | storage means of the radio | wireless communication apparatus which concerns on the 6th Embodiment of this invention hold | maintains. It is a flowchart for demonstrating an example of the slot structure determination process of the radio | wireless communication apparatus which concerns on the 6th Embodiment of this invention. It is a figure which shows an example of the frame format showing the content of the alerting | reporting information which the radio | wireless communication apparatus which concerns on the 7th Embodiment of this invention transmits. It is a figure which shows the specific value of the format of the alerting | reporting information frame of FIG. FIG. 27 is a sequence diagram illustrating an example of a frame configuration of a wireless communication system when the broadcast information of FIG. 26 is transmitted. It is a figure which shows an example of the frequency bandwidth in which alerting | reporting information is transmitted. It is a schematic block diagram of the radio | wireless communication apparatus which concerns on the 8th Embodiment of this invention. It is a flowchart for demonstrating an example of the process from the scan of the alerting | reporting information to communication start in the radio | wireless communication apparatus which concerns on the 8th Embodiment of this invention. It is a figure which shows an example of frequency arrangement | positioning of each frequency channel of a 1st radio | wireless communications system and a 2nd radio | wireless communications system. It is a flowchart for demonstrating the determination method of the modulation system with respect to several subcarriers in the radio | wireless communication apparatus which concerns on the 9th Embodiment of this invention. It is a figure which shows an example of the signal spectrum which the radio | wireless communication apparatus of this invention transmits and outputs. It is a schematic block diagram of the radio | wireless communication apparatus which concerns on the 10th Embodiment of this invention. It is a flowchart for demonstrating an example of the signal transmission process of the radio | wireless communication apparatus which concerns on the 10th Embodiment of this invention. It is a flowchart for demonstrating an example of the signal transmission process of the radio | wireless communication apparatus which concerns on the 10th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Wireless communication system (2nd wireless communication system), 2-4 ... Wireless communication system (1st wireless communication system), 5, 5A, 5B, 5C, 5D, 5E, 5F, 6-9 ... Wireless communication Device, 10-17 ... frequency band, 18-22 ... frequency channel, 30, 30A, 30B, 30C ... transmission / reception unit, 31 ... control unit (subcarrier allocation control unit, control unit), 32, 32A, 32B ... memory ( Storage means), 33... Subcarrier signal allocation unit (subcarrier signal allocation means), 34... Inverse Fourier transform unit (inverse Fourier transform unit, first inverse Fourier transform unit), 35... Guard time addition unit (guard time addition) Means), 100... Buffering section (buffering means), 101... Fourier transform section (Fourier transform means), 102... Zero signal reproducing section (zero signal reproducing means) , 103 ... second inverse Fourier transform unit (second inverse Fourier transform unit), 120 ... interleave unit, 140 ... power amplifier distortion generation unit (power amplifier distortion generation unit), 160 ... carrier detection unit, 161 ... filter unit ( Filter means), 162 ... Carrier detection signal buffering section (second buffering means), 163 ... Carrier detection Fourier transform section (second Fourier transform means), 164 ... Frequency channel power measurement section (subcarrier power measurement) Means), 165... Carrier judgment unit (carrier judgment means), 190... Timer, 230... Frame format, 231... System identifier, 232 ... Slot time length, 233 ... Carrier sense period length, 234. Number of subcarriers per frequency channel, 236 ... total number of subcarriers 237 ... guard time length, 238 ... number of buffered OFDM symbols, 239 ... interleave length, 240 ... second Fourier transform scale, 241 ... broadcast information transmission cycle, 242 ... number of control information slots, 243 ... transmission right 1 allocation terminal, 244 ... number of transmission right 1 assigned slots, 245 ... number of transmission right 2 assigned terminals, 246 ... number of transmission right 2 assigned slots, 247 ... number of transmission right 3 assigned terminals, 248 ... number of transmission right 3 assigned slots, 260 ... 1 frame length, 261 ... Carrier sense period, 262 ... signal transmission / reception period, 263 to 272 ... slot, 280 ... subcarrier, 281 ... frequency channel, 282 ... full bandwidth, 283 ... bandwidth, 290 ... receiver, 320 to 322 ... frequency channel, 323 ~ 326 ... subcarrier, 340-343 ... spectrum.

Claims (11)

A wireless communication device in a second wireless communication system that shares a frequency with a first wireless communication system assigned a predetermined frequency band and performs wireless communication using a plurality of subcarriers,
The bandwidth of the subcarrier is determined so that the bandwidth of one frequency channel used in the first wireless communication system is equal to the bandwidth of two or more subcarriers of the plurality of subcarriers. Subcarrier allocation control means;
Each of the two or more subcarriers corresponding to the frequency channel being used by the first wireless communication system is set to null, and corresponds to a frequency channel not being used by the first wireless communication system. Subcarrier signal allocation means for allocating modulation signals to the two or more subcarriers;
Inverse Fourier transform means for performing an inverse Fourier transform on each of the null subcarrier and the modulated subcarrier output from the subcarrier signal assignment means, and outputting a time signal;
Guard time adding means for adding a guard time to the time signal;
A wireless communication apparatus comprising: A wireless communication device in a second wireless communication system that shares a frequency with a first wireless communication system assigned a predetermined frequency band and performs wireless communication using a plurality of subcarriers,
A null is set for a subcarrier corresponding to a frequency channel used by the first radio communication system among the plurality of subcarriers, and a frequency channel not used by the first radio communication system is set. Subcarrier signal allocation means for allocating a modulation signal to any one of the corresponding subcarriers;
First inverse Fourier transform means for performing inverse Fourier transform on each of the null subcarrier and the modulated subcarrier output from the subcarrier signal assigning means and outputting a plurality of time signals composed of a plurality of symbols; ,
Guard time adding means for adding a guard time to each of the plurality of time signals;
Buffering means for buffering the plurality of time signals to which the guard time is added;
Fourier transform means for performing Fourier transform on a plurality of time signals buffered in the buffering means, each having a scale larger than the scale of the first inverse Fourier transform;
Zero signal reproduction means for reproducing a zero signal by replacing a subcarrier signal corresponding to the null subcarrier among a plurality of subcarrier signals Fourier-transformed by the Fourier transform means with zero;
A second inverse Fourier transform means for performing an inverse Fourier transform of the same scale as the scale of the Fourier transform by the Fourier transform means on the subcarrier signal including the subcarrier signal replaced with zero by the zero signal reproducing means;
A wireless communication apparatus comprising:   The distortion according to the input / output amplitude characteristics and input / output phase characteristics of a power amplifier that amplifies the plurality of subcarriers based on a desired backoff value with respect to the plurality of time signals buffered by the buffering means. 3. The wireless communication apparatus according to claim 2, further comprising power amplifier distortion generating means for inputting the plurality of time signals given and distorted to the Fourier transform means. Filter means having bandpass characteristics of a plurality of subcarriers used in the second wireless communication system;
Second buffering means for buffering the signal filtered by the filter means for a predetermined time;
Second Fourier transforming means for performing a Fourier transform on the signal buffered in the second buffering means;
Subcarrier power measuring means for measuring power for each subcarrier corresponding to each of a plurality of frequency channels used in the first wireless communication system with respect to the signal Fourier-transformed by the second Fourier transform means; ,
Carrier determination means for determining a used frequency channel among a plurality of frequency channels used in the first wireless communication system based on a power measurement result in the subcarrier power measurement means;
The radio communication apparatus according to claim 1 or 2, wherein the subcarrier signal allocating unit allocates the modulation subcarrier and the null subcarrier based on the frequency channel determined by the carrier determining unit.   Based on a time for performing carrier determination processing for determining a frequency channel being used among a plurality of frequency channels used in the first wireless communication system, and a determination result of the carrier determination processing 5. The wireless communication according to claim 1, further comprising a control unit that switches and controls a time for executing a signal transmission / reception process for transmitting / receiving a signal in the two wireless communication systems. apparatus. Storage means for storing a minimum burst time of a signal continuously transmitted by the first wireless communication system;
Based on the minimum burst time of the signal stored in the storage means, the control means sets the time for executing the carrier determination process and the time for executing the signal transmission / reception process as the first wireless communication. 6. The wireless communication apparatus according to claim 5, wherein the wireless communication apparatus is determined according to a communication method of the system.   The control means describes information relating to a time for executing the carrier determination process and a time for executing the signal transmission / reception process in a broadcast information frame having a predetermined format transmitted in the second wireless communication system. The wireless communication apparatus according to claim 5 or 6.   The control means obtains information related to a time for executing the carrier determination process and a time for executing the signal transmission / reception process from broadcast information having a predetermined format transmitted in the second wireless communication system. The wireless communication device according to any one of claims 5 to 7.   The modulation level of the modulation scheme used when the subcarrier signal allocation means allocates a transmission bit string to a subcarrier corresponding to a frequency channel that is not used in the first radio communication system is determined by the first radio communication system. The radio communication apparatus according to claim 1, wherein the radio communication apparatus is set to be lower as it is closer to a frequency channel to be used and higher as it is farther from a frequency channel used by the first radio communication system. A wireless communication method for a wireless communication apparatus in a second wireless communication system that shares a frequency with a first wireless communication system to which a predetermined frequency band is assigned and performs wireless communication using a plurality of subcarriers. And
The bandwidth of the subcarrier is determined so that the bandwidth of one frequency channel used in the first wireless communication system is equal to the bandwidth of two or more subcarriers of the plurality of subcarriers. ,
Each of the two or more subcarriers corresponding to the frequency channel being used by the first wireless communication system is set to null,
Assigning modulation signals to the two or more subcarriers corresponding to frequency channels not used by the first wireless communication system;
Perform inverse Fourier transform on the null subcarrier set to null and the modulated subcarrier assigned the modulation signal,
A radio communication method characterized by adding a guard time to the time signal subjected to the inverse Fourier transform means. A wireless communication method for a wireless communication apparatus in a second wireless communication system that shares a frequency with a first wireless communication system to which a predetermined frequency band is assigned and performs wireless communication using a plurality of subcarriers. And
A null is set for a subcarrier corresponding to a frequency channel used by the first wireless communication system among the plurality of subcarriers,
Assigning modulation signals to any of the subcarriers corresponding to frequency channels not used by the first wireless communication system;
Performing a first inverse Fourier transform on each of the null subcarriers set to null and the modulated subcarriers to which the modulation signal is assigned;
A guard time is added to each of the plurality of time signals subjected to the first inverse Fourier transform,
Buffering the plurality of time signals to which the guard time is added to a buffer;
Performing a Fourier transform on a plurality of time signals buffered in the buffer, each of which is larger than the scale of the first inverse Fourier transform,
Reproducing a zero signal by substituting zero for a subcarrier corresponding to the null subcarrier among a plurality of subcarrier signals subjected to Fourier transform,
A wireless communication method, wherein a second inverse Fourier transform having the same scale as the Fourier transform is performed on a subcarrier signal including a subcarrier signal replaced with zero.

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