JP5953523B2 - Wireless communication apparatus and wireless communication method - Google Patents

Description

  The present invention relates to a wireless communication apparatus that performs communication using an empty frequency band.

  With the rapid spread of wireless LAN (wireless local area network) and wireless PAN (wireless personal area network), wireless demand in ISM (industrial, scientific and medical) bands such as 2.4 GHz and 5 GHz is increasing. Yes. Therefore, effective use of limited radio resources will become more important in the future. However, in the ISM band, a plurality of radio communication systems are operated in an autonomous and distributed manner, and in an environment where these share the same frequency band, Decrease in utilization efficiency of radio resources due to interference and deterioration of fairness between systems become problems.

  Here, conventionally, a concept of dynamic spectrum access (DSA) in which fragmented free frequency bands are integrated and used as one radio channel in the ISM band or the like has been proposed (for example, Non-Patent Document 1). reference).

  As a spectrum control method suitable for the DSA, a spectrum division single carrier modulation method has been proposed in which a spectrum of single carrier modulation is divided into a plurality of bands by a bandpass filter, and each frequency is converted and transmitted (for example, Patent Document 1, Non-Patent Documents 2, 3, and 4).

  The aim of such a single carrier modulation DSA system is to bundle unused radio resources fragmented in the frequency domain. Therefore, as a DSA system signal transmission method, unused radio resources scattered in the frequency domain can be integrated, and spectrum division single carrier suitable for coexistence with other wireless communication systems that operate asynchronously and autonomously and distributedly Transmission schemes have been proposed.

  Conventionally, a method has been proposed in which a free frequency band that exists spatially using an array antenna in a wireless LAN is used for communication (for example, Non-Patent Document 5).

JP 2010-232857 A

Taro Maruma, Hitoshi Yano, Seiji Tsukamoto, Masazumi Ueha, “Proposal of Dynamic Spectrum Access System for Highly Efficient Frequency Sharing in ISM Band”, IEICE Technical Report, vol. 108, no. 446, SR2008-97 , pp.53-57, March 2009 Hitoshi Yano, Hideyoshi Tsuji, Yasuo Suzuki, Seiji Tsukamoto, Makoto Taro Maru, Masazumi Ueha, “Examination of Physical Channel Configuration of Dynamic Spectrum Access System for Highly Efficient Frequency Sharing in ISM Band”, IEICE Technical Report, SR2008- 98, pp. 59-64, March 2009 Hitoshi Yano, Hiroaki Oshima, Masahiro Uno, Kiyoshi Kobayashi, “Synchronization and Demodulation of ISM Band DSA System Using Spectrum Division Single Carrier Transmission”, IEICE Technical Report, vol. 111, no. 417, SR2011-79, pp .9-19, January 2012 Yano Hitoshi, Oshima Hiroshi, Tsukamoto Seiji, Miyasaka Yasuhiro, Sato Miki, Nakamoto Shigehiro, Kitazawa Shoichi, Oka Tomohiro, Aikawa Kaoru, Uno Masahiro, “Research and Development of DSA System for Effective Use of ISM Band Frequency Resources , IEICE Technical Report, vol. 111, no. 452, SR2011-79, pp.65-72, March 2012 M. Takai, J. Martin, A. Ren, and R. Bagrodia, ”Directional Virtual Carrier Sensing for Directional Antennas in Mobile Ad Hoc Networks,” in Proc. Of the 3rd ACM international symposium on Mobile ad hoc networking and computing, pp 183-193, ACM Press, 2002.

  However, in such a method using an array antenna in a wireless LAN, a vacant frequency that exists in a fragmentary manner on the frequency axis cannot be used, so that a sufficient frequency cannot be effectively used.

  FIG. 12 is a conceptual diagram for explaining a method of using an array antenna in such a conventional wireless LAN.

  FIG. 12A is a diagram for explaining the concept of frequency band allocation, and FIG. 12B is a diagram for explaining a radiation pattern by an array antenna.

  FIG. 12B shows a state in which the base station forms directivity patterns in three directions (#a direction, #b direction, and #c direction) using three array antennas.

  First, as shown to Fig.12 (a), a base station senses the use frequency band of another system about a #a direction, #b direction, and #c direction, respectively.

  When the base station intends to use the frequency band of communication data as shown in FIG. 12 (a), communication is possible because there is a vacancy in the #b direction, but for the #a direction and the #c direction. Communication is not possible because there is no available bandwidth.

  On the other hand, in a communication apparatus using the spectrum division single carrier modulation method in the conventional DSA, the use of such a spatial vacant frequency band has not been studied.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a wireless communication apparatus or a wireless communication method that can efficiently use an empty frequency band that exists spatially and fragmentally on the frequency axis. And

According to one aspect of the present invention, a wireless communication apparatus that performs communication using an empty frequency band, comprising a signal conversion means for converting a data signal into a signal for transmission by a spectrum division single carrier modulation method , In the spectrum division single carrier modulation system, a plurality of data channels respectively corresponding to a plurality of predetermined frequency bands for use in data communication are defined in advance, and an array antenna including at least two or more antennas, Amplitude phase control means for controlling the amplitude and phase of signals transmitted to and received from each antenna, and the signal strength received while controlling the radiation pattern of the array antenna by controlling the amplitude phase for each antenna by the amplitude phase control means measuring means for measuring, dividing a frequency band used for data transmission Te, a frequency converting means for converting the frequency band of the data channel corresponding to the idle frequency band of the data channel, based on the measurement result of the measuring means, in the frequency band used for data transmission, by another device Determine unused vacant frequency bands and radiation patterns corresponding to the vacant frequency bands, calculate amplitude phases corresponding to the radiation patterns used in each of the vacant frequency bands, and control the amplitude phase control means for communication. further comprising a control means for performing control means, the reception intensity by the measurement of the measuring means is a lower judged data channel, the data channel more data channels are to unused consecutive group preferentially respect of, that perform allocation to idle frequency band of the divided frequency bands.

  Preferably, the amplitude phase control means performs the multiple connection in the cell by time division multiplexing, so that for each time division multiplexing slot, the space in which another device is communicating with respect to the directivity intensity in the direction of the communication destination. The directivity of the array antenna is controlled so that the directivity intensity with respect to the direction of the region becomes weak.

Preferably, when there is a first plurality of unused N (N: natural number) groups of unused data channels , the control means selects a free frequency band from a group having a low received signal strength for the data channels in the group. When the allocation to the first plurality of groups is completed and the bandwidth required for transmission cannot be secured, the group of consecutive unused data channels while decrementing the value of N As for the second plurality of groups detected as: the frequency band division number used for data transmission is the processing for executing the allocation to the free frequency band from the group having the low received signal strength for the data channel in the group. Repeat until the maximum number of divisions is reached.

  Preferably, the measurement means measures the signal intensity by performing sequential sensing while equally dividing the spatial axis direction of the array antenna and switching the beam direction to each direction.

  Preferably, the measurement unit performs control so that the directivity of the array antenna is individually directed in a plurality of different directions, and measures the signal intensity in parallel in the plurality of directions.

According to another aspect of the present invention, there is provided a communication method for performing communication using a vacant frequency band by a spectrum division single carrier modulation method, and in the spectrum division single carrier modulation method, a plurality of predetermined values for use in data communication are provided. A plurality of data channels corresponding to each frequency band of the data channel are defined in advance, and the transmitter divides the frequency band used for data transmission into the frequency band of the data channel corresponding to the free frequency band among the data channels. send conversion to, transmitter, it controls the amplitude and phase of the signal received by each antenna of the array antenna, comprising the steps of: measuring a received signal strength while controlling the radiation pattern of the array antenna, a transmitter However, other devices in the frequency band used for data transmission based on the signal strength measurement results. Depending comprising: a data channel reception strength is determined to be lower by the measurement result of the signal strength for determining the radiation pattern respectively corresponding to the idle frequency band and the vacant frequency bands unused, more data Preferentially assigning the divided frequency bands to free frequency bands for a group of data channels whose channels are continuously unused, and the transmitter uses each of the free frequency bands A control step for performing communication by calculating an amplitude phase corresponding to the radiation pattern and controlling the amplitude and phase of a signal transmitted from each antenna of the array antenna.

  According to the present invention, the spatial frequency is measured by measuring the vacant frequency band that exists spatially and in pieces on the frequency axis, and controls the radiation pattern for each frequency band used for communication during data communication. It is possible to efficiently use vacant frequencies that are fragmented on the axis.

It is a block diagram which shows the structure of the radio | wireless transmitter 1000 in the radio | wireless communications system of embodiment. It is a conceptual diagram which shows the concept of a space axis spectrum sensing method. It is a conceptual diagram for demonstrating the example of the method of the beam control at the time of performing space axis spectrum sensing. It is a conceptual diagram which shows the example of the frequency channel structure of the system of this Embodiment operate | used in a 2.4 GHz ISM band. It is a figure which shows the time frame structure of the radio | wireless communications system of this Embodiment. It is a figure which shows the concept of shaping the modulation waveform before spectrum division. It is a figure which shows assignment | assignment of the division | segmentation of the frequency band in case an antenna does not have directivity. In this Embodiment, it is a figure explaining the structure in the case of performing the space division multiple connection using antenna directivity. 10 is a first flowchart illustrating a procedure in which wireless transmission apparatus 1000 performs data channel allocation based on the result of spatial spectrum sensing. 10 is a second flowchart illustrating a procedure in which wireless transmission apparatus 1000 performs data channel assignment based on the result of spatial spectrum sensing. It is a figure which shows the example of a structure of the receiver in a radio | wireless communications system. It is a conceptual diagram for demonstrating the method of using an array antenna in the conventional wireless LAN.

  Hereinafter, a radio communication system according to an embodiment of the present invention will be described with reference to the drawings. In the following embodiments, components and processing steps given the same reference numerals are the same or equivalent, and the description thereof will not be repeated unless necessary.

  FIG. 1 is a block diagram illustrating a configuration of a wireless transmission device 1000 in the wireless communication system of the embodiment.

  Note that the configuration of the wireless transmission device 1000 as shown in FIG. 1 can be adopted in either a base station or a mobile terminal.

  In FIG. 1, a configuration for transmitting a control channel signal, which will be described later, is not shown.

  Referring to FIG. 1, radio transmission apparatus 1000 performs signal processing for transmission on a digital signal given from input node 10 and S / P (serial / parallel) conversion unit 14. A Fourier transform unit 16, a spectrum mapping unit 20, and band pass filters (BPFs) 30-1 for dividing a signal to be transmitted into N predetermined band signals as will be described later. 30-N, frequency conversion units 40-1 to 40-N for converting the frequency band signals divided by the control of the control unit 102 into signals of a designated frequency band, and the amplitude phase controller 90 Corresponding to weighting factor multipliers 50-1 to 50-N that perform phase amplitude conversion for imparting directivity to the transmission signal by control, and M antennas 100-1 to 100-M, respectively. Provided, and up-converters 60-1 to 60-M for up-converting signals from the weight coefficient multipliers 50-1 to 50-N.

  The modulation unit 12 receives communication data that is a digital signal and digitally modulates the communication data. For the purpose of improving PAPR (Peak to Average Power Ratio) characteristics, the modulation waveform before spectrum division may be shaped by a roll-off filter (for example, refer to the following document). Wanna)

Literature: Yasuo Suzuki, Hitoshi Yano, Masazumi Ueha, “Shaping effect of spectrum-divided single carrier transmission”, Society Conference of IEICE, B-5-137, p. 491, September 2010 The S / P converter 14 converts the digitally modulated communication data into a plurality of signals arranged in parallel. When a roll-off filter is used at the time of digital modulation, the output signal near the IFFT frame boundary is distorted, so that the S / P conversion unit 14 and the P / S conversion unit 64 perform overlapping S / P conversion and duplication. P / S conversion may be performed.

  The Fourier transform unit 16 receives signals in a plurality of parallel arrays after S / P conversion, and converts the signals in the time domain into signals in the frequency domain by performing fast Fourier transform on these signals in parallel.

  The spectrum mapping unit 20 receives the signal after the fast Fourier transform, and performs spectrum mapping on the signal.

  Specifically, the spectrum mapping unit 20 divides the signal after the fast Fourier transform into N signals for the N BPFs 30-1 to 30-N and outputs the divided signals. The spectrum mapping unit 20 divides a plurality of frequency components included in a plurality of divided transmission spectrum blocks, which are parallel array signals after the fast Fourier transform, into a plurality of frequency bands set by the control unit 102. And a plurality of frequency components included in the plurality of divided transmission spectrum blocks may be divided into a plurality of frequency bands using the mapping matrix.

  The frequency conversion units 40-1 to 40-N also perform phase correction because the signal phase after frequency conversion becomes discontinuous when performing overlapping S / P conversion during S / P conversion ( (See above document). N is the number of sub-spectrums used in communication, and is an integer of 1 or more. When communication is performed using a plurality of sub-spectrums, N is 2 or more.

  Weighting factor multiplication unit 50-1 includes multipliers 52-11 to 52-1M for multiplying the signal from frequency conversion unit 40-1 by the weighting factor provided from amplitude phase control unit 90. The other weight coefficient multiplication units 50-2 to 50-N have the same configuration.

  Each of the up-converters 60-1 to 60-M converts the signal from the inverse Fourier transform unit 62, the P / S (parallel / serial) conversion unit 64, and the P / S conversion unit 64 into an analog signal and transmits it. A frequency converter 66 for up-conversion to a frequency and a power amplifier 68 are provided.

  The inverse Fourier transform unit 62 performs inverse fast Fourier transform on the signal after the spectrum mapping, and returns it to the time domain signal. The P / S converter 64 receives the signal after the inverse fast Fourier transform, and converts the parallel array signal into a serial array. As described above, the P / S converter 64 may perform overlapping P / S conversion.

  The frequency conversion unit 66 receives a digital signal in a serial arrangement after P / S conversion, converts the digital signal into an analog signal, and uses the locally oscillated signal for frequency conversion to generate an equivalent baseband transmission signal. Is converted to a transmission frequency band. The power amplification unit 68 amplifies the transmission signal frequency-converted by the frequency conversion unit 66 to a desired power. The transmission signal is transmitted via the antennas 100-1 to 100-M. Therefore, at the time of transmission, antennas 100-1 to 100-M function as array antennas whose transmission directivities can be controlled.

  The wireless transmission device 1000 further generates a reception directivity of the antennas 100-1 to 100-M from the amplitude / phase control unit 90 in order to perform “spatial axis spectrum sensing” as described later. A weighting factor multiplication unit 70 for multiplying the received signal by the weighting factor and a detector 80 for detecting the received signal level from the direction in which the reception directivity is suitable are included. The amplitude / phase controller 90 adjusts a weighting factor by which the transmission signal is multiplied in accordance with the control signal received via the detector 80.

  Further, the control unit 102 controls the spectrum mapping unit 20 and the frequency conversion units 40-1 to 40-N according to the detection result from the detector 80, as will be described later.

Note that the configuration for transmission by the wireless transmission device 1000 may be realized by hardware, or a part that can be realized by software may be realized by software such as a driver that drives the transmission device.
(Spatial axis spectrum sensing method)
Here, an outline of a three-dimensional spectrum sensing method in which a space axis is added to a time / frequency axis will be briefly described.

  FIG. 2 is a conceptual diagram showing the concept of the spatial axis spectrum sensing method.

  Referring to FIG. 2, in spatial axis spectrum sensing, radio transmission apparatus 1000, for example, a base station, forms a beam in a desired direction by using an array antenna, and an existing RAN (Radio Access Network) from the beam direction is formed. A signal is detected, and the presence or absence of a signal is determined by selecting a space by scanning the beam.

  As shown in FIG. 1, it is assumed that wireless transmission apparatus 1000 is configured with an M-element array antenna having a digital beam forming (DBF) function.

  At this time, the received signal x [n] is expressed by the following equation, ignoring thermal noise.

Here, w = [w ₁ ,..., W _M ] ^T represents a weight coefficient vector (weight vector), and s [n] = [s ₁ [n], ..., s _M [n]] ^T Represents an input vector of the received signal of the existing RAN, T represents transposition, and H represents complex conjugate transposition. N is a time sample.

  Using the above description, the received signal of a receiver equipped with an array antenna can be modeled as follows depending on the presence or absence of an existing RAN signal.

However, n [n] represents a thermal noise vector. Here, the subscript i represents a sampling point in the spatial axis direction.

The power spectrum Pi [k] obtained from the output signal x _i [n] of the array antenna can be modeled as follows. Note that F represents the Fourier transform, and k is the order of the frequency with the frequency sample interval as a unit.

As is clear from these equations, signal detection can be performed by applying a spectrum sensing method such as energy detection to the output signal of the array antenna.

  FIG. 3 is a conceptual diagram for explaining an example of a beam control method when performing spatial axis spectrum sensing.

  As shown in FIG. 3, the space axis direction is equally divided into Nspaces, and spectrum sensing is executed in the following procedure in the i-th observation space region.

i) Control the weight so that the beam is formed in the direction of observation space area number i. ii) Receive an existing RAN signal in the observation direction iii) Spectrum estimation (periodogram)
iv) Detection of received signal level of existing RAN in observation space area number i (threshold judgment)
As one power detection method, the above steps i) to iv) can be sequentially performed while switching the beam direction, that is, changing the observation space region number i.

  Alternatively, the control unit 102 can control the weight coefficient multiplication unit 70 so that the directivity of the array antenna is individually directed to a plurality of different directions, and can simultaneously detect power in a plurality of directions. is there.

  As described above, an empty space area that is not used by another device (system) in the space can be specified.

  FIG. 4 is a conceptual diagram showing an example of the frequency channel configuration of the system according to the present embodiment operated in the 2.4 GHz ISM band.

  The use band is divided at fixed frequency intervals, and each constitutes a frequency channel. The time axis is divided into time frames having a fixed time length, and channel access is performed based on CSMA / CA (carrier sense multiple access with collision avoidance) in units of time frames. In this case, multiple access within a cell is realized by time division multiple access (TDMA) using a time frame and a slot obtained by dividing the time frame as a unit.

  As shown in FIG. 4, the bandwidth used as a system is 80 MHz, and 80 frequency channels (hereinafter referred to as FCU) having a bandwidth of 1 MHz are provided. The center frequency of the mth FCU (m = 1, 2,..., 80) is (2401 + m) MHz.

  Sixteen FCUs whose FCU numbers end with 1 or 6 are designated as control channels (CCH1 to CCH16), and are used for transmission of control information such as channel assignment. This “channel allocation information” includes information regarding to which mobile terminal the data channel of each frequency band is used. Further, the “channel allocation information” may include information on which spatial region (spatial region number i) the data channel is used for. On the other hand, other FCUs are designated as data channels (DCH1 to DCH64) and used for payload transmission.

  Note that the CCH used for transmission of control information is updated in units of time frames based on the hopping pattern shown in Non-Patent Document 2 described above.

  FIG. 5 is a diagram illustrating a time frame configuration of the radio communication system according to the present embodiment.

  Referring to FIG. 5, the time frame length is 5 ms, the transmission stop period (quiet period) of 200 μs for use condition observation in each frequency channel, and 8 slots used for information transmission (each slot length is 600 μs). Eight slots are allocated to each of the downlink and uplink (DL1 to DL4 and UL1 to UL4). Also, the same number and number of slots are assigned to the mobile station that performs data transmission in both the downlink and the uplink.

  Both the base station AP and the mobile station MS perform spectrum sensing within the transmission stop period, and transmit a control channel packet (hereinafter, CCH packet) on the CCH only when it is determined that the CCH scheduled to be used is unused. To do. At the same time, an appropriate number of unused DCHs are selected by “spatial axis spectrum sensing” as described above, and data channel packets for payload transmission (hereinafter referred to as DCH packets) while performing spectrum division if necessary. Send. The CCH packet includes the results of sensing in each FCU performed on the sender side, information corresponding to the physical header of the DCH packet, such as DCH selection information, transmission payload length, and used MCS (modulation and coding scheme), and a part MAC (media access control) header information is stored.

  Note that the base station AP determines whether or not each FCU can be used based only on its own sensing result. On the other hand, the mobile station MS determines that only the FCU that has been determined to be unused can be used in both the sensing result of the base station AP notified from the base station AP and the result of the sensing performed by itself. Therefore, the mobile station MS does not transmit its own packet when the downlink CCH packet is not normally received.

  FIG. 6 is a diagram showing the concept of shaping the modulated waveform before spectrum division.

  FIG. 6 illustrates processing in the case where duplicate S / P conversion is performed during S / P conversion.

  In modulation waveform shaping, a time-domain single carrier modulation signal with a symbol period Ts and a sampling period Ts / 2, which is band-limited by a root roll-off filter (roll-off rate β), is overlapped as shown in FIG. Is converted into a 2L point frame signal. The frame signal is converted to a frequency domain signal by a 2L-point fast Fourier transform (FFT), and is converted by N BPFs 30-1 to 30-N (center frequency fn, bandwidth wn, n = 1,..., N). The spectrum is divided into N subspectrums. Each of the BPFs 30-1 to 30-N is a root roll-off filter having a roll-off rate βn that is inversely proportional to the bandwidth wn. Each BPF output signal is converted into a frequency point corresponding to a frequency (center frequency fn) to be transmitted by inverse fast Fourier transform (IFFT), and converted into a time domain signal by IFFT. The frequency resolution of IFFT is equal to that of FFT, and the frequency band thereof is equal to or higher than the frequency band of the transmitter.

  Since the output signal in the vicinity of the frame boundary is distorted in the IFFT output signal, the overlapping signal portions are discarded and joined as shown in FIG. Here, if the signals subjected to frequency conversion (fn → fn ′) are connected, the phase of the subsequent frame advances only with respect to the previous frame. It is necessary to perform phase correction of −Φn expressed by the following formulas for the frequency conversion units 40-1 to 40-N for all frequency points in 30-N. However, r is a frame duplication rate and is defined as shown in FIG.

FIG. 7 is a diagram showing allocation of frequency band division when the antenna does not have directivity.

  FIG. 8 is a diagram illustrating a configuration in the case of performing space division multiple access using antenna directivity in the present embodiment.

  First, as a premise for explaining FIG. 8, a case where communication is performed using an omnidirectional antenna will be described with reference to FIG.

  When communication is performed using an omnidirectional antenna (omni antenna) as shown in FIG. 7B, communication data is used when the frequency bands used by other systems are distributed as shown in FIG. 7A. In the frequency band, it is impossible to communicate without causing interference to other systems.

  Next, as shown in FIG. 8B, a case where communication is performed using a directional antenna will be described. In the example shown in FIG. 8 (b), as described above, multiple access within a cell is performed by TDMA, and one slot is assigned to one space area (a space area in one direction where the antenna directivity is suitable). When communicating with each other, in the next slot, it is assumed that the antenna directivity is directed to another space area, and the communication is performed while changing the spatial directivity of the antenna one after another for each slot. I do.

That is, as shown in FIG. 8A, when it is detected that the used frequency bands of other systems are distributed in the #a direction, the #b direction, and the #c direction, the frequency band of the communication data is divided. Thus, the frequency band of the divided communication data is assigned to the data channel of the unused frequency band for each direction. That is, data channels # 1 and # 3 are used for mobile stations existing in the #a direction, data channels # 4 and # 6 are used for mobile stations existing in the #b direction, and #c The mobile stations existing in the direction can communicate with each other using data channels # 2 and # 5. In this case, as shown in FIG. 8A, for example, when communicating with a mobile station in the #a direction, channels # 1 and # 3 are used, but the data channel of this frequency band is The other #b and #c directions are data channels already used in other systems. However, as shown in FIG. 8B, under the control of the control unit 102, the amplitude phase control unit 90, when communicating with the #a direction, Control is performed so that the intensity of directivity with respect to a space area already used in another system is weakened. The same applies to communication in other directions.

  According to such data channel allocation and antenna directivity control, even if the same frequency band is used for the #a direction, the #b direction, and the #c direction, Communication can be performed while suppressing interference. For this reason, compared with the case of FIG. 7, the utilization efficiency of a frequency can be improved.

  In other words, in a communication apparatus using the spectrum division single carrier modulation method in DSA as shown in FIG. 7, since only the measurement of the vacant frequency band on the frequency axis is performed, the vacant frequency band is spatially dispersed. In the case where it exists, a sufficient frequency cannot be effectively used.

  FIG. 9 is a first flowchart illustrating a procedure in which wireless transmission apparatus 1000 performs data channel allocation based on the result of spatial spectrum sensing.

  FIG. 10 is a second flowchart illustrating a procedure in which the wireless transmission device 1000 performs data channel assignment based on the result of spatial spectrum sensing.

  In the following manner, the control unit 102 selects an FCU that reduces the number of spectrum divisions as much as possible and reduces the influence of interference (received signal strength RSSI (Received Signal Strength Indicator) is small). This is because the smaller the number of divisions, the smaller the PAPR (Peak-to-Average Power Ratio) (the load on the amplifier is small) and the smaller the influence of interference, the better the transmission performance.

  First, referring to FIG. 9, the control unit 102 calculates a transmission Byte with a modulation scheme and a coding rate (MCS) that is the maximum transmission capacity from the data amount of data to be transmitted (S100).

  Next, the control unit 102 selects the minimum number of FCUs necessary for transmission of a transmission byte (Byte) from the following combinations (S102).

Number of usable frequency bands: 80 MHz {1, 2, 4, 5, 8, 10, 16, 20, 32, 40}
Of course, the number of usable frequency bands may be another combination.

  Subsequently, the control unit 102 calculates the group average RSSI of the continuous IDLEDCH group based on the sensing result from the detector 80 (S104). Here, the “continuous IDLEDCH group” refers to a group of DCHs that are determined as unused (channel numbers) continuously as a channel when spatial axis sensing is performed. In addition, when the control channel CCH and the data channel DCH are arranged as in the example illustrated in FIG. 4, the upper limit of the number of DCHs that become continuous IDLE is, for convenience of CCH being sandwiched every 5 FCUs. 4 In addition, since such an upper limit depends on the setting of CCH and DCH, it is not necessarily limited to such a value. The “group average RSSI” means “a value obtained by averaging the RSSIs in the FCUs constituting the DCH group having a continuous channel number”.

  Next, the control unit 102 repeats the following processes S106 to S110 within a range equal to or less than a predetermined maximum number of divisions.

  First, in S106, as will be described later, an NCU IDLEDCH group to which FCU allocation is performed is selected (S106).

  Next, the control unit 102 determines whether or not the number of selected FCUs has reached the minimum number of FCUs calculated in S102, and if so, the process proceeds to step S112 (S108).

  On the other hand, if not reached, N is decremented by 1, and the process returns to step S106 again. As described above, this processing means that processing is performed for each element of N = {4, 3, 2, 1} in the case of the example shown in FIG.

  With the above processing, necessary FCUs are allocated from a larger continuous IDLE DCH group. When all the FCUs have been allocated, the final processing is performed (S112), and the processing ends.

  Here, as the last process, for example, when the control unit 102 determines that transmission is possible with an MCS having a lower transmission capacity, the control unit 102 performs a process of lowering the MCS.

  After that, the control unit 102 calculates a weighting factor (weight vector) that causes transmission directivity for the wireless device to be a communication partner with respect to the continuous IDLE DCH group to which the FCU is assigned. Such a weight coefficient is notified to the amplitude phase controller 90, and the amplitude phase controller 90 outputs the weight vector to the weight multipliers 50-1 to 50-N. As described above, since the multiple access in the cell is a time division multiple access, the control unit 102 switches such weight vectors according to the time according to the wireless device of the communication destination.

  FIG. 10 is a flowchart for explaining the process shown in FIG. 9 in more detail.

  The flowchart in FIG. 10 explains the processing step S106 in FIG.

  Referring to FIG. 10, control unit 102 repeats the following processes S200 to S208 for each of N consecutive IDLE DCH groups (hereinafter “continuous IDLEDCH groups”) for the current value of N.

  First, the control unit 102 selects a group having the smallest average RSSI for N FCUs (S200). More specifically, when there are a plurality of “N consecutive IDLE DCH groups” with respect to the same N value, the control unit 102 determines that the group average RSSI has not yet been allocated. The DCHs that make up the smallest group are selected in order.

  Next, the control unit 102 determines whether or not the number of unallocated FCUs is N or more. If the number is N or more (Yes in S202), the “N consecutive IDLE DCH group” that is currently targeted All the FCUs are allocated to all the DCHs (S204).

  On the other hand, when the number of unallocated FCUs is less than N (No in S202), the control unit 102 adds the unallocated FCU to the DCH in the “N consecutive IDLE DCH group” currently targeted. , FCU is allocated (S206).

  Furthermore, the control unit 102 determines that when an unallocated FCU still remains (Yes in S208) and there are other “N consecutive IDLE DCH groups” (Yes in S210), The process returns to S200.

  On the other hand, when there is no unallocated FCU (No in S208), or the “N consecutive IDLE DCH group” does not exist (No in S210), the control unit 102 performs the process in FIG. Return to S108.

  With the configuration described above, radio transmitting apparatus 1000 according to the present embodiment measures a free frequency band that exists spatially and fragmentally on the frequency axis, and for each frequency band used for communication during data communication. By controlling the respective radiation patterns, it is possible to efficiently use vacant frequencies spatially and fragmented on the frequency axis.

  FIG. 11 is a diagram illustrating an example of a configuration of a receiver in a wireless communication system.

  Such a receiver configuration may be provided in the same apparatus together with the transmitter.

  In the following description, a configuration using one antenna will be described as an example. However, by combining with a directivity control technique using a well-known array antenna, reception with spatial directivity can be performed. .

  Referring to FIG. 11, receiving section 200 receives communication data transmitted from a communication destination apparatus by a spectrum division single carrier modulation scheme.

  The reception unit 200 includes a low noise amplification unit 141, a frequency conversion unit 142, a local transmission unit 143, an AD conversion unit 144, an S / P conversion unit 145, a Fourier transform unit 146, and a spectrum demapping unit 147. , An inverse Fourier transform unit 148, a P / S conversion unit 149, and a demodulation unit 150.

  The low noise amplification unit 141 receives an analog signal of communication data received by the antenna 2 and amplifies the received analog signal (reception signal). The frequency converter 142 uses the signal generated by the local transmitter 143 to frequency-convert the received signal and convert it to an equivalent baseband received signal that can be converted by the AD converter 144. The local transmitter 143 generates a signal for frequency conversion in the frequency converter 142. The AD conversion unit 144 converts an analog signal that is an equivalent baseband reception signal into a digital signal. The S / P conversion unit 145 receives the digital signal after AD conversion, and converts the digital signal into a plurality of signals arranged in parallel. The Fourier transform unit 146 receives signals in a plurality of parallel arrays after S / P conversion, and converts the signals in the time domain into signals in the frequency domain by performing fast Fourier transform on these signals in parallel. The spectrum demapping unit 147 receives the signal after the fast Fourier transform, and performs spectrum demapping on the signal. Specifically, the spectrum demapping unit 147 divides the signal after the fast Fourier transform into signals of N frequency bands corresponding to a plurality of frequency bands used in communication by a band pass filter, and the divided N A signal corresponding to one frequency band is combined with a signal of one frequency band by performing frequency conversion on the signal.

  The spectrum demapping unit 147 generates a mapping matrix corresponding to a plurality of frequency bands used in communication of communication data by a method similar to that of the spectrum mapping unit 20, and generates a demapping matrix that is a transposed matrix of the mapping matrix. It is also possible to calculate and use the demapping matrix to combine the signals in the parallel array after the fast Fourier transform into one frequency band.

  The inverse Fourier transform unit 148 performs inverse fast Fourier transform on the signal after the spectrum demapping and returns it to the time domain signal. The P / S conversion unit 149 receives the signal after the inverse fast Fourier transform, and converts the parallel array signal into the serial array. The demodulator 150 receives a serially arranged digital signal after P / S conversion, and digitally demodulates the digital signal.

  Here, also in receiving section 200, a roll-off filter may be used in the subsequent stage of P / S converting section 149. In that case, the inverse Fourier transform unit 148 performs inverse Fourier transform on the signal received from the roll-off filter. When a roll-off filter is used, the S / P conversion unit 145 and the P / S conversion unit 149 may perform overlapping S / P conversion and overlapping P / S conversion. In addition, when overlapping conversion is performed during S / P conversion, the spectrum demapping unit 147 also performs phase correction so that the signal phase does not become discontinuous.

  Embodiment disclosed this time is an illustration of the structure for implementing this invention concretely, Comprising: The technical scope of this invention is not restrict | limited. The technical scope of the present invention is shown not by the description of the embodiment but by the scope of the claims, and includes modifications within the wording and equivalent meanings of the scope of the claims. Is intended.

  12 modulation unit, 14 S / P conversion unit, 16 Fourier transform unit, 20 spectrum mapping unit, 30-1 to 30-N band pass filter, 40-1 to 40-N frequency conversion unit, 50-1 to 50-N , 70 Weight multiplication unit, 60-1 to 60-M up converter, 62 inverse Fourier transform unit, 64 P / S conversion unit, 66 frequency conversion unit, 68 power amplification unit, 80 detector, 90 amplitude phase controller, 100 -1 to 100-M antenna, 102 control unit 1020 Wireless transmission device.

Claims (6)

A wireless communication device that performs communication using an empty frequency band,
Comprising a signal conversion means for converting a data signal into a signal for transmission by a spectrum division single carrier modulation method ;
In the spectrum division single carrier modulation system, a plurality of data channels respectively corresponding to a plurality of predetermined frequency bands for use in data communication are defined in advance,
An array antenna including at least two antennas;
Amplitude phase control means for controlling the amplitude and phase of signals transmitted to and received from each antenna of the array antenna;
Measuring means for measuring the received signal intensity while controlling the radiation pattern of the array antenna by controlling the amplitude phase for each antenna by the amplitude phase control means;
A frequency conversion means for dividing a frequency band used for data transmission and converting the frequency band of the data channel to a data channel corresponding to the empty frequency band;
Based on the measurement result in the measurement means, in the frequency band used for data transmission, an unused empty frequency band depending on other devices and a radiation pattern corresponding to the empty frequency band are determined, and the empty frequency band wherein calculating the amplitude and phase corresponding to the radiation pattern to be used in each, further comprising a control means for performing communication by controlling the amplitude and phase control means,
The control means is a data channel determined to have a lower reception intensity by measurement of the measurement means, and preferentially for a group of data channels in which more data channels are continuously unused, that perform the allocation to idle frequency band of the divided frequency band, the wireless communication device.   Since the amplitude phase control means performs multiple access within a cell by time division multiplexing, for each time division multiplexing slot, the amplitude and phase control means is adapted to the directivity intensity in the direction of the communication destination in the spatial region where other devices are communicating. The wireless communication apparatus according to claim 1, wherein the directivity of the array antenna is controlled so that the directivity intensity with respect to the direction becomes weak. The control means includes
When there are a first group of N consecutive N (N: natural number) unused data channels, allocation of the data channels in the group from the group with low received signal strength to the free frequency band is executed. And
When the allocation to the first plurality of groups is completed and the bandwidth required for transmission cannot be secured, the N value is decremented and detected as a group of consecutive unused data channels. For two or more groups, the frequency band used for data transmission has a predetermined number of divisions for performing the process of allocating to the free frequency band from a group having a low received signal strength for the data channel in the group. The wireless communication apparatus according to claim 1, wherein the wireless communication apparatus repeats until reaching the maximum number of divisions .   The measurement means measures the signal intensity by equally dividing the spatial axis direction of the array antenna and performing sequential sensing while switching the beam direction to each direction. The wireless communication device according to item.   4. The method according to claim 1, wherein the measurement unit performs control so that the directivity of the array antenna is individually directed in a plurality of different directions, and measures the signal intensity in parallel in the plurality of directions. The wireless communication device according to claim 1. A communication method for performing communication using an empty frequency band by a spectrum division single carrier modulation method,
In the spectrum division single carrier modulation scheme, a plurality of data channels respectively corresponding to a plurality of predetermined frequency bands for use in data communication are defined in advance, and the transmitter determines the frequency band used for data transmission. Divide and transmit to the frequency band of the data channel corresponding to the free frequency band of the data channel,
A transmitter controls the amplitude and phase of signals received by each antenna of the array antenna and measures the received signal intensity while controlling the radiation pattern of the array antenna; and
The transmitter determines, based on the measurement result of the signal strength, in the frequency band used for data transmission, an empty frequency band that is not used by other devices and a radiation pattern corresponding to the empty frequency band, respectively. ,
A frequency band divided preferentially with respect to a group of data channels that are determined to have lower reception strength based on the measurement result of the signal strength and in which more data channels are continuously unused. Assigning to the free frequency band of:
A transmitter calculates an amplitude phase corresponding to the radiation pattern used in each of the vacant frequency bands, and performs communication by controlling the amplitude and phase of a signal transmitted from each antenna of the array antenna. A wireless communication method comprising a control step .