JP2009060630A - Radio communication apparatus and radio communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication method extremely excellent in high-quality transmission and high-speed transmission. <P>SOLUTION: A transmission frame is used in which a subcarrier group (painted-out frame in the figure) in which signals of a first transmission system are disposed, and a subcarrier group (blank frame in the figure) in which signals of a second transmission system are disposed are coexistent. Between the first transmission system and the second transmission system, the quantity of information that can be transmitted within a unit time by one subcarrier in the case that the same modulation scheme is used is different. A base station determines whether either the subcarrier group disposed with the signals of the first transmission system or the subcarrier group disposed with the signals of the second transmission system is assigned to each of a plurality of terminals, and determines the number of subcarriers assigned to each terminal for each frame, the transmission frame is formed according to the determination, and the transmission frame is used to transmit a modulation signal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wireless communication method and a wireless communication device, and more particularly to a wireless communication device and a wireless communication method applied to a wireless communication system that is required to wirelessly transmit a large amount of information such as image information at high speed and high quality.

  Conventionally, various methods have been proposed and realized as a method for wirelessly transmitting such a large amount of information at high speed and with high quality. For example, in the CDMA system, transmission data is subjected to spreading processing using a spreading code corresponding to each communication terminal and transmitted. Thereby, in the CDMA system, interference between transmission signals in the radio propagation path can be suppressed, so that a high-quality reception signal can be obtained on the reception side.

  Recently, an OFDM-CDMA system combining an OFDM modulation system and a CDMA system has attracted attention. The OFDM-CDMA system is roughly classified into a time domain spreading system and a frequency domain spreading system. Of these, the frequency domain spreading method will be described.

  FIG. 33 is a schematic diagram showing a state of a digital symbol before modulation processing, and FIG. 34 is a schematic diagram showing an arrangement of chips after modulation processing in the frequency domain spreading method. In the frequency domain spreading method, N digital symbols (FIG. 33), which is a serial data series, are multiplied by a spreading code having a spreading factor M for each symbol. After spreading, M chips are subjected to IFFT processing one symbol at a time in parallel. As a result, N OFDM symbols of M subcarriers are generated. That is, in the frequency domain spreading method, the chips after spreading are arranged in the frequency axis direction (FIG. 34). In other words, the spread chips are arranged on different subcarriers.

  Here, assuming that one digital symbol before modulation processing uses radio resources having time width T and frequency bandwidth B (FIG. 33), one chip has time width N × T and frequency bandwidth B after modulation processing. / N will be used. Therefore, the area per digital symbol in the time-frequency region is M × T × B, which is M times the area occupied by one digital symbol before modulation processing.

  Here, for example, when the number of digital symbols N = 8 and spreading factor M = 8, the signal pattern of OFDM symbols generated by the frequency domain spreading method is as shown in FIG. As shown in this figure, in the frequency domain spreading method, 8 OFDM symbols are sequentially generated at t0 to t7 corresponding to 8 digital symbols distinguished by black and white shading on the time axis. At that time, eight chips in each digital symbol are allocated to different subcarriers f1 to f8, respectively.

  By combining the OFDM modulation method and the CDMA modulation method as described above, efficient reuse can be realized and a statistical multiplexing effect can be obtained. In addition, data transmission at higher speed than single carrier CDMA can be realized. Note that reuse means that the same frequency can be used in adjacent cells. In addition, the statistical multiplexing effect is that when the presence / absence of data is randomly generated by the user, more users' signals can be accommodated than in the case of continuous transmission by reducing energy in a section where the data is not transmitted to each other.

  Incidentally, in recent years, it has been desired to transmit a large amount of information such as a moving image in real time. In order to realize this, it is necessary to transmit data at a very high transmission rate in a limited frequency band.

  The OFDM-CDMA scheme is certainly a scheme that can transmit high-quality data at a relatively high transmission rate, but higher-speed communication is desired as described above.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a wireless communication method and a wireless communication apparatus that are excellent in terms of high-quality transmission and high-speed transmission.

  In order to solve this problem, the present invention adopts the following configuration.

  One aspect of the wireless communication method of the present invention is a wireless communication method in a base station that transmits a modulated signal to a plurality of terminals, a subcarrier group in which signals of a first transmission scheme are arranged, and a second A transmission frame in which a subcarrier group in which a signal of a transmission scheme is arranged is used, and the first transmission scheme and the second transmission scheme use one subcarrier when the same modulation scheme is used. The amount of information that can be transmitted per unit time is different, and a signal of the first transmission method is arranged at each terminal of the plurality of terminals based on feedback information from each terminal that is a communication partner. Decide which of the carrier group and the subcarrier group in which the signal of the second transmission scheme is allocated and the number of subcarriers allocated to each terminal are determined for each frame, and transmitted according to the determination Forming a frame, and transmits the modulated signal using the transmission frame.

  One aspect of the wireless communication device of the present invention is a wireless communication device in a base station that transmits a modulated signal to a plurality of terminals, a subcarrier group in which signals of a first transmission scheme are arranged, and a second A transmission frame in which a subcarrier group in which a signal of a transmission scheme is arranged is used, and the first transmission scheme and the second transmission scheme use one subcarrier when the same modulation scheme is used. The amount of information that can be transmitted per unit time is different, and a signal of the first transmission method is arranged at each terminal of the plurality of terminals based on feedback information from each terminal that is a communication partner. Decide which of the carrier group and the subcarrier group in which the signal of the second transmission scheme is allocated and the number of subcarriers allocated to each terminal are determined for each frame, and transmitted according to the determination Including a transmission frame forming means for forming a frame, and a transmitting means for transmitting the modulated signal using the transmission frame.

  According to the present invention, it is possible to realize a wireless communication method and a wireless communication apparatus that are extremely excellent in terms of high-quality transmission and high-speed transmission, and can improve substantial data transmission efficiency.

  The gist of the present invention is to perform OFDM modulation capable of high-speed transmission on transmission data and perform OFDM-spread modulation which is slightly inferior in terms of high-speed transmission but superior in transmission quality compared to OFDM modulation. The OFDM signal and the OFDM-spread signal formed by these two modulation schemes are selectively assigned to the transmission partner station for transmission. Thus, the communication terminal can achieve both high-speed reception and high-quality reception by adaptively selecting and demodulating one of these two signals according to the reception environment in which the communication terminal is placed.

  In order to realize this, the present invention proposes two transmission methods. First, as shown in FIGS. 1 (A) and 1 (B), the frame structure of the transmission signal, when viewed on the frequency-time axis, the OFDM signal and the OFDM-spread signal in the same frequency band. In this method, the signals are arranged in a mixed manner, and one of the signals is arranged in the frequency direction at each time point, and each signal is transmitted at a different time. As a result, the communication terminal can selectively receive and demodulate the OFDM signal or the OFDM-spread signal by selectively extracting the signal at each time point.

  Second, as shown in FIGS. 2 (A) and 2 (B), when the frame structure of the transmission signal is viewed on the frequency-time axis, an OFDM signal and an OFDM-spread signal are mixed at the same time. In this method, one of the signals is arranged in the time direction in each frequency band, and each signal is transmitted at the same time. As a result, the communication terminal can selectively receive and demodulate the OFDM signal or the OFDM-spread signal by selectively extracting signals in each frequency band.

  Further, as shown in FIG. 3, control information symbols including frame configuration information indicating at which position in the transmission frame the OFDM signal is located and at which position the OFDM-spread signal is arranged to arrange the OFDM signal and the OFDM- Transmit with spread signal.

(Embodiment 1)
In FIG. 4, 1 indicates the overall configuration of the radio base station apparatus according to Embodiment 1 of the present invention. The radio base station apparatus 1 inputs the transmission digital signal D1 to the serial / parallel conversion unit (S / P) 2. The radio base station apparatus 1 spreads the transmission digital signal D1 by a spreading unit 4 using a predetermined spreading code, and then inputs it to a serial / parallel conversion unit (S / P) 5. Further, the radio base station apparatus 1 inputs frame configuration information D5 indicating a frame configuration when the OFDM signal and the OFDM-CDM modulation signal are mixed into the serial / parallel conversion unit (S / P) 8.

  Here, the serial / parallel conversion units (S / P) 2, 5, and 8 form a frame configuration unit 9 and function as frame configuration means. That is, the frame configuration unit 9 configures a transmission frame in which OFDM signals and OFDM-CDM signals are mixed as shown in FIG. 1 (A), FIG. 1 (B), FIG. 2 (A), or FIG. As described above, parallel-serial conversion processing is performed on the transmission data.

  For example, as shown in FIG. 1 (A) and FIG. 1 (B), OFDM signals and OFDM-spread signals are mixedly arranged in the same frequency band, and one of the signals is arranged in the frequency direction at each time point. When configuring a transmission frame, a parallel signal D2 obtained by parallel-serial conversion of the transmission digital signal D1 by the number of subcarriers is output only from the serial / parallel conversion unit (S / P) 2 at a certain point in time. At another point in time, only the serial / parallel converter (S / P) 5 outputs a parallel signal D3 obtained by parallel-serial conversion of the spread transmission digital signal D1 by the number of subcarriers.

  Also, for example, as shown in FIGS. 2A and 2B, the OFDM signal and the OFDM-spread signal are mixedly arranged at the same time, and one of the signals is arranged in the time direction in each frequency band. For example, when the transmission frame arranged in the network is configured, the serial / parallel converter (S / P) 2 outputs two parallel signals D2 corresponding to two subcarriers and the serial / parallel converter (S / P). 5 may output four parallel signals D3 corresponding to four subcarriers.

  The inverse discrete Fourier transform unit (IDFT) performs an inverse discrete Fourier transform process on the input parallel signals D2 and D3 and the frame configuration parallel signal, so that a frame configuration information signal, an OFDM signal, and an OFDM-CDM modulation signal are obtained. Mixed transmission data D4 is formed.

  As described above, the serial / parallel conversion unit (S / P) 2 and the inverse discrete Fourier transform unit (IDFT) 3 function as OFDM modulation means for forming an OFDM signal by performing orthogonal frequency division multiplexing on the transmission signal. To do. The despreading unit 4, the serial / parallel conversion unit (S / P) 5 and the inverse discrete Fourier transform unit (IDFT) 3 perform spreading processing and orthogonal frequency division multiplexing processing on the transmission signal, thereby converting the OFDM-spread signal. It functions as an OFDM-spreading modulation means to be formed.

  The radio unit 6 performs predetermined radio processing such as digital-analog conversion and up-conversion on the transmission signal D4 in which the OFDM signal and the OFDM-CDM signal exist, and sends the processed signal to the transmission power amplification unit 7. The signal amplified by the transmission power amplifier 7 is sent to the antenna AN1. In this way, a mixed signal of an OFDM signal and an OFDM-CDM modulated signal is transmitted from the radio base station apparatus 1.

  Next, FIG. 5 shows a configuration of a communication terminal that receives a mixed signal of an OFDM signal and an OFDM-CDM signal transmitted from radio base station apparatus 1. The communication terminal 10 inputs the received signal S10, which is received by the antenna AN2 and mixed with the OFDM signal and the OFDM-CDM signal, to the radio unit 11. The radio unit 11 performs predetermined radio processing such as down-conversion and analog-digital conversion processing on the received signal S10 and sends the processed signal to the discrete Fourier transform unit (DFT) 12.

  The discrete Fourier transform unit 12 performs a discrete Fourier transform process on the received mixed signal, and sends the received parallel signal obtained thereby to the parallel-serial conversion units (P / S) 13, 14, and 18, respectively. The parallel-serial conversion unit 13 receives the received parallel signal, converts a signal corresponding to the OFDM-modulated signal on the transmission side into a serial signal, and sends it to the subsequent demodulation unit 15. The demodulator 15 performs, for example, QPSK demodulation processing on the input signal. Thereby, transmission data before OFDM modulation is restored.

  On the other hand, the parallel-serial conversion unit 14 receives the received parallel signal, modulates a signal corresponding to the OFDM-CDM modulated signal on the transmission side into a serial signal, and sends it to the subsequent despreading unit 16. The despreading unit 16 despreads the input serial signal using the same spreading code as that on the transmission side, and sends the despread signal to the demodulation unit 17. The demodulator 15 performs, for example, QPSK demodulation processing on the input signal. Thereby, the transmission data before OFDM-CDM modulation is restored.

  The parallel-serial conversion unit 18 performs parallel-serial conversion on the received parallel signal and then sends it to the control information demodulation unit 19. The control information demodulator 19 demodulates the frame configuration information. This frame configuration information is used as control information for the demodulator 15, despreader 16 and demodulator 17. Thereby, the demodulator 15 can demodulate only the OFDM signal from the mixed signal of the OFDM signal and the OFDM-CDM signal. Similarly, the despreading unit 16 and the demodulating unit 17 can demodulate only the OFDM-CDM signal from the mixed signal of the OFDM signal and the OFDM-CDM signal.

  Next, the operation of the first embodiment will be described with reference to FIG. Here, consider a case where the communication terminal A and the communication terminal B exist at a position away from the radio base station apparatus 1, while the communication terminal C exists at a position relatively close to the radio base station apparatus 1. Here, the area AR1 in which the OFDM-CDM signal can be received with high quality is inside the circle indicated by the solid line in the figure, and the area AR2 where the inside of the circle indicated by the dotted line is capable of receiving the OFDM signal with high quality. It has become. The difference in the limit of this region is caused by whether or not the spread spectrum method is used.

  As described above, the radio base station apparatus 1 transmits a signal in which an OFDM signal and an OFDM-CDM signal are mixed to each of the communication terminals A to C. At this time, the communication terminal C that is relatively close to the radio base station apparatus 1 can receive the OFDM signal with good reception quality, so that a signal transmitted using the OFDM modulation scheme can be used as the restoration data.

  On the other hand, the communication terminals A and B that are relatively far from the radio base station apparatus 1 cannot receive the OFDM variable signal in a good reception quality state. Therefore, a signal transmitted using the OFDM-CDM modulation method is used as restoration data. Use it.

  As a result, the communication terminal C can obtain received data with good reception quality and high transmission rate. In addition, the communication terminals A and B can obtain received data with good reception quality although the transmission rate is slightly lower than that of the communication terminal C.

  Here, considering a case where a signal is transmitted using only the OFDM system, all communication terminals A to C can receive a signal having a high transmission rate, but communication terminals A and B far from the radio base station apparatus 1 have reception quality. Deteriorating and in some cases the same data must be sent again, so that the substantial transmission efficiency may be lowered. Considering the case where signals are transmitted using only the OFDM-CDM system, all communication terminals A to C can receive signals with good reception quality, but the transmission rate is lower than that of the OFDM system.

  Thus, according to the above configuration, the transmission data is subjected to OFDM modulation and OFDM-CDM modulation, and two types of modulation signals of OFDM signals and OFDM-CDM signals formed by these two modulation methods are mixed. By transmitting the signal, it is possible to realize the radio base station apparatus 1 and the radio communication method in which high speed communication and high quality communication are compatible.

(Embodiment 2)
In this embodiment, for example, a radio wave propagation environment with a communication terminal such as a reception electric field intensity, a Doppler frequency, an interference wave intensity, a multipath state, a delay profile, an arrival direction, and a polarization state is estimated. Accordingly, it is proposed to switch the modulation scheme of the signal transmitted to each communication terminal in advance between the OFDM signal and the OFDM-CDM signal.

  In this embodiment, the modulation scheme of a signal transmitted to each communication terminal is switched between the OFDM signal and the OFDM-CDM signal in advance according to the required transmission rate from the communication terminal, the required modulation scheme, the required transmission quality, and the like. Propose that.

  That is, as shown in FIGS. 7 and 8, when the number of communication terminals having a good radio wave propagation environment is small, the ratio of the OFDM signal is reduced as shown in FIGS. 7A and 8A. On the other hand, when the number of communication terminals having a good radio wave propagation environment is large, the ratio of the OFDM signal is increased as shown in FIGS. 7B and 8B.

  Select whether to transmit OFDM signal or OFDM-CDM signal according to the radio wave propagation environment such as reception field strength, Doppler frequency, interference wave strength, multipath state, delay profile, direction of arrival, polarization state, etc. The method is not limited to this, and it may be selected whether to transmit an OFDM signal or an OFDM-CDM signal according to the reception quality.

  In addition to or in addition to the radio wave propagation environment and reception quality, depending on the required transmission rate, the required modulation method, and the required transmission quality required by the communication terminal, FIG. As shown in FIG. 8A and FIG. 8B, it may be selected whether to transmit an OFDM signal or an OFDM-CDM signal.

  As a result, in the wireless communication method of this embodiment, only signals with a modulation method that conforms to the radio wave propagation environment of each communication terminal or that meets the request of each communication terminal are transmitted, so that transmission of useless data is suppressed. can do. As a result, limited propagation path resources can be used effectively, and the substantial data transmission efficiency of the radio base station apparatus can be improved.

  Specifically, when reception quality is taken into consideration, as shown in FIG. 9A, there are many communication terminals (communication terminals A to D) that are relatively far from the radio base station apparatus 20, and are close to each other. When the number of communication terminals (communication terminal E) is small, the communication frame configuration is as shown in FIG. 7 (A) or FIG. 8 (A). On the other hand, as shown in FIG. 9B, there are many communication terminals (communication terminals C to E) that are relatively close to the radio base station apparatus 20, and communication terminals (communication terminals A, When the number of B) is small, it is as shown in FIG. 7B or FIG. However, when the information requested by the communication terminal is taken into consideration, the above is not necessarily the case.

  FIG. 10 shows the configuration of the radio base station apparatus 20 of this embodiment. In FIG. 10, 20 indicates a radio base station apparatus as a whole. The radio base station apparatus 20 inputs the received signal received by the antenna AN20 to the radio unit 23. The radio unit 23 performs predetermined radio processing such as down-conversion and analog-digital conversion processing on the input signal, and sends the processed orthogonal baseband signal to the detection unit 24.

  The detector 24 detects the input signal and sends the received signal S20 after detection to the data detector 25. Here, the received signal S20 after detection has a format as shown in FIG. That is, in addition to the data symbols S21 and S23 and the unique word S22, radio wave propagation environment estimation information S24 and request information S27 are added. The radio wave propagation environment estimation information S24 is information such as the multipath of the signal received by the communication terminal, the electric field strength, the Doppler frequency, the interference power, the interference wave strength, the delay profile, the arrival direction of the radio wave, and the polarization state. The request information S27 is information indicating the required transmission rate, the required modulation method, and the required transmission quality requested by each communication terminal.

  The data detection unit 25 divides the detected received signal S20 into data symbols S21 and S23, radio wave propagation environment estimation information S25, and request information S27, and outputs the data symbols S21 and S23 as received data, The environment estimation information S25 and the request information S27 are sent to the frame configuration determination unit 26.

  The frame configuration determination unit 26 determines the frame configuration of the transmission signal based on the radio wave propagation environment estimation information S25 and the request information S27, and outputs this as the frame configuration information S26. Specifically, whether to transmit an OFDM signal or an OFDM-CDM signal to each communication terminal is selected based on the radio wave propagation environment estimation information S25 and the request information S27, and FIG. 7 and FIG. A transmission frame such as 8 is determined. Then, the frame configuration determination unit 26 sends the determined frame configuration information S 26 to each serial / parallel conversion unit (S / P) 30, 33, 36 in the frame configuration unit 37.

  For example, as a result of measuring the delay profile as the radio wave propagation environment information S25, when the information indicating that there are a plurality of delayed waves having a high electric field strength (the influence of the delayed waves is large) is received, the OFDM-CDM method is selected. If a signal indicating that there is no delayed wave with high electric field strength is received, the OFDM method is selected.

  Further, as a result of measuring the polarization state as the radio wave propagation environment information S25, if the received polarization state is significantly different from the transmitted polarization, the OFDM-CDM system is selected and received. If a signal indicating that the polarization states are substantially equal is received, the OFDM scheme is selected.

  Next, the transmission system of the radio base station apparatus 20 will be described. The radio base station apparatus 20 inputs the transmission digital signal D20 to the serial / parallel conversion unit (S / P) 30. Further, the frame configuration information S26 determined by the frame configuration determination unit 26 is input to the serial / parallel conversion unit 30. The serial-parallel conversion unit 30 performs parallel conversion processing on the input transmission digital signal D20 based on the frame configuration information S26, and sends the parallel signal D21 to the inverse discrete Fourier transform unit (IDFT) 31.

  The transmission digital signal D20 is input to the spreading unit 32. The spreader 32 spreads the transmission digital signal D20 using a predetermined spread code, and sends the spread signal obtained thereby to the serial / parallel converter (S / P) 33. Further, the frame configuration information S26 is input to the serial / parallel converter 33. The serial-parallel conversion unit 33 performs parallel conversion processing on the input signal based on the frame configuration information S26 and sends the parallel signal D22 obtained thereby to the inverse discrete Fourier transform unit (IDFT) 31. Further, the frame configuration information S26 is input to the inverse discrete Fourier transform unit 31 via the serial / parallel conversion unit 36.

  The inverse discrete Fourier transform unit 31 performs an inverse discrete Fourier transform process on the input parallel signal D21, OFDM-CDM parallel signal D22, and frame information signal. Thereby, the transmission signal D23 in which the frame information signal, the OFDM signal, and the OFDM-CDM signal are mixed is formed.

  The radio unit 34 performs predetermined radio processing such as digital-analog conversion and up-conversion on the transmission signal D23, and sends the processed signal to the transmission power amplification unit 35. The signal amplified by the transmission power amplifier 35 is sent to the antenna AN20. In this way, the radio base station apparatus 20 selects either the OFDM signal or the OFDM-CDM signal according to the radio wave propagation environment or request of each communication terminal, and the OFDM signal and / or OFDM- addressed to a plurality of communication terminals. A CDM signal is arranged in a transmission frame and transmitted.

  Next, FIG. 12 shows the configuration of a communication terminal that receives a mixed signal of an OFDM signal and an OFDM-CDM signal transmitted from radio base station apparatus 20. In FIG. 12, parts corresponding to those in FIG. And the part which attaches | subjects and shows the same code | symbol has the function similar to the part mentioned above, Therefore It abbreviate | omits description.

  A radio wave propagation environment estimation unit 43 is provided in the reception system of the communication terminal 40. Based on the output of the discrete Fourier transform unit 12, the radio wave propagation environment estimation unit 43 multipaths the received signal, electric field strength, Doppler frequency, interference power, interference wave strength, delay profile, radio wave arrival direction, polarization state, etc. Is measured as the propagation environment, and the estimated radio wave propagation environment estimation information D41 is sent to the transmission data forming unit 44.

  The transmission data forming unit 44 receives the transmission data D40, the radio wave propagation environment estimation information D41 estimated by the radio wave propagation environment estimation unit 43, and the request information D42. The transmission data forming unit 44 forms the transmission data S20 having the frame configuration shown in FIG. 11 and sends this to the orthogonal baseband signal forming unit 45. The transmission quadrature baseband signal formed by the quadrature baseband signal forming unit 45 is subjected to predetermined radio processing such as digital-analog conversion and up-conversion by the radio unit 46 and is transmitted to the subsequent transmission power amplifying unit 47. The signal amplified by the transmission power amplifier 47 is sent to the antenna AN40.

  Here, the request information D42 may be the transmission rate, modulation method, transmission quality requested by the user using the communication terminal, or when a transmission medium such as an image, sound, etc. is determined. The required transmission rate, modulation method, and transmission quality determined according to the transmission medium. As described above, the communication terminal 40 transmits the radio wave propagation environment information and the request information between the own station and the radio base station apparatus 20 to the radio base station apparatus 20.

  Thus, according to the above configuration, the transmission data is subjected to OFDM modulation and OFDM-CDM modulation, and among the two types of modulation signals of the OFDM signal and the OFDM-CDM signal formed by these two modulation methods, In addition to the effect of the first embodiment, by transmitting only the signal of the modulation method suitable for the radio wave propagation environment of each communication terminal or according to the request of each communication terminal, transmission of useless data Can be suppressed. As a result, limited propagation path resources can be used effectively, and the substantial data transmission efficiency of the radio base station apparatus can be improved.

  Incidentally, switching between the OFDM scheme and the OFDM-CDM scheme is performed when the terminal has the switching initiative, and the terminal selects either the OFDM scheme or the OFDM-CDM scheme from the estimated radio wave propagation environment and request information. The request information is transmitted to the base station. Then, the frame configuration determination unit of the base station determines, based on the request information from the terminal, whether to transmit data to the terminal using the OFDM scheme or to transmit data using the OFDM-CDM. Output.

  On the other hand, when the base station has a switching initiative, the terminal transmits the estimated radio wave propagation environment information and request information to the base station. Then, the frame configuration determination unit 26 of the base station determines whether to transmit data by OFDM or OFDM-CDM according to radio wave propagation environment information, request information, and communication traffic from the terminal. The frame configuration signal S26 is output.

(Embodiment 3)
In the second embodiment described above, the case where the signal transmitted to each communication terminal is switched between the OFDM signal and the OFDM-CDM signal according to the reception quality of the communication terminal or the request from the communication terminal has been described. In the form, when switching between these two modulation signals, several preferable arrangements of OFDM signals and OFDM-CDM signals mixed in one transmission frame are proposed.

  (1) First, as shown in FIG. 13, a method is proposed in which the times t10 to t11 for transmitting OFDM-CDM signals and the times t11 to t12 for transmitting OFDM signals are fixed within one frame.

  Here, FIG. 13 shows a frame structure of one burst of a signal transmitted from the base station, and symbols A, B, C, D, and E are terminal A, terminal B, terminal C, and terminal, respectively. D, transmission symbols addressed to terminal E are shown. The arrangement of OFDM symbols and OFDM-CDM symbols in one burst is fixed. That is, 4 × 6 symbols for OFDM symbols and 6 × 6 symbols for OFDM-CDM symbols are fixedly arranged in one frame with respect to the time-frequency axis.

  9A, with respect to the base station 20, the terminal A, the terminal B, the terminal C, and the terminal D exist in the OFDM-CDM reception area, and only the terminal E exists in the OFDM reception area. In this case, as shown in FIG. 13A, the base station 20 divides the times t10 to t11 for transmitting the OFDM-CDM signal into a plurality of times, and is addressed to the terminal A, the terminal B, the terminal C, or the terminal D at each time. The OFDM-CDM signal is transmitted. The base station 20 transmits an OFDM signal addressed to the terminal E at times t11 to t12 when transmitting the OFDM signal.

  On the other hand, as shown in FIG. 9B, for the base station 20, terminals A and B exist in the OFDM-CDM reception area, and terminals C, D, and E exist in the OFDM reception area. In this case, the base station 20 divides the time t10 to t11 for transmitting the OFDM-CDM signal into a plurality of times as shown in FIG. 13B, and the OFDM-address addressed to the terminal A or the terminal B at each time. A CDM signal is transmitted. The base station 20 divides the time t11 to t12 for transmitting the OFDM signal into a plurality of times, and transmits the OFDM signal addressed to the terminal C, the terminal D, or the terminal E at each time.

  As described above, by fixing the times t10 to t11 for transmitting the OFDM-CDM signal and the times t11 to t12 for transmitting the OFDM signal within one transmission frame, the receiving side performs OFDM for the received frame. -Since the time for performing the CDM demodulation process and the time for performing the OFDM demodulation process can be separated, in each of the terminals A to E, whether the signal addressed to itself is an OFDM-CDM processed signal or an OFDM processed signal Regardless of this, it becomes possible to easily demodulate the signal addressed to the own station.

  Incidentally, FIG. 13 shows only symbols for data addressed to each terminal, but if a control symbol indicating at which time the symbol of each terminal is allocated is arranged at the head position of the frame, for example, A terminal that receives a transmission frame can easily demodulate data addressed to itself based on the control symbol. The same applies to FIGS. 14 to 20 described later.

  For example, consider terminal C. When terminal C is configured as shown in FIG. 12, terminal C performs OFDM-CDM demodulation processing at times t10 to t11 in one transmission frame, and performs OFDM demodulation processing at times t11 to twelve.

  Actually, when the signal addressed to the terminal C is a signal that has been subjected to OFDM-CDM processing as shown in FIG. 13A, the signal addressed to itself is transmitted via the despreading unit 16 and the demodulating unit 15. Only is demodulated and output. On the other hand, when the signal addressed to the terminal C is an OFDM-processed signal as shown in FIG. 13B, nothing is output via the despreading unit 16 and the demodulating unit 17. Only the signal addressed to the local station is demodulated and output via the parallel-serial converter 13 and the demodulator 14. Incidentally, it can be recognized, for example, based on control information (not shown) added to the head of the frame at which time in the OFDM section t11 to t12 the signal addressed to the terminal E is allocated. That is, the terminal C recognizes the allocation position of the OFDM symbol addressed to itself by the control information demodulator 19 and selects and extracts the symbol addressed to itself by the demodulator 17.

  In this way, the time t10 to t11 for transmitting the OFDM-CDM signal and the time t11 to t12 for transmitting the OFDM signal are fixed within one transmission frame, and the signals addressed to the terminals A to E are converted to the OFDM-CDM signal and the OFDM. When the signals are appropriately switched with each other, each signal is arranged so that the OFDM-CDM signal and the OFDM signal addressed to each terminal are accommodated within each fixed time. In addition, when the transmission partner station receives and demodulates the transmission frame, it is possible to separate the time for demodulating the OFDM-CDM signal and the time for demodulating the OFDM signal, thereby facilitating demodulation processing. . As a result, system design can be facilitated.

  (2) FIG. 14 shows a second method in which an OFDM signal and an OFDM-CDM signal are mixed in one transmission frame. In this method, the same frame as in the case of (1) is configured except that the OFDM-CDM signal is multi-code multiplexed using different spreading codes for each terminal. That is, the time t10 to t11 for transmitting the OFDM-CDM signal and the time t11 to t12 for transmitting the OFDM signal are fixed in one transmission frame, and the OFDM-CDM signal is multi-code multiplexed, and a chip addressed to each terminal. Are spread in the frequency axis direction and the time direction.

  14A shows a frame format when transmitting OFDM-CDM signals to terminals A to D and transmitting OFDM signals to terminal E, and FIG. 14B shows OFDM-CDM for terminals A and B. This is a frame format when a signal is transmitted and an OFDM signal is transmitted to terminals C, D, and E.

  In the case of this method, similarly to the case of (1), the times t10 to t11 for transmitting the OFDM-CDM signal and the times t11 to t12 for transmitting the OFDM signal are fixed in one transmission frame, and the terminals A to E are fixed. System design is easy because each signal is arranged so that the OFDM-CDM signal and OFDM signal addressed to each terminal can be accommodated within each fixed time when the addressed signal is appropriately switched between the OFDM-CDM signal and OFDM signal. Can be

  (3) FIG. 15 shows a third method in which OFDM signals and OFDM-CDM signals are mixed in one transmission frame. In this method, time t20 to t21 and t20 to t23 for transmitting an OFDM-CDM signal and times t21 to t22 and t23 to t22 for transmitting an OFDM signal in one transmission frame are set as the number of terminals transmitting each modulation signal. It can be made variable accordingly.

  For example, in FIG. 15A, since the terminal that transmits the OFDM signal is only the terminal E, the times t21 to t22 assigned to the OFDM signal in one transmission frame are shortened. On the other hand, in FIG. 15B, since the terminals transmitting the OFDM signal are terminals C, D, and E, the times t23 to t22 assigned to the OFDM signal in one transmission frame are longer than the times t21 to t22. Yes.

  Incidentally, in this method, since a predetermined time is assigned to each of the terminals A to E, it is possible to impart fairness to the transmission data amount for each terminal.

  For example, compared to the case of FIG. 13 described in (1), in the case of FIG. 13, the time for transmitting each modulated signal is fixed regardless of the number of terminals transmitting the OFDM-CDM signal and the OFDM signal. A situation occurs in which the amount of transmission data to the terminal increases, but the transmission data to other terminals decreases.

  Specifically, when the terminal that transmits the OFDM signal is only the terminal E as shown in FIG. 13A, all the times t11 to t12 can be assigned to the transmission signal addressed to the terminal E. A lot of data can be received. On the other hand, since the data of four terminals must be sent at time t10 to t11 for the other terminals A to D, the transmission data per terminal is naturally reduced.

  Thus, the time allocated to each terminal is fixed within one transmission frame, and the times t20 to t21 and t20 to t23 for transmitting the OFDM-CDM signal and the times t21 to t22 and t23 to t22 for transmitting the OFDM signal are By making it variable according to the number of terminals transmitting each modulation signal, it is possible to perform fair data transmission to each terminal in terms of the amount of transmission data.

  (4) FIG. 16 shows a fourth method in which OFDM signals and OFDM-CDM signals are mixed in one transmission frame. In this method, the same frame as in the case of (3) is configured except that the OFDM-CDM signal is multi-code multiplexed using different spreading codes for each terminal. That is, the time allocated to each terminal is fixed within one transmission frame, and the times t20 to t21 and t20 to t23 for transmitting OFDM-CDM signals and the times t21 to t22 and t23 to t22 for transmitting OFDM signals are modulated. In addition to being variable according to the number of terminals that transmit signals, the OFDM-CDM signal is multicode multiplexed, and chips addressed to each terminal are spread in the frequency axis direction and the time direction.

  Incidentally, FIG. 16A shows a frame format when an OFDM-CDM signal is transmitted to terminals A to D and an OFDM signal is transmitted to terminal E. FIG. 16B shows an OFDM-CDM for terminals A and B. This is a frame format when a signal is transmitted and an OFDM signal is transmitted to terminals C, D, and E.

  Also in this method, similarly to the method (3), it is possible to perform fair data transmission to each terminal in terms of the amount of transmission data.

  (5) FIG. 17 shows a fifth method in which an OFDM signal and an OFDM-CDM signal are mixed in one transmission frame. In this method, the subcarrier for transmitting the OFDM-CDM signal and the subcarrier for transmitting the OFDM signal are fixed.

  That is, as shown in FIG. 9A, with respect to the base station 20, terminal A, terminal B, terminal C, and terminal D exist in the OFDM-CDM reception area, and only terminal E exists in the OFDM reception area. In this case, the base station 20 divides a plurality of subcarriers in the frequency bands f10 to f11 for transmitting the OFDM-CDM signal as shown in FIG. An OFDM-CDM signal addressed to each station is transmitted by being assigned to an OFDM-CDM signal addressed to terminal C or terminal D. The base station 20 transmits an OFDM signal addressed to the terminal E on subcarriers in the frequency bands f11 to f12 for transmitting the OFDM signal.

  On the other hand, as shown in FIG. 9B, for the base station 20, terminals A and B exist in the OFDM-CDM reception area, and terminals C, D, and E exist in the OFDM reception area. In this case, the base station 20 divides a plurality of subcarriers in the frequency band f10 to t11 for transmitting the OFDM-CDM signal as shown in FIG. It allocates and transmits to the OFDM-CDM signal addressed to the terminal B. In addition, the base station 20 divides the subcarriers in the frequency bands f11 to f12 for transmitting the OFDM signal into a plurality of parts, and assigns the divided subcarriers to the OFDM signal addressed to the terminal C, the terminal D, or the terminal E and transmits them.

  As described above, by fixing the frequency bands f10 to f11 for transmitting the OFDM-CDM signal and the frequency bands f11 to f12 for transmitting the OFDM signal within one transmission frame, the reception side performs the processing on the received frame. Since the frequency band for OFDM-CDM demodulation processing and the frequency band for OFDM demodulation processing can be separated, each terminal A to E is a signal addressed to its own station that is subjected to OFDM-CDM processing or OFDM processing. Regardless of whether it is a signal or not, it becomes possible to easily demodulate a signal addressed to the own station.

  That is, in this way, if the frequency bands f10 to f11 for transmitting the OFDM-CDM signal and the frequency bands f11 to f12 for transmitting the OFDM signal are fixed within one transmission frame, for example, the frequency in the radio unit 11 of FIG. If the signals in the bands 10 to f11 and the frequency bands f11 to f12 are separated, the received signal can be separated into an OFDM-CDM signal and an OFDM signal. A signal in the frequency band 10 to f11 can be subjected to OFDM-CDM demodulation processing by the DFT 12, P / S 14, the despreading unit 16 and the demodulation unit 17 to obtain a demodulated signal, and the signal in the frequency band f11 to f12 can be obtained. The signal can be subjected to OFDM demodulation processing by the DFT 12, P / S 13, and demodulator 15 to obtain a demodulated signal.

  (6) FIG. 18 shows a sixth method in which an OFDM signal and an OFDM-CDM signal are mixed in one transmission frame. In this method, a frame similar to that in the case of (5) is configured except that the OFDM-CDM signal is multi-code multiplexed using a different spreading code for each terminal. That is, in one transmission frame, the frequency bands f10 to f11 for transmitting the OFDM-CDM signal and the times f11 to f12 for transmitting the OFDM signal are fixed, and the OFDM-CDM signal is multi-code multiplexed, The chip is spread in the frequency axis direction and the time direction.

  18A shows a frame format when transmitting OFDM-CDM signals to terminals A to D and transmitting OFDM signals to terminal E, and FIG. 18B shows OFDM-CDM for terminals A and B. This is a frame format when a signal is transmitted and an OFDM signal is transmitted to terminals C, D, and E.

  Also in this method, as in the case of (5), the frequency bands f10 to f11 for transmitting the OFDM-CDM signal and the frequency bands f11 to f12 for transmitting the OFDM signal are fixed in one transmission frame, and each terminal A When the signals addressed to E are appropriately switched between the OFDM-CDM signal and the OFDM signal, each signal is arranged so that the OFDM-CDM signal and the OFDM signal addressed to each terminal are within each fixed frequency band. Design can be facilitated.

  (7) FIG. 19 shows a seventh method in which an OFDM signal and an OFDM-CDM signal are mixed in one transmission frame. In this method, terminals that transmit modulated signals in frequency bands f20 to f21 and f20 to f23 for transmitting OFDM-CDM signals and frequency bands f21 to f22 and f23 to f22 for transmitting OFDM signals in one transmission frame. It is variable according to the number.

  For example, in FIG. 19A, since the terminal that transmits the OFDM signal is only the terminal E, the frequency bands f21 to f22 assigned to the OFDM signal in one transmission frame are narrow. On the other hand, in FIG. 19B, since the terminals transmitting the OFDM signal are terminals C, D, and E, the frequency bands f23 to f22 assigned to the OFDM signal in one transmission frame are wider than the frequency bands f21 to f22. It has become.

  Incidentally, in this method, since a predetermined frequency band (subcarrier) is assigned to each of the terminals A to E, it is possible to impart fairness to the transmission data amount for each terminal.

  For example, compared to the case of FIG. 17 described in (5), in the case of FIG. 17, the frequency band for transmitting each modulation signal is fixed regardless of the number of terminals transmitting the OFDM-CDM signal and the OFDM signal. A situation occurs in which the amount of transmission data for a certain terminal increases but the transmission data for another terminal decreases.

  Thus, in one transmission frame, the frequency band (subcarrier) assigned to each terminal is fixed, and the frequency bands f20 to f21 and f20 to f23 for transmitting the OFDM-CDM signal and the frequency band f21 to transmit the OFDM signal are transmitted. By making f22 and f23 to f22 variable according to the number of terminals transmitting each modulated signal, it is possible to perform fair data transmission to each terminal in terms of transmission data amount.

  (8) FIG. 20 shows an eighth method of mixing an OFDM signal and an OFDM-CDM signal in one transmission frame. In this method, the same frame as in the case of (7) is configured except that the OFDM-CDM signal is multi-code multiplexed using different spreading codes for each terminal. That is, in one transmission frame, the frequency band assigned to each terminal is fixed, and the frequency bands f20 to f21 and f20 to f23 for transmitting OFDM-CDM signals and the frequency bands f21 to f22 and f23 to f22 for transmitting OFDM signals are defined. In addition to making it variable according to the number of terminals transmitting each modulated signal, the OFDM-CDM signal is multi-code multiplexed, and chips addressed to each terminal are spread in the frequency axis direction and the time direction.

  Incidentally, FIG. 20A shows a frame format when an OFDM-CDM signal is transmitted to terminals A to D and an OFDM signal is transmitted to terminal E. FIG. 20B shows an OFDM-CDM for terminals A and B. This is a frame format when a signal is transmitted and an OFDM signal is transmitted to terminals C, D, and E.

  In the case of this method as well as the method (7), it is possible to perform fair data transmission to each terminal in terms of the amount of transmission data.

(Embodiment 4)
In this embodiment, there is proposed a method for reducing the influence received by terminals when adjacent base stations transmit signals in which OFDM-CDM signals and OFDM signals are mixed.

  A system configuration as shown in FIG. 21 is assumed. In FIG. 21, the communication limit of the OFDM-CDM signal of the base station A is AR11, and the communication limit of the OFDM signal is AR10. Further, the communication limit of the OFDM-CDM of the base station B is AR21, and the communication limit of the OFDM signal is AR20.

  Here, since the OFDM-CDM signal is a signal addressed to a terminal far from the base station as compared with the OFDM signal, the OFDM-CDM signal can be further improved in the reception quality at the terminal of the OFDM-CDM signal. It is conceivable to make the signal transmission level higher than that of the OFDM signal. However, when the transmission level of the OFDM-CDM signal is increased, there is a possibility that the reception quality in the OFDM communication region is deteriorated due to interference of the OFDM signal of another adjacent cell.

  Therefore, in this embodiment, as shown in FIG. 22, the distance ra from the origin of the IQ plane of the signal point to be subjected to OFDM-CDM processing indicated by a black circle ● in the figure is the OFDM indicated by a white circle ○ in the figure. In addition to making the signal point to be processed larger than the distance rb from the origin of the IQ plane, the phase of the signal point ● to be subjected to OFDM-CDM processing and the phase of the signal point to be subjected to OFDM processing are arranged differently. It is made to do. Incidentally, FIG. 22 shows the arrangement of signal points when QPSK modulation is performed, but this is not limited to QPSK modulation, and the same applies to other modulation schemes such as 16-value QAM.

  Thereby, by increasing the signal level of the OFDM-CDM signal, it is possible to improve the reception quality of the OFDM-CDM signal and suppress the deterioration of the reception quality due to the interference of the OFDM-CDM signal with respect to the OFDM signal in another adjacent cell. Will be able to.

  The configuration of the base station for forming such a transmission signal is shown in FIG. In FIG. 23, in which the same reference numerals are assigned to the parts corresponding to FIG. 4, the radio base station device 50 includes a modulation unit 51 that forms a modulation signal for performing OFDM processing, and modulation for performing OFDM-CDM processing. Different modulation processes are performed by the modulation section 52 that forms a signal. That is, the modulation unit 52 performs a modulation process such that the signal level of the symbol after modulation is larger than that of the modulation unit 51, and the phase of the symbol after modulation is different from the phase of the symbol after modulation of the modulation unit 51. Apply appropriate modulation processing. Specifically, such processing can be easily performed by shifting the mapping position of signal points.

  In the above configuration, as shown in FIG. 21, the terminal X exists outside the OFDM communication limit AR10 of the base station A and inside the OFDM-CDM communication limit AR11 of the base station A. From the base station A to the OFDM- Assume that a CDM signal is received. At this time, in the terminal X, the interference from the OFDM-CDM signal transmitted to the other station by the base station B is hardly received because the spreading code is different, and the interference from the OFDM signal addressed to the other station has a different signal point position. I hardly receive it. As a result, a high-quality OFDM-CDM demodulated signal can be obtained.

  Considering the case where the terminal X exists within the communication limit AR10 of the OFDM signal of the base station A and receives the OFDM signal from the base station A, the OFDM-CDM signal transmitted from the base station B to other stations is considered. Interference is hardly received because the signal point position is different. As a result, a high-quality OFDM demodulated signal can be obtained.

  Here, the case where the signal level of the OFDM-CDM signal is made larger than the signal level of the OFDM signal has been described, but conversely, the signal level of the OFDM signal is made larger than the signal level of the OFDM-CDM signal. Even in the case, the same effect can be obtained.

  Further, it is determined whether to select which signal level to increase depending on whether the terminal X is within the communication limit AR10 of the OFDM signal or the communication limit AR11 of the OFDM-CDM signal. It is also effective to make it. For example, when the terminal X is within the OFDM communication limit AR10, if the transmission level of the OFDM signal is made larger than the transmission level of the OFDM-CDM signal, the OFDM signal addressed to the own station can be received at a sufficient reception level. In addition to the above, it becomes difficult to be influenced by the OFDM-CDM signal transmitted from the base station B.

  On the other hand, when the terminal X is within the OFDM-CDM communication limit AR11, if the transmission level of the OFDM-CDM signal is made larger than the transmission level of the OFDM signal, the OFDM-CDM signal addressed to the own station is sufficient. In addition to being able to receive at the reception level, it is less susceptible to the influence of the OFDM signal transmitted from the base station B.

  Thus, by making the signal point of the OFDM-CDM signal different from the signal point of the OFDM signal, different modulation signals from other adjacent cells (if the signal addressed to the own station is an OFDM signal, If it is an OFDM-CDM signal and the signal addressed to itself is an OFDM-CDM signal, it is possible to obtain a high-quality demodulated signal by suppressing interference due to (OFDM signals in other cells).

  Thus, according to the above configuration, when the OFDM signal and the OFDM-CDMA signal are mixed and transmitted, the signal point positions of the OFDM signal and the OFDM-CDM signal are not matched, so that the signal is transmitted by another station. In addition to the effects of the first and second embodiments, the reception quality can be further improved.

(Embodiment 5)
First, the principle of this embodiment will be described. A radio wave with a high frequency is suitable for high-speed data communication because the attenuation is large and the communication area is narrow, but the frequency band can be widened. On the other hand, a radio wave with a low frequency is inferior to a radio wave with a high frequency in terms of high-speed data communication because the frequency band cannot be widened, but the communication area can be widened because attenuation is small.

  Focusing on this point, in this embodiment, terminals that exist in a communication area close to the base station communicate using high-frequency radio waves, and terminals that exist in a communication area far from the base station. For this, it is proposed to communicate using low frequency radio waves. Accordingly, high-speed data communication can be performed while ensuring communication quality in a communication area close to the base station, and communication in which deterioration of quality is suppressed can be performed in a communication area far from the base station. As a result, high-speed communication and high-quality communication compatible with each other can be realized.

  FIG. 24 shows an example of the positional relationship between the base station 100 and the terminal 200 in this embodiment, AR31 shows the communication limit of the transmission signal transmitted by the base station 100 in the frequency 1 GHz band, and AR30 shows the base The communication limit of the transmission signal transmitted by the station 100 in the frequency 30 GHz band is shown. In this embodiment, when the terminal 200 exists inside the communication limit AR30, communication is performed in the frequency 30GH band, and when the terminal 200 exists outside the communication limit AR30 and inside the communication limit AR31. Communication is performed at a frequency of 1 GHz.

  In the case of this embodiment, the terminal 200 estimates the radio wave propagation environment based on the received signal from the base station 100, and which frequency band is determined based on the radio wave propagation environment information received by the base station 100 from the terminal 200. Is determined to be transmitted to the terminal 200. Note that which frequency band signal is to be transmitted is not limited to the case of determining based on the radio wave propagation environment estimated by terminal 200, but may be determined based on the radio wave propagation environment estimated by base station 100, for example. Or may be determined according to other requests from the terminal 200 (for example, required transmission rate, required modulation method, required transmission quality, etc.), or may be determined simply based on distance information from the base station 100. Also good.

  FIG. 25 shows the configuration of radio base station apparatus 100 of this embodiment. First, the transmission system will be described. Radio base station apparatus 100 inputs transmission digital signal D100 to modulation sections 101 and 102. Further, the control signal S100 determined by the transmission method determination unit 111 is input to the modulation units 101 and 102. When the control signal S100 indicates that communication is performed at 1 GHz, the modulation unit 101 modulates the transmission digital signal into a transmission orthogonal baseband signal for 1 GHz communication and outputs the modulated signal. When the control signal S100 indicates that communication is performed at 30 GHz, the modulation unit 102 modulates the transmission digital signal into a transmission orthogonal baseband signal for 30 GHz communication and outputs the modulated signal.

  The radio units 103 and 104 receive a transmission orthogonal baseband signal for 1 GHz communication and a transmission orthogonal baseband signal for 30 GHz communication, respectively, and a control signal S100. When the control signal S100 indicates that communication is performed in the 1 GHz band, the radio unit 103 up-converts a transmission orthogonal baseband signal for 1 GHz communication to a radio frequency in the 1 GHz band. When the control signal S100 indicates that communication is performed in the 30 GHz band, the radio unit 104 up-converts the transmission orthogonal baseband signal for 30 GHz communication to a radio frequency in the 30 GHz band.

  Thereby, when the control signal S100 indicates that communication is performed in the 1 GHz band, the transmission digital signal D100 is converted to a transmission signal in the 1 GHz band and is output from the antenna 105, while the control signal S100 is communicated in the 30 GHz band. In the case where the transmission digital signal D100 is indicated, the transmission digital signal D100 is output as a 30 GHz band transmission signal from the antenna 106. Incidentally, in the case of this embodiment, the antenna 105 outputs a transmission signal having a band of 5 MHz with a center frequency of 1 GHz, and the antenna 106 outputs a transmission signal having a band of 100 MHz with a center frequency of 30 GHz. ing.

  FIG. 26 shows a format of a transmission signal output from the antennas 105 and 106. In addition to the data symbols, the antennas 105 and 106 inform the estimation symbol for estimating the radio wave propagation environment on the terminal 200 side, and which frequency band the terminal 200 is transmitting to which signal in the frequency band. A control symbol for controlling the reception demodulation operation is added and transmitted. These estimation symbols and control symbols may be added before and after the data symbols, or may be transmitted at regular intervals.

  Returning to FIG. 25, the configuration of the reception system of radio base station apparatus 100 will be described. When the radio base station apparatus 100 receives a signal from the terminal 200 via the antenna 107, the radio base station apparatus 100 transmits the signal to the demodulation unit 109 via the radio unit 108. The signal demodulated by the demodulator 109 is sent to the signal separator 110. The signal separation unit 110 separates the demodulated reception signal into a data signal S200, radio wave propagation environment information S201, and request information S202. Among these, the radio wave propagation environment information S201 and request information S202 are transmitted to the transmission method determination unit 110. Send it out. Here, the radio wave propagation environment estimation information S201 is information indicating reception quality when the terminal 200 receives a signal from the radio base station apparatus 100. The request information S202 is information indicating the required transmission rate, the required modulation scheme, and the required transmission quality requested by the terminal 200.

  In addition to the radio wave propagation environment estimation information S201 and request information S202, communication traffic information S203 from an RNC (Radio Network Controller) is input to the transmission method determination unit 111, and the transmission method determination unit 111 is based on these information. , It is determined whether to transmit a 1 GHz band signal or a 30 GHz band signal to each terminal 200, and the determination result is output as a control signal S100 for controlling the modulation units 101 and 102 and the radio units 103 and 104 To do. Specifically, as long as communication traffic permits, a 1 GHz band signal is transmitted when the propagation propagation environment is bad, and a 30 GHz band signal is transmitted when the radio wave propagation environment is good.

  As described above, the radio base station apparatus 100 according to the present embodiment transmits a transmission digital signal to be transmitted to the terminal as a signal in the 1 GHz band in accordance with the radio wave propagation environment information and request information transmitted from the communication partner terminal. The transmission is performed by selecting whether to transmit with a signal of 30 GHz band.

  Next, the configuration of communication terminal 200 that communicates with radio base station apparatus 100 will be described using FIG. The communication terminal 200 can selectively receive and demodulate a 1 GHz band signal or a 30 GHz band signal transmitted from the radio base station apparatus 100.

  First, the receiving system will be described. The communication terminal 100 inputs a signal received by the antenna 201 to the 1 GHz band reception processing unit 203 and inputs a signal received by the antenna 202 to the 30 GHz band reception processing unit 204. The radio unit 205 of the 1 GHz band reception processing unit 203 multiplies the received signal by a 1 GHz carrier wave. On the other hand, the radio unit 206 of the 30 GHz band reception processing unit 204 multiplies the received signal by a 30 GHz carrier wave. As a result, the received signals in the 1 GHz band and the 30 GHz band are detected, and the processed signals are sent to the demodulation units 207 and 208 and the radio wave propagation environment estimation units 209 and 210.

  Demodulation sections 207 and 208 demodulate the radio-processed signal and send the demodulated signal to selection section 211. The selection unit 211 responds to the control information included in the demodulated signal (that is, information indicating whether the base station 100 has transmitted transmission data addressed to the terminal in the 1 GHz band or the 30 GHz band). 1 or the output signal from the demodulator 208 is selectively output. Thus, even when transmission data is transmitted by being superimposed on a 1 GHz band carrier by the radio base station apparatus 100 or transmitted by being superimposed on a 30 GHz band carrier wave, the transmission data is received and demodulated to obtain a received digital signal. Can be done.

  The radio wave propagation environment estimation units 209 and 210 estimate the communication state in the 1 GHz band and the communication state in the 30 GHz band based on the known signals for estimating the radio wave propagation environment among the signals output from the radio units 205 and 206. Specifically, for each of the 1 GHz band and 30 GHz band, by measuring the received signal multipath, electric field strength, Doppler frequency, interference power, jamming wave strength, delay profile, arrival direction of radio waves, polarization state, etc. Estimate the radio wave propagation environment with the base station.

  Here, the signal propagated in the 1 GHz band and the signal propagated in the 30 GHz band are different in deterioration (for example, as described above, the signal propagated in the 30 GHz band is more attenuated in the propagation path. ), The estimated value estimated by the radio wave propagation environment estimation unit 209 and the estimated value estimated by the radio wave propagation environment estimation unit 210 are different. The radio wave propagation environment estimation information S300 estimated by the radio wave propagation environment estimation unit 209 and the radio wave propagation environment estimation information S301 estimated by the radio wave propagation environment estimation unit 210 are sent to the information generation unit 212 of the transmission system.

  In addition to the two radio wave propagation environment estimation information S300 and S301, transmission data D200 and request information S302 are input to the information generation unit 212. The information generation unit 212 forms a frame format signal as shown in FIG. 28 from these data and information. This signal is modulated by the subsequent modulation unit 213, up-converted to a radio frequency by the radio unit 214, and then output from the antenna 215.

  As described above, in the communication terminal 200, the 1 GHz band signal and the 30 GHz band signal transmitted from the radio base station apparatus 100 can be selectively demodulated, and the communication state in the 1 GHz band and the 30 GHz band can be transmitted to the radio base station apparatus 100. The communication status at can be notified.

  Thus, according to the above configuration, one of the different frequency bands is selected according to the radio wave propagation environment with the transmission partner station or a request from the transmission partner station, and transmission data is transmitted in the selected frequency band. By doing so, it is possible to realize communication compatible with both high-speed communication and high-quality communication.

(Other embodiments)
In Embodiment 1 described above, the case where the radio base station apparatus is configured as shown in FIG. 4 has been described. However, the radio base station apparatus may be configured as shown in FIG. That is, in the radio base station apparatus 300 of FIG. 29 in which parts corresponding to those in FIG. 4 are assigned the same reference numerals, the connection positions of the spreading unit 4 and the serial / parallel conversion unit 5 are reversed. That is, each data after serial / parallel conversion is spread by the spreading unit 4.

  Similarly, in the first embodiment, the case where the communication terminal is configured as shown in FIG. 5 has been described. However, the communication terminal may be configured as shown in FIG. That is, in the communication terminal 310 of FIG. 30 shown with the same reference numerals corresponding to those in FIG. 5, the connection positions of the despreading unit 16 and the parallel serial conversion unit 14 are reversed. That is, the signal subjected to the despreading process by the despreading unit 16 is parallel-serial converted.

  Moreover, you may comprise the transmission part 21 of the wireless base station apparatus 20 in the above-mentioned Embodiment 2 as shown in FIG. That is, in the transmission unit 320 shown in FIG. 31 in which the same reference numerals are assigned to the parts corresponding to those in FIG. 10, the connection positions of the spreading unit 32 and the serial / parallel conversion unit 33 are reversed. That is, each data after serial / parallel conversion is subjected to diffusion processing by the diffusion unit 32.

  Similarly, the receiving unit 42 of the communication terminal 40 according to Embodiment 2 may be configured as shown in FIG. That is, in the receiving unit 330 shown in FIG. 32, in which parts corresponding to those in FIG. 12 are given the same reference numerals, the connection positions of the despreading unit 16 and the parallel serial conversion unit 14 are reversed. That is, the signal subjected to the despreading process by the despreading unit 16 is parallel-serial converted.

  In the above-described first to third embodiments, the communication terminals 10 and 40 restore the original data of the OFDM signal and the original data of the OFDM-CDM signal from the mixed signal of the OFDM signal and the OFDM-CDM signal. The mixed signal is passed through the parallel-serial converter 13 and the demodulator 15 to restore the original data of the OFDM signal, and is also passed through the parallel-serial converter 14, the despreader 16 and the demodulator 17. Although the case where the original data of the CDM signal is restored has been described, the present invention is not limited to this.

  For example, the original data of the OFDM signal may be restored by extracting the OFDM signal from the mixed signal in advance and passing it through the parallel-serial conversion unit 13 and the demodulation unit 15. Similarly, an OFDM-CDM signal is extracted from the mixed signal in advance, and the original data of the OFDM-CDM signal is restored by passing it through the parallel-serial conversion unit 14, the despreading unit 16, and the demodulation unit 17. Also good.

  Further, in the above-described Embodiment 2, the case where the signal to be transmitted to each communication terminal is adaptively switched between the OFDM signal and the OFDM-CDM signal according to the reception state of the communication terminal to be transmitted has been described. The present invention is not limited to this, and when the distance to the communication terminal is less than a predetermined value according to the distance to the communication terminal, the OFDM signal is transmitted to the communication terminal, and the distance to the communication terminal is equal to or greater than the predetermined value. In this case, even if an OFDM-CDM signal is transmitted to the communication terminal, the same effect as in the second embodiment described above can be obtained.

  In the first to fifth embodiments described above, the radio communication apparatus according to the present invention is applied to the radio base station apparatus and transmission from the radio base station apparatus to the communication terminal is described as an example. However, the present invention is not limited to this. It can be widely applied to communication between communication stations that perform wireless communication with each other.

  Further, in the above-described embodiment, the signal to be transmitted is adaptively switched between the OFDM signal and the OFDM-CDM signal according to the radio wave propagation environment with the communication partner station, or the signal having a high frequency and the signal having a low frequency are switched. However, the modulation scheme may be switched adaptively based on any one of the delay profile, direction of arrival, and polarization state sent from the communication partner station. Good.

  For example, when the delay profile measured at the communication partner station indicates that there are a plurality of delayed waves with high electric field strength (the influence of the delayed waves is large), the transmission signal is subjected to QPSK modulation, When a signal indicating that there is no high delay wave is received, 16-level QAM modulation is performed.

  In addition, when the polarization state measured at the communication partner station indicates that the received polarization state is significantly different from the transmitted polarization, the transmission signal is subjected to QPSK modulation and the received polarization state is received. When a signal indicating that the wave states are substantially equal is received, 16-value QAM modulation is performed.

  In this way, communication compatible with both high-speed communication and high-quality communication can be performed as in the above-described embodiment.

The figure which shows an example of a communication frame structure by this invention The figure which shows an example of a communication frame structure by this invention The figure which shows an example of arrangement | positioning in the communication frame of the control information symbol which carries frame structure information The block diagram which shows the structure of the wireless base station apparatus which concerns on Embodiment 1 of this invention. FIG. 2 is a block diagram illustrating a configuration of a communication terminal according to the first embodiment. The figure which shows arrangement | positioning of the radio base station apparatus and communication terminal with which description of operation | movement of Embodiment 1 is provided. The figure which shows an example of the communication frame structure which concerns on Embodiment 2 of this invention. The figure which shows an example of the communication frame structure which concerns on Embodiment 2 of this invention. The figure which shows arrangement | positioning of the radio base station apparatus and communication terminal with which it uses for description of switching of the communication frame of Embodiment 2 The block diagram which shows the structure of the radio base station apparatus which concerns on Embodiment 2 of this invention. The figure which shows the structure of the transmission data of the communication terminal of Embodiment 2. FIG. A block diagram showing a configuration of a communication terminal according to a second embodiment The figure which shows the example of a communication frame structure when the time which transmits an OFDM-CDM signal and the time which transmits an OFDM signal are fixed. The figure which shows the example of a communication frame structure when the time which transmits an OFDM-CDM signal and the time which transmits an OFDM signal are fixed, and an OFDM-CDM signal is multicode multiplexed. The figure which shows the example of a communication frame structure when the time which transmits an OFDM-CDM signal according to the number of transmitting terminals and the time which transmits an OFDM signal are made variable. The figure which shows the example of a communication frame structure at the time of making the time which transmits an OFDM-CDM signal and the time which transmits an OFDM signal variable according to the number of transmitting terminals, and carrying out multicode multiplexing of the OFDM-CDM signal The figure which shows the example of a communication frame structure at the time of fixing the frequency band which transmits an OFDM-CDM signal, and the frequency band which transmits an OFDM signal. The figure which shows the example of a communication frame structure at the time of fixing the frequency band which transmits an OFDM-CDM signal, and the frequency band which transmits an OFDM signal, and carrying out the multicode multiplexing of the OFDM-CDM signal The figure which shows the example of a communication frame structure at the time of making variable the frequency band which transmits an OFDM-CDM signal, and the frequency band which transmits an OFDM signal according to the number of transmitting terminals. The figure which shows the example of a communication frame structure at the time of making variable the frequency band which transmits an OFDM-CDM signal according to the number of transmitting terminals, and the frequency band which transmits an OFDM signal, and carrying out multicode multiplexing of the OFDM-CDM signal. The figure which shows the communication limit of the OFDM signal in Embodiment 4, the communication limit of an OFDM-CDM signal, and the position of a communication terminal The figure which shows the signal point position of the OFDM signal and OFDM-CDM signal in Embodiment 4 Block diagram showing a configuration of a radio base station apparatus according to the fourth embodiment The figure which shows the relationship between the communication limit of the radio wave of 1 GHz band, and the communication limit of the radio wave of 30 GHz band Block diagram showing a configuration of a radio base station apparatus according to the fifth embodiment The figure which shows the content of the transmission signal from the wireless base station apparatus in Embodiment 5 Block diagram showing a configuration of a communication terminal according to the fifth embodiment The figure which shows the content of the transmission signal from the communication terminal in embodiment The block diagram which shows the structure of the transmission part of the wireless base station apparatus by other embodiment The block diagram which shows the structure of the receiving part of the communication terminal by other embodiment The block diagram which shows the structure of the transmission part of the wireless base station apparatus by other embodiment The block diagram which shows the structure of the receiving part of the communication terminal by other embodiment Schematic diagram showing the state of digital symbols before OFDM-CDM processing Schematic diagram showing the arrangement of each chip after modulation processing in the frequency domain spreading method Schematic diagram showing the signal pattern of OFDM symbols generated by the frequency domain spreading method

Explanation of symbols

1, 20, 50, 100, 300 Radio base station apparatus 2, 5, 8, 30, 33, 36 Serial / parallel converter (S / P)
3, 31 Inverse discrete Fourier transform (IDFT)
4, 32 Spreading unit 6, 11, 23, 34, 46, 103, 104, 108, 205, 206, 214 Radio unit 7, 35, 47 Transmission power amplification unit 9 Frame configuration unit 10, 40, 200, 310 Communication terminal 12 Discrete Fourier Transform (DFT)
13, 14, 18 Parallel serial converter (P / S)
15, 17, 109, 207, 208 Demodulation unit 16 Despreading unit 19 Control information demodulation unit 24 Detection unit 25 Data detection unit 26 Frame configuration determination unit 43, 209, 210 Radio wave propagation environment estimation unit 44 Transmission data formation unit 45 Orthogonal base Band signal forming unit 101, 102, 213 Modulating unit AN1, AN2, 105, 106, 107, 201, 202, 205 Antenna D1, D100 Transmission digital signal D2, D21 OFDM parallel signal D3, D22 OFDM-CDM parallel signal D4, D23 , D200 Transmission data D5, S26 Frame configuration information S10, S20 Reception signal S25, D41, S201, S300, S301 Radio wave propagation environment estimation information S27, D42, S202, S302 Request information S100 Control information S203 Communication traffic information AR1 OFDM-CDM reception area AR2 OFDM reception area AR10, AR 20 OFDM communication limit AR11, AR21 OFDM-CDM communication limit AR 30 30 GHz band communication limit AR 31 1 GHz band communication limit

Claims (10)

A wireless communication method in a base station that transmits a modulated signal to a plurality of terminals,
A transmission frame in which a subcarrier group in which a signal of the first transmission scheme is arranged and a subcarrier group in which a signal of the second transmission scheme is arranged is used, and the first transmission scheme and the The second transmission scheme is different in the amount of information that can be transmitted per unit time in one subcarrier when the same modulation scheme is used,
Based on feedback information from each terminal which is a communication partner, a subcarrier group in which the signal of the first transmission method is arranged and a signal of the second transmission method are arranged in each terminal of the plurality of terminals. Decide which subcarrier group to assign and the number of subcarriers assigned to each terminal for each frame, and form a transmission frame according to the decision,
A wireless communication method for transmitting the modulated signal using the transmission frame. The radio communication method according to claim 1, wherein the feedback information includes radio wave propagation environment estimation information between the base station and each terminal, and request information regarding a transmission rate, a modulation method, and transmission quality requested by each terminal. When forming the transmission frame,
The radio communication method according to claim 1 or 2, wherein the control information symbols are arranged on fixed subcarriers. When forming the transmission frame,
The wireless communication method according to claim 1 or 2, wherein the control information symbols are arranged at a predetermined time. The radio communication method according to claim 3 or 4, wherein the control information symbol includes information indicating a frame configuration of the transmission frame. A wireless communication device in a base station that transmits a modulated signal to a plurality of terminals,
A transmission frame in which a subcarrier group in which a signal of the first transmission scheme is arranged and a subcarrier group in which a signal of the second transmission scheme is arranged is used, and the first transmission scheme and the The second transmission scheme is different in the amount of information that can be transmitted per unit time in one subcarrier when the same modulation scheme is used,
Based on feedback information from each terminal which is a communication partner, a subcarrier group in which the signal of the first transmission method is arranged and a signal of the second transmission method are arranged in each terminal of the plurality of terminals. A transmission frame forming means for deciding which of the subcarrier groups to allocate and the number of subcarriers allocated to each terminal for each frame, and forming a transmission frame in accordance with the determination;
Transmitting means for transmitting the modulated signal using the transmission frame;
A wireless communication device. The radio communication apparatus according to claim 6, wherein the feedback information includes radio wave propagation environment estimation information between the base station and each terminal, and request information regarding a transmission rate, a modulation method, and transmission quality requested by each terminal. The frame forming means includes
The radio communication apparatus according to claim 6 or 7, further comprising a control information symbol arranged on a fixed subcarrier. The frame forming means includes
The radio communication apparatus according to claim 6 or 7, further comprising arranging the control information symbols at a predetermined time. The radio communication apparatus according to claim 8 or 9, wherein the control information symbol includes information indicating a frame configuration of the transmission frame.

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