JP5020043B2 - Wireless communication apparatus and wireless communication system - Google Patents

Description

  The present invention relates to a radio communication apparatus, and more particularly to a radio communication apparatus and a radio communication system that convert an input signal from a time domain to a frequency domain signal and rearrange the converted spectrum to obtain good reception characteristics.

  As the amount of data communication has increased in recent years, the need for a mobile communication system having higher frequency utilization efficiency has increased, and various studies on a one-cell reuse cellular system using the same frequency band in all cells have been promoted. It has been. The E-UTRA (Evolved Universal Terrestrial Radio Access) system, which is one of the 1-cell reuse cellular systems and is being standardized around the 3rd Generation Partnership Project (3GPP), uses OFDMA (Orthogonal Frequency) as the downlink transmission method. The Division Multiple Access (SC) method is considered as the most promising candidate for the uplink transmission method, the Single Carrier-Frequency Division Multiple Access (SC-FDMA) method.

  Among these, the OFDMA scheme is a scheme in which a terminal accesses each resource block divided by time and frequency using an OFDM signal excellent in resistance to multipath fading, but has a high PAPR (Peak-to-Average Power). Ratio) characteristics, it is not suitable as an uplink transmission method with severe transmission power limitation. On the other hand, the SC-FDMA scheme is suitable for uplink transmission because the PAPR characteristic can be kept low and a wide coverage can be ensured as compared to a multicarrier scheme such as OFDM (for example, see Non-Patent Document 1). .

  FIG. 8 shows the configuration of a terminal apparatus when this SC-FDMA scheme is used for uplink transmission. As shown in FIG. 8, in a terminal apparatus using the SC-FDMA scheme, first, transmission section error correction encoding is performed in encoding section 1000, and modulation section 1001 performs modulation. Next, the modulated transmission signal is subjected to serial / parallel conversion in the S / P conversion unit 1002 and then converted into a frequency domain signal in a DFT (Discrete Fourier Transform) unit 1003. The transmission signal thus converted into a frequency domain signal is mapped to a subcarrier used for transmission in subcarrier mapping section 1004. The mapping at this time is performed based on mapping information transmitted from the base station apparatus, received by the receiving antenna unit 1011, demodulated by the receiving unit 1014 via the radio unit 1012 and the A / D conversion unit 1013, and used for transmission. Zeros are inserted in the subcarriers that are not allowed. In the E-UTRA system, a mapping called Localized using continuous subcarriers and a mapping called Distributed using subcarriers separated by a fixed interval are being studied.

  The transmission signal mapped on the subcarrier used for transmission in subcarrier mapping section 1004 is then input to IFFT (Inverse Fast Fourier Transform) section 1005, where it is converted from a frequency domain signal to a time domain signal. . A CP (Cyclic Prefix) insertion unit 1007 inserts a CP (a signal obtained by copying the symbol after IFFT) via the P / S conversion unit 1006, and the D / A conversion unit 1008 converts the signal into an analog signal. After that, the radio unit 1009 up-converts the radio frequency band signal into a radio frequency band signal and transmits it from the transmission antenna unit 1010. The transmission signal generated in this way has a feature that the PAPR is lower than that of the multicarrier signal.

  FIG. 9 shows the configuration of a base station apparatus that receives a signal transmitted from the terminal apparatus of FIG. As shown in FIG. 9, in the base station apparatus that receives the SC-FDMA signal, first, after the signal received by the antenna unit 2000 is converted to a frequency that can be A / D converted by the radio unit 2001, An A / D converter 2002 converts the digital signal. Next, symbol synchronization is established by the synchronization unit 2003, and after the CP is removed for each symbol by the CP removal unit 2004, the time domain signal is transmitted to the frequency domain in the FFT unit 2006 via the S / P conversion unit 2005. Converted to a signal.

  The signal received by the base station apparatus is obtained by frequency-division multiplexing signals transmitted from a plurality of terminals, and mapping information (which terminal apparatus uses which subcarrier is determined by the scheduling unit 2011 in advance). Subcarrier demapping section 2007 collects the used subcarriers for each terminal device based on the information). Then, equalization section 2008 performs equalization processing on the received subcarriers grouped for each terminal device, and IDFT section 2009 converts from a frequency domain signal to a time domain signal, and then performs demodulation / error correction decoding. In section 2010, transmission data for each terminal device is reproduced.

  Also, a known signal for reception level measurement is transmitted together with the transmission data signal in the terminal device, and the received reception level measurement signal is sent from the FFT unit 2006 to the scheduling unit 2011 in the base station device. Based on the measurement result of the reception level using this signal, the scheduling unit 2011 performs scheduling (determining subcarrier mapping information) in consideration of the propagation status of each terminal. The mapping information determined in the scheduling unit 2011 is modulated in the transmission unit 2012, passes through the D / A unit 2013, the radio unit 2014, and the like, and is transmitted from the antenna unit 2015 to each terminal. This mapping information is used for transmission on the terminal side after the next frame.

An SC-ASA (Single Carrier-Adaptive Spectrum Allocation) method has been proposed as a method for realizing more flexible spectrum control than the SC-FDMA method (Non-Patent Document 2). This SC-ASA system is a system in which a spectrum used for transmission is freely arranged according to the reception status of signals from each terminal, and the PAPR is slightly higher than that in the case of performing mapping such as Localized and Distributed as described above. However, reception characteristics can be greatly improved by selecting subcarriers that can provide high received signal power. In the SC-ASA scheme, it is possible to keep the PAPR low by dividing the spectrum of the transmission signal into several blocks (adjacent spectrum groups) and mapping in blocks. When the SC-ASA scheme is used for uplink transmission, the terminal apparatus has the same configuration as in FIG. 8, but the mapping information notified from the base station apparatus is good according to the reception status of the signal from each terminal. It is instructed to use only subcarriers that provide characteristics.
3GPP, TSG RAN WG1 on LTE, R1-050702, “DFT-spread OFDM with Pulse Shaping Filter in Frequency Domain in Evolved UTRA Uplink” The 17th Annual IEEE International Symposium on Personal, Mobile and Mobile Radio Communications, "MICROSCOPIC SPECTRUM CONTROL TECHN LIFE CONTROL TECH NITE CURR ER FE L

  The SC-FDMA scheme and the SC-ASA scheme described above are schemes in which a modulated signal is spread and transmitted in the frequency domain, and therefore the spectrum of the transmission signal has a different amplitude for each subcarrier. That is, a transmission spectrum having a high power and a transmission spectrum having a low power are mixed even in one transmission symbol subjected to the DFT processing by the DFT unit 1003 in FIG. In this way, when a transmission spectrum having a high power and a transmission spectrum having a low power are mixed, if the transmission spectrum having a high power falls significantly due to fading, the demodulation will have a large effect, and the demodulation characteristics will be There is a problem that it deteriorates greatly.

  Note that the SC-ASA scheme is a scheme for improving reception characteristics by selecting only subcarriers that can obtain high received signal power for transmission in consideration of propagation path conditions, but there is a bias in amplitude. The transmission spectrum is not considered.

  The present invention has been made in view of such circumstances, and a radio communication device capable of obtaining good reception characteristics even when a transmission spectrum having high power and a transmission spectrum having low power are mixed An object is to provide a wireless communication system.

  (1) In order to achieve the above object, the present invention has taken the following measures. That is, the radio communication apparatus according to the present invention is a radio communication apparatus that converts transmission data from a time domain signal to a frequency domain signal, assigns the spectrum of the converted signal to subcarriers, and performs transmission. A rearrangement determination unit that calculates power of each spectrum of the signal converted into a signal of the region and determines the rearrangement information of the spectrum in consideration of the calculated power of each spectrum and the propagation path state; and the rearrangement determination A spectrum interleaving unit that performs spectrum interleaving based on the rearrangement information determined by the unit.

  As described above, spectrum interleaving is performed in consideration of the power of each spectrum and the propagation path condition. For example, it is possible to reduce the probability that a spectrum having high power is transmitted in a propagation path where reception power is reduced. Therefore, by returning the spectrum to the original arrangement on the wireless communication device side of the communication destination, even when a transmission spectrum with a high power and a transmission spectrum with a low power are mixed, good reception characteristics (error rate characteristics) Can be obtained.

  (2) In the wireless communication apparatus according to the present invention, the rearrangement determination unit divides the spectrum of the signal converted into the frequency domain signal into a plurality of groups each composed of a plurality of adjacent spectra, It is characterized in that the average power of the constituting spectrum is calculated, and the permutation information of the spectrum in units of groups is determined in consideration of the calculated average power of each group and the propagation path condition.

  In this way, spectrum interleaving is performed on a group-by-group basis in consideration of the average power and propagation path conditions of each group, so that it is possible to obtain better error rate characteristics than when no interleaving is performed. At the same time, there is a possibility that deterioration of PAPR characteristics can be reduced as compared with the case where interleaving is performed in units of subcarriers. Further, it is possible to reduce the information amount of the rearrangement information notified to the communication destination wireless communication apparatus.

  (3) The wireless communication device of the present invention includes an in-group spectrum number determination unit that determines the number of spectra constituting the group, and configures the group according to transmission power or a distance from a communication destination wireless communication device. It is characterized by changing the number of spectra.

  As described above, the number of spectrums constituting the group is changed according to the transmission power or the distance to the communication destination wireless communication device. For example, it is possible to flexibly change according to the transmission power or the distance to the communication destination wireless communication device. It becomes possible to adjust the number of groups.

  (4) In the wireless communication apparatus of the present invention, the in-group spectrum number determination unit increases the number of spectrums constituting the group when the transmission power is high or the distance to the communication destination wireless communication apparatus is long. It is characterized by that.

  In this way, when the transmission power is high or the distance from the communication destination wireless communication device is long, the number of spectrums constituting the group is increased. For example, this communication device is a base station device. The number of groups can be reduced when there is a high possibility of distortion in the signal due to the nonlinear amplifier, such as being located far from the wireless communication device and requiring high transmission power. It is possible to avoid the influence of distortion caused by the amplifier.

  (5) In the wireless communication apparatus of the present invention, the rearrangement determination unit limits the number of spectrums or the number of spectrum groups to be rearranged among the spectrums of signals converted into frequency domain signals. It is said.

  As described above, since the number of spectrums or the number of spectrum groups to be rearranged is limited, it is possible to reduce the information amount of the rearrangement information notified to the communication destination wireless communication apparatus.

  (6) The radio communication apparatus according to the present invention is characterized in that the reordering determination unit determines the reordering information for transmitting a spectrum having high power on a subcarrier having a better propagation path condition.

  In this way, since rearrangement information for transmitting a spectrum with high power with subcarriers with better propagation path conditions is determined, it is assigned to subcarriers with higher received power in order from the spectrum with higher power. Interleaving is possible, and better reception characteristics (error rate characteristics) can be obtained as compared to the case where no interleaving is performed.

  (7) In the wireless communication apparatus of the present invention, the rearrangement determination unit determines rearrangement information for shifting the spectrum in consideration of the power of each spectrum of the signal converted into the frequency domain signal and the propagation path condition. The spectrum interleaving unit shifts the spectrum based on the rearrangement information determined by the rearrangement determination unit.

  As described above, the spectrum is shifted in consideration of the power of each spectrum and the propagation path condition. For example, the shift is performed by transmitting the spectrum having the highest power through the propagation path where the highest power is obtained. It is possible to obtain a better error rate characteristic compared to the case where there is no error. In addition, since the arrangement of adjacent spectra is maintained, the continuity of the original spectrum can be maintained and the PAPR characteristics can be prevented from being deteriorated. Furthermore, it is possible to reduce the information amount of the rearrangement information notified to the communication destination wireless communication apparatus.

  (8) In the wireless communication apparatus of the present invention, the rearrangement determining unit transmits the spectrum having the highest power among the spectrum of the signal converted into the signal in the frequency domain by using the subcarrier having the best propagation path condition. It is characterized by determining replacement information.

  In this way, since the rearrangement information for transmitting the spectrum having the highest power with the subcarrier having the best propagation path condition is determined, the spectrum having the highest power can be allocated to the subcarrier having the best propagation path condition. Thus, it is possible to obtain better reception characteristics (error rate characteristics) than when no shift is performed.

  (9) In the wireless communication apparatus of the present invention, the rearrangement determining unit calculates an average power of each spectrum or each group in the transmission frame.

  In this way, since the average power of each spectrum or each group in the transmission frame is calculated, a spectrum having an average high power in the transmission frame can be transmitted in a propagation path where higher received power can be obtained. As compared with the case where rearrangement is not performed, better reception characteristics can be obtained, and the amount of rearrangement information to be notified to the communication destination wireless communication apparatus can be greatly reduced.

  (10) The wireless communication device of the present invention is a wireless communication device that converts a received signal from a time domain signal to a frequency domain signal, and is based on spectrum rearrangement information rearranged by a communication destination wireless communication device. And a spectrum deinterleaving unit that restores the spectrum of the signal converted into the frequency domain signal to the original arrangement.

  Thus, since the spectrum of the signal converted into the frequency domain signal is restored to the original arrangement based on the spectrum rearrangement information rearranged by the communication destination wireless communication apparatus, for example, the communication destination wireless communication apparatus Even in the case where the spectrum having high power is rearranged so as to be transmitted by subcarriers with better propagation path conditions, the spectrum can be restored to the original arrangement. For this reason, it is possible to reduce the probability that a spectrum having a high power is transmitted in a propagation path in which the reception power is reduced, so that it is possible to obtain good reception characteristics (error rate characteristics).

  (11) The wireless communication system of the present invention also includes a time / frequency converter that converts transmission data from a signal in the time domain to a signal in the frequency domain, and power that each spectrum of the signal converted into the signal in the frequency domain has. A reordering determination unit that determines the reordering information of the spectrum in consideration of the calculated power and propagation path condition of each spectrum, and interleaving of the spectrum based on the reordering information determined in the reordering determination unit A spectrum interleaving unit that performs transmission, a wireless transmission device that performs transmission by allocating the interleaved spectrum to subcarriers, and a signal that is transmitted from the wireless transmission device and is rearranged by the wireless transmission device Based on the information, a spectrum deinterleaver that restores the spectrum of the signal to its original arrangement A radio receiving apparatus to obtain, and a.

  In this way, in the wireless transmission device, spectrum interleaving is performed in consideration of the power of each spectrum and the propagation path condition. For example, the probability that a spectrum having a high power is transmitted in a propagation path where reception power is reduced. Therefore, even if a transmission spectrum with high power and a transmission spectrum with low power are mixed, it is possible to return the spectrum to the original arrangement on the wireless receiver side of the communication destination. (Error rate characteristic) can be obtained. Further, in the wireless reception device, the spectrum of the signal converted into the frequency domain signal based on the rearrangement information of the spectrum rearranged in the communication destination wireless transmission device is restored to the original arrangement. Even in the case where a spectrum having high power is rearranged so as to be transmitted by subcarriers with better propagation path conditions, the spectrum can be restored to the original arrangement. For this reason, it is possible to reduce the probability that a spectrum having a high power is transmitted in a propagation path in which the reception power is reduced, so that it is possible to obtain good reception characteristics (error rate characteristics).

  According to the present invention, spectrum interleaving is performed in consideration of the power of each spectrum and the propagation path condition. For example, the probability that a spectrum having a high power is transmitted in a propagation path where received power is reduced is reduced. Therefore, by returning the spectrum to the original arrangement on the wireless communication device side of the communication destination, even when a transmission spectrum having a high power and a transmission spectrum having a low power are mixed, good reception characteristics (error rate) Characteristic).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
In the present embodiment, an interleaving method is shown in consideration of a propagation path condition and a power distribution of a transmission spectrum so as to be allocated to subcarriers from which a high reception power is obtained in order from a transmission spectrum having a high transmission power.

  First, a conceptual diagram of spectrum interleaving according to the present embodiment is shown in FIG. FIG. 1 shows an example of a reception level under a frequency selective fading environment and a transmission signal spectrum of the SC-FDMA scheme (Localized arrangement). The left side shows before interleaving and the right side shows after interleaving. However, here, the number of DFT points (number of subcarriers to which transmission spectrum is allocated) is 8, and only the transmission spectrum for one symbol is shown. Further, the numbers described above the reception level are given from 1 in descending order of the reception level.

  The left diagram of FIG. 1 shows a state in which a spectrum having a high power as indicated by f5 is transmitted in a round 8 propagation path (subcarrier) in which received power is reduced. In such a case, reception is performed. The characteristics will deteriorate. On the other hand, when the interleaving method in the present embodiment is used, rearrangement is performed in the spectrum arrangement as shown in the right diagram of FIG. This spectrum rearrangement is performed so that a spectrum having a high power is transmitted in a propagation path from which a higher reception power is obtained. For example, the spectrum having the highest transmission power (f5) can obtain the highest reception power. Will be transmitted in the round 1 propagation path. The second highest transmission power spectrum (f2) is the propagation path of circle 2 where the second highest reception power is obtained, and the lowest transmission power spectrum (f3) is the lowest reception power propagation of circle 8. It will be transmitted on the road.

  With respect to the signal transmitted with such rearrangement, the receiving side performs demodulation processing after returning the spectrum rearranged on the transmitting side to the original arrangement. By performing such rearrangement, it is possible to reduce the probability that a spectrum having high power is transmitted in a propagation path where reception power is reduced, and therefore, better reception characteristics than when no rearrangement is performed. Can be obtained.

  FIG. 1 shows an example in which the spectrum is rearranged based on the power distribution for one symbol, and even when a plurality of symbols are transmitted continuously (framed), different power is used for each symbol. Good reception characteristics can be obtained by performing different sorts according to the distribution. However, as described above, since the receiving side performs processing for returning the spectrum rearranged on the transmitting side to the original arrangement, it is necessary to notify information on the rearrangement from the transmitting side to the receiving side. When performing different sorts, a lot of sort information must be notified to the receiving side. Thus, it is not desirable to notify the receiving side of a large amount of rearrangement information because it causes a reduction in transmission efficiency. Therefore, when transmitting a plurality of consecutive symbols in a frame, the average power of each transmission spectrum may be calculated within the frame, and rearrangement may be performed based on the calculated average power. By performing such control, an optimal rearrangement cannot be performed for each symbol, but a spectrum having an average high power in a frame can be transmitted in a propagation path where higher received power can be obtained. As compared with the case where no replacement is performed, good reception characteristics can be obtained, and the amount of rearrangement information to be notified to the reception side can be greatly reduced.

  Here, the structure of the terminal device in this embodiment is shown in FIG. As shown in FIG. 2, the terminal apparatus in this embodiment includes an encoding unit 100, a modulation unit 101, an S / P conversion unit 102, a DFT unit 103, a rearrangement determination unit 104, and a spectrum interleaving unit 105 that performs spectrum arrangement conversion. , Subcarrier mapping unit 106, IFFT unit 107, P / S conversion unit 108, CP insertion unit 109, D / A conversion unit 110, radio unit 111, transmission antenna unit 112, reception antenna unit 113, radio unit 114, A / A D conversion unit 115 and a reception unit 116 are included.

  In this terminal apparatus, first, error correction coding of transmission data is performed in the encoder 100, and modulation is performed in the modulator 101. Next, the modulated transmission signal is subjected to serial / parallel conversion in the S / P conversion unit 102 and then converted into a frequency domain signal in the DFT unit 103. The signal thus converted into the frequency domain signal is sent to the rearrangement determining unit 104 and the spectrum interleaving unit 105.

  Reordering determination section 104 calculates the power of each spectrum, and based on the calculated power and the mapping information (information indicating which subcarriers may be used) and reception level information notified from the receiving side. Rearrangement information is generated. As described above, the power of each spectrum at this time may be calculated for each symbol, but may be averaged within a frame in order to reduce information to be notified to the receiving side. In the present embodiment, the rearrangement determination unit 104 generates rearrangement information so that a spectrum having high power is transmitted on a propagation path from which high received power is obtained.

  The rearrangement information generated in the rearrangement determination unit 104 is sent to the spectrum interleaving unit 105, and based on this rearrangement information, the output signal of the DFT unit 103 is interleaved. In addition, since the rearrangement information needs to be notified to the reception side, it is transmitted together with other control information (information indicating the modulation method and the like). However, control information such as rearrangement information is not subjected to spectrum interleaving according to the present invention.

  The signal subjected to spectrum interleaving in spectrum interleaving section 105 is then mapped to subcarriers used for transmission in subcarrier mapping section 106. The mapping at this time is performed based on the mapping information notified from the base station apparatus, and zeros are inserted into subcarriers that are not used for transmission. In the present embodiment, a Localized arrangement as shown in FIG. 1 is described as this mapping, but the present invention is not limited to this, and a Distributed arrangement may be used.

  The transmission signal mapped on the subcarrier used for transmission in subcarrier mapping section 106 is then input to IFFT section 107 and converted from a frequency domain signal to a time domain signal. Then, the CP is inserted in the CP insertion unit 109 via the P / S conversion unit 108, converted into an analog signal in the D / A conversion unit 110, and then up-converted into a radio frequency band signal in the radio unit 111. Are transmitted from the transmission antenna unit 112.

  By adopting such a terminal device configuration, it is possible to perform interleaving in consideration of the propagation path condition and the transmission spectrum so that the transmission spectrum having a higher transmission power is allocated to subcarriers that can obtain higher reception power in order. Thus, it is possible to transmit a signal capable of obtaining a better error rate characteristic compared to the case where no interleaving is performed.

  Next, the configuration of the base station apparatus in the present embodiment is shown in FIG. As shown in FIG. 3, the base station apparatus in this embodiment includes an antenna unit 200, a radio unit 201, an A / D conversion unit 202, a synchronization unit 203, a CP removal unit 204, an S / P conversion unit 205, and an FFT unit 206. , Subcarrier demapping unit 207, equalization unit 208, spectrum deinterleaving unit 209 for restoring the spectrum arrangement, IDFT unit 210, demodulation / error correction decoding unit 211, scheduling unit 212, transmission unit 213, D / A conversion unit 214, a radio unit 215, and an antenna unit 216.

  In this base station apparatus, a signal transmitted from the terminal apparatus shown in FIG. 1 is received by the antenna unit 200, and the received signal is converted into a frequency that can be A / D converted by the radio unit 201, and then A / The signal is converted into a digital signal by the D conversion unit 202. Next, symbol synchronization is established by the synchronization unit 203, and after the CP is removed for each symbol by the CP removal unit 204, the time domain signal is converted to a frequency domain signal by the FFT unit 206 via the S / P conversion unit 205. Converted to a signal.

  Since the output of the FFT unit 206 is obtained by frequency-division multiplexing signals transmitted from a plurality of terminals, the terminal device in the subcarrier demapping unit 207 is based on the mapping information determined in advance by the scheduling unit 212. After the used subcarriers for each terminal are grouped, equalization section 208 performs equalization processing in the frequency domain for the received subcarriers grouped for each terminal apparatus.

  The output signal of equalization section 208 is sent to spectrum deinterleaving section 209, and spectrum deinterleaving is performed based on rearrangement information decoded together with other control information prior to data. By this deinterleaving, the spectrum is returned to the spectrum arrangement before being interleaved on the transmission side, and the output signal of the spectrum deinterleaving unit 209 is converted from the frequency domain to the time domain signal in the IDFT unit 210.

  Then, in the demodulation / error correction decoding unit 211, transmission data for each terminal device is reproduced. Also, the reception level measurement signal transmitted together with the transmission data signal from the terminal device is sent from the FFT unit 206 to the scheduling unit 212, and the scheduling unit 212 performs scheduling considering the propagation status of each terminal (subcarrier mapping information). Used for determination).

  The mapping information determined by the scheduling unit 212 is modulated by the transmission unit 213, transmitted through the D / A unit 214, the radio unit 215, and the like, and then transmitted from the antenna unit 216 to each terminal. This mapping information is used for transmission on the terminal side after the next frame. In addition, each terminal is also notified of information related to the reception level of the subcarrier (propagation path) that each terminal determines to use in the scheduling unit 212. Spectrum interleaving is performed on the terminal side based on this information and the power of the transmission spectrum.

  With such a base station apparatus configuration, the terminal apparatus shown in FIG. 2 can receive and correctly demodulate a spectrum-interleaved signal.

  Here, in the present embodiment, as shown in FIG. 1, rearrangement is performed on all spectra in consideration of the power of each spectrum and the propagation path condition (all spectra are subject to rearrangement). ) However, different from this, only the top few spectrums having high power may be the target of rearrangement. In this case, rearrangement is performed between the target spectra in consideration of the power of each spectrum and the propagation path condition. Also, interleaving may be performed such that only the spectrum having the highest power and the spectrum having the lowest power are switched in consideration of the propagation path condition. Thus, by limiting the number of spectra to be rearranged, the amount of rearrangement information notified to the receiving side can be reduced.

  As described above, according to the radio communication apparatus according to the present embodiment, spectrum interleaving is performed in consideration of the power of each spectrum and the propagation path condition. For example, a spectrum having high power is received power. As a result, it is possible to reduce the probability of transmission on a propagation path with a drop in the frequency, so that it is possible to obtain good reception characteristics (error rate characteristics). Here, an example is shown in which the power of each spectrum is calculated and rearrangement is performed according to the power. However, the present invention is not limited thereto, and rearrangement may be determined based on the envelope and size of each spectrum.

(Second Embodiment)
By performing the spectrum interleaving shown in the first embodiment, it becomes possible to allocate a transmission spectrum having a high transmission power to a subcarrier from which a higher reception power can be obtained, so that a good error rate characteristic can be obtained. However, since the spectrums are rearranged, the rearrangement information notified to the receiving side increases. Therefore, in the present embodiment, by grouping several spectra together and performing interleaving in units of groups, it is possible to obtain a better error rate characteristic than when no interleaving is performed with a small amount of rearrangement information. The possible methods are shown.

  A conceptual diagram of group-unit spectral interleaving according to this embodiment is shown in FIG. However, the left side of FIG. 4 is the same as the left side of FIG. 1 and shows an example in which two spectra are grouped. Here, it is assumed that interleaving is performed so that a spectrum group having a higher average power is transmitted through a propagation path from which higher received power is obtained.

  As shown in FIG. 4, in the interleaving according to the present embodiment, the arrangement of the spectrum in the group is not changed, and the rearrangement is performed in group units in consideration of the average power of the group and the propagation path condition. For example, in FIG. 1, since the groups of f5 and f6 have the highest power, they are rearranged so as to be transmitted in the round 1 and round 3 propagation paths where the highest average received power is obtained. Further, the group of f1 and f2 having the second highest power is transmitted through the round 5 and round 2 propagation paths where the second highest average received power is obtained. In the first embodiment, the group of f7 and f8 is rearranged into the circle 4 and the f8 is rearranged into the circle 7. In this embodiment, the f7 is a circle 7 while maintaining the arrangement in the group. F8 is assigned to circle 4.

  By performing interleaving in units of groups in this way, the error rate characteristics are slightly degraded because flexible rearrangement cannot be performed as compared with the first embodiment, but the error is better than when interleaving is not performed. Rate characteristics are obtained, and the amount of rearrangement information notified to the receiving side can be reduced. Furthermore, when performing grouping according to the present embodiment, it is possible to limit the number of groups to be interleaved as shown in the first embodiment.

  A terminal apparatus that performs such group-unit spectrum interleaving can be realized with the configuration shown in FIG. However, the rearrangement determination unit 104 calculates the average power of each spectrum group, and generates rearrangement information for each group in consideration of the calculated average power of each group and the propagation path status notified from the reception side. The Further, spectrum interleaving section 105 performs group unit interleaving in accordance with the group unit rearrangement information generated by rearrangement determination section 104.

  The base station apparatus in this embodiment can also be realized with the configuration shown in FIG. However, deinterleaving in the spectrum deinterleaving unit 209 is performed in units of groups. In this case, information regarding the reception level of the subcarrier (propagation path) determined to be used by each terminal in the scheduling unit 212 may be reported to each terminal after grouping. With the device configuration of such a terminal and base station, signals subjected to spectrum interleaving in units of groups can be transmitted and received and demodulated correctly.

  Furthermore, it is good also as a structure which can set the number of spectra which comprise one group to a different value for every terminal. This is because the PAPR characteristic deteriorates when there are a large number of groups that perform interleaving. For example, the signal may be distorted by the nonlinear amplifier, for example, the terminal is located at a point away from the base station and requires high transmission power. When the frequency becomes high, the number of spectra constituting the group is increased to reduce the number of groups, thereby suppressing the deterioration of the PAPR characteristics and not being affected by the distortion caused by the nonlinear amplifier. The configuration of such a terminal device is shown in FIG.

  As shown in FIG. 5, the terminal device for performing spectrum interleaving in units of groups by adaptively controlling the number of spectrums constituting a group has an intra-group spectrum number determination unit 117 added to the terminal device shown in FIG. It has a configuration. Information regarding the level of the received signal (signal transmitted from the base station) measured by the receiving unit 116 is sent to the in-group spectrum number determining unit 117, and the number of intra-group spectra is determined based on the received level. .

  At this time, when the measured reception level is high, it is determined that the terminal is close to the base station and the transmission power of the terminal is not so much required, and the number of spectra constituting the group is set to be small. On the other hand, when the measured reception level is low, it is determined that a high transmission power is necessary at the terminal far from the base station, and the number of spectra constituting the group is increased so as to obtain a low PAPR characteristic. By performing such control in the in-group spectrum number determination unit 117, spectrum grouping according to the position of the terminal and interleaving in units of groups can be performed.

  Information regarding the number of spectra constituting the group determined in this way is sent to the encoding unit 100 together with control information such as rearrangement information, and is subjected to processing such as encoding, and is notified to the receiving side. On the receiving side, according to the notified rearrangement information and information on the number of in-group spectra, it is possible to return to the same spectrum arrangement as that of the signal before interleaving on the transmitting side and perform demodulation correctly.

  In the present embodiment, an example in which the number of spectra constituting a group is changed according to the received power of a signal transmitted from the base station (distance from the base station) is shown, but the present invention is not limited thereto, and the terminal has low power consumption. When the mode is set, control for setting a large number of spectra constituting the group may be performed. Moreover, it is good also as a structure which determines the number of spectrum which comprises a group by the base station side, and notifies to a terminal.

  As described above, according to the wireless communication apparatus of this embodiment, spectrum interleaving is performed in units of groups in consideration of the average power of each group and the propagation path conditions. Therefore, when such interleaving is not performed. As a result, it is possible to obtain better error rate characteristics as compared with the above, and to reduce the amount of rearrangement information to be notified to the communication destination wireless communication apparatus.

(Third embodiment)
In the second embodiment, a configuration has been described in which several spectra are grouped and interleaved in units of groups. In the present embodiment, an example in which all transmission spectra are handled as a group will be described. Since the arrangement of the spectra cannot be changed within the group, when the entire transmission spectrum is handled as a group in this way, the spectrum is shifted according to the propagation path condition.

  This shift is, for example, a process of shifting laterally while maintaining the relationship between adjacent spectra so that the spectrum having the highest power is transmitted on the propagation path received with the highest received power. By performing such control, it is possible to obtain better error rate characteristics while maintaining the same PAPR characteristics as SC-FDMA signals that do not perform spectrum interleaving or shifting at all.

  An outline of this spectral shift is shown in FIG. The left side of FIG. 6 is the same as the left side of FIGS. When the spectrum shift according to the present embodiment is applied in the case of the propagation path condition and spectrum as shown on the left side of FIG. 6, the spectrum of f5 having the highest power is the round 1 propagation path where the highest received power is obtained. A process of shifting to the left by two subcarriers is performed so as to be transmitted. However, at this time, f1 and f2 are shifted to the place where f7 and f8 are arranged while maintaining the order, and the spectrum is arranged as shown on the right side of FIG.

  In this way, by shifting the entire transmission spectrum as a group, it is possible to control so that the spectrum having the highest received power is transmitted on the propagation path where the highest received power can be obtained. Therefore, the continuity of the original spectrum can be maintained and the deterioration of the PAPR characteristic can be prevented.

  Further, since only the shift amount needs to be notified to the receiving side, the amount of information related to rearrangement can be greatly reduced. Further, in the present embodiment, an example is shown in which the spectrum having the highest power is shifted so that the spectrum having the highest received power is transmitted on the propagation path where the highest received power is obtained. However, the same effect can also be obtained when shifting is performed so that the signal is transmitted through a propagation path with the lowest received power.

  A terminal device that performs such a shift of the spectrum can be realized by the configuration shown in FIG. However, the number of transmission spectra is set as the number of spectra in the group, and the spectrum interleaving unit 105 performs the above-described spectrum shift. As described in the second embodiment, the control for performing the spectrum shift according to the present embodiment is effective in the terminal having a particularly high transmission power, and the switching between the interleaving according to the first and second embodiments is performed by each terminal. It can be done according to the situation.

  As described above, according to the wireless communication device of the present embodiment, the spectrum is shifted in consideration of the power of each spectrum and the propagation path condition. For example, the spectrum having the highest power is set to the highest power. By transmitting on the propagation path obtained, it is possible to obtain a better error rate characteristic than when no shift is performed. In addition, since the arrangement of adjacent spectra is maintained, the continuity of the original spectrum can be maintained and the PAPR characteristics can be prevented from being deteriorated. Furthermore, it is possible to reduce the information amount of the rearrangement information notified to the communication destination wireless communication apparatus.

  Here, FIG. 7 shows an example of error rate characteristics when spectrum interleaving or shifting is performed according to the first, second, and third embodiments. However, this is a characteristic when the number of DFT points (subcarriers) used is 16 and the delay dispersion of the propagation path is 300 ns. The characteristics of the second embodiment are those when the number of spectra constituting the group is four. From FIG. 7, it can be seen that better error rate characteristics can be obtained when any of the methods is used than when the spectrum is not interleaved or shifted.

  The present invention is not limited to the above embodiment, and can be implemented with various modifications. Further, the present invention is not limited to the above-described embodiment, and can be appropriately changed within a range in which the effects of the present invention are exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

It is a conceptual diagram of spectrum interleaving according to the first embodiment of the present invention. It is a block diagram which shows the structure of the terminal device which concerns on 1st Embodiment. It is a block diagram which shows the structure of the base station apparatus which concerns on 1st Embodiment. It is a conceptual diagram of spectrum interleaving according to the second embodiment of the present invention. It is a block diagram which shows the structure of the terminal device which concerns on 2nd Embodiment. It is a conceptual diagram of the spectrum shift which concerns on the 3rd Embodiment of this invention. It is a figure which shows an example of the error rate characteristic at the time of performing the interleaving or the shift of the spectrum by the 1st, 2nd, 3rd embodiment of this invention. It is a block diagram which shows the structure of the terminal device at the time of using SC-FDMA system for uplink transmission. It is a block diagram which shows the structure of the base station apparatus which receives the signal transmitted from the terminal device of FIG.

Explanation of symbols

100 Code Unit 101 Modulation Unit 102 S / P Conversion Unit 103 DFT Unit 104 Rearrangement Determination Unit 105 Spectrum Interleaving Unit 106 Subcarrier Mapping Unit 107 IFFT Unit 108 P / S Conversion Unit 109 CP Insertion Unit 110 D / A Conversion Unit 111 Radio Unit 112 transmission antenna unit 113 reception antenna unit 114 radio unit 115 A / D conversion unit 116 reception unit 117 intra-group spectrum number determination unit 200 antenna unit 201 radio unit 202 A / D conversion unit 203 synchronization unit 204 CP removal unit 205 S / P conversion unit 206 FFT unit 207 Subcarrier demapping unit 208 Equalization unit 209 Spectrum deinterleaving unit 210 IDFT unit 211 Demodulation / error correction decoding unit 212 Scheduling unit 213 Transmission unit 214 D / A conversion unit 215 Radio unit 216 Antenna unit

Claims (12)

A wireless communication device that converts transmission data from a signal in the time domain to a signal in the frequency domain, assigns the spectrum of the converted signal to a subcarrier, and performs transmission.
A reordering determination unit that divides the spectrum of the signal converted into the frequency domain signal into a group composed of one or more adjacent spectra, and determines reordering information of the group in consideration of a propagation path condition; ,
A spectrum interleaving unit that performs interleaving of the spectrum of the group unit based on the rearrangement information determined in the rearrangement determination unit ,
The rearrangement determination unit calculates an average power of a spectrum constituting each group, and determines the rearrangement information in consideration of the calculated average power of each group and a propagation path condition. Wireless communication device. The wireless communication apparatus according to claim 1, wherein the rearrangement determination unit calculates an average power of each group in a transmission frame and uses the average power for determination of the rearrangement information. The radio communication apparatus according to claim 2, wherein the rearrangement determination unit determines the rearrangement information for transmitting the group of the spectrum having high power on a subcarrier having a better propagation path condition. An intra-group spectrum number determination unit for determining the number of spectra constituting the group;
4. The wireless communication apparatus according to claim 3, wherein the number of spectrums constituting the group is changed according to transmission power or a distance from a communication destination wireless communication apparatus. 5. The radio according to claim 4, wherein the in-group spectrum number determination unit increases the number of spectrums constituting the group when the transmission power is high or the distance to the communication destination radio communication apparatus is long. Communication device. The wireless communication apparatus according to claim 1, wherein the rearrangement determination unit limits the number of groups to be rearranged. A wireless communication device that converts transmission data from a signal in the time domain to a signal in the frequency domain, assigns the spectrum of the converted signal to a subcarrier, and performs transmission.
Dividing the spectrum of the signal converted into the frequency domain signal into a group composed of one or more adjacent spectra, and a reordering determination unit for determining reordering information of the group;
A spectrum interleaving unit that performs interleaving of the spectrum of the group unit based on the rearrangement information determined in the rearrangement determination unit,
The rearrangement determination unit determines the rearrangement information to be shifted so that the number of the groups is 1, and spectrum continuity is maintained. 8. The radio according to claim 7, wherein the rearrangement determination unit calculates the average power of each spectrum, and determines the rearrangement information in consideration of the calculated average power of each spectrum and a propagation path condition. Communication device. The radio communication apparatus according to claim 8, wherein the rearrangement determination unit calculates an average power of each spectrum in a transmission frame and uses the average power for determination of the rearrangement information. The radio communication apparatus according to claim 9, wherein the rearrangement determination unit determines the rearrangement information for transmitting a spectrum having the highest power on a subcarrier having the best propagation path condition. A wireless transmission device that converts transmission data from a signal in the time domain to a signal in the frequency domain, assigns the spectrum of the converted signal to a subcarrier, and performs transmission;
A wireless communication system configured to receive a signal transmitted from the wireless transmission device and convert the received signal from a time domain signal to a frequency domain signal,
The radio transmission apparatus divides a spectrum of a signal converted into a frequency domain signal into a group composed of one or more adjacent spectra, and determines rearrangement information of the group in consideration of a propagation path situation And interleaving the spectrum of the group unit based on the rearrangement information,
The radio reception device performs spectrum deinterleaving based on the rearrangement information used in the radio transmission device to restore the spectrum to the original arrangement,
The radio transmitting apparatus calculates an average power of a spectrum constituting each group, and determines the rearrangement information in consideration of the calculated average power of each group and a propagation path condition. Communications system. A wireless transmission device that converts transmission data from a signal in the time domain to a signal in the frequency domain, assigns the spectrum of the converted signal to a subcarrier, and performs transmission;
A wireless communication system configured to receive a signal transmitted from the wireless transmission device and convert the received signal from a time domain signal to a frequency domain signal,
The radio transmission apparatus divides a spectrum of a signal converted into a frequency domain signal into a group composed of one or more adjacent spectra, determines rearrangement information of the group, and based on the rearrangement information To interleave the spectrum in units of groups,
The radio reception device performs spectrum deinterleaving based on the rearrangement information used in the radio transmission device to restore the spectrum to the original arrangement,
The radio communication apparatus according to claim 1, wherein the number of the groups is set to 1, and the rearrangement information to be shifted to maintain spectrum continuity is determined.

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