JP2013236302A - Mobile station device, base station device, transmission method, and wireless communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve excellent throughput of an entire cell in uplink of wireless communication.SOLUTION: The mobile station device for transmitting a data signal and a reference signal includes a frequency filtering part that filters the data signal and the reference signal, in which a roll-off rate of the filter is specified by a constant selected from two or more constants.

Description

  The present invention relates to a mobile station apparatus, a base station apparatus, a transmission method, and a radio communication system.

In communication on the second generation mobile phone system GSM (registered trademark) (Global System for Mobile communications) and PDC (Personal Digital Cellular) uplink (communication line from mobile station device to base station device) Transmission is performed by applying a Nyquist filter so that continuous transmission signals do not interfere with each other. Here, when an ideal filter (a filter having a rectangular transfer function with a constant ratio of input signal to output signal in a certain frequency region) is used as the Nyquist filter, the impulse response continues indefinitely.
For this reason, when trying to realize the above-described filter with a digital filter created with a finite number of taps, interference between transmission signals (intersymbol interference) occurs. Therefore, in order to suppress the influence when realized with a finite number of taps, a mobile station apparatus generally uses a roll-off filter as a Nyquist filter. Since the roll-off filter has a smoother transfer function near the cutoff frequency than the ideal rectangular filter, the roll-off filter has the effect of suppressing the PAPR (Peak-to-Average Power Ratio) of the transmitted signal. There is also.
By using a roll-off filter, intersymbol interference can be suppressed even when a digital filter created with a finite number of taps is used. However, the frequency bandwidth used by each mobile station device depends on the roll-off rate, and the signal bandwidth Wider than.
Therefore, when multiplexing the transmission signal of each mobile station apparatus in the frequency domain, it is necessary to perform transmission so that the signal after application of the roll-off filter does not interfere with the signals of other mobile station apparatuses. In other words, it is necessary to set a band called a guard band between the transmission signals of each mobile station apparatus. For this reason, in wireless communication in which a roll-off filter is applied to the transmission signal, there is a problem that the frequency utilization efficiency decreases. there were.

  By the way, in the communication standard called LTE (Long Term Evolution) that 3GPP (Third Generation Partnership Project) has standardized as a mobile phone system of the 3.9th generation or later, the LTE downlink (base station) OFDMA (Orthogonal Frequency Division Multiple Access) is employed in communication on a communication line from a device to a mobile station device, whereas SC-FDMA (Single-Link) is used in LTE uplink communication. Carrier Frequency Division Multiple Access (single wave frequency division multiple access) is employed.

  In SC-FDMA, each mobile station apparatus (User Equipment; sometimes referred to as “UE” or “terminal”) converts a transmission modulation symbol into a discrete frequency spectrum by a Discrete Fourier Transform (DFT). , A discrete frequency notified (assigned) from a base station apparatus (enhanced Node B; “eNB” or “control station apparatus”) (the minimum unit of assignment is an RB (Resource Block)) Although the resource block RB is composed of a plurality of discrete frequencies, the discrete frequency spectrum is arranged in the resource block RB, and zeros are inserted in the discrete frequencies where the spectrum is not arranged. Next, each mobile station apparatus generates a time-domain signal waveform by IFFT (Inverse Fast Fourier Transform) for the output of the DFT, and then D / A (Digital-to-Analog; digital / analog) ) Transmission is performed after conversion and frequency conversion to the carrier frequency. At this time, in SC-FDMA, it is not necessary to provide a guard band as in GSM (registered trademark) and PDC, and adjacent mobile frequencies can use adjacent discrete frequencies. can do.

In SC-FDMA, the periodicity of the discrete Fourier transform can be used by generating a single carrier signal by the same signal generation method as OFDMA, so that an ideal filter can be applied to the signal. That is, since only the ideal filter is convoluted with respect to the transmission modulation symbol, signal transmission with a PAPR lower than that of OFDM can be performed. However, since the ideal filter is applied, there is a problem that the PAPR is deteriorated as compared with the case where the roll-off filter is applied.
Therefore, Patent Document 1 describes that the mobile station apparatus performs transmission with a low PAPR by applying a roll-off filter with a roll-off rate notified from the base station apparatus.
Further, in Non-Patent Document 1, studies are being made to apply a roll-off filter to SC-FDMA to suppress PAPR. That is, in Non-Patent Document 1, since the band used by each mobile station apparatus is widened by applying a roll-off filter, it interferes with a transmission signal of an adjacent mobile station, but the interference is repeatedly processed by the base station apparatus. It is proposed to separate by doing.

JP 2009-246502 A

S. Okuyama, Kazuki Takeda, and F. Adachi, "Frequency-domain Iterative MUI Cancellation for Uplink SC-FDMA Using Frequency-domain Filtering," 2010 IEEE 72nd Vehicular Technology Conference (VTC-Fall), Ottawa, Canada, 6-9 Sept. 2010.

  In the method of Patent Document 1, in addition to the need to notify the roll-off rate for specifying the roll-off filter, in order to prevent leakage to adjacent frequencies, the band is limited by lowering the transmission symbol rate, Even after the roll-off filter is applied, leakage of the frequency to the adjacent frequency is suppressed. Therefore, in order to achieve low PAPR, there has been a problem that throughput (throughput; effective speed) is deteriorated. In Non-Patent Document 1, since it is assumed that all mobile station apparatuses apply a roll-off filter to SC-FDMA, signal separation processing at the reception part of the base station apparatus becomes complicated. That is, when SIC (Successive Interference Cancellation) is performed at the reception part of the base station apparatus in an environment where all RBs are used by many mobile stations, SIC including all mobile station apparatuses is performed. become. For this reason, there is a problem that the complexity of the apparatus and processing delay are problems, and it is difficult to perform reception processing considering all mobile station apparatuses.

  In view of the above points, an object of the present invention is to provide a mobile station apparatus, a base station apparatus, a transmission method, and a wireless communication system that have solved the drawbacks of the conventional techniques. It is as follows.

(1) The present invention has been made to solve the above-described problem, and the mobile station apparatus of the present invention is a mobile station apparatus that transmits a data signal and a reference signal, and the mobile station apparatus transmits the data signal. And a frequency filter section for filtering the reference signal, wherein the roll-off rate of the filter is determined by one constant selected from two or more constants.
(2) Moreover, the mobile station apparatus of this invention is the above-mentioned mobile station apparatus, Comprising: It has the constant determination part which selects the constant which determines the said roll-off rate, It is characterized by the above-mentioned.
(3) Moreover, the mobile station apparatus of the present invention is the above-described mobile station apparatus, wherein the two or more constants have a zero output frequency within a range of an allocated frequency band of the data signal and the reference signal. And a constant set outside the range.
(4) Moreover, the mobile station apparatus of the present invention is the above-described mobile station apparatus, wherein the zero output frequency set outside the frequency band assigned to the data signal and the reference signal is other mobile station apparatus. The data signal and the reference signal are set within a frequency band range.
(5) Moreover, the mobile station apparatus of the present invention is the above-described mobile station apparatus, wherein the constant is a roll-off filter including a portion having a flat pass characteristic and a gentle curved portion near the cutoff frequency. It is characterized by the roll-off rate.
(6) Moreover, the mobile station apparatus of the present invention is the mobile station apparatus described above, and when the roll-off rate is zero, the zero output frequency is within the range of the frequency band assigned to the data signal and the reference signal. The passing characteristic is characterized by comprising only a flat portion.
(7) Moreover, the mobile station apparatus of the present invention is the above-described mobile station apparatus, wherein the selected constant is different for each of the data signal and the reference signal.
(8) Further, the mobile station apparatus of the present invention is the above-described mobile station apparatus, wherein a flat portion of a pass characteristic of the filter is wide for a reference signal and narrow for a data signal. And
(9) Moreover, the mobile station apparatus of this invention is the above-mentioned mobile station apparatus, The said roll-off rate is large with respect to a reference signal, It is characterized by the above-mentioned.
(10) Further, the mobile station apparatus of the present invention is the above-described mobile station apparatus, wherein the constant determining unit determines the constant according to information shared with a base station apparatus that is a transmission destination of the data signal and the reference signal. It is characterized by defining.
(11) Moreover, the mobile station apparatus of this invention is the above-mentioned mobile station apparatus, Comprising: The information shared with the said base station apparatus is a power headroom, It is characterized by the above-mentioned.
(12) The present invention has been made to solve the above-described problems, and the base station apparatus of the present invention is a data signal and a reference signal transmitted from each of a plurality of mobile stations, and is a single mobile station apparatus. The first state in which the data signal and reference signal transmitted by the mobile station exceed the allocated frequency band and also occupy the allocated frequency band of another mobile station apparatus, and the data transmitted by another mobile station apparatus One base station apparatus that receives a signal in which a signal and a reference signal are mixed with a second state in which the reference signal is in the assigned frequency band, the first state with respect to the received signal An iterative processing unit that separates signals by performing iterative processing is provided.
(13) The present invention has been made to solve the above-described problem, and a radio communication system of the present invention is a radio communication system including a base station apparatus and a plurality of mobile station apparatuses, and the plurality of mobile station apparatuses The transmission unit includes a frequency filter unit that determines whether to apply frequency filtering to the data signal and the reference signal for each mobile station apparatus.
(14) The present invention has been made to solve the above-described problem. The transmission method of the present invention includes a process of converting a time domain signal into a frequency domain signal and a process of mapping the frequency domain signal to an arbitrary frequency. And a step of filtering the frequency domain signal according to a roll-off rate specified by a roll-off rate determination unit, and a step of transmitting the frequency domain signal, wherein the frequency domain signal is arbitrarily selected. In the process of arranging at the frequency, whether or not the frequency is arranged so as to overlap with the output of the frequency filter unit of another mobile station is determined by the roll-off rate.

  According to the present invention, it is possible to improve the throughput of the entire cell in the uplink of wireless communication.

It is a schematic block diagram which shows the structure of the radio | wireless communications system common to each embodiment. It is a schematic block diagram which shows the structure of the mobile station apparatus which concerns on 1st Embodiment. FIG. 3 is a schematic block diagram illustrating a configuration of an SC-FDMA signal generation unit in FIG. 2. (A) The average energy in the frequency domain of the input signal of the frequency filter unit is shown. (B) The average energy in the frequency domain of the output signal of the frequency filter unit is shown. It is a schematic block diagram which shows the structure of a frequency filter part. (A) The frequency spectrum of the input signal to the spectrum repeater is shown. (B) The frequency spectrum of the output signal from a spectrum repetition part is shown. (C) The filter characteristic of the roll-off filter used for the filter part is shown. It is a block diagram which shows the detail of a roll-off rate determination part. It is a flowchart which shows operation | movement of the roll-off rate determination part. It is a schematic block diagram which shows the structure of the receiving part of a base station apparatus. It is a schematic block diagram which shows the structure of a SC-FDMA signal receiving part. (A) It is a figure which shows the passage characteristic of the frequency filter part of a some mobile station apparatus. (B) It is another figure which shows the passage characteristic of the frequency filter part of a some mobile station apparatus. (C) It is another figure which shows the pass characteristic of the frequency filter part of a some mobile station apparatus. It is another figure which shows the pass characteristic of the frequency filter part of a some mobile station apparatus. It is a schematic block diagram which shows the structure of a repetition process part. It is a figure explaining the process in a spectrum synthetic | combination part. It is a schematic block diagram which shows the structure of the mobile station apparatus which concerns on 2nd Embodiment. It is a block diagram which shows the detail of a roll-off rate determination part. It is a flowchart which shows operation | movement of the roll-off rate determination part. (A) shows the pass characteristic of the frequency filter unit when the input signal is a data signal. (B) shows the pass characteristic of the frequency filter unit when the input signal is DMRS. It is a schematic block diagram which shows the structure of the repetition process part in the structure of the receiving part of the base station apparatus of 3rd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described.
FIG. 1 is a schematic block diagram showing a configuration of a wireless communication system 10 according to the first embodiment of the present invention. The configuration of the wireless communication system in FIG. 1 is common to other embodiments.
The wireless communication system 10 includes a base station device 101 and mobile station devices 102-1 to 102-3. FIG. 1 shows three mobile station apparatuses, but this is an example. The mobile station apparatuses 102-1 to 102-3 have the same configuration in the outline, and hereinafter, the mobile station apparatuses 102-1 to 102-3 may be collectively referred to as “mobile station apparatus 102”. .
The plurality of mobile station apparatuses 102 includes FDMA (Frequency Division Multiple Access), CDMA (Code Division Multiple Access), MU-MIMO (Multi-User Multiple Input Multiple Output); )) Or the like, simultaneous access (simultaneous connection) to the base station apparatus 101 can be performed.

FIG. 2 is a schematic block diagram showing the configuration of the mobile station apparatus 102. The illustration and description of other known configurations of the mobile station apparatus 102 are omitted.
Although the number of transmission antennas is 1 in FIG. 2, known techniques such as transmission antenna diversity and MIMO can be applied such that the mobile station apparatus 102 includes a plurality of transmission antennas. When a plurality of transmission antennas are used, the same processing as when the number of transmission antennas is 1 is applied to each antenna port.

A sequence of data bits is input to the encoding unit 201 from an upper layer (not shown). The encoding unit 201 performs error correction encoding such as a turbo code to obtain an encoded bit sequence. The obtained encoded bit sequence is input to modulation section 202. The modulation unit 202 performs modulation to symbols such as QPSK (Quaternary Phase Shift Keying) and 16QAM (16-ary Quadrature Amplitude Modulation).
The symbol series is input to the DFT unit 203. The DFT unit 203 converts the input modulation symbol sequence into a frequency domain signal (spectrum) by applying an M-point DFT for every M symbols, and inputs the signal to the DMRS multiplexing unit 205. DMRS multiplexing section 205 time-multiplexes the frequency spectrum of the data input from DFT section 203 and the M-point DMRS sequence input from DMRS generating section 204 to form a frame. DMRS is an abbreviation for Demodulation Reference Signal. Hereinafter, the DMRS may be referred to as a “reference signal”.

The output of the DMRS multiplexing unit 205 is input to the frequency mapping unit 206. The frequency mapping unit 206 performs spectrum allocation based on the allocation information notified from the base station apparatus 101. Zeros are input to frequencies (subcarriers) for which assignment has not been performed. The output from the frequency mapping unit 206 is input to the frequency filter unit 207.
The processing in the frequency filter unit 207 will be described later.
The output of the frequency filter unit 207 is input to the SC-FDMA signal generation unit 208.

FIG. 3 is a schematic block diagram illustrating a configuration of the SC-FDMA signal generation unit 208.
In FIG. 3, the input from the frequency filter unit 207 is input to the IFFT unit 301. In IFFT section 301, N _FFT point IFFT is applied, and an input signal is converted from a frequency domain signal to a time domain signal. Here, N _FFT > M. M is the number of points of the DFT unit 203.
The output of IFFT unit 301 is input to CP adding unit 302. The CP adding unit 302 applies a process of copying a part of the rear of the time waveform, which is the output of the IFFT unit 301, and adding it to the front of the output waveform. By adding the CP, the influence of the delayed wave in the propagation path can be suppressed. The output of the CP adding unit 302 is converted from a digital signal to an analog signal by D / A conversion applied by the D / A conversion unit 303. The analog signal output from the D / A conversion unit 303 is input to the analog filter unit 304, and after analog filtering such as a low-pass filter is performed, the analog signal is input to the power amplification unit 305.

The power amplifying unit 305 amplifies the input signal to a predetermined value of power. Here, the power amplifying unit 305 receives the roll-off rate from the roll-off rate determining unit 213, and can perform power amplification considering the value of the roll-off rate.
The output of the power amplification unit 305 is input to the up-conversion unit 306, and up-conversion to the carrier frequency is performed. The output of the up-conversion unit 306 is transmitted as the output of the SC-FDMA signal generation unit 208 via the transmission antenna 209.

Next, processing in the frequency filter unit 207 will be described.
4A shows the average power spectral density in the frequency domain of the input signal of the frequency filter unit 207, and FIG. 4B shows the average power spectral density in the frequency domain of the output signal of the frequency filter unit 207. Yes. In FIGS. 4A and 4B, the center of the assigned frequency band is set to zero, and the frequency band is shown as being standardized from −1 to +1.
The frequency filter unit 207 applies a frequency filter to an input signal having a constant spectrum with an average power spectrum density as shown in FIG. 4A and a frequency band B of −1 ≦ B ≦ 1. As shown in FIG. 4B, the frequency band B of the output signal becomes −1−α ≦ B ≦ 1 + α, and the band of the original spectrum (FIG. 4A) is expanded by (1 + α) times. Generate a spectrum. At this time, although the frequency band of FIG. 4B is (1 + α) times, the PAPR of the time domain signal waveform can be made lower than the PAPR of FIG.

Next, processing performed by the frequency filter unit 207 to form an output signal having an average power spectral density as shown in FIG. 4B will be described with reference to FIG.
FIG. 5 is a schematic block diagram showing the configuration of the frequency filter unit 207.
The spectrum input from the frequency mapping unit 206 is input to the spectrum repetition unit 501 of the frequency filter unit 207.
Here, it is assumed that the signal 601 input from the frequency mapping unit 206 is represented as shown in FIG. 6A, 6B, and 6C, the horizontal axis indicates the frequency, and the vertical axis indicates the power spectral density. The allocated frequency band in this case is between the frequency x and the frequency (x + M).

In FIG. 6A, a spectrum D (k) (where 0 ≦ k ≦ M−1) of a signal 601 having a bandwidth of M subcarriers is arranged with the xth subcarrier at the head.
The spectrum repetition unit 501 generates a spectrum S (n) 602 (where 0 ≦ n ≦ N _FFT −1) in which the spectrum D (k) is repeated on the frequency axis. That is, S (n) is given by the following equation. Here, 'mod' represents a remainder operation.

Returning to FIG. 5, the spectrum repeater 501 inputs a signal in which the signal spectrum is repeated as shown in FIG.
Here, the filter generation unit 503 will be described.
The filter generation unit 503 generates a roll-off filter based on the roll-off rate input from the roll-off rate determination unit 213. For example, a roll-off filter having a filter characteristic as shown in FIG. 6C is generated for the signal shown in FIG. An example of the transfer function G (n) of the roll-off filter that multiplies the signal of the bandwidth M is shown in the following equation (2).

The transfer function G (n) of the roll-off filter expressed by Equation (2) is composed of a flat straight line portion and a cosine curve portion, and satisfies the Nyquist criterion and suppresses unnecessary sidebands. The filter of Equation (2) is called a root raised cosine filter. The filter generation unit 503 forms a filter G (n) centered on the allocated band based on the input roll-off rate, and inputs the filter G (n) to the multiplication unit 502. Hereinafter, the roll-off rate may be referred to as a “constant”.
The curve portion of the filter generated by the filter generation unit 503 is not limited to the cosine curve. The roll-off rate is a variable that determines the pass characteristics of the filter. A roll-off rate of zero means that the pass characteristics are rectangular and consist only of flat portions.
Multiplier 502 multiplies the output of spectrum repeater 501 and the output of filter generator 503 for each frequency, and inputs the multiplication result to SC-FDMA signal generator 208 as the output of frequency filter 207 (FIG. 2).
Since the spectrum output from the multiplier 502 is repeated by the spectrum repeater 501, the same spectrum (D (0)) is transmitted by the x-th subcarrier and the (x + M) -th subcarrier. Similarly, the same spectrum (D (1)) is transmitted in the (x + 1) th subcarrier and the (x + M + 1) th subcarrier.
However, when zero is input as the value of the roll-off rate α, G (n) becomes a rectangular filter, which is equivalent to performing no processing in the frequency filter unit 207.

  As described above, the frequency filter unit 207 performs processing for expanding the signal spectrum D (k) having the bandwidth of M subcarriers to a band of (1 + α) times. As a result, although the bandwidth used by the mobile station 102 is expanded, it is possible to generate a signal with a low time waveform PAPR, and thus it is possible to expand the coverage (communication area).

Next, the roll-off rate input from the roll-off rate determining unit 213 to the frequency filter unit 207 will be described.
The reception antenna 211 of the mobile station apparatus 102 receives the transmission signal from the base station apparatus 101 and inputs it to the control information acquisition unit 212. The control information acquisition unit 212 extracts control information used for uplink transmission from the input information and inputs the control information to the roll-off rate determination unit 213.
FIG. 7 is a block diagram showing details of the roll-off rate determining unit 213.
In FIG. 7, the roll-off rate information extraction unit 701 extracts control information related to the roll-off rate from the control information input from the control information acquisition unit 212, and sends the extracted control information to the roll-off rate setting unit 702. Output. Roll-off rate setting unit 702 determines a roll-off rate according to the information, and outputs this roll-off rate to frequency filter unit 207 and SC-FDMA signal generation unit 208.

FIG. 8 is a flowchart for explaining the operation of the roll-off rate determination unit 213.
In FIG. 8, the roll-off rate information extraction unit 701 acquires control information input from the control information acquisition unit 212 (step S801). The roll-off rate information extraction unit 701 extracts parameters for determining the roll-off rate from the input control information (step S802). The roll-off rate setting unit 702 sets a roll-off rate from the extracted parameters (S803). The roll-off rate setting unit 702 outputs the set roll-off rate to the frequency filter unit 207 and the SC-FDMA signal generation unit 208 (S803).

Here, the information regarding the roll-off rate may be notified directly from the base station apparatus, or only information regarding whether or not to perform frequency filtering is notified, and the roll-off rate determining unit 213 does not perform the information. May be configured such that α = 0 is input to the frequency filter unit 207, and if it is to be performed, a predetermined α value (for example, α = 0.22, 0.50, etc.) is input to the frequency filter unit 207. In addition, the roll-off rate may be determined in association with parameters of an existing LTE system.
For example, in LTE, the mobile station apparatus subtracts the transmission power necessary to achieve the reception power determined by the base station apparatus from the maximum allowable transmission power as a PH (Power Headroom) to the base station apparatus. Notify. In this case, the PH value is shared between the mobile station apparatus and the base station apparatus. Therefore, when PH is larger than a predetermined value, there is power remaining, so frequency filtering is not applied. When PH is smaller than a predetermined value, power is left free, so frequency filtering is applied. A signal with a low PAPR is generated.
When a signal with a low PAPR is generated, it is possible to perform transmission with higher power than before by the power amplifier.

Various other LTE parameters can be used.
For example, a mobile station apparatus that is generally close to the base station apparatus has a sufficient transmission power, so that the required reception power is satisfied even with a low transmission power, whereas a mobile station apparatus that is far from the base station apparatus has a path loss. Therefore, there is a high possibility that transmission is performed with an allowable maximum transmission power. Furthermore, there is a high possibility that a mobile station device far from the base station device cannot receive with the required reception power even though transmission is performed with the allowable maximum transmission power. Therefore, it is assumed that low-order modulation such as QPSK is performed. That is, it can be considered that a mobile station apparatus that performs transmission using QPSK has lower reception power than a mobile station apparatus that performs transmission using 16QAM. Therefore, the mobile station apparatus designated by the base station apparatus for QPSK transmission can simultaneously increase the transmission power by voluntarily applying frequency filtering and suppressing PAPR. In addition, in MIMO transmission, a mobile station apparatus having a low number of streams (or ranks and layers) can be set to apply frequency filtering, and the mobile station apparatus notifies the base station apparatus. Depending on the downlink received power, it may be determined whether to apply frequency filtering. By defining in this way, it is possible to determine whether or not to apply frequency filtering without notification of new control information or while entrusting to other information.

  Further, LTE-Rel. In 10 and later, a technique called carrier aggregation has been introduced that can perform transmission of a maximum of 100 MHz by transmitting a plurality of LTE bands having a maximum bandwidth of 20 MHz in parallel. Each LTE band is called a component carrier. In this embodiment, frequency filtering can be applied to each carrier component, and collective frequency filtering can be applied to all carrier components. Furthermore, it is also possible to divide a plurality of carrier components into several groups and decide whether to apply frequency filtering in each group.

  In the above description, SC-FDMA, which is a transmission method using continuous resource elements, has been described as an example, but the frequency spectrum after DFT is divided into a plurality of clusters, and each cluster is discontinuous on the frequency axis. The present invention can be applied to Clustered DFT-S-OFDM which is a transmission method to be assigned. In that case, frequency filtering may be applied to each cluster, or one frequency filtering may be applied to the entire spectrum. Furthermore, for Clustered DFT-S-OFDM composed of three or more clusters, clusters having relatively close frequencies perform collective frequency filtering, and clusters that are separated in frequency are subjected to different frequency filtering (different roles). It is also possible to adopt a configuration in which an off rate is applied.

Signals transmitted from the transmission antennas 209 of the plurality of mobile station apparatuses 102 are received by the reception antennas of the base station apparatus 101 via radio propagation paths (uplinks).
FIG. 9 is a schematic block diagram of the configuration of the reception part of the base station apparatus 101 in the present embodiment. Illustration and description of the transmission part of the base station apparatus 101 and other known configurations of the base station apparatus are omitted.
_{N r} signals receiving antennas _{901-1~901-N r} receives the present of a base station apparatus 101 is input to the SC-FDMA signal receiving unit _{902-1~902-N r,} respectively.
Hereinafter, the antennas 901-1 to 901 -N _r , the SC-FDMA signal receiving units 902-1 to 902 -N _r , and the frequency demapping units 903-1 to 903 -N _r are collectively referred to as “antenna 901”, These may be referred to as “SC-FDMA signal receiving unit 902” and “frequency demapping unit 903”, respectively.
Note that the base station apparatus 101 may have one reception antenna or a plurality of reception antennas. When the base station apparatus 101 has a plurality of reception antennas, the base station apparatus 101 can perform multi-user MIMO with a plurality of mobile station apparatuses 102. When the base station apparatus 101 has one receiving antenna, one SC-FDMA signal receiving unit 902 and frequency demapping unit 903 are provided.

FIG. 10 is a schematic diagram showing the configuration of the SC-FDMA signal receiving unit 902.
The signal input from the antenna 901 to the SC-FDMA signal receiving unit 902 can be down-converted to the baseband (base frequency band) in the down-conversion unit 1001, and then the analog filter unit 1002 performs a low-pass filter or AGC (Auto Gain Control (automatic gain control) and the like are applied. An output of the analog filter unit 1002 is input to an A / D conversion unit 1003, and A / D (Analog-to-Digital) conversion is applied to convert the output into a digital signal. The output of A / D conversion section 1003 is input to CP removal section 1004, and the CP added by the transmitter (transmission part of the mobile station apparatus) is removed. The output of the CP removal unit 1004 is input to the FFT unit 1005, and conversion to a frequency domain output signal is performed by applying FFT of N _FFT points to the time domain input signal. The output of the FFT unit 1005 is input to the frequency demapping unit 903 as the output of the SC-FDMA signal receiving unit 902.

The frequency demapping units 903-1 to 903 -N _r extract the frequencies used for communication by the predetermined mobile station apparatus 102, including the frequency band that has been expanded and used, and the received signal of the data bits is a repetitive processing unit In 904, the received signal of the reference signal is input to the channel estimation unit 905.

Here, the case of frequency allocation as shown in FIG.
In FIG. 11A, mobile station apparatuses 102-1, 102-2 and 102-3 have frequency bands of frequencies f _{1 to} f ₂ , frequency bands of frequencies f _{2 to} f ₃ and frequencies of f _{3 to} f ₄ . Each band is allocated. Furthermore, as an example, the filters of the filter unit 207 of the mobile station apparatuses 102-1 to 102-3 are ideal rectangular filters having a roll-off rate of zero and have pass characteristics (transfer functions) 1101 to 1103, respectively.
FIG. 9B shows another example. In FIG.11 (b), the filter part 207 of the mobile station apparatuses 102-1 to 102-3 has the pass characteristics 1111 to 1113, respectively. Since the frequency filter unit 207 of the mobile station apparatuses 102-1 to 102-3 uses a roll-off filter whose roll-off rate is not zero, the transfer function near the cutoff frequency (cut-off frequency) is higher than that of the ideal rectangular filter. It is gentle.
When the mobile station apparatus 102-3 is a desired mobile station apparatus, in the SC-FDMA 902-3 of the base station apparatus 101 corresponding to the mobile station apparatus 102-3, the frequency used by the mobile station apparatus 102-3 for transmission is All are extracted. Further, a part of the frequency used by the mobile station apparatus 102-3 is also used by the mobile station apparatus 102-2, which causes interference. Since this interference needs to be removed by the iterative processing unit 904 (FIG. 9), information regarding the mobile station device 102-2 is also required. That is, in addition to the frequency used by mobile station apparatus 102-3 for transmission, the frequency used by mobile station apparatus 102-2 for communication is also extracted.
Furthermore, the mobile station device 102-2 shares a frequency with the mobile station device 102-1. As a result, in order to decode the data of the mobile station device 102-3, all the frequencies used by the mobile station device 102-1, the mobile station device 102-2, and the mobile station device 102-3 are extracted, It is necessary to input to the repetition processing unit 904. Thus, the frequency demapping unit _{903-1~903-N r,} a desired mobile station apparatus, for example a frequency of the mobile station device 102-3 is used in the communication, and interference to become mobile station apparatus, for example, the mobile station apparatus The frequency 102-2 is extracted, the data bit reception signal is input to the repetition processing unit 904, and the reference signal reception signal is input to the channel estimation unit 905.

  Here, when all mobile station apparatuses 102-1 to 102-3 apply frequency filtering at a roll-off rate other than zero, and all mobile station apparatuses 102-1 to 102-3 use adjacent frequencies. Since the iterative processing unit 704 needs to perform processing in consideration of all the mobile stations 102-1 to 102-3, signal processing becomes extremely complicated and a large processing delay occurs.

  However, since all mobile station apparatuses do not necessarily apply frequency filtering with a roll-off rate other than zero, for example, even when the use frequencies of all mobile station apparatuses 102-1 to 102-3 are adjacent, The inventor has found that the iterative processing unit 904 does not have to perform processing in consideration of all the mobile station apparatuses 102-1 to 102-3. In other words, this is a state in which the frequency arrangement of each of the mobile station apparatuses 102-1 to 102-3 is, for example, as shown in FIG.

FIG.11 (c) shows the passage characteristic (transfer function) of the frequency filter part 207 of the mobile station apparatuses 102-1 to 102-3.
In FIG.11 (c), the filter of the frequency filter part 207 of the mobile station apparatuses 102-1 to 102-3 has pass characteristics 1121 to 1123, respectively. Since the filter unit 207 of the mobile station apparatus 102-3 uses a roll-off filter with a roll-off rate other than zero, the pass characteristic 1123 has a gentle transfer function near the cutoff frequency. However, the filter units 207 of the mobile station apparatuses 102-1 and 102-2 have rectangular pass characteristics 1121 and 1122 in the frequency domain because an ideal filter having a roll-off rate of zero is used.
In FIG.11 (c), since the mobile station apparatus 102-3 is applying the frequency filtering by roll-off rates other than zero, the frequency band 1123 spreads, and the pass characteristic 1122 and spectrum of the filter of the mobile station apparatus 102-2 are spread. However, since mobile station apparatus 102-1 and mobile station apparatus 102-2 do not apply frequency filtering with a roll-off rate other than zero, mobile station apparatus 102-1 and mobile station apparatus 102- 2 are in an orthogonal relationship. That is, in order to extract data of the mobile station device 102-3, only the mobile station device 102-2 needs to be considered in addition to the mobile station device 102-3. Moreover, when taking out the data of the mobile station apparatus 102-2, it is only necessary to consider only the mobile station apparatus 102-3 in addition to the mobile station apparatus 102-2.

FIG. 12 shows still another example.
12, the mobile station device 102-1 performs the transmission of data bits to the base station apparatus 101 using the resource blocks RB ₀ and RB _1. Similarly, the mobile station device 102-2 uses a resource block RB ₂ and RB _3, the mobile station device 102-3 uses a resource block RB _4.
The frequency filter unit 207 of the mobile station apparatuses 102-1 and 102-3 has rectangular pass characteristics 1201 and 1203 in the frequency domain because an ideal filter with a roll-off rate of zero is used. Since the frequency filter unit 207 of the mobile station apparatus 102-2 uses a roll-off filter with a roll-off rate other than zero, the transfer function near the cutoff frequency is gentle. However, the frequency at which the filter output becomes zero falls within the resource blocks RB ₂ and RB ₃ . Here, the frequency at which the filter output is 0 is hereinafter referred to as a zero output frequency. For the sake of simplicity, the frequency at which the filter output is 0 is referred to as the zero output frequency. However, the frequency is not necessarily 0, and any value may be used as long as it is a predetermined value smaller than the output before the filter application. There may be.
Therefore, in the case of frequency allocation and filter selection of the filter unit 207 shown in FIG. 12, all three mobile station apparatuses 102 are in an orthogonal relationship. It will be good. That is, in this case, iterative processing is not always necessary.

Thus, by determining whether to apply frequency filtering for each mobile station apparatus 102 (whether the roll-off rate is other than zero), the signal at the reception part of the base station apparatus 101 is determined. Processing complexity and processing delay can be greatly reduced.
However, when the iterative processing unit 904 does not remove interference from other mobile station apparatuses, only the frequency used by the desired mobile station apparatus 102 for communication may be extracted. Also, in the case of providing a plurality of receiving antennas, a desired movement can be achieved even when interference from other mobile station apparatuses is suppressed by multiplying a MIMO weight such as a ZF weight or an MMSE weight accompanied by an inverse matrix operation. Only the frequency used by the station apparatus 102 for communication may be extracted.

Returning to FIG. 9, the channel estimation unit 905, using the received reference signals input from the frequency demapping unit _{903-1~903-N r} (DMRS), the desired mobile station apparatus 102, for example, mobile station apparatus 102 -3 performs channel estimation of the frequency used for communication and channel estimation at the transmission frequency of the mobile station apparatus that interferes, for example, the mobile station apparatus 102-2, and the channel estimation value of each mobile station apparatus 102 is repeatedly transmitted to the processing unit 904. input. Normally, since frequency filtering is also applied to the DMRS, the channel estimation unit 905 performs channel estimation using the DMRS to which frequency filtering is applied.

The iterative processing unit 904 uses the received data signal input from the frequency demapping units 903-1 to 903-N _r and the channel estimation value of each mobile station apparatus 102 input from the channel estimation unit 905 to generate a desired value. The data bits transmitted by the mobile station device, for example, the mobile station device 102-3 are estimated and output as data bits.

FIG. 13 is a schematic block diagram showing the configuration of the iterative processing unit 904.
In the configuration of FIG. 13, the reception part of the base station apparatus 101 detects a data bit sequence transmitted by a desired mobile station apparatus, for example, the mobile station apparatus 102-3. However, the receiving part of the base station apparatus 101 also has a separate iterative processing unit (not shown) for decoding signals of other mobile station apparatuses, for example, the mobile station apparatuses 102-1 and 102-2. Yes.
13, a signal input from the frequency demapping unit _{903-1~903-N r} are input into the cancellation portion _{1301-1~1301-N r.} The cancellation unit _{1301-1~1301-N r,} the input from the reception replica generation unit 1311, and subtracted from the input from the frequency demapping unit _{903-1~903-N r,} and inputs to the equalizer 1302. However, in the first iteration described below, the output of the reception replica generation unit 1311 is set to zero so that nothing is canceled.
The equalization unit 1302 with respect to the signal input from the cancel unit _{1301-1~1301-N r,} by multiplying the weights input from the weight generation unit 1303 performs a reception antenna synthesis.

Here, the weight generated by the weight generation unit 1303 is generated from the channel estimation value input from the channel estimation unit 905 (FIG. 9) and the symbol replica generated by the symbol replica generation unit 1309. However, when removing interference signals from other mobile station apparatuses, weights are generated in consideration of channel estimation values and symbol replicas corresponding to the respective mobile station apparatuses. That is, the equalization unit 1302 performs equalization by multiplying the received signal by a weight for each subcarrier (sometimes referred to as “resource element” or “discrete frequency spectrum”) and performing reception antenna synthesis, The obtained signal for each subcarrier is output to spectrum synthesis section 1304.
Also, since the channel estimation value is a channel estimation value when a combination of both the transmission filter and the actual transmission path is regarded as a channel, equalization is performed when the transmission filter is a root raised cosine filter. Thus, a raised cosine filter is formed by transmission and reception.
Here, when the spectrum of another mobile station device, for example, the mobile station device 102-2, is multiplexed in at least a part of the spectrum, a weight that separates these spectra is generated, and this weight is set. Multiply.
In spectrum combining section 1304, when the band is spread (1 + α) times in frequency filter section 207 in the transmission part of mobile station apparatus 102, since substantially the same spectrum is received by a plurality of subcarriers, Synthesize the spectrum.
This synthesis point will be described below.

FIG. 14 shows an output 1401 of the equalization unit 1302 when frequency filtering using a roll-off filter is performed.
In FIG. 14, normalization is performed by setting the zero output frequency of the low band to “0”. M indicates the allocated frequency bandwidth in units of subcarriers.
Regarding the output 1401 of the equalizing unit 1302, the reception spectrum R (m) of the m-th subcarrier and the reception spectrum R (m + M) of the (m + M) th subcarrier have different phases but have the same phase. Therefore, spectrum combining section 1304 combines received spectrum R (m) and received spectrum R (m + M) shown in FIG.
However, what is synthesized is a received spectrum of 0 ≦ m ≦ αM and M ≦ m ≦ (1 + α) M where the same spectrum is transmitted.
By performing reception spectrum synthesis, a reception spectrum of (1 + α) M points becomes a reception spectrum of M points, and the synthesized reception spectrum is input to the IDFT 1305.

The IDFT unit 1305 obtains an M-point time domain signal by applying an M-point IDFT to the input M-point spectrum.
The M-point time domain signal output from the IDFT unit 1305 is input to the adding unit 1306. The adder 1306 adds the output of the IDFT unit 1305 and the output of the symbol replica generation unit 1309 and inputs the addition result to the demodulator 1307. However, since the output of the symbol replica generation unit 1309 is set to 0 at the first iteration, the output result of the IDFT unit 1305 is input to the demodulation unit 1307 as it is.

Demodulation section 1307 performs demodulation based on the modulation scheme applied by mobile station apparatus 102 and converts it into a bit sequence. The output of the demodulator 1307 is input to the decoder 1308.
Decoding section 1308 calculates decoded data bits and coded bits LLR (Log-Likelihood Ratio) using the input demodulated sequence. The latter encoded bit LLR is input to the symbol replica generation unit 1309.
The symbol replica generation unit 1309 uses the LLR input from the decoding unit 1308 to generate a symbol replica. The obtained symbol replica is input to the DFT unit 1310 and the adding unit 1306.

As described above, the adding unit 1306 adds the output of the IDFT unit 1305 and the output of the symbol replica generation unit 1309 (addition for each symbol).
Also, DFT section 1310 applies DFT to the input symbol replica, similarly to DFT section 203 (FIG. 2) of mobile station apparatus 102. The signal after DFT is input to reception replica generation section 1311.
Reception replica generation section 1311 uses each of the reception antennas 901-1 to 901 -N using the post-DFT symbol replica input from DFT section 1310 and the channel estimation value input from channel estimation section 905 (FIG. 9). A reception replica that is a replica of the reception signal at _r is generated.

Here, although not shown in FIG. 13, the signal of the mobile station apparatus 102, for example, the mobile station apparatus 102-3 is a desired mobile station apparatus, and for example, at least the spectrum of the mobile station apparatus 102-2 When partly multiplexed, an input from the DFT unit corresponding to the multiplexed mobile station apparatus 102-2 is input to the reception replica generating unit 1311. That is, the reception replica generation unit 1311 generates a replica of the reception spectrum for each reception antenna in the subcarrier to which the desired mobile station device, for example, the mobile station device 102-3 is transmitted. Calculated received replicas are input to the cancellation unit _{1301-1~1301-N r.}

The cancellation unit _{1301-1~1301-N r,} from the received signal input from the frequency demapping unit _{903-1~903-N r,} subtracts the output of the reception replica generation unit 1311. If both the accuracy of the replica and the channel estimation is complete, canceling unit _{1301-1~1301-N r} will output only the equalizer 1302 noise component. At this time, since the complete symbol replica is input from the symbol replica generation unit 1309 to the addition unit 1306, a signal having no interference component is output from the addition unit 1306.
After the above processing is repeated an arbitrary number of times, the iterative processing unit 904 outputs the decoded data bits calculated by the decoding unit 1308.

According to the first embodiment, the mobile station apparatus 102 can specify whether or not to perform frequency filtering depending on the situation, and can specify the roll-off rate when applying frequency filtering. The transmission method can be determined flexibly. As a result, uplink throughput can be increased. In addition, since all mobile station apparatuses 102 do not always apply frequency filtering, it is possible to reduce the complexity of signal processing in the reception part of the base station apparatus.
In the first embodiment, since the data signal whose band has been expanded is combined by the spectrum combining unit, it is possible to perform transmission with a low PAPR as compared with the case where frequency filtering is not performed. In addition, since synthesis can be performed after equalization, spectra received at different frequencies can be synthesized in phase. That is, a frequency diversity effect can be obtained.

In the above description, the case where the mobile station apparatus and the base station apparatus have known transmission signal roll-off rates has been described. For example, when the control information extracted by the roll-off rate information extraction unit 701 of the roll-off rate determination unit 213 is a parameter related to transmission power control, the roll-off rate setting unit 702 determines the roll-off rate based on the required transmission power. can do. That is, when the required transmission power is low, the mobile station apparatus sets a high roll-off rate in order to lower the PAPR. On the other hand, when the required transmission power is high, the mobile station does not need to lower the PAPR, so a low (or zero) roll-off rate is set.
In the LTE system, the transmission power of the mobile station is not notified to the base station apparatus, but a PH (Power Headroom) indicating a power surplus is notified. However, the period for transmitting the PH is long, and the base station apparatus may not be able to decode correctly. As a result, there is a possibility that the base station apparatus on the receiving side cannot recognize what roll-off rate the mobile station apparatus has transmitted. In such a case, the base station apparatus performs demodulation based on the latest information. As a result, the base station apparatus cannot effectively use the extended reception spectrum and extracts only interference and noise from frequencies outside the use band, so there is a possibility that the transmission characteristics are slightly deteriorated. However, transmission can also be performed without sharing the roll-off rate.
[Second Embodiment]

As described in the first embodiment, in order to perform equalization, a demodulation reference signal (DMRS) is usually transmitted and received.
However, since DMRS uses the spectrum whose gain has been lowered by the frequency filtering described above as it is, there is a possibility that the channel estimation accuracy is extremely deteriorated at the end of the used frequency band. Therefore, in the second embodiment, the channel estimation accuracy is prevented from falling at the end of the used frequency band.

Since the configuration of the receiving part of the base station apparatus according to the second embodiment is the same as that of the first embodiment (FIG. 9), description thereof is omitted.
FIG. 15 is a schematic block diagram of the configuration of the mobile station apparatus 102a according to the second embodiment.
The individual modules constituting the mobile station apparatus 102a are the same as the modules constituting the mobile station apparatus 102 of the first embodiment. However, regarding the mutual connection relationship, the order of the frequency filter unit 1507 and the frequency mapping unit 1506 is reversed. That is, the output of DMRS multiplexing section 1505 is provided to frequency filter section 1507, the output of frequency filter section 1507 is provided to frequency mapping section 1506, and the output of frequency mapping section 1506 is supplied to SC-FDMA signal generation section 1508. Given. The output of roll-off rate determination unit 1513 is also provided to DMRS generation unit 1504. Other connection relationships are the same in the first and second embodiments.
The configuration and functions of the roll-off rate determination unit 1513 and the DMRS generation unit 1504 of the second embodiment are different from those of the roll-off rate determination unit 213 and the DMRS generation unit 204 of the first embodiment. The function remains unchanged in the first and second embodiments.

FIG. 16 is a block diagram showing details of the roll-off rate determining unit 1513.
In FIG. 16, the roll-off rate information extraction unit 1601 extracts control information related to the roll-off rate from the control information input from the control information acquisition unit 1512, and sets the extracted control information as a roll-off rate setting for each signal. Output to the unit 1602. The roll-off rate setting unit 1602 for each signal determines the roll-off rate for each signal according to the information. Therefore, different roll-off rates are determined for each of the data signal and DMRS. Each signal roll-off rate setting unit 1602 outputs each roll-off rate to frequency filter unit 1507, SC-FDMA signal generation unit 1508, and DMRS generation unit 1504. The operation of the DMRS generator 1504 will be described later.
Note that the roll-off rate output to SC-FDMA signal generation unit 1508 may be either the data signal or the roll-off rate for each signal with respect to DMRS.

FIG. 17 is a flowchart for explaining the operation of the roll-off rate determination unit 1513.
In FIG. 17, the roll-off rate information extraction unit 1601 acquires control information from the control information acquisition unit 1512 (step S1701). The roll-off rate information extraction unit 1601 extracts parameters for determining the roll-off rate from the input control information (step S1702). The per-signal roll-off rate setting unit 1602 sets different roll-off rates for the data signal and the DMRS from the extracted parameters (S1703). The per-signal roll-off rate setting unit 1602 outputs the set roll-off rates to the frequency filter unit 1507, the SC-FDMA signal generation unit 1508, and the DMRS generation unit 1504 (S1704).

In the roll-off rate determination unit 213 of the first embodiment, frequency filtering based on the same roll-off rate is applied to the data signal and DMRS. However, in the second embodiment, the data signal and DMRS are applied to the data signal and DMRS. Apply frequency filtering with different roll-off rates.
FIG. 18A shows the pass characteristic 1801 of the roll-off filter when the input signal to the frequency filter unit 1507 is related to the data signal. In this case, the zero output frequency on the high frequency side is (1 + α) M, and the zero output frequency on the low frequency side is standardized as zero. FIG. 18B shows a pass-off characteristic 1802 of the roll-off filter when the input signal to the frequency filter unit 1507 is related to DMRS as a control signal. In this case, the zero output frequency on the high frequency side is (1 + α _DMRS ) M _DMRS , and the zero output frequency on the low frequency side is standardized to be zero. However, in the present embodiment, M is a data bandwidth before application of the roll-off filter, and M _DMRS is a bandwidth of DMRS before application of the roll-off filter.
For example, in LTE, a low PAPR sequence called a Zadoff-Chu sequence is transmitted as DMRS. That is, since DMRS can be transmitted with a lower PAPR than data, there is no need to set a large roll-off rate similar to that of data. That is, the DMRS roll-off rate can be made smaller than the roll-off rate of the data signal. When the DMRS roll-off rate is α _DMRS and the bandwidth is M _DMRS , the bandwidth after the bandwidth expansion is (1 + α _DMRS ) M _DMRS . As described above, this bandwidth is required to be equal to the data bandwidth (1 + α) M. As a result, using the data bandwidth M, the data roll-off rate α, and the DMRS roll-off rate α _DMRS , the bandwidth M _DMRS to be generated by the DMRS generating unit is calculated by the following equation.

That is, the DMRS generation unit 1504 generates a DMRS having a different bandwidth by instructing a roll-off rate different from data from the roll-off rate determination unit 1513, and inputs the DMRS to the DMRS multiplexing unit 1505, unlike the conventional LTE. Will do. Further, the frequency filter unit 1507 generates data and DMRS having the same bandwidth by applying roll-off filters having different roll-off rates to data and DMRS having different bandwidths.
Here, the DMRS generating unit 1504 does not necessarily generate a DMRS having a sequence length of M _DMRS , and may generate a Zadoff-Chu sequence having a sequence length M. The shortage is compensated by a spectrum repeater (same as the spectrum repeater 501 in the first embodiment) in the frequency filter unit 1507.
In this way, by applying a roll-off rate smaller than the roll-off rate for the data signal to the DMRS, the number of spectra in which the transmission energy density is attenuated can be reduced, so that deterioration in channel estimation accuracy can be suppressed. .

  Moreover, although the example which applied the roll-off rate smaller than the roll-off rate with respect to a data signal to DMRS was demonstrated above, you may set the roll-off rate larger than the roll-off rate with respect to a data signal to DMRS. For example, in the Zadoff-Chu sequence in LTE, since the PAPR differs depending on the sequence number, a DMRS having a higher PAPR than the data is transmitted depending on the case. In this way, when a DMRS sequence having a PAPR characteristic worse than that of data must be transmitted, distortion due to the nonlinear amplifier of the power amplifier 305 (FIG. 3) of the transmission signal at the time of DMRS transmission is avoided. be able to.

As described above, by performing frequency filtering with different roll-off rates on the data signal and the DMRS, the channel estimation accuracy can be improved, or by the nonlinear amplifier at the time of DMRS transmission (the power amplifier 305 in FIG. 3). Distortion can be avoided. As a result, throughput can be increased.

[Third Embodiment]
As described in the first embodiment, a frequency diversity effect can be obtained by applying frequency filtering. However, if frequency filtering is also applied to DMRS, degradation of channel estimation accuracy at the end of the used band becomes a problem.
As shown in the second embodiment, although the degradation of channel estimation accuracy can be suppressed by applying frequency filtering with a small roll-off rate to the DMRS, there is a problem that the transmission power of the DMRS increases. Therefore, in the third embodiment, a method for applying frequency filtering without degrading channel estimation accuracy while maintaining DMRS transmission power will be described.

Since the configuration of the mobile station apparatus according to the third embodiment is the same as that of the first embodiment (FIG. 2), description thereof is omitted. The configuration of the reception part of the base station apparatus 101b according to the third embodiment is the same as that of the first embodiment (FIG. 9), but the configuration of the iterative processing unit 904b is different.
FIG. 19 is a schematic block diagram showing the configuration of the iterative processing unit 904b.
As for the individual modules constituting the iterative processing unit 904b of the third embodiment, there is no module added to or deleted from the modules constituting the iterative processing unit 904 of the first embodiment. However, with respect to the mutual connection relationship, the positions of the spectrum synthesizers 1904-1 to 1904 -N _r of the third embodiment are different.
That is, in the third embodiment, the outputs from the frequency demapping units 903-1 to 903-N _r (FIG. 9) are input to the spectrum combining units 1904-1 to 1904 -N _r and the spectrum combining unit the output of _{1904-1~1904-N r} is applied to the cancellation portion _{1901-1~1901-N r.} The output of the equalization unit 1902 is input to the IDFT unit 1905. Other connection relationships are the same in the first and third embodiments.
The configuration and functions of the spectrum synthesizers 1904-1 to 1904 -N _r of the third embodiment are different from the spectrum synthesizer 1304 of the first embodiment, but the configurations and functions of the other modules are the first and the second. There is no change in the third embodiment.

In FIG. 19, spectrum synthesis sections 1903-1 to 1903 -N _r synthesize reception spectrums in which the same phase spectrum is transmitted among (1 + α) M reception spectrums as shown in FIG. 14. , M spectra are generated. Here, in the first embodiment, even if the channel is frequency selective fading, spectrum synthesis is performed after equalization, so the spectrum is synthesized in-phase at the time of synthesis. In this embodiment, the spectrum is synthesized. If the phase of the channel is different at both ends of the, it is not synthesized in the same phase.

However, the received power can be increased statistically by combining. Further, since spectrum synthesis is applied to both data and DMRS, channel estimation section 905 (FIG. 9) estimates the channel after spectrum synthesis using DMRS, and sends it to weight generation section 1903 and reception replica estimation section 1911. The estimated channel estimation value is input.
The output of the spectrum combining unit _{1904-1~1904-N r} are input to the cancellation unit _{1901-1~1901-N r,} subtracting the input from the reception replica generation unit 1911. The output of the cancellation portion _{1901-1~1901-N r} are input to the equalization unit 1902. The equalization unit 1902 performs an equalization process on the spectrum with the number of points M using the channel estimation value of M points output from the weight generation unit 1903. The equalized signal is input to the IDFT unit 1905.
The subsequent processing is the same as in the first embodiment. However, it is possible to eliminate intersymbol interference by repeating signal processing in the iterative processing unit 904b, but it is not always necessary to repeat it.

  As described above, according to the third embodiment, since channel estimation accuracy can be improved by performing spectrum synthesis before performing equalization processing and channel estimation, transmission characteristics can be improved. As a result, in the third embodiment, the uplink throughput can be increased.

A program that operates in a mobile station apparatus and a base station apparatus related to each embodiment of the present invention controls a CPU (Central Processing Unit) and the like so as to realize the functions of the above-described embodiments related to the present invention. It can be a program (a program that causes a computer to function). The program and data information handled by these devices are temporarily stored in the RAM at the time of processing, then stored in various ROMs and HDDs, and read, corrected, and written by the CPU as necessary. As a recording medium for storing the program, a semiconductor medium (for example, ROM, nonvolatile memory card, etc.), an optical recording medium (for example, DVD, MO, MD, CD, BD, etc.), a magnetic recording medium (for example, magnetic tape, Any of a flexible disk etc. may be sufficient. In addition, by executing the loaded program, not only the functions of the above-described embodiment are realized, but also based on the instructions of the program, the processing is performed in cooperation with the operating system or other application programs. Functions of each embodiment of the invention can be realized.
When these programs are distributed in the market, the programs can be stored in a portable recording medium and distributed, or transferred to a server computer connected via a network such as the Internet. In this case, the storage device of the server computer is also included in each embodiment of the present invention. In addition, part or all of the mobile station device and the base station device in each of the above-described embodiments may be typically realized as an LSI that is an integrated circuit. Each functional block of the mobile station apparatus and the base station apparatus may be individually chipped, or a part or all of them may be integrated into a chip. Further, the method of circuit integration is not limited to LSI, and may be realized with a dedicated circuit or a general-purpose processor. The integrated circuit may be either hybrid or monolithic. Moreover, a part of the functions performed by the above program may be realized by hardware and partly by software.
The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes and the like within the scope not departing from the gist of the present invention are patented. It is included in the technical scope of the claims.

  Each embodiment of the present invention can be used in the field of wireless communications.

101: base station apparatus 102-1 to 102-3: mobile station apparatus 207: frequency filter unit 209: transmission antenna 213: roll-off rate determination unit 211: reception antenna 401: input signal 402 in frequency domain of frequency filter unit: Output signal 601 in the frequency domain of the frequency filter unit: signal spectrum 602: signal with repeated signal spectrum 603: pass-off characteristics 901-1 to 901-N _{r of} roll-off filter: receiving antenna 902: SC-FDMA signal receiving unit 904: Repetition processing unit 1513: Roll-off rate determination unit

Claims (14)

A mobile station device that transmits a data signal and a reference signal,
The mobile station apparatus includes a frequency filter unit that filters the data signal and the reference signal,
The roll-off rate of the filter is determined by one constant selected from two or more constants,
Mobile station device.   The mobile station apparatus according to claim 1, further comprising a constant determination unit that selects a constant that determines the roll-off rate.   2. The two or more constants include a constant for setting a zero output frequency within a range of an assigned frequency band of the data signal and the reference signal and a constant for setting outside the range. Or the mobile station apparatus of 2.   The zero output frequency set outside the range of the frequency band assigned to the data signal and the reference signal is set within the range of the frequency band assigned to the data signal and the reference signal of another mobile station device. The mobile station apparatus according to claim 3.   The constant is a roll-off rate of a roll-off filter including a portion having a flat pass characteristic and a gentle curved portion near the cut-off frequency. The mobile station apparatus as described.   5. The movement according to claim 4, wherein when the roll-off rate is zero, the zero output frequency is within the frequency band allocated to the data signal and the reference signal, and the pass characteristic is composed of only a flat part. Station equipment.   The mobile station apparatus according to claim 1, wherein the selected constant is different for each of the data signal and the reference signal.   The mobile station apparatus according to claim 7, wherein the flat part of the pass characteristic of the filter is wide for a reference signal and narrow for a data signal.   The mobile station apparatus according to claim 7, wherein the roll-off rate is large with respect to a reference signal and small with respect to a data signal.   The mobile station apparatus according to any one of claims 2 to 9, wherein the constant determination unit determines the constant based on information shared with a base station apparatus that is a transmission destination of the data signal and the reference signal. .   The mobile station apparatus according to claim 10, wherein the information shared with the base station apparatus is a power headroom. A data signal and a reference signal transmitted from each of a plurality of mobile stations, wherein the data signal and the reference signal transmitted from one mobile station apparatus exceed the allocated frequency band and are allocated to another mobile station apparatus. A signal in which a first state that also occupies a frequency band and a second state in which a data signal and a reference signal transmitted from another mobile station apparatus are contained in the allocated frequency band are mixed is received. One base station device that
A base station apparatus comprising a repetitive processing unit that separates signals by performing repetitive processing on the received signal in the first state. A wireless communication system comprising a base station device and a plurality of mobile station devices,
The transmission units of the plurality of mobile station devices include a frequency filter unit that determines, for each mobile station device, whether to apply frequency filtering to the data signal and the reference signal.
A wireless communication system. Converting a time domain signal to a frequency domain signal;
Mapping the frequency domain signal to an arbitrary frequency;
Filtering the frequency domain signal according to a roll-off rate designated by a roll-off rate determining unit;
Transmitting the frequency domain signal;
In this case, in the process of arranging the frequency domain signal at an arbitrary frequency, whether or not the frequency is arranged so as to overlap with the output of the frequency filter unit of another mobile station, The transmission method, wherein the transmission method is determined by the roll-off rate.

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