JP2013070355A - Transmitter, processor, transmission method, and transmission program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the cell throughput.SOLUTION: In a transmitter 116, data is transmitted to a base station on the basis of the position of a unit frequency band on a frequency axis notified from the base station. The transmitter comprises: an RB selection unit 120 which acquires mapping information indicating that a collection of the unit frequency bands whose positions are contiguous on the frequency axis is allocated in plurality; a transmit signal generation unit 130 which generates a transmit signal having had signals arranged to the RB on the basis of the mapping information acquired by the RB selection unit 120; and a transmit unit 140 which uses a frequency band indicated by a use collection used for transmission among the frequency bands indicated by a plurality of collections to transmit data, and use a frequency band indicated by a non-use collection not used for transmission not to transmit data.

Description

  The present invention relates to a transmission device, a processor, a transmission method, and a transmission program.

  As the amount of data communication increases in recent years, there is an increasing need for a mobile communication system having higher frequency utilization efficiency, and various studies on a one-cell reuse cellular system that uses the same frequency band in all cells. It is being advanced. E-UTRA (Evolved Universal Terrestrial Radio Access), which is being standardized around 3GPP (3rd Generation Partnership Project) as one of the 1-cell reuse cellular systems In the air interface system, an OFDMA (Orthogonal Frequency Division Multiple Access) system is being considered as a downlink transmission system candidate.

  Also, non-contiguous / continuous DFT-S-OFDM (Discrete Fourier Transform Spread OFDM; discrete Fourier transform spread OFDM, which supports non-continuous use of frequency and continuous use of frequency (link OFDM) method) It is being considered as a promising candidate for this transmission system.

  The OFDMA scheme, which is a downlink candidate, is a scheme in which a user accesses in units of resource blocks divided by time and frequency using an OFDM signal excellent in resistance to multipath fading. However, since the OFDMA scheme has high PAPR (Peak-to-Average Power Ratio) ratio, it is not suitable as an uplink transmission scheme with severe transmission power limitation.

  On the other hand, the contiguous DFT-S-OFDM scheme can maintain a good PAPR characteristic with respect to a multicarrier scheme such as OFDM by arranging signals spread by DFT at continuous frequencies, and can ensure a wide coverage. . In addition, the non-constant DFT-S-OFDM scheme can suppress a certain degree of PAPR characteristic degradation while flexibly using a frequency by arranging a signal spread by DFT at a non-continuous frequency.

  In addition, in non-continuous / continuous DFT-S-OFDM, switching between non-continuous and continuous is considered based on transmission power (for example, refer to Patent Document 1, hereinafter referred to as a hybrid system). . If this hybrid method is used, the throughput for the terminal at the center of the cell can be improved while maintaining the cell coverage of the method using only contiguous DFT-S-OFDM, so that the throughput of the entire cell can be improved.

  On the other hand, a transmission scheme that does not transmit part of the frequency spectrum of the contiguous DFT-S-OFDM scheme (hereinafter referred to as Clipped DFT-S-OFDM) has also been studied.

International Publication No. WO2008 / 081876

It has been pointed out that when a non-continuous DFT-S-OFDM scheme is used, discontinuous frequency resources are used, so that harmonic distortion occurs due to an amplifier and a signal leaks out of the band. Hereinafter, this phenomenon is referred to as out-of-band radiation. As a countermeasure against this out-of-band radiation, when using discontinuous RBs, it has been studied to lower the maximum transmission power from the maximum transmission power allowed by the contiguous DFT-S-OFDM. Hereinafter, the reduction amount of the maximum transmission power is referred to as MPR (Maximum Power Reduction).
When this terminal apparatus performs processing for reducing the maximum transmission power, communication is performed with reduced power efficiency, and there is a problem in that a decrease in throughput is caused in some cases. Furthermore, when MPR is not taken into consideration, there is a problem that discontinuous frequency resource arrangement affects other terminal apparatuses in its own system band.

  On the other hand, research on Clipped DFT-S-OFDM is also becoming active. However, when compared with normal DFT-S-OFDM, deterioration of characteristics is unavoidable, and effective proposals have been made for its usage. Absent.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a transmission device, a processor, a transmission method, and a transmission program that can improve cell throughput.

  (1) The present invention has been made in view of the above circumstances, and one aspect of the present invention transmits data to the base station based on the position on the frequency axis of the unit frequency band notified from the base station. Based on the acquisition unit, which is a transmission device, acquires mapping information indicating that a plurality of sets of the unit frequency bands whose positions are continuous on the frequency axis are allocated, and the mapping information acquired by the acquisition unit The data is transmitted using a frequency band indicated by a use set used for transmission among a plurality of frequency bands indicated by the set, and the data is indicated using a frequency band indicated by an unused set other than the use set. And a transmitting unit that does not transmit.

  (2) One aspect of the present invention is the transmission apparatus, wherein the transmission unit selects the unused set from the set indicated by the mapping information acquired by the acquisition unit based on the mapping information. A selection unit is provided.

  (3) According to one aspect of the present invention, in the transmission device, the transmission unit includes a signal arrangement unit that arranges a signal in a frequency band indicated by mapping information acquired by the acquisition unit, and the signal arrangement unit receives a signal. A signal removing unit that removes a signal arranged in a frequency band indicated by an unused set selected by the set selection unit from among the arranged signals, and using the signal removed by the signal removing unit It is characterized by transmitting data.

  (4) According to one aspect of the present invention, in the transmission device described above, a clipping ratio is calculated based on a sum of frequency bands included in each of the sets and a frequency band included in each of the sets. A frequency band to be used for transmission is selected based on the clipping rate.

  (5) According to an aspect of the present invention, in the transmission device, the set selection unit erases a frequency band of a part of the set when the calculated clipping rate is smaller than a predetermined threshold. Then, it is determined, and a frequency band other than the frequency band determined to be deleted is selected as the use frequency band.

(6) In one embodiment of the present invention, in the above transmission device, the threshold value is any one of a modulation scheme, a coding rate, a transmission rate, a system bandwidth, a distance on a frequency axis between sets, or a system band. It is set based on one or a combination of two or more.

(7) According to one aspect of the present invention, in the transmission device, the collection set selection unit sets an occupancy ratio that is a ratio of frequency bands included in a set to a total of frequency bands included in each of the sets for each set. The clipping ratio is calculated based on the calculated occupation ratio for each set.

  (8) According to one aspect of the present invention, in the transmission device, the set selection unit acquires transmission power designated from a base station device, and determines in advance the frequency band of each set and the acquired transmission power. The use frequency band is selected based on the reduced amount of maximum transmission power.

  (9) According to one aspect of the present invention, in the transmission device described above, the set selection unit performs clipping based on a total frequency band obtained by summing up the frequency bands of the sets and the frequency bands of the sets. A rate is calculated, and the use frequency band is selected based on the calculated clipping rate, the acquired transmission power, and a predetermined reduction amount of the maximum transmission power.

(10) One aspect of the present invention is characterized in that, in the transmission device, the signal to be arranged by the signal arrangement unit is a signal obtained by performing time-frequency conversion on the data.

  (11) According to one aspect of the present invention, in the transmission device, when the transmission unit includes a frequency band prohibited from being used in the plurality of subcarriers designated by the base station, A transmission signal in which a signal is arranged in a frequency band other than the frequency band prohibited from being used is transmitted.

(12) According to one aspect of the present invention, in the above transmission device, the transmission unit is notified from the base station device to transmit a transmission signal in a plurality of system bands, and a total transmission power required for transmission is predetermined. A resource block control unit that clips all signals in at least one system band when the value exceeds the value, and a signal is allocated to subcarriers in the system band that the resource block control unit does not perform clipping And a transmission signal generating unit that generates the transmitted signal.

(13) One aspect of the present invention is characterized in that, in the above-described transmission device, the transmission unit transmits data to be transmitted in a system band that is a target of clipping by the resource block control unit, in another system band. And

(14) In one aspect of the present invention, in the transmission device, the transmission signal generation unit performs clipping so that the number of subcarriers used in the other system band is the number of subcarriers designated by the base station. It is characterized by performing.

(15) One aspect of the present invention is characterized in that, in the above transmission apparatus, the predetermined value is determined based on MPR.

  (16) According to one aspect of the present invention, in the transmission device described above, the transmission unit is notified from the base station device that a transmission signal is transmitted in a plurality of system bands, and is based on a positional relationship of system bands used for transmission. A resource block control unit that clips all signals in at least one system band, and a transmission signal in which signals are arranged for subcarriers in the system band that are not targeted for clipping by the resource block control unit And a transmission signal generation unit.

(17) One aspect of the present invention is characterized in that, in the above transmission apparatus, the positional relationship of the system bands used for the transmission is whether or not the used system bands are continuous in the frequency domain. .

(18) One aspect of the present invention is characterized in that, in the transmission device, the signal to be arranged by the transmission signal generation unit is a signal obtained by performing time-frequency conversion on the data. .

  (19) According to one aspect of the present invention, mapping information indicating that a plurality of sets of unit frequency bands in which positions on the frequency axis of unit frequency bands are continuous on the frequency axis is assigned is obtained. The processor further includes a set selection unit that selects a part of a set as an unused set that is not used for transmission based on the mapping information.

  (20) One aspect of the present invention is a transmission method executed by a transmission device that transmits data to the base station based on a position on a frequency axis of a unit frequency band notified from the base station, An acquisition procedure for acquiring mapping information indicating that a plurality of sets of the unit frequency bands whose positions are continuous on the frequency axis are allocated, and a plurality of the sets are based on the mapping information acquired by the acquisition procedure. A transmission procedure in which the data is transmitted using a frequency band indicated by a use set used for transmission among the frequency bands indicated, and the data is not transmitted using a frequency band indicated by an unused set other than the use set; It is the transmission method characterized by having.

  (21) One embodiment of the present invention is directed to a computer of a transmission device that transmits data to the base station based on the position on the frequency axis of the unit frequency band notified from the base station. An acquisition step of acquiring mapping information indicating that a plurality of sets of the unit frequency bands that are continuous with each other has been allocated, and based on the mapping information acquired by the acquisition step, out of the frequency bands indicated by the plurality of sets A transmission step for transmitting the data using a frequency band indicated by a use set used for transmission and not transmitting the data using a frequency band indicated by an unused set other than the use set. It is a program.

  According to the present invention, cell throughput can be improved.

It is the schematic which shows the structure of the radio | wireless communications system in 1st Embodiment. It is a schematic block diagram which shows the structure of the terminal device in 1st Embodiment. It is a figure for demonstrating operation | movement of the RB selection part of 1st Embodiment, and a transmission signal. It is the schematic which shows the structure of the radio | wireless communications system in 2nd Embodiment. It is a schematic block diagram which shows the structure of the terminal device in 2nd Embodiment. It is a figure for demonstrating the operation | movement of the control part of 2nd Embodiment, and a transmission signal. It is the schematic which shows the structure of the radio | wireless communications system in 3rd Embodiment. It is a schematic block diagram which shows the structure of the terminal device in 3rd Embodiment. It is a figure for demonstrating the operation | movement of the RB selection part of 3rd Embodiment, and a transmission signal. It is the schematic which shows the structure of the radio | wireless communications system in 4th Embodiment. It is a schematic block diagram which shows the structure of the base station apparatus in 4th Embodiment. It is the schematic which shows the structure of the radio | wireless communications system in 5th Embodiment. It is a schematic block diagram which shows the structure of the terminal device in 5th Embodiment. It is a figure for demonstrating the process of a transmission part, when the number of system bands and the number of DFT-S-OFDM which a transmitter can transmit simultaneously differ.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to this embodiment, A various change is possible.

 In each embodiment, description will be made using a frequency component (hereinafter also referred to as a frequency RB) of a resource block including a plurality of subcarriers as an example of a unit frequency band that is a unit region in the frequency direction. Here, the resource block is a two-dimensional radio resource composed of a frequency component and a time component. The unit frequency band may be a subcarrier. A cluster is a set of unit frequency bands in which positions on the frequency axis of unit frequency bands are continuous on the frequency axis. In the present embodiment, since the frequency band obtained by dividing the frequency component of the resource block on the frequency axis is designated as the frequency band that can be used for transmission from the base station apparatus, the cluster has a frequency RB that is continuous on the frequency axis. This is a set of frequency RBs that are being used. Further, the frequency RB and the subcarrier represent a bandwidth.

<First Embodiment>
FIG. 1 is a schematic diagram illustrating a configuration of a wireless communication system 10 according to the first embodiment. The wireless communication system 10 according to the present embodiment includes a base station device 2 and terminal devices 1-1,..., 1-N (N is a positive integer) N terminal devices 1-i (i is 1 to N). Integer).
Transmission from each terminal apparatus 1-i to the base station apparatus 2 (hereinafter also referred to as uplink) is the DFT-S-OFDM scheme, but may be other schemes. Transmission from the base station apparatus 2 to each terminal apparatus 1-i (hereinafter also referred to as downlink) is the OFDMA scheme, but may be other schemes.

Base station apparatus 2 determines the number of frequency RBs for each cluster (hereinafter also referred to as frequency RB number), the RB position, and the number of clusters for each terminal apparatus 1-i. Then, the base station apparatus 2 wirelessly transmits RB information (mapping information) R including the frequency RB number, the RB position, and the cluster number determined for each terminal apparatus 1-i to the corresponding terminal apparatus 1-i. Hereinafter, the i terminal apparatuses 1-i are described as having the same configuration, but the embodiment of the present invention is not limited to this.
The base station apparatus 2 receives the transmission data transmitted from each terminal apparatus 1-i and decodes the received transmission data. Here, even if each terminal device 1-i erases a part of transmission data and transmits the transmission data partially erased, the base station device 2 uses the known decoding technique to transmit the original transmission data. Data can be decrypted.
When the number of clusters is 2, the number of clusters may be information on whether to divide clusters.

  Each terminal apparatus 1-i receives a transmission signal wirelessly transmitted from the base station apparatus 2. Each terminal device 1-i wirelessly transmits a signal to the base station device 2.

Each terminal device 1-i accesses, for example, the base station device 2 in units of RBs (resource blocks). Each RB is composed of 4 subcarriers, and the total number of RBs is 16. The number of subcarriers constituting the RB is an example, and other values may be used, and the total number of RBs is not particularly limited. The radio communication system 10 will be described for the uplink, which is transmission from the terminal apparatus 1-i to the base station apparatus 2, but is applicable to the downlink, and the modulation method is limited to DFT-S-OFDM. Not what you want.
When the base station apparatus 2 decodes a signal transmitted from each terminal apparatus 1-i using turbo equalization, which will be described later, each terminal apparatus 1-i may use DFT-S-OFDM. preferable.

  FIG. 2 is a schematic block diagram showing the configuration of the terminal device 1-i in the first embodiment. The terminal device 1-i includes a reception antenna unit 112, a wireless unit 113, an A / D conversion unit 114, a reception unit 115, and a transmission device 116. The transmission device 116 includes an encoding unit 100, a modulation unit 101, an S / P (serial / parallel) conversion unit 102, a DFT unit 103, and a transmission unit 140. The transmission unit 140 includes an RB selection unit (set selection unit, acquisition unit) 120, a transmission signal generation unit 130, an IFFT unit 106, a P / S (parallel / serial) conversion unit 107, and a CP (Cyclic Prefix) insertion. Unit 108, D / A conversion unit 109, radio unit 110, and transmission antenna unit 111. The transmission signal generation unit 130 includes a subcarrier mapping unit (signal arrangement unit) 104 and a signal removal unit 105.

The encoding unit 100 receives the transmission data TD1, and performs error correction encoding on the input transmission data TD1. Then, coding section 100 outputs transmission data after error correction coding to modulation section 101.
Modulation section 101 modulates transmission data input from encoding section 100 and outputs the modulated transmission signal to S / P conversion section 102.

  The S / P conversion unit 102 converts the transmission signal input from the modulation unit 101 from a serial signal to a parallel signal, and outputs the converted parallel signal to the DFT unit 103. Specifically, the S / P converter 102 multiplies the number of RBs (hereinafter referred to as TRB) used for transmission by the number of subcarriers constituting the resource block (here, 4 as an example). Convert to

  The DFT unit 103 converts the parallel signal input from the S / P conversion unit 102 into a frequency domain signal by performing a discrete Fourier transform. As a result, the signal to be arranged by the subcarrier mapping unit (signal arrangement unit) 104 is a signal obtained by performing time-frequency conversion on the transmission data TD1. DFT section 103 outputs the converted frequency domain signal to subcarrier mapping section 104 of transmission signal generation section 130.

  The reception antenna unit 112 receives the transmission signal transmitted from the base station apparatus 2 and outputs the received transmission signal to the radio unit 113. Radio section 113 converts the transmission signal input from reception antenna section 112 into a baseband, and outputs the converted signal to A / D conversion section 114. The A / D conversion unit 114 converts the signal input from the wireless unit 113 into a digital signal, and outputs the converted digital signal to the reception unit 115.

  The reception unit 115 performs reception processing on the digital signal input from the A / D conversion unit 114. For example, the reception unit 115 extracts the RB information R and outputs the extracted RB information R to the RB selection unit 120.

The RB selection unit 120 determines the number of clusters from the position of the resource block included in the RB information R input from the reception unit 115. If there are a plurality of clusters, the RB selection unit 120 is based on the number of RBs for each cluster included in the RB information R. Thus, it is determined whether or not to clip RBs included in some of the plurality of clusters. Here, to clip means to erase. That is, the RB selection unit 120 determines whether to use all of the plurality of frequencies RB based on the configuration of the frequency RB designated by the base station apparatus 2. Note that the RB selection unit 120 determines whether to use all of the plurality of frequencies RB based on the configuration of subcarriers in the frequency domain designated by the base station apparatus 2.
If the RB selection unit 120 determines to clip, the RB selection unit 120 determines a clip target cluster to be clipped based on the number of RBs for each cluster indicated by the RB information R.
That is, the RB selection unit 120 selects a used frequency resource block that is a frequency component of a resource block used for transmission based on the total of unit frequency bands included in each cluster and the number of frequencies RB included in each cluster. To do.

The RB selection unit 120 outputs the clipping information C indicating the determined clip target cluster to the signal removal unit 105 of the transmission signal generation unit 130.
Further, the RB selection unit 120 generates mapping information indicating to which RB the frequency domain signal input from the DFT 103 is allocated based on the RB position indicated by the RB information R input from the reception unit 115. Then, RB selection section 120 outputs the mapping information to subcarrier mapping section 104 of transmission signal generation section 130.

  Based on the mapping information input from RB selection section 120, subcarrier mapping section 104 maps the frequency domain signal input from DFT section 103 to each subcarrier. Subcarrier mapping section 104 outputs the mapped signal to signal removal section 105.

  The signal removal unit 105 clips the cluster signal indicated by the clipping information C input from the RB selection unit 120 among the signals input from the subcarrier mapping unit 104. The signal removal unit 105 outputs the signal after removal to the IFFT unit 106 as a transmission signal.

  The transmission signal generation unit 130 is designated by the base station apparatus 2 using the converted frequency domain signal input from the DFT unit 103 and the mapping information and clipping information C input from the RB selection unit 120. A transmission signal in which signals are arranged with respect to some frequency resource blocks of the plurality of frequency resource blocks is generated.

In other words, the transmission signal generation unit 130 generates a transmission signal based on the determination of the RB selection unit 120 as to whether or not to use all of the plurality of frequency resource blocks specified from the base station apparatus 2. More specifically, the transmission signal generation unit 130 generates a transmission signal in which a signal is arranged for the frequency resource block selected by the RB selection unit 120.
That is, the transmission signal generation unit 130 uses a part of the designated frequency resource block based on the configuration of the designated frequency resource block from the base station apparatus 2, and transmits the designated frequency resource block. Switch between using all.

IFFT section 106 performs inverse fast Fourier transform on the transmission signal input from subcarrier mapping section 104 to convert the transmission signal in the frequency domain to the transmission signal in the time domain. IFFT section 106 outputs the converted transmission signal in the time domain to P / S conversion section 107.
The P / S conversion unit 107 converts the time domain transmission signal input from the IFFT unit 106 from a parallel signal to a serial signal, and outputs the converted serial signal to the CP insertion unit 108.

CP insertion section 108 inserts CP (a signal obtained by copying the symbol after IFFT) into the serial signal input from P / S conversion section 107, and outputs the signal after CP insertion to D / A conversion section 109. .
The D / A conversion unit 109 converts the signal input from the CP insertion unit 108 from a digital signal to an analog signal, and outputs the converted analog signal to the radio unit 110.
Radio section 110 up-converts the analog signal input from D / A conversion section 109 into a radio frequency band signal, and transmits the up-converted signal from transmission antenna section 111.

Note that the configuration for performing clipping in the present invention is not limited to that shown in FIG. 2, and the function of the signal removal unit 105 may be realized by the subcarrier mapping unit 104 or the like.
Further, the order of the signal removal unit 105 and the subcarrier mapping unit 104 may be switched. In this case, the signal removal unit 105 removes a part of the frequency domain signal input from the DFT unit 103.

Then, the signal obtained by the removal by the signal removal unit 105 by the subcarrier mapping unit 104 may be arranged on the subcarrier indicated by the mapping information input from the RB selection unit 120. Here, the RB selection unit 120 stores mapping information and clipping information C in association with each other in a predetermined relationship. Thus, it can be said that RB selection section 120 determines whether or not to use all of the plurality of subcarriers based on the subcarrier configuration in the frequency domain designated by base station apparatus 2.
In this case, the transmission signal generation unit 130 can generate a transmission signal in which signals are arranged for some subcarriers among a plurality of subcarriers designated by the base station apparatus 2.

<Details of Processing of RB Selection Unit 120>
Next, details of the processing of the RB selection unit 120 will be described using an example. In this example, it is assumed that the RB information R specified by the base station apparatus 2 is either a continuous RB or two continuous RBs. Hereinafter, this group of consecutive RBs is referred to as a cluster. Here, a “cluster” composed of a plurality of RBs may be referred to as a “bundle” composed of a plurality of RBs. In other words, in this example, there is one cluster or two clusters. Hereinafter, the case of one cluster is referred to as a single cluster, and the case of two clusters is referred to as a double cluster.

In the case of a double cluster, the frequency band is wider than in the case of a single cluster using the same number of RBs. As a result, when the amplifier included in the wireless unit 110 amplifies the signal in a high output region, nonlinearity is added, so that the amplified signal is distorted, and the influence of the signal appears outside the band. Further, as the distance on the frequency axis between the clusters of the double clusters increases, the influence of distortion appears in a region away from the system band, so that the influence on other systems outside the band becomes significant.
In addition, when the signal of one of the double clusters is removed, especially when a DFT-S-OFDM signal is used, the PAPR (Peak to Average Power Relation) characteristics are degraded compared to the single cluster, and therefore, in-band However, the out-of-band influence is smaller than in the case of the double cluster before the signal is removed.

  In the present embodiment, the RB selection unit 120 determines the clipping information C by the following process, for example. First, the RB selection unit 120 determines whether it is a single cluster or a double cluster from the RB information R notified from the base station apparatus 2. The RB selection unit 120 determines that clipping is not performed in the case of a single cluster. In the case of a double cluster, the RB selection unit 120 calculates the RB occupancy rate RO1 and the RB occupancy rate RO2 according to the following equations. Here, the RB occupancy rate RO1 or RO2 is the number of RBs of cluster 1 or cluster 2 in the total number of RBs designated by the base station apparatus 2, respectively.

RO1 = NRB1 / (NRB1 + NRB2) (1)
RO2 = NRB2 / (NRB1 + NRB2) (2)

  Here, NRB1 and NRB2 are the numbers of RBs arranged in cluster 1 and cluster 2, respectively. Then, the RB selection unit 120 calculates a clipping rate CR, which is the minimum value of the RB occupancy rate, according to the following equation.

  CR = Min {RO1, RO2} (3)

Here, Min {a, b} is a function that selects the smaller one of a and b.
When the clipping ratio CR is smaller than a predetermined clipping threshold, the RB selection unit 120 determines to delete the signal allocated to the frequency RB of the cluster having a small number of frequency RBs to be used, and the frequency RB other than the frequency RB to be deleted. Is selected as a used frequency resource block. On the other hand, when the clipping ratio CR is equal to or greater than a predetermined clipping threshold, the RB selection unit 120 determines that the signal assigned to the frequency RB of the cluster having a small number of frequencies RB to be used is not deleted, and all the frequencies RB Is selected as a used frequency resource block.

That is, the RB selection unit 120 selects a use frequency resource block based on the number of resource blocks included in each cluster. Specifically, the RB selection unit 120 calculates a clipping rate based on the total number of resource blocks included in each cluster and the number of resource blocks included in each cluster, and sets the calculated clipping rate. Based on this, the used frequency resource block is selected. Specifically, for example, when the calculated clipping ratio is smaller than a predetermined threshold, the RB selection unit 120 determines to delete the frequency band of a part of the set, and other than the frequency band determined to be deleted. Is selected as the frequency band to be used.
As described above, the RB selection unit 120 selects a use frequency band that is a frequency band used for transmission based on the number of unit frequency bands included in each cluster.

  As described above, the control of the RB selection unit 120 considers the trade-off between the characteristic deterioration due to clipping and the influence of out-of-band radiation due to double clusters. When the clipping ratio CR is small, the RB selection unit 120 performs clipping within a range in which characteristic degradation due to clipping is allowed, and reduces the cluster used for transmission from a double cluster to a single cluster, thus reducing the influence of out-of-band radiation. be able to.

  For the clipping threshold, the modulation method, coding rate, transmission rate, system bandwidth, distance on the frequency axis between clusters, or system band (system band is a frequency band for operating the system, (Which means that the frequency band is 800 MHz band and 5 GHz band) is set by any one or a combination of two or more, so that clipping at the time of double cluster can be controlled more appropriately. The table shown below is an example in which the clipping threshold is set based on the modulation method.

  Here, BPSK is Binary Phase Shift Keying (two-phase shift keying), QPSK is Quadrature Phase-Shift Keying (four-phase shift keying), and 16QAM is 16 Quadrature Amplitude Modulation. The relationship between the respective clipping thresholds is X1> X2> X3.

  The reason for setting the threshold in this way is that the larger the number of multi-values, the greater the effect of characteristic deterioration due to clipping. That is, the clipping threshold may be set lower as the number of multi-values increases. Thereby, as the multi-value number increases, the ratio of the number of RBs to be clipped with respect to the total number of RBs decreases, so that the influence of characteristic deterioration due to clipping can be reduced.

  When setting the clipping threshold based on the coding rate or the transmission rate, the table may be set with the same tendency. Regarding the coding rate, the higher the coding rate, the lower the error correction capability. Therefore, unless the number of RBs to be clipped is reduced, the base station device 2 that is a receiving device cannot be decoded. For this reason, the clipping threshold may be set lower as the coding rate is higher. As a result, the higher the coding rate, the smaller the ratio of the number of RBs to be clipped to the total number of RBs. Therefore, it is possible to reduce the influence of deterioration in error correction capability due to clipping.

  As for the transmission rate, the higher the transmission rate, the higher the reception error rate (index indicating the ratio of errors in received data such as frame error rate, block error rate, and bit error rate), so the number of RBs to be clipped does not decrease Then, the base station device 2 that is a receiving device cannot decode. For this reason, the higher the transmission rate, the lower the clipping threshold may be set. As a result, the higher the transmission rate, the smaller the ratio of the number of RBs to be clipped to the total number of RBs, so that the increase in error reception error rate due to clipping can be reduced.

The advantage of setting the clipping threshold in the system bandwidth is based on the fact that the narrower the system bandwidth, the longer the distance on the frequency axis between the clusters in the case of double clusters. This is because, as the distance on the frequency axis between clusters is longer, the influence of distortion appears in a region away from the system band, and the influence on other systems existing outside the band becomes significant.
Therefore, the clipping threshold may be set higher as the system bandwidth is narrower. Thereby, when the system bandwidth is narrow, the influence on other systems existing outside the band can be reduced.

  Note that, based on the same principle, the clipping threshold may be set higher as the distance between the clusters on the frequency axis is shorter. Thereby, when the distance on the frequency axis between clusters is short, the influence on other systems existing outside the band can be reduced.

  The advantage of setting the clipping threshold for each system band is based on the fact that the tolerance to interference in other systems adjacent to the system differs for each system band. Therefore, when the resistance to interference in other adjacent systems is weak, the threshold value is set high, so that the double cluster can be avoided as much as possible. Thereby, out-of-band radiation to other adjacent systems can be reduced.

  When the number of clusters is M (M is a positive integer), the RB selection unit 120 calculates the RB occupancy ROj of the cluster j (j is an integer from 1 to M) according to the following equation (4).

  Here, NRBj is the number of RBs arranged in the j-th cluster. Then, the RB selection unit 120 calculates a clipping rate CR, which is the minimum value of the RB occupancy rate, according to the following equation (5). Here, the clipping ratio means the ratio of the number of subcarriers belonging to the cluster having the smallest number of subcarriers constituting the cluster to the total number of subcarriers designated by the base station apparatus 2.

  CR = Min {RO1,..., ROM} (5)

  Note that the RB selection unit 120 may use a value corrected as the RB occupation ratio using the correction value. Specifically, for example, in the case of a double cluster, the RB selection unit 120 may use the correction values X and Y to set the RB occupancy of cluster 1 to RO1 + X and the RB occupancy of cluster 1 to RO2 + X. Here, the correction value X and the correction value Y may be determined based on the magnitude relationship between the frequencies of the respective clusters.

  Further, the RB occupancy rate RO may be divided into a plurality of RB occupancy classes, and the RB selection unit 120 may calculate the clipping rate based on the RB occupancy class. Specifically, for example, as an RB occupancy class, an RB occupancy rate RO is a or more and less than b (a and b are numbers from 0 to 1, for example, a is 0 and b is 0.3), and It is assumed that there is a class B that is greater than or equal to b and less than c (c is a number from 0 to 1, for example, c is 0.5). In the base station device 2, the RB occupation class and the RB occupation rate RO are stored in association with each other.

In the case of a double cluster, when the RB occupation class for each cluster is notified from the base station apparatus 2, the RB selection unit 120 may calculate the clipping rate based on the RB occupation class. Specifically, in the above case, when the RB occupancy class of cluster 1 is class A and the RB occupancy class of cluster B is class B, the RB occupancy RO of class A is calculated as the clipping ratio CR.
As a result, the RB selection unit 120 does not need to calculate the RB occupancy rate of each cluster, and thus the processing for calculating the clipping rate CR can be reduced.

  FIG. 3 is a diagram for explaining the operation of the RB selection unit 120 and the transmission signal of the first embodiment. In the figure, a rectangular frame indicates RB, and a hatched portion indicates a subcarrier. One RB includes 4 subcarriers. In the figure, the total number of RBs that can be used is 8, and only the case of a double cluster is shown.

  FIG. 3A shows the position on the frequency axis of the RB designated by the base station apparatus 2. In the figure, the horizontal axis represents frequency and the vertical axis represents amplitude. In the upper part of FIG. 3A, it is shown that four RBs are designated for the cluster C31 and two RBs are designated for the cluster C32. Further, in the lower part of FIG. 3A, it is shown that five RBs are designated for the cluster C33 and one RB is designated for the cluster C34.

FIG. 3B shows the position on the frequency axis of the spectrum (subcarrier) to be actually transmitted. In the figure, the horizontal axis represents frequency and the vertical axis represents amplitude. In the upper diagram of FIG. 3B, signals assigned to RBs of all clusters (C31 and C32) designated by the base station device 2 are shown.
The lower diagram of FIG. 3B shows signals assigned to RBs included in the remaining cluster C33 obtained by clipping the RB included in the cluster C34. Note that the clipped RB subcarriers are outlined.

  In FIG. 3, a predetermined threshold value for determining whether clipping is possible is 0.2. In the upper diagram of FIG. 3, since the RB number NRB1 of the cluster C31 is 4 and the RB number NRB2 of the cluster C32 is 2, the clipping ratio CR is 0.33. In this case, since the clipping ratio CR is a value of 0.2 or more, the RB selection unit 120 does not perform clipping.

In the lower diagram of FIG. 3, since the RB number NRB1 of the cluster C33 is 5 and the RB number NRB2 of the cluster C34 is 1, the clipping ratio CR is 0.166. In this case, since the clipping ratio CR is a value less than 0.2, a cluster located in the figure (a cluster with a small number of RBs included) is clipped.
By controlling the RB selection unit 120 in this way, it is possible to easily switch between non-contiguous DFT-S-OFDM and clipped DFT-S-OFDM, and efficient communication while suppressing adverse effects such as out-of-band radiation. Can do.

In the present embodiment, the case where the cluster for clipping is set is determined by the above-described equation and a predetermined threshold. However, the present invention is not limited to the embodiment. When there are N clusters, the RB selection unit 120 can determine a cluster to be clipped by setting the above-mentioned RB occupancy ratio to be compared to N.
In this case, the RB selection unit 120 may clip all the clusters showing the RB occupancy smaller than the predetermined clipping threshold, or may clip only the cluster having the smallest RB occupancy.

  Further, when the RB is divided and arranged, the RB selection unit 120 is configured such that the number of RBs included in the cluster is smaller than a predetermined RB threshold (for example, 2) (for example, the number of RBs included in the cluster is smaller). (When 1) may be clipped.

Further, when performing MIMO transmission, the RB selection unit 120 is individually configured for each antenna (for each antenna port: an antenna port is configured by one or more antennas and can be physically regarded as the same antenna). The cluster may be clipped based on the set clipping setting, or the cluster may be clipped based on the same clipping setting.
The same correspondence can be applied to the MIMO transmission in the embodiment described below.

  As described above, in the terminal device 1-i of the first embodiment, the RB selection unit 120, when there are a plurality of clusters designated from the base station device 2, has clusters for all subcarriers designated from the base station device 2. The clipping ratio, which is the ratio of the number of subcarriers belonging to the cluster having the smallest number of subcarriers, is calculated. Then, when the calculated clipping rate is smaller than a predetermined threshold, the RB selection unit 120 generates clipping information C indicating a command to clip a subcarrier belonging to the cluster having the smallest number of subcarriers.

Based on the clipping information C, the signal removal unit 105 generates a transmission signal obtained by removing the subcarrier signal indicated by the clipping information C from the mapped signal input from the subcarrier mapping unit 104.
Thereby, the signal removal part 105 can make an out-of-band radiation smaller by clipping one of the double clusters than when not clipping.

  Note that the RB selection unit 120 may determine whether or not to clip a signal arranged on a subcarrier of a cluster according to the frequency position of the double cluster. Specifically, for example, the RB selection unit 120 may determine to clip a cluster when the frequency band between double clusters is larger than a predetermined frequency threshold. In general, as the frequency position of the double cluster increases, the influence outside the band increases. However, when the frequency position of the double cluster increases, the terminal apparatus 1-i clips the signal arranged on the subcarrier of any cluster. Therefore, out-of-band radiation can be reduced.

  In the present embodiment, the RB selection unit 120 selects the frequency RB to be used for transmission based on the RB occupancy rate, but is not limited to this. The RB selection unit 120 may select a used subcarrier to be used for transmission based on the ratio of the number of subcarriers included in the cluster to the total number of subcarriers designated by the base station apparatus. That is, the frequency RB or the subcarrier may be used as the unit frequency band, and the RB selection unit 120 may select a cluster to be used for transmission from a plurality of clusters based on the position of the unit frequency band on the frequency axis.

  In summary, the RB selection unit 120 as an acquisition unit acquires mapping information indicating that a plurality of sets (clusters) of the unit frequency bands whose positions are continuous on the frequency axis are allocated. Then, the subcarrier mapping unit (signal arrangement unit) 104 arranges signals in the set indicated by the mapping information acquired by the RB selection unit 120 as an acquisition unit. Also, the RB selection unit 120 as the set selection unit selects an unused set that is not used for transmission from the set indicated by the acquired mapping information, based on the mapping information. Next, the signal removal unit 105 removes the signal assigned to the frequency band indicated by the unused set selected by the RB selection unit 120 as the set selection unit from the signals after the data placement unit places data. .

  Thereby, the transmission part 140 transmits data to a base station using the signal which the signal removal part 105 removed. That is, the transmission unit 140 transmits data using a frequency band indicated by a use set used for transmission among a plurality of sets indicated by the mapping information acquired by the RB selection unit 120 serving as an acquisition unit, and other than the use set Data is not transmitted using a frequency band indicated by an unused set that is a set and is not used for transmission.

  As a result, the terminal apparatus signal 1-i removes a signal assigned to a cluster that is not used for transmission from a plurality of clusters, and transmits the signal after the removal to the base station apparatus, so that it is out of the transmission band. Therefore, out-of-band radiation can be made smaller than when all the clusters are used for transmission.

<Second Embodiment>
Next, the second embodiment will be described. FIG. 4 is a schematic diagram illustrating the configuration of the wireless communication system 10b according to the second embodiment. The configuration of the wireless communication system 10b in the second embodiment is such that each terminal device 1-i of the wireless communication system 10 in the first embodiment of FIG. 1 is changed to a terminal device 1b-i. Since the configuration of the radio communication system 10b in the second embodiment is the same as the configuration of the radio communication system 10 in the first embodiment, the description thereof is omitted.

  FIG. 5 is a schematic block diagram showing the configuration of the terminal device 1b-i in the second embodiment. Here, the terminal device 1b-i (FIG. 5) according to the present embodiment is obtained by changing the transmission unit 140 to the transmission unit 140b with respect to the terminal device 1-i (FIG. 2) according to the first embodiment. It has become. Specifically, the RB selection unit 120 of the transmission unit 140 is changed to an RB selection unit (frequency band selection unit) 120b of the transmission unit 140b. In addition, the same code | symbol is attached | subjected to the function part which has the same function as the terminal device 1-i (FIG. 2) of 1st Embodiment, and the description is abbreviate | omitted.

The RB selection unit 120b of the present embodiment has the same function as the RB selection unit 120 of the first embodiment, but the following functions are further added.
The RB selection unit 120b performs non-continuous DFT-S-OFDM (hereinafter also referred to as scheme B) and Clipped DFT-S-OFDM (hereinafter referred to as scheme) according to the clipping rate in an environment where the maximum transmission power is limited. (Also referred to as C).

<Details of Processing of RB Selection Unit 120b>
Hereinafter, details of the processing of the RB selection unit 120b will be described.
In a general wireless communication system, the maximum transmission power may be limited in consideration of the influence of radio waves on the human body. In addition, the high power amplifier built in the transmitter cannot compensate for linear operation at an operating point with high input power, and uses a signal strong against nonlinear operation, particularly in the uplink from the terminal device to the base station device 2. It is desirable to do.

  For example, contiguous DFT-S-OFDM is a signal with strong nonlinearity. Here, the linearity of the high power amplifier will be briefly explained. This is the ability to amplify the input power at a constant rate. When it has nonlinearity, the amplification factor at high input power is higher than the low input power. It will go down. This is sometimes called saturation.

  The RB selection unit 120b uses the reduction when the maximum transmission power is lower than the maximum transmission power allowed by the continuous DFT-S-OFDM as an index for switching between the non-continuous DFT-S-OFDM and the clipped DFT-S-OFDM. A value called power MPR (Maximum Power Reduction) is used. The RB selection unit 120b can suppress the influence of out-of-band radiation by reducing the maximum transmission power.

  As described above, this MPR should basically be determined depending on the high power amplifier of the transmitting apparatus. However, in order to simplify the explanation, in the case of continuous DFT-S-OFDM, 2 dB, non -In the case of contiguous DFT-S-OFDM, the following description will be given assuming that it is set to 7 dB.

Here, the processing of the RB selection unit 120b will be described as an example of a situation in which the maximum transmission power of the terminal device 1b-i is 23 dBm and transmission power control is performed and transmission must be performed at 23 dBm.
In this case, since the above-described MPR is set, 21 dBm is transmitted for continuous DFT-S-OFDM (hereinafter also referred to as scheme A), and 16 dBm is transmitted for non-continuous DFT-S-OFDM (hereinafter also referred to as scheme B). It becomes transmission. As a result, when transmission is performed at 23 dBm, the reception device has an appropriate reception power. Therefore, the characteristic degradation is 2 dB in the former and 7 dB in the latter.

  Usually, in order to obtain a predetermined quality, the transmission power increases as the number of RBs used increases regardless of the modulation scheme. When the base station apparatus 2 designates the RB used by the terminal apparatus 1b-i, it is difficult to completely grasp whether or not the transmission power required by the terminal has reached the maximum value. Such a state cannot be dealt with by adaptive modulation. Then, the probability of packet loss (error) is very high especially in non-continuous transmission.

  Next, a characteristic difference between contiguous DFT-S-OFDM and Clipped DFT-S-OFDM (hereinafter also referred to as scheme C) will be considered. However, this is a case where turbo equalization is used for the receiving apparatus.

Under certain conditions, the characteristics of method A and method C are compared with a constant transmission power. When the modulation scheme is QPSK and the coding rate is ½, scheme C is added to achieve the same packet error rate as scheme A, and the necessary transmission power is calculated in the simulation.
According to the simulation results, the method C is about 0.1 dB when the clipping rate is 12.5%, about 1 dB when the clipping rate is 25%, and about 3 dB when the clipping rate is 37.5%. An additional transmission power of about 3.5 dB is required. Here, the clipping rate is a ratio of how many frequency resources are not transmitted, assuming that the frequency resource in the case of no clipping is 1.

  In the case of method C, it is expected that a larger MPR than that in method A is required, but as long as RBs to be used after clipping are continuous, it is considered that the MPR may be smaller than that in method B. Here, for the sake of simplicity, the MPR required for method C is 4 dB.

  As described above, when switching between method B and method C in a state where a transmission power of 23 dBm is required, considering the deterioration of the packet error rate due to clipping and MPR, the amount of power deficient in the receiver is The values are shown in Table 2 below. Note that the numerical value following the method C is the clipping ratio.

  Table 2 shows that when the clipping ratio is other than 37.5%, the reception power in the receiving apparatus is higher and the packet loss is lower when clipping is performed by method C than when all RBs are transmitted by method B.

  Next, similarly to FIG. 3 shown in the first embodiment, the operation of the RB selection unit 120b of this embodiment and the transmission signal will be described using FIG. FIG. 6 is a diagram for explaining the operation of the RB selection unit 120b and the transmission signal of the second embodiment.

  In the figure, a rectangular frame indicates RB, and the hatched portion indicates a subcarrier. One RB includes 4 subcarriers. In the figure, the total number of usable RBs is 10, and all are double clusters.

  FIG. 6A shows the position on the frequency axis of the RB designated by the base station apparatus 2. In the figure, the horizontal axis represents frequency and the vertical axis represents amplitude. In the upper part of FIG. 6A, it is shown that five RBs are designated for the cluster C61 and three RBs are designated for the cluster C62. 6A shows that six RBs are designated for cluster C63 and two RBs are designated for cluster C64. Further, in the lower part of FIG. 6A, it is shown that seven RBs are designated for the cluster C65 and one RB is designated for the cluster C66.

  When clipping is performed, the clipping rates are 37.5 (= 3/8 × 100)%, 25 (= 2/8 × 100)%, 12.5 (= 1/8 × 100)% in order from the top. It is.

  FIG. 6B shows the position on the frequency axis of the subcarrier to be actually transmitted. In the figure, the horizontal axis represents frequency and the vertical axis represents amplitude. FIG. 6B shows a subcarrier to which a transmission signal generated by the signal removal unit 105 is assigned. That is, except for the upper stage where the clipping ratio is the clipping threshold of 37.5%, the subcarriers of the cluster with a small number of RBs included in the cluster are clipped.

The process of determining whether to perform this clipping will be described below using an example.
For example, the processing of the RB selection unit 120b will be described in the case where the configuration of the cluster designated by the base station apparatus 2 is the middle stage in FIG. Here, consider a case where the transmission power calculated based on the transmission power control is the same as the maximum transmission power of 23 dBm. The RB selection unit 120b calculates a clipping ratio of 25% because six RBs are designated in the cluster C63 and two RBs are designated in the cluster C64.

First, the power shortage when clipping is performed is calculated.
Since method C will be used, MPR is 4 dB. Further, the degradation when clipping is performed is 1 dB as shown in Table 2. Therefore, when the method C is used, the power shortage is 5 dB.

  On the other hand, when the double cluster method B is used, the MPR is 7 dB, and the insufficient power in this case is 7 dB.

  Then, the RB selection unit 120b selects a method C having a shortage of insufficient power among the methods B and C. Then, the RB selection unit 120b selects the subcarrier of the cluster C63 as a used subcarrier used for transmission.

That is, the RB selection unit 120b includes the number of frequency components of resource blocks to which signals can be allocated (or the total frequency band obtained by adding the frequency bands of each cluster) and the number of frequency components of resource blocks included in each cluster ( Alternatively, the clipping ratio is calculated based on the frequency band of each cluster), the calculated clipping ratio (minimum value of the RB occupancy ratio), the acquired transmission power, and a predetermined maximum transmission power reduction amount (MPR). Based on the above, the used frequency resource block is selected.
In other words, the RB selection unit 120b acquires the transmission power designated from the base station device 2, and the number of frequency components of the resource block, the number of frequency components of the resource block included in each cluster, and the acquired transmission power The used frequency resource block is selected based on a predetermined reduction amount of the maximum transmission power.

As a result, when the clipping ratio is low, the RB selection unit 120b selects the method C with a small amount of insufficient power, thereby reducing the number of clusters and suppressing out-of-band radiation more than the method B. The packet error rate can be lowered than B.
In the above example, the case where the power density per RB is different before and after clipping is shown, but a method in which the power density per RB is not changed can also be used.
In this case, 1.2 dB, which is a shortage of power, is further added to the system C, which is 6.2 dB. Therefore, even in a method in which the amount of power per RB is not changed, in this example, the method C is selected by the RB selection unit 120b.

<Third Embodiment>
Subsequently, a third embodiment will be described. FIG. 7 is a schematic diagram illustrating a configuration of a wireless communication system 10c according to the third embodiment. The configuration of the wireless communication system 10c in the third embodiment is that each terminal device 1b-i of the wireless communication system 10b in the second embodiment of FIG. 4 is changed to a terminal device 1c-i, and the base station device 2 is The base station apparatus 2c is changed.

The base station device 2c has the same function as the base station 2 of the first embodiment, but differs in the following points. The base station device 2c transmits a signal including use-prohibited RB information indicating an RB prohibited from being used for data transmission to each terminal device 1c-i periodically or uniformly.
When each terminal apparatus 1c-i receives a signal including use-prohibited RB information transmitted from the base station apparatus 2c, that is, notifies the base station apparatus 2c that a predetermined RB is prohibited during data transmission. If so, the signal assigned to the RB is clipped and transmitted.

FIG. 8 is a schematic block diagram showing the configuration of the terminal device 1c-i in the third embodiment.
Here, the terminal device 1c-i (FIG. 8) according to the present embodiment is obtained by changing the transmission unit 140b to the transmission unit 140c with respect to the terminal device 1b-i (FIG. 5) according to the second embodiment. It has become. Specifically, the transmission signal generation unit 130b is changed to the transmission signal generation unit 130c, the signal removal unit 105b is changed to the signal removal unit 105c, and the RB selection unit 120b is changed to the RB selection unit (frequency band selection unit) 120c. It has become. In addition, the same code | symbol is attached | subjected to the function part which has the same function as the terminal device 1b-i (FIG. 5) of 2nd Embodiment, and the description is abbreviate | omitted.

The reception antenna unit 112 receives a signal including use-prohibited RB information transmitted from the base station apparatus 2 c and outputs the signal to the radio unit 113. Radio section 113 converts the signal including use-prohibited RB information input from reception antenna section 112 into a band that can be digitally processed, and then outputs the signal including converted use-prohibited RB information to A / D conversion section 114. . A / D conversion section 114 converts a signal including use-disabled RB information after conversion input from radio section 113 into a digital signal, and outputs the converted digital signal to reception section 115.
Then, the reception unit 115 demodulates the digital signal input from the A / D conversion unit 114, and outputs the use prohibition RB information obtained by the demodulation to the RB selection unit 120c.

The RB selection unit 120c of the present embodiment has the same function as that of the RB selection unit 120b of the second embodiment, but the following functions are further added.
The RB selection unit 120 c holds the use prohibition RB information input from the reception unit 115.
Then, the RB selection unit 120c reads the use prohibition RB information held by itself, generates clipping information C indicating an instruction to clip the RB indicated by the read use prohibition RB information, and generates the generated clipping information C as a signal. Output to the removal unit 105.

  Note that the use-prohibited RB information is not notified from the base station device 2c, but may be held in advance by the terminal device 1c-i. In this case, the RB selection unit 120 c reads out use-prohibited RB information indicating an RB that is prohibited from being used for data transmission, and outputs the read-out prohibition RB information to the signal removal unit 105. Further, the use prohibition RB information may be notified from another device that is not directly connected.

  When a plurality of subcarriers designated by the base station apparatus 2c include subcarriers that are prohibited from being used, the transmission signal generation unit 130c includes subcarriers other than subcarriers that are prohibited from being used. A transmission signal in which a signal is arranged with respect to a carrier is generated.

  The signal removal unit 105c removes the use-prohibited RB signal indicated by the clipping information C input from the RB selection unit 120c from the signals input from the subcarrier mapping unit 104. The signal removal unit 105c outputs the signal after removal to the IFFT unit 106 as a transmission signal.

Next, similarly to FIG. 3 shown in the first embodiment, the operation of the RB selection unit 120c of this embodiment and the transmission signal will be described using FIG. FIG. 9 is a diagram for explaining the operation of the RB selection unit 120c and the transmission signal of the third embodiment.
In the figure, a rectangular frame indicates RB, and a hatched portion indicates a subcarrier. One RB includes 4 subcarriers. Also, in the figure, the total number of usable RBs is 8, and the case where the upper stage is a double cluster and the lower stage is a single cluster is shown.

Further, in the figure, a broken-line square frame indicates the use prohibition RB. In the figure, the use of the sixth and seventh RBs from the left is prohibited.
FIG. 9A shows the position on the frequency axis of the RB designated by the base station apparatus 2c. In the figure, the horizontal axis represents frequency and the vertical axis represents amplitude. In the upper part of FIG. 9A, it is shown that four RBs are designated for the cluster C91 and two RBs are designated for the cluster C92. In the lower part of FIG. 9B, it is shown that six RBs are designated consecutively in the cluster C93.

  FIG. 4B shows the position on the frequency axis of the spectrum (subcarrier) to be actually transmitted. In the figure, the horizontal axis represents frequency and the vertical axis represents amplitude. In the upper part of the figure, it is shown that a part of the cluster C92 is clipped. In the lower part of the figure, it is shown that a part of continuous RBs included in the cluster C93 is clipped. The clipped subcarrier is shown in white.

  As described above, the terminal device 1c-i connected to the base station device 2c obtains the use prohibition RB information indicating the RB that should not be used for transmission, and performs clipping of the RB indicated by the use prohibition RB information. Thereby, the base station apparatus 2c can ensure the frequency area | region where a signal is not transmitted within a system band, without adding a different process to the process so far.

  In this embodiment, the case where the frequency for which use is prohibited is defined in units of RBs has been described. However, the frequency for which use is prohibited is defined in units of RB groups (RBGs) in which a plurality of RBs are bundled even in units of subcarriers. It may be defined.

In addition, the base station apparatus 2c may calculate a frequency for which use is prohibited for each user ID using, for example, a user ID for identifying a user who operates the terminal apparatus 1c-i. A specific example will be described below. Here, the _{N ID} X is a user ID (X is an integer of 2 or more) the remainder when divided by the _{N ID_X,} a number assigned in sequence for identifying the RB is referred to as RB index. At this time, the base station apparatus 2c sets the start position of the RB index to be prohibited to be n × X + N _{ID_X} and _sets the end position of the RB index to be prohibited to be (n + 1) × X + N _{ID_X} −1. Thereby, the base station apparatus 2c may calculate the RB to be prohibited for each user ID. Here, n is an arbitrary integer, and it is necessary to set a common value between the base station device 2c and the terminal device 1c-i in advance.

  The base station apparatus 2c may designate the start position of the RB index to be prohibited and the end position of the RB index to be prohibited as the use prohibited RB. Thereby, the base station apparatus 2c can divide users into n × X groups and designate the use prohibition RB.

As described above, the terminal device 1c-i of the present embodiment is prohibited from being used when a plurality of RBs designated by the base station device 2c include RBs that are prohibited from being used. And the signal after the removal is generated as a transmission signal.
That is, when a plurality of subcarriers designated by the base station include a frequency band that is prohibited from being used, the transmitting unit 140c uses a frequency band other than the frequency band that is prohibited from being used. On the other hand, a transmission signal in which the signal is arranged is transmitted.
As a result, the base station device 2c uses the frequency band of the RB that is prohibited from being used, the usage band of another terminal device, the usage band of a relay station installed in the service area of the base station device 2c, or In other words, it is possible to assign to a use band of the base station apparatus 2c arranged so as to increase the frequency use efficiency, such as a so-called pico cell. As a result, the base station device 2c can effectively use the frequency band. Moreover, the base station apparatus 2c can raise a throughput by assigning a frequency domain to a pico cell.

<Fourth Embodiment>
Subsequently, a fourth embodiment will be described. FIG. 10 is a schematic diagram illustrating a configuration of a wireless communication system 10d according to the fourth embodiment. The configuration of the wireless communication system 10d in the fourth embodiment is such that the base station device 2c of the wireless communication system 10c in the third embodiment of FIG. 7 is changed to the base station device 2d.

The configuration of the wireless communication system 10d in the fourth embodiment is the same as the configuration of the wireless communication system 10c in the third embodiment, but differs in the following points.
The base station apparatus 2d of the present embodiment receives the transmission signal after clipping transmitted from the terminal apparatus 1c-i, and improves reception characteristics using a turbo equalization technique.

  FIG. 11 is a schematic block diagram illustrating the configuration of the base station device 2d according to the fourth embodiment. The base station device 2d includes a reception device 230, a control device 240, a transmission unit 220, a D / A conversion unit 221, a radio unit 222, and a transmission antenna 223. Receiving device 230 includes receiving antenna section 200, radio section 201, A / D conversion section 202, synchronization section 203, CP removal section 204, S / P conversion section 205, FFT section 206, subcarrier demapping section 207, and cancellation section. 209, an equalization unit 210, a demodulation / error correction decoding unit 211, a determination unit 213, a propagation path estimation unit 214, a propagation path multiplication unit 216, a DFT unit 217, and a replica generation unit 218. The control device 240 includes a scheduling unit 219.

The receiving antenna unit 200 receives a signal transmitted from the terminal device 1c-i or the terminal device 12c, and outputs the received signal to the wireless unit 201.
Radio section 201 receives a signal from reception antenna section 200, converts the input signal to a frequency that can be A / D converted, and outputs the converted signal to A / D conversion section 202.
The A / D conversion unit 202 converts the signal input from the wireless unit 201 from an analog signal to a digital signal, and outputs the digital signal obtained by the conversion to the synchronization unit 203.

The synchronization unit 203 receives the digital signal input from the A / D conversion unit 202, establishes symbol synchronization for the input digital signal, and outputs the signal after the symbol synchronization is established to the CP removal unit 204. .
CP removal section 204 removes the CP for each symbol from the signal input from synchronization section 203 and outputs the signal after CP removal to S / P conversion section 205.

The S / P conversion unit 205 converts the signal input from the CP removal unit 204 from a serial signal to a parallel signal, and outputs the converted parallel signal to the FFT unit 206.
The FFT unit 206 performs fast Fourier transform on the parallel signal input from the S / P conversion unit 205 to convert the time domain signal into a frequency domain signal, and converts the frequency domain parallel signal obtained by the conversion into a subcarrier. Output to the demapping unit 207.

The scheduling determined by the scheduling unit 219 for the current transmission is input from the scheduling unit 219 and the parallel signal is input from the FFT unit 206 to the subcarrier demapping unit 207.
The subcarrier demapping unit 207 separates the input parallel signal in the frequency domain into signals for each user according to the input scheduling.

Here, when clipping is performed in the terminal device 1c-i, noise is input to the subcarrier. However, if the base station device 2d knows in advance the clipped subcarrier of the terminal device 1c-i, the subcarrier demapping unit 207 generates a signal after zero insertion by substituting 0 into the signal for each user. To do. Thereby, subcarrier demapping section 207 removes the noise superimposed on the clipped subcarrier, so that the reception characteristics can be improved. Subcarrier demapping section 207 outputs signal U after zero insertion to cancellation section 209.
Further, subcarrier demapping section 207 extracts pilot signal P for propagation path estimation from the frequency domain parallel signal, and outputs the extracted pilot signal P to propagation path estimation section 214. Subsequent signal processing is performed for each user's received signal.

Propagation path estimation section 214 calculates propagation path estimation value CE using pilot signal P input from subcarrier demapping section 207. As described above, when the base station apparatus 2d holds the clipping information C, the propagation path estimation unit 214 substitutes 0 for the propagation path estimation value CE corresponding to the subcarrier for which clipping has been performed. As a result, the characteristics indicated by the propagation path estimation value CE can be improved.
The propagation path estimation unit 214 outputs the propagation path estimation value CE after zero insertion to the equalization unit 210, the propagation path multiplication unit 216, and the scheduling unit 219.

The propagation path multiplication unit 216 multiplies the replica signal input from the DFT unit 217 by the propagation path estimation value CE input from the propagation path estimation unit 214 to generate a reception replica. The propagation path multiplication unit 216 outputs the generated reception replica to the cancellation unit 209.
Here, the frequency domain replica signal is converted from a time domain signal to a frequency domain signal by the DFT unit 217 in the course of frequency domain SC / MMSE (Soft Cellular with Minimum Mean Square Filter) turbo equalization processing. It has been converted.

  The cancel unit 209 calculates the residual component R by subtracting (canceling) the reception replica input from the propagation path multiplication unit 215 from the signal U input from the subcarrier demapping 207. The cancel unit 209 outputs the calculated residual component R to the equalization unit 210. However, since the cancel unit 209 does not generate a replica of the desired signal in the first process, the cancel unit 209 does not perform the cancel process and outputs the signal U input from the subcarrier demapping 207 to the equalization unit 210 as it is.

Thus, in the frequency domain SC / MMSE turbo equalization used by the base station apparatus 2d of the present embodiment, the cancel unit 209 temporarily cancels the replica of the desired signal and calculates the residual signal component.
The reason why the cancel unit 209 calculates the residual signal component is to reduce the amount of calculation. This is because the equalization unit 210, which will be described later, performs an inverse matrix operation, so that if the cancellation and equalization are repeated leaving only the replica of the desired signal, the replica of the desired signal contained in the block is the inverse matrix for the number of repetitions. This is because computation is performed and the amount of computation increases.

  The equalization unit 210 uses the residual component input from the cancellation unit 209, the propagation path estimation value CE of the desired signal input from the propagation path estimation unit 214, and the desired signal replica input from the replica generation unit 218. Signal equalization. Specifically, the equalization unit 210 calculates the optimal weight from the residual component, the propagation path estimation value, and a replica of the desired signal, and the final time-equalized signal multiplied by the optimal weight is obtained. The data is output to the demodulation / error correction decoding unit 211.

  However, in the case of the first process, since the replica of the desired signal is not input from the replica generation unit 218, the equalization unit 210 does not cancel. This is equivalent to the conventional MMSE (Minimum Mean Squared Error) equalization. Thus, the base station apparatus 2d in the present embodiment performs equalization by treating the spectrum clipped on the transmission side as if it was missing due to a drop in the propagation path. By doing so, the base station device 2d can correctly reproduce the signal that should be transmitted (the signal before clipping on the transmission side).

The demodulation / error correction decoding unit 211 performs demodulation and error correction on the signal input from the equalization unit 210, and the log likelihood of the sign bit with improved reliability with respect to the signal after error correction obtained thereby. The ratio (LLR: Log Likelihood Ratio) is calculated, and the calculated LLR and the signal after error correction are output to the replica generation unit 218.
Demodulation / error correction decoding section 211 repeats demodulation and error correction processing a predetermined number of times, and then outputs an error-corrected signal obtained after the repetition to determination section 213.

The replica generation unit 218 generates a “replica of desired signal” which is a soft replica proportional to the reliability in accordance with the LLR input from the demodulation / error correction decoding unit 211.
Further, the replica generation unit 218 outputs the generated replica of the desired signal to the DFT unit 217 so that the cancellation unit 209 cancels the desired frequency signal once. Further, the replica generation unit 218 outputs a replica of the desired signal to the equalization unit 210 in order to reconstruct the desired signal at the time of equalization. Thereby, the amount of calculation accompanying an inverse matrix calculation can be reduced because the equalization part 210 reconfigure | reconstructs a signal.

In this way, the base station device 2d repeats the processing of the cancel unit 209 to the demodulation / error correction decoding unit 211 and the propagation path multiplication unit 216 to the replica generation unit 218, thereby gradually increasing the reliability of the code bit. Can be obtained.
The determination unit 213 receives the error-corrected signal from the demodulation / error correction decoding unit 211 after repeating the above process a predetermined number of times. The determination unit 213 performs a hard decision on the input error-corrected signal and extracts decoded data. Then, the determination unit 213 outputs the extracted decoded data to the signal processing unit (not shown) of the base station device 2d as reception data RD.

The scheduling unit 219 outputs mapping information, which is information indicating the RB assigned to each terminal device 1c-i, and the number of assigned RBs to the transmission unit 220.
The transmission unit 220 generates a transmission signal by performing error correction encoding and modulation on the transmission data TD2, the mapping information, and the number of assigned RBs to be transmitted to each terminal device, and the generated transmission signal is D / A The data is output to the conversion unit 221.
The D / A conversion unit 221 converts the transmission signal input from the transmission unit 220 from a digital signal to an analog signal, and outputs the converted analog signal to the radio unit 222.
The radio unit 222 up-converts the analog signal input from the D / A conversion unit 221 to a radio frequency, and transmits the up-converted signal to the terminal device 1c-i via the transmission antenna 223.

  As described above, the base station device 2d according to the present embodiment separates the received signal into signals for each user, and generates a signal after zero insertion in which 0 is substituted for the clipped frequency signal. As a result, the base station apparatus 2d can remove noise superimposed on the clipped subcarrier, and thus can improve reception characteristics.

Note that the base station apparatus 2d of the present embodiment may perform the repetition process only for the signal of the terminal apparatus 1c-i that performs clipping. Thereby, the base station apparatus 2d can prevent a processing delay due to repeated processing and reduce power consumption without degrading characteristics.
Moreover, although the radio | wireless communications system 10d of this embodiment demonstrated the structure provided with the terminal device 1c-i, it replaced with the terminal device 1c-i not only this but the terminal device 1-i in 1st Embodiment. Or the structure provided with the terminal device 1b-i in 2nd Embodiment may be sufficient.

<Fifth Embodiment>
Subsequently, a fifth embodiment will be described. In the embodiments so far, a method of clipping a part of a DFT signal on the assumption of a non-continuous DFT-S-OFDM signal as shown in FIG. 2 has been shown. On the other hand, this embodiment demonstrates the case where a several DFT-S-OFDM signal is transmitted simultaneously using a different system band. Here, the system band corresponds to a component carrier or a band.
In the present embodiment, one DFT-S-OFDM signal is considered to include both contiguous and non-continuous.

  Here, a communication scheme for simultaneously transmitting a plurality of DFT-S-OFDM signals is referred to as NxDFT-S-OFDM. In LTE, in particular, DFT-S-OFDM signals are regarded as one system band, and transmitting a plurality of DFT-S-OFDM signals simultaneously in different system bands is called carrier aggregation.

FIG. 12 is a schematic diagram illustrating a configuration of a wireless communication system 10e according to the fifth embodiment. The configuration of the wireless communication system 10e in the fifth embodiment is such that the terminal devices 1-1, ..., 1-N of the wireless communication system 10 in the first embodiment of FIG. The base station apparatus 2 is changed to the base station apparatus 2e.
The base station apparatus 2e of this embodiment has the same function as the base station apparatus 2 of the first embodiment, but differs in the following points. The base station apparatus 2e of this embodiment notifies each terminal apparatus 1e-i that transmission signals are transmitted in a plurality of system bands.
The terminal device 1e-i of the present embodiment has the same function as the terminal device 1-i of the first embodiment, but differs in the following points. The terminal device 1e-i of the present embodiment switches between transmission of an NxDFT-S-OFDM signal and transmission of one DFT-S-OFDM signal.

  FIG. 13 is a schematic block diagram showing the configuration of the terminal device 1e-i in the fifth embodiment. Here, the blocks having the same functions as those in FIG. Moreover,-(hyphen) indicates that there are a plurality of blocks having the same function. In the terminal device 1e-i, the transmission device 116 is changed to the transmission device 116e with respect to the terminal device 1-i in the first embodiment. More specifically, in the terminal device 1e-i, the data generation unit 150-2 is added to the terminal device 1-i in the first embodiment, the wireless unit 110 is added to the wireless unit 110e, and the RB selection unit 120 is added. Is changed to an RB control unit (resource block control unit) 120e.

Here, each data generation unit 150-j (j is 1 or 2) includes an encoding unit 100-j, a modulation unit 101-j, an S / P conversion unit 102-j, a DFT unit 103-j, Subcarrier mapping section 104-j, signal removal section 105-j, IFFT section 106-j, P / S conversion section 107-j, CP insertion section 108-j, and D / A conversion section 109-j With.
Moreover, the transmission signal generation unit 130e includes a subcarrier mapping unit 104-1, a subcarrier mapping unit 104-2, a signal removal unit 105-1, and a signal removal unit 105-2.

  The transmission unit 140e includes subcarrier mapping units 104-1 and 104-2, signal removal units 105-1 and 105-2, IFFT units 106-1 and 106-2, and a P / S conversion unit 107-. 1, 107-2, CP insertion sections 108-1, 108-2, D / A conversion sections 109-1, 109-2, radio section 110e, transmission antenna section 111, and RB control section 120e. Prepare.

  In this embodiment, in order to simplify the description, the maximum number of DFT-S-OFDM signals that can be transmitted simultaneously is set to 2 as an example. Note that the terminal device 1e-i may set the maximum number of DFT-S-OFDM signals that can be transmitted simultaneously to three or more. In that case, the terminal device 1e-i may include the same number of data generation units as the maximum number of transmissions.

Radio section 110e combines DFT-S-OFDM signals respectively input from D / A conversion section 109-1 and D / A conversion section 109-2. Radio section 110e then up-converts the synthesized signal after synthesis into a radio frequency band signal, and transmits the up-converted signal from transmission antenna section 111.
In the present embodiment, the example in which the radio unit 110e combines analog signals by analog signal processing has been described. However, the present invention is not limited to this, and a processing unit capable of digital processing before D / A conversion (for example, a CP insertion unit) 108-1) may synthesize the DFT-S-OFDM signal.

The RB control unit 120e is notified by the base station device that transmission signals are transmitted in a plurality of system bands, and when the total transmission power necessary for transmission exceeds a predetermined value, the RB control unit 120e transmits signals in at least one system band. Clip everything. In addition, the RB control unit 120e controls the subcarrier mapping units 104-1 and 104-2 and the signal removal units 105-1 and 105-2. Here, the predetermined value is determined based on MPR.
The transmission signal generation unit 130e generates a transmission signal in which signals are arranged for subcarriers in the system band that the RB control unit 120e does not target for clipping.

<Details of Processing of RB Control Unit 120e>
Hereinafter, the details of the processing of the RB control unit 120e will be described. First, as a premise, since NxDFT-S-OFDM has a spectrum arranged at a distant frequency, it is necessary for Dx-S-OFDM and NxDFT-S-OFDM as in the second embodiment. Different MPRs. For example, the MPR of DFT-S-OFDM is 2 dB, and the MPR of NxDFT-S-OFDM is 5 dB. In this case, the maximum transmission power of the terminal device 1e-i is set to 23 dBm, and as a result of performing transmission power control, the terminal device 1e-i is assumed to transmit data with the transmission power of 23 dBm as an example. The process of 120e will be described.

<Example using method E>
In this case, since the above-described MPR is set, in transmission of DFT-S-OFDM (hereinafter also referred to as scheme A), transmission power is transmission at 21 dBm. On the other hand, in transmission of NxDFT-S-OFDM (hereinafter also referred to as scheme D), transmission power is 18 dBm. In that case, when the transmission is originally performed at 23 dBm, the reception device has an appropriate reception power, so that the characteristic degradation is 2 dB in the former and 5 dB in the latter.

In NxDFT-S-OFDM, the signal removal units 105-1 and 105-2 clip all signals. Hereinafter, this method is referred to as a method E. Under this premise, the data transmitted by the clipped DFT-S-OFDM signal cannot be transmitted. However, since the signal not clipped can use power up to 21 dBm, the terminal device 1e-i has the characteristics. Deterioration can be prevented.
In addition, although the signal removal part 105-1 or the signal removal part 105-2 showed the example which clips all signals on a circuit structure, the radio | wireless part 110e may turn off one signal.

  The RB control unit 120e performs switching between the method D and the method E using a predetermined transmission power as a reference power. Specifically, for example, the RB control unit 120e previously holds, as a reference power, a power (for example, 18 dBm) obtained by subtracting an NxDFT-S-OFDM MPR (for example, 5 dBm) from a maximum transmission power (for example, 23 dBm). . Then, the RB control unit 120e switches to the method E when the transmission power is larger than the reference power. On the other hand, the RB control unit 120e switches to the method D when the transmission power is equal to or lower than the reference power.

Thereby, the RB control unit 120e selects the method E when the transmission power is larger than the reference power. Then, the RB control unit 120e controls the signal removal unit 105-1 or 105-2 so as to clip all one signals. Thereby, the RB control unit 120e can decrease the packet error rate by increasing the transmission power.
On the other hand, the RB control unit 120e selects the method D when the transmission power is equal to or lower than the reference power. Then, the RB control unit 120e controls the signal removal units 105-1 and 105-2 to transmit two DFT-S-OFDM signals simultaneously.

Further, when there are three or more DFT-S-OFDM signals, the RB control unit 120e preferentially turns off the DFT-S-OFDM signal having a low required transmission power. Furthermore, when it is necessary to turn off a plurality of DFT-S-OFDM signals, the RB control unit 120e sequentially turns off the DFT-S-OFDM signals having the low required transmission power, and similarly, packet errors The rate can be lowered.
Note that the RB control unit 120e may perform the signal removal unit 105-1 or 105-2 so as to clip other than the DFT-S-OFDM signal on which control information necessary for the system is superimposed.

<Example using method F>
However, if the RB control unit 120e clips (turns off) all transmissions of DFT-S-OFDM, the transmission rate deteriorates. Therefore, the RB control unit 120e may use the method F that does not involve a decrease in transmission rate as described below.

In method F, each part of terminal device 1e-1 has the same function as in method E, but differs in the following points.
The RB control unit 120e causes the signal removal unit 105-1 or 105-2 to clip so that the number of subcarriers used in other system bands is the number of subcarriers specified by the base station device 2e.
Then, the RB control unit 120e transmits the data clipped by the signal removal unit 105-1 or 105-2 in another system band.

For simplicity of explanation, when two DFT-S-OFDM signals are transmitted, the number of RBs is N in the first DFT-S-OFDM signal, which is one of them, and the other second signal is transmitted. In the case of the DFT-S-OFDM signal, an example in which the number of RBs is M will be described.
As in the previous example, the RB control unit 120e clips all of the first DFT-S-OFDM signals, but superimposes the corresponding data on the second DFT-S-OFDM.

In FIG. 13, when a certain encoding unit (100-1 or 100-2) superimposes data encoded by another encoding unit (100-1 or 100-2) on data encoded by itself, As it is, the number of RBs specified by the base station device 2e is insufficient. Therefore, the RB control unit 120e removes (clips) data by the number of insufficient RBs. Hereinafter, this method is referred to as method F. In this example, the clipping ratio is N / (N + M).
By performing such processing, the terminal device 1e-i can suppress the MPR without degrading the communication rate, and thus the transmission power of the terminal device 1e-i can be increased. Thereby, the terminal device 1e-i can lower the packet error rate without deteriorating the communication rate.

  Since the performance degradation is smaller when clipping the smaller number of RBs M and N, the signal removal units 105-1 and 105-2 remove the data with the smaller number of RBs. Specifically, the RB control unit 120e transmits the transmission input to any data generation unit 150-j based on the number of RBs (for example, M, N) allocated to each data generation unit 150-j. Decide whether to remove the data.

  When it is determined that the transmission data input to the data generation unit 150-1 is to be removed, the RB control unit 120e outputs that fact to the encoding unit 100-1. On the other hand, when it is determined that the transmission data input to the data generation unit 150-2 is to be removed, the RB control unit 120e outputs that fact to the encoding unit 100-2.

  Furthermore, if the characteristics are mentioned, the RB control unit 120e uses the method E without reducing the communication rate if the total amount of performance degradation due to the MPR of the method F and clipping is smaller than the MPR of the method D. Therefore, communication with higher performance than that of method D can be realized.

  In the above-mentioned method F, it is assumed that the modulation method and coding rate used in the two DFT-S-OFDM signals are the same, but when they are different, the clipping rate is simply N / ( N + M), the RB control unit 120e may determine the clipping rate in consideration of them.

Further, the RB control unit 120e may not use the scheme E when the designated modulation scheme and coding rate are different.
Further, there is a method (hereinafter, method G) in which the transmission power is reduced on average when the transmission power required for the terminal exceeds the maximum transmission power of the terminal. The transmission unit 140e may calculate an error rate assumed in the scheme F and the scheme G for each packet, and select a scheme with good characteristics from these schemes.

<Application example to carrier aggregation in LTE>
As described above, LTE employs a system called carrier aggregation. When the number of system bands that can be carrier-aggregated and the number of DFT-S-OFDMs that can be transmitted simultaneously by the transmission apparatus are different, the transmission unit 140e may take a scheme G as shown below.

In method G, each unit of terminal device 1e-1 has the same function as in method E, but differs in the following points.
The RB control unit 120e is notified by the base station apparatus that transmission signals are transmitted in a plurality of system bands, and clips all signals in at least one system band according to the positional relationship of the system bands used for transmission. . Here, the positional relationship of the system bands used for transmission is whether or not the used system bands are continuous in the frequency domain.
Then, the transmission signal generation unit 130e generates a transmission signal in which signals are arranged for subcarriers in the system band that the resource block control unit does not target for clipping.

FIG. 14 is a diagram for explaining processing of the transmission unit 140e when the number of system bands and the number of DFT-S-OFDMs that can be transmitted simultaneously by the transmission apparatus are different.
FIG. 14A shows a case where there are four usable system bands. In the figure, system bands B14-1 to B14-4 are shown.

  FIG. 14B shows a case where the transmission apparatus transmits a DFT-S-OFDM signal in two continuous system bands. In the figure, system bands B14-1 to B14-4 are shown. The DFT-OFDM signal S14-5 is a signal in the system band B14-2, and the DFT-OFDM signal S14-6 is a signal in the system band B14-3. That is, the DFT-OFDM signal S14-5 and the DFT-OFDM signal S14-6 are assigned to a continuous system band.

  FIG. 14C shows a case where a DFT-S-OFDM signal is transmitted in a discontinuous system band. In the figure, system bands B14-1 to B14-4 are shown. The DFT-OFDM signal S14-7 is a signal in the system band B14-2, and the DFT-OFDM signal S14-8 is a signal in the system band B14-4. That is, the DFT-OFDM signal S14-7 and the DFT-OFDM signal S14-8 are allocated to the discontinuous system band.

  In general, when a plurality of DFT-S-OFDM signals are allocated to a discontinuous system band as shown in FIG. 14C, a plurality of DFT-S-OFDM signals are assigned as shown in FIG. The MPR to be considered is larger than when it is assigned to a continuous system band.

In view of this, when the required transmission power required for transmission exceeds a predetermined value and the signal position to be transmitted in the continuous system band is designated (in the case of the first condition), On the other hand, when the required transmission power required for transmission exceeds a predetermined value and the RB control unit 120e is designated to transmit a DFT-S-OFDM signal in a discontinuous system band ( In the case of the second condition), since the MPR becomes larger than that in the case of the first condition, the system is switched to the system E or the system F.
Thereby, the RB control unit 120e can switch the method while suppressing out-of-band radiation, and can reduce the packet error rate.

When the terminal device 1e-i transmits a DFT-S-OFDM signal in a discontinuous system band as shown in FIG. 14C, the RB control unit 120e Regardless of the required transmission power, method E or F may be used.
Further, when there are three or more DFT-S-OFDM signals to be transmitted, the RB control unit 120e clips in order from the DFT-S-OFDM signals allocated to the outer system band until the required transmission power can be secured. It may be. Accordingly, the RB control unit 120e clips the DFT-S-OFDM signal because the required transmission power can be ensured while suppressing out-of-band radiation even when transmitting three or more DFT-S-OFDM signals. Packet error rate can be reduced.

<Effect>
The terminal device (1-i, 1b-i, or 1c-i) of each embodiment of the present invention is based on the configuration of subcarriers in the frequency domain specified by the base station device (2, 2c, or 2d). -Switch between the contiguous DFT-S-OFDM system and the Clipped DFT-S-OFDM system.
Specifically, the terminal device (1-i, 1b-i, or 1c-i) has the highest number of subcarriers included in the cluster with respect to the total number of subcarriers designated by the base station device (2, 2c, or 2d). A clipping ratio that is a ratio of the number of subcarriers included in a small cluster is calculated, and a subcarrier to be used is selected based on the calculated clipping ratio. The terminal apparatus (1-i, 1b-i, or 1c-i) transmits the signal assigned to the selected subcarrier as a transmission signal to the base station apparatus 2.

  Thereby, the terminal device (1-i, 1b-i, or 1c-i) allows the RB selection unit 120 to perform clipping within a range in which characteristic deterioration due to clipping is allowed when the clipping rate is smaller than a predetermined threshold. And reducing the number of clusters used for transmission, it is possible to reduce the influence of out-of-band radiation.

  Also, the terminal device 1b-i in the second embodiment acquires the transmission power specified from the base station device, and calculates the clipping rate based on the RB specified from the base station. The terminal device 1b-i selects a subcarrier to be used for transmission based on the calculated clipping rate, the designated transmission power, and a predetermined maximum transmission power reduction amount (MPR). Thereby, when the clipping ratio is small, the terminal apparatus 1b-i selects the Clipped DFT-S-OFDM system, so that the base station apparatus 2 can select the terminal apparatus 1b-i more than the non-continuous DFT-S-OFDM system. Since it is possible to increase the reception power when receiving a signal from the network, it is possible to reduce the packet error rate while suppressing the radiation outside the band.

Further, the terminal device 1c-i in the third embodiment is prohibited from use when a plurality of subcarriers designated by the base station device 2c include subcarriers prohibited from being used. A transmission signal in which signals are arranged for subcarriers other than the subcarriers being generated is generated.
As a result, the base station device 2c uses the frequency band of the RB that is prohibited from being used, the usage band of another terminal device, the usage band of a relay station installed in the service area of the base station device 2c, or In other words, it is possible to assign to a use band of the base station apparatus 2c arranged so as to increase the frequency use efficiency, such as a so-called pico cell. As a result, the base station device 2c can effectively use the frequency band.

  In addition, each terminal apparatus of each embodiment extracts all the clusters whose RB occupancy is lower than a predetermined threshold when three or more clusters are notified from the base station apparatus, and not only one cluster. The signals of all the extracted clusters may be deleted. Thereby, each terminal device can reduce the number of subcarriers concerning transmission.

In addition, each terminal device in each embodiment, when three or more clusters are notified from the base station device, clusters whose RB occupancy is lower than a predetermined threshold are those of clusters located at both ends on the frequency axis. Assume a case. In that case, each terminal device removes the signal of the end cluster excluded from the frequency band when the frequency band becomes narrower in the frequency band occupied by the cluster group other than the cluster at either end. May be.
As a result, each terminal device can narrow the frequency band for transmission within a range that can be decoded by the base station even if a signal of some frequencies is clipped. Can be suppressed.

Further, each terminal device assumes a case in which, when three or more clusters are notified from the base station device, clusters whose RB occupancy is lower than a predetermined threshold are located at both ends on the frequency axis. . In that case, each terminal device receives the signal of the end cluster when a wider frequency band is obtained among the frequency bands that are not used between the end cluster and the cluster closest to the cluster on the frequency axis. May be removed.
As a result, each terminal device can narrow the frequency band for transmission within a range that can be decoded by the base station even if a signal of some frequencies is clipped. Can be suppressed.

In addition, each terminal device of each embodiment has a frequency until a predetermined number of clusters out of a plurality of cluster signals or until a frequency band for transmission is equal to or lower than a predetermined frequency band. You may clip the signal of a cluster in an order from the cluster which becomes an outer side in a band. Thereby, each terminal device can narrow the frequency band concerning transmission.
In that case, each terminal apparatus may clip a cluster having a smaller number of RBs among the clusters on the outer side in the frequency band. As a result, a cluster signal having a large number of RBs can be left in a signal to be transmitted to the base station apparatus, so that the packet error rate in the base station apparatus can be reduced.

In addition, each terminal apparatus of each embodiment may clip a cluster signal having a frequency equal to or higher than a predetermined frequency or lower than a predetermined frequency among a plurality of cluster signals. Thereby, each terminal device can narrow the frequency band concerning transmission.
In addition, each terminal device of each embodiment alternately switches one cluster of the signals of the clusters at both ends in the frequency band among the signals of the plurality of clusters every time a predetermined unit time elapses. You may clip. Thereby, each terminal device can narrow the frequency band concerning transmission.

  In addition, each terminal device of each embodiment may clip an inner cluster signal among the cluster signals. Thereby, each terminal device can reduce the number of subcarriers concerning transmission. Moreover, although each terminal apparatus of each embodiment deleted the signal of the cluster in which the RB occupancy is minimum, the present invention is not limited to this, and the signal of any cluster may be deleted. Thereby, each terminal device can reduce the number of subcarriers concerning transmission.

  In each embodiment, the base station apparatus includes a control apparatus that performs scheduling and a receiving apparatus that receives the DFT-S-OFDM signal, and the terminal apparatus includes a transmitting apparatus that transmits the DFT-S-OFDM signal. As explained. However, the present invention is not limited to these configurations. For example, the base station device may include a control device and a transmission device, and the terminal device may include a reception device. In addition, the control device, the transmission device, and the reception device may be realized by separate devices. For example, the base station device may include a receiving device, the second base station device may include a control device, and the terminal device may include a receiving device.

  Moreover, in each embodiment, although it demonstrated that a terminal device processed for every frequency component (frequency RB) of a resource block, you may process for every subcarrier not only this. That is, the terminal device may perform processing for each predetermined unit frequency band.

  Further, in each embodiment, the RB selection unit (120, 120b, 120c) selects the used frequency resource block to be used for transmission based on the number of frequencies RB included in each cluster. is not. The RB selection unit (120, 120b, 120c) may select a use frequency bandwidth to be used for transmission based on the frequency bandwidth of each cluster.

  Specifically, the RB selection unit (120, 120b, 120c) uses the frequency band used for transmission based on the total frequency band obtained by summing up the frequency bands of the clusters and the frequency bands included in the clusters. May be selected. More specifically, the RB selection unit (120, 120b, 120c) calculates the clipping ratio based on the total frequency band obtained by summing up the frequency bands of the clusters and the frequency bands included in the clusters, and the calculation is performed. The used frequency band may be selected based on the clipping rate.

  At that time, the RB selection unit (120, 120b, 120c) calculates, for each cluster, an occupancy that is a ratio of the frequency bands included in the cluster to the total of the frequency bands included in each cluster, and the calculated The clipping ratio may be calculated based on the occupation ratio.

  In the second or third embodiment, the RB selection unit (120b, 120c) acquires the transmission power designated from the base station apparatus, and the frequency band of each cluster and the acquired transmission power are determined in advance. The used frequency band used for transmission may be selected based on the reduction amount of the maximum transmission power.

  More specifically, the RB selection unit (120b, 120c) calculates a clipping ratio based on the total frequency band obtained by summing up the frequency bands of the clusters and the frequency bands of the clusters, and the calculated clipping ratio. And a use frequency band to be used for transmission may be selected based on the acquired transmission power and a predetermined reduction amount of the maximum transmission power.

Further, the terminal device (1-i, 1b-i, 1c-i, or 1e-i) and the base station (2, 2c, 2d, or 2e) according to the present embodiment are realized as a processor, thereby realizing the terminal device. The above-described various processes relating to (1-i, 1b-i, 1c-i, or 1e-i) and the base station (2, 2c, 2d, or 2e) may be performed.
Specifically, for example, the processor acquires mapping information indicating that a plurality of sets of unit frequency bands whose positions on the frequency axis of the unit frequency bands are continuous on the frequency axis are allocated, and the acquired mapping Based on the information, some of the frequency bands indicated by the plurality of sets may be selected as unused sets that are not used for transmission.

  Further, a computer-readable recording of a program for executing each process of the terminal device (1-i, 1b-i, 1c-i, or 1e-i) and the base station (2, 2c, or 2d) of the present embodiment The terminal device (1-i, 1b-i, 1c-i, or 1e-i) and the base station (2) are recorded by recording the program on the medium and causing the computer system to read and execute the program recorded on the recording medium. The above-described various processes according to 2c, 2d, or 2e) may be performed.

  Here, the “computer system” may include an OS and hardware such as peripheral devices. Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used. The “computer-readable recording medium” means a flexible disk, a magneto-optical disk, a ROM, a writable nonvolatile memory such as a flash memory, a portable medium such as a CD-ROM, a hard disk built in a computer system, etc. This is a storage device.

  Further, the “computer-readable recording medium” refers to a volatile memory (for example, DRAM (Dynamic) in a computer system serving as a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. Random Access Memory)) that holds a program for a certain period of time is also included. The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design etc. of the range which does not deviate from the summary of this invention are included.

1-1, ..., 1-N, 1b-1, ... 1b-N, 1c-1, ..., 1c-N, 1e-1, ..., 1e-N Terminal equipment 2, 2c, 2d, 2e Base station Device 10, 10b, 10c, 10d, 10e Wireless communication system 100, 100-1, 100-2
101, 101-1, 101-2 Modulators 102, 102-1, 102-2 S / P (Serial / Parallel) converters 103, 103-1, 103-2 DFT units 104, 104-1, 104-2 Subcarrier mapping unit (signal placement unit)
105, 105c, 105-1, 105-2 Signal removal unit 106, 106-1, 106-2 IFFT unit 107, 107-1, 107-2 P / S (parallel / serial) conversion unit 108, 108-1, 108-2 CP (Cyclic Prefix) insertion units 109, 109-1, 109-2 D / A conversion units 110, 110-1, 110-2 Radio unit 111 Transmission antenna unit 112 Reception antenna unit 113 Radio unit 114 A / D Conversion unit 115 Reception unit 116 Transmission device 120, 120b, 120c RB selection unit (set selection unit, acquisition unit)
120e RB control unit (resource block control unit)
130, 130c, 130e Transmission signal generators 140, 140b, 140c, 140e Transmission unit 200 Reception 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 209 Cancellation unit 210 Equalization unit 211 Demodulation / error correction decoding unit 213 Determination unit 214 Channel estimation unit 216 Channel multiplication unit 217 DFT unit 218 Replica generation unit 219 Scheduling unit 220 Transmission unit 221 D / A conversion unit 222 Radio unit 223 Transmitting antenna 230 Receiving device 240 Control device

Claims (21)

A transmission device that transmits data to the base station based on a position on the frequency axis of a unit frequency band notified from the base station,
An acquisition unit that acquires mapping information indicating that a plurality of sets of the unit frequency bands whose positions are continuous on the frequency axis are assigned;
Based on the mapping information acquired by the acquisition unit, among the frequency bands indicated by the plurality of sets, the data is transmitted using a frequency band indicated by a use set used for transmission, and an unused set not used for transmission is present. A transmitter that does not transmit the data using the frequency band shown;
A transmission device comprising:   2. The transmission according to claim 1, wherein the transmission unit includes a set selection unit that selects the unused set from the set indicated by the mapping information acquired by the acquisition unit based on the mapping information. apparatus. The transmitter is
A signal arrangement unit that arranges a signal in a frequency band indicated by the mapping information acquired by the acquisition unit;
A signal removing unit that removes a signal arranged in a frequency band indicated by an unused set selected by the set selection unit from among signals after the signal arranging unit arranges the signal;
With
The transmission apparatus according to claim 2, wherein the data is transmitted using the signal removed by the signal removal unit.   The set selection unit calculates a clipping rate based on a total of frequency bands included in each of the sets and a frequency band included in each of the sets, and uses it for transmission based on the calculated clipping rate. The transmission apparatus according to claim 3, wherein a use frequency band is selected.   The set selection unit, when the calculated clipping rate is smaller than a predetermined threshold, determines to delete the frequency band of a part of the set, the frequency band other than the frequency band determined to be deleted The transmission apparatus according to claim 4, wherein the transmission apparatus is selected as a use frequency band.   The threshold is set based on any one or a combination of two or more of a modulation scheme, a coding rate, a transmission rate, a system bandwidth, a distance on the frequency axis between sets, or a system band. The transmitting apparatus according to claim 5, wherein:   The set selection unit calculates, for each set, an occupancy ratio that is a ratio of frequency bands included in the set to a total of frequency bands included in each of the sets, and based on the calculated occupancy ratio for each set, the clipping The transmission device according to any one of claims 4 to 6, wherein a rate is calculated.   The set selection unit acquires transmission power designated from a base station device, and uses the frequency band of the set, the acquired transmission power, and a predetermined maximum transmission power reduction amount, based on the used frequency. The transmission apparatus according to claim 4, wherein a band is selected.   The set selection unit calculates a clipping rate based on a total frequency band obtained by summing up the frequency bands of each set and the frequency band of each set, and the calculated clipping rate and the acquired transmission power are calculated in advance. 9. The transmission apparatus according to claim 8, wherein the use frequency band is selected based on a determined reduction amount of the maximum transmission power.   The transmission device according to any one of claims 3 to 9, wherein the signal to be placed by the signal placement unit is a signal obtained by performing time-frequency conversion on the data. .   When the transmission unit includes a frequency band that is prohibited from being used in a plurality of subcarriers designated by the base station, the transmission unit is configured to use a frequency band other than the frequency band that is prohibited from being used. The transmission apparatus according to claim 1, wherein a transmission signal in which a signal is arranged is transmitted. The transmitter is
When the base station apparatus notifies that transmission signals are transmitted in a plurality of system bands and the total transmission power required for transmission exceeds a predetermined value, all signals in at least one system band are clipped. A resource block control unit;
A transmission signal generation unit that generates a transmission signal in which signals are arranged for subcarriers in the system band that the resource block control unit does not target for clipping;
The transmission apparatus according to claim 1, further comprising:   The transmission device according to claim 12, wherein the transmission unit transmits data to be transmitted in a system band which is a target of clipping by the resource block control unit, in another system band.   The transmission signal generation unit performs clipping so that subcarriers used in other system bands are the number of subcarriers designated by the base station. Transmitter device.   The transmission device according to any one of claims 12 to 14, wherein the predetermined value is determined based on MPR. The transmitter is
A resource block controller that is notified from the base station device that transmission signals are transmitted in a plurality of system bands, and that clips all signals in at least one system band according to the positional relationship of the system bands used for transmission;
A transmission signal generation unit that generates a transmission signal in which signals are arranged for subcarriers in the system band that the resource block control unit does not target for clipping;
The transmission apparatus according to claim 1, further comprising:   The transmission apparatus according to claim 16, wherein the positional relationship of the system bands used for the transmission is whether or not the system bands to be used are continuous in a frequency domain.  The transmission according to any one of claims 12 to 17, wherein the signal to be arranged by the transmission signal generation unit is a signal obtained by performing time-frequency conversion on the data. apparatus.   Obtaining mapping information indicating that a plurality of sets of unit frequency bands in which positions on the frequency axis of unit frequency bands are continuous on the frequency axis are assigned, and based on the acquired mapping information, A processor comprising: a set selection unit that selects a part of a set as a non-use set that is not used for transmission in a frequency band indicated by the set. A transmission method executed by a transmission device that transmits data to the base station based on the position on the frequency axis of the unit frequency band notified from the base station,
An acquisition procedure for acquiring mapping information indicating that a plurality of sets of the unit frequency bands in which the positions are continuous on the frequency axis are assigned;
Based on the mapping information acquired by the acquisition procedure, among the frequency bands indicated by the plurality of sets, the data is transmitted using a frequency band indicated by a use set used for transmission, and an unused set not used for transmission is present. A transmission procedure that does not transmit the data using the indicated frequency band;
A transmission method characterized by comprising: Based on the position on the frequency axis of the unit frequency band notified from the base station, to the computer of the transmission device that transmits data to the base station,
An acquisition step of acquiring mapping information indicating that a plurality of sets of the unit frequency bands in which the positions are continuous on the frequency axis are assigned;
Based on the mapping information acquired by the acquisition step, the data is transmitted using the frequency band indicated by the use set used for transmission among the frequency bands indicated by the plurality of sets, and there is an unused set not used for transmission. A transmission step of not transmitting the data using the indicated frequency band;
A sending program to execute.

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