JP2010245641A - Radio system, base station device, mobile station device, communication method, program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for improving reception quality by the effect of frequency selection diversity. <P>SOLUTION: A base station device estimates propagation path information based on a reference signal informed from a mobile station device, and determines the number of resource block groups and an assignment method according to the propagation path information, wherein a resource block group is a frequency bandwidth assigned to the mobile station device. When the number of resource block groups assigned to the mobile station device is a threshold r or below, a continuous frequency band is assigned, and precoding vector is determined for each resource block group. Specifically, the base station device determines precoding vectors PV (1) and PV (2) to be multiplied by RBG (2) and RBG (3), respectively. When the number of resource block groups assigned to the mobile station device is the threshold r or above, a frequency of high propagation path gain is selected, and a resource block group is assigned discretely without applying precoding to all of the resource block groups. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a communication technique, and in particular, a radio system, a base station apparatus, a mobile station apparatus, and a communication in which frequency band allocation information and a transmission apparatus efficiently notify transmission weight control information in transmission using a plurality of antennas. The present invention relates to a method and a program for causing a computer to execute the method.

  Standardization of the LTE (Long Term Evolution) system, which is the wireless communication system of the 3.9th generation mobile phone, is almost finished, and recently, LTE-A (4th generation wireless communication system, which is a further development of the LTE system). Standardization of LTE-Advanced, IMT-A, etc.) has started.

  The uplink (communication from the mobile station to the base station) of the LTE system employs DFT-S-OFDM (Discrete Fourier Transform Frequency Division Division Multiplexing, also referred to as SC-FDMA). In contrast, the LTE-A system places importance on backward compatibility of the LTE system and supports Clustered DFT-S-OFDM (Dynamic Spectrum Control (DSC), which can be expected to improve cell throughput in addition to supporting DFT-S-OFDM. : Dynamic Spectrum Control), also called DFT-S-OFDM with SDC (Spectrum Division Control).

  Clustered DFT-S-OFDM can select a frequency with a high propagation path gain from an available frequency band and discretely arrange the spectrum, thereby obtaining a high frequency selection diversity effect and improving cell throughput. It is a method.

  By the way, in the downlink (communication from the base station to the mobile station) of the LTE system, MIMO (Multiple-Input Multiple-Output) multiplex transmission using a plurality of transmission antennas and transmission diversity are adopted. When transmitting data from multiple antennas such as MIMO and transmission diversity at the same time and the same frequency, precoding (Precoding (Precoding) is a technique to suppress the degradation of reception quality due to the reverse phase of spatially multiplexed signals. ) Is employed (see Non-Patent Document 1 below). Precoding multiplies a precoding vector (also called transmission weight) that gives a phase rotation according to the propagation path of each antenna, so that signals transmitted from multiple antennas can be properly received on the receiving side. It is synthesized and reception quality can be improved.

  The precoding vector to be multiplied on the transmission side is determined by the reception device based on a reference signal transmitted from the transmission device to the reception device, and is referred to as a precoding matrix indicator (hereinafter referred to as PMI) as control information to the transmission device. .) Is fed back. In addition, in the application of the precoding vector, since the influence of fading differs for each frequency, it is preferable to multiply the optimum precoding vector for each frequency. In LTE, the minimum unit of frequency that can be allocated is a resource block, and a different precoding vector is multiplied for each resource block group composed of one or more resource blocks to improve reception quality.

  When the number of resource block groups used by a transmission apparatus increases, the PMI data size increases, but it has been proposed that the PMI size is not increased by switching the presence or absence of PMI feedback depending on the size of transmission data (described below). Patent Document 1).

  Even in the uplink of the LTE-A system, it is determined that a mobile station as a transmission apparatus has a plurality of transmission antennas, and a method for improving frequency utilization efficiency and coverage by using MIMO and transmission diversity is proposed. At the same time, application of precoding has also been proposed (see Non-Patent Document 2). Therefore, also in the uplink, it is necessary to notify the mobile station of PMI that is information indicating a precoding vector from the base station that is a receiving apparatus, and to apply precoding.

JP 2008-236428 A

3GPP TS 36.211 (V8.5.0) “Evolved Universal Terrestrial Radio Access (E-UTRA) Physical Channels and Modulation” Nokia Siemens Networks, Nokia, R1-090727, “UL Single User MIMO Schemes in LTE-Advanced”

  However, when PMI is notified in resource block group units, the control information increases, resulting in a decrease in throughput. In addition, when the data size increases, there is a problem that unless the PMI is notified to reduce control information, an optimal precoding vector cannot be selected and reception quality deteriorates.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique for improving reception quality by a frequency selection diversity effect.

  The present invention applies precoding when the amount of control information related to precoding is small, and reduces the amount of precoding control information when the amount of precoding information is large, and switches the frequency band allocation method to change the propagation characteristics. To improve. According to the present invention, when the PMI data size to be notified is small, the reception characteristics are improved by precoding, and when the PMI notification information is large, a frequency with a high channel gain is used without using a precoding vector. By using it, the reception quality can be improved due to the effect of frequency selection diversity.

  According to an aspect of the present invention, a base station device that is a receiving device is connected to the transmitting device in a frequency band that includes a base station device and a mobile station device, and is used for data transmission by the mobile station device that is a transmitting device. A wireless communication system for notifying allocation information of a general frequency band or a discrete frequency band, wherein precoding is performed by switching a precoding application method in the base station apparatus according to frequency band allocation information to the mobile station apparatus A wireless communication system having a determination unit is provided. For this reason, the base station apparatus only needs to notify the mobile station apparatus of only information in which frequency bands are discretely allocated, and PMI notification is unnecessary. It is possible to compensate for characteristic deterioration due to the absence of precoding by the frequency selective diversity effect.

  When transmitting the same transmission bit from a plurality of antennas of the mobile station apparatus, the precoding determination unit determines a frequency band in the base station apparatus based on a frequency bandwidth that the mobile station apparatus uses for data transmission. It is preferable to change the allocation method and switch the precoding application method.

  In addition, in a frequency band that includes a base station device and a mobile station device and is used for data transmission by the mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency band to the transmission device. If the frequency band used by the mobile station device for data transmission is narrow, the base station device continuously sends the frequency band to the mobile station device. When the mobile station apparatus uses a wide frequency band for data transmission, the frequency band is allocated to the mobile station apparatus discretely and precoding is not applied. A wireless communication system is provided.

  For this reason, the base station apparatus only needs to notify the mobile station apparatus of only information in which frequency bands are discretely allocated, and PMI notification is not necessary. It is possible to compensate for characteristic deterioration due to the absence of precoding by the frequency selective diversity effect. In addition, in a frequency band that includes a base station device and a mobile station device and is used for data transmission by the mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency band to the transmission device. If the frequency band used by the mobile station device for data transmission is narrow, the base station device continuously sends the frequency band to the mobile station device. If the frequency band to be used for transmission is wide, the frequency band is discretely assigned to the mobile station device, and all the frequency bands used by the mobile station device are allocated. A wireless communication system characterized by applying a single precoding is provided.

  In addition, in a frequency band that includes a base station device and a mobile station device and is used for data transmission by the mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency band to the transmission device. In this case, the base station apparatus continuously transmits frequency bands to the mobile station apparatus when the mobile station apparatus uses a narrow frequency band for data transmission. If the frequency band used for transmission is wide, the frequency band is discretely assigned to the mobile station device, and is determined in advance in a constant frequency bandwidth unit. A wireless communication system characterized by applying precoding is provided.

  In addition, in a frequency band that includes a base station device and a mobile station device and is used for data transmission by the mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency band to the transmission device. A wireless communication system for notifying allocation information of a frequency band, wherein the base station device transmits the same transmission bit from a plurality of antennas of the mobile station device based on a propagation path of the mobile station device. The present invention provides a wireless communication system characterized by switching a precoding application method.

  The base station device continuously assigns a frequency band to the mobile station device when the channel of the mobile station device cannot obtain a constant reception quality even if the channel of the mobile station device assigns the frequency band discretely. When precoding is applied in units of frequency bandwidths and the transmission path of the transmission device is assigned discretely, when maintaining a constant reception quality, the frequency band is discretely assigned to the mobile station device and precoding is performed. It is preferable not to apply. The base station device determines the reception quality based on an average value of received SINRs in a minimum unit frequency band to which reception quality is discretely allocated, and a frequency bandwidth exceeding a threshold reception SINR when discretely allocated is determined by the mobile station device. It is preferable to determine the assignment continuously when it is narrower than the frequency bandwidth to be used. Note that “a certain frequency bandwidth unit” indicates a resource block group.

  The base station device continuously assigns a frequency band to the mobile station device when the channel of the mobile station device cannot obtain a constant reception quality even if the channel of the mobile station device assigns the frequency band discretely. In the case where precoding is applied in units of frequency bandwidths and the propagation path of the transmission device is discretely assigned, and when a constant reception quality is maintained, the frequency band is discretely assigned to the mobile station device, and the constant frequency It is preferable to apply precoding predetermined in bandwidth units.

  The present invention includes a base station device and a mobile station device, and in a frequency band used by a mobile station device that is a transmission device for data transmission, a base station device that is a reception device has a continuous frequency band or A radio communication system for notifying allocation information of discrete frequency bands, wherein the base station device transmits data when different transmission bits are transmitted from a plurality of antennas of the mobile station device. Based on the frequency bandwidth to be used, the method for assigning the frequency band to the mobile station apparatus is changed, and at the same time, the precoding application method is switched by any of the following methods 1) to 3) A wireless communication system. 1) When the frequency band used for data transmission by the mobile station device is narrow, the base station device continuously assigns a frequency band to the mobile station device, performs precoding in a certain frequency bandwidth unit, When the frequency band used for transmission is wide, the frequency band is discretely assigned to the mobile station apparatus, and precoding is not applied. 2) When the frequency band used for data transmission by the mobile station device is narrow, the base station device continuously assigns the frequency band to the mobile station device, and performs precoding in a certain frequency bandwidth unit, When the frequency band used for transmission is wide, a frequency band is discretely assigned to the mobile station apparatus, and a single precoding is applied to all the frequency bands used by the mobile station apparatus. 3) When the frequency band used by the mobile station device for data transmission is narrow, the base station device continuously assigns the frequency band to the mobile station device, and performs precoding in a certain frequency bandwidth unit, When the frequency band used for transmission is wide, the frequency band is allocated to the mobile station device discretely, and precoding predetermined in a certain frequency bandwidth unit is applied.

  In addition, in a frequency band that includes a base station device and a mobile station device and is used for data transmission by the mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency band to the transmission device. In the wireless communication system for notifying the allocation information of the frequency band, the base station device, when transmitting different transmission bits from a plurality of antennas of the mobile station device, based on the propagation path of the mobile station device, The wireless communication system may be characterized in that the application method of precoding is switched by any one of the following methods 1) to 3). 1) The base station apparatus continuously allocates frequency bands to the mobile station apparatus when a certain reception quality cannot be obtained even if the propagation path of the mobile station apparatus performs discrete frequency band allocation. When precoding is applied in units of a certain frequency bandwidth, and when the transmission path of the transmission apparatus is assigned discretely, a constant reception quality is maintained, the frequency band is discretely assigned to the mobile station apparatus, Do not apply coding. 2) The base station apparatus continuously allocates frequency bands to the mobile station apparatus when a certain reception quality cannot be obtained even though the propagation path of the mobile station apparatus performs discrete frequency band allocation. When precoding is applied in a unit of a certain frequency bandwidth, and when the transmission path of the transmission device is discretely assigned, when maintaining a constant reception quality, the frequency band is discretely assigned to the mobile station device and transmitted. A single precoding is applied to all frequency bands used by the device. 3) The base station apparatus continuously allocates frequency bands to the mobile station apparatus when a certain reception quality cannot be obtained even though the propagation path of the mobile station apparatus performs discrete frequency band allocation. When precoding is applied in units of a certain frequency bandwidth and when a transmission path of a transmission apparatus is discretely allocated, a constant reception quality is maintained. In this case, a frequency band is discretely allocated to the mobile station apparatus. Precoding determined in advance in units of frequency bandwidths is applied.

  According to another aspect of the present invention, a base station apparatus that is a receiving apparatus includes a base station apparatus and a mobile station apparatus, and a base station apparatus that is a receiving apparatus is connected to the transmitting apparatus in a frequency band that the mobile station apparatus that is a transmitting apparatus uses for data transmission. A base station apparatus in a radio communication system for notifying allocation information of continuous frequency bands or discrete frequency bands, and changing a frequency band allocation method allocated to the mobile station apparatus and switching a precoding application method Is provided.

  In addition, in a frequency band that includes a base station device and a mobile station device and is used for data transmission by the mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency band to the transmission device. Mobile station apparatus in a wireless communication system for notifying allocation information of a specific frequency band, and a method of applying precoding based on the allocated frequency band and the presence / absence of application of precoding or precoding pattern information There is provided a mobile station apparatus characterized in that data transmission is performed while changing the above.

  According to still another aspect of the present invention, a base station apparatus that is a receiving apparatus includes a base station apparatus and a mobile station apparatus, and the base station apparatus that is a receiving apparatus uses the transmitting apparatus in a frequency band that the mobile station apparatus that is the transmitting apparatus uses for data transmission. Is a communication method on the base station apparatus side in a wireless communication system that notifies allocation information of continuous frequency bands or discrete frequency bands, and when the frequency band used for data transmission by the mobile station apparatus is narrow, When the frequency band is continuously allocated to the mobile station apparatus, precoding is performed in a unit of a certain frequency bandwidth, and the mobile station apparatus uses a wide frequency band for data transmission, the frequency band is discretely A communication method is provided that is allocated to a mobile station apparatus and does not apply precoding. In addition, in a frequency band that includes a base station device and a mobile station device and is used for data transmission by the mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency band to the transmission device. A communication method on a mobile station apparatus side in a wireless communication system for notifying allocation information of a frequency band, and when a frequency band used for data transmission is narrow, a frequency band is continuously allocated from the base station apparatus Communication in which precoding is performed in units of a certain frequency bandwidth, and when the frequency band used for data transmission is wide, frequency bands are discretely allocated from the base station apparatus and precoding is not applied. A method is provided.

  The present invention may be a program for causing a computer to execute the communication method described above, or a computer-readable recording medium for recording the program. The program may be obtained by a transmission medium such as the Internet.

  By applying the present invention, it is possible to improve transmission characteristics while suppressing an excessive increase in control information related to precoding. Therefore, when the data size of the PMI increases, the reception quality can be improved without extremely increasing the data size of the control information.

It is a functional block diagram which shows the example of 1 structure of the mobile station which is a transmitter by one embodiment of this invention. It is a functional schematic block diagram which shows the example of 1 structure of the transmission data generation part of a transmitter. It is a functional block diagram which shows the example of 1 structure of the base station which is a receiver by one embodiment of this invention. It is an example of the resource block group allocated to the mobile station by this Embodiment, FIG. 4 a) is a case where there are few, and FIG. 4 b) is a figure which shows an example when there are many. It is a figure which shows an example which switches the application method of precoding by the propagation path gain by this Embodiment. It is a figure which shows the structural example of the base station which is a receiver in the case of using MIMO. It is a functional block diagram which shows one structural example of a signal separation part.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following embodiment, an example in which two antennas are used for the transmission device and the reception device has been described. However, the present invention can also be applied to a case where there are three or more antennas. Moreover, although the following embodiment demonstrated the example which applied this invention to the uplink, the application range is not restricted to an uplink. Although the transmission method of the mobile station which is a transmitting apparatus is described as a single carrier, it can also be applied to a multicarrier.

  FIG. 1 is a functional block diagram illustrating an example of a mobile station apparatus that is a transmission apparatus according to the present embodiment. The mobile station apparatus A includes a first transmission data generation unit 101, a first precoding unit 105, a first transmission processing unit 106, a first radio unit 107, and a second radio unit 110 as a configuration related to the antenna 108. , A reception processing unit 111, a control information acquisition unit 112, and a precoding information acquisition unit 113, and similarly for the antenna 127, the second transmission data generation unit 121, the second precoding unit 124, and the second transmission A processing unit 125 and a third wireless unit 126 are provided.

  In the mobile station device A, the control information notified from the base station device which is a receiving device is received by the first antenna 108, and the received signal is down-converted to the baseband frequency by the second radio unit 110 and received. The data is output to the processing unit 111. The signal input to the reception processing unit 111 is demodulated, and the control information acquisition unit 112 extracts control information from the signal. From the extracted control information, frequency allocation information is input to first transmission data generation section 101, and PMI, which is information on a precoding vector used for transmission, is output. In FIG. 1, the control information is acquired using only the reception signal of the first antenna, but may be acquired using the second antenna. Precoding information acquisition section 113 inputs PMIs indicating precoding vectors used for transmission by first antenna 108 and second antenna 127 to first precoding section 105 and second precoding section 124, respectively. .

  On the other hand, the transmission bits are converted into transmission data by the first transmission data generation unit 101, and the first precoding unit 105 performs precoding based on the PMI notified from the base station apparatus. Further, the precoded transmission data is subjected to transmission processing by the first transmission processing unit 106, up-converted to a radio frequency by the first radio unit 107, and transmitted from the first antenna 108. Since transmission from the second antenna 127 is the same as that of the first antenna 108, the description thereof is omitted.

  FIG. 2A is a functional block diagram illustrating a configuration example of the first transmission data generation unit 101. The first transmission data generation unit 101 includes an encoding unit 1001, a modulation unit 1002, a DFT unit 1003, a transmission data arrangement unit 1004, a reference signal generation unit 1005, and a reference signal multiplexing unit 1006.

  The transmission bits input to the first transmission data generation unit 101 are subjected to error correction coding in the coding unit 1001 and converted into code bits. The modulation unit 1002 modulates the code bits into modulation symbols such as QPSK (Quadrature Phase Shift Keying) and 16QAM (16 Quadrature Amplitude Modulation). The modulation symbol is converted into a frequency domain signal by the DFT unit 1003, a frequency signal is arranged based on the frequency allocation information notified from the base station apparatus by the transmission data arrangement unit 1004, and is generated by the reference signal generation unit 1005. The reference signal multiplexing unit 1006 multiplexes the received signals.

  The configuration of the transmission processing unit in FIG. 1 is shown in FIG. The first transmission processing unit 106 includes an IDFT unit 1011 and a CP insertion unit 1012. In the transmission processing unit 106, the frequency signal subjected to precoding is input to an IDFT (Inverse DFT; Inverse Discrete Fourier Transform) unit 1011 and converted into a time signal. A cyclic prefix is added to the time signal in a CP (Cyclic Prefix) insertion unit 1012.

  FIG. 3 is a schematic block diagram illustrating a configuration example of the base station apparatus B which is a receiving apparatus. The base station apparatus B includes a first radio unit 202, a first CP removal unit 203, a first DFT unit 204, a first reference signal separation unit 205, and a first transmission as a configuration related to the first antenna 201. Data extraction section 206, first propagation path compensation section 207, IDFT section 208, demodulation section 209, propagation path estimation section 210, band allocation determination section 211, precoding determination section 212, control information generation section 213, transmission processing section 214 , A first buffer 215, a signal synthesizer 216, and a decoder 218. Similarly, the second antenna 221 includes a second radio unit 222, a second CP removal unit 223, and a second DFT unit. 224, a second reference signal separation unit 225, a second transmission data extraction unit 226, a second propagation path compensation unit 227, and a second buffer 217.

  The first radio unit 202 receives the signal transmitted from the mobile station apparatus A by the first antenna 201, and down-converts this signal to the baseband frequency. The received signal input from the first radio section 202 is subjected to cyclic prefix removal by the first CP removal section 203 and converted to a frequency signal by the first DFT section 204. The first reference signal separation unit 205 separates the reference signal from the frequency signal, and the reference signal is input to the first propagation path estimation unit 210. On the other hand, the frequency signal from which the reference signal is separated is input to the first transmission data extraction unit 206. Since the reference signal input to the first propagation path estimation unit 210 is a known signal in the mobile station and base station apparatus B used for propagation path measurement, the received reference signal is compared with the known signal, It is possible to know the propagation path information. In the propagation path estimation unit 210, the estimated propagation path information is input to the band allocation determination unit 211, the first propagation path compensation unit 207, and the second propagation path compensation unit 227. Band allocation determining section 211 determines the frequency band of the frequency allocated to the mobile station by band allocation determining section 211 based on the propagation path information, and inputs the frequency band allocation information and the propagation path information to precoding determining section 212. Further, the frequency band allocation information is also input to the first buffer 215 and the second buffer 217. The determination of the frequency band assignment is made according to the number of resource blocks, which is the bandwidth of the frequency to be assigned to the mobile station, and the magnitude of channel fluctuation. The precoding determination unit 212 receives the frequency band allocation information and the propagation path information determined by the band allocation determination unit 211 from the band allocation determination unit 211 and uses the precoding used by the mobile station apparatus based on the input information. And a mobile station apparatus determines a precoding vector to be multiplied with transmission data, and inputs frequency band allocation information and PMI to control information generation section 213. Control information generation section 213 generates control information from frequency band allocation information and PMI, and the transmission processing section performs control information transmission processing.

  On the other hand, the reception data from which the reference signal is separated is input to the first transmission data extraction unit 206, and the transmission data is extracted based on the frequency band allocation information stored in the first buffer 215. The extracted transmission data is transmitted from the first propagation path compensation unit 207 to a wireless propagation path such as a minimum mean square error (MMSE) weight using the frequency response estimated by the propagation path estimation unit 210. Multiply the weight to compensate for the distortion. The received signal of the first antenna 201 subjected to propagation path compensation and the second antenna 221 subjected to the same processing as the first antenna 201 is synthesized by the signal synthesis unit 216 and the time signal is obtained by the IDFT unit 208. And demodulated by the demodulator 209 from received modulation symbols to received code bits. Decoding processing is performed by the decoding unit 218 from the code bit, and a transmission bit is obtained.

[First Embodiment]
In the first embodiment of the present invention, when transmission diversity in which the transmission bits transmitted from the antenna 108 and the antenna 127 in FIG. 1 are the same is used, precoding is performed based on the bandwidth of the frequency allocated to the mobile station apparatus. A method of switching the application method will be described. An example of this embodiment will be described with reference to FIG. FIG. 4a is a case where there are few resource block groups allocated to the mobile station apparatus, and FIG. 4b is a diagram illustrating an example where there are many resource block groups allocated to the mobile station apparatus. In this embodiment, the minimum unit to which the precoding vector is applied is a resource block group, but the minimum unit to which precoding is applied may not be a resource block group.

  The base station apparatus B estimates propagation path information based on the reference signal notified from the mobile station apparatus A, and determines the number of resource block groups that are frequency bandwidths allocated to the mobile station apparatus A from the propagation path information and the like. . r is a threshold value for determining whether the mobile station apparatus has a small number of allocated resource block groups. When the number of resource block groups to be allocated to the mobile station apparatus is less than or equal to r, the mobile station apparatus has a small number of allocated resource block groups, allocates continuous frequency bands, and determines a precoding vector for each resource block group. . Specifically, as shown in FIG. 4a, when the number of resource block groups to be allocated to the mobile station apparatus is small, precoding vectors PV (1) and PV (1) that multiply RBG (2) and RBG (3), respectively. 2) is determined by the base station apparatus.

  The mobile station apparatus is notified of the PMI and frequency band allocation information indicating PV (1) and PV (2) determined in this procedure as control information. When the number of resource block groups to be allocated to the mobile station apparatus is larger than r, the mobile station apparatus has a large number of allocated resource block groups, and precoding is not applied to all resource block groups, and the channel gain is high. Select a frequency and assign resource block groups discretely.

  Specifically, PV = 1, that is, no precoding vector is applied to all of the allocated resource block groups, RBG (1), RBG (3), RBG (4),... (Indicated by arrows) in FIG. . When the number of resource block groups is large, the data size related to PMI becomes large, so that frequency bands are discretely allocated so that a high frequency selection diversity effect can be obtained without applying precoding. For this reason, the base station apparatus only needs to notify the mobile station apparatus of only information in which frequency bands are discretely allocated, and PMI notification is unnecessary. In this embodiment, when frequency bands are discretely allocated, precoding is not applied, but the same precoding is applied to all frequency bands used by the mobile station apparatus. Also good. Alternatively, the precoding vector to be applied may be changed for each resource block group in a pattern determined in advance between the base station apparatus and the mobile station apparatus. Also, r used to determine whether or not the PMI information increases is determined based on the bit size of the control information.

For example, when PMI is represented by P _TX bits, the number of _RBs that can be allocated to mobile station apparatuses in the system band is N _RB , the number of resource blocks that constitute a resource block group is P, and discrete The frequency band allocation information amount when the frequency band is allocated in the following manner is expressed by the following equation.

は、Xを超えない最大の整数とする。 Bit However,

Is the largest integer not exceeding X.

  The frequency band allocation information amount when frequency bands are continuously allocated is expressed by the following equation.

Bit r is determined by the following equation.

  In the above equation, only the number of control information bits is considered, but considering the characteristic difference between the case where single precoding is performed in all bands and the case where precoding is performed for each resource block group, Changes in the formula are also included in the present invention.

  By applying this embodiment, when the number of resource block groups allocated to the mobile station apparatus is small, it is possible to improve reception characteristics by precoding. In addition, when the number of resource block groups allocated to the mobile station apparatus is large, it is possible to improve reception characteristics by the frequency selection diversity effect while suppressing an increase in the information amount of PMI.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a diagram illustrating an example of switching the precoding application method according to the channel gain according to the present embodiment.

  An example of switching the precoding application method according to the channel gain will be described below in the present embodiment. In this embodiment, transmission diversity in which transmission bits transmitted from the first antenna 108 and the second antenna 127 shown in FIG. 1 are the same is used. RBG (1) to RBG (8) in FIGS. 5a) and 5b) are resource block groups that can be allocated to the mobile station apparatus, and L1 and L2 are threshold values that determine whether or not to apply precoding based on the channel gain. To do. The propagation path gain is calculated based on a received SINR (Signal to Interference and Noise Ratio). The propagation path gain of the resource block group may be the average of the propagation path gains of the subcarriers in the resource block group, or may be any value such as a maximum value or a minimum value.

  In this embodiment, when the number of resource block groups in which the channel gain exceeds a certain value among the assignable resource block groups exceeds the number of resource block groups assigned by the mobile station, the frequency band is discretely allocated. When the allocation is performed and the number of resource block groups allocated to the mobile station is lower, frequency bands are allocated continuously and precoding is applied in units of resource block groups.

  In FIGS. 5 a) and b), for the sake of simplicity, it is assumed that the number of assignable resource block groups is 8, and the number of resource block groups assigned to the mobile station apparatus is 4.

  FIG. 5a) is a diagram illustrating an example of the case where the number of resource blocks whose channel gain exceeds L1, which is the threshold, out of allocatable resource block groups exceeds the number of resource block groups allocated to the mobile station apparatus. . In this case, high frequency selection diversity is achieved by discretely allocating frequency bands to RBG (1), RBG (4), RBG (5), and RBG (8), which are resource block groups having a high channel gain. An effect is obtained.

  On the other hand, FIG. 5b) shows a case where the number of resource blocks in which the channel gain exceeds the threshold value L2 out of the assignable resource block groups is less than the number of resource block groups assigned to the mobile station apparatus. In this case, even if a resource block group having a high channel gain is selected, a sufficient frequency selection diversity effect cannot be obtained. Therefore, resource block groups are continuously allocated, and a precoding vector is applied to each resource block group. Thus, control is performed so as to maintain a constant reception quality.

  When a sufficient frequency selection diversity effect is obtained by applying this embodiment, resource block groups are used discretely, and when the frequency selection diversity effect is not sufficient, the reception quality is improved by precoding. Can do.

  In this embodiment, the channel gain reference is the reception SINR, but other criteria such as a reception SNR (Signal Noise Ratio) may be used. Moreover, although the propagation path gain of the resource block group is an average of the resource blocks, other criteria such as the maximum value or the minimum value of the resource block may be used. In addition, when frequency bands are discretely assigned, precoding is not applied, but the same precoding may be applied to all frequency bands used by the mobile station. Alternatively, the precoding vector to be applied may be changed for each precoding group in a pattern determined in advance between the base station and the mobile station.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. In the present embodiment, when MIMO using different transmission bits transmitted from first antenna 108 and second antenna 127 is used, the precoding is performed depending on the bandwidth of the frequency allocated to the mobile station apparatus and the channel gain. Switch the application method.

  The configuration of the mobile station apparatus, which is a transmission apparatus when using MIMO, is the same as that in FIG. 1, and the transmission bits transmitted from the first antenna 108 and the second antenna 127 are different. Therefore, the transmission bits input to the first transmission data generation unit 101 and the second transmission data generation unit 121 are different.

  FIG. 6 is a diagram illustrating a configuration example of a base station apparatus which is a receiving apparatus when MIMO is used. The base station apparatus C includes a first radio unit 602, a first CP removal unit 603, a first DFT unit 604, a first reference signal separation unit 605, and a signal separation unit 606 as a configuration related to the first antenna 601. , A first demodulation unit 608, a propagation path estimation unit 610, a band allocation determination unit 611, a precoding determination unit 612, a control information generation unit 613, a transmission processing unit 614, and the second antenna 621 similarly. 2 radio units 622, a second CP removing unit 623, a second DFT unit 624, a second reference signal separating unit 625, and a second demodulating unit 626.

  As for the signal received by the first antenna 601, the reception data processed from the first radio unit 601 to the first reference signal separation unit 605 is sent to the signal separation unit 606 in the same manner as the reception processing described in FIG. Entered. The same processing is performed on the received signal of the second antenna 621 and the signal is input to the signal separation unit 606. The propagation path estimation unit 610 estimates propagation path information based on the reference signal separated from the received signal by the first reference signal separation unit 605 and the second reference signal separation unit 625, and the first antenna 601. And the information on the propagation path between the second antenna 621 and the second antenna 621 are input to the signal separation unit 606. Also, the band allocation determination unit 611 determines a frequency band to be allocated to the mobile station apparatus based on the propagation path information input by the propagation path estimation unit 610 and inputs the frequency band allocation information to the signal separation unit 606. The received signal from which the reference signal is separated is subjected to signal separation in the signal separation unit 606 based on propagation path information and frequency band allocation information, and the first demodulation unit 608 and the second demodulation unit 626 Each is converted into a received code bit.

  FIG. 7 is a functional block diagram illustrating a configuration example of the signal separation unit 606. The signal separation unit 606 includes a multiplication weight generation unit 701, a MIMO separation unit 702, a first buffer 703, a first transmission data extraction unit 704, a first IDFT unit 706, a second buffer 707, and second transmission data. An extraction unit 708 and a second IDFT unit 709 are provided.

  In the signal separation unit 606, information on propagation paths of the first antenna 601 and the second antenna 621 is input to the multiplication weight generation unit 701. Multiplication weight generation section 701 calculates a weight for multiplying the received signal based on the input propagation path information, and inputs it to MIMO separation section 702. The weights multiplied by the received signal are MMSE weights, ZF (Zero Forcing) weights, and the like. The MIMO separation unit 702 receives a weight to be multiplied with the reception signals of the first antenna 601 and the second antenna 621 from which the reference signal is separated, separates the spatially multiplexed signals, and performs first transmission data The data is input to the extraction unit 704 and the second transmission data extraction unit 708. On the other hand, the first buffer 703 holds the frequency band allocation information input from the band allocation determination unit 611, and inputs the frequency band allocation information to the first transmission data extraction unit 704.

  The first transmission data extraction unit 704 extracts frequency band information to which transmission data is allocated based on the frequency band allocation information input from the first buffer 703 from the separated signal. The extracted transmission data is converted into a time signal by the first IDFT 706. The signal received by the second antenna 621 is similarly processed and converted into a time signal by the second IDFT 709.

  Even in the case of using MIMO, as in the first embodiment, based on the bandwidth of the frequency allocated to the mobile station apparatus, by changing the presence / absence of precoding application and the minimum unit to which precoding is applied, The same effects as those of the embodiment can be obtained. Further, the same effect as in the second embodiment can be obtained by switching the precoding application method according to the propagation channel gain in the case of using MIMO.

  As described above, according to the present embodiment, it is possible to improve transmission characteristics while suppressing an increase in control information related to precoding from being extremely increased. Therefore, when the data size of the PMI increases, the reception quality can be improved without extremely increasing the data size of the control information.

  It should be noted that a program for realizing the above functions may be recorded on a computer-readable recording medium, the program recorded on the recording medium may be read into a computer system, and the processing of each unit may be performed. . The “computer system” here includes an OS and hardware such as peripheral devices.

  The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time, like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case is also used to hold a program for a certain period of time. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the embodiment, and the invention is a design change and the like within the scope not departing from the gist of the present invention. Is also included.

  The present invention is applicable to a communication device.

A ... mobile station apparatus, 101 ... first transmission data generation unit, 105 ... first precoding unit, 106 ... second transmission processing unit, 107 ... first radio unit, 108 ... first antenna, 110 ... second radio unit, 111 ... reception processing unit, 112 ... control information acquisition unit, 113 ... precoding information acquisition unit, 121 ... second transmission data generation unit, 124 ... second precoding unit, 125 ... first 2 transmission processing units, 126 ... third radio unit, 127 ... second antenna, B ... base station apparatus, 201 ... first antenna, 202 ... first radio unit, 203 ... first CP removal unit 204, first DFT unit, 205, first reference signal separating unit, 206, first transmission data extracting unit, 207, first propagation path compensating unit, 208, IDFT unit, 209, demodulating unit, 210. ... propagation path estimation unit, 211 ... band This determination unit, 212 ... precoding determination unit, 213 ... control information generation unit, 214 ... transmission processing unit, 215 ... first buffer, 216 ... signal synthesis unit, 217 ... second buffer, 221 ... second antenna 222, second wireless unit, 223, second CP removing unit, 224, second DFT unit, 225, second reference signal separating unit, 226, second transmission data extracting unit, 227, second. Propagation path compensation unit.

Claims (17)

In a frequency band that includes a base station device and a mobile station device and is used for data transmission by a mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency to the transmission device. A wireless communication system for notifying bandwidth allocation information,
A radio communication system, comprising: a precoding determining unit that switches a precoding application method in the base station apparatus according to frequency band allocation information to the mobile station apparatus. When transmitting the same transmission bit from a plurality of antennas of the mobile station device, the precoding determination unit,
The radio communication system according to claim 1, wherein the mobile station apparatus changes a frequency band allocation method in the base station apparatus and switches a precoding application method based on a frequency bandwidth used for data transmission. . In a frequency band that includes a base station device and a mobile station device and is used for data transmission by a mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency to the transmission device. A wireless communication system for notifying bandwidth allocation information,
When the frequency band used for data transmission by the mobile station device is narrow, the base station device continuously assigns a frequency band to the mobile station device, and performs precoding in a certain frequency bandwidth unit, The radio communication system according to claim 2, wherein when a frequency band used for data transmission by the mobile station apparatus is wide, frequency bands are discretely allocated to the mobile station apparatus and precoding is not applied. In a frequency band that includes a base station device and a mobile station device and is used for data transmission by a mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency to the transmission device. A wireless communication system for notifying bandwidth allocation information,
When the frequency band used for data transmission by the mobile station apparatus is narrow, the base station apparatus continuously assigns the frequency band to the mobile station apparatus, performs precoding in a certain frequency bandwidth unit, and transmits 3. When a frequency band used for the mobile station apparatus is wide, discrete frequency bands are allocated to the mobile station apparatus, and a single precoding is applied to all the frequency bands used by the mobile station apparatus. The wireless communication system according to 1. In a frequency band that includes a base station device and a mobile station device and is used for data transmission by a mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency to the transmission device. A wireless communication system for notifying bandwidth allocation information,
When the frequency band used by the mobile station device for data transmission is narrow, the base station device continuously assigns the frequency band to the mobile station device, performs precoding in a certain frequency bandwidth unit, and transmits 3. The method according to claim 2, wherein when a frequency band to be used is wide, frequency bands are discretely allocated to the mobile station apparatus, and precoding predetermined in a certain frequency bandwidth unit is applied. Wireless communication system. In a frequency band that includes a base station device and a mobile station device and is used for data transmission by a mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency to the transmission device. A wireless communication system for notifying bandwidth allocation information,
The base station apparatus switches a precoding application method based on a propagation path of the mobile station apparatus when transmitting the same transmission bit from a plurality of antennas of the mobile station apparatus .   The base station device continuously assigns a frequency band to the mobile station device when the channel of the mobile station device cannot obtain a constant reception quality even if the channel of the mobile station device assigns the frequency band discretely. When precoding is applied in units of frequency bandwidths and the transmission path of the transmission device is assigned discretely, when maintaining a constant reception quality, the frequency band is discretely assigned to the mobile station device and precoding is performed. The wireless communication system according to claim 6, wherein the wireless communication system is not applied.   The base station device determines the reception quality based on an average value of received SINRs in a minimum unit frequency band to which reception quality is discretely allocated, and a frequency bandwidth exceeding a threshold reception SINR when discretely allocated is determined by the mobile station device. 7. The wireless communication system according to claim 6, wherein the allocation is continuously determined when the frequency bandwidth is narrower than the frequency bandwidth to be used.   The base station device continuously assigns a frequency band to the mobile station device when the channel of the mobile station device cannot obtain a constant reception quality even if the channel of the mobile station device assigns the frequency band discretely. When precoding is applied in units of frequency bandwidths, and when the transmission path of the transmission device is discretely allocated, and maintaining a constant reception quality, the frequency band is discretely allocated to the mobile station device, and the transmission device The wireless communication system according to claim 6, wherein a single precoding is applied to all frequency bands to be used.   The base station device continuously assigns a frequency band to the mobile station device when the channel of the mobile station device cannot obtain a constant reception quality even if the channel of the mobile station device assigns the frequency band discretely. In the case where precoding is applied in units of frequency bandwidths and the propagation path of the transmission device is discretely assigned, and when a constant reception quality is maintained, the frequency band is discretely assigned to the mobile station device, and the constant frequency The wireless communication system according to claim 6, wherein precoding predetermined in units of bandwidth is applied. In a frequency band that includes a base station device and a mobile station device and is used for data transmission by a mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency to the transmission device. A wireless communication system for notifying bandwidth allocation information,
When the base station device transmits different transmission bits from a plurality of antennas of the mobile station device, the base station device allocates a frequency band to the mobile station device based on a frequency bandwidth used by the mobile station device for data transmission. A radio communication system characterized in that, at the same time as changing the method, the application method of precoding is switched by any one of the following methods 1) to 3).
1) When the frequency band used for data transmission by the mobile station device is narrow, the base station device continuously assigns a frequency band to the mobile station device, performs precoding in a certain frequency bandwidth unit, When the frequency band used for transmission is wide, the frequency band is discretely assigned to the mobile station apparatus, and precoding is not applied.
2) When the frequency band used for data transmission by the mobile station device is narrow, the base station device continuously assigns the frequency band to the mobile station device, and performs precoding in a certain frequency bandwidth unit, When the frequency band used for transmission is wide, a frequency band is discretely assigned to the mobile station apparatus, and a single precoding is applied to all the frequency bands used by the mobile station apparatus.
3) When the frequency band used by the mobile station device for data transmission is narrow, the base station device continuously assigns the frequency band to the mobile station device, and performs precoding in a certain frequency bandwidth unit, When the frequency band used for transmission is wide, the frequency band is allocated to the mobile station device discretely, and precoding predetermined in a certain frequency bandwidth unit is applied. In a frequency band that includes a base station device and a mobile station device and is used for data transmission by a mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency to the transmission device. A wireless communication system for notifying bandwidth allocation information,
When the base station apparatus transmits different transmission bits from a plurality of antennas of the mobile station apparatus, any one of the following 1) to 3) is applied as a precoding application method based on the propagation path of the mobile station apparatus. A wireless communication system characterized by switching by any of the above methods.
1) The base station apparatus continuously allocates frequency bands to the mobile station apparatus when a certain reception quality cannot be obtained even if the propagation path of the mobile station apparatus performs discrete frequency band allocation. When precoding is applied in units of a certain frequency bandwidth, and when the transmission path of the transmission apparatus is assigned discretely, a constant reception quality is maintained, the frequency band is discretely assigned to the mobile station apparatus, Do not apply coding.
2) The base station apparatus continuously allocates frequency bands to the mobile station apparatus when a certain reception quality cannot be obtained even though the propagation path of the mobile station apparatus performs discrete frequency band allocation. When precoding is applied in a unit of a certain frequency bandwidth, and when the transmission path of the transmission device is discretely assigned, when maintaining a constant reception quality, the frequency band is discretely assigned to the mobile station device and transmitted. A single precoding is applied to all frequency bands used by the device.
3) The base station apparatus continuously allocates frequency bands to the mobile station apparatus when a certain reception quality cannot be obtained even though the propagation path of the mobile station apparatus performs discrete frequency band allocation. When precoding is applied in units of a certain frequency bandwidth and when a transmission path of a transmission apparatus is discretely allocated, a constant reception quality is maintained. In this case, a frequency band is discretely allocated to the mobile station apparatus. Precoding determined in advance in units of frequency bandwidths is applied. In a frequency band that includes a base station device and a mobile station device and is used for data transmission by a mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency to the transmission device. A base station apparatus in a wireless communication system for notifying band allocation information,
A base station apparatus characterized by changing a method of assigning frequency bands to be allocated to the mobile station apparatus and switching a precoding application method. In a frequency band that includes a base station device and a mobile station device and is used for data transmission by a mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency to the transmission device. A mobile station apparatus in a wireless communication system for notifying band allocation information,
A mobile station apparatus, wherein data transmission is performed by changing a precoding application method based on information on an allocated frequency band and precoding application or precoding pattern information. In a frequency band that includes a base station device and a mobile station device and is used for data transmission by a mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency to the transmission device. A communication method on the base station apparatus side in a wireless communication system for notifying band allocation information,
When the frequency band used for data transmission by the mobile station device is narrow, the mobile station device continuously assigns the frequency band to the mobile station device, and performs precoding in a certain frequency bandwidth unit. When the frequency band used for is wide, a communication method is characterized in that frequency bands are discretely allocated to the mobile station apparatus and precoding is not applied. In a frequency band that includes a base station device and a mobile station device and is used for data transmission by a mobile station device that is a transmission device, the base station device that is a reception device has a continuous frequency band or a discrete frequency to the transmission device. A communication method on a mobile station apparatus side in a wireless communication system for notifying band allocation information,
When the frequency band used for data transmission is narrow, the frequency band is continuously allocated from the base station device and precoding is performed in a certain frequency bandwidth unit, and when the frequency band used for data transmission is wide, A communication method characterized in that frequency bands are discretely allocated from the base station apparatus and precoding is not applied.   A program for causing a computer to execute the communication method according to claim 15 or 16.

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