JP5824586B1 - Base station, radio communication system, and communication control method - Google Patents

Abstract

An operation for assigning unnecessary radio resources is suppressed. A base station eNB selects a target user device (TUE) to which a radio resource is to be allocated from a plurality of user devices (UE), and assigns a control resource that is a radio resource for control. The control resource allocating unit 244 that executes the data resource allocation, and the data resource allocating unit 246 that performs the allocation of the data resource that is the radio resource for data. The user apparatus selection unit 242 calculates the provisional control resource amount corresponding to the control resource to be allocated to each user apparatus UE based on the reception quality reported from each user apparatus, and determines whether or not the provisional control resource amount can be secured. A determination is made for each user device, and the user device determined to be able to secure the provisional control resource amount is selected as the target user device. [Selection] Figure 9

Description

  The present invention relates to a base station, a wireless communication system, and a communication control method.

  In the LTE (Long Term Evolution) standard, which is one of the cellular wireless communication standards, wireless signals (data signals and control signals) are transmitted and received via various physical channels. For downlink data transmission from the base station to the user apparatus, a physical downlink shared channel (PDSCH) is used. For uplink data transmission from the user apparatus to the base station, a physical uplink shared channel (PUSCH) is used. Hereinafter, transmitting a radio signal via a channel may be simply expressed as “transmitting a channel”.

  The scheduling information for controlling the above data transmission / reception is transmitted from the base station to the user apparatus via a physical downlink control channel (PDCCH, Physical Downlink Control CHannel). The PDCCH includes a C-RNTI (Cell-Radio Network Temporary Identifier) that is an identifier of the destination user apparatus. The user apparatus determines whether or not there is radio resource allocation for the user apparatus depending on whether or not the C-RNTI addressed to the user apparatus is included in the transmitted PDCCH.

  As scheduling information related to downlink transmission from the base station to the user apparatus, downlink scheduling information (DL Scheduling Information) is transmitted to the user apparatus. The downlink scheduling information indicates information regarding the position of RB (Resource Block) allocated to the user apparatus in PDSCH and the signal format (modulation scheme, coding rate, etc.). As shown in FIG. 1, the user apparatus receives PDSCH (downlink data signal) based on downlink scheduling information included in PDCCH. PDCCH and PDSCH are transmitted in the same subframe.

  As scheduling information related to uplink transmission from the user apparatus to the base station, an uplink scheduling grant (UL Scheduling Grant) is transmitted to the user apparatus. The uplink scheduling grant indicates information on the position and signal format of the RB allocated to the user apparatus in the PUSCH. As shown in FIG. 2, the user apparatus transmits PUSCH (uplink data signal) based on uplink scheduling permission. Note that the PUSCH transmission is executed after a predetermined time (for example, 4 milliseconds) has elapsed since the user apparatus received the PDCCH.

  FIG. 3 is an outline of a processing flow of downlink transmission (PDCCH / PDSCH transmission). Prior to transmission of actual radio signals (physical channels), radio resources are allocated to each user apparatus. In this example, each step is executed sequentially (serially).

  First, the base station selects a target user apparatus to which downlink data is to be transmitted (S10). In this example, four user apparatuses UE-0, UE-1, UE-2, and UE-3 are selected as targets.

  Next, the base station secures a PDCCH resource to be allocated to the user apparatus (S20). As a minimum allocation unit of PDCCH resources, CCE (Control Channel Element) is defined in the LTE standard. The CCE is a radio resource including nine REGs (Resource Element Groups). One REG is a radio resource including four REs (Resource Elements).

  The PDCCH resource cannot always be secured for all user apparatuses selected in step S10. This is because the total number of CCEs (the size of the control channel region in which CCEs in a subframe are arranged) and the transmission power that can be used for CCE transmission are limited. In this example, it is assumed that PDCCH resources can be secured for UE-0, UE-1, and UE-2, and PDCCH resources cannot be secured for UE-3.

  After that, the base station reserves the PDSCH resource only for the user apparatus that can secure the PDCCH resource in step S20 (S30). This is because if there is no scheduling information indicated in the PDCCH, the user apparatus does not receive the data signal even if the base station transmits the PDSCH, and thus the reserved PDSCH resource is wasted. In this example, PDSCH resources are reserved only for UE-0, UE-1, and UE-2 for which PDCCH resources are reserved.

  The base station transmits a PDCCH (control signal) and a PDSCH (data signal) using the PDCCH resource secured in step S20 and the PDSCH resource secured in step S30 (S40). In this example, transmission of PDCCH and PDSCH is performed to UE-0, UE-1, and UE-2. Note that transmission to UE-3 is performed in the following subframes.

  As described above, FIG. 3 illustrates downlink transmission, but the same processing flow can be applied to uplink transmission (PUSCH transmission) (note that the user apparatus executes PUSCH transmission instead of the base station). Is naturally understood).

  According to the radio resource allocation described above, the process of securing the radio resource for data (step S30) is executed after the process of securing the radio resource for control (step S20) (that is, the sequential radio resource allocation) Because radio resource allocation is performed), the processing time may be excessive. In order to suppress the increase in the processing time as described above, it is preferable to execute the parallel radio resource allocation operation shown in FIG.

  Similar to the sequential radio resource allocation, the base station selects a target user apparatus UE to transmit downlink data (S12). Next, the base station reserves (assigns) a PDCCH resource (control resource) and a PDSCH resource (data resource) in parallel for the selected user apparatus (S22, S32). The base station transmits the PDCCH and PDSCH to each user apparatus using the reserved resources (S42).

JP 2011-41193 JP

  In the radio resource allocation technique as described above, the PDCCH resource (control resource) is limited as compared with the PDSCH resource (data resource), and thus cannot always be secured for all selected user apparatuses. . The operation of securing radio resources for a user apparatus for which PDCCH resources (control resources) cannot be secured is useless, and PDSCH resources that cannot be used (that is, there is no corresponding PDCCH resource) may be secured. The same relationship holds for uplink transmission (that is, for PDCCH resources and PUSCH resources).

  In view of the above circumstances, an object of the present invention is to suppress unnecessary radio resource assignment operations.

  The base station of the present invention includes: a user device selection unit that selects a target user device to which a radio resource is to be allocated from a plurality of user devices; and allocation of a control resource that is the radio resource for control to the target user device And a data resource allocating unit for allocating a data resource that is the radio resource for data to the target user apparatus. Whether the user device selection unit can calculate the provisional control resource amount corresponding to the control resource to be allocated to each user device based on the reception quality reported from each user device, and can secure the provisional control resource amount Is determined for each user device, and the user device determined to be able to secure the provisional control resource amount is selected as the target user device.

  The radio communication system of the present invention includes a user device selection unit that selects a target user device to which radio resources are to be allocated from a plurality of user devices, and a control resource that is the radio resource for control with respect to the target user device. A control resource allocating unit that executes allocation, and a data resource allocating unit that allocates data resources that are the radio resources for data to the target user apparatus. Whether the user device selection unit can calculate the provisional control resource amount corresponding to the control resource to be allocated to each user device based on the reception quality reported from each user device, and can secure the provisional control resource amount Is determined for each user device, and the user device determined to be able to secure the provisional control resource amount is selected as the target user device.

  The communication control method of the present invention selects a target user device to which a radio resource is to be allocated from a plurality of user devices, and assigns a control resource that is the radio resource for control to the target user device. And performing allocation of data resources, which are the radio resources for data, to the target user apparatus. In selecting the target user device, a provisional control resource amount corresponding to the control resource to be allocated to each user device is calculated based on reception quality reported from each user device, and the provisional control resource amount is It is determined for each user device whether or not it can be secured, and the user device that is determined to be able to secure the provisional control resource amount is selected as the target user device.

  According to the present invention, unnecessary radio resource assignment operations are suppressed.

It is the schematic which shows transmission of PDCCH and PDSCH. It is the schematic which shows transmission of PDCCH and PUSCH. It is the schematic of the processing flow of downlink transmission. It is a figure which shows the example of the allocation operation | movement of a parallel radio | wireless resource. 1 is a schematic diagram of a wireless communication system according to a first embodiment. It is a figure which shows the example of a radio | wireless frame. It is a figure which shows the channel area | region which a downlink sub-frame contains. It is a block diagram of the configuration of the user device according to the first embodiment. It is a block diagram of the configuration of the base station according to the first embodiment. It is an operation | movement flow which shows an example of the radio | wireless resource allocation of 1st Embodiment. It is a flow which shows the detailed operation | movement of step S100DL of FIG. It is a flow which shows the detailed operation | movement of step S200 of FIG. It is an operation | movement flow which shows an example of the radio | wireless resource allocation of 2nd Embodiment. It is an operation | movement flow which shows an example of the radio | wireless resource allocation of 2nd Embodiment.

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

1. First Embodiment 1 (1). Overview of Radio Communication System FIG. 5 is a schematic diagram showing a radio communication system CS according to the first embodiment of the present invention. The radio communication system CS includes a base station eNB and user apparatuses UE (UE-0, UE-1, UE-2, UE-3, ...). The base station eNB is connected to a core network (not shown) including a MME (Mobile Management Entity) that is a control node and a gateway that is a connection point with an external network.

  Each element in the radio communication system CS performs communication in accordance with a predetermined access technology (Access Technology), for example, LTE / SAE (Long Term Evolution / System Architecture Evolution) standard included in 3GPP (Third Generation Partnership Project) standard. A method of radio communication between the user apparatus UE and the base station eNB is arbitrary. For example, OFDMA (Orthogonal Frequency Division Multiple Access) is adopted in the downlink, and SC-FDMA (Single-Carrier Frequency Division Multiple Access) is adopted in the uplink.

1 (2). Radio resource In radio communication between the base station eNB and the user apparatus UE, a radio frame F is used as a spatio-temporal radio resource. FIG. 6 illustrates the configuration of the radio frame F. The base station eNB and the user apparatus UE transmit various radio signals (control channel, data channel, etc.) mounted on the radio frame F. With respect to the time axis direction, one radio frame F includes 10 subframes SF. One subframe SF includes two slots, and each slot includes a plurality of symbols (for example, 7, 6, or 3). The time length of each subframe SF is 1 millisecond, and the time length of one radio frame F is 10 milliseconds. As shown in FIG. 6, any subframe number from # 0 to # 9 is assigned to each subframe SF in the order of transmission.

  As shown in FIG. 7, one downlink subframe DSF includes a control channel region (control resource) used for PDCCH transmission and a shared channel region (data resource) used for PDSCH transmission. The control channel region includes a plurality of CCEs (Control Channel Elements) that are units of PDCCH allocation. One unit of CCE is mapped over the entire control channel region. The control channel region is located at the beginning of the downlink subframe DSF. The data channel region includes a plurality of RBs (Resource Blocks) that are units of PDSCH allocation. The shared channel region is located after the control channel region. The resource amount of the control channel region is limited compared to the resource amount of the shared channel region.

  According to the 3GPP standard, the number of CCEs allocated to one user equipment UE in one downlink subframe DSF is any one of 1, 2, 4, and 8, and PDCCH format 0, PDCCH format 1, and PDCCH format, respectively. 2, PDCCH format 3 is defined. The above number of CCEs per user apparatus UE is also referred to as an aggregation level.

  A CCE index starting from 0 is assigned to CCEs in the control channel region, such as CCE0, CCE1, CCE2,. According to the 3GPP standard, CCE (CCE index) that can be used for a certain PDCCH format is different for each user apparatus UE (that is, C-RNTI) and for each subframe SF. For example, CCE0,1, ..., 7 can be used for PDCCH format 0 and CCE {4,5}, {6,7}, ... can be used for PDCCH format 1 for a certain user equipment UE-0 and a certain subframe SF. , {16, 17} can be used, CCE {0, 1, 2, 3}, {4, 5, 6, 7} can be used for PDCCH format 2, and CCE {8, 9, ..., 15}, {16, 17, ..., 23} can be used.

  Transmission of radio signals requires transmission power in addition to spatio-temporal resources (time and frequency band). That is, transmission power is another aspect of radio resources. The PDCCH resource (control resource) includes a CCE resource and a transmission power resource. Therefore, even if CCE (CCE resource) that is a spatio-temporal resource is secured, if the transmission power (transmission power resource) is not secured, the base station eNB cannot transmit the PDCCH.

  According to the 3GPP standard, the transmission power of PDCCH is arbitrary. The transmission power of the PDCCH is determined based on, for example, a CQI (Channel Quality Indicator) that is a reception quality of the downlink channel fed back from the user apparatus UE. In general, the base station eNB transmits the PDCCH with lower transmission power as the CQI indicates higher reception quality. The transmission power of PDCCH varies depending on the number of CCEs to be transmitted. As described above, since the CCE is mapped over the entire control channel region, the transmission of the PDCCH is impossible when there is even one symbol with insufficient transmission power.

1 (3). Configuration of each element 1 (3) -1. Configuration of User Device FIG. 8 is a block diagram illustrating a configuration of the user device UE according to the present embodiment. The user apparatus UE includes a radio communication unit 110, a storage unit 120, and a control unit 130. Illustrations of an output device that outputs audio, video, and the like and an input device that receives an instruction from the user are omitted for the sake of convenience. The wireless communication unit 110 is an element for performing wireless communication with the base station eNB, such as a transmission / reception antenna, a receiving circuit that receives a radio signal (radio wave) and converts it into an electrical signal, a control signal / data signal, etc. A transmission circuit that converts an electrical signal into a radio signal (radio wave) and transmits the signal. The storage unit 120 stores information related to communication control and a computer program described later.

  The control unit 130 includes a CQI reporting unit 132, a downlink receiving unit 134, and an uplink transmitting unit 136. The CQI report unit 132 measures and reports CQI indicating downlink reception quality from the base station eNB. The downlink receiving unit 134 receives the PDCCH, and receives the PDSCH according to the downlink scheduling information indicated by the received PDCCH. The uplink transmission unit 136 transmits the PUSCH according to the uplink scheduling permission (transmission instruction) indicated by the PDCCH.

  The control unit 130 and each element in the control unit 130 are realized by a CPU (Central Processing Unit) in the user apparatus UE executing a computer program stored in the storage unit 120 and functioning according to the computer program. It is a functional block.

1 (3) -2. Configuration of Base Station FIG. 9 is a block diagram showing the configuration of the base station eNB according to this embodiment. The base station eNB includes a radio communication unit 210, a network communication unit 220, a storage unit 230, and a control unit 240. The radio communication unit 210 is an element for executing radio communication with the user apparatus UE, and includes a transmission / reception antenna, a reception circuit, and a transmission circuit. The network communication unit 220 is an element for executing communication with other nodes in the core network. The storage unit 230 stores information related to communication control and a computer program to be described later.

  The control unit 240 includes a user equipment selection unit 242, a control resource allocation unit 244, a data resource allocation unit 246, a downlink transmission unit 248, and an uplink reception unit 250. The user device selection unit 242 selects a target user device TUE to which radio resources are to be allocated from a plurality of user devices UE. The control resource allocation unit 244 allocates a control resource (PDCCH) to the target user apparatus TUE. The data resource allocation unit 246 allocates data resources (PDSCH, PUSCH) to the target user apparatus TUE. The control resource allocation by the control resource allocation unit 244 and the data resource allocation by the data resource allocation unit 246 can be executed in parallel. The downlink transmission unit 248 transmits a control signal (for example, PDCCH) and a data signal (for example, PDSCH) to the user apparatus UE (target user apparatus TUE) based on the above resource allocation (scheduling). The uplink receiving unit 250 receives a radio signal (for example, PUSCH) transmitted from the user apparatus UE.

  Each element in the control unit 240 and the control unit 240 is a functional block realized by the CPU in the base station eNB executing the computer program stored in the storage unit 230 and functioning according to the computer program.

1 (4). FIG. 10 is an operation flow illustrating an example of radio resource allocation according to the present embodiment. In this operation flow, downlink radio resource allocation and uplink radio resource allocation are integrated. This operation flow is repeatedly executed for each subframe SF.

  The user apparatus selection unit 242 of the base station eNB selects a target user apparatus TUE that should perform downlink transmission (S100DL). Moreover, the user apparatus selection part 242 selects the target user apparatus TUE which should perform an uplink transmission instruction | indication (S100UL). The above steps S100DL and S100UL are executed in parallel.

  FIG. 11 is a flowchart showing the detailed operation of step S100DL. Schematically, in step S100DL, for each user apparatus UE capable of downlink transmission, it is simply determined whether there is an assignable control resource.

  As described above, the CCE that can be used for a certain PDCCH format is limited by the CCE index. Therefore, to determine a control resource to be allocated to a certain user apparatus UE, it is necessary to consider a free (that is, usable) CCE index. However, the control resource allocation operation considering the free CCE index corresponding to the PDCCH format used by the user apparatus UE has a large processing load and a long time.

Therefore, in step S100DL of the present embodiment, whether or not control resources can be allocated is simply determined based only on the quantitative viewpoint of control resources. That is, in step S100DL, control is actually performed based on whether or not the provisional control resource amount N _{PDCCH, i} corresponding to the control resource that should be originally allocated to the user apparatus UE, calculated based on CQI (reception quality). A target user apparatus TUE to which resources are to be allocated is selected.

The user apparatus selection unit 242 calculates a control resource amount (PDCCH resource amount) N _{PDCCH, total, DL} used for downlink transmission according to the following equation (1) (S102DL).
N _{PDCCH, total, DL} = α _{PDCCH, DL} · N _{PDCCH, total} (1)

Here, N _{PDCCH, total} is the total amount of control resources (total number of CCEs) that can be used in the current subframe SF. Α _{PDCCH, DL} is a weighting coefficient that takes a value from 0 to 1, and is a value indicating how much of N _{PDCCH, total} is used for downlink transmission. α _{PDCCH and DL} may be fixedly set according to the downlink traffic ratio, or dynamically according to the number of users (the number of user apparatuses UE) that perform downlink communication in the current subframe SF. May be set.

The user apparatus selection unit 242 initializes 0 to the index i of the user apparatus UE that is the target of the resource allocation loop process (steps S106DL to S120DL) (S104DL). In the following example, the user apparatus UE specified by the index i is denoted as “UE-i”. The index i indicates the priority of resource allocation. Also, the user apparatus selection unit 242 initializes N _{PDCCH, remain} indicating the remaining amount of control resources that can be allocated to the user apparatus UE according to the following equation (2) (S104DL).
N _{PDCCH, remain} = N _{PDCCH, total, DL} (2)

Based on the CQI reported from the CQI reporting unit 132 of the user apparatus UE-i, the user apparatus selection unit 242 determines the number of PDCCHs to be used for the user apparatus UE-i in the current subframe SF n _{CCE, i} And the power correction coefficient β _{P, i} are calculated (S106DL). The CQI used in step S106DL is preferably a wideband CQI. The power correction coefficient β _{P, i} is a multiplier (amplification magnification) for the rated transmission power. The setting method of each value is arbitrary, but for example, the higher the reception quality indicated by the CQI _{, the} smaller the number of PDCCH n _{CCE, i} is set, and the lower the power correction coefficient βP _{, i} is.

The user apparatus selection unit 242 calculates the temporary control resource amount N _{PDCCH, i} corresponding to the control resource to be allocated to the user apparatus UE-i according to the following equation (3) (S108DL).
N _{PDCCH, i} = n _{CCE, i} · β _{P, i} (3)

The user apparatus selection unit 242 determines whether or not the provisional control resource amount N _{PDCCH, i} can be secured for the user apparatus UE-i (S110DL). That is, the user apparatus selection unit 242 determines whether or not the provisional control resource amount N _{PDCCH, i} is less than or equal to the remaining resource amount N _{PDCCH, remain} (whether or not equation (4) is satisfied).
N _{PDCCH, i} ≤ N _{PDCCH, remain} (4)

When it is determined that the provisional control resource amount N _{PDCCH, i} can be secured (S110DL: YES), the user apparatus selection unit 242 selects the user apparatus UE-i as the target user apparatus TUE (S112DL), and the user apparatus UE− The provisional control resource amount N _{PDCCH, i} to be secured for i is subtracted from the remaining resource amount N _{PDCCH, remain} (S114DL). On the other hand, the user apparatus selection unit 242 does not select the user apparatus UE-i determined to be unable to secure the provisional control resource amount N _{PDCCH, i} as the target user apparatus TUE (S116DL).

  The user apparatus selection unit 242 increments the index i in order to shift the process to the user apparatus UE- (i + 1) having the next priority (S118DL). When the incremented index i becomes equal to the number M of user apparatuses UE that can perform downlink transmission (S120DL: YES), step S100DL ends. If not (S120DL: NO), the process returns to step S106DL and the resource allocation loop process continues. Through the loop processing described above, for each user apparatus UE-i, the presence or absence of an assignable control resource is simply determined.

The above-described selection processing of the user apparatus UE related to the downlink (step S100DL including steps S102DL to S120DL) includes the control resource amount N _{PDCCH, total, DL} for downlink transmission as the control resource amount N _PDCCH for uplink transmission instruction _{, In addition} to replacing _{total and UL} , the weighting coefficient α _{PDCCH and DL} for downlink transmission is replaced with the weighting coefficient α _{PDCCH and UL} for uplink transmission instruction, thereby selecting the user apparatus UE related to the uplink (S100UL) The same applies to. With respect to the above values, the following equation (5) is established in the same manner as the above-described equation (1).
N _{PDCCH, total, UL} = α _{PDCCH, UL} · N _{PDCCH, total} (5)

Here, α _{PDCCH, UL} is a weighting coefficient taking a value from 0 to 1, and is a value indicating how much of N _{PDCCH, total} is used for the uplink transmission instruction. α _{PDCCH, UL} may be fixedly set according to the uplink traffic ratio, or may be dynamically set according to the number of users performing uplink communication in the current subframe SF.

  The PDCCH is used for both downlink scheduling information (downlink transmission) and uplink scheduling permission (uplink transmission instruction). Therefore, the control resource allocation unit 244 reserves downlink control resources (PDCCH) for both the downlink target user apparatus TUE selected in step S100DL and the uplink target user apparatus TUE selected in step S100UL. (S200).

  FIG. 12 is a flowchart showing the detailed operation of step S200. First, the control resource allocation unit 244 initially sets 0 to the index j of the user apparatus UE (target user apparatus TUE) that is the target of the actual control resource allocation loop process (S204 to S226) (S202). In the following example, the user apparatus UE specified by the index j is denoted as “UE-j”. The index j indicates the priority of control resource allocation.

  The control resource allocation unit 244 determines a PDCCH format (aggregation level) to be used by the user apparatus UE-j based on the CQI reported from the CQI report unit 132 of the user apparatus UE-j (S204). The CQI used in step S204 is preferably a wideband CQI. For example, the control resource allocation unit 244 selects a PDCCH format having a smaller number of CCEs as the CQI indicates higher reception quality.

  The control resource allocation unit 244 determines whether there is a free CCE resource having a CCE index corresponding to the PDCCH format to be used by the user apparatus UE-j (S206).

  When there is no free CCE resource (S206: NO), the control resource allocation unit 244 determines whether or not the PDCCH format to be used by the user apparatus UE-j can be changed (S208). When the PDCCH format can be changed (S208: YES), the control resource allocation unit 244 changes the PDCCH format (S210), and executes the determination in step S206 again. When the PDCCH format is not changeable (S208: NO), the control resource allocation unit 244 determines that securing of control resources for the user apparatus UE-j has failed (S222).

  When there is a free CCE resource (S206: YES), the control resource allocation unit 244 temporarily reserves the free CCE resource (S212), and based on the CQI of the user apparatus UE-j and the number of CCE resources, The transmission power is determined (S214).

  When transmitting the PDCCH with the determined transmission power, the control resource allocation unit 244 determines whether there is a PDCCH symbol exceeding the maximum transmission power (S216). When there is no PDCCH symbol exceeding the maximum transmission power (S216: NO), the control resource allocation unit 244 controls the control resource (that is, the CCE resource temporarily reserved in step S212 and the transmission power resource determined in step S214). Is secured for the user apparatus UE-j (S218).

  On the other hand, when there is a PDCCH symbol exceeding the maximum transmission power (S216: YES), the PDCCH cannot be transmitted, so the control resource allocation unit 244 releases the CCE resource temporarily reserved in step S212 (S220), and the user apparatus It is determined that securing of control resources for UE-j has failed (S222).

  The control resource allocation unit 244 increments the index j in order to shift the process to the user apparatus UE- (j + 1) having the next priority (S224). If the incremented index j is equal to the number K of target user apparatuses TUE (S226: YES), step S200 ends. If not (S226: NO), the process returns to step S204, and the control resource allocation loop process continues. Through the above loop processing, allocation of control resources (CCE resources and transmission power resources) is attempted for each target user apparatus TUE.

  The data resource allocation unit 246 reserves a downlink data resource (PDSCH) for the downlink target user apparatus TUE selected in step S100DL (S300DL). Also, the data resource allocation unit 246 reserves an uplink data resource (PUSCH) for the uplink target user apparatus TUE selected in step S100UL (S300UL).

  The above step S200 and steps S300DL and S300UL are executed in parallel.

  The downlink transmission unit 248 of the base station eNB transmits the PDCCH and PDSCH using the downlink radio resources (control resources and data resources) secured in steps S200 and S300DL (S400). Further, the uplink receiving unit 250 of the base station eNB receives the PUSCH transmitted from the uplink transmitting unit 136 of the user apparatus UE based on the uplink scheduling permission in the previous subframe SF.

1 (5). Advantageous Effects of the Present Embodiment According to the configuration of the present embodiment described above, unnecessary radio resource allocation operations are suppressed. That is, since a user apparatus UE that can secure a simply calculated provisional control resource amount corresponding to a control resource to be allocated is selected as a radio resource allocation target (target user apparatus TUE), a user other than the target user apparatus TUE is selected. The actual radio resource allocation operation (steps S200, S300DL, S300UL) is not executed for the device UE.

2. Second Embodiment A second embodiment of the present invention will be described below. In each embodiment illustrated below, about the element which an effect | action and a function are equivalent to 1st Embodiment, the code | symbol referred by the above description is diverted and each description is abbreviate | omitted suitably.

  In 1st Embodiment, selection of the target user apparatus TUE which should perform downlink transmission (step S100DL), and selection of the target user apparatus TUE which should perform an uplink transmission instruction | indication (step S100UL) are performed in parallel. . In the second embodiment, the above steps are executed in series.

2 (1). Wireless resource allocation 2 (1) -1. Case where User Device for Downlink Transmission is Selected First FIG. 13 is an operation flow illustrating an example of radio resource allocation according to the present embodiment. In the example of FIG. 13, the target user apparatus TUE that should perform downlink transmission is selected first.

  The user apparatus selection unit 242 of the base station eNB selects a target user apparatus TUE that should perform downlink transmission (S100DL). The operation of step S100DL is the same as that of the first embodiment. Then, the user apparatus selection part 242 selects the target user apparatus TUE which should perform an uplink transmission instruction | indication (S100UL).

The operation of step S100UL is the same as that of the first embodiment except for the following. The user equipment selection unit 242 calculates the control resource amount (PDCCH resource amount) N _{PDCCH, total, UL} used for the uplink transmission instruction according to the following equation (6) (S102UL).
N _{PDCCH, total, UL} = γ _{PDCCH, UL.} (N _{PDCCH, total−} N _{PDCCH, DL} ) (6)

Here, N _{PDCCH, DL} is a control resource amount used in downlink transmission, and is a total value of the provisional control resource amounts N _{PDCCH, i} assigned to each user apparatus UE-i in step S100DL. Further, γ _{PDCCH, UL} is a weighting coefficient that takes a value from 0 to 1, and can be set fixedly or dynamically as in the case of α _{PDCCH, UL} .

2 (1) -2. Case where target user apparatus of uplink transmission instruction is first selected FIG. 14 is an operation flow illustrating an example of radio resource allocation according to the present embodiment. In the example of FIG. 14, the target user apparatus TUE that should execute the uplink transmission instruction is selected first.

  The user apparatus selection unit 242 of the base station eNB selects a target user apparatus TUE that should execute an uplink transmission instruction (S100UL). The operation in step S100UL is the same as that in the first embodiment. Then, the user apparatus selection part 242 selects the target user apparatus TUE which should perform downlink transmission (S100DL).

The operation of step S100DL is the same as that of the first embodiment except for the following. The user apparatus selection unit 242 calculates a control resource amount (PDCCH resource amount) N _{PDCCH, total, DL} used for downlink transmission according to the following equation (7) (S102DL).
N _{PDCCH, total, DL} = γ _{PDCCH, DL.} (N _{PDCCH, total-} N _{PDCCH, UL} ) (7)

Here, N _{PDCCH, UL} is a control resource amount used in the uplink transmission instruction, and is a total value of the provisional control resource amounts N _{PDCCH, i} allocated to each user apparatus UE-i in step S100UL. . Further, γ _{PDCCH, DL} is a weighting coefficient that takes a value from 0 to 1, and can be set fixedly or dynamically as in the case of α _{PDCCH, DL} .

2 (2). Advantageous Effects of the Present Embodiment According to the configuration of the present embodiment described above, unnecessary radio resource assignment operations are suppressed, as in the first embodiment. Also, one of the control resource amount used for the uplink transmission instruction and the control resource amount used for the downlink transmission is determined first, and the other is determined based on the determined value. Therefore, the latter (the other) control resource amount can be determined more accurately.

3. Modifications The above embodiment can be variously modified. Specific modifications are exemplified below. Two or more aspects arbitrarily selected from the above embodiments and the following examples can be appropriately combined as long as they do not contradict each other.

3 (1). Modification 1
The priority (index i, j) of resource allocation in steps S100DL, S100UL, and S200 can be determined by any method. For example, a higher priority may be assigned to a plurality of user apparatuses UE in descending order of reception quality, or a higher priority may be assigned in descending order of transmission data amount. The above priorities are preferably determined before a radio resource allocation operation (for example, FIG. 10, FIG. 13, FIG. 14) starts.

3 (2). Modification 2
At least one of the user apparatus selection unit 242, the control resource allocation unit 244, and the data resource allocation unit 246 may be implemented in an apparatus other than the base station eNB included in the radio communication system CS.

3 (3). Modification 3
In the above embodiment, the control resource (PDCCH resource) allocation operation and the data resource (PDSCH resource, PUSCH resource) allocation operation are executed in parallel. However, the control resource allocation operation and the data resource allocation operation may be executed in series. For example, a data resource allocation operation may be performed after the control resource allocation operation, or a control resource allocation operation may be performed after the data resource allocation operation.

3 (4). Modification 4
The user apparatus UE is an arbitrary apparatus capable of wireless communication with the base station eNB. The user apparatus UE may be, for example, a mobile phone terminal such as a feature phone or a smartphone, a desktop personal computer, a notebook personal computer, a UMPC (Ultra-Mobile Personal Computer), or a portable game machine. Other wireless terminals may be used.

3 (5). Modification 5
Each function executed by the CPU in each element (user apparatus UE, base station eNB) in the radio communication system CS may be executed by hardware instead of the CPU, for example, an FPGA (Field Programmable Gate Array), You may perform with programmable logic devices, such as DSP (Digital Signal Processor).

  UE ...... User equipment 110 ... Radio communication unit 120 ... Storage unit 130 ... Control unit 132 ... CQI report unit 134134 Downlink reception unit 136 ... Uplink transmission unit eNB ... base station, 210 ... wireless communication unit, 220 ... network communication unit, 230 ... storage unit, 240 ... control unit, 242 ... user device selection unit, 244 ... control resource allocation unit, 246 ... data Resource allocation unit, 248 ... downlink transmission unit, 250 ... uplink reception unit, CS ... wireless communication system, F ... radio frame, SF ... subframe, UE ... user equipment.

Claims (8)

A user device selection unit that selects a target user device to which radio resources are to be allocated from a plurality of user devices;
A control resource allocation unit that allocates a control resource that is the radio resource for control to the target user device;
A data resource allocation unit that performs allocation of data resources that are the radio resources for data to the target user device, and
The user device selection unit is
A provisional control resource amount corresponding to the control resource to be allocated to each user device is calculated based on reception quality reported from each user device, and whether or not the provisional control resource amount can be secured for each user device. The base station selects the user apparatus determined to be able to secure the provisional control resource amount as the target user apparatus. The control resource allocation unit, for each target user device,
Determining a PDCCH format indicating the number of CCE resources included in the control resource to be used by the target user apparatus based on the reception quality reported from the target user apparatus;
When it is determined that there is a free CCE resource corresponding to the PDCCH format to be used by the user apparatus, the free CCE resource is temporarily reserved,
Determining the transmission power of the PDCCH transmitted using the control resource based on the reception quality and the number of free CCE resources;
2. When it is determined that the maximum transmission power does not exceed even if the PDCCH is transmitted with the transmission power, the vacant CCE resource and the transmission power that are temporarily secured are secured for the user apparatus. Base station. The user device selection unit is
In parallel, selecting the target user apparatus from a plurality of user apparatuses capable of downlink transmission and selecting the target user apparatus from a plurality of user apparatuses capable of instructing uplink transmission The base station according to claim 1 or 2. The user device selection unit is
The base station according to claim 1 or 2, wherein after selecting the target user apparatus from a plurality of user apparatuses capable of downlink transmission, the target user apparatus is selected from a plurality of user apparatuses capable of instructing uplink transmission. The user device selection unit is
The base station according to claim 1 or 2, wherein the target user apparatus is selected from a plurality of user apparatuses capable of downlink transmission after selecting the target user apparatus from a plurality of user apparatuses capable of performing an uplink transmission instruction. The base station according to claim 1, wherein the control resource allocation by the control resource allocation unit and the data resource allocation by the data resource allocation unit are executed in parallel. A user device selection unit that selects a target user device to which radio resources are to be allocated from a plurality of user devices;
A control resource allocation unit that allocates a control resource that is the radio resource for control to the target user device;
A data resource allocation unit that performs allocation of data resources that are the radio resources for data to the target user device, and
The user device selection unit is
A provisional control resource amount corresponding to the control resource to be allocated to each user device is calculated based on reception quality reported from each user device, and whether or not the provisional control resource amount can be secured for each user device. A wireless communication system that selects the user device that has been determined to be able to secure the provisional control resource amount as the target user device. Selecting a target user device to which radio resources should be allocated from a plurality of user devices;
Assigning control resources, which are the radio resources for control, to the target user device;
Allocating data resources that are the radio resources for data to the target user device,
In selecting the target user device,
A provisional control resource amount corresponding to the control resource to be allocated to each user device is calculated based on reception quality reported from each user device, and whether or not the provisional control resource amount can be secured for each user device. The communication control method of selecting the user device determined to be able to secure the provisional control resource amount as the target user device.

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