JP2015139101A - User terminal, radio communication system, and transmission power control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately perform uplink transmission power control for each sub-frame set obtained by grouping optional sub-frames in a radio frame.SOLUTION: A user terminal which transmits an uplink signal includes: a receiving unit for receiving, from a radio base station, configuration information of at least one sub-frame set constituted by grouping the sub-frames in the radio frame; and a control unit for controlling the transmission power of the uplink signal for each sub-frame set, on the basis of a control parameter. The control unit resets the control parameter when the sub-frame set is changed based on the configuration information.

Description

  The present invention relates to uplink signal transmission power control in a wireless communication system.

  Conventionally, as a duplex method in a radio communication system, frequency division duplex (FDD) that divides uplink (UL) and downlink (DL) by frequency, and time division duplex that divides uplink and downlink by time. (TDD) is known (for example, Non-Patent Document 1). In FDD, uplink signals and downlink signals are transmitted and received at different frequencies. On the other hand, in TDD, uplink signals and downlink signals are transmitted and received at different times.

  In addition, in a wireless communication system using TDD such as LTE (Long Term Evolution), a UL-DL configuration (UL-DL Configuration) indicating a configuration (ratio) between an uplink subframe and a downlink subframe in a radio frame is defined. Is done. For example, in FIG. 1, seven UL-DL configurations 0-6 indicating configurations of the uplink subframe and the downlink subframe are shown.

3GPP TS 36.300 “Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2”

  In general, UL and DL traffic is asymmetric. Further, the traffic ratio of UL and DL in a predetermined period is not constant, but varies with time or place. For this reason, in a radio communication system using TDD, radio resources are effectively used by dynamically changing the UL / DL resource configuration in a certain cell (transmission point, radio base station) according to traffic fluctuations. Is desired.

  Therefore, in a future wireless communication system using TDD, such as LTE Advanced (LTE-A), which succeeds LTE, the UL-DL configuration shown in FIG. 1 is dynamically changed in order to obtain a traffic adaptive gain ( Dynamic TDD, Rel.12 eIMTA (also called enhanced Interference Mitigation and Traffic Adaptation, etc.) has been studied.

  On the other hand, in dynamic TDD, when different UL-DL configurations are used between adjacent radio base stations, inter-base station interference is larger in subframes having different transmission directions between the radio base stations than in the same subframe. (Inter-eNB Interference, also called Inter-cell Interference) is assumed to occur. For this reason, it has been studied to perform independent uplink transmission power control by grouping subframes having different transmission directions between radio base stations and the same subframe.

  Further, the present invention is not limited to the case where the dynamic TDD described above is applied, and it is assumed that the influence of interference differs for each arbitrary subframe grouped in a radio frame (hereinafter referred to as a subframe set). For this reason, it is desired to appropriately perform uplink transmission power control for each subframe set obtained by grouping arbitrary subframes in a radio frame.

  The present invention has been made in view of the above points, and is suitable for performing uplink transmission power control for each subframe set obtained by grouping arbitrary subframes in a radio frame, a radio communication system, and transmission power. An object is to provide a control method.

  A user terminal according to the present invention is a user terminal that transmits an uplink signal, and a reception unit that receives configuration information of at least one subframe set configured by grouping subframes in a radio frame from a radio base station; A control unit for controlling the transmission power of the uplink signal for each subframe set based on a control parameter, and when the subframe set is changed based on the configuration information, the control unit The control parameter is reset.

  According to the present invention, uplink transmission power control can be appropriately performed for each subframe set obtained by grouping arbitrary subframes in a radio frame.

It is explanatory drawing of an example of a UL-DL structure. It is explanatory drawing of an example of dynamic TDD. It is explanatory drawing of the interference between base stations in the case of using different UL-DL structure between cells. It is explanatory drawing of an example of the uplink transmission power control for every sub-frame set. It is explanatory drawing of a sub-frame set. It is explanatory drawing of the transmission power of the uplink signal determined based on a control parameter. It is a conceptual diagram of the change of a sub-frame set. It is a figure which shows the reset example of the correction value in the user terminal which concerns on a 1st aspect. It is a figure which shows the reset example of the correction value in the user terminal which concerns on a 1st aspect. It is a figure which shows the reset example of the correction value in the user terminal which concerns on a 1st aspect. It is a figure which shows the reset example of the open loop control parameter in the user terminal which concerns on a 2nd aspect. It is a figure which shows the reset example of the open loop control parameter in the user terminal which concerns on a 2nd aspect. It is a figure which shows the reset example of the open loop control parameter in the user terminal which concerns on a 2nd aspect. It is a figure which shows the reset example of the open loop control parameter in the user terminal which concerns on a 2nd aspect. It is the schematic which shows an example of the radio | wireless communications system which concerns on this Embodiment. It is explanatory drawing of the whole structure of the wireless base station which concerns on this Embodiment. It is explanatory drawing of the whole structure of the user terminal which concerns on this Embodiment. It is explanatory drawing of the detailed structure of the wireless base station which concerns on this Embodiment. It is explanatory drawing of the detailed structure of the user terminal which concerns on this Embodiment.

  FIG. 2 is an explanatory diagram of an example of dynamic TDD. Note that the UL-DL configuration shown in FIGS. 1 and 2 is merely an example, and is not limited thereto. Dynamic TDD is switching the UL-DL configuration to dynamic. Specifically, in dynamic TDD, a UL-DL configuration notified semi-statically from a radio base station is dynamically changed to a different UL-DL configuration.

  FIG. 2 shows a case where the UL-DL configuration notified by SIB (System Information Block) 1 is dynamically changed. In dynamic TDD, it is not allowed to change the downlink subframe and the special subframe of the UL-DL configuration (UL-DL configuration 0 in FIG. 2) notified by the SIB1 to the uplink subframe.

  In FIG. 2, downlink subframes (subframe numbers 0 and 5) and special subframes (subframe number 6) in UL / DL configuration 0 are also downlink subframes or special subframes in other UL-DL configurations 1-6. It is a frame. For this reason, UL-DL configuration 0 notified by SIB1 can be dynamically changed to any of UL-DL configurations 1-6. On the other hand, although not shown, when UL-DL configuration 1 is notified by SIB1, dynamic change to any of UL-DL configurations 2, 4, and 5 is possible, but UL-DL configurations 0, 3 , 6 cannot be changed dynamically.

  A special subframe is a subframe for switching between a downlink subframe and an uplink subframe, and includes a downlink OFDM symbol, an uplink OFDM symbol, and a guard interval. When the number of downlink OFDM symbols is relatively large, the special subframe can also be regarded as a downlink subframe.

  In the dynamic TDD, as shown in FIG. 2, a fixed subframe (Fixed Subframe) and a flexible subframe (Flexible Subframe) can be provided. A fixed subframe is a subframe with the same transmission direction between UL-DL configurations. The flexible subframe is a subframe in which subframes having different transmission directions are different between UL-DL configurations.

  In FIG. 2, the special subframe is regarded as the downlink subframe and the fixed subframe and the flexible subframe are separated, but the present invention is not limited to this. When the special subframe is not regarded as a downlink subframe, the subframe 6 may be treated as a flexible subframe. It is also possible to signal the fixed subframe and the flexible subframe from the radio base station (eNB: eNodeB) by an upper layer including RRC or broadcast.

  In dynamic TDD, it is assumed that different UL-DL configurations are used between adjacent cells. FIG. 3 is an explanatory diagram of interference between base stations when different UL-DL configurations are used between adjacent cells. In FIG. 3, UL-DL configuration 4 is used in cell 1 formed by radio base station (eNB: eNodeB) 1, and UL-DL configuration 3 is used in cell 2 formed by radio base station 2.

  3, in subframe 4, the radio base station 1 transmits a downlink signal to a user terminal (UE: User Equipment) 1 in the cell 1, and the user terminal 2 in the cell 2 An uplink signal is transmitted to. In general, the transmission power of the downlink signal is larger than the transmission power of the uplink signal. For this reason, in the subframe 4, the downlink signal from the radio base station 1 gives large interference to the radio base station 2.

  Thus, when different UL-DL configurations are used between adjacent cells, inter-base station interference is assumed to occur in flexible subframes having different transmission directions between cells. For this reason, subframes (flexible subframes) having different transmission directions between cells and subframes (fixed subframes) having the same transmission direction are grouped to form subgroups (hereinafter referred to as subframe sets). It is considered to apply different uplink transmission power control for each.

  FIG. 4 is an explanatory diagram of an example of uplink transmission power control for each subframe set. In FIG. 4, as shown in FIG. 3, the UL-DL configuration 4 is used in the cell 1, and the UL-DL configuration 3 is used in the cell 2.

  In this case, the first subframe set is composed of subframes 2 and 3 (fixed subframes) having the same transmission direction (uplink) in cells 1 and 2 (FIG. 4A), and the second subframe set is cell 1. 4 is composed of subframe 4 (flexible subframe) in which the downlink signal is transmitted and the uplink signal is transmitted in cell 2 (FIG. 4B). As will be described later, the configuration of the subframe set is not limited to that shown in FIGS. 4A and 4B.

  In the first subframe set shown in FIG. 4A, uplink signals are transmitted in both cells 1 and 2, so the influence of inter-base station interference in the radio base station 2 is small. For this reason, in the first subframe set, the user terminal 2 transmits an uplink signal to the radio base station 2 with relatively small transmission power.

  On the other hand, in the second subframe set shown in FIG. 4B, since the downlink signal is transmitted in the cell 1, the influence of inter-base station interference in the radio base station 2 is large. For this reason, in the second subframe set, the user terminal 2 transmits an uplink signal to the radio base station 2 with a larger transmission power than in the first subframe set. Thereby, the reception quality (for example, SINR: Signal-to-Interference-plus-Noise Ratio) of the uplink signal in the radio base station 2 can be maintained.

  In FIG. 4, the first subframe set is composed of fixed subframes, and the second subframe set is composed of flexible subframes. However, the present invention is not limited to this. A subframe set may include any subframe within a radio frame. Also, the subframe set may be configured to include any subframe excluding a specific subframe (for example, a downlink fixed subframe) in the radio frame.

  FIG. 5 is an explanatory diagram of an example of a subframe set. In FIG. 5, the subframe set is configured to include arbitrary subframes 0-9 excluding downlink fixed subframes (subframes 0 and 5). In this case, the first subframe set (Subframe set # 1) includes subframes 1, 2, 3, 6, 7, and 8, and the second subframe set (Subframe set # 2) includes subframes. 4 and 9 may be included (Example 1). Alternatively, the first subframe set includes subframes 1, 2, 3, 4, 6, 7, 8, and 9, and the second subframe set may not include any subframe (eg, 2).

  Although not shown, the first and second subframe sets may be configured to include overlapping subframes. In addition, the first subframe set may be configured to include all or a part of the subframes constituting the second subframe set (that is, including the second subframe set). Further, the number of subframe sets is not limited to two. For example, in Example 2 illustrated in FIG. 5, the number of subframe sets may be regarded as 1. Three or more subframe sets may be provided.

  By the way, uplink transmission power control is performed using both open-loop control and closed-loop control. The open loop control is a control for satisfying a target received power according to a propagation loss (path loss) between the user terminal and the radio base station. This is performed based on statically notified parameters. The parameter is notified by higher layer signaling such as RRC (Radio Resource Control) signaling.

  On the other hand, closed-loop control is control for correcting a transmission power error, and is performed based on a transmission power control (TPC) command dynamically notified from a radio base station. The TPC command is included in, for example, downlink control information (DCI) transmitted by a downlink control channel (PDCCH: Physical Downlink Control Channel or EPDCCH: Enhanced Physical Downlink Control Channel).

FIG. 6 is an explanatory diagram of an example of uplink transmission power control using open loop control and closed loop control. FIG. 6A shows a calculation formula for transmission power of an uplink shared channel (PUSCH). As illustrated in FIG. 6A, PUSCH transmission power P _PUSCH (i) is calculated by, for example, Expression (1). In Expression (1), i is an index indicating a subframe. j is an index indicating the scheduling type. _PCMAX is the maximum allowable transmission power of the user terminal.

As shown in Expression (1), the open-loop control of the transmission power of _PUSCH is performed based on M _PUSCH (i), P _{O_PUSCH} (j), α, PL, Δ _TF (i). Here, M _PUSCH (i) is a bandwidth allocated for PUSCH. _{PO_PUSCH} (j) is a transmission power offset for satisfying the target reception power in the radio base station. PL is a propagation loss calculated by the user terminal based on received power of a downlink reference signal (for example, RSRP: Reference Signal Received Power). α is a coefficient set according to the propagation loss. Δ _TF (i) is an offset depending on MCS (Modulation and Coding Scheme).

  Also, closed loop control of PUSCH transmission power is performed based on f (i). f (i) is a correction value based on the TPC command. The correction value f (i) may be an accumulated value (accumulation value) obtained by accumulating the increase / decrease value of the transmission power indicated by the TPC command, or the transmission power increase / decrease value itself (absolute value) indicated by the TPC command. Also good.

式（３）において、δ_{ＰＵＳＣＨ}（ｉ−Ｋ_{ＰＵＳＣＨ}）は、サブフレーム（ｉ−Ｋ_{ＰＵＳＣＨ}）のＤＣＩに含まれるＴＰＣコマンドが示す送信電力の増減値（累積される値）である。式（３）では、サブフレームｉにおける補正値ｆ（ｉ）が、サブフレーム（ｉ−１）における補正値ｆ（ｉ−１）と上記ＴＰＣコマンドが示す増減値δ_{ＰＵＳＣＨ}（ｉ−Ｋ_{ＰＵＳＣＨ}）とに基づいて算出される。 Here, when the correction value f (i) is an accumulation value (accumulation mode), f (i) is given by the following equation (3), for example.

In Expression (3), δ _PUSCH (i−K _PUSCH ) is a transmission power increase / decrease value (accumulated value) indicated by the TPC command included in the DCI of the subframe (i−K _PUSCH ). In Expression (3), the correction value f (i) in the subframe i is changed from the correction value f (i−1) in the subframe (i−1) and the increase / decrease value δ _PUSCH (i−K _PUSCH ) indicated by the TPC command _. Based on the above.

式（４）において、δ_{ＰＵＳＣＨ}（ｉ−Ｋ_{ＰＵＳＣＨ}）は、サブフレーム（ｉ−Ｋ_{ＰＵＳＣＨ}）のＤＣＩに含まれるＴＰＣコマンドが示す送信電力の増減値である。このように、非累積モードにおいては、式（３）とは異なり、ｆ（ｉ−１）は考慮されない。 On the other hand, when the correction value f (i) is the increase / decrease value of the transmission power indicated by the TPC command (non-cumulative mode), f (i) is given by, for example, the following equation (4).

In Expression (4), δ _PUSCH (i−K _PUSCH ) is a transmission power increase / decrease value indicated by the TPC command included in the DCI of the subframe (i−K _PUSCH ). As described above, in the non-cumulative mode, f (i−1) is not taken into consideration, unlike the formula (3).

FIG. 6B shows a calculation formula for the transmission power of a sounding reference signal (SRS). SRS is a reference signal transmitted from a user terminal in order to estimate uplink channel quality in a radio base station. As illustrated in FIG. 6B, the transmission power P _SRS (i) of the _SRS is calculated by, for example, Expression (2).

As shown in the equation (2), the open loop control of the transmission power of the SRS includes the transmission power offset _{PO_PUSCH} (j), the coefficient α, the propagation loss PL, and the P _{SRS_OFFSET} and M _SRS used for calculating the transmission power of the PUSCH. Based on the above. Here, P _{SRS_OFFSET} is a transmission power offset for SRS notified by higher layer signaling such as RRC signaling. M _SRS is the bandwidth allocated for SRS. Further, the closed loop control of the transmission power of SRS is performed based on the correction value f (i), similarly to PUSCH.

FIG. 6C shows a calculation formula for transmission power of the uplink control channel (PUCCH). As illustrated in FIG. 6C, the transmission power P _PUCCH (i) of _PUCCH is calculated by, for example, Expression (5).

As shown in Expression (5), the open loop control of the transmission power of PUCCH is performed based on P _{O_PUCCH} , PL, h (n _CQI , n _HARQ ), and Δ _{F_PUCCH} (F). Here, _{PO_PUCCH} is a transmission power offset for satisfying the target reception power in the radio base station. PL is a propagation loss calculated by the user terminal based on the received power (for example, RSRP) of the downlink reference signal. h (n _CQI , n _HARQ ) is a value depending on the PUCCH format. Δ _{F_PUCCH} (F) corresponds to the PUCCH format and is a value notified in an upper layer.

  Moreover, the closed loop control of the transmission power of PUCCH is performed based on g (i). g (i) is a correction value based on the TPC command. The correction value g (i) may be a cumulative value obtained by accumulating the increase / decrease value of the transmission power indicated by the TPC command, or may be the increase / decrease value of the transmission power indicated by the TPC command itself.

In addition, Formula (1) (2) (5) shown in FIG. 6 and said Formula (3) (4) are only illustrations, and are not restricted to this. For example, various parameters shown in equations (1) to (5) may be provided for each component carrier (cell). Also, _{P O_PUCCH} of formula (1) (2) _{P O - PUSCH} in (j), Formula (5) are collectively may be referred to as a transmission power offset P0. Also, f (i) in equations (1) and (2) and g (i) in equation (5) may be collectively referred to as a correction value f.

  When uplink transmission power control as described above is performed independently for each subframe set, it is assumed that the subframe set is changed. Specifically, it is assumed that the subframes constituting the subframe set are changed or the number of subframe sets is changed. However, when a subframe set is changed, there is a possibility that control parameters used for uplink transmission power control for each changed subframe set cannot be reset appropriately.

  Therefore, when performing uplink transmission power control independently for each subframe set, the present inventors control used for uplink transmission power control for each changed subframe set even if the subframe set is changed. The present inventors have studied a transmission power control method capable of appropriately resetting parameters and have arrived at the present invention.

  In the transmission power control method of the present invention, the radio base station transmits configuration information of at least one subframe set (hereinafter referred to as subframe set configuration information) to the user terminal. The user terminal receives subframe set configuration information from the radio base station. The user terminal controls the transmission power of the uplink signal for each subframe set based on the control parameter. Moreover, a user terminal resets a control parameter, when a sub-frame set is changed based on sub-frame set structure information.

  Here, the subframe set is configured by grouping arbitrary subframes in a radio frame. Uplink transmission power control is applied independently for each subframe set. For this reason, the subframe set can also be called a transmission power control (TPC) subframe set or the like, which can be regarded as a collection of subframes to which the same uplink transmission power control is applied.

  As described above, the subframe set includes a subframe set including fixed subframes and a subframe set including flexible subframes, but is not limited thereto. The subframe set may include any subframe in the radio frame or may not include a subframe (see Example 2 in FIG. 5).

  Further, the subframe set may be configured to include any subframe excluding a specific subframe (for example, a downlink fixed subframe or a downlink subframe) in the radio frame (see FIG. 5). The number of subframe sets is, for example, 2, but is not limited thereto, and may be 1 (see Example 2 in FIG. 5) or 3 or more. A subframe extending over a plurality of frames may be defined as a subframe set.

  Further, the change of the subframe set may be a change of a subframe constituting the subframe set, a change of the number of subframe sets, or both. Further, the change of the subframe may be a case where a subframe set is set, or may be limited to a case where a subframe set different from the currently applied subframe set is set. When the subframe set is set, the control parameter may be newly set instead of resetting.

  Further, the uplink signal may be PUSCH, SRS, or an uplink control channel (PUCCH: Physical Uplink Control Channel).

  Further, the control parameter may be a correction value f for closed-loop control (for example, a correction value f (i) of equations (1) and (2) or a correction value g (i) of equation (5)) ( The first mode) may be a parameter for open-loop control (hereinafter, open-loop control parameter) (second mode), or both (a combination of the first and second modes).

Also, open loop control parameters, transmission of the uplink signal power offset P0 (e.g., _{P O_PUCCH} of formula (1) _(P in 2) _{O - PUSCH} (j) and equation (5)), the coefficient alpha (e.g., the equation (1 )), _And at least one of transmission power offsets for SRS (for example, P _{SRS_OFFSET in} Expression (2)).

  Hereinafter, the transmission power control method of the present invention will be described in detail. In the following, as shown in FIG. 7, the number of subframe sets is 2, the first subframe set (subframe set # 1) is composed of subframe 2 (fixed subframe), and the second subframe set Although the case where (subframe set # 2) is configured by subframes 3, 7, and 8 (flexible subframes) will be described, the configuration of the subframe set is not limited to this as described above.

  In the following, as shown in FIG. 7, the subframe set configuration information is notified to the user terminal in subframe 4 by higher layer signaling such as RRC signaling, and the subframe set configuration information is based on the subframe set configuration information. However, the present invention is not limited to this. The subframe set configuration information may be notified to the user terminal by broadcast information such as SIB, MAC (Medium Access Control) signaling, a downlink control channel (PDCCH or EPDCCH), and the like.

(First aspect)
The transmission power control method according to the first aspect will be described with reference to FIGS. Specifically, an example of resetting the correction value f for closed-loop control when the subframe set is changed based on the subframe set configuration information will be described with reference to FIGS. An example of resetting the correction value f for closed-loop control when the open-loop control parameter is changed will be described with reference to FIG. Here, the change of the subframe may be a case where a subframe set is set, or may be limited to a case where a subframe set different from the currently applied subframe set is set. In the following, the correction value for closed-loop control is expressed as a correction value f, but is not limited thereto, and may be expressed as a correction value g (including correction values g_1 and g_2).

  FIG. 8 is a diagram illustrating an example of resetting the correction value f when the subframes constituting the subframe set are changed. In FIG. 8, f_1 indicates the correction value f of the first subframe set, and f_2 indicates the correction value f of the second subframe set.

  In the following, the initial value of the correction value f is assumed to be “0”, but the initial value may not be “0”. “Resetting the correction value f to the initial value” may be simply referred to as “resetting the correction value f”. “Resetting the correction value f to the current value” is synonymous with “keeping the correction value f” and “maintaining the correction value f”.

  The “current value” is a correction value f used for closed-loop control of the latest subframe belonging to each subframe set. For example, as shown in FIG. 7, when the subframe set is changed in subframe 4, the current value of the first subframe set is the value of subframe 2, and the current value of the second subframe set is the subframe. A value of 3.

  As illustrated in FIG. 8A, when the subframe set is changed based on the subframe set configuration information, the user terminal may reset the correction value f of each subframe set to an initial value. For example, in FIG. 8A, when the subframe set is changed, the user terminal sets the correction value f_1 of the first subframe set and the correction value f_2 of the second subframe set to initial values “0”, respectively.

  As shown in the above equation (3), when the correction value f is a cumulative value obtained by accumulating the increase / decrease value of the transmission power indicated by the TPC command, the recognition of the correction value f is not recognized between the radio base station and the user terminal. It is assumed that it will not do. When the transmission power of the user terminal is the upper limit value, the user terminal does not accumulate the increase / decrease value indicated by the received TPC command, but the radio base station cannot recognize this. Further, when the user terminal cannot receive DCI including the TPC command, the user terminal does not accumulate the increase / decrease value indicated by the TPC command, but the radio base station cannot recognize this.

  In the case shown in FIG. 8A, the correction value f between the radio base station and the user terminal as described above is triggered by the change of the subframe set by resetting the correction value f of each subframe set to the initial value. Can be resolved.

  Also, as shown in FIG. 8B, when the subframe set is changed based on the subframe set configuration information, the user terminal inherits the correction value f of the specific subframe set (reset to the current value), The correction value f of another subframe set may be reset to the initial value. For example, in FIG. 8B, when the subframe set is changed, the user terminal inherits the correction value f_1 of the first subframe set (reset to the current value f_1) and sets the correction value f_2 of the second subframe set. Reset to the initial value “0”.

  In the case illustrated in FIG. 8B, the interference value is inherited (maintained) by inheriting (maintaining) the correction value f of a specific subframe set (for example, the first subframe set including fixed subframes) estimated to have a small variation in interference level. Only the correction value f of another subframe set (for example, the second subframe set composed of flexible subframes) estimated to have a large level fluctuation can be reset to the initial value. For this reason, when the correction value f is reset to the initial value in a specific subframe set that is estimated to have little fluctuation in interference level, unnecessary boost occurs and transmission power is reduced unnecessarily. Can be avoided.

  Also, as shown in FIG. 8C, when the subframe set is changed based on the subframe set configuration information, the user terminal inherits the correction value f of the specific subframe set (reset to the current value), The correction value f of another subframe set may be reset to the current value of a specific subframe set. For example, in FIG. 8C, when the subframe set is changed, the user terminal inherits the correction value f_1 of the first subframe set (reset to the current value) and sets the correction value f_2 of the second subframe set to the first value. Reset the correction value to f_1 for one subframe set.

  In the case shown in FIG. 8C, the correction value f of another subframe set is matched with the correction value f of a specific subframe set (for example, a first subframe set composed of fixed subframes) estimated to have low interference. Thus, it is possible to avoid unnecessary boosting by resetting the correction value f of the other subframe set to the initial value.

  Also, as shown in FIG. 8D, when the subframe set is changed based on the subframe set configuration information, the user terminal can change each subframe set based on the number of subframes a not changed in a specific subframe set. The correction value f of the subframe set may be reset by linear interpolation. For example, in FIG. 8D, it is assumed that the subframes of the ratio a are maintained (not changed) before and after the change of the first subframe set. In this case, the user terminal may reset the correction value f_1 of the first subframe set to “a * f_1 + (1−a) * f_2”. Further, the user terminal may reset the correction value f_2 of the second subframe set to “(1−a) * f_1 + a * f_2”.

  In the case shown in FIG. 8D, the correction value f of each subframe set is reset by linear interpolation based on the number of subframes that have not been changed within a specific subframe set, so that the subframe set is changed. In this case, the accuracy of the correction value f can be maintained as much as possible.

  Also, as shown in FIG. 8E, when the subframe set is changed based on the subframe set configuration information, the user terminal may inherit (reset to the current value) the correction value f of each subframe set. Good. For example, in FIG. 8E, the user terminal inherits the correction value f_1 of the first subframe set and the correction value f_2 of the second subframe set, respectively (reset to the current values f_1 and f_2, respectively).

  In the case shown in FIG. 8E, by inheriting the correction value f of each subframe set (reset to the current value), when the change of the subframe set is relatively small, the correction value f can be set semi-optimally. it can.

  FIG. 9 is a diagram illustrating an example of resetting the correction value f when the number of subframe sets is changed. In FIG. 9, f_1 indicates the correction value f of the first subframe set, and f_2 indicates the correction value f of the second subframe set.

  As illustrated in FIG. 9A, when the number of subframe sets increases based on the subframe set configuration information, the user terminal sets the increased correction value f of the subframe set to the correction value f_1 of the first subframe set. May be. For example, as illustrated in FIG. 9A, when the second subframe set is provided in addition to the first subframe set, the user terminal sets the correction value of the second subframe set to the correction value f_1 of the first subframe set. Set to. In FIG. 9A, the correction values of the first and second subframe sets may be reset to the initial value “0”.

  Also, as shown in FIG. 9B, when the number of subframe sets decreases based on the subframe set configuration information, the user terminal uses the remaining subframe set correction value f as the first subframe set correction value f_1. May be set. For example, as illustrated in FIG. 9B, when the second subframe set is deleted, the user terminal inherits (resets to the current value) the correction value f_1 of the remaining first subframe set. In FIG. 9B, the correction value f_1 of the first subframe set may be reset to the initial value “0”.

  Although not shown, when the number of subframe sets increases or decreases based on the subframe set configuration information, the user terminal is notified of the correction value f of the increased or left subframe set from the radio base station. You may reset to the correction value f of a sub-frame set. The notification may be performed by higher layer signaling such as RRC signaling, or may be performed using broadcast information or a downlink control channel (PDCCH or EPDCCH).

  As described above, when the subframe set is changed based on the subframe set configuration information, the user terminal can reset the correction value of each subframe set. Note that which operation the user terminal applies with reference to FIGS. 8 and 9 may be defined in advance in the user terminal, upper layer signaling such as RRC signaling, broadcast information, and downlink control. You may be notified to a user terminal by a channel (PDCCH or EPDCCH).

FIG. 10 is a diagram illustrating an example of resetting the correction value f when the open loop control parameter is changed. Incidentally, the open loop control parameter (Open loop PC parameter), as described above, _P of the transmission of the uplink signal power offset P0 (e.g., formula (1) _(P in 2) _{O_PUSCH} (j) and equation (5) _{O_PUCCH} ), A coefficient α (for example, the above equation (1)), and a transmission power offset for SRS (for example, P _{SRS_OFFSET in the} equation (2)).

  As illustrated in FIG. 10A, when the open loop control parameter is changed, the user terminal may reset the correction value f of each subframe set to an initial value. For example, in FIG. 10A, when the open loop control parameter is changed, the user terminal resets the correction value f_1 of the first subframe set and the correction value f_2 of the second subframe set to the initial value “0”, respectively. .

  Also, as shown in FIG. 10B, when the open loop control parameter is changed, the user terminal inherits the correction value f of a specific subframe set (reset to the current value) and corrects other subframe sets. The value f may be reset to the current value of a particular subframe set. For example, in FIG. 10B, when the open loop control parameter is changed, the user terminal inherits the correction value f_1 of the first subframe set (reset to the current value) and sets the correction value f_2 of the second subframe set. The correction value f_1 of the first subframe set is reset.

  Also, as shown in FIG. 10C, when the open loop control parameter is changed, the user terminal may inherit (reset to the current value) the correction value f of each subframe set. For example, in FIG. 10C, when the open loop control parameter is changed, the user terminal inherits the correction value f_1 of the first subframe set and the correction value f_2 of the second subframe set, respectively (current values f_1 and f_2, respectively). Reset).

  As described above, when the open loop control parameter is changed, the user terminal can reset the correction value of each subframe set. Note that which operation the user terminal applies with reference to FIG. 10 may be defined in advance in the user terminal, or higher layer signaling such as RRC signaling, broadcast information, or a downlink control channel ( The user terminal may be notified by PDCCH or EPDCCH.

  When the subframe set is changed based on the subframe set configuration information (FIGS. 8 and 9) and when the open loop control parameter of each subframe set is changed (FIG. 10), the user terminal The operation in the latter case may be applied with priority. Note that giving priority to the latter operation may be defined in advance in the user terminal, or may be notified to the user terminal by higher layer signaling such as RRC signaling, broadcast information, or a downlink control channel (PDCCH or EPDCCH). Good.

(Second aspect)
With reference to FIGS. 11-14, the transmission power control method which concerns on a 2nd aspect is demonstrated. An example of resetting the open loop control parameter when the subframe set is changed based on the subframe set configuration information will be described. Specifically, an example of resetting the open loop control parameter when the subframe set is changed and the open loop control parameter is not signaled will be described with reference to FIGS. An example of resetting the open loop control parameter when the open loop control parameter is signaled when the subframe set is changed will be described with reference to FIG. Here, the change of the subframe may be a case where a subframe set is set, or may be limited to a case where a subframe set different from the currently applied subframe set is set.

In addition, in FIG. 11-14, the case where the open loop control parameters are the transmission power offset P0 (for example, P _{O_PUSCH} (j) in Expression (1)) and the coefficient α (for example, Expression (1) above). Although explained, it is not limited to these. The open loop control parameter may also include a transmission power offset for SRS (eg, P _{SRS_OFFSET in} equation (2)). Further, the open loop control parameter may be only the transmission power offset P0 (for example, P _{O_PUCCH in} Expression (5)).

FIG. 11 is a diagram illustrating an example of resetting an open loop control parameter when a subframe configuring a subframe set is changed without signaling the open loop control parameter. In FIG. 11, P0_1 and P0_2 indicate transmission power offsets of the first subframe set and the second subframe set (for example, _{PO_PUSCH} (j) in equations (1) and (2)), respectively. Further, α_1 and α_2 represent coefficients α (for example, α in the equations (1) and (2)) of the first subframe set and the second subframe set, respectively.

  In the following, “resetting the open loop control parameter to the current value” is synonymous with “inheriting (keep) the open loop control parameter” and “maintaining the open loop control parameter”. . The “current value” is a value of an open loop control parameter used for transmission power control of the latest subframe belonging to each subframe set. For example, as shown in FIG. 7, when the subframe set is changed in subframe 4, the current value of the first subframe set is the value of subframe 2, and the current value of the second subframe set is the subframe. A value of 3.

  As shown in FIG. 11A, when the subframe set is changed based on the subframe set configuration information without signaling the open loop control parameter, the user terminal inherits the open loop control parameter of each subframe set (currently It may be reset to a value). For example, in FIG. 11A, the user terminal inherits (resets to the current value) the transmission power offset P0_1 and coefficient α_1 of the first subframe set. Also, the user terminal inherits (resets to the current value) the transmission power offset P0_2 and coefficient α_2 of the second subframe set.

  In the case shown in FIG. 11A, when the change of the subframe set is relatively small by inheriting (resetting to the current value) the open loop control parameter of each subframe set, the open loop control parameter (eg, transmission power offset) P0, coefficient α) can be set sub-optimally.

  Also, as shown in FIG. 11B, when the subframe set is changed based on the subframe set configuration information without signaling the open loop control parameter, the user terminal sets the open loop control parameter of the specific subframe set. It may be inherited (reset to the current value), and the open loop control parameters of other subframe sets may be reset to the current value of a specific subframe set. For example, in FIG. 11B, the user terminal inherits (resets to the current value) the transmission power offset P0_1 and coefficient α_1 of the first subframe set. Also, the user terminal resets the transmission power offset P0_2 and coefficient α_2 of the second subframe set to the transmission power offset P0_1 and coefficient α_1 of the first subframe set, respectively.

  In the case shown in FIG. 11B, the open-loop control parameter of another subframe set is added to the open-loop control parameter of a specific subframe set (for example, the first subframe set composed of fixed subframes) estimated to have low interference. By combining these, unnecessary boost is generated in the other subframe set and interference with adjacent cells can be avoided.

  By the way, the value of the open loop control parameter includes a value common to user terminals (cell_specific) in the cell (that is, a value common to all user terminals in the cell) (hereinafter referred to as UE common value), and a user terminal in the cell. An individual (UE_specific) value (hereinafter referred to as a UE individual value) may be notified. The UE common value and the UE individual value may be notified to the user terminal using higher layer signaling such as RRC signaling, or notified to the user terminal using broadcast information or a downlink control channel (PDCCH or EPDCCH). May be.

  When the subframe set is changed without signaling of the open loop control parameter, the open loop control parameter may be reset using either the UE common value or the UE individual value, or the UE common value and the UE individual value may be reconfigured. The open loop control parameter may be reset using both values.

  FIG. 12 is a diagram illustrating an example of resetting an open loop control parameter using a UE common value and / or a UE individual value. Although FIG. 12 illustrates a case in which the UE common values (P0_normal1, P0_normal2) and UE individual values (P0_1, P0_2) are notified of the transmission power offset P0, the present invention is not limited to this. Of course, the UE common value and the UE individual value may be notified of the coefficient α and the transmission power offset for SRS.

  As shown in FIG. 12A, when the subframe set is changed without signaling of the open loop control parameter, the user terminal may reset the open loop control parameter of each subframe set to a UE common value. For example, in FIG. 12A, the user terminal resets the transmission power offset of the first subframe set to the UE common value P0_normal1. Similarly, the user terminal resets the transmission power offset of the second subframe set to the UE common value P0_normal2. The coefficient α is the same as that shown in FIG.

  In the case shown in FIG. 12A, since the open loop control parameter is reset to the UE common value, an unnecessary transmission power offset occurs between user terminals, and interference with adjacent cells and lack of transmission power can be avoided.

  Also, as shown in FIG. 12B, when the subframe set is changed without signaling of the open loop control parameter, the user terminal inherits the open loop control parameter of each subframe set (UE common value and UE individual value). The current value, which is the total value of For example, in FIG. 12A, the user terminal resets the transmission power offset of the first subframe set to the total value of the UE common value P0_normal1 and the UE individual value P0_1. Similarly, the user terminal resets the transmission power offset of the second subframe set to the total value of the UE common value P0_normal2 and the UE individual value P0_2. The coefficient α is the same as that shown in FIG.

  In the case shown in FIG. 12B, by inheriting the open loop control parameter of each subframe set (reset to the current value that is the sum of the UE common value and the UE individual value), the change of the subframe set is relatively If small, the open loop control parameters can be set sub-optimally.

  FIG. 13 is a diagram illustrating an example of resetting the open loop control parameter when the number of subframe sets is changed. As illustrated in FIG. 13A, when the number of subframe sets increases without signaling of the open loop control parameter, the user terminal determines the increased open frame control parameter of the subframe set as the open loop control parameter of the first subframe set. You may set to the value of.

  For example, as shown in FIG. 13A, when the second subframe set is provided in addition to the first subframe set, the user terminal sets the transmission power offset of the second subframe set to the transmission power of the first subframe set. Set to offset P0_1. Also, the user terminal sets the coefficient α of the second subframe set to the coefficient α_1 of the first subframe set.

  Further, as shown in FIG. 13B, when the number of subframe sets decreases without signaling of the open loop control parameter, the user terminal sets the open loop control parameters of the remaining subframe set to the opening of the first subframe set. You may set to the value of a loop control parameter. For example, as illustrated in FIG. 13B, when the second subframe set is deleted, the user terminal inherits the transmission power control parameter P0_1 and the coefficient α_1 of the remaining first subframe set (reset to the current value). To do.

  As described above, when the subframe set is changed without signaling the open loop control parameter, the user terminal appropriately sets the value of the open loop control parameter of each subframe set without signaling the open loop control parameter. Can be reset to Note that which operation the user terminal applies with reference to FIGS. 11 to 13 may be defined in advance in the user terminal, upper layer signaling such as RRC signaling, broadcast information, and downlink control. You may be notified to a user terminal by a channel (PDCCH or EPDCCH).

  FIG. 14 is a diagram illustrating an example of resetting the open loop control parameter when the subframe set is changed together with the signaling of the open loop control parameter. In addition, although an open loop control parameter shall be notified to a user terminal by upper layer signaling, such as RRC signaling, you may notify a user terminal by alerting | reporting information or a downlink control channel (PDCCH or EPDCCH).

  As shown in FIG. 14, when the subframe set is changed together with the signaling of the open loop control parameter, the user terminal resets the open loop control parameter of each subframe set to the value of the signaled open loop control parameter. . For example, in FIG. 14, the user terminal resets the transmission power offset P0_1 and the coefficient α_1 of the first subframe set to the signaled P0_1 and α_1, respectively. Similarly, the user terminal resets the transmission power offset P0_2 and the coefficient α_2 of the second subframe set to the signaled P0_2 and α_2, respectively.

(Configuration of wireless communication system)
Hereinafter, the configuration of the wireless communication system according to the present embodiment will be described. In this wireless communication system, the transmission power control method according to the above-described first to second aspects is applied. In addition, the transmission power control method according to the first-second aspect may be applied in combination or may be applied alone.

  FIG. 15 is a schematic configuration diagram of a radio communication system according to the present embodiment. As shown in FIG. 15, the radio communication system 1 includes a macro base station 11 that forms a macro cell C1, and small base stations 12a and 12b that are arranged in the macro cell C1 and form a small cell C2 that is narrower than the macro cell C1. I have. The user terminal 20 is configured to be able to wirelessly communicate with at least one of the macro base station 11 and the small base stations 12a and 12b (hereinafter collectively referred to as the small base station 12). The numbers of macro base stations 11 and small base stations 12 are not limited to the numbers shown in FIG.

  In the macro cell C1 and the small cell C2, the same frequency band may be used, or different frequency bands may be used. Further, the macro base station 11 and each small base station 12 may be connected by a relatively high-speed line (ideal backhaul) such as an optical fiber, or a relatively low-speed line (non-ideal backhaul) such as an X2 interface. ) May be connected.

  When connected via a high-speed line, intra-base station carrier aggregation (such as intra-eNB CA) that integrates at least one CC of the macro base station 11 and at least one CC of the small base station 12 may be performed. When connected by a low-speed line, inter-base station carrier aggregation (inter-eNB CA, Inter-site CA, etc.) is performed between at least one CC of the macro base station 11 and at least one CC of the small base station 12. It may be done. CC may be called a cell, a frequency band, or the like.

  In addition, the macro base station 11 and each small base station 12 are connected to the upper station apparatus 30 and connected to the core network 40 via the upper station apparatus 30. The upper station device 30 includes, for example, an access gateway device, a radio network controller (RNC), a mobility management entity (MME), and the like, but is not limited thereto.

  The macro base station 11 is a radio base station having a relatively wide coverage, and may be referred to as an eNodeB (eNB), a radio base station, a transmission point, or the like. The small base station 12 is a radio base station having local coverage, and may be called an RRH (Remote Radio Head), a pico base station, a femto base station, a Home eNodeB, a transmission point, an eNodeB (eNB), or the like. . The user terminal 20 is a terminal that supports various communication schemes such as LTE and LTE-A, and may include not only a mobile communication terminal but also a fixed communication terminal.

  In the wireless communication system 1, a frequency division duplex (FDD) or / and a time division duplex (TDD) scheme is applied as a duplex scheme. Further, when the TDD scheme is applied, a UL-DL configuration (for example, FIG. 1) indicating a configuration (ratio) between an uplink subframe and a downlink subframe in a radio frame is used.

  Further, in the wireless communication system 1, OFDMA (Orthogonal Frequency Division Multiple Access) is applied to the downlink and SC-FDMA (Single Carrier Frequency Division Multiple Access) is applied to the uplink as the radio access scheme.

  Further, in the wireless communication system 1, as a downlink communication channel, a downlink shared channel (PDSCH: Physical Downlink Shared Channel) shared by each user terminal 20 and a downlink control channel (PDCCH: Physical Downlink Control Channel, EPDCCH: Enhanced) Physical Downlink Control Channel), PCFICH, PHICH, broadcast channel (PBCH), etc. are used. User data and higher layer control information are transmitted by the PDSCH. Downlink control information (DCI) is transmitted by PDCCH and EPDCCH. Note that EPDCCH is frequency division multiplexed with PDSCH.

  In the radio communication system 1, an uplink shared channel (PUSCH) shared by each user terminal 20 and an uplink control channel (PUCCH) are used as uplink communication channels. It is done. User data and higher layer control information are transmitted by PUSCH. Also, downlink radio quality information (CQI: Channel Quality Indicator), delivery confirmation information (ACK / NACK), and the like are transmitted by PUCCH. In the wireless communication system 1, a sounding reference signal (SRS) or the like is used as an uplink reference signal.

  Hereinafter, when the macro base station 11 and the small base station 12 are not distinguished, they are collectively referred to as a radio base station 10. With reference to FIG. 16 and 17, the whole structure of the radio base station 10 and the user terminal 20 which concerns on this Embodiment is demonstrated.

  FIG. 16 is an overall configuration diagram of the radio base station 10 according to the present embodiment. The radio base station 10 includes a plurality of transmission / reception antennas 101 for MIMO transmission, an amplifier unit 102, a transmission / reception unit 103 (transmission unit, reception unit), a baseband signal processing unit 104, a call processing unit 105, a transmission And a road interface 106.

  User data transmitted from the radio base station 10 to the user terminal 20 via the downlink is input from the higher station apparatus 30 to the baseband signal processing unit 104 via the transmission path interface 106.

  The baseband signal processing unit 104 performs PDCP layer processing, user data division / combination, RLC layer transmission processing such as RLC (Radio Link Control) retransmission control transmission processing, MAC (Medium Access Control) retransmission control, for example, HARQ transmission processing, scheduling, transmission format selection, channel coding, inverse fast Fourier transform (IFFT) processing, and precoding processing are performed and transferred to each transceiver 103. The downlink control signal is also subjected to transmission processing such as channel coding and inverse fast Fourier transform, and is transferred to each transmitting / receiving unit 103.

  Each transmitting / receiving unit 103 converts the downlink signal output by precoding for each antenna from the baseband signal processing unit 104 to a radio frequency band. The amplifier unit 102 amplifies the frequency-converted radio frequency signal and transmits the amplified signal using the transmission / reception antenna 101.

  On the other hand, for the uplink signal, the radio frequency signal received by each transmitting / receiving antenna 101 is amplified by the amplifier unit 102, frequency-converted by each transmitting / receiving unit 103, converted into a baseband signal, and sent to the baseband signal processing unit 104. Entered.

  The baseband signal processing unit 104 performs FFT processing, IDFT processing, error correction decoding, MAC retransmission control reception processing, RLC layer, and PDCP layer reception processing on user data included in the input uplink signal. The data is transferred to the higher station apparatus 30 via the transmission path interface 106. The call processing unit 105 performs call processing such as communication channel setting and release, status management of the radio base station 10, and radio resource management.

  FIG. 17 is an overall configuration diagram of the user terminal 20 according to the present embodiment. The user terminal 20 includes a plurality of transmission / reception antennas 201 for MIMO transmission, an amplifier unit 202, a transmission / reception unit 203 (transmission unit, reception unit), a baseband signal processing unit 204, and an application unit 205. . Note that the user terminal 20 may switch the reception frequency by one reception circuit (RF circuit) or may have a plurality of reception circuits.

  As for the downlink signal, radio frequency signals received by the plurality of transmission / reception antennas 201 are amplified by the amplifier unit 202, frequency-converted by the transmission / reception unit 203, and input to the baseband signal processing unit 204. The baseband signal processing unit 204 performs FFT processing, error correction decoding, reception processing for retransmission control, and the like. User data included in the downlink signal is transferred to the application unit 205. The application unit 205 performs processing related to layers higher than the physical layer and the MAC layer. Also, broadcast information in the downlink data is also transferred to the application unit 205.

  On the other hand, uplink user data is input from the application unit 205 to the baseband signal processing unit 204. In the baseband signal processing unit 204, transmission processing for retransmission control (H-ARQ (Hybrid ARQ)), channel coding, precoding, DFT processing, IFFT processing, and the like are performed and transferred to each transmitting / receiving unit 203. The transmission / reception unit 203 converts the uplink signal (including PUSCH, SRS, PUCCH) output from the baseband signal processing unit 204 into a radio frequency. Thereafter, the amplifier unit 202 amplifies the frequency-converted radio frequency signal and transmits the amplified signal using the transmitting / receiving antenna 201.

  Next, detailed configurations of the radio base station 10 and the user terminal 20 will be described with reference to FIGS. The detailed configuration of the radio base station 10 illustrated in FIG. 18 is mainly configured by the baseband signal processing unit 104. Further, the detailed configuration of the user terminal 20 illustrated in FIG. 19 is mainly configured by the baseband signal processing unit 204.

  FIG. 18 is a detailed configuration diagram of radio base station 10 according to the present embodiment. As illustrated in FIG. 18, the radio base station 10 includes a measurement unit 301, a TPC command generation unit 302, an open loop control parameter generation unit 303, and a subframe set configuration information generation unit 304.

  The measurement unit 301 measures the reception quality (for example, RSRQ: Reference Signal Received Quality) of the uplink signal from the user terminal. The measurement unit 301 outputs the measurement result to the TPC command generation unit 302.

  The TPC command generation unit 302 generates a TPC command used for closed loop control based on the measurement result by the measurement unit 301. As described above, the TPC command indicates an increase / decrease value of the transmission power of the uplink signal. Further, the uplink signal may be PUSCH, SRS, or PUCCH.

  Specifically, the TPC command generation unit 302 generates a TPC command for each subframe set based on subframe set configuration information from a subframe set configuration information generation unit 304 described later. The TPC command is not limited to each subframe set, and may be common to all subframe sets.

  The generated TPC command is output to the transmission / reception unit 103 and transmitted to the user terminal 20 using the downlink control channel (PDCCH or EPDCCH). Further, in the accumulation mode, the TPC command generation unit 302 may accumulate the increase / decrease values indicated by the TPC command (see the above equation (3)) and generate the TPC command based on the accumulation value.

The open loop control parameter generation unit 303 generates an open loop control parameter used for the open loop control. As described above, the open loop control parameter is the transmission of the uplink signal power offset P0 _{(P O_PUCCH} of example, the formula (1) _(P in 2) _{O - PUSCH} (j) and equation (5)), the coefficient alpha (e.g., the Α in Expression (1) may be at least one of transmission power offsets for SRS (for example, P _{SRS_OFFSET in} Expression (2)).

  Specifically, the open loop control parameter generation unit 303 generates an open loop control parameter for each subframe set based on subframe set configuration information from a subframe set configuration information generation unit 304 described later.

  The generated open loop control parameter is output to the transmission / reception unit 103 and transmitted to the user terminal 20 using higher layer signaling such as RRC signaling. The open loop control parameter is not limited to higher layer signaling, and may be transmitted to the user terminal 20 using broadcast information or a downlink control channel (PDCCH or EPDCCH). Moreover, the value of the open loop control parameter may include the above-described UE common value and UE individual value.

  The subframe set configuration information generation unit 304 generates subframe set configuration information indicating the configuration of the subframe set. As described above, a subframe set is configured by grouping arbitrary subframes in a radio frame (for example, see FIG. 5), and serves as a unit for switching transmission power of an uplink signal. The subframe set may be configured by grouping fixed subframes and flexible subframes. The subframe set configuration information indicates at least one of the subframes constituting the subframe set and the number of subframe sets.

  The generated subframe set configuration information is output to the transmission / reception section 103 and transmitted to the user terminal 20 using higher layer signaling such as RRC signaling. The subframe set configuration information is not limited to higher layer signaling, and may be transmitted to the user terminal 20 using broadcast information or a downlink control channel (PDCCH or EPDCCH).

  FIG. 19 is a detailed configuration diagram of the user terminal 20 according to the present embodiment. As illustrated in FIG. 19, the user terminal 20 includes a transmission power control unit 401 (control unit), a TPC command acquisition unit 402, an open loop control parameter acquisition unit 403, a subframe set configuration information acquisition unit 404, and a resetting unit 405 ( Control section).

  The transmission power control unit 401 controls transmission power of uplink signals (PUSCH, SRS, PUCCH, etc.) for each subframe set based on the control parameter. As described above, the control parameter may be the correction value f for closed loop control (for example, the correction value f (i) of the equations (1) and (2) or the correction value g (i) of the equation (5)). It may be (first mode), an open loop control parameter (second mode), or both (combination of first and second modes).

  Specifically, the transmission power control unit 401 controls the transmission power of the uplink signal for each subframe set based on the correction value f determined based on the TPC command (closed loop control). The correction value f may be a cumulative value obtained by accumulating the increase / decrease value indicated by the TPC command (accumulation mode, for example, Equation (3)), or may be the increase / decrease value itself indicated by the TPC command (non-accumulation). Mode, eg, equation (4)).

Further, the transmission power control unit 401 controls the transmission power of the uplink signal for each subframe set based on the open loop control parameter (open loop control). As described above, the open loop control parameter is the transmission of the uplink signal power offset P0 _{(P O_PUCCH} of example, the formula (1) _(P in 2) _{O - PUSCH} (j) and equation (5)), the coefficient alpha (e.g., the Α in Expression (1) may be at least one of transmission power offsets for SRS (for example, P _{SRS_OFFSET in} Expression (2)).

  The TPC command acquisition unit 402 acquires the TPC command transmitted from the radio base station 10. Specifically, the transmission / reception unit 203 blind-decodes the downlink control channel (PDCCH or EPDCCH search space) and receives DCI. The TPC command acquisition unit 402 acquires the TPC command included in the DCI and outputs it to the transmission power control unit 401.

  The open loop control parameter acquisition unit 403 acquires the open loop control parameter transmitted from the radio base station 10. Specifically, the transmission / reception unit 203 receives an open loop control parameter transmitted by higher layer signaling such as RRC signaling. The open loop control parameter acquisition unit 403 acquires the open loop control parameter and outputs it to the transmission power control unit 401. Note that the transmission / reception unit 203 is not limited to higher layer signaling, and may acquire open loop control parameters transmitted by broadcast information or a downlink control channel (PDCCH or EPDCCH).

  The subframe set configuration information acquisition unit 404 acquires the subframe set configuration information transmitted from the radio base station 10. As described above, the subframe set configuration information indicates at least one of the subframes constituting the subframe set and the number of subframe sets.

  Specifically, the transmission / reception unit 203 receives subframe set configuration information transmitted by higher layer signaling such as RRC signaling. The subframe set configuration information acquisition unit 404 acquires the subframe set configuration information and outputs it to the resetting unit 405. In addition, the transmission / reception part 203 is not restricted to higher layer signaling, You may receive the sub-frame set structure information transmitted by alerting | reporting information or a downlink control channel (PDCCH or EPDCCH).

  The resetting unit 405 resets the control parameter when the subframe set is changed based on the subframe set configuration information. As described above, the control parameter may be the correction value f for closed loop control (for example, the correction value f (i) of the equations (1) and (2) or the correction value g (i) of the equation (5)). It may be (first mode), an open loop control parameter (second mode), or both (combination of first and second modes). Further, the change of the subframe set may be a change of a subframe constituting the subframe set, a change of the number of subframe sets, or both. Further, the change of the subframe may be a case where a subframe set is set, or may be limited to a case where a subframe set different from the currently applied subframe set is set. When the subframe set is set, the resetting unit 405 may newly set instead of resetting the control parameter.

  Specifically, when the subframe set is changed based on the subframe set configuration information, the resetting unit 405 uses one of the methods described with reference to FIGS. 8A to 8E to determine each subframe set. The correction value f may be reset. Note that which method is used may be specified in advance, or may be notified using higher layer signaling such as RRC signaling, broadcast information, or a downlink control channel (PDCCH or EPDCCH).

  Further, when the number of subframe sets increases based on the subframe set configuration information, the resetting unit 405 sets the increased correction value f of the subframe set to the first subframe as described with reference to FIG. 9A. The set correction value f_1 may be set. Further, when the number of subframe sets decreases based on the subframe set configuration information, the resetting unit 405 sets the correction value f of the remaining subframe set to the first subframe set as described with reference to FIG. 9B. The frame set correction value f_1 may be set.

  In addition, when the open loop control parameter is changed, the resetting unit 405 may reset the correction value f of each subframe set using any of the methods described with reference to FIGS. 10A to 10C. . Note that which method is used may be specified in advance, or may be notified using higher layer signaling such as RRC signaling, broadcast information, or a downlink control channel (PDCCH or EPDCCH).

  Also, the resetting unit 405 is configured to change the user terminal when the subframe set is changed based on the subframe set configuration information (FIGS. 8 and 9) and when the open loop control parameter is changed (FIG. 10). May apply the operation in the latter case with priority. Note that giving priority to the latter operation may be defined in advance in the user terminal, or may be notified to the user terminal by higher layer signaling such as RRC signaling, broadcast information, or a downlink control channel (PDCCH or EPDCCH). Good.

  Also, the resetting unit 405 uses any of the methods described with reference to FIGS. 11A to 11B when the subframe set is changed based on the subframe set configuration information without signaling the open loop control parameter. Thus, the open loop control parameters of each subframe set may be reset. Note that which method is used may be specified in advance, or may be notified using higher layer signaling such as RRC signaling, broadcast information, or a downlink control channel (PDCCH or EPDCCH).

  Further, when the subframe set is changed based on the subframe set configuration information without signaling the open loop control parameter, the reconfiguration unit 405 may change the UE common value as described with reference to FIGS. 12A-12B. Alternatively, the open loop control parameter may be reset using either the UE individual value, or the open loop control parameter may be reset using both the UE common value and the UE individual value. Note that which method is used may be specified in advance, or may be notified using higher layer signaling such as RRC signaling, broadcast information, or a downlink control channel (PDCCH or EPDCCH).

  In addition, when the number of subframe sets increases without signaling the open loop control parameter, the resetting unit 405 sets the open loop control parameter of the increased subframe set to the first subframe set as described with reference to FIG. 13A. The open loop control parameter value may be set. In addition, when the number of subframe sets decreases without signaling the open loop control parameter, the resetting unit 405 sets the open loop control parameters of the remaining subframe sets to the first subframe as described with reference to FIG. 13B. It may be set to the value of the set open loop control parameter.

  Further, when the subframe set is changed together with the signaling of the open loop control parameter, the resetting unit 405, as shown in FIG. 14, sets the value of the open loop control parameter signaled as the open loop control parameter of each subframe set. You may reset it.

  According to radio communication system 1 according to the present embodiment, it is possible to appropriately perform uplink transmission power control for each subframe set. Specifically, when uplink transmission power control is performed independently for each subframe set, even if the subframe set is changed, the control parameter used for uplink transmission power control for each changed subframe set is appropriately set. Can be reset.

  Although the present invention has been described in detail using the above-described embodiments, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention. Moreover, each embodiment can be applied in combination as appropriate.

1 ... wireless communication system,
DESCRIPTION OF SYMBOLS 10 ... Wireless base station 20 ... User terminal 30 ... Host station apparatus 40 ... Core network 101 ... Transmission / reception antenna 102 ... Amplifier part 103 ... Transmission / reception part 104 ... Baseband signal processing part 105 ... Call processing part 106 ... Transmission path interface 201 ... Transmission / reception Antenna 202 ... Amplifier 203 ... Transmission / reception unit 204 ... Baseband signal processing unit 205 ... Application unit 301 ... Measurement unit 302 ... TPC command generation unit 303 ... Open loop control parameter generation unit 304 ... Subframe set configuration information generation unit 401 ... Transmission Power control unit 402 ... TPC command acquisition unit 403 ... open loop control parameter acquisition unit 404 ... subframe set configuration information acquisition unit 405 ... resetting unit

Claims (10)

A user terminal that transmits an uplink signal,
A receiving unit that receives configuration information of at least one subframe set configured by grouping subframes in a radio frame from a radio base station;
A control unit for controlling the transmission power of the uplink signal for each subframe set based on a control parameter,
The said control part resets the said control parameter, when the said sub-frame set is changed based on the said structure information, The user terminal characterized by the above-mentioned. The receiving unit receives a transmission power control (TPC) command used for closed loop control from the radio base station,
The user terminal according to claim 1, wherein the control parameter is a correction value determined based on the TPC command.   The user terminal according to claim 2, wherein when the subframe set is changed based on the configuration information, the control unit resets the correction value of each subframe set to an initial value.   When the subframe set is changed based on the configuration information, the control unit resets the correction value of a specific subframe set to a current value and sets the correction value of another subframe set to an initial value. The user terminal according to claim 2, wherein the user terminal is reset.   When the subframe set is changed based on the configuration information, the control unit resets the correction value of a specific subframe set to a current value, and determines the correction value of another subframe set. The user terminal according to claim 2, wherein the current value of the subframe set is reset to the current value.   When the subframe set is changed based on the configuration information, the control unit linearly interpolates the correction value of each subframe set based on the number of subframes not changed in a specific subframe set. The user terminal according to claim 2, wherein the user terminal is reset.   The user terminal according to claim 2, wherein the control unit resets the correction value of each subframe set to a current value when the subframe set is changed based on the configuration information. The control parameter is an open loop control parameter that is at least one of a transmission power offset used for open loop control, a coefficient multiplied by a propagation loss, and a transmission power offset for a sounding reference signal,
The user terminal according to claim 1, wherein the receiving unit receives the value of the open loop control parameter from the radio base station. A wireless communication system in which a user terminal transmits an uplink signal,
A radio base station includes a transmission unit that transmits configuration information of at least one subframe set configured by grouping subframes in a radio frame to the user terminal. The user terminal transmits the configuration information to the radio terminal. A receiving unit that receives from the base station, and a control unit that controls transmission power of the uplink signal for each subframe set based on a control parameter,
The wireless communication system, wherein the control unit resets the control parameter when the subframe set is changed based on the configuration information. An uplink signal transmission power control method comprising:
In the radio base station, transmitting the configuration information of at least one subframe set configured by grouping the subframes in the radio frame to the user terminal;
In the user terminal, a step of receiving the configuration information from the radio base station, a step of controlling transmission power of the uplink signal for each subframe set based on a control parameter, and the subframe based on the configuration information And a step of resetting the control parameter when the set is changed.

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