WO2018159794A1

WO2018159794A1 - Radio base station

Info

Publication number: WO2018159794A1
Application number: PCT/JP2018/007925
Authority: WO
Inventors: 貴之五十川; 尚人大久保; 耕平清嶋; 輝雄川村; 翔吉田
Original assignee: 株式会社Ｎｔｔドコモ
Priority date: 2017-03-03
Filing date: 2018-03-02
Publication date: 2018-09-07

Abstract

This radio base station is provided with: a receiving state acquisition unit (120) which acquires the interference level in multiple cells, including the local cell to which a user equipment is connected, and/or the received communication quality in the user equipment in the multiple cells; and a power control unit (140) which limits the transmission power if the interference level or the received communication quality in the multiple cells acquired by the receiving state acquisition unit (120) is within a prescribed range.

Description

Wireless base station

The present invention relates to a radio base station that controls transmission power of a user apparatus.

The 3rd Generation Partnership Project (3GPP) specifies LTE-Advanced (hereinafter referred to as LTE including LTE-Advanced) for the purpose of further speeding up Long Term Evolution (LTE). In 3GPP, specifications for LTE successor systems called 5G (5th generation mobile mobile communication systems) are also being considered.

In LTE, it is specified to control uplink transmission power based on a path loss between a radio base station (eNB) and a user apparatus (UE). Specifically, it is specified to control the transmission power of a physical uplink shared channel, specifically, PUSCH (Physical-Uplink-Shared-Channel) based on downlink path loss (for example, Non-Patent Document 1). reference).

Recently, there are UEs (hereinafter referred to as “specific UEs”) that perform communication in the sky with good visibility in all directions rather than on the ground, such as UEs installed in drones.

Such a specific UE has a good line of sight, so the downlink path loss is small. The specific UE is highly likely to perform communication at a position where a plurality of cells with a small path loss can be detected. That is, since the specific UE has a good line of sight, the signal level received from the specific UE by a non-existing cell in which the specific UE is not located may be very high.

In the current LTE specifications, communication over the air like a specific UE is not assumed. For this reason, when the path loss is small, a high target reception quality (specifically, Target SIR) is set for throughput improvement based on the assumption that the UE is located near the eNB. The UE is generally controlled to increase the transmission power of the PUSCH so as to satisfy the set high target reception quality.

However, when such control is executed in the specific UE, there is a possibility of interference with the own cell to which the specific UE is connected or a neighboring cell formed in the vicinity of the own cell. In other words, because the communication is performed in the sky, a specific UE having a good line-of-sight in all directions may cause interference to its own cell and neighboring cells as compared to a normal UE that performs communication on the ground or the like. high.

In particular, when a plurality of specific UEs are connected to different neighboring cells, the specific UEs continuously increase the transmission power until the target reception quality is satisfied, and thus there is a possibility of causing large interference with each other. Moreover, such a state gives interference also to other UEs connected to the cell.

Therefore, the present invention has been made in view of such a situation, and even when a user environment such as a user device mounted on a drone has a good outlook and a communication environment similar to a plurality of cells, An object of the present invention is to provide a radio base station that can reduce interference.

The radio base station according to an aspect of the present invention controls the transmission power of the physical uplink channel transmitted by the user apparatus. The radio base station receives at least one of an interference level in a plurality of cells formed in the vicinity of the own cell to which the user apparatus is connected or a reception communication quality in the user apparatus in the plurality of cells. An acquisition unit; and a power control unit that limits the transmission power when the interference level or the reception communication quality in the plurality of cells acquired by the reception state acquisition unit is within a predetermined range.

FIG. 1 is an overall schematic configuration diagram of a wireless communication system 10. FIG. 2 is a functional block configuration diagram of the eNB 100A. FIG. 3 is a functional block configuration diagram of UE 200B. FIG. 4A is an explanatory diagram of interference caused by air communication. FIG. 4B is an explanatory diagram of interference caused by air communication. FIG. 4C is an explanatory diagram of interference caused by air communication. FIG. 5A is a diagram illustrating a relationship between path loss (horizontal axis), Target SIR, number of allocated radio resource blocks (number of allocated RBs), and PUSCH transmission power (vertical axis). FIG. 5B is a diagram illustrating a relationship between path loss (horizontal axis), Target SIR, number of allocated radio resource blocks (number of allocated RBs), and PUSCH transmission power (vertical axis). FIG. 6A is an explanatory diagram of an example of radio resource block allocation to the UE 200B. FIG. 6B is an explanatory diagram of an example of radio resource block allocation to the UE 200B. FIG. 7 is a diagram illustrating the relationship between the maximum transmission power and the PHR. FIG. 8A is a diagram showing a relationship between path loss (horizontal axis) and PHR / ProhibithibiTimer value (vertical axis). FIG. 8B is a diagram illustrating a relationship between a path loss (horizontal axis) and a PHR / Prohibit Timer value (vertical axis). FIG. 9 is a diagram illustrating an example of separation of radio resource block areas. FIG. 10 is a diagram illustrating an uplink (PUSCH) transmission power control flow by the eNB 100A. FIG. 11 is a diagram illustrating a specific UE identification operation flow (operation example 1). FIG. 12 is a diagram illustrating a specific UE identification operation flow (operation example 2). FIG. 13 is a diagram illustrating a specific UE identification operation flow (operation example 3). FIG. 14 is a diagram illustrating an example of a hardware configuration of the eNB 100A, the bag 100B, and the UEs 200A to 200C.

Hereinafter, embodiments will be described with reference to the drawings. The same functions and configurations are denoted by the same or similar reference numerals, and description thereof is omitted as appropriate.

(1) Overall Schematic Configuration of Radio Communication System FIG. 1 is an overall schematic configuration diagram of a radio communication system 10 according to the present embodiment. The radio communication system 10 is a radio communication system according to Long Term Evolution (LTE).

The radio communication system 10 includes a radio access network 20,

radio base stations

100A, 100B (hereinafter, eNB100A, 及び 100B) and user devices 200A to 200C (hereinafter, UEs 200A to 200C).

The wireless access network 20 is an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) defined in 3GPP. Note that the radio communication system 10 is not necessarily limited to LTE (E-UTRAN). For example, the radio access network 20 may be a radio access network defined as 5G.

ENB100A, 100B and UE200A-200C execute wireless communication according to LTE specifications. eNB100A forms cell C1, and eNB100B forms cell C2.

ENB100A and eNB100B control the transmission power of the physical uplink channel transmitted by UEs 200A to 200C. Specifically, eNB100A and eNB100B control the transmission power of a physical uplink shared channel (PUSCH).

UE 200A is a normal UE, and performs radio communication with eNB 100A and eNB 100B on the ground or the like. UE200B and UE200C are mounted on a small unmanned flying object such as a drone, and perform radio communication with eNB100A and eNB100B not only on the ground but also above cells C1 and C2 (for example, at an altitude of 30 m or more). In this embodiment, UE200B and UE200C comprise a specific user apparatus (specific UE).

(2) Functional Block Configuration of Radio Communication System Next, a functional block configuration of the radio communication system 10 will be described. Specifically, the functional block configuration of the eNB 100A and the UE 200B will be described.

(2.1) eNB100A
FIG. 2 is a functional block configuration diagram of the eNB 100A. As illustrated in FIG. 2, the eNB 100A includes a radio signal transmission / reception unit 110, a reception state acquisition unit 120, a device identification unit 130, and a power control unit 140. Note that the eNB 100B has the same configuration as the eNB 100A.

The radio signal transmission / reception unit 110 transmits / receives a radio signal to / from the UE 200B (the same applies to other UEs). Specifically, the radio signal transmission / reception unit 110 transmits / receives various physical channels (control channel and shared channel) in accordance with LTE regulations.

The reception state acquisition unit 120 acquires the reception state of the UE 200B. Specifically, the reception state acquisition unit 120 can acquire interference levels in a plurality of cells (cells C1, C2) including the own cell (for example, the cell C1) to which the UE 200B is connected.

More specifically, the reception state acquisition unit 120 acquires interference levels in the own cell to which the UE 200B is connected (that is, the cell C1) and the neighboring cell (cell C2) formed in the vicinity of the own cell. To do. Note that the reception state acquisition unit 120 may acquire the interference power itself as the interference level, or perform interference using a ratio such as the signal level of the received signal from the SIR (Signal-to-Interference-Ratio) UE 200B set in the UE 200B. Electric power may be acquired.

Also, the reception state acquisition unit 120 can acquire the received communication quality at the UE 200B in the plurality of cells. Specifically, the reception state acquisition unit 120 acquires a downlink path loss as the received communication quality in the own cell and neighboring cells to which the UE 200B is connected. Note that the reception state acquisition unit 120 may acquire RSRP (Reference Signal Received Power) that can be a determination index similar to the path loss.

The device identification unit 130 identifies the type of the UE 200B. Specifically, the device identification unit 130 identifies whether or not the user device (UE) that performs wireless communication with the eNB 100A is a specific user device (specific UE) that can perform communication over the plurality of cells. .

More specifically, the device identification unit 130 identifies (i) identification using UE's IMEISV (International Mobile Equipment Identification Software Version) or contract type information, and (ii) separation by connection APN (Access Point Name). And (iii) Identification based on a measurement report from the UE can be performed. A specific identification procedure will be described later.

The power control unit 140 controls uplink transmission power transmitted by the UE 200B. In particular, in this embodiment, the power control unit 140 controls the transmission power of the physical uplink shared channel (PUSCH) transmitted by the UE 200B.

Specifically, the power control unit 140, when the interference level or the reception communication quality in the plurality of cells acquired by the reception state acquisition unit 120 is within a predetermined range (that is, when the possibility of being a specific UE is high) Limit transmit power.

That is, when the interference level of a plurality of cells (specifically, neighboring cells) is within a predetermined range (eg, xdBm range), power control section 140 limits the PUSCH transmission power to a predetermined value or less. For example, when the interference level of the cell C2 is −85 dBm and the predetermined range is set to −90 dBm, the power control unit 140 limits the transmission power of the PUSCH to a predetermined value or less. Similarly, when the quality (path loss) is within a predetermined range (for example, a ydB range), the transmission power of the PUSCH is limited to a predetermined value or less.

The power control unit 140 can limit the transmission power of the PUSCH to a predetermined value or less by the following method.

Specifically, the power control unit 140 limits the transmission power by setting the target reception quality (Target SIR) set for the UE 200B to a predetermined threshold value or less. Moreover, the power control unit 140 limits the transmission power by setting the number of radio resource blocks (number of RBs) allocated to the UE 200B to be equal to or less than a predetermined threshold.

Alternatively, the power control unit 140 limits the transmission power by suppressing transmission of a transmission power control command (TPC command) that instructs the UE 200B to increase the transmission power.

Further, the power control unit 140 limits the transmission power by setting a lower predetermined threshold as the above-described interference level (interference power) is higher. Similarly, the power control unit 140 limits the transmission power by setting a lower predetermined threshold value as the above-described received communication quality is better, specifically, as the path loss is smaller. Thereby, when the interference level is high or the path loss is small, the transmission power of the PUSCH can be kept lower.

The power control unit 140 can calculate the value of the limited transmission power based on the received communication quality (path loss), and can set the number of RBs equal to or less than a predetermined threshold according to the calculated transmission power. Specifically, power control section 140 sets the number of RBs corresponding to the transmission power calculated using the PUSCH transmission power calculation formula. A specific method for determining the number of RBs will be described later.

In addition, the power control unit 140 can use, as the above-described “predetermined threshold”, a predetermined threshold that is a predetermined fixed value or a predetermined threshold acquired from the outside via the wireless access network 20.

The power control unit 140 instructs the increase in the transmission power so that the surplus power with respect to the maximum transmission power of the uplink recognized by the UE 200B, specifically, PHR (Power Head Room) does not fall below the lower limit value. Suppresses command transmission. Further, when the PUSCH transmission power exceeds the upper limit value, the power control unit 140 suppresses transmission of a TPC command instructing an increase in transmission power.

Furthermore, the power control unit 140 suppresses substantial transmission of the TPC command by extending the transmission interval of the TPC command. Specifically, the power control unit 140 uses the TPC command “ProhibitTimer” to suppress transmission of the TPC command until the “Prohibit Timer” expires. A more specific method for suppressing transmission of the TPC command will be described later.

Further, the power control unit 140 can limit the transmission power of the PUSCH when the UE 200B is identified as the specific UE by the device identification unit 130. Specifically, when UE 200B is identified as a specific UE, power control section 140 limits the transmission power of PUSCH by any of the methods described above.

Further, as described above, when the interference level or the received communication quality in a plurality of cells is within a predetermined range, the power control unit 140 determines the area of the radio resource block allocated to the UE 200B (specific UE) as another user. It can isolate | separate from the area | region of the radio | wireless resource block allocated with respect to an apparatus, specifically UE200A which is normal UE.

Specifically, the power control unit 140 secures a radio resource block to which only a specific UE is allocated among radio resource blocks (frequency, time, etc.) that can be allocated to the UEs 200A to 200C. A specific radio resource block separation method will be described later.

(2.2) UE200B
FIG. 3 is a functional block configuration diagram of UE 200B. As illustrated in FIG. 3, the UE 200B includes a radio signal transmission / reception unit 210, a control signal reception unit 220, and a transmission power setting unit 230. UE 200C has the same configuration as UE 200B. Moreover, although UE200A also has a difference whether it is mounted in a drone, it has the structure substantially the same as UE200B.

The radio signal transmission / reception unit 210 transmits / receives radio signals to / from the eNB 100A and the eNB 100B. Specifically, the radio signal transmitting / receiving unit 210 transmits / receives various physical channels (control channel and shared channel) in accordance with LTE regulations.

The control signal receiving unit 220 receives a control signal transmitted from the eNB100A (or eNB100B, hereinafter the same). In particular, in the present embodiment, the control signal receiving unit 220 receives a control signal related to transmission power control of the UE 200B.

The transmission power setting unit 230 sets uplink transmission power based on a control signal related to transmission power control received by the control signal receiving unit 220. Specifically, the transmission power setting unit 230 sets various physical uplink channels (PUSCH, PUCCH, etc.) based on the control signal received by the control signal receiving unit 220 and sets the transmission power of the channel. To do.

(3) Operation of Radio Communication System Next, the operation of the radio communication system 10 will be described. Specifically, an operation when UE 200B and UE 200C mounted on the drone perform communication via cell C1 and cell C2 will be described. More specifically, an operation related to uplink (PUSCH) transmission power control for UE 200B and UE 200C will be described.

(3.1) Interference due to Over-Air Communication First, interference in the case where communication is performed over the cells C1 and C2 as in the UE 200B and UE 200C will be described.

4A, 4B, and 4C are explanatory diagrams of interference caused by over-the-air communication. As shown in FIG. 4A, since UE 200B flies over the sky, the prospect of connection with eNB 100A (solid arrow) is good, but the prospect of adjacent eNB 100B (dotted arrow) is also good.

For this reason, in the UE 200B, both the downlink path loss from the eNB 100A and the downlink path loss from the eNB 100B are reduced. As described above, when the path loss is small, in the current LTE specification, a high Target 向上 SIR is set to improve throughput.

As a result, the UE 200B becomes a high interference source for the eNB 100B (cell C2: see FIG. 1) and further other UEs located in the connection destination cell C1.

On the other hand, in a normal UE that generally performs communication on the ground, such as UE 200A, when the downlink path loss from the connected eNB 100A is small, the distance from the neighboring cell, that is, the eNB 100B is increased. Or there is a shielding object, the downlink path loss from the eNB 100B increases.

Furthermore, as shown in FIGS. 4B and 4C, when a plurality of specific UEs (UE 200B and UE 200C) are connected to different neighboring cells, each specific UE continues to increase its transmission power until it satisfies Target SIR. There is a possibility of giving a big interference to each other. 4B and 4C show a state in which UE 200B is connected to eNB 100A (solid arrow) and UE 200C is connected to eNB 100B (solid arrow).

Moreover, such a state also gives interference to other UEs (UE 200A) connected to the cell.

(3.2) Transmission Power Limitation Next, PUSCH transmission power limitation operation by eNB100A (eNB100B, hereinafter the same) will be described. Specifically, (i) restriction by target reception quality (Target SIR), (ii) restriction by number of radio resource blocks, (iii) restriction by transmission transmission control command (TPC command) transmission suppression, and (iv) radio The limitation due to the separation of the resource block allocation area will be described.

(3.2.1) Limitation of target reception quality In this case, the eNB 100A limits the target reception quality (Target SIR), that is, sets radio frequency resources below a predetermined threshold value, and executes scheduling of radio resources.

Specifically, the eNB 100A sets the Target SIR for the UE 200B (the same applies to the UE 200C). In general, in LTE specifications, Target SIR is changed according to the downlink path loss in UE 200B.

In this embodiment, the eNB 100A measures the interference level (interference power) in its own cell and exchanges information on the interference level between neighboring cells. Note that the eNB 100A may change Target SIR according to the interference level of the neighboring cell.

ENB100A sets a high Target SIR when the interference level of neighboring cells is low. On the other hand, when the interference level is high, the eNB 100A sets a low Target SIR.

In addition, in consideration of the case where UE 200B performs communication on the ground, Target SIR may be changed according to path loss (received communication quality). That is, when UE 200B is located on the ground, the path loss increases, so Target SIR is increased. That is, in such a case, there is no need to provide PUSCH transmission power restriction).

Also, the eNB 100A may associate the path loss with the Target SIR. For example, AdB if path loss (dB) ≦ X1, and BdB if X1 <path loss ≦ X2. Alternatively, the eNB 100A may define Target SIR as (A * path loss + B, A and B are variables), and set A and B according to the situation or the like.

Here, FIGS. 5A and 5B are diagrams showing the relationship between path loss (horizontal axis), Target SIR, number of allocated radio resource blocks (number of allocated RBs), and PUSCH transmission power (vertical axis).

As shown in FIGS. 5A and 5B, when the path loss is small, a low Target SIR is set, and when the path loss is large, a high Target SIR is set. An area where the path loss is small is an image applied to air communication (equivalent), and an area where the path loss is large is applied to ground communication (equivalent).

Note that, as shown in FIGS. 5A and 5B, the relationship between the path loss and the Target SIR may change stepwise (FIG. 5A) or may change continuously (FIG. 5B).

(3.2.2) Limitation on the number of radio resource blocks In this case, the eNB 100A limits the maximum number of radio resource blocks (number of RBs) allocated to the UE 200B, that is, sets the radio resource block to a predetermined threshold value or less to schedule radio resources. Execute.

Specifically, when performing scheduling of radio resources for the UE 200B, the eNB 100A allocates radio resource blocks equal to or less than the maximum number of allocated RBs. Also for the PUSCH, when the number of allocated RBs is increased, the transmission power increases. However, in this embodiment, the PUSCH transmission power is limited by providing an upper limit value for the number of RBs allocated in units of subframes.

Hereinafter, the description of the operation similar to the above-described target reception quality restriction (see 3.2.1) will be omitted.

ENB100A sets a high maximum number of allocated RBs when the interference level of neighboring cells is low. On the other hand, when the interference level is high, eNB 100A sets a low maximum allocation RB number. Note that the eNB 100A may change the maximum number of RBs allocated according to the interference level of neighboring cells.

Here, FIGS. 6A and 6B are explanatory diagrams of examples of radio resource block allocation to the UE 200B. As shown in FIGS. 6A and 6B, the eNB 100A notifies the UE 200B that 10 RBs (usually 100 RBs) are allocated per subframe using ULGrant. UE 200B transmits PUSCH using the notified 10RB. Since there are few radio resource blocks to be used, the transmission power is reduced as a result.

In consideration of the case where UE 200B performs communication on the ground, the maximum number of allocated RBs may be changed according to path loss (received communication quality). That is, when UE 200B is located on the ground, the path loss increases, so the maximum number of allocated RBs is increased. That is, in such a case, there is no need to provide PUSCH transmission power restriction).

Also, the eNB 100A may associate the path loss with the maximum number of allocated RBs. For example, A (RB) if path loss (dB) ≦ X1, B (RB) if X1 <path loss ≦ X2, and so on. Alternatively, the eNB 100A may define the maximum number of allocated RBs as (A * path loss + B, A and B are variables), and set A and B according to the situation or the like.

The relationship between the path loss and the number of allocated radio resource blocks is as shown in FIGS. 5A and 5B.

Furthermore, the eNB 100A may determine the maximum number of allocated RBs using a predetermined transmission power as an input value. Specifically, eNB100A calculates the value of the transmission power after a restriction | limiting based on a path loss using the following numerical formula, and determines the maximum number of allocation RB according to the calculated transmission power. The following formulas are defined in 3GPP TS36.213 5.1.1.

The eNB100A recognizes the number of allocated RBs (M _PUSCH ), transmission power offset (P _{O_PUSCH} ), transmission power coefficient (α) according to path loss, path loss (PL), and accumulated value (f (i)) of TPC commands. Therefore, PUSCH transmission power (P _PUSCH ) can be estimated (calculated). Therefore, the eNB 100A can determine the number of allocated RBs (M _PUSCH ) so that the calculated transmission power of the _PUSCH is obtained.

(3.2.3) Transmission suppression of transmission power control command In this case, the eNB 100A suppresses transmission of the transmission power control command (TPC command), but specifically, executes the following three controls. That is, (i) the transmission of the increase instruction (plus) is suppressed with reference to the surplus power (PHR) with respect to the maximum transmission power of the uplink, and (ii) the increase instruction (plus) with reference to the uplink transmission power. ) TPC command transmission is suppressed, and (iii) TPC command transmission interval is extended using a Prohibit Timer. More specific description will be given below.

(3.2.3.1) PHR standard eNB100A suppresses transmission of a TPC command so that PHR (Power Head Room) may not become below a lower limit.

FIG. 7 shows the relationship between maximum transmission power and PHR. As shown in FIG. 7, PHR is the difference between the maximum uplink transmission power and the transmission power of the current uplink (specifically PUSCH) of the UE. If PHR is small, it means that transmission is performed with high transmission power.

ENB100A suppresses transmission of a positive TPC command when PHR is likely to be less than a predetermined lower limit. That is, a negative (decrease instruction) TPC command may be transmitted.

ENB 100A sets a lower lower limit value of PHR that suppresses transmission of a positive TPC command when the interference level of a neighboring cell is low. On the other hand, when the interference level is high, eNB 100A sets the lower limit value of PHR to be large. Note that the eNB 100A may change the PHR according to the interference level of neighboring cells.

Note that the lower limit value of PHR may be changed according to path loss (received communication quality) in consideration of the case where UE 200B performs communication on the ground. That is, when UE 200B is located on the ground, the path loss increases, so the lower limit value of PHR is reduced. That is, in such a case, there is no need to provide PUSCH transmission power restriction).

Specifically, eNB100A determines the value (PH) of PHR using the following numerical formula. The following formulas are defined in 3GPP TS36.213 5.1.2.

P _CMAX is the maximum transmission power of the UE, and the part enclosed in {} is the current transmission power of the UE.

ENB100A may associate the path loss with the lower limit value of PHR. For example, AdB if path loss (dB) ≦ X1, and BdB if X1 <path loss ≦ X2. Alternatively, the eNB 100A may define PHR as (A * path loss + B, A and B are variables), and set A and B according to the situation or the like.

8A and 8B are diagrams showing the relationship between the path loss (horizontal axis) and the PHR / Prohibit ・ Timer value (vertical axis).

8A and 8B, when the path loss is small, a lower limit value of a large PHR is set, and when the path loss is increased, a lower limit value of a small PHR is set. An area where the path loss is small is an image applied to air communication (equivalent), and an area where the path loss is large is applied to ground communication (equivalent).

As shown in FIGS. 8A and 8B, the relationship between the path loss and the lower limit value of PHR may change stepwise (FIG. 8A) or may change continuously (FIG. 8B).

(3.2.3.2) Uplink Transmission Power Reference The eNB 100A suppresses transmission of a TPC command when the uplink (PUSCH) transmission power exceeds the upper limit.

In the transmission power control by the TPC command, a plus or minus command is transmitted so as to eliminate the difference between the required target power of the UE 200B and the current received power. For example, when the required target power is 10 dBm and the current reception quality (reception power) is 7 dBm, a TPC command for +3 dB is transmitted. Thereby, the transmission power of UE 200B increases.

In the present embodiment, when the transmission power of the PUSCH by the UE 200B exceeds the upper limit value, the eNB 100A stops transmitting a positive TPC command even if the reception quality does not reach the required target power.

ENB100A sets a high upper limit value when the interference level of neighboring cells is low. On the other hand, when the interference level is high, eNB 100A sets a low upper limit value. In addition, eNB100A may change an upper limit according to the interference level of a neighboring cell.

Note that the upper limit value may be changed according to the path loss (received communication quality) in consideration of the case where the UE 200B performs communication on the ground. That is, when UE 200B is located on the ground, the path loss increases, so the upper limit value is increased. That is, in such a case, there is no need to provide PUSCH transmission power restriction).

Also, the eNB 100A may associate the path loss with the upper limit value of transmission power. For example, if the path loss (dB) ≦ X1, AdBm, and if X1 <path loss ≦ X2, BdBm or the like. Alternatively, the eNB 100A may define the upper limit value as (A * path loss + B, A and B are variables), and set A and B according to the situation or the like.

The relationship between path loss and transmission power (upper limit) is as shown in FIGS. 5A and 5B.

(3.2.2.3) Extending TPC Command Transmission Interval Using Prohibit Timer The eNB 100A extends the TPC command transmission interval using the Prohibit Timer that measures the period during which TPC command transmission is prohibited.

ENB100A recognizes the transmission timing of the TPC command transmitted to UE200B. eNB100A starts the Prohibit Timer in response to the transmission of the TPC command, and allows the transmission of the TPC command when the predetermined time has elapsed since the most recent TPC command transmission, that is, when the Prohibit Timer has expired. To do.

On the other hand, when the Prohibit Timer has not expired, the eNB 100A does not allow the transmission of the TPC command even when a positive TPC command transmission is required. In particular, when positive TPC commands are continuously transmitted in a short period of time, PUSCH transmission increases rapidly. In this embodiment, such a rapid increase in transmission power is prevented.

ENB100A sets short Prohibit Timer when the interference level of neighboring cells is low. On the other hand, when the interference level is high, the eNB 100A sets a long Prohibit Timer. Note that the eNB 100A may change the setting time of the Prohibit Timer (Prohibit Timer value) according to the interference level of the neighboring cell.

In addition, considering the case where UE 200B performs communication on the ground, the setting time of the Prohibit Timer may be changed according to the path loss (received communication quality). That is, when UE 200B is located on the ground, the path loss increases, so the Prohibit Timer value is shortened. That is, in such a case, there is no need to provide PUSCH transmission power restriction).

ENB100A may associate the path loss with the Prohibit Timer value. For example, Ams if the path loss (dB) ≦ X1, Bms if X1 <Path loss ≦ X2. Alternatively, the eNB 100A may define the Prohibit Timer value as (A * path loss + B, A and B are variables), and set A and B according to the situation or the like.

The relationship between the path loss and the Prohibit Timer value is as shown in FIGS. 8A and 8B.

(3.2.4) Separation of Radio Resource Block Allocation Area The eNB 100A assigns the radio resource block area allocated to the UE 200B, that is, the specific UE to another user apparatus, that is, a normal UE (UE 200A). The radio resource block is separated from the allocated radio resource block area, and radio resource scheduling is executed.

Specifically, eNB100A isolate | separates beforehand the radio | wireless resource block area (RB area | region) allocated to normal UE, and the RB area | region allocated to specific UE.

FIG. 9 shows an example of separation of radio resource block areas. As illustrated in FIG. 9, the entire RB area (for example, 100 RBs) is separated into an RB area A1 assigned to a normal UE and an RB area A2 assigned to a specific UE.

The separation position between the RB area A1 and the RB area A2 may be fixed or variable. For example, the RB area A2 may be changed according to the ratio of the number of specific UEs to the number of UEs connected (waiting) to the eNB 100A. Specifically, eNB100A may determine the size of RB area | region A2 using the following formula | equation. In addition, (alpha) is UE ratio coefficient and can set arbitrary values.

RB area A2 = (number of RBs in the entire band) * α * (number of specific UEs / (number of specific UEs + number of normal UEs))
Moreover, eNB100A may isolate | separate RB area | region, when a specific UE is detected, without isolate | separating RB area | region at the time of starting of eNB100A. Furthermore, when the connection of the specific UE is released, the eNB 100A may return to a state where the RB area is not separated.

As the RB areas are separated in this way, the eNB 100A assigns RBs in the RB area A1 to normal UEs and assigns RBs in the RB area A2 to specific UEs.

(3.3) Transmission Power Control Flow FIG. 10 shows an uplink (PUSCH) transmission power control flow by the eNB 100A. As illustrated in FIG. 10, the eNB 100A acquires the interference level (interference power) in each cell (own cell and neighboring cells) or the received communication quality (path loss) at the UE 200B in the plurality of cells (S10).

ENB 100A determines whether the interference level or the received communication quality in the plurality of cells is within a predetermined range (S20). Specifically, as described above, the eNB 100A determines that the interference level of the plurality of cells is within a predetermined range (for example, a range of xdBm), or the path loss of the plurality of cells is a predetermined range (for example, a range of ydB). ).

When the interference level or the path loss of the plurality of cells is within a predetermined range, the eNB 100A calculates a PUSCH transmission power limit value (S30). The specific transmission power limit value is determined by any of the methods described above. Alternatively, the transmission power value and the limit value (specifically, various predetermined threshold values, upper limit values, and lower limit values) may be values acquired from the outside via the radio access network 20.

ENB100A instructs UE200B on the determined transmission power (S40). Specifically, a parameter for determining PUSCH transmission power is notified by broadcast information. In the case of a TPC command, UL Grant is used as described above.

(3.4) Identification of specific UE Next, a method for identifying a specific UE will be described. Specifically, as described above, the eNB 100A is based on (i) identification using UE's IMEISV (International Mobile Equipment Identity Software Version) or contract type information, and (ii) separation of connection destination APN (Access Point Name). Identification and (iii) identification based on a measurement report from the UE can be performed.

(3.4.1) Operation example 1
FIG. 11 shows a specific UE identification operation flow (operation example 1). As illustrated in FIG. 11, the eNB 100A acquires IMEISV or contract type information (S110). Based on IMEISV or contract type information, the type of UE (whether it is a UE installed in a drone or not) can be identified.

The eNB 100A determines whether or not the transmission power control target UE is a specific UE based on the acquired IMEISV or contract type information (S120).

When it is determined that the UE whose transmission power is to be controlled is the specific UE, the eNB 100A controls the transmission power of the PUSCH as the specific UE (S130).

(3.4.2) Operation example 2
FIG. 12 shows a specific UE identification operation flow (operation example 2). Hereinafter, parts different from the operation example 1 will be mainly described.

As shown in FIG. 12, the eNB 100A separates the network to which the UE is connected, specifically, the APN (Access Point Name) according to the type of the UE (S210). That is, the specific UE is separated into an APN associated with the specific UE. Thereby, the classification of UE (whether it is UE mounted in the drone etc.) can be identified.

The processing of S220 and S230 is the same as S120 and S130.

(3.4.3) Operation example 3
FIG. 13 shows a specific UE identification operation flow (operation example 3). Hereinafter, parts different from the operation example 1 will be mainly described.

As shown in FIG. 13, the eNB 100A acquires a measurement report (Measurement Report) transmitted from the UE 200B (and other UEs) (S310).

The eNB 100A determines whether or not the acquired measurement report includes measurement results for a predetermined number (N) or more of cells (S320). Further, the eNB 100A determines whether or not the difference between the RSRP (Reference Signal Received Power) of the neighboring cell and the RSRP of the own cell is equal to or less than a predetermined value based on the acquired measurement report (S330).

When the measurement results for a predetermined number (N) or more of cells are included, or when the difference between the RSRP of the neighboring cell and the RSRP of the own cell is equal to or less than the predetermined value, the eNB 100A determines the PUSCH as the specific UE. The transmission power is controlled (S340).

(4) Action / Effect According to the above-described embodiment, the following action / effect can be obtained. Specifically, the eNB 100A (eNB 100B, hereinafter the same), the PUSCH when the interference level or path loss (reception communication quality) in the plurality of cells (cells C1, C2) acquired by the reception state acquisition unit 120 is within a predetermined range. Transmission power (hereinafter simply referred to as transmission power) is limited.

For this reason, in order to perform communication in the sky, such as UE200B and UE200C, the visibility with multiple cells is improved, and the interference level (interference power) or path loss in multiple cells is within a predetermined range (for example, within xdBm (in the case of interference power) ) Or within ydB (in the case of path loss)), it is possible to determine UE 200B and UE 200C as specific UEs and limit transmission power.

Thereby, even when UE200B and UE200C mounted on the drone have the same communication environment as a plurality of cells due to good visibility, interference by the user apparatus can be reduced.

In this embodiment, eNB100A (power control part 140) makes the number of radio | wireless resource blocks allocated with respect to Target SIR or specific UE set with respect to specific UE below a predetermined threshold, or with respect to specific UE Limit transmission power by suppressing transmission of TPC commands. For this reason, the transmission power can be controlled using an appropriate parameter from among the parameters in which the transmission power changes, instead of directly controlling the transmission power. This can contribute to flexible and easy realization of transmission power control.

In this embodiment, the eNB 100A (power control unit 140) limits the transmission power by setting a lower predetermined threshold as the interference level (interference power) is higher. Further, the eNB 100A (power control unit 140) limits the transmission power by setting a lower predetermined threshold as the path loss is smaller. For this reason, even when there is a possibility that interference with other cells or the like may increase, the interference can be reliably suppressed.

In the present embodiment, the eNB 100A (power control unit 140) can calculate the value of the limited transmission power, and can set the number of RBs equal to or less than a predetermined threshold according to the calculated transmission power. For this reason, reliable transmission power control can be realized without exceeding the desired transmission power.

In this embodiment, eNB100A (power control part 140) suppresses transmission of a TPC command so that PHR with respect to the maximum transmission power of the uplink recognized by the specific UE does not become the lower limit value or less.
Moreover, eNB100A (power control part 140) suppresses transmission of a TPC command, when transmission power exceeds an upper limit. For this reason, reliable transmission power control can be realized without exceeding the desired transmission power.

Moreover, in this embodiment, eNB100A (power control part 140) suppresses transmission of a substantial TPC command by extending the transmission interval of a TPC command. Because of this
The transmission power can be limited without greatly changing the transmission power control mechanism by the TPC command. This is particularly effective when positive TPC commands are continuously transmitted in a short period of time.

In the present embodiment, the eNB 100A (power control unit 140) can use a predetermined threshold defined in advance or a predetermined threshold acquired from the outside. For this reason, it is possible to suppress the processing load associated with the limitation of transmission power and to realize uniform limitation of transmission power as the entire radio access network 20.

In the present embodiment, the eNB 100A (power control unit 140) can limit the transmission power based on the fact that the target UE is identified as a specific UE by the device identification unit 130. For this reason, even if it does not compare the interference level or path loss etc. in several cells, it can identify that it is specific UE quickly and reliably.

In the present embodiment, the radio resource block area allocated to a specific UE can be separated from the radio resource block area allocated to another user apparatus (normal UE). For this reason, it is possible to minimize the influence on interference and radio resource block allocation for a normal UE.

(5) Other Embodiments Although the contents of the present invention have been described above according to the embodiments, the present invention is not limited to these descriptions, and various modifications and improvements are possible. It is obvious to the contractor.

For example, in the above-described embodiment, UE 200B and UE 200C are mounted on a drone, but UE 200B and UE 200C may not necessarily be mounted on a flying object such as a drone. That is, the present invention can also be applied to a normal user device such as a smartphone. For example, when the user apparatus is located in a place where a line-of-sight with a plurality of cells is good and a path loss in a downlink from the plurality of cells is small, the above-described transmission power control may be executed. For example, the user device is located on a higher floor of a building where an unspecified user may communicate. The same applies to a user device (MTC-UE) connected to a weather sensor or a monitoring camera installed on the roof of a building.

Further, the block diagrams (FIGS. 2 and 3) used in the description of the above-described embodiment are functional block diagrams. These functional blocks (components) are realized by any combination of hardware and / or software. Further, the means for realizing each functional block is not particularly limited. That is, each functional block may be realized by one device physically and / or logically coupled, and two or more devices physically and / or logically separated may be directly and / or indirectly. (For example, wired and / or wireless) and may be realized by the plurality of devices.

Furthermore, the above-described

eNB

100A, 100B, and UE 200A to 200C (the device) may function as a computer that performs transmission power control processing according to the present invention. FIG. 14 is a diagram illustrating an example of a hardware configuration of the apparatus. As shown in FIG. 14, the apparatus may be configured as a computer apparatus including a processor 1001, a memory 1002, a storage 1003, a communication apparatus 1004, an input apparatus 1005, an output apparatus 1006, a bus 1007, and the like.

Each functional block (see FIGS. 2 and 3) of the device is realized by any hardware element of the computer device or a combination of the hardware elements.

The processor 1001 controls the entire computer by operating an operating system, for example. The processor 1001 may be configured by a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic device, a register, and the like.

The memory 1002 is a computer-readable recording medium and includes, for example, at least one of ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), RAM (Random Access Memory), and the like. May be. The memory 1002 may be called a register, a cache, a main memory (main storage device), or the like. The memory 1002 can store a program (program code) that can execute the method according to the above-described embodiment, a software module, and the like.

The storage 1003 is a computer-readable recording medium such as an optical disc such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disc, a magneto-optical disc (eg a compact disc, a digital versatile disc, a Blu-ray). (Registered trademark) disk, smart card, flash memory (for example, card, stick, key drive), floppy (registered trademark) disk, magnetic strip, and the like. The storage 1003 may be referred to as an auxiliary storage device. The recording medium described above may be, for example, a database including a memory 1002 and / or a storage 1003, a server, or other suitable medium.

The communication device 1004 is hardware (transmission / reception device) for performing communication between computers via a wired and / or wireless network, and is also referred to as a network device, a network controller, a network card, a communication module, or the like.

The input device 1005 is an input device (for example, a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that accepts an input from the outside. The output device 1006 is an output device (for example, a display, a speaker, an LED lamp, or the like) that performs output to the outside. Note that the input device 1005 and the output device 1006 may have an integrated configuration (for example, a touch panel).

Also, each device such as the processor 1001 and the memory 1002 is connected by a bus 1007 for communicating information. The bus 1007 may be configured with a single bus or may be configured with different buses between apparatuses.

Further, the information notification is not limited to the above-described embodiment, and may be performed by other methods. For example, notification of information includes physical layer signaling (eg, DCI (Downlink Control Information), UCI (Uplink Control Information)), upper layer signaling (eg, RRC signaling, MAC (Medium Access Control) signaling, broadcast information (MIB ( Master (Information Block), SIB (System Information Block)), other signals, or combinations thereof, and RRC signaling may also be referred to as RRC messages, eg, RRC Connection Connection message, RRC It may be a Connection など Reconfiguration message.

Furthermore, input / output information may be stored in a specific location (for example, a memory) or may be managed by a management table. The input / output information can be overwritten, updated, or appended. The output information may be deleted. The input information may be transmitted to other devices.

As long as there is no contradiction, the order of the sequences and flowcharts in the above-described embodiment may be changed.

In the above-described embodiment, the specific operation that is performed by the eNB 100A (eNB 100B, hereinafter the same) may be performed by another network node (device). Further, the function of the eNB 100A may be provided by a combination of a plurality of other network nodes.

Note that the terms described in this specification and / or terms necessary for understanding this specification may be replaced with terms having the same or similar meaning. For example, a channel and / or symbol may be a signal (signal) if there is a corresponding description. The signal may be a message. Also, the terms “system” and “network” may be used interchangeably.

Further, the parameter or the like may be represented by an absolute value, may be represented by a relative value from a predetermined value, or may be represented by other corresponding information. For example, the radio resource may be indicated by an index.

ENB100A (base station) can accommodate one or a plurality of (for example, three) cells (also referred to as sectors). When a base station accommodates multiple cells, the entire coverage area of the base station can be partitioned into multiple smaller areas, each smaller area being a base station subsystem (eg, indoor small base station RRH: Remote Radio Head) can also provide communication services.

The term “cell” or “sector” refers to part or all of the coverage area of a base station and / or base station subsystem that provides communication services in this coverage.
Further, the terms “base station”, “eNB”, “cell”, and “sector” may be used interchangeably herein. A base station may also be referred to in terms such as a fixed station, NodeB, eNodeB (eNB), access point, femtocell, small cell, and the like.

UE 200A-200C is a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, It may also be referred to as a wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other appropriate terminology.

As used herein, the phrase “based on” does not mean “based only on”, unless expressly specified otherwise. In other words, the phrase “based on” means both “based only on” and “based at least on.”

Also, the terms “including”, “comprising”, and variations thereof are intended to be inclusive, as well as “comprising”. Further, the term “or” as used herein or in the claims is not intended to be an exclusive OR.

Any reference to elements using designations such as “first”, “second”, etc. as used herein does not generally limit the amount or order of those elements. These designations can be used herein as a convenient way to distinguish between two or more elements. Thus, a reference to the first and second elements does not mean that only two elements can be employed there, or that in some way the first element must precede the second element.

Throughout this specification, if articles are added by translation, for example, a, an, and the in English, these articles must be clearly indicated not in context. , Including multiple items.

As described above, the embodiments of the present invention have been described. However, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

According to the radio base station described above, even when a user environment such as a user device mounted on a drone has a good outlook and a communication environment similar to that of a plurality of cells, interference by the user device can be reduced, which is useful. .

10 Wireless communication system 20

Wireless access network

100A, 100B eNB
110 Radio signal transmission / reception unit 120 Reception status acquisition unit 130 Device identification unit 140 Power control unit 200A to 200C UE
210 Radio signal transmission / reception unit 220 Control signal reception unit 230 Transmission power setting unit C1, C2 Cell 1001 Processor 1002 Memory 1003 Storage 1004 Communication device 1005 Input device 1006 Output device 1007 Bus

Claims

A radio base station that controls transmission power of a physical uplink channel transmitted by a user apparatus,
A reception state acquisition unit that acquires at least one of an interference level in a plurality of cells formed in the vicinity of the own cell to which the user apparatus is connected, or a reception communication quality in the user apparatus in the plurality of cells;
A radio base station comprising: a power control unit that limits the transmission power when the interference level or the reception communication quality in the plurality of cells acquired by the reception state acquisition unit is within a predetermined range.
The power control unit sets a target reception quality set for the user apparatus or a number of radio resource blocks allocated to the user apparatus to be equal to or less than a predetermined threshold, or increases transmission power to the user apparatus. The radio base station according to claim 1, wherein the transmission power is limited by suppressing transmission of a transmission power control command instructing the transmission power.
The radio base station according to claim 2, wherein the power control unit limits the transmission power by setting the predetermined threshold value lower as the interference level is higher.
The radio base station according to claim 2, wherein the power control unit limits the transmission power by setting the predetermined threshold value lower as the reception communication quality is better.
The power control unit calculates a value of the limited transmission power based on the received communication quality, and sets the number of radio resource blocks equal to or less than the predetermined threshold according to the calculated transmission power. The radio base station described in 1.
The radio base according to claim 2, wherein the power control unit suppresses transmission of the transmission power control command so that surplus power with respect to maximum transmission power does not become a lower limit value or when the transmission power exceeds an upper limit value. Bureau.
The radio base station according to claim 2, wherein the power control unit suppresses transmission of the transmission power control command by extending a transmission interval of the transmission power control command.
The radio base station according to any one of claims 2 to 6, wherein the power control unit uses the predetermined threshold defined in advance or the predetermined threshold acquired from the outside.
The power control unit allocates an area of a radio resource block allocated to the user apparatus to another user apparatus when the interference level or the received communication quality in the plurality of cells is within the predetermined range. The radio base station according to claim 1, wherein the radio base station is separated from an area of a radio resource block to be generated.