JP5668314B2 - Base station equipment - Google Patents

Description

  The present invention relates to a base station apparatus.

The base station apparatus includes a scheduler that performs scheduling for determining radio resources (frequency, time, etc.) allocated to the terminal apparatus.
The scheduler can appropriately determine allocation of radio resources to each terminal according to radio wave conditions and the like.

  In LTE (Long Term Evolution), the scheduler is configured as a wireless communication MAC (Media Access Control; second layer) function, that is, a MAC scheduler.

  Here, FIG. 9 shows a layer structure related to radio communication of the base station apparatus in LTE. The layer structure in FIG. 9 includes a PHY (Physical Layer) that is a first layer related to wireless communication, and a MAC as an upper layer. The scheduler is a function of the MAC.

Above the MAC, RLC (Radio Link Control) / PDCP (Packet Data Convergence Protocol) is arranged. RLC (Radio Link Control) has a signal retransmission function and the like, and PDCP (Packet Data Convergence Protocol) has a security function and the like (see Non-Patent Document 1).

Furthermore, RRC (Radio Resource Control), RRM (Radio Resource Management), and NAS (Non-Access Stratum) are arranged above RLC / PDCP.
Thus, in LTE, functions related to radio resource management such as RRC (Radio Resource Control) and RRM (Radio Resource Management) are arranged in the base station apparatus.

  The RRM included in the upper layer of the MAC manages radio resources and provides information necessary for scheduling (scheduling information) to the MAC scheduler. The scheduling information provided from the RRM includes QoS (Quality of Service) information.

  The PHY, which is a lower layer of the MAC, acquires CQI (Channel Quality Indicator) information, and the CQI information may be provided as scheduling information to the MAC scheduler.

Takeshi Hattori, edited by Masanobu Fujioka, HSPA + / LTE / SAE textbook, Impress R & D, Inc., issued on August 1, 2009, pp140

  The scheduling by the scheduler is required to be performed at high speed. For example, in LTE, allocation information of resource blocks (minimum unit of resource allocation), which is a radio resource, is stored in each radio subframe, and the subframe cycle is 1 msec.

Therefore, the MAC and the scheduler included in the MAC need to operate at a period of 1 msec which is a period of the subframe. That is, it is desirable that the scheduling of each subframe is completed within 1 msec. If the scheduling is not completed within 1 msec, there is a possibility that appropriate scheduling cannot be performed.

  Here, since the scheduler is included in the MAC, the MAC acquires scheduling information from functions of other layers such as RRM, and the scheduler performs scheduling using the scheduling information acquired by the MAC. Will do.

The MAC performs various processes other than the process for handling the scheduling information. Therefore, when the MAC is also responsible for processing the scheduling information, the MAC processing load increases.
When the processing load of the MAC increases, it becomes difficult for the MAC to operate in a 1 msec cycle that is a subframe cycle. As a result, it becomes difficult for the scheduler arranged in the MAC to perform appropriate scheduling.

On the other hand, when trying to cope with an increase in the processing load of the MAC, it is necessary to increase the clock speed of the processing processor that realizes the function as the MAC, resulting in an increase in the cost of the base station apparatus.

  The present invention has been made in view of such a problem, and an object of the present invention is to make it possible to quickly handle information in a scheduler while suppressing an increase in MAC load.

(1) The present invention includes a MAC unit that performs processing of a MAC layer for wireless communication, a scheduler that performs scheduling for determining allocation of radio resources, and a radio resource management unit that manages radio resources. Is a base station apparatus connected to the radio resource management unit so that information can be acquired from the radio resource management unit without going through the MAC unit.

  According to the present invention, since the scheduler can acquire information without going through the MAC unit, it can acquire necessary information from the radio resource management unit while avoiding a delay due to going through the MAC unit. Moreover, since the information does not pass through the MAC unit, an increase in the load on the MAC unit can be suppressed.

(2) Preferably, the scheduler is configured to acquire scheduling information required for performing the scheduling from the radio resource management unit without passing through the MAC unit. In this case, the scheduler can acquire scheduling information from the radio resource management unit without going through the MAC unit.

(3) The radio resource management unit is configured to exchange information between base station devices via a communication interface between base stations, and the scheduler is configured such that the radio resource management unit uses the communication interface between base stations. It is preferable to acquire information acquired from another base station apparatus via the scheduling information. In this case, scheduling using information acquired from another base station apparatus can be performed.

(4) The scheduling information includes interference control information used for interference control for suppressing inter-cell interference, and the scheduler uses the interference control information to suppress inter-cell interference. It is preferable to perform the scheduling. In this case, the scheduler can perform scheduling so as to suppress interference.

(5) Preferably, the scheduler is configured to give allocation information indicating a radio resource allocation result to the radio resource management unit without passing through the MAC unit. In this case, the scheduler can quickly give the allocation information to the radio resource management unit without going through the MAC unit.

(6) It is preferable that the radio resource management unit is configured to transmit the allocation information acquired from the scheduler to another base station apparatus via an inter-base station communication interface. In this case, the radio resource management unit can transmit the quickly acquired allocation information to another base station apparatus without going through the MAC unit. Therefore, other base station apparatuses can acquire allocation information quickly.

(7) The scheduler is connected to the PHY unit so that information can be given to a PHY unit that performs processing of a PHY layer that is a lower layer of the MAC layer without going through the MAC unit. Is preferred. In this case, the scheduler can quickly provide necessary information to the PHY unit without going through the MAC unit.

(8) Preferably, the scheduler is configured to give allocation information indicating a radio resource allocation result to the PHY unit without passing through the MAC unit. In this case, the scheduler can quickly give the allocation information to the PHY unit without going through the MAC unit.

(9) It is preferable that the scheduler is connected to the PHY unit so that information can be acquired from the PHY unit without using the MAC unit. In this case, the scheduler can quickly acquire necessary information from the PHY unit without going through the MAC unit.

(10) The PHY unit is configured to generate scheduling information required for performing the scheduling from a received signal, and the scheduler generates the scheduling information without passing through the MAC unit. It is preferably configured to acquire from the PHY section. In this case, the scheduler can quickly acquire the scheduling information generated by the PHY unit from the PHY unit.

(11) The present invention viewed from another viewpoint includes a MAC unit that performs processing of a MAC layer for wireless communication, a scheduler that performs scheduling for determining radio resource allocation, a radio resource management unit that manages radio resources, The base station apparatus is characterized in that the scheduler is connected to the radio resource management unit so that information can be given to the radio resource management unit without going through the MAC unit. .
According to the present invention, the scheduler can quickly provide necessary information to the radio resource management unit without using the MAC unit.

(12) The present invention viewed from another point of view includes a MAC unit that performs processing of a MAC layer for wireless communication, a PHY unit that performs processing of a PHY layer of wireless communication, and a scheduler that performs scheduling for determining assignment of wireless resources, , And the scheduler is connected to the PHY unit so that information can be given to the PHY unit without going through the MAC unit.
According to the present invention, the scheduler can quickly provide necessary information to the PHY unit without using the MAC unit.

(13) The present invention from another viewpoint includes a MAC unit that performs processing of a MAC layer for wireless communication, a PHY unit that performs processing of a PHY layer of wireless communication, and a scheduler that performs scheduling for determining assignment of wireless resources, , And the scheduler is connected to the PHY unit so that information can be acquired from the PHY unit without going through the MAC unit.
According to the present invention, the scheduler can quickly acquire necessary information from the PHY unit without going through the MAC unit.

  According to the present invention, it is possible to quickly handle information in the scheduler while suppressing an increase in the load on the MAC.

It is the schematic which shows the structure of the radio | wireless communications system provided with the base station apparatus which concerns on embodiment of this invention. It is the schematic which shows the DL frame structure of LTE. It is a block diagram which shows the structure of a base station apparatus. It is a figure explaining the flow of information in a base station apparatus. It is a figure which shows the scheduler main-body part of a MAC scheduler. It is a figure which shows a data information scheduler. It is a figure which shows a VoIP scheduler. It is a figure which shows the example of electric power allocation. It is a layer structure figure of a base station apparatus.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a configuration of a wireless communication system including a base station apparatus according to an embodiment of the present invention. The radio communication system according to the present embodiment is a system for mobile phones to which, for example, LTE (Long Term Evolution) is applied, and communication based on LTE is performed between each base station device and a terminal device. . However, the communication method is not limited to LTE.

  This wireless communication system includes a plurality of base station devices 1. A terminal device 2 (mobile terminal; Mobile Station) can communicate with any one of the base station devices 1 by wireless connection.

  The base station apparatus 1 provided in the wireless communication system includes, for example, a macro base station apparatus (Macro Base Station) 1a that forms a communication area (macro cell) MC having a size of several kilometers, and is installed in the macro cell MC. A plurality of femto base station apparatuses (Femto Base Stations) 1b forming a relatively small femtocell FC of about 10 meters are provided.

A macro base station apparatus (hereinafter also referred to as “macro BS”) 1a can perform wireless communication with a terminal apparatus 2 in its own macro cell MC.
Further, the femto base station apparatus (hereinafter also referred to as “femto BS”) 1b is disposed, for example, in a place where it is difficult to receive the radio wave of the macro BS 1a, for example, indoors, and forms the femto cell FC.

The femto BS 1b can perform wireless communication with a terminal device (hereinafter also referred to as “MS”) 2 in the femto cell FC formed by the femto BS 1b. In this system, even in a place where it is difficult to receive the radio wave of the macro BS 1a, a service with sufficient throughput is provided to the MS 2 by installing the femto BS 1b that forms a relatively small femto cell FC in the place. Enable.
In the following description, the MS 2 connected to the femto BS 1b is also referred to as a femto MS 2b, and the MS 2 connected to the macro BS 1a is also referred to as a macro MS 2a.

  The plurality of base station apparatuses 1a, 1b, and 1b can exchange information through an inter-base station communication interface called an X2 interface. This inter-base station communication interface is constituted by a wired network, and is used for transmitting scheduling information, which will be described later, from one base station apparatus to another base station apparatus.

  In LTE, a frequency division duplex (FDD) scheme is adopted, and between an uplink signal (a transmission signal from a terminal device to a base station device) and a downlink signal (a transmission signal from the base station device to the terminal device). Thus, uplink communication and downlink communication can be performed simultaneously by assigning different use frequencies.

  Even in a plurality of different cells, communication may be performed using the same frequency. Therefore, inter-cell interference may occur between a plurality of cells (particularly between the macro cell MC and the femto cell FC). Inter-cell interference means that a transmission signal from a certain base station device becomes an interference signal to a terminal device connected to another base station device, or a transmission signal from a terminal device connected to a certain base station device It may be an interference signal to the base station apparatus.

  Such inter-cell interference is particularly likely to occur when a femto BS 1b that forms a relatively small femto cell FC of about several tens of meters is installed in a relatively large macro cell MC. This is because the macro cell MC and the femto cell FC are overlapped with each other, so that signals can easily reach each other between the macro cell MC and the femto cell FC.

  In order to suppress the inter-cell interference, the own cell uses a frequency that is not used in other cells, or limits the magnitude of the power (transmission power) of a signal transmitted from the base station apparatus or terminal apparatus of the own cell. Then, it may be possible to make it difficult for signals to reach other cells. The MAC scheduler described later performs frequency allocation so as to suppress the inter-cell interference. Details of the scheduling function by the MAC scheduler will be described later.

  FIG. 2 shows a structure of an LTE downlink radio frame (DL frame). One DL frame is configured by arranging 10 subframes in the time axis direction (note that FIG. 2 shows a part of one DL frame). One subframe has a length of 14 OFDM symbols (= 1 msec) in the time axis direction.

  Each subframe has a control area in which control information (Control Information) is stored at the head thereof, and thereafter, a PDSCH (Physical Downlink Shared Channel) in which user data is stored is secured.

  A downlink control channel (PDCCH: Physical Downlink Control Channel) including downlink and uplink allocation information and the like is secured in the control area. In addition to the allocation information, the PDCCH includes information on an uplink transmission power limit value, a report instruction for a downlink CQI (Channel Quality Indicator), and the like. Note that the size of the PDCCH changes according to the size of the control information.

  In addition to the PDCCH, a control channel configuration indication channel (PCFICH: Physical Control Indicator Channel) for notifying information on the PDCCH and a hybrid automatic repeat request (HARQ: Hybrid Automatic Repeat) reception request for the PUSCH are included in the control region. A hybrid ARQ indication channel (PHICH: Physical Hybrid-ARQ Indicator Channel) for transmitting a notification of success (ACK: Acknowledgment) and a notification of reception failure (NACK: Negative Acknowledgment) is also assigned.

The PDSCH in which user data and the like are stored is an area that is shared and used by a plurality of terminal apparatuses, and stores control information and the like for each terminal apparatus in addition to user data.
The PDSCH includes a plurality of resource blocks (RBs) that are basic unit areas (minimum units for resource allocation) in data transmission. The resource block has a size of 12 subcarriers in the frequency axis direction and 7 OFDM symbols in the time axis direction.

  When the frequency bandwidth of the DL frame is set to 10 MHz, 601 subcarriers are arranged. Therefore, 50 resource blocks are arranged in the frequency axis direction in one subframe, and the number of resource blocks in the time axis direction in one subframe is two.

  The base station apparatus 1 has a power allocation scheduling function for allocating resource blocks, which are radio resources, to terminal apparatuses and determining a transmission power value for each resource block. Similarly to the DL frame, the LTE uplink radio frame (UL frame) also includes a plurality of resource blocks, and the allocation of the DL frame resource blocks to the terminal apparatus is also performed by the base station apparatus 1. It is determined.

  The downlink and uplink resource block allocations determined by the base station apparatus 1 are stored in the PDCCH as allocation information and transmitted from the base station apparatus 1 to the terminal apparatus 2. The base station apparatus 1 and the terminal apparatus 2 perform communication using resource blocks according to the determined allocation information.

FIG. 3 shows the configuration of the base station apparatus 1. This base station apparatus configuration is suitable as a configuration for the femto BS 1b, but can also be applied to the macro BS 1a.
As illustrated in FIG. 3, the base station apparatus 1 includes a MAC unit 30 that performs processing related to a MAC layer of wireless communication, and a PHY unit 20 that performs processing related to a physical layer (PHY layer) that is a lower layer of the MAC layer. Have.

  In this embodiment, the base station apparatus 1 includes an independent MAC scheduler 10 separately from the MAC unit 30. The MAC scheduler 10 uses the scheduling information to determine which resource block of a plurality of resource blocks is allocated to which terminal, and also determines a transmission power value for each resource block.

The MAC scheduler 10 is connected to the MAC unit 30 and can exchange necessary information with the MAC unit 30.
For example, the MAC scheduler 10 receives, from the MAC unit 30, the Buffer CH of Common CH and Dedicated CH, and the Control Element of the UL subframe.
Further, the MAC scheduler 10 transmits information on the scheduled terminal device to the MAC unit 30.

The MAC scheduler 10 is connected so that information can be exchanged with the PHY unit 20 without using the MAC unit 30.
For example, the MAC scheduler 10 receives TTI indication, RA (Random Access) Request Indication, HARQ feedback indication, SR (Scheduling Request) Indication, DL CQI Indication, UL CQI Indication, UL CQI Indication, UL CQI Indication, UL CQI Indication .

  Further, when the MAC scheduler 10 transmits control information (PDCCH, PCFICH, PHICH) for the next DL subframe and a reception request for the next UL subframe to the PHY unit 20, The data is transmitted directly to the PHY unit 20 without going through the MAC unit 30.

As described above, the MAC scheduler 10 is connected to the MAC unit 30 so as to be able to exchange information, and is also connected to the PHY unit 20 so as to be able to exchange information without going through the MAC unit 30.
When information is exchanged between the MAC scheduler 10 and the PHY unit 20 without going through the MAC unit 30, there is no delay caused by passing through the MAC unit 30, and exchange can be performed quickly. Moreover, the processing load of the MAC unit 30 can be reduced by reducing the amount of information passing through the MAC unit 30.

Above the MAC unit 30, an RLC (Radio Link Control) 40, a PDCP (Packet Data Convergence Protocol) 50, an RRC (Radio Resource Control) 60, and an RRM (Radio Resource Management) 70 are arranged.

  The RRM (radio resource management unit) 70 has functions such as a PHY control 71, a C-PLANE control 72, and a U-PLANE control 73.

Further, the RRM (radio resource management unit) 70 includes a schedule information management unit 74 that generates and manages scheduling information (Schedule Information) to be given to the MAC scheduler 10. The schedule information management unit 74 acquires, generates, manages, and transmits X2 information, QoS information, and CQI information among scheduling information necessary for scheduling.
Further, the RRM 70 can communicate with other base station devices via an X2 interface 75 that is an inter-base station communication interface with other base station devices.

The MAC scheduler 10 is connected so that information can be exchanged with the RRM 70 (schedule information management unit 74) without going through the MAC unit 30.
For example, the MAC scheduler 10 receives, from the RRM 70, Cell Config information, UE (User Equipment) configuration information, and LCH (Logical Channel) configuration information.

The Cell Config information is received by the MAC scheduler 10 from the RRM 70 at the time of cell creation.
The Cell Config information includes information such as Bandwidth information, UL Subband information, RA config, SRS (Sounding Reference Signal) config, and System Information Config.

The UE config information is received by the MAC scheduler 10 from the RRM 70 when the terminal device 2 establishes the RRC connection.
The UE config information, RNTI (Radio Network Temporary Identifier), DRX (Discontinuous Reception) config, TimeAlignmentTimer, measurement Gap Pattern, Semi Persistent Scheduling Config, SR config, CQI config, and includes information such as HARQ config.

The LCH config information is received by the MAC scheduler 10 from the RRM 70 when a radio bearer of the terminal device is established.
The LCH config information includes information such as Logical CH Group Config and QoS (Quality of Service) information.

  The QoS information includes QCI (QoS Class Indicator), GBR (Guaranted bit rate), and MBR (Maximum Bit Rate).

  Regarding the information received by the MAC scheduler 10 from the RRM 70, if necessary, refer to 3GPP TS36.331 v8.50 6.3.2 “Radio Resource Control information element”.

  Further, the MAC scheduler 10 can directly transmit information indicating the allocation result to the RRM 70 without using the MAC unit 30.

As described above, the MAC scheduler 10 is connected to the RRM (radio resource management unit) 70 so as to exchange information without using the MAC unit 30.
When information is exchanged between the MAC scheduler 10 and the RRM 70 without going through the MAC unit 30, there is no delay caused by going through the MAC unit 30, and exchange can be performed quickly. Moreover, the processing load of the MAC unit 30 can be reduced by reducing the amount of information passing through the MAC unit 30.

  That is, as shown by an arrow A in FIG. 4, when information (scheduling information) is exchanged between the MAC scheduler 10 and the RRM 70 via the MAC unit 30, the exchanged information includes the MAC unit 30 and It takes time to pass through other functional blocks. Further, the processing load on the MAC unit 30 and the like increases due to the processing of passing information.

On the other hand, as shown by an arrow B in FIG. 4, when information (scheduling information) is directly exchanged between the MAC scheduler 10 and the RRM 70 without using the MAC unit 30, it can be quickly performed. In addition, the processing load on the MAC unit 30 can be reduced. As a result, the processing processor constituting the MAC unit 30 may be relatively slow, and cost can be reduced.

In addition, in the configuration of FIG. 4, when the scheduling information (Schedule Information) is not directly exchanged between the MAC scheduler 10 and the RRM 70, it is necessary to have the scheduling information in both the RRM 70 and the MAC unit 30. is there. In this case, exclusive control of scheduling information in each of the RRM 70 and the MAC unit 30 is necessary, and overhead related to exclusive control occurs.
Therefore, it is necessary to increase the speed of the processing processor that constitutes the MAC unit 30, but this can be avoided by directly exchanging between the MAC scheduler 10 and the RRM 70.

The MAC scheduler 10 includes a scheduler main body 11 that determines which resource block is allocated to which terminal among a plurality of resource blocks and determines a transmission power value for each resource block.
The scheduler body 11 is configured to perform scheduling according to a predetermined scheduling algorithm.

As shown in FIG. 5, the scheduler main body 11 receives terminal-specific priority α _n , terminal-specific specified throughput β _n , CQI information γ _kn , and power limit information P _n as scheduling information.
Then, the scheduler body 11 outputs the number of PDCCH symbols, the resource block allocation information S _k to each terminal device, and the transmission power value p _kn of each resource block as a result of scheduling.

Note that k is the number of the terminal device (user), and k = 1 to K (K is the number of terminal devices in the own cell). S _k represents a set of resource blocks allocated to the k-th terminal device. N is a resource block number, and n = 1 to N (N is the total number of resource blocks). p _kn indicates the transmission power value of the n-th resource block among the resource blocks allocated to the k-th terminal device.

The scheduling result (number of PDCCH symbols, S _k , p _kn ) output from the scheduler main body 11 is output to the adaptive modulation control unit 12.
The adaptive modulation control unit 12 that has received S _k and p _kn from the scheduler main body 11 adaptively _applies a modulation scheme (including a coding rate) to each terminal device based on the information S _k and p _kn. To decide.

  The MAC scheduler 10 transmits information indicating the allocation and transmission power determined by the scheduler main body 11 and the modulation scheme determined by the adaptive modulation control unit 12 to the PHY unit 20 without using the MAC unit 30. To do.

  Further, the data stored in the data buffer 31 of the MAC unit 30 is given to the PHY unit 20 for modulation or the like. The data buffer 31 receives and stores data to be transmitted from the upper layer, and sends necessary data to the PHY unit 20 according to the resource block allocation result.

  In order to control the data transmission timing from the data buffer 31 to the PHY unit 20, the MAC scheduler 10 gives the MAC unit 30 information on the terminal device to which the resource block is allocated as a scheduling result. When the MAC unit 30 recognizes that a resource block has been assigned to a terminal device to which data is to be transmitted, the MAC unit 30 transmits the data from the data buffer 31 to the PHY unit 20.

  The PHY unit 20 actually performs resource block allocation, transmission power adjustment, and data modulation on the data provided from the data buffer 31 of the MAC unit 30 according to information indicating the allocation result of the MAC scheduler 10 and the like. .

As described above, the MAC unit 30 only needs to send data from the data buffer 31 based on the scheduling result in the MAC scheduler 10 and does not need to perform scheduling itself, so the processing load is reduced.
In addition, since the information indicating the allocation and transmission power determined by the scheduler main body 11 and the modulation scheme determined by the adaptive modulation control unit 12 is given to the PHY unit 20 without going through the MAC unit 30, this point Also, the processing load on the MAC unit 30 is reduced.

Further, the scheduling results such as assignment information _{S k} and the transmission power _{p kn} determined by the scheduler body 11 from the MAC scheduler 10, not via the MAC unit 30 is provided to RRM70.
The scheduling results S _k and p _kn received by the RRM 70 and other information that can be used for interference suppression control in other base station devices are transmitted to the other base station devices 1 via the X2 interface that is a communication interface between base stations. Sent.

Other base station apparatuses that have received the scheduling result S _k , p _kn and the other information via the X2 interface use resource blocks that do not cause inter-cell interference using the received information. Interference suppression control such as suppressing transmission power of resource blocks that may cause inter-cell interference when used.

In order for the other base station apparatus to appropriately perform interference suppression control, it is preferable that the scheduling results S _k , p _kn and the other information are sent as quickly as possible. In the present embodiment, the scheduling results S _k and p _kn are directly given from the MAC scheduler 10 to the RRM 70 without going through the MAC unit 30, so that information can be sent to other bases more quickly than when going through the MAC unit 30. It can be transmitted to the station device.

Now, the scheduler body 11 has a priority α _k (k: 1 to K) for each terminal device, a specified throughput β _k (k: 1 to K) for each terminal device, and a resource block for each terminal device. Using information (scheduling information) such as a communication quality value γ _kn (k: 1 to K, n: 1 to N), an optimal allocation of resource blocks is determined.

The scheduler body 11 acquires the priority α _k for each terminal device from a QoS (Quality of Service) control unit 14 provided in the MAC scheduler 10. The QoS control unit 14 generates the priority α _k for each terminal device based on the application information acquired from the upper layer and the data delay information acquired from the data buffer 31 of the MAC unit 30. The priority α _k determines the number of resource blocks allocated to the terminal device. That is, the scheduler body portion 11, the value is large terminal priority alpha _k, allocate more resource blocks, the value is smaller terminal device priority alpha _k, to allocate less resource blocks Become.

The scheduler body 11 also acquires the specified throughput β _{k for} each terminal device from the QoS control unit 14. The specified throughput β _k is a specified value of the throughput required for each terminal device, and the QoS control unit 14 determines the specified throughput β based on the application information acquired from the upper layer and the data delay information acquired from the data buffer 31. _k is generated.

The QoS control unit 14 mainly obtains information for generating the priority α _k and the specified throughput β _k (the information is also “scheduling information”) from the MAC unit 30.

The scheduler body 11 acquires the communication quality value γ _kn for each resource block for each terminal device from the CQI information controller 15 provided in the MAC scheduler 10. The communication quality value γ _kn here is CQI. The CQI information control unit 15 generates a communication quality value γ _kn based on CQI (Channel Quality Indicator) information indicating the communication quality of each resource block in uplink and downlink. The uplink CQI can be acquired by measurement by the base station apparatus 1 itself, and the downlink CQI can be acquired by the base station apparatus receiving the measurement by the terminal apparatus. The CQI can be generated based on, for example, SINR (Signal to Interference and Noise power Ratio).

  If the communication quality is good, the communication speed can be increased, and even when the same number of resource blocks are allocated, more data can be transmitted than when the communication quality is bad.

The CQI information control unit transmits the uplink and downlink CQIs of its own cell as information for generating the communication quality value γ _kn (such information is also “scheduling information”) without passing through the MAC unit 30. Get from 20.

The scheduler body 11 acquires a transmission power limit value (power limit information) P _n (n: 1 to N) for each resource block from the power limit control unit 16 provided in the MAC scheduler 10. The transmission power limit value P _n here defines the upper limit value of the transmission power of the signal transmitted from the base station apparatus itself or the terminal apparatus for each resource block (the lower limit value may also be defined). .

  The limitation on the transmission power is to prevent interference with other cells (the base station apparatus or terminal apparatus). That is, if a resource block used in another cell is also used in the own cell, the signal transmitted from the base station device or terminal device of the own cell may become an interference signal in the other cell. Should be kept low. On the other hand, for resource blocks that are not used in other cells, the transmission power can be increased to increase the throughput.

For this reason, it is desirable to make the transmission power different according to the usage status of the resource block in another cell in order to perform efficient communication while preventing interference. However, the transmission power value p _kn in each resource block is not determined only from the viewpoint of interference suppression. Therefore, the power limit control unit 16 of the present embodiment does not determine the actual transmission power value p _kn of each resource block, but suppresses the actual transmission power value p _kn to a size that does not cause interference to other cells. The upper limit value (transmission power limit value) P _n of the transmission power value is set for each resource block.

Then, the scheduler body portion 11, within the range of the transmission power limit value (upper limit value) P _n, adjusts the transmission power value p _kn for each resource block, including the adjustment of the transmission power value p _kn for each resource block Perform resource block allocation.

In order to generate a transmission power limit value (power limit information) P _n for each resource block, the power limit control unit 16 generates resource blocks from the CQI information control unit 15, the X2 information control unit 17, the PHY measurement information control unit 18, and the like. Interference control information (interference power information) for each resource block is acquired, and a transmission power limit value P _n for each resource block is determined based on the acquired interference control information.

In the present embodiment, the interference control information includes interference power information when interference is received from other cells and interference power information when interference is given to other cells. Any interference power information can be used to determine the transmission power limit value P _n for each resource block.

When there is interference from other cells, signals from other cells are likely to reach. Therefore, when a resource block with interference is used in its own cell, there is a risk of interference with other cells.
For this reason, from the viewpoint of not hindering communication of other cells (macro cells), the transmission power of the resource block should be small in the own cell.

  Also, for resource blocks with interference to other cells, the transmission power of the resource blocks should be small in the own cell from the viewpoint of not hindering communication of other cells (macro cells).

The PHY unit 20 of the base station apparatus 1 pauses communication in its own cell, sniffs communication between the base station apparatus 1a and the terminal apparatus 2a in another cell (macro cell), and resources of signals from other cells A measurement unit 21 that measures received power for each block is provided. The magnitude of the received power of the signal from the other cell indicates the magnitude of the interfered power.
Therefore, the PHY measurement information control unit 18 acquires the received power for each resource block of the signal from the other cell from the measurement unit 21 without using the MAC unit 30, and obtains the interfered power information for each resource block. The interference power information (scheduling information) is generated and given to the power limit control unit 16.

  Further, the interfered power from another cell may be measured by the terminal device 1b of the own cell, and the base station device 1 may receive it as a CQI report. The CQI information control unit 15 acquires the CQI report received from the terminal device 1b from the PHY unit 20 without using the MAC unit 30, and generates the interfered power information for each resource block. Information is given to the power limit control unit 16.

  Further, the MAC scheduler 10 according to the present embodiment forms not only the interfered power information from other cells but also the interfered power information (scheduling information) measured in other cells (macrocells) to form the other cells. From the base station apparatus (macro BS) of the network via the X2 interface.

The interfered power measured in another cell (macro cell) indicates the magnitude of the interference power from the own cell (femto cell).
Therefore, the schedule information management unit 74 of the RRM 70 acquires the interfered power information from another base station device via the X2 interface, and transmits it to the X2 information control unit 17 of the MAC scheduler 10 without going through the MAC unit 30. To do.
The X2 information control unit 17 provides the interference power information indicating the magnitude of the interference power to the other base station apparatus (macro BS) based on the magnitude of the interfered power measured in the other cell (macro cell). The interference power information (scheduling information) is generated and given to the power limit control unit 16.

  Note that the CQI information control unit 15 and the PHY measurement information control unit 18 provide the interfered power information of the own cell to the RRM 70 (the schedule information management unit 74) without using the MAC unit 30. The RRM 70 transmits the interfered power information of the own cell to another base station apparatus via the X2 interface. The other base station apparatus can perform scheduling using the received interfered information as interference power information for the own cell.

The power limit control unit 16 suppresses the transmission power limit value (upper limit value) _Pn to be lower as the interference power indicated by the interfered power information and / or the interfered power information increases for each resource block. higher power is low, transmission power limit value as (upper limit) P _n becomes large, the transmission power limit value for each resource block (upper limit) determining P _n. The transmission power limit value P _n is determined based on the interference power information so that the transmission power of the own cell falls within a magnitude that does not interfere with other cells.

  As shown in FIG. 5, the scheduler body 11 of this embodiment includes a control area scheduler 11a, a VoIP scheduler (voice / video scheduler) 11b, an HRQ scheduler (retransmission scheduler) 11c, and a data information scheduler 11d. .

The control area scheduler 11a is for securing a control area for storing control information commonly given to each terminal apparatus.
Each of the VoIP scheduler 11b, HRQ scheduler (retransmission scheduler) 11c, and data information scheduler 11d secures an area for storing user data addressed to each terminal device and performs resource block allocation.

The VoIP scheduler 11b, the HRQ scheduler (retransmission scheduler) 11c, and the data information scheduler 11d all perform scheduling using the transmission power limit value _Pn . On the other hand, the control area scheduler 11a does not use the transmission power limit value _Pn .

  FIG. 6 shows the data information scheduler 11d. The data information scheduler 11d determines resource block allocation to each terminal device and transmission power for each resource block so as to maximize the sum of weighted throughputs according to QoS information (throughput optimization).

More specifically, the data information scheduler 11d maximizes the value of the evaluation function shown in FIG. 6 (the sum of the weighted throughputs) under the constraint conditions 1 to 3 shown in FIG. The resource block allocation S _k to the terminal device and the transmission power value p _kn for each resource block are adjusted. The scheduler 11d can solve the evaluation function of FIG. 6 as a convex linear programming problem. Then, S _k and p _kn when the evaluation function is maximized are output from the scheduler 11d.

Constraint 1 in FIG. 6 is to prevent the total sum of transmission power p _kn for each resource block from exceeding a prescribed maximum total power P _tot . The prescribed maximum total power P _tot is the maximum value of the power that can be actually output in the PHY unit 20, and transmission with power exceeding this is impossible.

The constraint condition 2 in FIG. 6 is that when a certain resource block n is assigned to a certain terminal device (user) k, the transmission power value p _kn of the resource block n is the transmission power limit value of the resource block n. (Upper limit value) This is intended to be within the range defined by _Pn . By the transmission power value p _kn does not exceed the transmission power limit value (upper limit value) P _n, it is possible to set an appropriate transmission power value p _kn can prevent interference to other cells for each resource block .

Constraint condition 3 in FIG. 6 is that when a certain terminal device (user) k ₀ uses a certain resource block n, the resource for other terminal device (user) k (≠ k ₀ ) This is for not assigning block n. That is, when a certain terminal device (user) k ₀ uses a certain resource block n, the transmission power of the resource block becomes larger than 0. At that time, another terminal device (user) k (≠ k ₀ ), “0” is set as the transmission power p _kn of the resource block n. That is, the resource block n is not assigned to another terminal device (user) k (≠ k ₀ ).

  According to the evaluation function of FIG. 6, each terminal apparatus is assigned a resource block with a good communication quality value (CQI), and thus interference from other cells can be avoided. In addition, since the transmission power restriction is made in resource block units by the constraint condition 2 in FIG. 6, it is possible to prevent interference with other cells.

FIG. 7 shows the VoIP scheduler 11b. The HARQ scheduler 11c has the same configuration.
The VoIP scheduler 11b has a transmission power value out of those in which the throughput of the terminal device (user) k (the sum of the throughputs in each resource block allocated to the terminal device) is the specified throughput β _k (or is equal to or larger than β _k ). Resource block allocation to each terminal device and transmission power for each resource block are determined so that p _kn is minimized (power optimization).

More specifically, the VoIP scheduler 11b minimizes the value of the evaluation function shown in FIG. 7 (the sum of the transmission power p _kn for each resource block) under the constraint conditions 1 to 3 shown in FIG. The resource block allocation S _k to each terminal device and the transmission power value p _kn for each resource block are adjusted. The scheduler 11b can solve the evaluation function of FIG. 7 as a convex nonlinear programming problem. Then, S _k and p _kn when the evaluation function is minimized are output from the scheduler 11b.

Constraint 1 in FIG. 7 is that the throughput of the terminal device (user) k (the sum of the throughputs in each resource block allocated to the terminal device) is the prescribed throughput β _{k for} each terminal device k (or β _k or more). Is). In VoIP data, it is more important to always ensure the minimum throughput (stipulated throughput) for a smooth call rather than to increase the throughput as much as possible. In this case, it is more efficient to reduce the transmission power after securing the specified throughput β _k than to maximize the throughput.

The constraint condition 2 in FIG. 7 is the same as the constraint condition 2 in FIG. With this restriction condition 2, the transmission power value p _kn does not exceed the transmission power limit value (upper limit value) P _n and an appropriate transmission power value p _kn that can prevent interference with other cells can be set for each resource block. it can.
Further, the constraint condition 3 in FIG. 7 is the same as the constraint condition 3 in FIG.

  The allocation determined by the VoIP scheduler 11b is validated for several frames by Semi-Persistent Scheduling. The remaining resource blocks other than the resource blocks reserved for VoIP data by the VoIP scheduler 11b are allocated for other user data.

Returning to FIG. 5, each of the schedulers 11 a to 11 d included in the scheduler 11 will be described.
First, the control area scheduler 11a reserves a control area (PDCCH) in which control information given in common to all terminal apparatuses is stored in a subframe. Then, the control region scheduler 11a outputs the number of symbols secured as the control region (PDCCH). The control area is secured by the control area scheduler 11a at a period of several tens of msec (tens of subframe periods). That is, the once secured control area is fixed over a plurality of subframes.
In addition, the control area scheduler 11a notifies the VoIP scheduler 11b of information indicating areas other than the control area of the radio frame as information on areas that can be used by the other schedulers 11b to 11d.

Based on the notified usable area information, the VoIP scheduler 11b recognizes a remaining area that is not secured as a control area, and stores some of the resource blocks included in the remaining area as VoIP data. Secure as an area. The VoIP scheduler 11b determines a resource block (and its transmission power) secured as a VoIP area using the evaluation function described above. Then, the VoIP scheduler 11b outputs information of S _k and p _kn for VoIP data.

The reservation of the VoIP area by the VoIP scheduler 11b is also performed with a period of several tens of msec (tens of subframe periods). That is, the VoIP area once secured is fixed over a plurality of subframes, and a stable call is possible.
In addition, since the area for securing the VoIP data is preferentially secured prior to other user data, a stable call is possible from this point.

  The VoIP scheduler 11b uses the HARQ scheduler 11c as information indicating other areas that are not secured as either the control area or the VoIP area in the radio frame as information on areas that can be used by the other schedulers 11c and 11d. Notify

Based on the notified usable area information, the HARQ scheduler (retransmission scheduler) 11c recognizes the remaining area that is not secured as either the control area or the VoIP area, and includes resource blocks included in the remaining area Are reserved as retransmission data areas for storing retransmission data. Similarly to the VoIP scheduler 11b, the HARQ scheduler 11c also determines a resource block (and its transmission power) reserved as a HARQ data area. Then, the HARQ scheduler 11c outputs information on S _k and p _kn for HARQ data.

  The HARQ data area is secured by the HARQ scheduler 11c in 1 msec cycle (1 subframe cycle). Since the data for retransmission is highly urgent in transmission, the data for retransmission can be reliably transmitted by determining the assignment with priority over other user data.

  In the radio frame, the HARQ scheduler 11c uses the information indicating other areas that are not secured as any of the control area, the VoIP area, and the retransmission data area as information on the area that can be used by the data information scheduler 11d. , Notify the data information scheduler 11d.

Based on the notified usable area information, the data information scheduler 11d recognizes a remaining area that is not secured as any of the control area, the VoIP area, and the retransmission data area, and includes resources included in the remaining area Some of the blocks are reserved as general data areas for storing user data other than VoIP and retransmission data.
The data information scheduler 11d determines a resource block (and its transmission power) secured as a general data area using the evaluation function described above. Then, the data information scheduler 11d outputs information on S _k and p _kn for general data.
Note that the general data area is also secured by the data information scheduler 11d in a 1 msec cycle (1 subframe cycle).

As described above, by assigning resource blocks in areas other than the control area in the order of VoIP data, retransmission data, and general data, assignment according to the priority of data is possible.
In the scheduler 11 of this embodiment, allocation control and power control for user data other than VoIP data are performed every 1 msec (1 subframe), but may be performed every several subframes.

The scheduling results (S _k , p _kn ) and the like obtained as described above are given to the PHY unit 20 without going through the MAC unit 30, and are given to the RRM 70 without going through the MAC unit 30. Via the base station apparatus.

  FIG. 8 shows an example of power allocation when a base station apparatus having the above-described function is adopted as the femto BS 1b to prevent interference with an adjacent macro cell. A macro cell user (terminal device) B in FIG. 8 is a cell edge user (a user existing in the vicinity of the femto cell), and a signal in the femto cell is likely to interfere with the user B.

In this case, the macro BS 1a transmits the scheduling result (S _k , p _kn ) in the own cell and the interfered power information received from the femto cell (interference control information) as an instruction to suppress power to the femto BS 1b via the X2 interface. Send.

The femto BS 1b that receives the instruction from the macro BS 1a generates interference power information for each resource block in the X2 information control unit 17.
Further, the power limit control unit 16 controls the power limit for the same resource block (resource block allocated to the user E in the femto cell) as the resource block allocated to the user B of the macro cell based on the interference power information. Information Pn is generated.
The scheduler 11 decreases the transmission power value p _kn of the resource block allocated to the user E based on the power limit information Pn. This prevents interference from the femtocell to the macrocell.

Note that the transmission power value p _kn may be small even in the case of not causing interference to the macro cell, such as the user F of the femto cell. This is because, as is apparent from the evaluation function of FIG. 6, depending on the state of the communication channel (communication quality; CQI), the transmission power of the resource block may be kept small.

According to the present embodiment, the femto BS 1b that has received the instruction from the macro BS 1a can quickly provide the information included in the instruction directly from the RRM 70 to the MAC scheduler 10 without using the MAC unit 30. Therefore, the femto BS 1b can quickly perform scheduling reflecting the resource block usage status of the macro BS 1a.
Moreover, since the femto BS 1b can quickly transmit its own scheduling results to the macro BS 1a and other femto BSs 1b via the X2 interface, it is possible to quickly respond to the other BSs 1a and 1b. It becomes.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Base station apparatus 1a Macro base station apparatus 1b Femto base station apparatus 2a Macro terminal apparatus 2b Femto terminal apparatus 10 MAC scheduler 11 Scheduler main-body part 11a Control area scheduler 11b VoIP scheduler 11c HARQ scheduler 11d Data information scheduler 16 Power restriction control part 20 PHY Unit 30 MAC unit 70 RRM (radio resource management unit)
MC Macrocell FC Femtocell

Claims (10)

A MAC unit for processing the MAC layer of wireless communication;
A PHY unit that performs processing of a PHY layer that is a lower layer of the MAC layer;
A scheduler that performs scheduling to determine radio resource allocation;
A radio resource management unit for managing radio resources;
With
The MAC unit includes a data buffer that receives and stores data to be transmitted from an upper layer, and is configured to send the data buffer data to the PHY unit;
The scheduler is configured to give a radio resource allocation result to the MAC unit;
The MAC unit is configured to send the data buffer data to the PHY unit based on a radio resource allocation result by the scheduler,
The scheduler is connected to the radio resource management unit so that the scheduling information required for performing the scheduling can be acquired from the radio resource management unit without going through the MAC unit. A characteristic base station apparatus. The radio resource management unit is configured to exchange information between base station devices via a base station communication interface,
The scheduler, the radio resource management unit via the communications interface between the base station information acquired from the other base station apparatus, base station apparatus according to claim 1, wherein the obtaining, as the scheduling information. The scheduling information includes interference control information used for interference control for suppressing inter-cell interference,
The base station apparatus according to claim 2 , wherein the scheduler performs the scheduling using the interference control information so as to suppress inter-cell interference. The base station apparatus according to claim 1 or 2 , wherein the scheduler is configured to provide allocation information indicating a radio resource allocation result to the radio resource management unit without passing through the MAC unit. The base station apparatus according to claim 4, wherein the radio resource management unit is configured to transmit the allocation information acquired from the scheduler to another base station apparatus via an inter-base station communication interface. The scheduler, not via the MAC unit, front Symbol P HY portion so as to be able to provide information, the base station according to any one of claims 1 to 5, which is connected to the PHY unit apparatus. The base station apparatus according to claim 6 , wherein the scheduler is configured to provide allocation information indicating a radio resource allocation result to the PHY unit without passing through the MAC unit. The scheduler, not via the MAC unit, the so retrieve information from the PHY unit, the base station apparatus according to any one of claims 1 to 7, which is connected to the PHY unit. The PHY unit is configured to generate scheduling information required for performing the scheduling from a received signal;
The base station apparatus according to claim 8 , wherein the scheduler is configured to acquire the scheduling information from the PHY unit without passing through the MAC unit. A MAC unit for processing the MAC layer of wireless communication;
A PHY unit that performs processing of a PHY layer that is a lower layer of the MAC layer;
A scheduler that performs scheduling to determine radio resource allocation;
A radio resource management unit for managing radio resources;
With
The MAC unit includes a data buffer that receives and stores data to be transmitted from an upper layer, and is configured to send the data buffer data to the PHY unit;
The scheduler is configured to give a radio resource allocation result to the MAC unit;
The MAC unit is configured to send the data buffer data to the PHY unit based on a radio resource allocation result by the scheduler,
The scheduler is connected to the radio resource management unit so as to be able to give allocation information indicating a radio resource allocation result to the radio resource management unit without going through the MAC unit. Base station equipment.

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