JP5335748B2 - Base station apparatus and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base station device for preventing or reducing the deterioration of reception quality in an unregistered terminal (a non-closed subscriber group terminal) existing within the coverage area of a base station (a closed subscriber group (CSG) base station) communicating with registered terminals (CSG terminals). <P>SOLUTION: A base station device 10 for communicating only with registered terminals includes: an unregistered terminal existence determination section (a non-CSG terminal detection section 110) for determining whether an unregistered terminal (a non-CSG terminal 30) exists within the coverage area of a self station 10; an antenna transmission mode determination section 120 for determining the antenna transmission mode of the self station 10 on the basis of a determination result in the unregistered terminal existence determination section; a scheduler mode determination section 130 for determining the scheduler mode of the self station on the basis of the determination result in the unregistered terminal existence determination section; and an orthogonal frequency division multiplexing (OFDM) symbol number determination section 140 for determining the number of OFDM symbols to be used in a physical downlink control channel (PDCCH) for announcing radio resource allocation information on the basis of the determination result in the unregistered terminal existence determination section. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a base station apparatus and a program.

  Currently, standardization organizations for wireless interfaces such as 3GPP (3rd Generation Partnership Project) are aiming to further improve the frequency utilization efficiency of third generation systems such as W-CDMA. Standardization of the 3rd generation successor system is progressing. The downlink radio access scheme in LTE is OFDMA (Orthogonal Frequency Division Multiple Access). In OFDMA, the system bandwidth is divided into a plurality of subcarrier groups, and data channels are allocated to different terminals for each subcarrier group. In OFDMA, the configuration of subcarrier groups and allocated terminals are changed with time. Therefore, in the OFDMA system, a physical channel can be flexibly allocated using a two-dimensional radio resource composed of a frequency component and a time component (see, for example, Non-Patent Documents 1 and 2).

In LTE downlink, a channel quality measurement signal called RS (Reference Signal) is indispensable for channel quality estimation.
Also, in LTE, a physical control channel for notifying radio resource allocation information called PDCCH (Physical Downlink Control Channel) is used to notify time-varying uplink and downlink data channel allocation information to a terminal.
Also, in the LTE downlink, PDCCH uses a physical control channel for reporting PDCCH OFDM symbol number information (information indicating the number of OFDM symbols used by PDCCH) called PCFICH (Physical Control Format Indicator Channel). Informs the terminal of the number of OFDM symbols to be used. The LTE downlink subframe is composed of 14 OFDM symbols × the number of subcarriers in the band, and the PDCCH region used for PDCCH allocation is a maximum of 3 OFDM symbols from the top OFDM symbol.

The arrangement of radio resources of RS, PCFICH, and PDCCH in the LTE downlink will be described using FIG. FIG. 4 is an explanatory diagram for explaining RE and REG.
(REG (Resource Element Group) definition)
1 REG = 1 OFDM symbol × 4 Subcarrier is defined. In LTE, since 1 OFDM symbol × 1 subcarrier is defined as RE (Resource Element), 1REG = 4RE as shown in FIG.

  The LTE downlink control channel occupies radio resources in units of REGs. Hereinafter, REG is written using (x, y). Where x is the lowest reference (inclusive reference signal) in the REG, and y is the OFDM symbol ID.

(RS radio resource allocation)
In the LTE downlink, RS radio resources are determined depending on the number of antenna ports. Specifically, RS radio resources are determined according to the following equation (1). In addition, in FIG. 4, the example of RS arrangement | positioning in the base station of the number of antennas = 2 and Cell ID = 0 is shown.

  As shown in FIG. 4 and the above formulas (1) to (3), in the case of two antennas, the RS arrangement is a maximum of three patterns. That is, there is a possibility of overlapping with the RS arrangement of adjacent base stations.

(PCFICH wireless resource allocation)
The PCFICH radio resource is determined according to the following equation (4) using 4REG with OFDM symbol ID = 0.

  In the case of a multi-antenna, the PCFICH is transmitted using the PCFICH transmission diversity mode using the same radio resource of each antenna port. For example, when cell ID = 0, 4REGs of (0, 0) (150, 0) (300, 0) (450, 0) are allocated to the PCFICH. When cell ID = 1, 4REGs of (6, 0) (156, 0) (306, 0) (456, 0) are allocated to the PCFICH. When cell ID = 25, 4REG of (150, 0) (300, 0) (450, 0) (0, 0) is allocated to PCFICH.

(PDCCH radio resource allocation)
For the PDCCH of each terminal, radio resources are used in units of CCE (Control Channel Element). According to the specification of LTE, the radio resource of 1CCE, 2CCE, 4CCE or 8CCE is used for PDCCH. The CCE is composed of 9REG.
Mapping with the REGs constituting the CCE starts from the REG represented by (0, 0), and y is incremented ⇒ x is incremented in order, and REGs not assigned to other physical control channels are sequentially selected to construct the CCE. To do.

  By the way, there is currently a technology for improving the wireless quality of indoor / outdoor local areas (for example, high-rise buildings, residential indoors, underground shopping streets) where large-volume traffic is concentrated and mitigating traffic in conventional macro areas. Attention has been paid. That is, a femto base station (hereinafter referred to as a “femto cell”) having a lower transmission power than a base station (hereinafter referred to as “macro base station”) that forms the macro area in the macro area. ) To interpolate the macro area. FIG. 5 is a schematic diagram of a heterogeneous radio access network constructed from a macro cell and a femto cell.

  The femto base stations can be classified into CSG (Closed Subscriber Group) femto base stations and non-CSG femto base stations. The CSG femto base station is used only by registered terminals (hereinafter referred to as “CSG terminals” or “registered terminals”) registered in advance with the own station, and is not registered with the own station (hereinafter referred to as “CSG terminal”) This is a femto base station that is not used for “non-CSG terminal” or “unregistered terminal”. That is, the CSG femto base station opens when the CSG terminal is located in its own coverage area (femtocell), and does not open when the non-CSG terminal is located in its own coverage area. On the other hand, the non-CSG femto base station is a femto base station that does not particularly limit terminals to be opened. Note that a CSG femto base station is often applied to a femto base station installed in a private house. This is because, in WiFi in a private house, the user normally sets security and restricts the use of others. Hereinafter, the CSG femto base station is referred to as a CSG base station.

3GPP, TS 36.211 V9.1.0, “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 9),” March 2010. 3GPP, TS 36.213 V9.1.0, “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures (Release 9),” March 2010.

  However, when the area is expanded by the CSG base station, the reception quality of the physical control channel of the non-CSG terminal that is unregistered with respect to the CSG base station located in the coverage area of a certain CSG base station is stronger than that of the CSG base station. There is a problem that it is lowered by interference. That is, if there is an unregistered terminal (non-CSG terminal) in the coverage area of a small base station (CSG base station) installed to communicate with a registered terminal (CSG terminal), the unregistered terminal There is a problem that the reception quality of the physical control channel deteriorates due to strong interference of the small base station.

Specifically, the following problems occur with respect to RS, PCFICH, and PDCCH.
(Reduction and impact of RS reception quality)
When a non-CSG terminal that cannot access a CSG base station approaches the CSG base station, the non-CSG terminal cannot receive an RS from the macro base station due to strong interference from the CSG base station. Radio link failure may occur.
(Decrease and impact of PCFICH reception quality)
When a non-CSG terminal that cannot access a CSG base station approaches the CSG base station, the non-CSG terminal cannot receive PCFICH from the macro base station due to strong interference from the CSG base station. Information may not be decrypted.
(Degradation and impact of PDCCH reception quality)
When a non-CSG terminal that cannot access a certain CSG base station approaches the CSG base station, the non-CSG terminal cannot receive the PDCCH from the macro base station due to strong interference from the CSG base station. Information may not be decrypted.

  The present invention has been made in view of such circumstances, and an unregistered terminal is included in the coverage area of a small-scale base station (CSG base station) installed to communicate with a registered terminal (CSG terminal). An object of the present invention is to provide a base station apparatus or the like that can prevent or reduce a decrease in reception quality of a physical control channel of an unregistered terminal when (non-CSG terminal) exists.

  In order to solve the above problem, a base station apparatus according to an aspect of the present invention is a base station apparatus (CSG base station apparatus) that communicates only with a registered terminal (CSG terminal) registered in advance. Based on the determination result by the unregistered terminal presence / absence determining unit that determines whether or not an unregistered terminal (non-CSG terminal) that is a terminal exists in the coverage area of the own station, An antenna transmission mode determining unit that determines an antenna transmission mode of the station; a scheduler mode determining unit that determines a scheduler mode of the local station based on a determination result by the unregistered terminal presence determining unit; and the unregistered terminal presence determining unit An OFDM symbol that determines the number of OFDM symbols used by the physical control channel (PDCCH) that notifies the radio resource allocation information based on the determination result of Characterized in that it comprises a number determination unit.

  In the base station apparatus, when the antenna transmission mode determination unit determines that there is no unregistered terminal in the coverage area of the own station by the unregistered terminal existence determination unit, the number of antennas installed in the own station If the non-registered terminal existence determination unit determines that there is an unregistered terminal in the coverage area of the local station, another base station (macro) with which the unregistered terminal communicates is determined. The antenna transmission mode may be determined according to the presence / absence of information related to the number of antennas of the base station).

  In the base station apparatus, when the antenna transmission mode determination unit determines that there is an unregistered terminal in the coverage area of the local station by the unregistered terminal existence determination unit, the antenna transmission mode determination unit determines the number of antennas of the other base station. When there is no such information, the antenna transmission mode is determined to be a single antenna transmission mode, and when there is information related to the number of antennas of the other base station, the number of antennas of the other base station and the antenna of the own station The antenna transmission mode may be determined based on the relationship with the number.

  In the base station apparatus, when the antenna transmission mode determination unit determines the antenna transmission mode to be a single antenna transmission mode, a Wideband CQI (Wideband C) fed back to the local station as an antenna port used in the single antenna transmission mode. The one with the better average value of (Channel quality) may be selected.

  In the base station apparatus, the scheduler mode determination unit determines the scheduler mode as a dynamic scheduler mode when the unregistered terminal existence determination unit determines that there is no unregistered terminal in the coverage area of the local station. When the unregistered terminal presence / absence determining unit determines that there is an unregistered terminal in the coverage area of the own station, the scheduler mode may be determined as a semi-persistent scheduler mode.

  In the base station apparatus, the scheduler mode determination unit switches the scheduler mode from the semi-persistent scheduler mode to the dynamic scheduler mode periodically or in an event-driven manner when the scheduler mode is a semi-persistent scheduler. You may do it.

  In the base station apparatus, when the unregistered terminal existence determination unit determines that there is no unregistered terminal in the coverage area of the own station, the OFDM symbol number determination unit sets the OFDM symbol number to a value other than zero. If the unregistered terminal presence / absence determining unit determines that there is an unregistered terminal in the coverage area of the own station, the number of OFDM symbols may be determined to be zero.

  In the base station apparatus, the OFDM symbol number determination unit may switch the number of OFDM symbols from 0 to a value other than 0 periodically or event-driven when the number of OFDM symbols is 0. .

  In order to solve the above-described problem, a program according to another aspect of the present invention includes a computer of a base station apparatus that communicates with only a registered terminal registered in advance, and an unregistered terminal that is a terminal other than the registered terminal. A determination step for determining whether or not the mobile station exists within the coverage area, an antenna transmission mode determination step for determining the antenna transmission mode of the own station based on a determination result by the determination step, and a determination result by the determination step Based on the scheduler mode determining step for determining the scheduler mode of the local station based on the determination result of the determining step, the number of OFDM symbols for determining the number of OFDM symbols used by the physical control channel for notifying the radio resource allocation information is determined. And executing a step.

  According to the present invention, when an unregistered terminal (non-CSG terminal) exists in the coverage area of a small-scale base station (CSG base station) installed to communicate with a registered terminal (CSG terminal), It becomes possible to prevent or reduce the deterioration of the reception quality of the physical control channel of the registered terminal (non-CSG terminal).

It is a functional block diagram of the CSG base station apparatus 10 by one Embodiment of this invention. It is explanatory drawing for demonstrating the positional relationship of the CSG base station apparatus 10 and the non-CSG terminal 30. FIG. 4 is a flowchart illustrating an example of an operation of the CSG base station apparatus 10. It is explanatory drawing for demonstrating RE and REG. It is explanatory drawing for demonstrating a macrocell and a femtocell.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a functional block of a CSG base station apparatus 10 according to an embodiment of the present invention. FIG. 2 is an explanatory diagram for explaining the positional relationship between the CSG base station apparatus 10 and the non-CSG terminal 30. As shown in FIG. 2, the CSG base station apparatus 10 is an apparatus that is actually installed in the CSG base station. Therefore, in the following description, the CSG base station is also expressed as the CSG base station 10. Similarly, since the macro base station apparatus 20 is an apparatus actually installed in the macro base station, the macro base station is also referred to as the macro base station 20 in the following description.

  As shown in FIG. 1, the CSG base station apparatus 10 includes a non-CSG terminal detection unit 110 (corresponding to an unregistered terminal existence determination unit), an antenna transmission mode determination unit 120, a scheduler mode determination unit 130, and an OFDM symbol number determination unit 140. RS generator 150, downlink / uplink data channel radio resource allocator 160, downlink control channel radio resource allocator 162, PDCCH generator 164, data channel generator 166, and PCFICH generator 170.

  First, RS generation unit 150, downlink / uplink data channel radio resource allocation unit 160, downlink control channel radio resource allocation unit 162, PDCCH generation unit 164, data channel generation unit 166, and PCFICH, which are subsequent processes The generation unit 170 will be briefly described.

  The RS generation unit 150 generates an RS signal (channel quality measurement signal) of the antenna port based on the antenna communication mode (described later) notified from the antenna transmission mode determination unit 120, and performs predetermined radio resource (see FIG. 4). Place it in the

The downlink / uplink data channel radio resource allocating unit 160 is based on the antenna communication mode (described later) notified from the antenna transmission mode determining unit 120 and the scheduler mode (described later) notified from the scheduler mode determining unit 130. Then, allocation of radio resources to the data channel (PDSCH / PUSCH) is determined.
The radio resource allocation unit 162 for the downlink control channel allocates radio resources to the PDCCH based on the antenna communication mode notified from the antenna transmission mode determination unit 120 and the data channel (PDSCH / PUSCH) allocation result. decide.
The PDCCH generation unit 164 generates a PDCCH based on the PDCCH allocation result, and arranges it in a predetermined radio resource.
The data channel generation unit 166 generates a data channel (PDSCH) based on the data channel (PDSCH) assignment result and the PDCCH assignment result, and arranges the data channel (PDSCH) in a predetermined radio resource.

  The PCFICH generation unit 170 generates a PCFICH based on the number of OFDM symbols notified from the OFDM symbol number determination unit 140 and arranges it on a predetermined radio resource.

  Next, the non-CSG terminal detection unit 110, the antenna transmission mode determination unit 120, the scheduler mode determination unit 130, and the OFDM symbol number determination unit 140, which are the preceding processes, will be described.

  The non-CSG terminal detection unit 110 detects whether or not the non-CSG terminal 30 exists in the coverage area of the local station 10. That is, the non-CSG terminal detection unit 110 indicates that the non-CSG terminal 30 that was not located in the coverage area of the own station 10 is now located in the coverage area of the own station 10. The non-CSG terminal 30 located within the mobile station 10 is still located within the coverage area of the local station 10 and the non-CSG terminal 30 located within the coverage area of the local station 10 Detect that it is no longer located in the area. The non-CSG terminal detection unit 110 notifies the antenna transmission mode determination unit 120, the scheduler mode determination unit 130, and the OFDM symbol number determination unit 140 of the detection result of the non-CSG terminal 30 described above.

  Various methods can be used for the above-described detection by the non-CSG terminal detection unit 110. For example, the non-CSG terminal detection unit 110 monitors a handover request of the non-CSG terminal 30 transmitted from the macro base station 20, and whether the non-CSG terminal 30 exists in the coverage area of the local station 10 or not. Detect whether or not. Specifically, as shown in FIG. 2, when the non-CSG terminal 30 moves to the coverage area (femtocell B) of the CSG base station 10 within the coverage area (macrocell A) of the macro base station 20 (FIG. 2). 2), the macro base station 20 transmits a handover request to the CSG base station 10. Therefore, when the non-CSG terminal detection unit 110 receives a handover request from the macro base station 20 for a certain period of time, a non-CSG terminal exists within the coverage area of the local station 10. Detect the effect. Further, when the non-CSG terminal 30 moves away from the coverage area of the own station 10, there is no handover request transmitted from the macro base station 20. Accordingly, the non-CSG terminal detection unit 110 receives a handover request from the non-CSG terminal 30 transmitted from the macro base station 20 for a certain period of time, from within the coverage area of the own station 10. Detect that no longer exists.

  The antenna transmission mode determination unit 120 acquires the detection result of the non-CSG terminal 30 from the non-CSG terminal detection unit 110. When the antenna transmission mode determination unit 120 acquires the detection result of the non-CSG terminal 30, the antenna transmission mode determination unit 120 determines the antenna transmission mode of the local station 10 based on the detection result (details will be described later). The antenna transmission mode determination unit 120 notifies the determined antenna transmission mode to the RS generation unit 150, the downlink / uplink data channel radio resource allocation unit 160, the downlink control channel radio resource allocation unit 162, and the PCFICH generation unit 170. To do.

Hereinafter, a method for determining the antenna transmission mode will be described.
(1. When non-CSG terminal 30 does not exist within the coverage area of own station 10)
When the antenna transmission mode determination unit 120 acquires a detection result indicating that the non-CSG terminal 30 does not exist within the coverage area of the local station 10, the antenna transmission mode determination unit 120 determines the antenna transmission mode according to the number of antennas installed in the local station 10. To do. For example, the antenna transmission mode determination unit 120 determines a multi-antenna transmission mode using two antennas when the number of antennas installed in the local station 10 is two. In this case, the RS generation unit 150 generates channel quality measurement signals (RS signals) for the antenna ports 0 and 1 and places them in predetermined radio resources (see FIG. 4). PCFICH and PDCCH are also arranged in the two antenna ports. PDSCH allocation is performed in the multi-antenna transmission mode.

(2. When non-CSG terminal 30 exists in the coverage area of own station 10)
When the antenna transmission mode determination unit 120 obtains a detection result indicating that the non-CSG terminal 30 exists in the coverage area of the own station 10, as shown below, the presence / absence of information related to the number of antennas of the macro base station 20 Accordingly, the antenna transmission mode of the own station 10 is determined.

(2-1. When there is no information related to the number of antennas of the macro base station 20)
The antenna transmission mode determination unit 120 sets the antenna transmission mode of the local station 10 to the single antenna transmission mode regardless of the number of antennas installed in the local station 10. Moreover, the antenna transmission mode determination unit 120 determines (selects) the better average value of Wideband Channel Quality (WQ) fed back to the local station 10 as an antenna port used in the single antenna transmission mode. Therefore, when the local station 10 is equipped with two antennas, the RS generation unit 150 generates only the signal of the antenna port 0 (or 1) and arranges it in a predetermined radio resource (see FIG. 4). PCFICH and PDCCH are arranged only at antenna port 0 (or 1). PDSCH allocation is performed in the single antenna transmission mode.

(2-2. When there is information related to the number of antennas of the macro base station 20)
The antenna transmission mode determination unit 120 determines the antenna transmission mode of the local station 10 based on the following conditions. Specifically, the antenna transmission mode determination unit 120 determines the antenna transmission mode of the own station 10 based on the relationship between the number of antennas equipped in the macro base station 20 and the number of antennas of the own station 10. More specifically, the antenna transmission mode determination unit 120 determines the antenna transmission mode of the own station 10 based on the number of antennas −N installed in the macro base station 20 and the number of antennas installed in the own station 10. To decide. N is a value designated in advance as an input parameter.

(2-2-1. Number of antennas of the macro base station 20 -N> Number of antennas installed in the local station 10)
The antenna transmission mode determination unit 120 determines the antenna transmission mode of the local station 10 based on the number of antennas installed in the local station 10. Specifically, when the number of antennas installed in the own station 10 is 1, the antenna transmission mode determination unit 120 sets the antenna transmission mode of the own station 10 to the single antenna transmission mode and is installed in the own station 10. When the number of antennas> 1 is set, the antenna transmission mode of the own station 10 is set to the multi-antenna transmission mode (the number of transmission antennas = the number of antennas installed in the own station 10).
(2-2-2. Number of Antennas of Macro Base Station 20 -N ≦ Number of Antennas Equipped to Local Station 10)
The antenna transmission mode determination unit 120 determines the antenna transmission mode of the local station 10 to be the multi-antenna transmission mode according to the number of antennas −N of the macro base station 20.
(2-2-3. Number of Antennas of Macro Base Station 20 -N ≦ 1)
The antenna transmission mode determination unit 120 sets the antenna transmission mode of the local station 10 to the single antenna transmission mode.

  As described above, since the CSG base station 10 performs transmission using a smaller number of antennas than the number of transmission antennas of the macro base station 20, in the non-CSG terminal 30 existing in the femtocell of the own station 10, It becomes possible to reduce the interference by the own station 10 with respect to the downlink physical control channel received from the base station 20.

  For example, even when the RS arrangement of the own station 10 and the RS arrangement of the macro base station 20 overlap each other, the antenna port 1 of the macro base station 20 in the non-CSG terminal 30 in the coverage area of the own station 10 ( Alternatively, since there is no interference from the local station 10 for the reception of the RS signal of the antenna port 0), “Radio link failure” does not occur.

  Further, for example, even when the RS arrangement of the own station 10 and the PCFICH / PDCCH arrangement of the macro base station 20 overlap, the antenna of the macro base station 20 in the non-CSG terminal 30 within the coverage area of the own station 10 Interference from the local station 10 with respect to reception of PCFICH and PDCCH of port 1 (or antenna port 0) is reduced.

  The scheduler mode determination unit 130 acquires the detection result of the non-CSG terminal 30 from the non-CSG terminal detection unit 110. When acquiring the detection result of the non-CSG terminal 30, the scheduler mode determination unit 130 determines the scheduler mode of the local station 10 based on the detection result (details will be described later). The scheduler mode determination unit 130 notifies the determined scheduler mode to the radio resource allocation unit 160 of the downlink / uplink data channel.

Hereinafter, a method for determining the scheduler mode will be described.
(1. When non-CSG terminal 30 does not exist within the coverage area of own station 10)
When the scheduler mode determination unit 130 acquires a detection result indicating that the non-CSG terminal 30 does not exist within the coverage area of the local station 10, the scheduler mode determination unit 130 sets the scheduler mode of the local station 10 as a dynamic scheduler (mode). In the case of the dynamic scheduler, the downlink / uplink data channel radio resource allocation unit 160 of the local station 10 performs PDSCH / PDSCH / transmission of each CSG terminal for each subframe based on the CQI information fed back from each CSG terminal. A radio resource is allocated to the PUSCH.
(2. When non-CSG terminal 30 exists in the coverage area of own station 10)
When the scheduler mode determination unit 130 acquires a detection result indicating that the non-CSG terminal 30 exists in the coverage area of the local station 10, the scheduler mode determination unit 130 sets the scheduler mode of the local station 10 as a semi-persistent scheduler (mode). In the case of the semi-persistent scheduler, since the radio resource allocation in the radio resource allocation unit 160 of the downlink / uplink data channel is quasi-static (static), the radio resource in which the PDSCH / PUSCH is allocated for each subframe. Is not required to notify each CSG terminal.

  As described above, since the CSG base station 10 uses the semi-persistent scheduler when the non-CSG terminal 30 exists in its own femtocell, the non-CSG terminal 30 present in its own femtocell. Therefore, it is possible to reduce interference by the own station 10 with respect to the downlink physical control channel received from the macro base station 20.

  For example, even if the PDCCH arrangement of the own station 10 and the RS arrangement of the macro base station 20 overlap, the semi-persistent scheduler does not actually transmit the PDCCH from the own station 10, so the coverage of the own station 10 In the non-CSG terminal 30 in the area, there is no interference by the own station 10 with respect to the reception of the RS signal from the macro base station 20, and the occurrence of “Radio link failure” can be avoided.

  Further, for example, even if the RS arrangement of the own station 10 and the PCFICH / PDCCH arrangement of the macro base station 20 overlap, the semi-persistent scheduler does not transmit the PDCCH from the own station 10, and thus the coverage of the own station 10 In the non-CSG terminal 30 in the area, the interference by the own station 10 with respect to the PCFICH / PDCCH signal reception from the macro base station 20 is reduced.

  When the scheduler mode is a semi-persistent scheduler, the scheduler mode determining unit 130 changes the scheduler mode from the semi-persistent scheduler to the dynamic scheduler periodically or in an event-driven manner in order to review the radio resource allocation. You may switch. Specifically, the scheduler mode determination unit 130 measures a predetermined time with a timer when the scheduler mode is switched to the semi-persistent scheduler, and dynamically changes the scheduler mode from the semi-persistent scheduler every time the predetermined time elapses. Switch to the scheduler. Alternatively, when there is a CSG terminal that is newly RRC_Connected in the local station 10, the scheduler mode is switched from the semi-persistent scheduler to the dynamic scheduler. Since switching to the dynamic scheduler, the radio resource allocation unit 160 of the downlink / uplink data channel allocates radio resources. Thereafter, the scheduler mode determination unit 130 switches the scheduler mode from the dynamic scheduler to the semi-persistent scheduler when the non-CSG terminal 30 exists in the coverage area of the local station 10. For example, when the time set in the timer is 10 seconds, the scheduler mode determination unit 130 sets the scheduler mode to semi-persistent when detecting the non-CSG terminal 30, and changes the semi-persistent to the dynamic scheduler after 10 seconds. Switch. Since switching to the dynamic scheduler, the radio resource allocation unit 160 of the downlink / uplink data channel allocates radio resources. Thereafter, when the non-CSG terminal 30 still exists, the scheduler mode determination unit 130 switches from the dynamic scheduler to the semi-persistent scheduler.

  As described above, when the scheduler mode is switched periodically or in an event-driven manner to review the allocation of radio resources, and the non-CSG terminal 30 exists in the coverage area of the own station 10 for a long time. Even if there is, it is possible to periodically review the allocation of radio resources.

  The OFDM symbol number determination unit 140 acquires the detection result of the non-CSG terminal 30 from the non-CSG terminal detection unit 110. When the detection result of the non-CSG terminal 30 is acquired, the OFDM symbol number determination unit 140 determines the number of OFDM symbols used for the PDCCH in the local station 10 based on the detection result (details will be described later). The OFDM symbol number determination unit 140 notifies the PCFICH generation unit 170 of the determined number of OFDM symbols.

Hereinafter, a method for determining the number of OFDM symbols used for PDCCH will be described.
(1. When non-CSG terminal 30 does not exist within the coverage area of own station 10)
When the OFDM symbol number determination unit 140 acquires a detection result indicating that the non-CSG terminal 30 does not exist within the coverage area of the local station 10, the OFDM symbol number determination unit 140 sets the number of OFDM symbols of the PDCCH of the local station 10 to a value other than zero. As described above, when the number of OFDM symbols of PDCCH is a value other than 0, PCFICH generation unit 170 needs to transmit PCFICH.
(2. When non-CSG terminal 30 exists in the coverage area of own station 10)
When the OFDM symbol number determination unit 140 acquires a detection result indicating that the non-CSG terminal 30 exists in the coverage area of the local station 10, the OFDM symbol number determination unit 140 sets the number of OFDM symbols in the PDCCH of the local station 10 to zero. If the number of OFDM symbols in PDCCH is 0 (the number of OFDM symbols is 0 because the PDCCH is unnecessary in the semi-persistent scheduler), the PCFICH generation unit 170 does not need to transmit PCFICH.

  As described above, when the non-CSG terminal 30 exists in its own femtocell, the CSG base station 10 sets the number of OFDM symbols of the PDCCH to 0. Therefore, in the non-CSG terminal 30 present in its own femtocell. Thus, it is possible to reduce interference by the own station 10 with respect to the downlink physical control channel received from the macro base station 20.

  For example, even if the PCFICH arrangement of the own station 10 and the RS arrangement of the macro base station 20 overlap, the number of OFDM symbols is set to 0, and therefore the PCFICH is not actually transmitted from the own station 10. In the non-CSG terminals 30 in the 10 coverage areas, there is no interference by the own station 10 with respect to the reception of the RS signal from the macro base station 20, and the occurrence of “Radio link failure” can be avoided.

  Also, for example, even when the PCFICH arrangement of the own station 10 and the PCFICH / PDCCH arrangement of the macro base station overlap, the number of OFDM symbols is set to 0. Interference by the own station 10 with respect to PCFICH / PDCCH signal reception from the macro base station 20 in the non-CSG terminal 30 in the coverage area of the station 10 is eliminated.

  In addition, when the number of OFDM symbols is 0, the OFDM symbol number determination unit 140 periodically or event-driven changes the number of OFDM symbols from 0 to a value other than 0 in order to review the radio resource allocation. You may switch. Specifically, the OFDM symbol number determination unit 140 counts a predetermined time by a timer when the number of OFDM symbols of the PDCCH is set to 0, and sets the number of OFDM symbols other than 0 to 0 every time the predetermined time elapses. Switch to value. Alternatively, when there is a CSG terminal that is newly RRC_Connected in the local station 10, the number of OFDM symbols is switched from 0 to a value other than 0. Since the number of OFDM symbols is switched to a value other than 0, the radio resource allocation unit 160 of the downlink / uplink data channel allocates radio resources (dynamic scheduler), and the PCFICH generation unit 170 can transmit the PCFICH. It becomes like this. Thereafter, the OFDM symbol number determination unit 140 switches the number of OFDM symbols from a value other than 0 to 0 when the non-CSG terminal 30 exists in the coverage area of the local station 10. For example, when the time set in the timer is 10 seconds, the OFDM symbol number determination unit 140 sets the number of OFDM symbols to 0 when the non-CSG terminal 30 is detected, and changes from 0 to a value other than 0 after 10 seconds. Switch. Since the number of OFDM symbols is switched to a value other than 0, the PCFICH generation unit 170 can transmit the PCFICH. Thereafter, when the non-CSG terminal 30 still exists, the OFDM symbol number determination unit 140 switches the number of OFDM symbols from a value other than 0 to 0.

  As described above, if the number of OFDM symbols is switched from 0 to a value other than 0 periodically or event-driven, the non-CSG terminal 30 exists in the coverage area of the own station 10 for a long time. Even in this case, it is possible to review the assignment of radio resources and transmit the PCFICH. Note that switching to the dynamic scheduler and reviewing the radio resource allocation necessitates the transmission of PDCCH, which in turn necessitates the transmission of PCFICH. Therefore, the timing for switching the number of OFDM symbols of PDCCH and the scheduler mode are switched. Synchronized with timing. That is, the timer for switching the number of OFDM symbols of PDCCH is the same as the timer for switching the scheduler mode.

  Hereinafter, the operation of the CSG base station apparatus 10 will be described. FIG. 3 is a flowchart showing an example of the operation of the CSG base station apparatus 10. However, the flowchart shown in FIG. 3 describes processing by the non-CSG terminal detection unit 110, the antenna transmission mode determination unit 120, the scheduler mode determination unit 130, and the OFDM symbol number determination unit 140. Also, the flowchart shown in FIG. 3B is the details of the processing in step S50 in FIG.

  In FIG. 3A, the non-CSG terminal detection unit 110 determines whether or not the non-CSG terminal 30 exists in the coverage area of the local station 10 (step S10). When the non-CSG terminal detection unit 110 determines that the non-CSG terminal 30 does not exist in the coverage area of the local station 10 (step S10: No), the non-CSG terminal 30 does not exist in the coverage area of the local station 10 The antenna transmission mode determination unit 120, the scheduler mode determination unit 130, and the OFDM symbol number determination unit 140 are notified of the determination result (detection result). On the other hand, when the non-CSG terminal detection unit 110 determines that the non-CSG terminal 30 exists in the coverage area of the own station 10 (step S10: Yes), the non-CSG terminal 30 exists in the coverage area of the own station 10. The determination result (detection result) is notified to the antenna transmission mode determination unit 120, the scheduler mode determination unit 130, and the OFDM symbol number determination unit 140.

  When the antenna transmission mode determination unit 120 acquires a determination result that the non-CSG terminal 30 does not exist in the coverage area of the local station 10 (step S10: No), the antenna transmission mode determination unit 120 depends on the number of antennas installed in the local station 10. The antenna transmission mode is determined (step S20). On the other hand, when the antenna transmission mode determination unit 120 obtains a determination result indicating that the non-CSG terminal 30 exists in the coverage area of the own station 10 (step S10: Yes), information on the number of antennas of the macro base station 20 Based on the presence or absence, the antenna transmission mode of the own station 10 is determined (step S22).

  When the scheduler mode determination unit 130 obtains the determination result that the non-CSG terminal 30 does not exist in the coverage area of the local station 10 (step S10: No), the scheduler mode of the local station 10 is changed to step S20. The dynamic scheduler is determined (step S30). On the other hand, when the scheduler mode determination unit 130 obtains the determination result that the non-CSG terminal 30 exists in the coverage area of the local station 10 (step S10: Yes), the scheduler of the local station 10 continues to step S22. The mode is determined to be a semi-persistent scheduler (step S32).

  When the OFDM symbol number determination unit 140 obtains a determination result indicating that the non-CSG terminal 30 does not exist in the coverage area of the local station 10 (step S10: No), the PDCCH of the local station 10 continues from step S30. The number of OFDM symbols is determined to a value other than 0 (step S40). On the other hand, when the OFDM symbol number determining unit 140 obtains a determination result indicating that the non-CSG terminal 30 is present in the coverage area of the local station 10 (step S10: Yes), following the step S32, The number of PDCCH OFDM symbols is determined to be 0 (step S42).

  Subsequent to step S40 or step S42, the scheduler mode determination unit 130 / OFDM symbol number determination unit 140 executes timer processing (FIG. 3B), and the flowchart of FIG.

  In FIG. 3B, the scheduler mode determination unit 130 determines whether or not the current scheduler mode is a semi-persistent scheduler (step S52). When the scheduler mode determination unit 130 determines that the current scheduler mode is not a semi-persistent scheduler (step S52: No), the flowchart of FIG. 3B ends, and the process returns to FIG. The flowchart of a) is also terminated.

  When the scheduler mode determination unit 130 determines that the current scheduler mode is a semi-persistent scheduler (step S52: Yes), it determines whether or not a predetermined time has passed since the scheduler mode determination unit 130 has become a semi-persistent scheduler (step S54). ). When the scheduler mode determination unit 130 determines that the predetermined time has not elapsed since the semi-persistent scheduler has been used (step S54: No), the flowchart of FIG. 3B ends and returns to FIG. 3A. Then, the flowchart of FIG.

  If the scheduler mode determining unit 130 determines that a predetermined time has elapsed since the scheduler mode determination unit 130 has become a semi-persistent scheduler (step S54: Yes), the scheduler mode of the local station 10 is determined to be a dynamic scheduler (step S130). That is, the scheduler mode determination unit 130 switches the scheduler mode from the semi-persistent scheduler to the dynamic scheduler. Next, the OFDM symbol number determination unit 140 determines the number of OFDM symbols of the PDCCH of the local station 10 to a value other than 0 (step S140). That is, the OFDM symbol number determination unit 140 switches the number of OFDM symbols from 0 to a value other than 0.

  Subsequent to step S140, the scheduler mode determination unit 130 determines the scheduler mode of the local station 10 as a semi-persistent scheduler (step S232). That is, the scheduler mode determination unit 130 switches the scheduler mode from the dynamic scheduler to the semi-persistent scheduler. Next, the OFDM symbol number determination unit 140 determines the number of OFDM symbols of the PDCCH of the local station 10 as 0 (step S242). That is, the OFDM symbol number determination unit 140 switches the number of OFDM symbols from a value other than 0 to 0. Then, the flowchart of FIG. 3B is ended, and the flowchart of FIG. 3A is ended after returning to FIG.

  It should be noted that the above-described determination processing by the non-CSG terminal detection unit 110 (whether or not the non-CSG terminal 30 exists in the coverage area of the local station 10) between step S140 and step S232 in the flowchart shown in FIG. May be executed. That is, when the scheduler mode determination unit 130 obtains the determination result that the non-CSG terminal 30 exists, the scheduler mode is switched from the dynamic scheduler to the semi-persistent scheduler, and the determination result that the non-CSG terminal 30 does not exist. Is obtained, the scheduler mode may remain the dynamic scheduler. Similarly, when the OFDM symbol number determination unit 140 obtains a determination result that the non-CSG terminal 30 exists, the OFDM symbol number determination unit 140 switches the number of OFDM symbols from a value other than 0 to 0, and indicates that the non-CSG terminal 30 does not exist. When the determination result is acquired, the number of OFDM symbols may be left as a value other than zero.

  Further, step S50 (FIG. 3B) may be omitted in the flowchart shown in FIG.

  As described above, according to the CSG base station apparatus 10 according to the embodiment of the present invention, when a terminal (non-CSG terminal) that cannot communicate with the local station 10 exists in the coverage area of the local station 10, physical control of the terminal is performed. It becomes possible to prevent or reduce a decrease in reception quality of channels (RS, PCFICH, PDCCH).

  In the above embodiment, as shown in FIG. 1, the CSG base station apparatus 10 includes a non-CSG terminal detection unit 110, an antenna transmission mode determination unit 120, a scheduler mode determination unit 130, an OFDM symbol number determination unit 140, An aspect including an RS generation unit 150, a downlink / uplink data channel radio resource allocation unit 160, a downlink control channel radio resource allocation unit 162, a PDCCH generation unit 164, a data channel generation unit 166, and a PCFICH generation unit 170 will be described. However, the CSG base station apparatus 10 may include only the non-CSG terminal detection unit 110, the antenna transmission mode determination unit 120, the scheduler mode determination unit 130, and the OFDM symbol number determination unit 140.

  In addition, a program for executing each process of the CSG base station apparatus 10 according to an embodiment of the present invention is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system, By executing, the above-described various processes related to each process of the CSG base station apparatus 10 according to the embodiment of the present invention may be performed. Here, the “computer system” may include an OS and hardware such as peripheral devices. Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used. The “computer-readable recording medium” means a flexible disk, a magneto-optical disk, a ROM, a writable nonvolatile memory such as a flash memory, a portable medium such as a CD-ROM, a hard disk built in a computer system, etc. This is a storage device.

  Further, the “computer-readable recording medium” means a volatile memory (for example, DRAM (Dynamic DRAM) in a computer system that becomes a server or a client when a program is transmitted through a network such as the Internet or a communication line such as a telephone line. Random Access Memory)), etc., which hold programs for a certain period of time. The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, what is called a difference file (difference program) may be sufficient.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

10 CSG base station (CSG base station equipment)
20 Macro base station (macro base station equipment)
30 Non-CSG terminal 110 Non-CSG terminal detection unit (unregistered terminal existence determination unit)
120 antenna transmission mode determination unit 130 scheduler mode determination unit 140 OFDM symbol number determination unit 150 RS generation unit 160 downlink / uplink data channel radio resource allocation unit 162 downlink control channel radio resource allocation unit 164 PDCCH generation unit 166 data Channel generator 170 PCFICH generator

Claims (9)

In a base station device that communicates only with pre-registered registration terminals,
An unregistered terminal existence determination unit that determines whether an unregistered terminal that is a terminal other than the registered terminal exists in the coverage area of the local station;
Based on the determination result by the unregistered terminal existence determination unit, an antenna transmission mode determination unit that determines the antenna transmission mode of the own station;
Based on the determination result by the unregistered terminal existence determination unit, a scheduler mode determination unit that determines the scheduler mode of the own station;
A base station apparatus comprising: an OFDM symbol number determination unit that determines the number of OFDM symbols used by a physical control channel that notifies radio resource allocation information based on a determination result by the unregistered terminal existence determination unit. The antenna transmission mode determination unit
When it is determined by the unregistered terminal presence / absence determination unit that there is no unregistered terminal in the coverage area of the own station, the antenna transmission mode is determined according to the number of antennas installed in the own station,
If the unregistered terminal presence / absence determining unit determines that there is an unregistered terminal in the coverage area of the own station, the antenna is determined depending on whether there is information on the number of antennas of other base stations with which the unregistered terminal communicates. The base station apparatus according to claim 1, wherein a transmission mode is determined. The antenna transmission mode determination unit
When it is determined by the unregistered terminal presence / absence determining unit that there is an unregistered terminal in the coverage area of the own station, when there is no information on the number of antennas of the other base station, the antenna transmission mode is set to a single antenna. When the transmission mode is determined and there is information on the number of antennas of the other base station, the antenna transmission mode is determined based on the relationship between the number of antennas of the other base station and the number of antennas of the own station. The base station apparatus according to claim 2, wherein: The antenna transmission mode determination unit
When the antenna transmission mode is determined to be the single antenna transmission mode, as the antenna port used in the single antenna transmission mode, the one having the better average value of Wideband CQI (Wideband Channel quality) fed back to the own station is selected. The base station apparatus according to claim 3, wherein: The scheduler mode determination unit
When it is determined by the unregistered terminal presence / absence determination unit that there is no unregistered terminal in the coverage area of the own station, the scheduler mode is determined as a dynamic scheduler mode,
5. The scheduler mode is determined to be a semi-persistent scheduler mode when the unregistered terminal existence determination unit determines that an unregistered terminal exists in the coverage area of the own station. The base station apparatus according to any one of the above. The scheduler mode determination unit
6. The base station according to claim 5, wherein when the scheduler mode is a semi-persistent scheduler, the scheduler mode is switched from the semi-persistent scheduler mode to the dynamic scheduler mode periodically or in an event-driven manner. apparatus. The OFDM symbol number determination unit includes:
When it is determined by the unregistered terminal presence / absence determination unit that there is no unregistered terminal in the coverage area of the local station, the number of OFDM symbols is determined to a value other than 0,
The number of OFDM symbols is determined to be 0 when the unregistered terminal existence determination unit determines that there is an unregistered terminal in the coverage area of the own station. The base station apparatus according to item 1. The OFDM symbol number determination unit includes:
The base station apparatus according to claim 7, wherein when the number of OFDM symbols is 0, the number of OFDM symbols is switched from 0 to a value other than 0 periodically or event-driven. In the computer of the base station device that communicates only with pre-registered registration terminals,
A determination step of determining whether or not an unregistered terminal that is a terminal other than the registered terminal exists in the coverage area of the own station;
Based on the determination result of the determination step, an antenna transmission mode determination step of determining the antenna transmission mode of the own station;
A scheduler mode determination step for determining a scheduler mode of the own station based on a determination result by the determination step;
A program for executing an OFDM symbol number determination step for determining the number of OFDM symbols used by a physical control channel that notifies radio resource allocation information based on a determination result of the determination step.

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