JP2010178237A - Communication system and base station device, terminal device, and base station device, and program executed by terminal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mechanism for effectively reducing interference in a coordinated multipoint base station communication system which is a radio communication system for using a plurality of frequency bands to perform communication, and performed by a plurality of base station devices in the communication system by performing simultaneous communication with one terminal device, or performed by the plurality of base station devices by arbitrating the timing of communication with the one terminal device. <P>SOLUTION: The radio communication system prepares: a means for measuring an interference amount in a base station device; a means for measuring traffic in a cell; a means for exchanging the interference amount, the traffic, a cell identifier and a frequency band identifier between base stations in accordance with a traffic state in the cell; a means for determining an interference arbitration system from exchanged information; a means for performing radio resource management setting on the basis of the determined interference arbitration system; and a means for notifying terminal devices in each cell of the information of the radio resource management setting wherein the terminal devices reduce interference by determining whether to perform transmission and reception on the basis of the information of the radio resource management setting notified from the base station device. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a communication system and a base station apparatus and a terminal apparatus thereof, and more specifically, a communication system using a plurality of frequency bands, an inter-cell interference cancellation and reduction technique in the communication system, and a base used in the system. The present invention relates to a station apparatus and a terminal apparatus.

  In a wireless communication system, high-speed transmission technology, broadband system technology, and quality of service (QoS) maintenance technology are important requirements. As a technique for satisfying these requirements, multiple input multiple output (MIMO), orthogonal frequency division multiplexing (OFDM), radio resource management (RRM), and radio resource management (RRM) band (CA: Carrier Aggregation), inter-cell interference cancellation / arbitration (ICIC: Inter-Cell Interference Cancellation / Coordination), cooperative multi-base station communication (CoMP: Coordinated MultiPoint), and the like. These technologies enable high-speed transmission.

  FIG. 23 is a diagram illustrating a mechanism of inter-cell interference reduction and interference cancellation in a long term evolution (LTE) system. The base station device BS300 and the terminal device UE300 communicate with each other. Similarly, the base station apparatus BS301 and the terminal apparatuses UE301 and UE302 communicate with each other between the base station apparatus BS302 and the terminal apparatus UE303. In the case of the LTE system, one frequency band is used.

Each base station apparatus first performs control so that the power from each terminal apparatus is minimized. The power of the terminal device is given by the following equation. The power P of the terminal device is determined by the following equation based on parameters instructed by the network.
P = min (Pmax, 10logM + Po + αPL + delta_mcs + f (delta_i))
Here, Pmax is the maximum transmittable power for each terminal device, M is the number of resource blocks instructed in uplink resource allocation, Po is a default power value determined for each cell, α is a propagation loss compensation coefficient for each cell, PL Is a propagation loss of a downlink signal calculated by the terminal device, delta_mcs is a value determined and notified by the upper layer, delta_i is a correction value for each terminal instructed together with resource allocation, and the function f () is the upper layer Absolute value function or cumulative function indicated by the layer.

  Next, the base station apparatus measures an interference amount due to an uplink signal from a terminal apparatus existing in another cell as an overload indicator (OI). In addition, the base station estimates an amount that a terminal existing at the cell edge of the own cell will interfere with another cell as an over interference indicator (HII). These OI and HII are exchanged between base stations through an information exchange line between base stations called an X2 line, and are used for interference reduction and interference removal. The base station that has received the overload OI controls to reduce the transmission power of the terminal device at the cell edge, and reduces interference with other cells. Moreover, the base station which received HII which is excessive interference prevents the influence by the interference from another cell by not using the carrier frequency. The base station also measures the amount of interference (IoT: Interference over Thermal). Also, interference with other cells is reduced by controlling the downlink power transmitted from the base station apparatus to the terminal apparatus to be the minimum necessary.

  More specifically, the base station apparatus BS300 uses each resource block of the used frequency band (the used frequency band is a frequency band that is a minimum unit necessary for communication, divided into a plurality of used frequency bands. Each time a plurality of communication is performed), the amount of interference (IoT) of the signal of the received neighboring cell is measured. Next, the base station apparatus BS300 compares the measured IoT with a threshold value, and defines OI = 1 if it is larger than the threshold value, and OI = 0 if smaller. FIG. 24 shows a method for defining OI. When the base station apparatus BS300 detects whether the terminal apparatus UE300 is at the cell edge and determines that the transmission power of the terminal apparatus UE300 is large and affects the other cells, the HII determines that the terminal apparatus UE300 The resource block being used is defined as HII = High. Further, the base station apparatus BS300 measures the amount of traffic in the own cell and uses the information as a traffic load index (TLI). These OI, HII, and TLI are sent to other base station apparatuses BS301 and BS302 through the X2 line. It also receives OI, HII and TLI information from these base stations. When it is received as OI = 1, the terminal device is supported so as to reduce the transmission power of the terminal device in the own cell using the resource block. Thereafter, the base station apparatus BS300 further performs IoT measurement, determines OI, performs HII and TLI measurements, and repeatedly exchanges them through the X2 line.

  FIG. 25 is a diagram illustrating a channel configuration example in LTE. The downlink of LTE (communication from the base station apparatus BS to the terminal apparatus MS) includes a downlink control area designation channel (PCFICH: Physical Control Format Channel) and a downlink complex retransmission request channel (PHICH: Physical Hybrid ARQ Indicator). ), Downlink multicast channel (PMCH: Physical Multicast Channel), downlink shared channel (PDSCH: Physical Downlink Shared Channel), and downlink control channel (PDCCH: Physical Downlink Control Channel) al Boradcast Channel), and is made of. Further, a synchronization signal (SCH) that is a reference signal for the terminal device to synchronize with the base station, and a reference signal (RS: Reference Signal) used as a reference when measuring signal quality or demodulating the received signal are also provided. Sent.

The LTE uplink (communication from the terminal apparatus MS to the base station apparatus BS) includes a random access channel (RACH: Random Access Channel), an uplink shared channel (PUSCH), an uplink control channel ( PUCCH: Physical Uplink Control Channel). In addition, a reference signal (RS: Reference Signal) used as a standard for signal quality measurement and reception signal demodulation is also transmitted. (For example, see Non-Patent Document 7 below).

3GPP TS 36.814, V0.3. 1 (2009-01), 3rd Generation Partnership Project (Technical Specification Group Radio Access Network ---------------------------------------------------------------_ “Text proposal for capturing aggregations on support of wizard bandwidths”, 3GPP TSG RAN WG1 Meeting # 55, Nokia, Nokia Siemens Network 80, No. “New Interface Scenarios in LTE-Advanced”, 3GPP TSG RAN WG1 Meeting # 54bis, Qualcomm Europe, Prague, Czech Republic, Sept. 9-80 80-3 “Coordinated Multi-Point downlink transmission in LTE-Advanced”, 3GPP TSG RAN WG1 Meeting # 55, Qualcomm Europe, Prague, Czech Reverb 400 “Carrier Aggregation in Heterogeneous Networks”, 3GPP TSG RAN WG1 Meeting # 55bis, Qualcomm Europe, Ljubljana, Slovenia, January 12-19, 35R “Inter-cell Radio Resource Management for Heterogeneous Networks”, 3GPP TSG RAN WG1 Meeting # 55, NTT DOCOMO, Prague, Czech Republish, Nove3R310-4 3GPP TS 36.211, V8.5.0 (2008-12), Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA);

Inter-cell interference cancellation systems are important in wireless long term evolution-advanced (LTE-A) systems. When cooperative multi-base station communication is not performed, the terminal apparatus receives interference from the adjacent cell. FIG. 26 shows an example of inter-cell interference in the LTE-A system. The terminal device UE100 receives the signal of the base station device BS100. The terminal apparatus UE100 is interfered by signals from other base station apparatuses BS101 and BS102 that use the same frequency band BW1.
When performing coordinated multi-base station communication, the terminal device uses the resources of the adjacent cell that should be an interference source in the self-terminal as coordinated multi-base station communication, so the problem is reduced. However, a terminal apparatus that performs coordinated multiple base station communication is usually located at the cell edge, and receives or gives interference from a cell of a base station that does not perform coordinated multiple base station communication. Further, when the terminal device moves inside the cell, when the coordinated multi-base station communication is not performed, the handover is performed to the closest cell or the cell having a strong electric field strength, so that the base station can communicate with the base station with a minimum power. Although communication is not performed between terminal devices, when performing coordinated multi-base station communication, communication is also performed with a base station of a cell other than the nearest cell with a strong electric field strength, and may receive or give interference. Become more.

  In order to solve such a problem, the present invention is a wireless communication system that performs communication using a plurality of frequency bands, wherein a plurality of base station apparatuses in the communication system simultaneously communicate with one terminal apparatus, or a plurality of In a coordinated multi-base station communication system in which the base station apparatus arbitrates communication timing with respect to one terminal apparatus, means for measuring the amount of interference in the base station apparatus, means for measuring traffic in the cell, and amount of interference And means for exchanging traffic, cell identifiers and frequency band identifiers between base stations according to the traffic state in the cell, means for determining an interference arbitration scheme from the exchanged information, and based on the determined interference arbitration scheme Means for performing radio resource management setting and means for notifying information of radio resource management setting to a terminal device in each cell, the terminal device In FIG. 5, interference is reduced by determining whether to perform transmission / reception based on the radio resource management setting information notified from the base station apparatus.

  In addition, the interference amount measurement performed by the base station device is performed by each base station independently measuring the downlink interference amount for each terminal device, the downlink interference amount for each cell, or for each cell. By measuring the amount of uplink interference, interference measurement according to the system is performed, and interference is effectively reduced.

  In addition, the downlink interference amount measurement for each terminal device is performed using an overload index and a frequency band identifier for each downlink resource block, an overload index for each downlink frequency band, or an overload index for each downlink resource block using a plurality of bits. This is performed for one to a plurality of frequency band identifiers or overload indicators for each downlink frequency band using a plurality of bits.

  Further, the downlink interference amount measurement for each cell is performed by measuring the overload index and frequency band identifier for each downlink resource block, or the overload index for each downlink frequency band, or the overload index and frequency for each downlink resource block using multiple bits. This is performed for one to a plurality of band identifiers or overload indicators for each downlink frequency band using a plurality of bits.

  In addition, the uplink interference amount measurement for each cell is performed by measuring the overload index and frequency band identifier for each uplink resource block, or the overload index for each uplink frequency band, or the overload index and frequency for each uplink resource block using multiple bits. This is performed for one to a plurality of band identifiers or overload indicators for each upstream frequency band using a plurality of bits.

  Further, as an interference arbitration method, when a terminal apparatus performs a plurality of base station communications, flexible resource allocation is realized by performing partial frequency reuse or soft frequency reuse.

  Alternatively, when the terminal apparatus does not perform a plurality of base station communications, the interference arbitration method obtains a large interference reduction effect by assigning different frequency bands to terminal apparatuses at different cell edges.

  Alternatively, the interference arbitration method obtains a large interference reduction effect by assigning different frequency bands to a terminal apparatus that performs multiple base station communication in different cells and a terminal apparatus that does not perform multiple base station communication.

  In addition, notification of radio resource management setting information to the terminal device in each cell is performed using one or more of a broadcast channel, a downlink control channel, or a downlink shared channel.

  In addition, the determination of the interference arbitration method and the determination of the radio resource management setting are performed according to the capability regarding the frequency band that can be used by the terminal device.

  The interference arbitration method is a frequency division interference arbitration method using downlink power control in a heterogeneous base station network, or a downlink frequency division interference arbitration method in the same type of base station network, or a downlink transmission stop method for each frequency band, or a frequency band. One to a plurality of base station communication methods for each frequency band or an uplink transmission method for each frequency band are used.

  Further, the base station apparatus determines the means for measuring the amount of interference, the means for measuring traffic in the cell, and the amount of interference, the traffic, the cell identifier, and the frequency band identifier according to the state of traffic in the cell. Means for exchanging between, means for determining an interference arbitration scheme from the exchanged information, means for performing radio resource management settings based on the determined interference arbitration scheme, and information on the radio resource management settings in each cell Means for notifying the terminal device.

  Further, the terminal device has means for determining whether to perform transmission / reception based on the information of the radio resource management setting notified from the base station device.

  In addition, the control method includes a step of measuring an amount of interference, a step of measuring traffic in the cell, and the amount of interference, the traffic, the cell identifier, and the frequency band identifier according to a state of traffic in the cell. A step of exchanging between base stations, a step of determining an interference arbitration scheme from the exchanged information, a step of performing radio resource management setting based on the determined interference arbitration scheme, and information of the radio resource management setting And notifying the terminal device in the cell.

  You may provide these as a program for making a computer perform the method of the above-mentioned, and a recording medium which recorded this program. The program may be acquired from a transmission medium such as the Internet.

  The wireless communication system of the present invention can effectively reduce inter-cell interference in a communication system in which a plurality of component carriers exist.

It is a figure showing the radio | wireless communications system by the 1st Embodiment of this invention. It is a figure which shows the element used for the interference reduction process for every network in this invention. It is a figure which shows the basic operation | movement of the interference reduction process in this invention. It is a figure showing the interference between each base station in this invention, and the signaling accompanying it. FIG. FIG. 5 is a diagram showing an example in which the present invention is applied to a heterogeneous base station network, which is another embodiment of the present invention. FIG. 6 is a flowchart showing the processing of the communication system according to the first embodiment of this invention. It is a figure in the case of setting the setting of the interference amount of the downlink signal in embodiment in this invention for every terminal. It is a figure showing the relationship between a frequency band and OI in the case of setting the amount of interference of the downlink signal in embodiment in this invention for every terminal. It is a figure of the other example in the case of setting the interference amount of the downlink signal in embodiment in this invention for every cell. It is a figure showing the relationship between a frequency band and OI in the case of setting the amount of interference of the downlink signal in embodiment in this invention for every cell. It is a figure showing the example which performs an interference reduction process using the frequency division system in other embodiment in this invention. It is a flowchart showing the process of the communication system of other embodiment of this invention. It is a figure showing the example of the setting method of the interference amount of the uplink signal in other embodiment in this invention. It is a figure showing the relationship between the frequency band and OI in the setting of the interference amount of the upstream signal in other embodiment in this invention. It is a figure showing the other example of interference reduction in embodiment of this invention. It is a figure showing the interference reduction method of the downlink signal in the multiple base station communication in case communication is simultaneously performed with respect to one terminal device from the multiple base station apparatus which is another embodiment of the present invention. It is a flowchart showing the process of the communication system in FIG. It is a figure showing the interference reduction method of the uplink signal in the multiple base station communication when communication is simultaneously performed from one terminal device to multiple base station apparatuses, which is another embodiment of the present invention. It is a flowchart showing the process of the communication system in FIG. It is a figure showing the structure of the base station apparatus in this invention. It is a figure showing the structure of the terminal device in this invention. It is a figure showing the system configuration | structure in this invention. It is a figure showing the mechanism of the interference reduction between cells in the LTE system which is a prior art, and the mechanism of interference removal. It is a figure showing the setting method of OI in a LTE system. It is a figure which shows the channel structural example in LTE. FIG. 26 is a diagram illustrating an example of inter-cell interference in the LTE-A system.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present invention, different types of base stations, for example, base stations with different cell radii, home base stations (Home-eNB), relay stations, and bases for subscriber-limited cell (CSG: Closed Subscriber Group) cells Interference reduction processing based on frequency bands is performed in a communication system using a plurality of frequency bands in a heterogeneous base station network in which stations and the like are mixed or in a homogeneous base station network composed of the same kind of base stations.

  First, a first embodiment of the present invention will be described. FIG. 1 is a diagram illustrating a wireless communication system according to a first embodiment of the present invention. The communication system uses five frequency bands (BW1 to BW5). Base station apparatus BS400 communicates with terminal apparatus UE400 in its own cell using the first frequency band. Similarly, base station apparatus BS401 communicates with terminal apparatus UE401 in its own cell using the second frequency band, and base station apparatus BS402 communicates with terminal apparatus UE403 in its own cell using the third frequency band. By performing communication using different frequency bands, it is possible to reduce mutual inter-cell interference.

  The selection of the frequency band to be used is determined according to the capability regarding the frequency band that the terminal device can use. The radio resource management means is set based on the determined use frequency band. Further, uplink power control and downlink power control are used in combination. Such power control is particularly effective in a heterogeneous base station network. In the same type of base station network, since the cell radii covered by the network are equal, it is effective to mainly use uplink power control. In order to perform power control, OI measurement and HII measurement are performed for each cell and each terminal device. The measured OI and HII information is exchanged with the base station apparatus of another cell through the X2 line together with the frequency band identifier. FIG. 2 shows elements used for interference reduction processing for each network in the present invention. For homogeneous networks and heterogeneous networks, in the present invention, interference reduction processing for each frequency band using a frequency band identification code, IoT, OI, HII measurement for each frequency band, power control, and the frequency band used based on terminal capability Performs interference control by allocation, radio resource management, and interference reduction in multiple base station communications. FIG. 3 shows the basic operation of the interference reduction processing in the present invention.

  FIG. 4 is a diagram showing the interference between base stations and the accompanying signaling in the present invention. The communication system uses five frequency bands (BW1 to BW5). Base station apparatus BS500 communicates with terminal apparatus UE500 in its own cell using one or more frequency bands of BW1 to BW5. The same applies to base station apparatuses BS501 and UE501, UE502, and base station apparatuses BS502 and UE503. Here, each base station apparatus BS500, BS501, BS502 measures the amount of interference for each frequency band. If the measured interference amount exceeds the threshold, it is determined that OI has occurred. In this case, OI occurs in the third frequency band in the cell of BS500. Similarly, OI occurs in the second frequency band and the fourth frequency band in the cell of BS501, and in the fifth frequency band in the cell of BS502. The measurement of HII and TLI is similarly performed. Each base station apparatus exchanges the measured OI, HII, and TLI information using an X2 line together with a frequency band identifier (CC ID: Component Carrier ID) for distinguishing frequency bands. The information is also transmitted to the network center NC500, and the network center performs radio resource management by integrating the base stations based on the information. As described above, in the present invention, the OI and the like for each frequency band are measured and transmitted together with the CC ID, thereby enabling interference reduction processing using the CC.

  FIG. 5 is a diagram showing an example in which the present invention is applied to a heterogeneous base station network, which is another embodiment of the present invention. Base station apparatus BS600 communicates with terminal apparatus UE600 in its own cell using the frequency bands BW1 to BW4. Similarly, base station apparatus BS601 communicates with terminal apparatus UE601 in its own cell using the frequency bands of BW1, BW3 to BW5, but the cell radius of base station apparatus BS601 is smaller than that of base station apparatus BS600. . In addition, the base station apparatus BS602 having a smaller cell radius communicates with the terminal apparatus UE602 in the own cell using the frequency band of BW2 to BW5.

  Assume that an OI is occurring between a base station apparatus BS600 having a large cell radius and a base station apparatus BS601 having a relatively large cell radius. At this time, it is assumed that no OI occurs in BW3 in base station apparatus BS602 with a small cell radius. BS600 uses BW3 for communication with UE600, and BS601 avoids interference by using other frequency band BS601. The base station apparatus BS602 having a small cell radius uses the BW3 because no OI has occurred.

  Next, the use of a frequency band according to the characteristics of the used frequency band will be described. The frequency band used for BW1 is 450 MHz, the frequency band used for BW2 is 700 MHz, the frequency band used for BW3 is 2 GHz, the frequency band used for BW4 is 3 GHz, and the frequency band used for BW5 is 4 GHz. Generally, the higher the frequency, the greater the amount of reduction during propagation and the smaller the cell radius. In the present invention, when interference occurs, the interference is reduced by using a frequency band having a large attenuation.

  Furthermore, interference is reduced by not using the same or adjacent frequency bands.

  FIG. 6 is a flowchart showing the processing of the communication system according to the first embodiment of this invention. When considering interference reduction processing between cells of two base station apparatuses, assuming that one base station is a service BS and the other is an adjacent BS, each base station apparatus first transmits a downlink signal reported from a terminal apparatus in each cell. The channel state (CSI: Channel State Information) is measured (Step S100). Next, each base station apparatus measures the amount of interference (Step S101), and calculates OI, HII, and TLI for each frequency band (Step S102). Each piece of calculated information is exchanged with other base stations via the X2 line according to the load (Step S103). The base station apparatus that has received the information determines an interference reduction method according to the received information, and sets radio resource management (RRM) parameters based on the method (Step S104). Based on the set RRM parameter, each base station apparatus notifies the RRM information to the terminal apparatus of its own cell (Step S105). The base station device continues to set the downlink power control amount, power distribution, bit arrangement, and transmission method (Step S106), and transmits a signal to the terminal device of its own cell (Step S107). Further, the base station apparatus determines whether to perform transmission to the terminal apparatus to another cell based on the information from the exchanged other cell (Step S108). Thereafter, the terminal apparatus performs feedback of CSI information for the base station apparatus (Step S109).

  FIGS. 7 and 8 show a method for setting the downlink signal interference amount in the embodiment of the present invention, and show an example of setting for each terminal. Since interference due to downlink signals varies depending on the position of the terminal apparatus even in the same cell, it is desirable to measure the amount of interference for each terminal. In FIG. 7, base station apparatus BS700 communicates with terminal apparatus UE700. Similarly, the base station device BS701 communicates with the terminal devices UE701 and UE702, and the base station device BS702 communicates with the terminal device UE703. The terminal devices UE701 and UE702 existing in the cell of the base station device BS701 are interfered by a downlink signal from the base station device BS700 which is a base station of another cell. Terminal apparatuses UE701 and UE702 report the amount of downlink signal interference to base station apparatus BS701 in the own cell. The amount of interference is reported to the base station apparatus using an uplink control channel or an uplink common channel. Base station apparatus BS701 calculates the OI of a downlink signal based on the reported interference amount. Further, exchange of OI information between base stations is performed using an X2 line.

  The OI calculation may be performed for each frequency band, or may be performed for each frequency band, for example, in units of resource blocks. A plurality of threshold values may be set, and the number of OI bits may be a plurality of bits. By doing in this way, it becomes possible to measure and control a fine interference amount. FIG. 8 shows an example of the definition of OI. FIG. 8A shows a method in which one threshold value is provided and defined in resource block units. FIG. 8B shows a method in which one threshold is provided and one OI is defined for the entire frequency band. FIG. 8C shows a method in which two threshold values are provided and defined in units of resource blocks. In this case, the number of bits required for OI is 2 bits per resource block. FIG. 8D shows a method in which a plurality of threshold values are provided and defined in units of resource blocks.

  In this description, OI is described, but the same method can be used for defining HII.

  As described above, in the present invention, by defining OI and HII for each terminal for the downlink signal and exchanging with each base station layer replacement, it is possible to effectively reduce the interference for the downlink signal.

  FIG. 9 and FIG. 10 show an example of a method for setting the downlink signal interference amount in another embodiment of the present invention, which is an example of setting for each cell. In the present embodiment, the amount of downlink signal interference is set not for each terminal but for each cell. Each base station apparatus BS800, BS801, BS802 measures the amount of downlink signal interference from another cell by itself and calculates the amount of downlink signal interference. Further, exchange of OI information between base stations is performed using an X2 line. By calculating the OI for each cell in this way, measurement and reporting procedures by the terminal device can be omitted, and the amount of information exchanged using the X2 line can be reduced.

  The calculation of OI may be performed for each frequency band as in the case of calculating for each cell as described above, or may be performed for each frequency band, for example, in units of resource blocks. A plurality of threshold values may be set, and the number of OI bits may be a plurality of bits. FIG. 10 shows an example of the definition of OI. FIG. 10A shows a method in which one threshold value is provided and defined in resource block units. FIG. 10B shows a method in which one threshold value is provided and one OI is defined for the entire frequency band. FIG. 10C shows a method in which two threshold values are provided and defined in units of resource blocks. In this case, the number of bits required for OI is 2 bits per resource block. FIG. 10D shows a method in which a plurality of threshold values are provided and defined in resource block units.

  FIG. 11 is a diagram illustrating another embodiment of the present invention, and illustrates an example in which interference reduction processing is performed using a frequency division method. Base station apparatus BS900 communicates with terminal apparatuses UE900, UE901, and UE902. Base station apparatus BS901 communicates with terminal apparatus UE903, and base station apparatus BS902 communicates with terminal apparatus UE904.

  Now, it is assumed that each terminal device has a capability of performing communication using a plurality of frequency bands. The terminal apparatuses UE901 and UE902 existing at positions where there is no possibility of causing interference with other cells perform communication using a plurality of frequency bands. For the terminal devices UE900, UE903, and UE904 that are located at the cell edge and that may receive interference from other cells, allocation of usable frequency bands is performed using a frequency division scheme. For example, when the frequency band BW3 is generated in the cell of BS900, the frequency band BW2 is generated in the cell of BS901, and the frequency band BW4 is generated in the cell of BS902, the terminal at the cell end uses in each cell. The frequencies are allocated so as not to interfere with each other and to avoid the frequency band in which OI occurs. BW1 is allocated to the terminal device UE900, a frequency band 903 is allocated to the terminal device UE903, and BW4 is allocated to the terminal device UE904.

  By assigning the frequency division method in this way, it is possible to avoid interference for terminals located at the cell edge while efficiently allocating interference while allocating a wide frequency band to terminals not located at the cell edge. Can do.

  FIG. 12 is a flowchart showing the processing of the communication system according to another embodiment of the present invention, and shows the interference reduction processing of the uplink signal. When considering interference reduction processing between cells of two base station apparatuses, assuming that one base station is a service BS and the other is an adjacent BS, each base station apparatus first transmits an uplink signal channel from a terminal apparatus in each cell. The situation (CSI: Channel State Information) is measured (Step S200). Next, each base station apparatus measures the amount of interference (Step S201), and calculates OI, HII, and TLI for each frequency band (Step S202). Each piece of calculated information is exchanged with other base stations via the X2 line according to the load (Step S203). The base station apparatus that has received the information determines an interference reduction method according to the received information, and sets radio resource management (RRM) parameters based on the method (Step S204). Based on the set RRM parameter, each base station apparatus notifies the RRM information to the terminal apparatus of its own cell (Step S205). The base station device continues to set the uplink power control amount, power distribution, bit arrangement, and transmission method (Step S206), and transmits a signal to the terminal device of its own cell (Step S207). The terminal device that has received the signal determines whether or not to transmit an uplink signal based on the information (Step S208). Thereafter, the terminal apparatus performs feedback of CSI information for the base station apparatus (Step S209).

  FIG. 13 and FIG. 14 show an example of an uplink signal interference amount setting method in another embodiment of the present invention. Each base station apparatus BS1000, BS1001, BS1002 measures the amount of interference of the uplink signal from the terminal device by itself and calculates the amount of interference of the uplink signal. Further, exchange of OI information between base stations is performed using an X2 line.

  The calculation of OI may be performed for each frequency band as in the case of measuring the amount of interference of the downlink signal, or may be further divided into each frequency band, for example, in units of resource blocks. A plurality of threshold values may be set, and the number of OI bits may be a plurality of bits. FIG. 14 shows an example of the definition of OI. FIG. 14A shows a method in which one threshold value is provided and defined in resource block units. FIG. 14B shows a method in which one threshold is provided and one OI is defined for the entire frequency band. FIG. 14C shows a method in which two threshold values are provided and defined in resource block units. In this case, the number of bits required for OI is 2 bits per resource block. FIG. 14D shows a method in which a plurality of threshold values are provided and defined in resource block units.

Next, the power control of the terminal device in the embodiment of the present invention is expressed by the following equation. The power P of the terminal device is determined by the following equation based on parameters instructed by the network.
P = min (Pmax, b * 10logM + Po + αPL + c * delta_mcs + f (delta_i))
Here, b and c are coefficients determined for each frequency band used. When multiple frequency bands are used, the propagation loss differs for each frequency band. For example, when a high frequency is used, propagation loss generally increases, so that interference with other cells is reduced even if power is increased. In the present invention, it is possible to set an appropriate power for reducing interference by considering a propagation loss that differs for each frequency band.

  FIG. 15 is a diagram illustrating another example of interference reduction in the embodiment of the present invention. Base station apparatus BS1101 communicates with terminal apparatus UE1100, base station apparatus BS1101 communicates with terminal apparatus UE1101, and base station apparatus BS1102 communicates with terminal apparatus UE1102. When downlink OI occurs, the base station apparatus performs soft frequency reuse only for communication with the terminal apparatus at the inner edge of the cell with respect to the frequency band in which the OI occurs, or a terminal giving interference Interference is reduced by suspending transmission with the apparatus over all frequency bands, suspending communication only in the frequency band in which OI occurs, or communicating with reduced power.

  FIG. 16 is a diagram illustrating a downlink signal interference reducing method in communication with a plurality of base stations when communication is performed simultaneously from a plurality of base station apparatuses to one terminal apparatus according to another embodiment of the present invention. . Base station apparatus BS1200 communicates with terminal apparatus UE1200. At the same time, the base station apparatus BS1202 communicates with the terminal apparatus UE1200 via the relay station Relay1200. That is, simultaneous communication with two base station apparatuses is performed for terminal apparatus UE1200. When simultaneous communication is performed, a signal from an adjacent cell used for simultaneous communication is not an interference factor but a gain increase factor.

  FIG. 17 is a flowchart showing the processing of the communication system at this time. In the embodiment of the present invention, assuming that one base station is a service BS and the other is an adjacent BS, each base station apparatus first transmits a channel state (CSI: Channel State Information) of a downlink signal reported from a terminal apparatus in each cell. Is measured (Step S300). Next, the base station apparatus serving as the service BS determines whether or not the terminal apparatus is in the simultaneous communication mode (Step S301). If the terminal apparatus is in the simultaneous communication mode, the base station apparatus of the service BS and the base station apparatus of the adjacent BS each set an interference amount. Measure (Step S302), and calculate OI, HII, and TLI for each frequency band (Step S303). Each piece of calculated information is exchanged with other base stations via the X2 line according to the load (Step S304). The base station apparatus that has received the information determines an interference reduction method according to the received information, and sets a radio resource management (RRM) parameter as a coupling parameter between cells based on the method (Step S305). Each base station apparatus exchanges the set combined RRM parameter (Step S306), and each base station apparatus notifies the terminal apparatus of the RRM information based on the combined RRM parameter (Step S307). The base station apparatus continues to set the power control amount, power distribution, bit arrangement, and transmission method (Step S308), and transmits a signal to the terminal apparatus (Step S309). Further, the base station apparatus determines whether to perform transmission to the terminal apparatus to another cell based on the information from the exchanged other cell (Step S310). Thereafter, the terminal apparatus performs feedback of CSI information for the base station apparatus (Step S311).

  FIG. 18 is a diagram illustrating an interference reduction method for uplink signals in communication with a plurality of base stations when communication is performed simultaneously from one terminal device to a plurality of base station devices, which is another embodiment of the present invention. Base station apparatus BS1300 communicates with terminal apparatus UE1300. Similarly, base station apparatus BS1301 communicates with terminal apparatus UE1301, and base station apparatus BS1302 communicates with terminal apparatus UE1302. Since the cell of base station apparatus BS1300 and base station apparatus BS1302 use the same frequency band BW1, OI has occurred. Since base station apparatus BS1301 uses another frequency band BW2, there is no occurrence of OI between base station apparatus BS1300 and Noma.

  FIG. 19 is a flowchart showing the processing of the communication system at this time. When one base station is a service BS and the other is an adjacent BS, each base station apparatus first measures the channel state (CSI: Channel State Information) of the uplink signal in each cell (Step S400). Next, the base station apparatus serving as the service BS determines whether or not the terminal apparatus is in the simultaneous communication mode (Step S401). If it is not in the simultaneous communication mode, the base station apparatus of the service BS and the base station apparatus of the adjacent BS each set an interference amount. Measure (Step S402), and calculate OI, HII, and TLI for each frequency band (Step S403). Each piece of calculated information is exchanged with other base stations through the X2 line according to the load (Step S404). The base station apparatus that has received the information determines an interference reduction method according to the received information, and sets parameters for radio resource management (RRM) based on the method (Step S405). Each base station apparatus exchanges the set RRM parameters (Step S406), and each base station apparatus notifies the terminal apparatus of the RRM information based on the RRM parameters (Step S407). The base station apparatus continues to set the power control amount, power distribution, bit arrangement, and transmission method (Step S408), and the terminal apparatus transmits a signal (Step S409). Further, the terminal device that has received the signal determines whether or not to transmit an uplink signal based on the information (Step S410). Thereafter, the terminal apparatus performs feedback of CSI information for the base station apparatus (Step S411).

  In the simultaneous communication mode, the base station apparatus of the service BS and the base station apparatus of the neighboring BS that performs cooperative communication measure the amount of interference (Step S412), and calculate OI, HII, and TLI for each frequency band. (Step S413). Each piece of calculated information is exchanged with other base stations via the X2 line according to the load (Step S414). The base station apparatus that has received the information determines an interference reduction method according to the received information, and sets a radio resource management (RRM) parameter as a coupling parameter based on the method (Step S415). Each base station apparatus exchanges the set combined RRM parameter (Step S416), and based on the combined RRM parameter, the base station apparatus notifies the terminal apparatus of combined RRM information (Step S417). The base station apparatus continues to set the power control amount, power distribution, bit arrangement, and transmission method (Step S418), and the terminal apparatus transmits a signal (Step S419). Thereafter, the terminal apparatus performs feedback of CSI information for the base station apparatus (Step S420).

  FIG. 20 is a diagram showing the configuration of the base station apparatus according to the present invention. The base station apparatus includes a transmission / reception unit 21, a measurement unit 22, a cooperative mode determination unit 23, a signal processing unit 24, an information exchange unit 25, an RRM unit 26, and an execution unit 27.

  The transmission / reception unit 21 transmits a downlink signal to the terminal device and receives an uplink signal from the terminal device. It also receives interference signals from other cells. The measurement unit 22 measures the signal received by the transmission / reception unit 21 and measures the channel status reported from the terminal device. It also measures the amount of interference from other cells. The cooperative mode determination unit 23 determines whether the terminal device is performing cooperative communication. The signal processing unit 24 performs down-conversion, sampling, channel estimation, demodulation, data detection, transmission signal modulation, up-conversion, and the like of the received signal. The information exchange unit 25 exchanges OI, HII, TLI, a frequency band identifier, a cell identifier, etc. with other cells through an X2 line or a radio line. The RRM unit 26 performs scheduling, resource block arrangement, interference reduction method determination, power control method determination, transmission mode determination, and the like. The execution unit 27 performs power control and overall operation control.

  FIG. 21 is a diagram showing the configuration of the terminal device according to the present invention. The terminal device includes a transmission / reception unit 31, a signal processing unit 32, a scheduling unit 33, and an execution unit 34. The transmission / reception unit 31 receives a signal from the base station apparatus. The signal processing unit 32 performs down-conversion, sampling, channel estimation, demodulation, data detection, transmission signal modulation, up-conversion, and the like of the received signal. The scheduling unit 33 analyzes the scheduling information sent from the transmission device, and manages the reception and transmission with the allocated resources. The execution unit 34 performs overall operation control of power control.

  FIG. 22 is a diagram showing a system configuration in the present invention. The interference reduction system includes a transmission / reception unit 50, a plurality of frequency band adjustment units 51, a back howl interface 52, an RRM unit 53, and a radio interface 54. The transmission / reception unit 50 transmits / receives signals. The multiple frequency band adjustment unit adjusts which frequency band is used when using multiple frequency bands. The backhaul interface 52 performs OI, HII, TLI, frequency band identifier, cell identifier, data exchange when performing plural cooperative communication, and the like. The RRM unit 53 performs radio resource management such as a schedule. The wireless interface 54 is used in cities that perform the same role as the X2 interface.

  By using the system described above, it is possible to effectively make interference proposals in the present invention.

  In the above-described embodiment, the configuration and the like illustrated in the accompanying drawings are not limited to these, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention. For example, in the description of the present invention, interference with adjacent cells has been described. However, the present invention is not limited to this and includes interference with adjacent cells of adjacent cells. It can also be applied to multi-hop systems such as relay stations and remote radio transmission stations.

  In addition, a program for realizing the functions described in the present embodiment is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed to execute processing of each unit. May be performed. The “computer system” here includes 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” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time, like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case is also used to hold a program for a certain period of time. The program may be a program for realizing a part of the above-described functions, or may be a program that can realize the above-described functions in combination with a program already recorded in a computer system.

DESCRIPTION OF SYMBOLS 21 ... Transmission / reception part, 22 ... Measurement part, 23 ... Cooperative mode determination part, 24 ... Signal processing part, 25 ... Information exchange part, 26 ... RRM part, 27 ... Execution part, 31 ... Transmission / reception part, 32 ... Signal processing part, 33 ... Scheduling unit, 34 ... execution unit, 50 ... transmission / reception unit, 51 ... multiple frequency band arbitration unit, 52 ... back howl interface, 53 ... RRM unit, 54 ... wireless interface

Claims (15)

  A wireless communication system that performs communication using a plurality of frequency bands, wherein a plurality of base station devices in the communication system simultaneously communicate with one terminal device, or a plurality of base station devices communicate with one terminal device. In a coordinated multi-base station communication system that performs timing arbitration, the base station apparatus that performs the multi-base station communication measures means for measuring interference, means for measuring traffic in a cell, the amount of interference and the traffic And a means for exchanging cell identifiers and frequency band identifiers between base stations according to the state of traffic in the cell, means for determining an interference arbitration scheme from the exchanged information, and based on the determined interference arbitration scheme Means for performing radio resource management setting, and means for notifying information of the radio resource management setting to a terminal device in each cell, the terminal The apparatus includes a means for determining whether to perform transmission / reception based on the notified information of the radio resource management setting.   The interference amount measurement performed by the base station apparatus that performs the multiple base station communication is performed independently by each base station, and the interference amount measurement is performed by measuring the downlink interference amount for each terminal device or the downlink amount for each cell. The wireless communication system according to claim 1, wherein one or more of interference amount measurement or uplink interference amount measurement for each cell is performed.   The downlink interference amount measurement for each terminal device is performed by measuring an overload index and a frequency band identifier for each downlink resource block, an overload index for each downlink frequency band, or an overload index and a frequency band for each downlink resource block using a plurality of bits. The wireless communication system according to claim 2, wherein one or a plurality of identifiers or an overload index for each downlink frequency band using a plurality of bits is used.   The downlink interference amount measurement for each cell is an overload indicator and frequency band identifier for each downlink resource block, or an overload indicator for each downlink frequency band, or an overload indicator and frequency band identifier for each downlink resource block using a plurality of bits. The wireless communication system according to claim 2, wherein the wireless communication system is performed for one or a plurality of overload indicators for each downlink frequency band using a plurality of bits.   The uplink interference amount measurement for each cell is performed using an overload indicator and frequency band identifier for each uplink resource block, or an overload indicator for each uplink frequency band, or an overload indicator and frequency band identifier for each uplink resource block using a plurality of bits. The wireless communication system according to claim 2, wherein the wireless communication system is performed for one or a plurality of overload indices for each uplink frequency band using a plurality of bits.   The radio communication system according to claim 1, wherein the interference arbitration method is partial frequency reuse or soft frequency reuse when the terminal apparatus performs multi-base station communication.   The radio communication system according to claim 1, wherein the interference arbitration method assigns different frequency bands to terminal devices at different cell edges when the terminal device does not perform communication with a plurality of base stations.   The said interference arbitration system allocates a different frequency band with respect to the terminal device which performs multiple base station communication in a different cell, and the terminal device which does not perform multiple base station communication. Wireless communication system.   The notification of the radio resource management setting information to a terminal device in each cell is performed using one or more of a broadcast channel, a downlink control channel, or a downlink shared channel. Item 2. The wireless communication system according to Item 1.   The radio communication according to claim 1, wherein the determined interference arbitration method and the determined radio resource management setting are determined according to a capability related to a frequency band that can be used by a terminal apparatus. system.   The interference arbitration method is a frequency division interference arbitration method using downlink power control in a heterogeneous base station network, a downlink frequency division interference arbitration method in the same type base station network, or a downlink transmission stop method for each frequency band, or a frequency band The wireless communication system according to claim 1, wherein one or more of a plurality of base station communication systems for each frequency band or an uplink transmission system for each frequency band are used.   A wireless communication system that performs communication using a plurality of frequency bands, wherein a plurality of base station devices in the communication system simultaneously communicate with one terminal device, or a plurality of base station devices communicate with one terminal device. A base station apparatus used in a coordinated multiple base station communication system that performs timing arbitration, the means for measuring an interference amount, the means for measuring traffic in a cell, the interference amount, the traffic, and a cell identifier And means for exchanging frequency band identifiers between base stations according to the traffic state in the cell, means for determining an interference arbitration scheme from the exchanged information, and radio resource management based on the determined interference arbitration scheme Means for performing setting, and means for notifying information on the radio resource management setting to a terminal device in each cell. Base station device.   A wireless communication system that performs communication using a plurality of frequency bands, wherein a plurality of base station devices in the communication system simultaneously communicate with one terminal device, or a plurality of base station devices communicate with one terminal device. A terminal device used in a coordinated multiple base station communication system that performs timing arbitration, and has means for determining whether to perform transmission / reception based on radio resource management setting information notified from the base station device. A terminal device that communicates with the base station device according to Item 12.   A wireless communication system that performs communication using a plurality of frequency bands, wherein a plurality of base station devices in the communication system simultaneously communicate with one terminal device, or a plurality of base station devices communicate with one terminal device. A control method in a base station apparatus used in a coordinated multi-base station communication system that performs timing arbitration, the step of measuring an amount of interference, the step of measuring traffic in a cell, the amount of interference and the traffic And a step of exchanging cell identifiers and frequency band identifiers between base stations according to the traffic state in the cell, a step of determining an interference arbitration scheme from the exchanged information, and based on the determined interference arbitration scheme A step of performing radio resource management setting, and notifying information of the radio resource management setting to a terminal device in each cell A control method comprising the steps of:   A program for causing a computer to execute the method according to claim 14.