JP5774583B2 - Method for estimating channel state in wireless communication system using partial frequency reuse method and terminal device using the same - Google Patents

Description

  The present invention relates to a radio communication system, and more particularly, to a method for estimating a channel state in a radio communication system using an FFR scheme.

  Frequency reuse is one way to increase the number of channels per unit area in a cellular system. In general, the strength of radio waves gradually decreases with increasing distance, and there is less interference between radio waves at a distance of a certain distance or more, so the same frequency channel can be used. Using this principle, the subscriber capacity can be greatly increased by simultaneously using the same frequency in many areas. This efficient use of frequency is called frequency reuse.

  A unit for dividing a region is called a cell (or sector), and frequency channel switching between cells for maintaining a call is called handoff. In the analog cellular mobile communication system, a frequency reuse technique is essential. The frequency reuse factor is one of the parameters indicating the frequency efficiency in the cellular system. The frequency reuse rate is a value obtained by dividing the total number of cells (sectors) that simultaneously use the same frequency in the multiple cell structure by the total number of cells (sectors) in the entire multiple cell structure.

  The frequency reuse rate of a 1G system (for example, AMPS (Advanced Mobile Phone Service)) is smaller than 1. For example, in 7-cell frequency reuse, the frequency reuse rate is 1/7. The frequency reuse rate of 2G systems (for example, Code Division Multiple Access (CDMA) and Time Division Multiple Access (TDMA)) has improved compared to 1G. For example, the frequency reuse rate in GSM (Global System for Mobile communications) in which FDMA (Frequency Division Multiple Access) and TDMA are combined can reach ¼ to ３. For 2G CDMA systems and 3G WCDMA (Wide Code Division Multiple Access) systems, the frequency reuse factor can reach unity, thus increasing spectrum efficiency and reducing network deployment costs.

  When all sectors in one cell and all cells in one network use the same frequency, a frequency reuse factor of 1 can be obtained. However, in the case of a system with a frequency reuse factor of 1, interference between adjacent cells is severe at the cell or sector boundary, and a reduction in throughput is unavoidable, and there is a risk of facing an outage situation. is there. That is, at the cell boundary, it means that the signal reception performance decreases due to interference from adjacent cells.

  In OFDMA (Orthogonal Frequency-Division Multiple Access), since channels are separated in units of subchannels, signals are transmitted on the subchannels, and all channels are not used as in 3G (CDMA2000 or WCDMA). By utilizing such a feature, it is possible to simultaneously improve the throughput of the user located at the center of the cell and the user located at the cell boundary.

  Specifically, since the central region of the cell is close to the base station, it is safer against co-channel interference from neighboring cells. Thus, the internal user located in the center of the cell can use all available secondary channels. However, the user located at the cell boundary can use only a part of all the available subchannels. At cell boundaries adjacent to each other, frequencies are allocated so that each cell uses a different subchannel. Such a method is referred to as FFR (Fractional Frequency Reuse). A common channel between adjacent cells by orthogonally dividing the entire subcarrier into a number of frequency partitions, arranging these frequency partitions appropriately and not using some frequency partitions in each cell or using them at low power Interference can be mitigated.

  Recently, a multiple input multiple output (MIMO) system has attracted attention as a broadband wireless mobile communication technology. A MIMO system refers to a system that uses a large number of antennas to increase data communication efficiency. The MIMO system can be implemented using MIMO schemes such as a spatial multiplexing technique and a spatial diversity technique depending on whether or not the same data transmission is possible.

  Spatial multiplexing technique refers to a scheme that allows data to be transmitted at high speed without increasing the system bandwidth by simultaneously transmitting different data via a number of transmission antennas. Spatial diversity technique refers to a scheme in which the same data can be transmitted by multiple transmission antennas to obtain transmission diversity. One example of such a spatial diversity technique is space-time channel coding.

  The MIMO technology can be classified into an open loop method and a closed loop method depending on whether or not channel information is fed back from the reception side to the transmission side. In the open loop method, information is transmitted in parallel from the transmitting end, and at the receiving end, signals are detected by repeatedly using ZF (Zero Forcing) and MMSE (Minimum Mean Square Error) methods, and information is transmitted by the number of transmitting antennas. There are blast (BLAST) that can increase the amount, and STTC (Space-Time Trellis Code) that can obtain transmission diversity and coding gain by using a new spatial region. A closed loop system includes a TxAA (Transmit Antenna Array) system.

  In the wireless channel environment, a fading phenomenon occurs in which the channel state changes irregularly in the time domain and the frequency domain. Therefore, the receiver corrects the received signal using the channel information in order to restore the data transmitted from the transmitter and detect a correct signal. The wireless communication system transmits a signal known to both the transmitter and the receiver, and detects channel information using the degree of distortion when the signal is transmitted through the channel. This is called a signal (or pilot signal), and detecting channel information is called channel estimation. The reference signal does not actually contain data and has a high output. When data is transmitted / received using multiple antennas, the channel condition between each transmission antenna and reception antenna should be known, so there is a reference signal for each transmission antenna.

  Coordinated Multi-Point (CoMP) system (hereinafter referred to as CoMP system) is proposed to reduce inter-cell interference in a multi-cell environment and improve terminal performance at the cell boundary. is there. That is, when the CoMP system is used, the communication performance of the terminal at the cell boundary can be improved in a multi-cell environment. For this purpose, accurate channel estimation based on reference signals from multiple base stations is required. When the CoMP system is used, terminals can receive data support jointly from base stations of multiple cells. At this time, each base station can simultaneously support one or more terminals (MS1, MS2,..., MSK) using the same frequency resource in order to improve system performance. Further, the base station can perform a space division multiple access (SDMA) method based on channel state information between the base station and the terminal.

  A serving base station and one or more cooperating base stations in a CoMP system are connected to a scheduler via a backbone network. The scheduler provides feedback of channel information regarding the channel state between each terminal (MS1, MS2,..., MSK) measured by each base station (BS1, BS2,..., BSM) and the cooperating base station via the backbone network. Can receive and operate. For example, the scheduler schedules information for cooperative MIMO operation to the serving base station and one or more cooperative base stations. That is, an instruction for cooperative MIMO operation is directly given from the scheduler to each base station.

  FIG. 1 is a diagram conceptually illustrating CoMP of an existing intra base station (intra eNB) and an inter base station (inter NB).

  Referring to FIG. 1, there are intra base stations 110 and 120 and an inter base station 130 in a multi-cell environment. An intra base station in LTE (Long Term Evolution) is composed of several cells (or sectors). Each cell belonging to the base station to which the specific terminal belongs has a relationship between the specific terminal and the intra base stations 110 and 120. That is, each cell sharing a base station such as a cell to which a terminal belongs is a cell corresponding to the intra base stations 110 and 120, and each cell belonging to another base station is a cell corresponding to the inter base station 130. It is. In this way, each cell based on the same base station as the specific terminal exchanges information (for example, data, channel state information) via the x2 interface, etc., but each cell based on another base station Inter-cell information can be exchanged via the backhaul 140 or the like.

  As shown in FIG. 1, a single cell MIMO user 150 located in a single cell communicates with one serving base station in one cell (sector), and a multi-cell MIMO user 160 located at a cell boundary It can communicate with multiple serving base stations in multiple cells (sectors).

  As described above, the terminal performs a CoMP operation that cooperatively operates between base stations (or cells) in a multi-cell environment. However, when CoMP operation is performed using the FFR scheme in a multi-cell environment, a method for efficiently estimating the interference of neighboring cells for improving the performance of the terminal at the cell boundary has not yet been proposed.

  A technical problem to be achieved by the present invention is to provide a method for estimating a channel state in a wireless communication system using a fractional frequency reuse (FFR) scheme.

  Another technical problem to be achieved by the present invention is to provide a terminal device that estimates a channel state in a radio communication system using the FFR scheme.

  Each technical problem to be achieved by the present invention is not limited to the above technical problem, and other technical problems not mentioned are those having ordinary knowledge in the technical field to which the present invention belongs from the following description. Will be clearly understood.

  In order to achieve the above technical problem, the channel state estimation method according to the present invention is such that a terminal acquires cell ID (Identifier) information from a serving cell and one or more neighboring cells; Obtaining preset power level pattern information for one or more frequency partitions to which the FFR scheme is applied; and using the obtained power level pattern information to set a channel state for the serving cell. Estimation may be included.

  The method further includes receiving a boosting power level value from the serving cell for a frequency partition on which power boosting of the serving cell has been performed, wherein the acquired power level is estimated to estimate the channel state. A channel state may be estimated for the serving cell and / or one or more neighboring cells using pattern information and a boosting power level value for a frequency partition on which power boosting of the received serving cell is performed. .

  The method further includes receiving a boosting power level value for a frequency partition for which power boosting of the one or more neighboring cells is performed from the one or more neighboring cells, wherein the channel state is estimated. For example, the one or more neighboring cells using the acquired power level pattern information and the boosting power level value for the frequency partition on which the power boosting of the received one or more neighboring cells is performed. Can be estimated.

  Further, the method may further include feeding back channel state information generated based on the estimated channel state to the serving cell.

  A terminal apparatus according to the present invention for solving the other technical problem includes a cell ID acquisition module for acquiring cell ID information from a serving cell and one or more neighboring cells; an FFR scheme corresponding to each acquired cell ID. A power level pattern information acquisition module for acquiring power level pattern information set in advance for one or more frequency partitions to which is applied; and a channel for the serving cell using the acquired power level pattern information. A channel state estimation module that estimates the state may be provided.

  The serving cell boosting power level value receiving module may further receive a boosting power level value for a frequency partition for which the serving cell power boosting has been performed from the serving cell. The serving cell and / or the one or more neighboring cells using the acquired power level pattern information and the boosting power level value for the frequency partition on which the power boosting of the received serving cell is performed. The channel state can be estimated.

In addition, a boosting power level value receiving module for a neighboring cell that receives a boosting power level value for a frequency partition in which power boosting of the one or more neighboring cells has been performed from the one or more neighboring cells is further provided. In this case, the channel state estimation module uses the acquired power level pattern information and the boosting power level value for the frequency partition where the power boosting of the received neighboring cell is performed. The channel state of the above adjacent cell can be estimated.
This specification provides the following items, for example.
(Item 1)
In a method for estimating a channel state in a wireless communication system using a fractional frequency reuse (FFR) scheme,
The terminal obtains cell ID information from the serving cell and one or more neighboring cells;
Obtaining power level pattern information set in advance for one or more frequency partitions to which an FFR scheme corresponding to each obtained cell ID is applied; and
A channel state estimation method comprising estimating a channel state for the serving cell using the acquired power level pattern information.
(Item 2)
Receiving from the serving cell a boosting power level value for a frequency partition on which power boosting of the serving cell has been performed;
The channel state estimation may be performed using the acquired power level pattern information and the boosting power level value for the frequency partition on which the received serving cell power boosting is performed, and / or 2. The channel state estimation method according to item 1, wherein the channel state is estimated for two or more adjacent cells.
(Item 3)
Receiving the boosting power level value for the frequency partition on which power boosting of the one or more neighboring cells is performed from the one or more neighboring cells, and estimating the channel state comprises: The channel state of the one or more neighboring cells is estimated using the acquired power level pattern information and the received boosting power level value for the frequency partition where the power boosting of the one or more neighboring cells is performed. The channel state estimation method according to item 1, wherein:
(Item 4)
The channel state estimation method according to item 1, further comprising feeding back channel state information generated based on the estimated channel state to the serving cell.
(Item 5)
The preset power level pattern information includes information indicating a frequency partition set to boosting or non-boosting among one or more frequency partitions to which the FFR scheme is applied. The described channel state estimation method.
(Item 6)
6. The channel state estimation method according to item 5, wherein the frequency partition set to boosting or non-boosting is displayed as an index.
(Item 7)
The channel state estimation method according to item 1, wherein the preset power level pattern is determined by a cell ID function value of the serving cell and the one or more neighboring cells.
(Item 8)
8. The channel state estimation method according to item 7, wherein the cell ID function value is determined by a value of (cell ID modulus 1 / partial frequency reuse rate).
(Item 9)
The channel state estimation method according to Item 1, wherein the cell ID information corresponds to one of physical cell ID information and global cell ID information.
(Item 10)
4. The boosting power level value of the boosted frequency partition of the one or more neighboring cells is set to be different from the boosting power level value of the boosted frequency partition of the serving cell. Channel state estimation method.
(Item 11)
The channel state estimation method according to item 2, wherein the boosting power level value of the boosted frequency partition of the serving cell is a quantized value.
(Item 12)
The channel state estimation method according to item 3, wherein the boosting power level value of the boosted frequency partition of the one or more neighboring cells is a quantized value.
(Item 13)
In a terminal device that estimates a channel state in a wireless communication system that uses a fractional frequency reuse (FFR) scheme,
A cell ID acquisition module for acquiring cell ID information from the serving cell and one or more neighboring cells;
A power level pattern information acquisition module for acquiring power level pattern information preset for one or more frequency partitions to which the FFR scheme corresponding to each acquired cell ID is applied; and
A terminal apparatus comprising a channel state estimation module for estimating a channel state for the serving cell using the acquired power level pattern information.
(Item 14)
A serving cell boosting power level value receiving module for receiving a boosting power level value for a frequency partition for which power boosting of the serving cell has been performed from the serving cell;
The channel state estimation module uses the acquired power level pattern information and the boosting power level value for the frequency partition where the received power boosting of the serving cell is performed, to the serving cell and / or the one or more. Item 14. The terminal device according to Item 13, wherein a channel state is estimated for a neighboring cell.
(Item 15)
Further comprising: a neighboring cell boosting power level value receiving module receiving a boosting power level value for a frequency partition where power boosting of the one or more neighboring cells is performed from the one or more neighboring cells;
The channel state estimation module uses the acquired power level pattern information and the boosted power level value for the frequency partition on which the received power boosting of the neighboring cell is performed, for the one or more neighboring cells. Item 14. The terminal device according to Item 13, wherein the channel state is estimated.

  According to the present invention, the UE can accurately and efficiently estimate the channel state for each cell performing CoMP operation using the FFR scheme.

  The effects obtained by the present invention are not limited to the effects mentioned above, and other effects not mentioned are clearly understood by those having ordinary knowledge in the technical field to which the present invention belongs from the following description. right.

It is the figure which showed notionally CoMP of the existing intra base station (intra eNB) and an inter base station (inter eNB). It is a figure for demonstrating each physical channel used for 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) system which is an example of a mobile communication system, and the general signal transmission method using these. It is the figure which showed an example in which a specific terminal receives service from one or more base stations by the position in a cell in a multi-cell environment. It is the figure which showed the structural example of the hard FFR applicable when performing a CoMP operation | movement using a FFR system in a multicell environment. It is the figure which showed an example of the soft FFR structure applicable when performing CoMP operation | movement using a FFR system in a multicell environment. It is the figure which showed the other example of the soft FFR structure applicable when performing CoMP operation | movement using a FFR system in a multicell environment. It is the figure which showed an example of the downlink frame structure of a frequency division duplex (FDD: Frequency Division Duplex) form in 3GPP LTE system which is an example of a mobile communication system. It is the figure which showed the Example of the suitable structure of the terminal device which concerns on this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description disclosed below in connection with the appended drawings is intended as a description of exemplary embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, one skilled in the art will know that the present invention may be practiced without such specific details. For example, the following detailed description will be specifically described assuming that the mobile communication system is a 3GPP LTE system, but the mobile communication system can be applied to any other mobile communication system except for the specific matters of 3GPP LTE. Applicable.

  In some instances, well-known structures and devices may be omitted or may be illustrated in block diagram form with the core functions of each structure and device centered on to avoid obscuring the concepts of the present invention. . In addition, the same constituent elements will be described using the same reference numerals throughout the present specification.

  In addition, in the following description, it is assumed that the terminal (or user equipment) generically refers to a mobile or fixed type user end equipment such as a UE (User Equipment), an MS (Mobile Station), or the like. Further, it is assumed that the base station generically refers to any node at the end of the network that communicates with a terminal such as Node B, eNode B, Base Station, and the like.

  In a mobile communication system, a terminal can receive information from a base station through a downlink, and the terminal can transmit information through an uplink. Information transmitted or received by the terminal includes data and various control information, and various physical channels exist depending on the type and use of information transmitted or received by the terminal.

  FIG. 2 is a diagram for explaining each physical channel used in 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) system, which is an example of a mobile communication system, and a general signal transmission method using them. is there.

  As shown in FIG. 2, a terminal that is turned on again after the power is turned off or newly enters the cell performs an initial cell search operation such as synchronizing with the base station in step S201. For this purpose, the terminal synchronizes with the base station by receiving a primary synchronization channel (P-SCH) and a secondary synchronization channel (S-SCH) from the base station, cell ID, etc. Information can be acquired. Thereafter, the terminal can acquire the broadcast information in the cell by receiving the physical broadcast channel from the base station. Meanwhile, the UE can check the downlink channel state by receiving a DLRS (Downlink Reference Signal) at the initial cell search stage.

  In step S202, the UE that has completed the initial cell search uses a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) corresponding to the physical downlink control channel information. By receiving it, more specific system information can be acquired.

  On the other hand, when the terminal is first connected to the base station or there is no radio resource for signal transmission, the terminal can perform an arbitrary connection process such as steps S203 to S206 to the base station. For this purpose, the terminal transmits a specific sequence as a preamble through a physical random access channel (PRACH) (S203), and transmits a response message for the arbitrary connection through the PDCCH and the corresponding PDSCH. It can be received (S204). In the case of an arbitrary connection based on competition except for the case of handover, the terminal may perform a contention resolution procedure such as transmission of additional PRACH (S205) and reception of PDCCH / PDSCH (S206). it can.

  After performing the above-described procedure, the terminal then performs PDCCH / PDSCH reception (S207) and physical uplink shared channel (PUSCH) / physical uplink control channel as a general uplink / downlink signal transmission procedure. (PUCCH: Physical Uplink Control Channel) transmission (S208) can be performed. At this time, the control information transmitted from the terminal to the base station through the uplink or received from the base station by the terminal includes a downlink / uplink ACK / NACK signal, CQI (Channel Quality Indicator) / PMI (Precoding Matrix Index). ) / RI (Rank Indicator). In the case of a 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) system, the terminal can transmit control information such as CQI, PMI, and RI described above via PUSCH and / or PUCCH.

  The term base station used in the present invention can be referred to as a cell or sector when used in a regional concept. A serving base station (or cell) can be regarded as a base station that provides an existing main service to a terminal, and can perform transmission / reception of control information on a coordinated multiple transmission point. In this sense, the serving base station (or cell) can be referred to as an anchor base station (or cell). Similarly, neighboring base stations can be referred to as neighboring cells used in regional concepts. A cell or sector is used to refer to a basic network element that operates FFR. From the viewpoint of providing services to terminals on a cell boundary by operating FFR, these cells or sectors may be referred to as a mixture. it can.

  If the CoMP scheme is used in a multi-cell environment, the communication performance of the terminal at the cell boundary can be improved. Such a CoMP scheme reduces joint interference (JP: Joint Processing) through data sharing, inter-cell interference such as worst companion (best companion) and best companion (best companion). Cooperative scheduling / beamforming (CS / CB: Coordinated Scheduling / Beamforming) method. Here, in the worst companion scheme, the terminal reports the PMI with the largest interference to each serving cell to the serving base station, so that the corresponding cell uses the suboptimal PMI excluding the corresponding PMI. This is an interference removal method. The best companion method is an inter-cell interference reduction method in which the corresponding cell uses the corresponding PMI by reporting the PMI with the least interference to each cell in which the terminal performs CoMP. Such a CoMP scheme can be used to include a communication scheme in which a serving base station and an adjacent base station operate cooperatively in a multi-cell based environment.

  In order to apply partial frequency reuse (FFR) in a multi-cell environment, each base station can use different frequency bands (or frequency partitions) on the secondary channel. However, since some tones are used by all sectors, the frequency reuse factor is 1. On the other hand, since only 1/3 of other tones are used by each sector, the frequency reuse factor is 1/3. Such a frequency reuse rate can be variously set according to network settings. As the FFR method, there are a hard FFR method and a soft FFR method. In the hard FFR system, some tones are not used at all. On the other hand, in the soft FFR method, some tones are used with low power. As described above, the FFR can be variously configured according to the setting, and can be a method for effectively reducing interference between multiple cells. Therefore, in order to effectively operate the FFR in actual application, information regarding the configuration of the FFR must be shared between each base station and / or each terminal.

  In particular, in the case of the soft FFR scheme, the terminal needs to know the transmission power of each frequency band (or frequency partition) in measuring CQI (channel quality index) based on signals received from multiple cells. That is, in order to efficiently perform CoMP (particularly Coordinated Scheduling) operation using the FFR scheme under a multi-cell infrastructure, it is necessary to estimate information such as interference levels of neighboring cells.

  For each user located at a cell boundary, signal reception performance is reduced due to interference from adjacent cells. The multi-cell based FFR can improve the performance of the terminal at the cell boundary by reducing the interference caused by the adjacent cells. Such multi-cell based FFR can be considered as one category of cooperative scheduling / beamforming (CS / CB) in a CoMP system.

  In an environment using a multi-cell-based FFR scheme, each cell performing FFR boosts or non-boosts a specific frequency band, thereby reducing inter-cell interference over cell boundary terminals using the specific frequency band. Can be made.

  FIG. 3 is a diagram illustrating an example in which a specific terminal receives services from one or more base stations according to a position in a cell in a multi-cell environment.

  Referring to FIG. 3, terminal a receives a service from cell A as a terminal belonging to the boundary of cell A, but is affected by cell B because it belongs to the boundary of cell B. Similarly, the terminal b receives a service from the cell B as a terminal belonging to the boundary of the cell B, but is affected by the cell A because it belongs to the boundary of the cell A. The terminal c1 receives a service from the cell C as a terminal belonging to the boundary of the cell C. However, since the terminal c1 belongs to the boundary of the cell B, the terminal c1 is affected by the cell B. Although the terminal c2 receives a service from the cell C as a terminal belonging to the boundary of the cell C, the terminal c2 is affected by the adjacent cell because it belongs to the boundary of another cell (not shown). The terminal d receives service from the cell D as a terminal belonging to the boundary of the cell D. However, since the terminal d belongs to the boundary of the cell B and the cell C, the terminal d is affected by the cell B and the cell C.

  That is, terminals a, b, c1, c2 and d are simultaneously affected by neighboring cells as terminals belonging to the boundary of at least two cells. Therefore, the data processing amount of the received service is reduced due to co-channel interference by neighboring cells. On the other hand, internal users are not affected by neighboring cells.

  FIG. 4 is a diagram illustrating a configuration example of a hard FFR that can be applied when a CoMP operation is performed using the FFR scheme in a multi-cell environment.

  Referring to FIG. 4, the total frequency resources available to a cell can be partitioned / classified according to various criteria in connection with FFR application. First, the total frequency band (or partition) that can be used by each cell can be roughly divided into two regions. The first area is a frequency band for a boundary user (boundary terminal) located at the boundary with an adjacent cell, and the second area is a frequency band for an internal user (internal terminal) of the cell.

  In the FFR scheme, the frequency band for border users can be divided into a number of smaller regions. The FFR scheme shown in FIG. 4 illustrates the case of FFR1 / 3 (that is, the frequency reuse rate associated with FFR is 1/3). In the case of FFR1 / 3, the frequency resource for the border user is divided into three regions, and each cell serves the border user using only one of the three regions.

  In the present invention, the frequency resource used by each cell to provide a service to a terminal can be divided into several frequency resource groups. In this case, the specific frequency resource group includes a specific frequency band or a specific frequency partition. It can be called. In addition, the frequency resource group can be classified according to the use associated with FFR. As shown in FIG. 4, the total frequency resource group that can be used by the cell can be classified into three frequency bands according to the application related to FFR.

  For example, with reference to cell A, the first frequency band 410 can be referred to as “FFR_band_edge” as a frequency resource group that is actually used for the boundary user. The second frequency bands 420 and 430 may be referred to as “FFR_band_inner” as a frequency resource group that is not used for the boundary user among the frequency resource groups for the boundary user. The third frequency band 440 may be referred to as “inner_band” as a frequency resource group for internal users.

  Also, as shown in FIG. 4, since each cell uses only 1/3 of the frequency resources allocated for the boundary user, the frequency reuse rate for the cell boundary user is 1/3. is there. On the other hand, since each cell uses all the frequency resources allocated for the internal users, the frequency reuse rate for internal users is one.

  FIG. 5 is a diagram illustrating a configuration example of a soft FFR applicable when a CoMP operation is performed using the FFR scheme in a multi-cell environment.

  Referring to FIG. 5, the total frequency resources allocated to each cell can be divided into four frequency resource groups 510 to 540. Frequency resource group 1 to frequency resource group 3 in each cell correspond to frequency resources 410 to 430 in FIG. 4 as frequency resources for terminals on the cell boundary. The frequency resource group 4 corresponds to 440 in FIG. 4 as a frequency resource group for terminals located inside each cell. Further, the cells A to C shown in FIG. 5 correspond to the cells A to C of FIG.

  An embodiment of the soft FFR illustrated in FIG. 5 is basically similar to the embodiment of the hard FFR illustrated in FIG. However, the soft FFR illustrated in FIG. 5 prevents a decrease in bandwidth efficiency due to an unused frequency resource group (for example, a frequency resource group corresponding to 420 and 430 in the cell A in FIG. 4) in the hard FFR in FIG. be able to. Hereinafter, description will be given by taking the cell A as an example. The total frequency resources that can be used by cell A can be divided into four frequency resource groups. In FIG. 5, frequency resource group 1 to frequency resource group 3 have a frequency reuse rate of 1/3 as a frequency resource group for cell boundary terminals. Therefore, the cell A can provide a service to the terminal at the cell boundary using only one frequency resource group 510 (FFR_band_edge area) among the frequency resource groups 1 to 3. On the other hand, the remaining two frequency resource groups 520 and 530 (FFR_band_inner area) are not used for the terminal at the boundary. In contrast, the frequency resource group 4 has a frequency reuse rate of 1 as the frequency resource group 540 (inner_band region) allocated for the terminals in the cell A.

  Unlike the hard FFR method illustrated in FIG. 4, the cell A to which the soft FFR method is applied in FIG. 5 additionally uses frequency resources (FFR_band_inner) corresponding to the frequency resource group 2 and the frequency resource group 3. The service can be provided to the internal terminal of the cell A. For this reason, the cell A prevents interference with terminals located at the boundary between the cell B and the cell C by setting the power level of the frequency resource corresponding to the frequency resource group 2 and the frequency resource group 3 low. Can do.

  Thus, in the soft FFR method, frequency resources can be grouped and the frequency efficiency can be improved by setting the power level of each group to be different depending on the use of each group.

  In FIG. 5, the power level used by each cell to serve a terminal can be classified into three types (PFFR_band_edge ≧ Pinner_band> PFFR_band_inner) according to the use of the frequency resource group. Here, PFFR_band_edge can be used when providing a service to a terminal located at a cell boundary using a frequency resource group (FFR_band_edge) having a frequency reuse rate of 1/3. PFFR_band_inner can be used when a service is provided to a terminal existing in a cell using a frequency resource group (FFR_band_inner) having a frequency reuse rate of 1/3. Also, Pinner_band can be used when a service is provided using a frequency resource group (inner_band) having a frequency reuse factor of 1 existing inside the cell.

  In order to efficiently operate the soft FFR scheme, it is necessary to set the power level for each frequency resource group, and the base station and / or the terminal must know the power level for each frequency resource group. In particular, in order for the terminal to efficiently perform the CoMP cooperative scheduling (CS) scheme using the FFR scheme on a multi-cell basis, it is necessary to estimate information such as interference levels of neighboring cells. For this reason, if the terminal knows not only the power level for each frequency resource group of the serving cell but also the power level for each frequency resource group of the neighboring cell, it is desirable to estimate the CQI value and the like efficiently.

  In addition, in order to efficiently operate FFR according to user distribution in a cell (or sector), the bandwidth of each frequency resource group allocated for FFR or the composition ratio of each frequency resource group is flexibly adjusted. FFR techniques can be considered. To this end, each base station and / or terminal must know information related to the bandwidth of each frequency resource group or the composition ratio of each frequency resource group.

  Hereinafter, FFR information necessary for the terminal to perform FFR for CoMP in a multi-cell environment will be described.

  The serving base station can inform the terminal that performs FFR for CoMP about the serving cell and / or the frequency resource group boosted in each cell performing CoMP and the non-boosted frequency resource group. At this time, the serving base station can inform the terminal of the boosted frequency resource group and the non-boosted frequency resource group in a bitmap format. In addition, the serving base station can inform the terminal of the boosted frequency resource group index of each cell.

  When the boosting level and the non-boosting level of multiple cells performing FFR are the same, and each power level is determined in advance, the power level can be expressed by an on-off binary code. Then, the serving base station can inform the terminal only of boosting or non-boosting for the frequency resource group of the serving cell and neighboring cells. If all cells performing FFR have the same boosting power level, this value can also be a predefined specific value. In addition, the boosting power level of each cell can be set to the same value as the boosting power level of the serving cell.

  In another method, a pattern according to a boosting power level and a non-boosting power level is preset according to a partial frequency reuse rate (for example, 1/2, 1/3, 1/4,..., 1 / n). Can do. That is, only the FFR boosting level pattern based on the frequency reuse rate set in advance for each cell performing FFR for CoMP can be notified to the terminal. Hereinafter, the FFR boosting level pattern will be described as an example.

  Referring to FIG. 5, the FFR is operating at a partial frequency reuse rate of 1/3. There may be three FFR boosting level patterns as FFR patterns corresponding to the partial frequency reuse rate 1/3. Each cell performing FFR can determine the level of transmission power according to the boosting power level and the non-boosting power level corresponding to one of these patterns.

  Table 1 below shows an example of the FFR boosting level pattern for each cell when the partial frequency reuse rate is 1/3.

Referring to Table 1, the first FFR boosting level pattern is [group 1, group 2, group 3] = [boosting, non-boosting, non-boosting] and the second FFR boosting level pattern. [Group 1, Group 2, Group 3] = [Non-Boosting, Boosting, Non-Boosting] and the third FFR boosting level pattern is [Group 1, Group 2, Group 3] = [Non -Boosting, non-boosting, boosting].

  Table 2 below shows an example of the FFR boosting level pattern for each cell when the partial frequency reuse rate is 1/4.

Referring to Table 2, when the partial frequency reuse rate is 1/4, there may be four FFR boosting level patterns. For example, the first FFR boosting level pattern is [group 1, group 2, group 3, group 4] = [boosting, non-boosting, non-boosting, non-boosting] and the second FFR. The boosting level pattern is [group 1, group 2, group 3, group 4] = [non-boosting, boosting, non-boosting, non-boosting], and the third FFR boosting level pattern is [ Group 1, group 2, group 3, group 4] = [non-boosting, non-boosting, boosting, non-boosting] and the fourth FFR boosting level pattern is [group 1, group 2, Group 3, Group 4] = [Non-Boo Sting, non - boosting, non - it can be represented respectively boosting, the boosting. The serving cell can inform the terminal of such FFR boosting level pattern information for neighboring cells performing FFR.

  Unlike the method of notifying the terminal of the boosting and non-boosting levels for the multiple cells in which the base station performs FFR as described above, the terminal may use the FFR boosting level pattern set in advance based on the cell ID. By using, FFR can be performed efficiently without a separate instruction from the base station. That is, the terminal can efficiently perform FFR based on the cell IDs of neighboring cells that perform FFR. The terminal can efficiently perform FFR by using an FFR boosting level pattern preset by a cell function value (for example, (cell ID modulus (1 / partial frequency reuse rate)) value of an adjacent cell. In this case, if the UE acquires only the cell ID of the neighboring cell in the measurement process, the UE can perform FFR without any additional instruction from the base station. Boosting and non-boosting levels can have the same power level.

  For example, assuming an FFR system operating at a partial frequency reuse ratio of 1/3, the UE performs FFR according to a predefined FFR boosting level pattern based on the value of (cell ID modulus 3) of the neighboring cell. Can do. Referring to Table 1, when (cell ID modulus 3) = 0, FFR boosting level pattern of cell A = [boosting, non-boosting, non-boosting] can be defined as ( When cell ID modulus 3) = 1, FFR boosting level pattern of cell B = [non-boosting, boosting, non-boosting] can be defined. Similarly, when (cell ID modulus 3) = 2, the FFR boosting level pattern of cell C = [non-boosting, non-boosting, boosting] can be defined. Thus, if the terminal knows only information on the FFR boosting level pattern based on the cell ID defined in advance from the base station, the terminal can efficiently perform FFR using only the cell ID.

  As described above, each terminal performs FFR according to a pattern in which boosting and non-boosting levels corresponding to each physical frequency region are determined when a predetermined power level pattern is used based on the cell ID. be able to.

  In addition to this method, a physical frequency region having a boosting level used by each terminal can be designated as FFR group 1 and FFR can be performed using a predetermined power level pattern based on this. That is, the terminal does not perform FFR in a specific frequency region that is preliminarily classified (for example, in the case where the physical frequency region for FFR is preliminarily classified in the order of group 1, group 2, and group 3 in FIG. 5). Instead, frequency group 1 is selected based on the boosted frequency region. Also in this case, each terminal performs FFR using a power level pattern defined in advance with reference to a frequency region boosted based on the cell ID.

  Referring to FIG. 5 as an example, when the power level pattern formed based on the above-described cell ID is used, when (cell ID modulus 3) = 0, the FFR pattern of the cell A is [group 1 ( 510): boosting, group 2 (520): non-boosting, group 3 (530): non-boosting], and (cell ID modulus 3) = 1, the FFR pattern of cell B is [Group 1 (510): Non-boosting, Group 2 (520): Boosting, Group 3 (530): Non-boosting]. Similarly, when (cell ID modulus 3) = 2, the FFR pattern of cell C is [group 1 (510): non-boosting, group 2 (520): non-boosting, group 3 (530): Boosting].

  However, when a frequency region having a boosting level is designated as FFR group 1, when (cell ID modulus 3) = 0, the FFR pattern of cell A is [group 1 (510): boosting, group 2 (520 ): Non-boosting, group 3 (530): non-boosting] or [group 1 (510): boosting, group 3 (520): non-boosting, group 2 (530): non-boosting ] And (cell ID modulus 3) = 1, the FFR pattern of cell B is [group 2 (510): non-boosting, group 1 (520): boosting, group 3 (530): Non-boosting] or [Group 3 (510): Non-boosting Grayed, Group 1 (520): boosting, Group 2 (530): Non - defined boosting.

  Similarly, when (cell ID modulus 3) = 2, the FFR pattern of cell C is [group 2 (510): non-boosting, group 3 (520): non-boosting, group 1 (530): Boosting] or [group 3 (510): non-boosting, group 2 (520): non-boosting, group 1 (530): boosting].

  That is, by indexing the physical frequency region where power boosting has been performed for each cell into the same group (for example, group 1), the group indexing for the same physical frequency region can be changed for each cell. The FFR information of a new pattern configured by designating the physical frequency region where power boosting has been performed for each cell as group 1 and indexing the remaining physical frequency region into group 2 and group 3, There is a case where the terminal knows in advance even if there is no signaling as information notified to each terminal or as preset information.

  Thus, based on the fact that the frequency region where the power boosting has been performed is designated as group 1, each terminal can perform FFR using a pattern predetermined by the cell ID. This will be described in detail with reference to FIG.

  FIG. 6 is a diagram illustrating a configuration example of a soft FFR applicable when a CoMP operation is performed using the FFR scheme in a multi-cell environment.

  In FIG. 5, the FFR frequency region of each cell can be configured as a physically aligned region. That is, in FIG. 5, the same physical frequency region of each cell is represented by the same indexing (for example, 610 region: group 1, 620 region: group 2, 630 region: group 3).

  However, in FIG. 6, the physical frequency region of each cell and the corresponding indexing may be different. That is, the physical frequency region corresponding to cell A 610 corresponds to group 1 having a boosting level, the physical frequency region corresponding to cell 610 corresponds to group 3 having a non-boosting level, and corresponds to cell 610. The physical frequency regions to be performed can be shown in group 2, respectively.

  Similarly, the 620 region of cell A can be shown in group 2, the 620 region of cell B can be shown in group 1, and the 620 region of cell C can be shown in group 3. Further, the 630 region of the cell A can be shown in the group 3, the 630 region of the cell B can be shown in the group 2, and the 630 region of the cell C can be shown in the group 1.

  In this way, each cell can express and use the frequency domain with different indexing for the same physical frequency domain.

  Hereinafter, a process of acquiring a cell ID from one or more neighboring cells performing a CoMP operation in order for the terminal to perform efficient FFR based on the cell ID will be briefly described.

  FIG. 7 is a diagram illustrating an example of a downlink frame structure in a frequency division duplex (FDD) form in a 3GPP LTE system which is an example of a mobile communication system.

  Referring to FIG. 7, one downlink radio frame may be composed of 10 subframes. That is, 10 subframes can be used for downlink transmission. One subframe can be composed of two slots. One slot may include 6 or 7 OFDM (Orthogonal Frequency Division Multiplexing) symbols. Specifically, in the case of a structure using a general cyclic prefix (Normal CP), one slot may include 7 OFDM symbols, and an extended cyclic prefix (Extended CP) is used. For the structure, one slot may contain 6 OFDM symbols.

  The primary synchronization channel (P-SCH: Primary-Synchronization Channel) and the secondary synchronization channel (S-SCH: Second-Synchronization Channel) are respectively in the first slot of subframe 0 and the first slot of subframe 5 in the downlink subframe. Can be assigned. Then, the main synchronization signal can be mapped to the last OFDM symbol of slot 0 and slot 10. The sub-synchronization signal can be mapped to the symbol immediately before the symbol to which the main synchronization signal is mapped in the slots of slot 0 and slot 10.

  In an LTE system, a terminal may not know information on neighboring cells that perform CoMP operations. However, the terminal can receive cell ID set information including neighboring cell ID information from the serving base station. Therefore, the terminal can distinguish which cell is a neighboring cell through the cell ID set and the synchronization channel of each cell.

  In the LTE system, there are 504 physical cell identities (PCI: Physical Cell Identity). This physical cell ID is divided into 168 cell ID groups, and each cell ID group has three cell IDs. This can be shown as the following mathematical formula 1.

here,

Indicates the number of physical cell IDs,

Indicates the number of physical cell ID groups,

Indicates the number of cell IDs in the physical cell group ID.

  The terminal can obtain 3 pieces of cell ID information in the cell ID group through the main synchronization channel of each cell, and can obtain 168 pieces of cell ID group information through the secondary synchronization channel. The terminal can determine whether each cell is a neighboring cell based on the cell ID information via the synchronization channel of each cell. That is, the terminal can obtain sequence information used by each neighboring cell for pilot signal transmission from the synchronization channel of each neighboring cell.

  At this time, the sequence used for the main synchronization channel signal of each adjacent cell

Can be generated from the Zadoff-Chu sequence in the frequency domain according to Equation 2 below.

Here, the Zadoff-Chu root sequence index u can be given as shown in Table 1 below.

Table 3 shows each route index for a primary synchronization signal (PSS), and a sequence for the main synchronization signal can be generated according to the route index of Table 3.

  In addition, a sequence for use in a secondary synchronization signal (SSS; Second Synchronization Signal)

Is an interleaved concatenation of two 31-length binary sequences (two length-31 binary sequences). The association sequence is scrambled with a predetermined scrambling sequence by the main synchronization signal.

  A combination of two 31-length sequences can define different sub-synchronization signals of subframe 0 to subframe 5 according to the following mathematical formula 3.

here,

And index

as well as

Is a physical-hierarchical cell ID group according to the following mathematical formula 4.

It can be calculated from

When the terminal efficiently performs FFR using a preset FFR boosting level pattern based on the cell ID, the cell ID is a physical cell ID or a global cell ID, or a physical cell ID and a global ID. possible.

  Further, in a multi-cell environment, the boosting power level and the non-boosting power level for the multi-cell performing FFR can be set differently. The boosting power level for each cell and the non-boosting power level can be pre-defined as values for the quantized power level. The serving base station may inform the terminal of indexes corresponding to the quantized power levels of the boosting power level and the non-boosting power level.

The serving base station can inform the terminal of the quantized power level corresponding to each frequency resource group in a bitmap format. Also, the serving base station can inform the terminal of not only the quantized power level of each cell but also the index of the boosted frequency resource group. For example, when the power levels for frequency resources are displayed at levels P _{0 to} P ₉ and it is assumed that three cells perform FFR for three frequency resource groups, the following bit map as shown in Table 3 below. Can be shown in the form.

As described above, the terminal acquires FFR information from the serving base station and efficiently estimates the interference level of the neighboring cell, thereby improving the communication performance of the user at the cell boundary.

  The content of the FFR information that the serving base station informs the terminal has been described above. The method in which the serving base station informs the terminal of such FFR information can be divided into two cases depending on the method of configuring the CoMP set. Therefore, it is necessary to describe a method for configuring a CoMP set in a wireless communication system that performs a CoMP operation.

  In order to perform CoMP operation efficiently, it is necessary to define which neighboring cell the terminal performs CoMP. A CoMP set can be defined as a set for a neighboring cell that performs CoMP with a terminal.

  In the first case, the base station and the terminal can share information on the CoMP set in advance.

  A CoMP set shared by a base station and a terminal can be configured based on terminal measurement. Such a configuration of a CoMP set based on terminal measurement has an advantage that flexibility can be secured in setting a CoMP set for a neighboring cell that actually directly affects the terminal. The terminal can receive a list for neighboring cells given in advance from a serving base station or the like, or can form a neighboring cell list through measurements on direct neighboring cells. Thus, the terminal can perform measurement based on such a neighbor cell list. That is, the terminal can perform measurement on the interference level of the adjacent cell. The measured values for the interference level include reference symbol received power (RSRP: Reference Symbol Received Power), reference symbol received quality (RSRQ: Reference Symbol Received Quality), reference signal strength indicator (RSSI: Reference Signal Strength Streak). It may be an interference and noise ratio (CINR), a signal to interference plus noise ratio (SINR) value, a PD (propagation delay) value, or the like.

  In this manner, in the LTE system, the terminal can measure the channel quality state between the terminal itself and the cell using the reference signal received power (RSRP) corresponding to the pilot signal power. Here, the reference signal received power refers to a linear average of power distributed to resource elements to which a cell-specific reference signal is allocated within the considered measurement frequency bandwidth. The power of each resource element on the resource block can be determined from the energy received from the valid section of the symbol excluding the cyclic prefix (CP). Such reference signal received power can be applied to all terminals in the RRC_idle state and the RRC_connected state. Also, if receiver diversity is utilized by the terminal, the reported value may be equal to the linear average of each power value of all diversity branches.

  Based on such measurements on the neighboring cells of the terminal (for example, reference signal received power measurement), the terminal can report information necessary to configure the CoMP set to the serving base station. The information reported to the serving base station may include one or more values among the above-described neighboring cell measurement values and cell ID information of the corresponding neighboring cell. When the terminal forms a neighbor cell list, the cell ID information can be reported together with information on the corresponding neighbor cell measured by the terminal.

  When the serving base station provides a list of neighboring cells to the terminal in advance, the terminal transmits the measured values measured for the corresponding cell in the order of the predefined cell IDs, or in addition to the measured values, the cell ID The corresponding index can be further transmitted. Also, the index information corresponding to the cell IDs can be arranged in the order of the interference level, and the index and the measurement value corresponding to the index can be transmitted to the serving base station.

  As described above, when the serving base station and the terminal share information such as the cell ID for the CoMP set based on the terminal measurement, the serving base station may notify the terminal of the FFR information for the predefined CoMP set. it can. At this time, the serving base station can notify the terminal by arranging the FFR information in the order of predefined cell IDs or in the order of interference levels corresponding to the cell IDs, even if there is no separate cell ID information.

  As a second case, the serving base station can inform the terminal of information on the CoMP set.

  Setting a CoMP set based on terminal measurement can ensure the flexibility of setting, but the measurement overhead and feedback information transmission overhead of the terminal can be considerably increased. In such a situation, CoMP set configuration based on network parameters can be considered for proper measurement overhead and feedback information transmission overhead. That is, the serving base station can set the CoMP set even if there is no measurement of the terminal according to a specific standard. When the serving base station arbitrarily sets the CoMP set as described above, the serving base station needs to inform the terminal of multi-cell information for the CoMP set. At this time, the ID information of multiple cells belonging to such a CoMP set can be defined as a temporary base station index (temp BS index). The serving base station can set a CoMP set and inform a terminal of a temporary base station index of an adjacent cell (or base station) corresponding to the CoMP set. When the serving base station informs the terminal of such a temporary base station index, the serving base station transmits FFR information corresponding to each temporary base station index (that is, information on the temporary base station index + FFR information form) to the terminal. can do.

  The serving base station can transmit each FFR information to the terminal through higher layer signaling or L1 / L2 control signaling. The serving base station can inform the terminal of cell ID information or cell ID index of a neighboring cell corresponding to the CoMP set through higher layer signaling. The serving base station can also inform the terminal of the content of the FFR information of the corresponding neighboring cell as necessary. In addition, the serving base station can transmit this information at the time when an event-triggering is performed on a terminal to perform CoMP, or can transmit the information periodically.

In general, the base station can transmit scheduling assignment information and other control information via the PDCCH. The physical control channel can be transmitted in one aggregation or a plurality of continuous control channel elements (CCE). One CCE includes nine resource element groups. The number of resource element groups that are not allocated to PCFICH (Physical Control Indicator Indicator Channel) or PHICH (Physical Hybrid Automatic Repeat Indicator Channel) is N _REG . The CCEs available in the system are 0 to N _CCE −1 (where

Is). The PDCCH supports multiple formats as shown in Table 5 below. One PDCCH composed of n consecutive CCEs starts with a CCE that performs i mod n = 0 (where i is a CCE number). Multiple PDCCHs can be transmitted in one subframe.
Referring to Table 5, the base station can determine the PDCCH format according to how many areas the control information is transmitted to. The terminal can reduce overhead by reading control information and the like in units of CCEs.

  The serving base station can transmit cell ID information and FFR information for the CoMP set to the terminal through L1 / L2 control signaling. That is, it is possible to distinguish and design a DCI format PDCCH configured in a format according to control information to be transmitted by the serving base station. At this time, from the viewpoint of reusing the existing DCI format, some fields on an arbitrary DCI format are used, and other fields are filled with zero padding or an arbitrary value. Can also be configured.

  Hereinafter, a terminal device that estimates the channel state in the CoMP operation mode using the FFR scheme according to the present invention will be briefly described.

  FIG. 8 is a diagram showing an example of a preferred configuration of the terminal device according to the present invention.

  Referring to FIG. 8, the terminal device 800 includes a reception module 810, a processor 820, a memory unit 830, and a transmission module 840.

  The receiving module 810 includes a serving cell boosting power level value receiving module 811 that receives the serving cell boosting power level value from the serving cell, and a neighbor cell boosting power level value that receives the neighboring cell boosting power level value from the neighboring cell. A value receiving module 812. The reception module 810 can receive various signals or information from the outside such as a serving base station. For example, the receiving module 810 can receive a reference signal from a serving cell, a neighboring cell, etc. to estimate a channel state. Meanwhile, the terminal device 800 according to the present invention may know in advance power level pattern information set in advance for one or more frequency bands to which the FFR scheme is applied for each cell ID of the neighboring cell. is there.

  The processor 820 may include a cell ID acquisition module 821, a power level pattern information acquisition module 822, a channel state estimation module 823, and the like.

  The cell ID acquisition module 821 can acquire cell ID information from the serving cell and one or more neighboring cells. The power level pattern information acquisition module 822 can acquire preset power level pattern information corresponding to the acquired cell ID information. The channel estimation module 823 may estimate the serving cell channel state using the acquired power level pattern. In addition to the acquired power level pattern information, the channel estimation module 823 also uses the boosting power level value for the boosted frequency partition of the serving cell received by the reception module 811 together to serve the serving cell and / or The channel state of two or more neighboring cells can be estimated. In addition to the acquired power level pattern, the channel estimation module 823 uses the boosting power level value for the boosted frequency partition of one or more neighboring cells received by the reception module 812 together. It is also possible to estimate the channel state of one or more neighboring cells.

  The memory unit 830 can store information received by the receiving module 810, information calculated by the processor 820, and the like for a predetermined time. Such a memory unit 830 can be replaced with a buffer (not shown) or the like.

  The transmission module 840 can transmit various signals and information to the outside such as a serving base station. For example, the transmission module 840 may transmit the interference level information measured for the neighboring cell and the cell ID information of the neighboring cell to the serving base station. Also, the transmission module 840 can generate channel state information based on the channel state estimated for the neighboring cell, and can feed this back to a serving base station or the like.

  The detailed description of the preferred embodiments of the present invention disclosed above is provided to enable any person skilled in the art to implement and practice the invention. In the above, the preferred embodiments of the present invention have been described with reference to the preferred embodiments. However, those skilled in the art can modify and change the present invention in various ways without departing from the scope of the present invention. You will understand that. For example, those skilled in the art can use the configurations described in the embodiments described above in combination with each other.

  Accordingly, the present invention is not limited to the embodiments disclosed herein, but is intended to provide the widest scope consistent with the principles and novel features disclosed herein.

  A channel state estimation method in a wireless communication system using a partial frequency reuse scheme is applicable to wireless communication systems such as 3GPP LTE, LTE-A, IEEE 802.16.

Claims (12)

A method for estimating a channel state in a mobile station (MS) in a wireless communication system using a partial frequency reuse (FFR) scheme, the method comprising:
Receiving CoMP (Coordinated Multi-Point) set information from a serving cell, wherein the CoMP set is configured by the serving cell, the CoMP set including a cell performs a CoMP operation, and the cell is configured to receive the serving cell. And at least one adjacent cell;
Obtaining a serving cell identifier (ID);
If the FFR scheme is applied in the serving cell, from the acquired serving cell ID, from among three predetermined downlink power level pattern according to a predetermined rule, the four frequency partitions configured for the serving cell the method comprising: acquiring the applied downlink power level pattern, the acquired downlink power level pattern is different from the downlink power level pattern of adjacent cells of the CoMP set, and that,
When the MS performs the CoMP operation based on the information of the CoMP set, the selected PMI transmits the selected PMI to the serving cell, and the selected PMI performs the CoMP operation on the serving cell. Function as the smallest or largest interference of the adjacent cells of the CoMP set to perform
Including a method.   The method of claim 1, further comprising estimating a downlink channel condition of the serving cell based on the acquired downlink power level pattern. Obtaining an adjacent cell identifier (ID);
When FFR is applied in the adjacent cell, it is configured for the adjacent cell from among the three predetermined downlink power level patterns from the acquired adjacent cell ID according to the predetermined rule. The method of claim 1, further comprising: obtaining a downlink power level pattern applied to the four frequency partitions.   The method of claim 2, further comprising feeding back channel state information generated based on the estimated downlink channel state to the serving cell.   The method of claim 1, wherein the four frequency partitions include at least one boosted frequency partition and at least one non-boosted frequency partition.   The method of claim 5, wherein the boosted frequency partition index of the four frequency partition indexes is one.   The method of claim 1, wherein the downlink power level pattern is determined according to a serving cell ID function value.   The method of claim 7, wherein the serving cell ID function value is calculated by (serving cell ID modulus 1 / FFR rate).   The method of claim 3, further comprising estimating a downlink channel condition of the neighboring cell based on the acquired downlink power level pattern of the neighboring cell. A mobile station (MS) that estimates channel conditions in a wireless communication system using a partial frequency reuse (FFR) scheme, the MS including a receiver, a processor, and a transmitter ;
The receiver is configured to receive CoMP (Coordinated Multi-Point) set information from a serving cell, the CoMP set is configured by the serving cell, the CoMP set including a cell performs a CoMP operation, and A cell includes the serving cell and at least one adjacent cell;
The processor is
Obtaining a serving cell identifier (ID);
If the FFR scheme is applied in the serving cell, wherein the obtained information about the serving cell ID, from among three predetermined downlink power level pattern according to a predetermined rule, four frequencies that are configured for the serving cell Is configured to acquire the downlink power level pattern applied to the partition,
The acquired downlink power level pattern Unlike downlink power level pattern of adjacent cells of the CoMP set,
The transmitter is configured to transmit a selected PMI to the serving cell, and when the MS performs the CoMP operation based on the information of the CoMP set, the selected PMI is transmitted to the serving cell. MS acting as the smallest or largest interference of the adjacent cells of the CoMP set performing the CoMP operation .   The MS of claim 10, wherein the four frequency partitions include at least one boosted frequency partition and at least one non-boosted frequency partition.   The MS of claim 11, wherein the boosted frequency partition index of the four frequency partition indexes is one.