KR20140133780A - Method and apparatus for cooperative transmission of base station - Google Patents

Abstract

According to an embodiment of the present invention, a method is provided for a first base station to transmit data in cooperation with at least one neighboring base station. The first base station receives the channel status of the neighboring base station from the terminal. The first base station compares the value of the channel state with a first threshold value and a second threshold value received from the coordinator. The first base station transmits information on the neighboring base station to the coordinator when the value of the channel state is higher than the first threshold or lower than the second threshold. The first base station transmits data to the terminal based on information for cooperative transmission received from the coordinator.

Description

METHOD AND APPARATUS FOR COOPERATIVE TRANSMISSION OF BASE STATION [0002]

The present invention relates to a method for base stations to transmit data in cooperation, and to a device for cooperative transmission.

A terminal located at a cell boundary may receive interference from neighboring cells or interfere with neighboring cells, thereby degrading network performance. Therefore, in order to improve the performance of the network, it is necessary to control the interference in the cell boundary region.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cooperative transmission method and apparatus for interference control between cells.

According to an embodiment of the present invention, a method is provided for a first base station to transmit data in cooperation with at least one neighboring base station. The cooperative transmission method includes: receiving a channel state of the neighbor base station from a terminal; Comparing the value of the channel state with a first threshold value and a second threshold value received from the coordinator; Transmitting information on the neighboring base station to the coordinator when the value of the channel state is higher than the first threshold or lower than the second threshold; And transmitting data to the terminal based on information for cooperative transmission received from the coordinator.

An embodiment of the present invention relates to a method and apparatus for managing and controlling cooperative transmission through inter-cell interference control in a mobile radio access system

According to an embodiment of the present invention, inter-cell interference can be controlled in a mobile radio access system. In particular, according to an embodiment of the present invention, performance of interference control can be improved through cooperative transmission, and performance of a terminal located at a cell boundary can be improved.

1 is a diagram illustrating a concept of cooperative transmission of a base station through interference control according to an embodiment of the present invention.
2 is a diagram illustrating a group of base stations for cooperative transmission according to an embodiment of the present invention.
3 is a flowchart illustrating a cooperative transmission process according to an embodiment of the present invention.
FIG. 4 is a flowchart illustrating an operation of a terminal for BS group management according to an embodiment of the present invention.
5 is a diagram illustrating a configuration for STC encoding of a base station performing cooperative transmission according to an embodiment of the present invention.
6 is a diagram illustrating an interface for establishing cooperative transmission between a BS and a coordinator according to an embodiment of the present invention.
FIG. 7 is a diagram illustrating an embodiment of a parameter included in the C-IM-REQ message of FIG.
8 is a diagram specifically showing some parameters of Fig.
FIG. 9 is a diagram illustrating an embodiment of parameters included in the C-IM-RSP message of FIG.
10 is a diagram illustrating an interface for reporting cooperative transmission related information between a base station or a terminal and a coordinator according to an embodiment of the present invention.
11 is a diagram illustrating an embodiment of a parameter included in the C-IM-IND message of FIG.
12 is a view showing another embodiment of parameters included in the C-IM-IND message of FIG.
13 is a diagram illustrating a configuration of a base station according to an embodiment of the present invention.
14 is a diagram illustrating a configuration of a terminal according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, a terminal is referred to as a mobile terminal (MT), a mobile station (MS), an advanced mobile station (AMS), a high reliability mobile station ), A subscriber station (SS), a portable subscriber station (PSS), an access terminal (AT), a user equipment (UE) MS, AMS, HR-MS, SS, PSS, AT, UE, and the like.

Also, a base station (BS) may be an advanced base station (ABS), a high reliability base station (HR-BS), a small base station, a node B, a Node B, an eNodeB, an access point (AP), a radio access station (RAS), a base transceiver station (BTS), a mobile multihop relay (MMR) BS, ABS, HR-BS, small base station, Node B, eNodeB, AP (High Speed Relay Station), and the like may be referred to as a high reliability relay station , RAS, BTS, MMR-BS, RS, HR-RS, and the like.

The interference control according to the embodiment of the present invention can be performed using a resource management method for interference control and a cooperative transmission (CT) method using interference control. Specifically, a cooperative transmission method through interference control is a method in which a base station transmits data to a mobile station in cooperation with a neighboring base station, thereby improving the performance of the mobile station or the mobile station located at the cell boundary. The cooperative transmission method is performed through cooperation between the base stations. In particular, in a multi-layer network in which various types of cells formed through a small base station or a macro base station and a small base station are overlapped, an efficient method of base station cooperation and a management method for cooperative transmission for interference control are needed.

An embodiment of the present invention relates to a method for managing or controlling cooperation between base stations for inter-cell cooperative transmission, a resource management method through management or control, and a method for predicting or measuring inter-cell interference for interference control and cooperative transmission .

Meanwhile, a mobile radio access system according to an embodiment of the present invention includes a base station, a terminal, and a coordinator for interference control. Specifically, the base station and the terminal exchange data through wireless communication. The coordinator for interference control can directly manage or control the terminal, or indirectly manage or control the terminal through the base station. On the other hand, the coordinator may be an independent device separate from the base station. Alternatively, the coordinator may be included in the base station. Hereinafter, for convenience of description, an embodiment of the present invention will be described by taking, as an example, a case where the coordinator is an independent apparatus that is separate from the base station. Hereinafter, for convenience of description, embodiments of the present invention will be described by taking a downlink service between a base station and a terminal as an example. However, this is merely an example, and the embodiment of the present invention can be applied to the uplink service in the same or similar manner as that in the downlink service.

1 is a diagram illustrating a concept of cooperative transmission of a base station through interference control according to an embodiment of the present invention.

The base stations 201, 301, and 302 capable of performing cooperative transmission can simultaneously improve the quality of services by providing services to the terminals. Here, the base stations 201, 301, and 302 capable of cooperative transmission can be managed in one group (or set). Specifically, the base stations 201, 301, and 302 cooperate with each other (T1). The UE 101 measures the channel state and reports the measurement result to the serving BS 201 (T2). The serving base station 201 and the neighboring base stations 301 and 302 simultaneously perform cooperative transmission to transmit data to the mobile station (T3). On the other hand, in the cooperative transmission, only one of the base stations 201, 301, and 302 may transmit data to the mobile station, and the remaining base stations may not be configured to transmit data to the mobile station during cooperative transmission. As a result, inter-cell interference can be further reduced.

Meanwhile, the basic requirements necessary for the base station to perform cooperative transmission (T3) are as follows.

The base stations 201, 301, and 302 performing the cooperative transmission time synchronize based on a common time source. In addition, the synchronization of each data frame transmitted by the base stations 201, 301, and 302 performing the cooperative transmission is matched, and each data frame is transmitted to the terminal within a minimum allowable error (e.g., an OFDMA prefix) do. In addition, the base stations 201, 301, and 302 that perform cooperative transmission use the same frequency. When establishing a connection between the terminal 101 and the base station 201, a connection identifier (CID) allocated to the terminal 101 and managed by the base station 201 is transmitted to base stations 201, 301, and 302 share each other and use the same connection identifier. In addition, the base stations 201, 301, and 302 that perform cooperative transmission transmit data in the form of a MAC (Media Access Control) or a PHY (Physical Data Unit) PDU to the UE 101. Also, in the process of capability negotiation performed at the time of initial connection between the base station 201 and the terminal 101, the terminal 101 can transmit to the base station 201 whether the cooperative transmission can be supported. In this way, the base stations 201, 301, and 302 can perform cooperative transmission more efficiently. However, the process of transmitting the cooperative transmission support availability to the terminal 101 is optional. On the other hand, even when the negotiation of the support capability of the cooperative transmission is not performed or the terminal does not have the capability of supporting cooperative transmission, cooperative transmission between the base stations 201, 301 and 302 is possible, The cooperative transmission is performed in a state in which it is not noticed that the service is being provided through the communication network.

2 is a diagram illustrating a group of base stations for cooperative transmission according to an embodiment of the present invention.

As illustrated in FIG. 2, the base station can be divided into base stations (BS1 to BS7, BS9, BS12 to 14) capable of cooperative transmission and base stations (BS8, BS10, BS11) Specifically, the Cooperative Transmission Candidate Set (hereinafter referred to as 'CT CANDIDATE SET') includes base stations (BS1 to BS7, BS9 and BS12 to 14) capable of cooperative transmission and is managed by a coordinator. The cooperative transmission candidate set represents a base station group capable of performing cooperative transmission according to the channel status and the like. The cooperative transmission set (hereinafter, referred to as 'CT SET') includes base station groups (BS1 to BS4) that actually perform cooperative transmission by the coordinator among the base stations (BS1 to BS7, BS9 and BS12 to 14) . That is, a plurality of base stations (BS1 to BS4) belonging to the cooperative transmission set can simultaneously transmit data to the terminal 102. [

On the other hand, the transmission antennas of each of the base stations BS1 to BS4 included in the cooperative transmission set belong to one transmission antenna pool. The coordinator selects some or all of the antennas belonging to the transmission antenna pool, and groups the selected antennas. Grouped antennas are used for cooperative transmission. On the other hand, the terminal 102 regards that the data is logically transmitted at one transmission time, and can receive the data.

3 is a flowchart illustrating a cooperative transmission process according to an embodiment of the present invention. Specifically, FIG. 3 illustrates a management interface and procedure for IM. The operation procedure of the cooperative transmission will be described with reference to FIG. 2 and FIG. For convenience of explanation, a case where the base station BS1 is a serving base station and a network control management system (NCMS) is a coordinator for controlling interference management (IM) will be described as an example.

The terminal 102 measures the state of a channel for wireless communication (e.g., Signal to Interference plus Noise Ratio (SINR), Carrier to Interference Noise Ratio (CINR), and the like) and reports the measurement result to the serving base station BS1 (S110). Here, the channel state may include interference information by neighboring base stations (e.g., BS2 to BS4).

The serving BS BS1 reporting the channel status reports the channel status to the coordinator for interference control (S120). Specifically, the serving BS BS1 reports to the coordinator every time the channel status is less than or equal to the threshold value, periodically reports the channel status to the coordinator every time the channel status is reported from the terminal, or receives a report request from the coordinator Can be reported. Meanwhile, the serving base station BS1 notifies the coordinator only of the channel status of the base station that can report only the channel status of the base station capable of cooperative transmission or perform performance enhancement (enhancement of network performance, terminal performance, etc.) Can be reported. Alternatively, since the coordinator selects a base station for cooperative transmission and selects an antenna, the serving base station BS1 may report only the channel status result to the coordinator. In this case, the coordinator can select some or all of the base stations corresponding to the reported channel conditions. Meanwhile, the coordinator can select a cooperative transmission mode (method).

The coordinator that has reported the channel status result from at least one base station BS1 determines whether the cooperative transmission is performed according to the channel status of each base station at step S130. Specifically, the coordinator can receive and report the channel status not only from the serving base station BS1 but also from other base stations (e.g., BS2 to BS4) managed by the coordinator. If it is determined that a cooperative transmission (e.g., a start of a cooperative transmission, a change in cooperative transmission, etc.) is needed, the coordinator, in accordance with the cooperative transmission mode (method) And requests the neighboring base stations BS2 to BS4 for cooperative transmission (S141 to S143). Specifically, the coordinator can request cooperative transmission to some or all of the base stations included in the reported channel status result. The base stations BS1 to BS4 transmit a message to the coordinator in response to the cooperative transmission request (S141 to S143). On the other hand, the coordinator may change the existing cooperative transmission for cooperative transmission and may not cooperate when cooperative transmission is determined to be no longer needed. In addition, the coordinator may allow the serving base station to initiate cooperative transmission without considering cooperative transmission.

Before the BSs BS1 to BS4 provide a service to the MS 102, the coordinator determines whether only some of the BSs BS1 to BS4 among the BSs are set as resources (by resource management for interference control) Resources), and the remaining base stations can be configured not to use the resources.

The base stations BS1 to BS4 that have requested the cooperative transmission perform cooperative transmission (S151 to S153). Specifically, the base stations BS1 to BS4 can simultaneously provide services to the terminal 102 using the set resources. That is, the base stations BS1 to BS4 can transmit the same data to the terminal 102 at the same time.

The UE 102 may measure the channel status of the received resource and report it to the serving BS 1 (S160).

The serving BS BS1 may report the reported channel status to the coordinator (S170). Thereafter, the coordinator can reset or terminate the cooperative transmission method through the above-described processes (S130, S141 to S143).

Meanwhile, when the UE 102 reports the channel status to the serving BS1 (S110), the UE 102 transmits the channel status to the serving BS 1 Can be reported. The first reporting condition is a first case in which a channel status report is requested from the base station BS1, a second case in which a timer corresponding to a transmission period expires when the terminal 102 is set to periodically transmit the channel status, And a fourth case in which the value of the channel state is increased or decreased by a predetermined value or more than the previously measured value, and the fourth case in which the value of the channel state is not less than the upper limit threshold value or less than the lower limit threshold value. have. This first reporting condition may be informed by the base station BS1 to the terminal 102, or may be applied in a predefined manner. For example, if the serving base station BS1 provides the terminal 102 with a first reporting condition that includes the first and second cases of the first through fourth cases, If the second case is satisfied, the serving BS can report the channel status.

On the other hand, in a process of S120 in which the BS1 reporting the channel status reports the channel status to the coordinator, the BS1 reports the channel status to the coordinator when the second report condition is satisfied have. The second report condition is that when a channel status report is received from the terminal 102, a channel status report is requested from the coordinator, and a base station BS1 is set to periodically transmit the channel status, When the value of the channel state for reporting is increased or decreased by a predetermined value or more than the previously measured value and when the value of the channel state is equal to or higher than the upper threshold value or lower than the lower threshold value have.

FIG. 4 is a flowchart illustrating an operation of a terminal for BS group management according to an embodiment of the present invention. A CT SET management method for cooperative transmission will be described with reference to FIG. 2 and FIG.

The coordinator provides an upper limit channel state threshold (CT_Add_Threshold) and a lower limit channel state threshold (CT_Delete_Threshold) to the base station (BS1) for management of the CT SET for cooperative transmission. The upper limit channel state threshold value (CT_Add_Threshold) is a threshold for including the cooperative transmittable base station in the CT CANDIDATE SET, and the lower limit channel state threshold value (CT_Delete_Threshold) is a threshold value for excluding from the CT CANDIDATE SET. The base station BS1 may also provide the lower terminal 102 with a threshold value CT_Add_Threshold, CT_Delete_Threshold, based on the provided thresholds CT_Add_Threshold and CT_Delete_Threshold.

The terminal 102 measures a channel state of a neighboring base station (S210).

When the terminal 102 is provided with the threshold value CT_Add_Threshold and CT_Delete_Threshold at step S220, the terminal 102 compares the measured channel state value with the threshold value CT_Add_Threshold and CT_Delete_Threshold at steps S230 and S240. Specifically, the terminal 102 determines whether there is a channel state that is equal to or higher than the upper limit channel state threshold value CT_Add_Threshold in the measured channel state (S230).

The terminal 102 transmits information of a neighboring base station corresponding to a channel state having an upper limit channel state threshold (CT_Add_Threshold) or higher to the serving base station BS1 (S280). Here, the neighbor BS information may include channel state information and may be used for CT SET management. Specifically, the terminal 102 may transmit a message to the serving base station BS1 requesting to add a neighboring base station corresponding to a channel state equal to or higher than the upper limit channel state threshold value CT_Add_Threshold to the CT CANDIDATE SET.

Meanwhile, the terminal 102 determines whether there is a channel state that is equal to or lower than the lower limit channel state threshold CT_Delete_Threshold in the measured channel state (S240).

The terminal 102 transmits information of a neighboring base station corresponding to a channel state having a lower limit channel state threshold (CT_Delete_Threshold) or less to the serving base station BS1 (S250). Specifically, the UE 102 may transmit to the serving BS BS1 a message requesting removal of a neighboring BS corresponding to a channel state lower than the lower limit channel state threshold CT_Delete_Threshold, from the CT CANDIDATE SET.

The UE 102 may periodically transmit the measurement result of the channel state to the serving BS BS1 or may transmit the measurement result of the channel state to the serving BS BS1 in a case where the value of the channel state exceeds the upper limit channel state threshold value CT_Add_Threshold, (CT_Delete_Threshold) or lower) is satisfied. Specifically, when the terminal 102 is set to transmit the channel state periodically, the terminal 102 reports the channel state of the neighboring base station to the serving base station BS1 when the transmission period timer expires, even if the terminal 102 does not have the thresholds CT_Add_Threshold and CT_Delete_Threshold. (S260, S270). In this case, the serving base station BS1 or the coordinator can manage the CT SET based on the channel state transmitted in the process of step S270.

The operation of the base station BS1 for CT SET management is as follows.

The base station BS1 compares the channel status reported from the terminal 102 with the threshold values CT_Add_Threshold and CT_Delete_Threshold provided from the coordinator. The base station BS1 determines a neighbor base station to be included in the CT CANDIDATE SET or a neighbor base station to be excluded from the CT CANDIDATE SET according to the comparison result. The base station BS1 may report to the coordinator a list of base stations (e.g., a list of base stations to be included in the CT CANDIDATE SET or a list of base stations to be excluded from the CT CANDIDATE SET) and the channel status of base stations belonging to the base station list.

The coordinator finally manages (e.g., creates, updates, or releases) the CT SET based on the information reported from the base station BS1. The CT SET information changed by the management of the coordinator is provided to the base stations (e.g., BS2 and BS4) included in the changed CT SET. The BSs BS2 and BS4 provided with the changed CT SET information can use the corresponding information in the cooperative transmission. Specifically, the base stations BS2 and BS4, which have received the changed CT SET information, can perform cooperative transmission using the changed information from the time when the changed information is applied.

Meanwhile, for efficient CT SET management, the base station BS1 can provide a list of base stations that are currently capable of cooperative transmission to the terminal 102, and allow the terminal 102 to measure the channel status of base stations belonging to the base station list . Accordingly, the terminal 102 can be guided to inhibit the channel measurement of the unnecessary neighbor base stations, and can measure the channel of the base station belonging to the CT CANDIDATE SET and the CT SET in order to update the CT SET. In this case, the coordinator can assign a temporary identifier (temporary member identifier) to the base station belonging to the CT CANDIDATE SET, thereby reducing the overhead between the base station and the terminal. Here, the temporary identifier may be expressed in the form of an index in the CT CANDIDATE SET, or may be expressed using a part of the base station identifier (e.g., a part of the LSB (Least Significant Bits)). In the case where the temporary identifiers of the respective base stations are represented in the form of an index, the temporary identifiers can be changed during the cooperative transmission, and can notify the terminal 102 of the change. Meanwhile, the connection identifier assigned to the terminal 102 at the time of establishing a connection between the base station BS1 and the terminal 102 may be changed. In addition, when configuring the CT CANDIDATE SET (e.g., when changing a member belonging to the CT CANDIDATE SET, etc.), the base station identifier and the temporary identifier corresponding to the change member can be changed.

On the other hand, the physical channel measurement method includes a sounding-based channel estimation method and a midamble channel measurement method. First, a sounding-based channel estimation method will be described. The base station BS1 that provides the service through the cooperative transmission may request the terminal 102 supporting uplink sounding to transmit a sounding signal. The terminal 102 can exchange sounding support information with the base station BS1 during the capacity negotiation process during the initial access of the terminal 102 to the base station BS1. Meanwhile, in order to perform sounding-based channel estimation, the BS 1 allocates resources (hereinafter, referred to as 'sounding resources') for transmission of sounding signals to the AT 102. In this case, neighboring base stations (e.g., BS2 to BS4) that perform cooperative transmission with the base station BS1 do not use the sounding resources allocated by the base station BS1 for purposes other than sounding-based channel estimation. The base station BS1 may estimate a channel together with neighboring base stations in a sounding-based downlink channel estimation. The base station BS1 estimates a downlink channel based on the measured channel state (channel information). On the other hand, the base station BS1 may report the measured channel status or received channel information (e.g., size, etc.) to the coordinator to perform a persistent cooperative transmission. The coordinator can appropriately control cooperative transmission for downlink data transmission based on information reported from at least one base station BS1. Meanwhile, the base station BS1 may perform a coordinator role for cooperative transmission, and may control neighboring base stations (e.g., BS2 to BS4) that perform cooperative transmission in this case.

The channel measurement method through the midamble will be described. The base station BS1 that performs cooperative transmission transmits a signal (e.g., a preamble, a midamble, and a pilot) for channel measurement in a specific area. The terminal 102 receiving the service through the cooperative transmission measures the channel through the corresponding signal (e.g., preamble, midamble, and pilot). The terminal 102 reports the measured channel state to the base station BS1, and the reported base station BS1 reports the received channel state to the coordinator. The subsequent process is carried out according to the above-described method.

5 is a diagram illustrating a configuration for STC (Space Time Code) encoding of a base station performing cooperative transmission according to an embodiment of the present invention.

The base station BS1 performs sub-channel modulation through the sub-channel modulation processing unit 410, performs an IFFT input packet through an IFFT (Inverse Fast Fourier Transform) input packing processing unit 420, And performs IFFT processing through the IFFT processing unit 440. [ The base station BS1 performs filtering on the output signal of the IFFT processing unit 440 through the filter 450 and performs analog-to-digital conversion on the output signal of the filter 450 through a digital to analog converter (DAC) . The base station BS1 transmits an output signal of the DAC 460 through a radio frequency (RF) transmitter 470. [

Specifically, the base station BS1 performs STC encoding so that the antennas allocated for cooperative transmission (antennas used for cooperative transmission) transmit data to the terminal (e.g., 102). On the other hand, the base station BS1 may use a non-assigned antenna (not used for cooperative transmission) to serve a terminal other than the terminal 102, or an antenna not allocated for cooperative transmission may transmit data . Unassigned antennas for cooperative transmission may be grouped or selected so that the base station BS1 may be used to perform cooperative transmissions for other terminals than the terminal 102. [

The terminal 102 receiving the data transmitted through the cooperative transmission decodes the received signal. Specifically, the terminal 102 does not recognize that the data is transmitted through the cooperative transmission, and can consider that one base station is serving through multiple antennas and can decode it. That is, each of the antennas of the base stations (e.g., BS1 to BS4) participating in the cooperative transmission is regarded as each of the antennas (hereinafter referred to as 'second antenna') used for data transmission in one base station. Each first antenna is logically mapped to each second antenna and transmits a reference signal (e.g., a preamble, a midamble, or a pilot) transmitted by each second antenna. This antenna setting is performed by the coordinator, and the already set value is held until there is a new setting by the coordinator. Specifically, the coordinator may include the time at which the antenna setting is applied or the time at which the antenna setting expires. Accordingly, the coordinator can efficiently perform cooperative transmission between the base stations. On the other hand, when the expiration time is included in the setting, the base station BS1 may expect a new setting before the timer corresponding to the expiration time expires.

Meanwhile, a method of managing an anchor base station for cooperative transmission is as follows. For convenience of explanation, it will be described with reference to Fig.

At the beginning of the cooperative transmission, the serving base station BS1 is generally regarded as an anchor base station, and data exchange is performed between the base station (e.g., BS1 to BS4) and the terminal 102 through cooperative transmission. The anchor base station plays a role of performing necessary control so that the lower terminal 102 can receive the service through the cooperative transmission, and the terminal 102 monitors the anchor base station and expects the control setting. During the cooperative transmission, the anchor base station can be changed according to the channel states of the respective base stations (BS1 to BS4) performing the cooperative transmission. The base station (e.g., BS1) can notify the terminal 102 after changing the anchor base station. Alternatively, the terminal 102 may request the base station BS1 to set one base station among the base stations belonging to the CT SET, or a third base station not belonging to the CT SET as an anchor base station. The base station BS1 may respond to the request of the terminal 102 by accepting or changing an anchor base station change. On the other hand, the selection of an anchor base station can be performed by the coordinator, and in this case, the base station BS1 can transmit a request from the terminal 102 to the coordinator. On the other hand, when changing the anchor base station, the previous anchor base station transfers the MAC context of the terminal 102 to the new anchor base station, and changes (reallocation, additional allocation, deletion, etc.) ), And it is possible to update the temporary identifier (temporary member identifier).

On the other hand, a method of applying interference control is as follows. For convenience of explanation, it will be described with reference to Fig. The base stations (for example, BS1 to BS4) receiving the configuration information for the cooperative transmission from the coordinator can apply the interference control based on the received information. Specifically, the time point at which the interference control is applied may be a period immediately after receiving the related information, a predetermined time, or after a predetermined time elapses from the time when the related information is received. The coordinator can control the base station setting by including the interference control application time point information in the configuration information for cooperative transmission.

The format of the threshold value (CT_Add_Threshold, CT_Delete_Threshold) transmitted from the base station (e.g., BS1) to the terminal (e.g., 102) is shown in Table 1 below.

Name Type (1 byte) Length Value
(variable length) PHY scope CT_Add_Threshold xxx One - A threshold used by the terminal to add the neighboring base station to the CT CANDIDATE SET.
- If the CINR of the neighboring base station is higher than CT_Add_Threshold, the terminal transmits an IM_CT-REQ message requesting to add the neighboring base station to the CT CANDIDATE SET
- Used for cooperative transmission
Used in decibels (unit of decibels)
- If the base station does not support cooperative transmission, CT_Add_Threshold is not set OFDMA CT_Delete_Threshold xxx + 1 One - The threshold used by the terminal, used to exclude the base station from the CT CANDIDATE SET.
- If the CINR of the base station is lower than CT_Delete_Threshold, the terminal transmits an IM_CT-REQ message requesting to exclude the base station from the CT CANDIDATE SET
- Used for cooperative transmission
Used in decibels (unit of decibels)
- If the base station does not support cooperative transmission, CT_Add_Threshold is not set OFDMA

On the other hand, a format of a message (e.g., an anchor BS update message, a CT SET update message, a CID update message, a temporary member identifier (Temp BS ID) update message, etc.) transmitted from a base station (e.g. BS1) Is shown in Table 2 below.

Syntax Size (bit) Notes IM_CT-RSP_Message_Format () { - -   Management Message Type = xx + 1 8 -   Action Type 8 - Used to indicate the purpose of the message.
- Bit 0: Anchor BS update
- Bit 1: CT CANDIDATE SET update
- Bit 2: CID update during anchor BS update or CT CANDIDATESET update
- Bit 3: Temp BS ID update
- Bit 4-7: Reserved   if (Action Type [Bit 0] == 1) { - -     TEMP_BSID_Anchor 4 Temp BS ID for the new anchor BS.   } - -   if (Action Type [Bit 1] == 1) { - -     N_New_Temp_BSID 4 Number of new BSs to add in the CT CANDIDATE SET.     Reserved 4 Shall be set to zero.     for (i = 0; i <N_New_Temp_BSID; i ++) { - -       Neighbor BS ID 48 -       Temp BS ID 4 Member ID of the CT CANDIDATE SET.       Reserved 4 Shall be set to zero.     } - -     N_Temp_BSID 4 Number of BSs which is the member of new CT CANDIDATE SET     Reserved 4 Shall be set to zero.     for (i = 0; i <N_Temp_BSID; i ++) { - -       Temp BS ID 4 Member ID of the CT CANDIDATE SET       Reserved 4 Shall be set to zero     }   } - -   if (Action Type [Bit 2] == 1) { - -     N_CID_Add 4 Number of CIDs to add     N_CID_Update 4 Number of CIDs to update     N_CID_Delete 4 Number of CIDs to delete     Reserved 4 Shall be set to zero     for (i = 0; i <N_CID_Add; i ++) { - -       New_CID_Add 16 New CID to use in the Multi-BS CT     }     for (i = 0; i <N_CID_Update; i ++) { - -       Current_CID_Update 16 Current CID to delete in the Multi-BS CT       New_CID_Update 16 New CID to add in the Multi-BS CT     }     for (i = 0; i <N_CID_Delete; i ++) { - -       Current_CID_Delete 16 Current CID to delete from the Multi-BS CT     }   } - -   if (Action Type [Bit 3] == 1) { - -     N_Temp_BSID_Update 4 Number of Temp BS ID to update     for (i = 0; i <N_Temp_BSID_Update; i ++) { - -       Current_Temp_BSID_Update 16 Current Temp BS ID to delete in the Multi-BS CT       New_Temp_BSID_Update 16 New Temp BS ID to add in the Multi-BS CT     }   } }

Meanwhile, a message requesting the terminal (e.g., 102) to transmit a message to the base station (e.g., BS1) (e.g., a message requesting the neighbor base station to add to the CT CANDIDATE SET, Anchor base station update message, etc.) are shown in Table 3 below.

Syntax Size
(bit) Notes IM_CT-REQ_Message_Format () { - -  Management Message Type = xx 8 -  Action Type 8 Used to indicate the purpose of the message
- Bit 0: a message requesting that the neighboring base station (s) be added to the CT CANDIDATE SET
- Bit 1: Message requesting to exclude neighboring base station (s) from CT CANDIDATE SET
- Bit 2: Message requesting to update the anchor base station
- Bit 3-7: Reserved  Report metric 8 - Bitmap indicating presence of certain thresholds on which the corresponding triggers are based:
Bit 0: BS CINR mean
Bit 1: BS RSSI mean
Bit 2: Relative delay
Bits 3-7: Reserved; shall be set to zero.  if (Action Type [Bit 0] == 1) { - -   N_Neighbor_BS_Index 8 Number of neighbor BSs are included in MOB_NBR-ADV message   if (N_Neighbor_BS_Index! = 0) { - -    Configuration change code for MOB_NBR-ADV 8 Configuration Change Count value of MOB_NBR_ADV message   } - -   for (i = 0; i <N_Neighbor_BS_Index; i ++) { - -    Neighbor_BS_Index 8 BS index does not correspond to position in BS in MOB_NBR-ADV message    if (Report metric [Bit 0] == 1) - -     BS CINR mean 8 -    if (Report metric [Bit 1] == 1) - -     BS RSSI mean 8 -    if (Report metric [Bit 2] == 1) - -     Relative delay 8 -    } - -  } - -   N_Neighbor_BS_Full 8 Number of neighbor BSs that are using full 48bits BSID   for (i = 0; i <N_Neighbor_BS_Full; i ++) { - -    Neighbor BS ID 48 -    if (Report metric [Bit 0] == 1) - -     BS CINR mean 8 -    if (Report metric [Bit 1] == 1) - -     BS RSSI mean 8 -    if (Report metric [Bit 2] == 1) - -     Relative delay 8 -   } - -  } - -   N_Temp_BSID 4 Number of BSs in the Multi-BS CT candidate set   Reserved 4 Shall be set to zero   for (i = 0; i <N_Temp_BSID; i ++) { - -    Temp BS ID 4 Member ID of the Multi-BS CT candidate set    Reserved 4 Shall be set to zero    if (Report metric [Bit 0] == 1) - -     BS CINR mean 8 -    if (Report metric [Bit 1] == 1) - -     BS RSSI mean 8 -    if (Report metric [Bit 2] == 1) - -     Relative delay 8 -   } - -  } - -  if (Action Type [Bit 1] == 1) { - -   N_Temp_BSID 4 Number of BSs in the CT CANDIDATE SET   Reserved 4 Shall be set to zero.   for (i = 0; i <N_Temp_BSID; i ++) { - -    Temp BS ID 4 Member ID of the CT CANDIDATE SET    Reserved 4 Shall be set to zero    if (Report metric [Bit 0] == 1) - -     BS CINR mean 8 -    if (Report metric [Bit 1] == 1) - -     BS RSSI mean 8 -    if (Report metric [Bit 2] == 1) - -     Relative delay 8 -   } - -  } - -  if (Action Type [Bit 2] == 1) { - -   Temp_BSID 4 Member ID of the CT CANDIDATE SET   Reserved 4 Shall be set to zero  } - - }

6 to 12, the interface between the base station, the terminal and the coordinator for cooperative transmission will be described. The NCMS in Figs. 6 to 12 may be a coordinator.

6 is a diagram illustrating an interface for cooperative transmission setup between a BS (e.g., BS1) and a coordinator according to an embodiment of the present invention.

The coordinator transmits a request message (for example, a C-IM-REQ message) for cooperative transmission to a base station BS1 through a control plane-service access point (C-SAP) (E.g., a C-IM-RSP message) for cooperative transmission to the coordinator. The C-IM-REQ message will be described in detail with reference to FIGS. 7 and 8, and the C-IM-RSP message will be described in detail with reference to FIG.

FIG. 7 is a diagram illustrating an embodiment of a parameter included in the C-IM-REQ message of FIG. 8 is a diagram specifically showing some parameters in Fig. 7 (loop for (i = 0, i <N_PERMUTATION_ZONES; i ++)).

The C-IM-REQ message is a message in which the coordinator requests the base station BS1 for configuration for cooperative transmission. The parameters that may be included in the C-IM-REQ message are as illustrated in FIG. Specifically, as shown in Table 4 below, the Request Type parameter indicates the request type, the bit 0 of the Request Type indicates the type requesting the cooperative transmission, and the bit 1 of the Request Type indicates the type requesting the status report . When the Request Type parameter is bit 0 (i.e., 'Set the Multi-BS CT'), the parameters illustrated in Table 5 below are validated.

parameter Remarks Request Type - Type of request; bitmap:
a) Bit 0: Set the Multi-BS CT
b) Bit 1: Report status

parameter Remarks N_PERMUTATION_ZONES - Number of radio frame subsections for which resource partition will be indicated.
- A value of 1 indicates that the entire DL and UL radio subframe is considered to be a single permutation zone. Permutation scheme - Denotes the permutation scheme used in the current permutation zone.
- The following types are possible:
a) DL PUSC permutation
b) DL FUSC permutation
c) DL Optional FUSC permutation
d) DL AMC
e) DL TUSC1
f) DL TUSC2
g) UL PUSC
h) UL AMC Permutation Zone Subchannel Bitmap - Indicates the subchannels available for transmission in the current permutation zone Use All SC - When set, this field indicates transmission on all available subchannels.
- For FUSC permutation, transmission is always on all subchannels. DL_PermBase - DL Permutation base for the specified DL zone.
- DL_PermBase field shall be set to the 5 LSBs of IDcell indicated by the frame preamble. PRBS_ID - Values: 0..2 AMC type - Indicates the AMC type in case permutation type = 0b11, otherwise shall be set to 0.
- AMC type (NxM = N bins by M symbols):
a) 1x6
b) 2x3
c) 3x2
- Note that only 2x3 band AMC subchannel type (AMC Type = 0b01) is supported by MS OFDMA Symbol Offset - Denotes the start of the current permutation zone in number of OFDMA symbols (counting from the frame preamble and starting from 0) Number of OFDMA Symbols - Denotes the number of OFDMA symbols used in the current permutation zone. Subchannel offset - Denotes the start of the current zone in number of OFDMA subchannels Number of Subchannels - Denotes the number of OFDMA subchannels used in the currnet permutation zone. Tx Power - Denotes the maximum transmit power used in the current permutation zone (in dBm). STC - Denotes the STC in the current permutation zone:
a) No STC
b) STC using 2 antennas
c) STC using 3 antennas
d) STC using 4 antennas
e) FHDC using 2 antennas Midamble presence - Indicates midamble presence in the first symbol of the current permutation zone with the corresponding antenna configuratio. Midamble boosting - Indicates whether the midamble is boosting. Dedicated Pilots - Indicates whether the pilot symbols are broadcast or dedicated:
a) broadcast
b) dedicate N_CT - Indicates the number of Multi-BS CT supported in the current permutation. Multi-BS CT_ID - Indicates identifier of the Multi-BS CT. Anchor Temp BSID - Indicates the Temp BSID (member ID) of the anchor BS in the Multi-BS CT group (identified by Multi-BS CT ID). Temp BSID - Indicates the Temp BSID (member ID) of the BS in the Multi-BS CT group (identified by Multi-BS CT ID). N_BS_SETS - Number of neighbor BSs in the current Multi-BS CT group (identified by Multi-BS CT ID). Neighbor BSID - ID of the neighbor BS Neighbor Temp BSID - Temp BSID of the neighbor BS in the Multi-BS CT group (identified by Multi-BS CT ID). Matrix indicator - Indicates the STC matrix to be used in the Multi-BS CT:
a) Matrixe
b) Matrix B
c) Matric C Antenna index of BS - Indicates the antenna index of the BS. Antenna index for Multi-BS CT - Indicates the antenna index to be used in the Multi-BS CT. CT Add Threshold - Indicates the threshold values to add the neighbor BS to the multi-BS CT CANDIDATE SET. CT Delete Threshold - Indicates the threshold values to delete the neighbor BS from the multi-BS CT CANDIDATE SET. Action Time - Denotes the time to start this action.

On the other hand, when the Request Type parameter is set to bit 1 (i.e., 'Report status'), the parameters illustrated in Table 6 below are validated.

parameter Remarks Report type - Indicates the type to report the status:
a) report the link level quality for a specific MS Report Characteristics - Indicates whether the report will be sent periodically, or event driven.
a) Bit 0: Periodically as defined by report period.
b) Bit 1: regularly whenever resource is changed as defined by RT.
c) Bit 2: Change of IM RM configuration (set the partition). This report will be given whenever any of the parameters (Request type [bit 0] is set to 'Set the Multi-BS CT') at the BS have changed.
d) Bit 3: Report shall be given per permutation zone. Report Period P
- The Time P is used by the BS as a reporting period for producing the information requested by the NCMS. Report Threshold RT - The threshold value will be used by the BS to send report as soon as possible. MS MAC Address - 48-bit unique identifier of the MS.
- Only valid when the report type is for 'report the link level quality for a specific MS'

FIG. 9 is a diagram illustrating an embodiment of parameters included in the C-IM-RSP message of FIG. The C-IM-RSP message is a response message to the cooperative transmission setup request of the coordinator. The parameters that may be included in the C-IM-RSP message are as illustrated in FIG. Specifically, as shown in Table 7 below, the Response Type parameter in FIG. 9 indicates the type of the report profile.

parameter Remarks Response Type - Type of report profiles:
a) Multi-BS CT configuration complete
b) PHY Report

When the Response Type parameter is set to 'Multi-BS CT configuration complete', the parameters illustrated in Table 8 below are validated.

parameter Remarks Update Type - Type of update; bitmap:
a) Bit 0: Anchor BS update
b) Bit 1: Multi-BS CT CANDIDATE SET update
c) Bit 2: CID update during anchor BS update or Multi-BS CT CANDIDATE SET update
d) Bit 3: Temp BS ID update Multi-BS CT ID - Indicates identifier of the Multi-BS CT. Anchor Temp BSID - Temp BS ID of the anchor BS, which is the member ID of the Multi-BS CT SET. N_Temp_ID - The counter of the Temp BSID Temp BSID - Member identifier of the Multi-BS CT CANDIDATE SET. N_CID - The counter of the CID CID - Connection identifier

On the other hand, when the Response Type parameter is set to 'PHY report', the parameters illustrated in Table 9 below are validated.

parameter Remarks MS MAC Address - 48-bit unique identifier of the MS Temp BSID for PHY report - Member identifier of the Multi-BS CT Downlink Physical Service Level - Channel rate available for the MS calculated as a multiple of 1/32 of nominal bandwidth in the correspondent direction assuming 1 bit / Hz.
- For example, if DL channel bandwidth is 10 MHz, value PSL = 4 means 4 x 1/32 x 10 Mbps = 1.25 Mbps.
- 1 PSL 96 (number of subchannels in different OFDMA modes is multiple of 16 or 32, highest modulation (QAM64) provides 3 bits / Hz) Downlink RSSI mean Downlink RSSI standard deviation Downlink CINR mean Downlink CINR standard deviation Uplink Physical Service Level - Channel rate available for the MS calculated as a multiple of 1/32 of nominal bandwidth in the correspondent direction assuming 1 bit / Hz. (see definition of Downlink Physical Service Level) Uplink RSSI mean Uplink RSSI standard deviation Uplink CINR mean Uplink CINR standard deviation

10 is a diagram illustrating an interface for reporting cooperative transmission related information between a base station or a terminal and a coordinator according to an embodiment of the present invention.

Specifically, when a base station (e.g., BS1) receives a message, it may send a message (e.g., a C-IM-IND message) for cooperative transmission to the coordinator via C-SAP. In addition, when the UE (e.g., 102) receives a message, it may transmit a message (e.g., a C-IM-IND message) for cooperative transmission to the coordinator via C-SAP. The C-IM-IND message will be described in detail with reference to FIG. 11 and FIG.

11 is a diagram illustrating an embodiment of a parameter included in the C-IM-IND message of FIG. Specifically, the C-IM-IND message illustrated in FIG. 11 is a message transmitted when the base station BS1 reports information related to cooperative transmission to the coordinator. As described above in FIG. 3, the cooperative transmission related report can be performed by the base station BS1 when the second reporting condition is satisfied. The parameters that can be included in the C-IM-IND message are as illustrated in FIG. Specifically, as shown in Table 10 below, the Indication Type parameter in FIG. 11 indicates the type of the reporting profile.

parameter Remarks Indication Type - Type of report profiles:
a) PHY Report

On the other hand, when the Indication Type parameter is set to 'PHY report', the parameters illustrated in Table 11 below are validated.

parameter Remarks MS MAC Address - 48-bit unique identifier of the MS. Temp BSID for PHY report - Member identifier of the Multi-BS CT for PHY report Downlink Physical Service Level - Channel rate available for the MS calculated as a multiple of 1/32 of nominal bandwidth in the correspondent direction assuming 1 bit / Hz.
- For example, if DL channel bandwidth is 10 MHz, value PSL = 4 means 4 x 1/32 x 10 Mbps = 1.25 Mbps.
- 1 PSL 96 (number of subchannels in different OFDMA modes is multiple of 16 or 32, highest modulation (QAM64) provides 3 bits / Hz) Downlink RSSI mean Downlink RSSI standard deviation Downlink CINR mean Downlink CINR standard deviation Uplink Physical Service Level - Channel rate available for the MS calculated as a multiple of 1/32 of nominal bandwidth in the correspondent direction assuming 1 bit / Hz. (see definition of Downlink Physical Service Level) Uplink RSSI mean Uplink RSSI standard deviation Uplink CINR mean Uplink CINR standard deviation

12 is a view showing another embodiment of parameters included in the C-IM-IND message of FIG. Specifically, the C-IM-IND message illustrated in FIG. 12 indicates that the terminal (for example, 102) having received the update request for the cooperative transmission related information from the base station (e.g., BS1) informs the coordinator that the update has been completed The message being transmitted. The parameters that can be included in the C-IM-IND message are as illustrated in FIG. Specifically, the parameters illustrated in FIG. 12 can be defined as shown in Table 12 below.

parameter Remarks Operator ID - Identifier of the network provider Indication Type - Type of indication; bitmap:
a) Bit 0: Anchor BS update
b) Bit 1: Multi-BS CT CANDIDATE SET update
c) Bit 2: CID update during anchor BS update or Multi-BS CT CANDIDATE SET update
d) Bit 3: Temp BS ID update Anchor Temp BSID - Temp BS ID of the anchor BS, which is the member ID of the Multi-BS CT SET N_Temp_ID - The counter of the Temp BSID Temp BSID - Member identifier of the Multi-BS CT CANDIDATE SET N_CID - The counter of the CID CID - Connection identifier

13 is a diagram showing a configuration of a base station 201 according to an embodiment of the present invention.

Base station 201 may include memory 210, processor 220, and RF converter 230.

The processor 220 may be configured to implement the procedures, methods, and functions described in Figures 1-12.

The memory 210 is coupled to the processor 220 and may store various information related to the operation of the processor 220.

The RF converter 230 may be coupled to the processor 220 and may transmit or receive a radio signal. Meanwhile, the base station 201 may have a single antenna or multiple antennas.

14 is a diagram showing a configuration of a terminal 100 according to an embodiment of the present invention.

The terminal 100 may include a memory 110, a processor 120, and an RF converter 130. The terminals 101 and 102 may be configured to be the same as or similar to the terminal 100.

The processor 120 may be configured to implement the procedures, methods, and functions described in Figures 1-12.

The memory 110 is coupled to the processor 120 and may store various information related to the operation of the processor 120.

The RF converter 130 is coupled to the processor 120 and can transmit or receive radio signals. Meanwhile, the terminal 100 may have a single antenna or multiple antennas.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (1)

A method for a first base station to transmit data in cooperation with at least one neighboring base station,
Receiving a channel state of the neighboring base station from a terminal;
Comparing the value of the channel state with a first threshold value and a second threshold value received from the coordinator;
Transmitting information on the neighboring base station to the coordinator when the value of the channel state is higher than the first threshold or lower than the second threshold; And
Transmitting data to the terminal based on information for cooperative transmission received from the coordinator
/ RTI &gt;

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