KR20120016534A - Method and apparatus for data transmission in cellular wireless communication system - Google Patents

Abstract

The present invention relates to a method and apparatus for increasing reliability of control information when cross-carrier scheduling in a wireless communication system constituting a broadband through carrier aggregation. Specifically, the present invention provides a method of informing a control format indicator (CFI) to a terminal operating a plurality of component carriers.

Description

METHOD AND APPARATUS FOR TRNSMITTING DATA IN CELLULAR COMMUNICATION SYSTEM}

The present invention relates to a cellular wireless communication system, and more particularly, to a method and apparatus for notifying a terminal of a data transmission start time in a system supporting carrier aggregation.

In recent mobile communication systems, orthogonal frequency division multiple access (OFDMA), or a similar method, is useful for high-speed data transmission in a wireless channel. Division Multiple Access (hereinafter referred to as SC-FDMA) is being actively researched. Here, the multiple access method has orthogonality so that time-frequency resources for carrying data or control information for each user do not overlap each other. As such, time-frequency resources are allocated and operated to have orthogonality with each other, thereby distinguishing data or control information of each user.

Currently, the 3rd Generation Partnership Project (3GPP), an asynchronous cellular mobile communication standard organization, has completed the standardization of Long Term Evolution (LTE), the next generation mobile communication system, and studies LTE-Advanced (LTE-A) system, which is an evolution of LTE. In the process. The LTE and LTE-A systems operate based on the orthogonal frequency division multiple access scheme.

Orthogonal frequency division multiple access classifies each user's data or control information by assigning and operating them so that time-frequency resources to carry data or control information for each user do not overlap, that is, orthogonality is established. . In the case of the control channel, additional code resources are allocated to distinguish the control information of each user.

 1 is a diagram illustrating a time-frequency domain transmission structure of data or a control channel in downlink of an LTE-A system according to the prior art.

Referring to FIG. 1, the vertical axis represents a time domain and the horizontal axis represents a frequency domain. The minimum transmission unit in the time domain is an OFDM symbol, N _symb OFDM symbols 101 are collected to form one slot, and two slots are together to form one subframe 103. The minimum transmission unit in the frequency domain is the subcarrier 105, and the entire system transmission band 109 consists of a total of NBW subcarriers.

The basic unit of resource in the time-frequency domain may be defined as an OFDM symbol index and a subcarrier index as a resource element (107). A resource block (RB) is defined as N _symb consecutive OFDM symbols in the time domain and NRB consecutive subcarriers in the frequency domain. One RB is composed of N _symb x N _RB REs. In general, the minimum transmission unit of data is RB units. In the current LTE system, N _symb = 7, N _RB = 12, and the value of N _BW is proportional to the system transmission band.

The control channel is transmitted within the first 3 OFDM symbols in the subframe. That is, according to the amount of control information to be transmitted in the current subframe, the number of OFDM symbols to which the control channel is transmitted varies from 1, 2, or 3 from the start of the subframe. The control information includes downlink control information (DCI) indicating uplink or downlink scheduling information, and control information transmission interval information (CFI) indicating whether the control information transmission interval is one of the 1, 2, or 3 OFDM symbols. Format Indicator).

CFI is transmitted through a Physical Control Format Indicator Channel (PCFICH), which is a physical control channel for CFI transmission. After the CFI is channel coded, it is mapped to four Resource Element Groups (REGs) 111, 113, 115, and 117 evenly spaced across the system transmission band in the frequency domain, and mapped to the first OFDM symbol in the subframe in the time domain. do. And REG consists of four consecutive REs.

DCI is transmitted through a physical downlink control channel (PDCCH) which is a downlink physical control channel. In general, DCI is channel-coded independently for each UE, and then configured with each independent PDCCH and transmitted. The PDCCH is transmitted during the OFDM symbol period indicated by the CFI transmitted through the PCFICH. The frequency domain mapping position of the PDCCH is determined by the ID of each UE, and is spread over the entire system transmission band.

The downlink data is transmitted through a physical downlink shared channel (PDSCH), which is a physical channel for downlink data transmission. The PDSCH is transmitted after the control channel transmission interval indicated by the CFI, and control information such as specific mapping positions and modulation schemes in the frequency domain is informed by the PDCCH transmitting the DCI.

2 is a diagram illustrating a process of receiving downlink data by a terminal in an LTE or LTE-A system according to the prior art.

Referring to FIG. 2, the terminal performs initial access from a synchronization channel (SCH) transmitted by a base station in step 201. The terminal synchronizes time synchronization with the cell through initial access and obtains a cell ID. Next, the UE receives a physical broadcast channel (PBCH) using the cell ID obtained in step 203 and obtains system information such as downlink system bandwidth from the PBCH. The terminal detects the frequency domain position of the PCFICH from the cell ID and downlink system transmission band information obtained in step 205 and receives the PCFICH. The terminal obtains the CFI information indicating the time domain transmission section of the control channel from the PCFICH. For reference, the time domain position of the PCFICH is fixed to the first OFDM symbol in the subframe.

The UE recognizes the time domain transmission section of the PDCCH from the CFI information obtained in step 207. The terminal receives the PDCCH by identifying the frequency domain position of the PDCCH from the terminal ID. Thereafter, control information such as resource allocation information and modulation scheme required for receiving downlink data is obtained from the received PDCCH. Next, the terminal receives the PDSCH from the control information obtained in step 209.

One of the important things for providing high-speed wireless data service in cellular wireless communication system is support of scalable bandwidth. For example, the Long Term Evolution (LTE) system may have various bandwidths such as 20/15/10/5/3 / 1.4 MHz. Service providers can select one of the various bandwidths to provide a service. In addition, there may be various types of terminals, such as those capable of supporting a maximum bandwidth of 20 MHz to only a minimum of 1.4 MHz bandwidth. In addition, the LTE-A system, which aims to provide a service of an IMT-Advanced requirement level, may provide broadband services up to 100 MHz bandwidth through LTE aggregation of carriers.

LTE-A system requires broadband than LTE system for high-speed data transmission. At the same time, backward compabitility for LTE terminals is also important, so that LTE terminals should also be able to access the LTE-A system and receive services. To this end, the LTE-A system divides the entire system band into subbands or component carriers (CCs) of a bandwidth that can be transmitted or received by the LTE terminal, and combines predetermined component carriers. The LTE-A system generates and transmits data for each component carrier. Accordingly, the transmission / reception process of the existing LTE system is utilized for each component carrier and can support high-speed data transmission of the LTE-A system.

FIG. 3 is a diagram illustrating three configured carriers in each of uplink and downlink in the LTE-A system according to the prior art.

Referring to FIG. 3, a component carrier which is a reference among carrier carrier components combined is called a primary carrier or primary component carrier. The component carrier other than the primary carrier is called a non-primary carrier or a non-primary component carrier. The base station (eNode B, or base station (BS)) informs the user equipment (UE) which base station (carrier) to configure which carrier to operate as a base station signaling. In general, the base station configures how many component carriers to combine through higher signaling.

In the case of downlink, initial system information or higher signaling is transmitted through a component carrier set to a primary carrier. The primary carrier may be a reference component carrier for controlling terminal mobility. In addition, in the case of uplink, a component carrier on which a UE performs random access after initial access to a system may be an uplink primary carrier.

 3 shows an example in which downlink and uplink are combined and operated by three component carriers, and downlink component carrier # 0 and uplink component carrier # 0 are set to primary carriers of downlink and uplink, respectively. 3 illustrates an example of symmetrical carrier combining in which the number of component carriers in the uplink and the number of component carriers in the downlink are the same, asymmetrical carrier combinations in which the number of component carriers in the uplink / downlink are different from each other is also possible.

In the LTE-A system, data is generated and transmitted for each component carrier. The scheduling information on the data transmitted for each component carrier informs the terminal as Downlink Control Information (DCI) transmitted through the PDCCH. DCI is defined in various formats, whether it is scheduling information for uplink data or scheduling information for downlink data, whether it is a compact DCI, whether spatial multiplexing using multiple antennas is applied, or whether it is DCI for power control. It is operated by applying a predetermined DCI format depending on whether or not.

FIG. 4 is a diagram illustrating each component carrier in which a base station schedules downlink data to a terminal in the LTE-A system according to the prior art.

Referring to FIG. 4, a CFI 415 indicating a control channel transmission interval of a downlink component carrier # 0 (CC # 0, 401) is a PCFICH 411 transmitted from CC # 0 401. The terminal is notified through. 4 illustrates a case where CFI of CC # 0 is 2.

The scheduling information 407 for scheduling the PDSCH 423 of CC # 0 transmitted to a predetermined UE is transmitted through the PDCCH 427 after channel coding and interleaving. The PDCCH 427 is mapped during the first 2 OFDM symbols in a subframe in the time domain as notified by the CFI 415, and in the frequency domain is mapped so as not to overlap with other terminals according to the terminal ID.

The PDSCH 423 is transmitted from the control channel transmission interval notified by the CFI 415 until the end of the corresponding subframe. Control information such as frequency domain resource information and modulation scheme of the PDSCH 423 of CC # 0 is scheduled 419 to the PDCCH 427 of CC # 0.

Similarly, the CFI 417 indicating the control channel transmission interval of the downlink component carrier # 1 (CC # 1, 403) is transmitted to the UE through the PCFICH 413 transmitted from the CC # 1 403. You are notified. 4 illustrates that CFI of CC # 1 is three.

The scheduling information 409 for scheduling the PDSCH 425 of CC # 1 transmitted to the predetermined UE is transmitted through the PDCCH 429 after channel coding and interleaving. The PDCCH 429 is mapped during the first 3 OFDM symbols in a subframe in the time domain as notified by the CFI 417, and is mapped so as not to overlap with other terminals according to the terminal ID in the frequency domain.

The PDSCH 425 is transmitted from the control channel transmission interval notified by the CFI 417 until the end of the corresponding subframe. Control information such as frequency domain resource information and modulation scheme of the PDSCH 425 of the CC # 1 is informed by the PDCCH 429 of the CC # 1 as indicated by reference numeral 421.

In the carrier-coupled LTE-A system, cross carrier scheduling in which the PDCCH scheduling PDSCH is transmitted on a component carrier different from the component carrier on which the PDSCH is transmitted is considered. Cross carrier scheduling is a scheduling method for transmitting a PDCCH through a component carrier with low interference as a countermeasure when the reception reliability of a control channel such as a PDCCH is poor due to severe interference in a specific component carrier. In the case of PDSCH, even if transmitted through a component carrier with high interference, it can be compensated by frequency selective scheduling that maps to a frequency region where interference is relatively low among the entire system transmission bands, and by retransmission method of HARQ (Hybrid Automatic Repeat reQuest).

Therefore, it is necessary to define a series of procedures for notifying CFI and transmitting / receiving PDCCH and PDSCH in the cross carrier scheduling method as described above. An object of the present invention for solving the above problems is to provide a method and apparatus for notifying CFI and transmitting / receiving PDCCH and PDSCH in a wireless communication system constituting a broadband through carrier aggregation.

In order to solve the above problems, the data transmission method of the present invention comprises the step of configuring the control information transmission interval information of the first component carriers by radio resource control signaling and transmitting through the downlink data channel of the second component carriers, Transmitting a downlink control channel for scheduling a downlink shared channel of a first component carrier through the second component carrier, and a downlink data channel of the first component carrier according to scheduling information of the downlink control channel Comprising a step of transmitting through the first component carrier.

In addition, the data receiving method of the present invention to obtain the control information transmission interval information of the first component carrier in the downlink data channel received through the second component carrier to solve the above problems, and the control information transmission interval Receiving a downlink control channel for scheduling a downlink data channel of the first component carrier according to the information through the second component carrier; and scheduling the first component carrier according to the scheduling information of the received downlink control channel. The method includes receiving the downlink data channel.

In order to solve the above problems, the data transmission apparatus of the present invention determines whether to combine carriers with respect to a terminal to be scheduled and whether to transmit scheduling information through a component carrier of the first and second component carriers when performing carrier combining. The carrier combining controller, a scheduler for inputting control information transmission interval information for a component carrier to transmit scheduling information determined through the carrier combining controller, and a control information transmission interval information input from the scheduler according to a control format indication channel transmission format. And formatting the control format indication channel block and the control information transmission section information. The OMDDM generator may generate the multiplexed control information transmission section information as a signal to be transmitted to the terminal.

Next, in order to solve the above problems, the data receiving apparatus of the present invention performs channel decoding of a control format indication channel to obtain a control information transmission interval information, and a downlink through the control information transmission interval information. A downlink control channel block for acquiring scheduling information, a downlink data channel block for acquiring data from a downlink data channel received through the downlink scheduling information, and a downlink control channel and downlink data for each component carrier And an FM signal receiver that receives the channel.

The present invention provides a method and apparatus for notifying CFI with high reliability and transmitting / receiving PDCCH and PDSCH even in a poor channel environment in a wireless communication system constituting a broadband through carrier aggregation.

1 is a view showing a time-frequency domain transmission structure of a data or control channel in downlink of the LTE-A system according to the prior art.
2 is a diagram illustrating a process of receiving downlink data by a terminal in an LTE or LTE-A system according to the prior art.
FIG. 3 is a view illustrating three component carriers combined for uplink and downlink in the LTE-A system according to the prior art. FIG.
4 is a diagram illustrating each component carrier in which a base station schedules downlink data to a terminal in the LTE-A system according to the prior art;
5 is a diagram illustrating a cross carrier scheduling operation according to the first embodiment of the present invention.
6 is a diagram illustrating a base station procedure according to the first embodiment of the present invention.
7 is a diagram illustrating a terminal procedure according to the first embodiment of the present invention.
8 illustrates cross carrier scheduling in a heterogeneous network according to a second embodiment of the present invention.
9 is a diagram illustrating a base station apparatus according to an embodiment of the present invention.
10 is a diagram illustrating a terminal device according to an exemplary embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with the accompanying drawings. In addition, in describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intentions or customs of the user, the operator, and the like. Therefore, the definition should be based on the contents throughout this specification.

In addition, in describing the embodiments of the present invention, an advanced E-UTRA (or LTE-A) system supporting carrier aggregation will be the main target, but the main points of the present invention are similar. Other communication systems having a technical background and a channel form may be applied with a slight modification without departing from the scope of the present invention, which may be determined by those skilled in the art. For example, the subject matter of the present invention can be applied to multicarrier HSPA supporting carrier combining.

An important aspect of the present invention is to provide a control information transmission interval information to a terminal when cross carrier scheduling is performed for a terminal activated to set up and operate multiple carriers in a wireless communication system constituting a broadband through carrier aggregation. The present invention provides a method and apparatus for reporting a Control Format Indicator (CFI) and transmitting a downlink control channel (PDCCH) and a downlink data channel (PDSCH). The cross carrier scheduling is a scheduling method of a case in which a component carrier on which a PDCCH is transmitted and a component carrier on which a PDSCH is transmitted are different from each other. For example, cross carrier scheduling is a supplementary measure when reception reliability of a control channel such as a PDCCH becomes poor due to severe interference in the first component carrier (hereinafter referred to as 'component carrier A' for convenience of description). The reception reliability of the PDCCH may be improved by transmitting the PDCCH through a second component carrier having low interference (hereinafter, referred to as 'component carrier B' for convenience of description).

On the other hand, PDSCH is complemented by frequency selective scheduling that maps to a relatively low frequency region of the entire system transmission band even though it is transmitted through highly constituent carrier A and retransmission of HARQ (Hybrid Automatic Repeat reQuest). This is possible. However, in the case of PDCCH, HARQ is not applied, and the mapping position in the time-frequency domain is fixed by the terminal ID and the CFI value. Therefore, if cross carrier scheduling is not applied, the reception performance of the PDCCH may be severe in the constituent carrier B having a poor channel environment such as interference.

For cross carrier scheduling, the base station additionally adds a carrier indicator (CI) to the DCI indicating the DCI indicating scheduling information for the PDSCH to schedule the PDSCH of the PDSCH to generate a PDCCH and transmit it to the UE. do. For example, CI = '00' represents scheduling information for DL CC # 0, and CI = '01' represents scheduling information for DL CC # 1.

The physical control indicator channel (PCFICH) that transmits CFI information is also not subjected to HARQ as in the case of PDCCH, the position in the time domain is fixed to the first OFDM symbol in the subframe, and the position in the frequency domain It is fixed by the cell ID value. When the transmission is performed on the component carrier A, which has a poor channel environment due to interference or the like, the reception performance of the PCFICH may be drastically deteriorated. Therefore, in this case, the CFI information of 'Component Carrier A' provided by the PCFICH is configured from 'Component Carrier B', which has a relatively good channel environment, to 'Radio Resource Control Signaling (RRC) Signaling'. Informs the UE through PDSCH.

The CFI value through RRC signaling includes CFI = {1, 2, 3} through the existing PCFICH, and CFI = 4 is also defined. Accordingly, the control channel transmission interval in 'component carrier A' is relatively broadly controlled without additional signaling overhead increase. That is, the CFI value of 'component carrier A' is set to one of {1, 2, 3, 4} through 2-bit RRC signaling. The relationship between 2-bit RRC signaling and CFI may be defined as in the example of [Table 1].

RRC signaling value CFI meaning ‘00’ One The control channel is transmitted during the first 1 OFDM symbol in a subframe or the PDSCH is transmitted from the second OFDM symbol in a subframe. ‘01’ 2 The control channel is transmitted during the first 2 OFDM symbols in the subframe or the PDSCH is transmitted from the third OFDM symbol in the subframe. ‘10’ 3 The control channel is transmitted during the first 3 OFDM symbols in a subframe or the PDSCH is transmitted from the fourth OFDM symbol in a subframe. ‘11’ 4 The control channel is transmitted during the first 4 OFDM symbols in a subframe or the PDSCH is transmitted from the fifth OFDM symbol in a subframe.

In addition, a carrier indicator (CI) or a CC identifier having an equivalent role is added to the RRC signaling to distinguish which component CFI is indicated.

The present invention can be applied without limitation to the number of carriers constituting a broadband through carrier combination. Hereinafter, the specific method proposed by the present invention will be described through the following examples.

<First Embodiment>

In the first embodiment, in the LTE-A system in which two component carriers CC # 0 and CC # 1 are combined, when the base station transmits downlink data to the terminal through cross carrier scheduling, The example which applied operation | movement is shown.

5 is a diagram illustrating a cross carrier scheduling operation according to a first embodiment of the present invention.

5 is a downlink component carrier # 0 (CC # 0, 501) according to the present invention, assuming that the channel environment is a poor 'component carrier A', the downlink component carrier # 1 ( The downlink component carrier # 1; CC # 1, 503 is assumed to be 'component carrier B' having a good channel environment. Accordingly, the base station configures the scheduling information 507 for scheduling the PDSCH 527 of CC # 0 as the PDCCH 519 and transmits it through CC # 1 having a good channel environment. The base station configures the scheduling information 509 for scheduling the PDSCH 529 of the CC # 1 as the PDCCH 521 and transmits the information through the CC # 1 having a good channel environment. Since CC # 1 has a good channel environment, the CFI 513 of CC # 1 is normally notified to the terminal through the PCFICH 511 of CC # 1. In FIG. 5, the CFI of CC # 1 is 3, and in the case of CC # 0, since the channel situation is not good, the CFI 515 of CC # 0 is configured with RRC signaling and notified to the UE through PDSCH of CC # 1. In FIG. 5, when the CFI of CC # 0 is 4, the PDCCH 519 and the PDCCH 521 transmitted in CC # 1 are mapped during the first 3 OFDM symbols in a subframe in the time domain as notified by the CFI 513. The PDCCH 519 and the PDCCH 521 are mapped so as not to overlap each other in the frequency domain. Accordingly, each of the PDCCH 519 and the PDCCH 521 includes a CI, and the UE can know which component carrier PDSCH is scheduled through the CIs included in the PDCCH 519 and the PDCCH 521.

Since the CFI 513 of CC # 1 is CFI = 3, the PDSCH 529 of CC # 1 is transmitted from the fourth OFDM symbol in the subframe until the end of the corresponding subframe. Since the CFI 515 of CC # 0 is CFI = 4, the PDSCH 527 of CC # 0 is transmitted from the fifth OFDM symbol in the subframe until the end of the corresponding subframe.

6 is a diagram illustrating a base station procedure according to a first embodiment of the present invention. In more detail, FIG. 6 illustrates a base station procedure for transmitting a PDSCH on the 'component carrier A' during cross carrier scheduling according to the example of FIG. 5.

Referring to FIG. 6, in step 601, the base station configures CFI of CC # 0 through RRC (Radio Resource Control) signaling and transmits the CFI to CC through PDSCH of CC # 1. Next, the base station transmits a PDCCH for cross carrier scheduling the PDSCH of CC # 0 to the UE through CC # 1 in step 603. In step 605, the base station configures a PDSCH according to the scheduling information of the PDCCH in step 603 and transmits the PDSCH to the terminal through CC # 0.

7 is a diagram illustrating a terminal procedure according to a first embodiment of the present invention. In more detail, FIG. 7 illustrates a UE procedure for receiving a PDSCH from the 'component carrier A' during cross carrier scheduling according to the example of FIG. 5.

Referring to FIG. 7, the UE acquires CFI information of CC # 1 through PCFICH of CC # 1 in step 701. The UE receives the PDCCH for scheduling the PDSCH in CC # 1 and the corresponding PDSCH based on the CFI information obtained in step 701 in step 703. The UE acquires CFI information of CC # 0 included in the RRC signaling form in the PDSCH. Thereafter, in step 705, the UE receives the PDCCH for cross carrier scheduling the PDSCH of CC # 0 through CC # 1. In step 707, the UE receives the PDSCH in CC # 0 according to the scheduling information of the PDCCH in step 705.

The first embodiment may be variously modified. As an example, CFI = {0, 1, 2, 3} including CFI = 0 in addition to the existing RRC signaled CFI value {1, 2, 3} It can be configured as. CFI = 0 means that the control channel transmission interval of the CC that is cross carrier scheduling is '0', so that control channels such as PDCCH and PCFICH are not transmitted in the corresponding CC. Therefore, the cross carrier scheduling CC can reduce the overhead caused by the control channel to increase the data transmission efficiency. When the CFI of the CC that is cross carrier scheduling is signaled as '0', the PDSCH of the CC is mapped and transmitted from the first OFDM symbol in the subframe. In such a modified example, the relationship between RRC signaling and CFI may be defined as in the example of [Table 2].

RRC signaling value CFI meaning ‘00’ One The control channel is transmitted during the first 1 OFDM symbol in a subframe or the PDSCH is transmitted from the second OFDM symbol in a subframe. ‘01’ 2 The control channel is transmitted during the first 2 OFDM symbols in the subframe or the PDSCH is transmitted from the third OFDM symbol in the subframe. ‘10’ 3 The control channel is transmitted during the first 3 OFDM symbols in a subframe or the PDSCH is transmitted from the fourth OFDM symbol in a subframe. ‘11’ 0 Control channel is not transmitted in subframe or PDSCH is transmitted from the first OFDM symbol in subframe.

As another modified example of the first embodiment, it is defined that the UE interprets the RRC signaled CFI differently according to the system bandwidth of the component carrier constituting carrier combining. When the system bandwidth of the component carrier is small, a small bandwidth of the frequency domain may cause a problem of insufficient capacity of the transmittable control channel. In this case, it is possible to alleviate the problem of insufficient capacity of the control channel in the corresponding component carrier by increasing the transmission interval of the control channel in the time domain from the existing maximum 3 OFDM symbols to 4 OFDM symbols. In other words, if the RFI signaled CFI is defined as CFI = {1, 2, 3}, the base station selects one of the predefined CFI values and notifies the terminal. Then, if the system bandwidth of the CC to which the RRC signaled CFI is to be applied is equal to or less than a predetermined reference value, for example, 1.4 MHz, the terminal interprets the control channel transmission interval of the CC as 'RRC signaled CFI' + 1. On the other hand, if the system bandwidth of the CC to which the RRC signaled CFI is applied is greater than a predetermined reference value, for example, exceeding 1.4 MHz, the terminal interprets the control channel transmission interval of the CC as the 'RRC signaled CFI'. Table 3 shows how to interpret the CFI differently according to the system bandwidth of the component carrier.

Alternatively, the set of RRC signaled CFI values is defined as {1, 2, 3, 4}, and if the system bandwidth of the component carrier to be cross carrier scheduled is large, the base station selects one of {1, 2, 3}. To transmit to the terminal. On the other hand, if the system bandwidth of the component carrier is small, the base station selects one of {2, 3, 4} and transmits it to the terminal. At this time, the terminal operates by interpreting the signaled CFI value.

Second Embodiment

The second embodiment shows a specific embodiment to which the operation of the present invention is applied when supporting carrier coupling in a heterogeneous network including a macro cell and a pico / femto cell. In general, a macro cell has a large cell coverage due to a large base station transmission power, and a pico / femto cell has a small cell coverage due to a small base station transmission power.

8 is a diagram illustrating a cross carrier scheduling operation in a heterogeneous network according to a second embodiment of the present invention. In more detail, FIG. 8 illustrates an example in which a macro cell supports carrier combining consisting of CC # 0 and CC # 1, and the pico / femto cell supports carrier combining consisting of CC # 0 and CC # 1. Indicates.

When the base station transmission timing in the macro cell and the base station transmission timing in the pico / femto cell are not synchronized with each other, the macro cell starts transmitting at time t2 (827), and the pico / femto cell transmits at time t1 (825). Is started, assuming that there is a time difference by Δ = t 2 -t 1. In order to avoid interference between the macro cell and the pico / femto cell, in particular, between the macro cell control channel and the pico / femto cell control channel in the control channel transmission interval, the PDCCH of the macro cell is transmitted in CC # 1807. The PDCCH of the pico / femto cell is exemplified by the CC # 0 (809).

The control channel transmission section of CC # 1 807 of the macro cell is transmitted to the UE as CFI information of the PCFICH transmitted to CC # 1. In FIG. 8, it is assumed that the control channel transmission interval of the macro cell CC # 1 is assumed to be CFI = 3 (815). The control channel transmission interval of the macro cell CC # 0 805 informs the UE through RRC signaling included in the PDSCH transmitted in the macro cell CC # 1.

In FIG. 8, it is assumed that the control channel transmission interval of the macro cell CC # 0 is assumed to be CFI = 2 (813). The macro cell base station transmits the PDCCH 817 and the PDCCH 819 through the macro cell CC # 1 to schedule the UE # 1 belonging to the macro cell. Here, the PDCCH 819 informs the UE of scheduling information for the PDSCH 823 of the macro cell CC # 1. The PDCCH 817 informs the UE of scheduling information about the PDSCH 821 of the macro cell CC # 0 by a cross carrier scheduling method. Then, the UE # 1 receives the PDCCH 817 and the PDCCH 819 and recognizes that data is scheduled to the CC in each CC. The terminal receives the PDSCH 823 from the scheduling information of the PDCCH 819 and the CFI = 3 of the macro cell CC # 1 in the macro cell CC # 1. The UE receives the PDSCH 821 from the scheduling information of the PDCCH 817 and the CFI of the macro cell CC # 0 in the macro cell CC # 0.

The CC # 0 809 control channel transmission section of the pico / femto cell informs the UE as CFI information 835 of the PCFICH transmitted to CC # 0. In FIG. 8, the control channel transmission interval of the pico / femto cell CC # 0 is CFI = 2. The control channel transmission interval of pico / femto CC # 1 811 informs the UE through RRC signaling included in PDSCH transmitted in pico / femto cell CC # 0. As described above, the macro cell and the pico / femto cell differ in transmission time by Δ. The control channel transmission interval of the macro cell CC # 1 807 is for CFI = 3 OFDM symbols from the time t2 827 to the time t5 833. Accordingly, the control channel transmission section of the pico / femto cell CC # 1 811 is set so as not to overlap the control channel transmission section of the macro cell CC # 1 807 where signals are transmitted with relatively high transmission power. Accordingly, performance degradation due to interference between the macro cell CC # 1 807 and the pico / femto cell CC # 1 811 is prevented. That is, when the control channel transmission interval of the pico / femto cell CC # 1 811 is set to CFI = 4 (837), the control channel transmission interval of the pico / femto cell CC # 1 811 is t1 (825). Up to time t5 (833) becomes 4 OFDM symbols. Accordingly, interference between the macro cell CC # 1 807 and the pico / femto cell CC # 1 811 may be avoided. Thus, the pico / femto cell base station sets the control channel transmission interval of the pico / femto cell CC # 1 811 to satisfy the following conditions.

'Control channel transmission section of pico / femto cell CC # 1 ≥ Control channel transmission section of macro cell CC # 1 + Δ'

In the control channel transmission section of the macro cell CC # 0 and the control channel transmission section of the pico / femto cell CC # 1, only a minimum control channel may be transmitted or no control channel may be transmitted at all for avoiding interference.

The Pico / femto cell base station transmits the PDCCH 839 and the PDCCH 841 through the pico / femto cell CC # 0 in order to schedule the terminal # 2 belonging to the pico / femto cell. The PDCCH 839 informs scheduling information about the PDSCH 843 of the pico / femto cell CC # 0. The PDCCH 841 informs the UE of the scheduling information for the PDSCH 845 of the pico / femto cell CC # 1 by a cross carrier scheduling method. UE # 2 receives the PDCCH 839 and the PDCCH 841 and recognizes that data is scheduled to the CC in each CC. The terminal # 2 receives the PDSCH 843 from the scheduling information of the PDCCH 839 in the pico / femto cell CC # 0 and the CFI = 2 of the pico / femto cell CC # 0. UE # 2 receives PDSCH 845 from scheduling information of PDCCH 841 in pico / femto cell CC # 1 and CFI = 4 of pico / femto cell CC # 1.

9 illustrates a base station apparatus according to an embodiment of the present invention.

Referring to FIG. 9, a carrier aggregation controller 902 may determine whether carrier aggregation is performed with respect to a UE to be scheduled by referring to the amount of data to be transmitted to the UE, the amount of resources available in the system, the channel state of each component carrier, and the like. In case of carrier combining, the scheduling information is transmitted to the scheduler 904 to determine which component carrier to transmit. The scheduler 904 controls the PCFICH block 906, the PDCCH block 912, and the PDSCH block 920.

The PCFICH block 906 formats the CFI value input from the scheduler 904 in accordance with the PCFICH transmission format (PCFICH formatting) 908, and then adds an error correction capability in the channel coding unit 910 to provide a multiplexer (PCFICH). multiplexing (928). In this case, the PCFICH may or may not be transmitted according to the component carrier.

The downlink control channel block (PDCCH block) 912 receives scheduling information from the scheduler 904, formats the DCC according to the DCI format (DCI formatting) 914, and then performs error correction capability in the channel coding unit 916. Add. Thereafter, the PDCCH block 912 applies rate matching (918) to the multiplexer 928 after rate matching (918) according to the amount of resources to be mapped. At this time, when cross carrier scheduling, the component carrier on which the PDCCH is transmitted and the component carrier on which the PDSCH is transmitted are different.

The downlink data channel block (PDSCH block) 920 extracts data to be transmitted to the terminal from the data buffer 922 according to the scheduler 904 decision. The PDSCH block 920 adds error correction capability in the channel coding unit 924 to the extracted data, and then rate matches 926 according to the amount of resources to be mapped. The PDSCH block 920 applies rate-matched data to the multiplexer 928. In this case, when CFI information of a specific component carrier is transmitted through RRC signaling, the RRC signaling is transmitted through the PDSCH.

The multiplexed signal in the multiplexer 928 undergoes a scrambling 930 and a modulation 932 and then is mapped to a time-frequency resource to be actually transmitted through a resource mapping unit 934. Finally, the signal passing through the OFDM signal generator 936 is transmitted to the terminal.

10 illustrates a terminal device according to an embodiment of the present invention.

Referring to FIG. 10, the terminal extracts a PCFICH / PDCCH / PDSCH, etc. through a resource demapping unit 1004 for a signal received from a base station through an OFDM signal receiver 1002. The terminal performs demodulation (1006) and descrambling (1008) operations on the extracted signal, and then demultiplexes each physical channel through demultiplexing (1010). The demultiplexed signal is classified into a PCFICH block 1016, a PDCCH block 1024, and a PDSCH block 1032 for each physical channel.

The control format indication channel block (PCFICH block) 1016 is channel decoding (1012) the received PCFICH to obtain a CFI (Acquire CFI; 1024). The CFI is input to a carrier aggregation controller 1018, and the carrier aggregation controller 1018 controls the OFDM signal receiver 1002 using the CFI. Accordingly, the PDCCH and PDSCH reception operations for each component carrier of the UE can be adjusted.

The downlink control channel block (PDCCH block) 1024 may de-rate match (1018) the received PDCCH and channel decode (1020) to obtain a DCI (1022). The DCI is input to the carrier combining controller 1018, and the carrier combining controller 1018 controls the PDSCH reception operation for each component carrier of the terminal by controlling the OFDM signal receiver 1002 using the input DCI.

The downlink data channel block (PDSCH block) 1032 reverse-matches the received PDSCH 1026 and decodes the channel 1028 to obtain data 1030. As described above, data is input to the carrier combining controller 1018, and the carrier combining controller 1018 controls the OFDM signal receiver 1002 using the input data to perform PDCCH and PDSCH reception operations for each component carrier of the terminal. Adjust

The embodiments of the present invention disclosed in the specification and the drawings are only specific examples to easily explain the technical contents of the present invention and aid the understanding of the present invention, and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

Claims (8)

In the data transmission method of the base station,
Configuring the control information transmission interval information of the first component carrier through radio resource control signaling and transmitting it through a downlink data channel of the second component carrier;
Transmitting a downlink control channel for scheduling a downlink data channel of the first component carrier through the second component carrier;
And configuring a downlink data channel of the first component carrier according to the scheduling information of the downlink control channel and transmitting it through the first component carrier. The method of claim 1, wherein the radio resource control signaling is
And adding a carrier indicator to indicate the control information transmission interval information for the first component carrier. The method of claim 1,
The first component carrier is a component carrier with a bad channel environment,
And the second component carrier is a component carrier having a good channel environment. The method of claim 1,
The first component carrier transmits a downlink control channel of the femto cell,
The second component carrier transmits a downlink control channel of a macro cell. In the data receiving method of the terminal,
Acquiring control information transmission interval information of the first component carrier from a downlink data channel received through the second component carrier;
Receiving, via the second component carrier, a downlink control channel for scheduling a downlink data channel of the first component carrier according to the control information transmission interval information;
Receiving the downlink data channel in the first component carrier according to the scheduling information of the received downlink control channel. A carrier combining controller for determining whether to combine the carrier and whether to transmit the scheduling information through the first and second component carriers when the carrier is coupled to the terminal to be scheduled;
A scheduler for inputting control information transmission interval information on a component carrier to transmit scheduling information determined through the carrier combining controller;
A control format indication channel block for formatting control information transmission section information inputted from the scheduler according to a control format indication channel transmission format;
And an OMD signal generator for generating the signal to be transmitted to the terminal when the control information transmission section information is multiplexed. The method of claim 6,
And a downlink data channel block in which the control information transmission section information comprises radio resource control signaling. A control format instruction channel block for channel decoding the control format instruction channel to obtain control information transmission interval information;
A downlink control channel block for obtaining downlink scheduling information for adjusting a downlink data channel reception operation through the control information transmission interval information;
A downlink data channel block for obtaining data from a downlink data channel received through the downlink scheduling information;
And an OMD signal receiver for receiving the downlink control channel and the downlink data channel for each component carrier.

Images