WO2013042991A1

WO2013042991A1 - Method and apparatus for dynamically transmitting control information in wireless communication system

Info

Publication number: WO2013042991A1
Application number: PCT/KR2012/007601
Authority: WO
Inventors: Si Hyung Kim; Dong Hyun Park; Kyoung Min Park
Original assignee: Pantech Co., Ltd.
Priority date: 2011-09-23
Filing date: 2012-09-21
Publication date: 2013-03-28
Also published as: KR20130032798A

Abstract

There are provided a method and apparatus of receiving control information by a user equipment in a wireless communication system. The invention includes receiving system information including information on a TDD (Time Division Duplex) uplink/downlink (UL/DL) configuration from a base station, receiving DCI (Downlink Control Information) including TDD configuration indication information indicating the information on the TDD UL/DL configuration to be changed from the base station through a PDCCH (Physical Downlink Control Channel), and changing the TDD UL/DL configuration based on the TDD configuration indication information. Data traffic may be efficiently controlled by changing the TDD UL/DL configuration in a dynamic and flexible manner. In particular, more effective data traffic control may be achieved for cross-carrier scheduling that independently adopts a TDD UL/DL configuration per serving cell.

Description

METHOD AND APPARATUS FOR DYNAMICALLY TRANSMITTING CONTROL INFORMATION IN WIRELESS COMMUNICATION SYSTEM

The present invention relates to wireless communication, and more specifically to a method and apparatus of dynamically transmitting control information for changing uplink and downlink configuration in a TDD system among wireless communication systems.

A scheme needs that distinguishes wireless resources used for downlink transmission from wireless resources, such as frequency, time, and code regions, used for uplink transmission, so that the wireless resources for downlink transmission do not overlap the wireless resources for uplink transmission. Such scheme is called "duplex". Like in the multiple access scheme to distinguish different users from each other, distinction between the uplink and the downlink may be made in terms of frequency, time, and code regions. The duplex schemes are generally categorized into FDD (Frequency Division Duplexing) schemes, which differentiate the uplink from the downlink in terms of frequency, and TDD (Time Division Duplexing) schemes, which differentiate the uplink from the downlink in terms of time.

Since in the FDD schemes the uplink and the downlink are differentiated from each other in the frequency domain, transmission of data between the base station and the terminal may be continuously performed in the time domain through each link. In the FDD schemes, the same size of frequencies are symmetrically assigned to the uplink and the downlink, so that the FDD schemes have been adopted a lot for symmetric services, such as voice call services. However, the TDD schemes are relatively more appropriate for asymmetric services, such as Internet services, and thus, research on the TDD schemes are actively in progress.

The TDD schemes may assign different ratios of time slots to the uplink and the downlink, respectively, and are thus more appropriate for asymmetric services. Further, since in the TDD schemes the uplink and the downlink are transmitted/received in the same frequency band, the uplink and the downlink are substantially identical in channel state to each other. Accordingly, once a signal is received, the channel state may be estimated right away, which makes this scheme fit for array antenna technologies. The TDD schemes use the entire frequency band for uplink and downlink while differentiating the uplink from the downlink in the time domain. In other words, the TDD schemes use the frequency band for uplink for a predetermined time, and uses the same for downlink for another predetermined time. This design makes it difficult for the base station and the terminal to perform data communication at the same time. In this connection, the terminal and the base station previously define and follow TDD uplink/downlink configuration on whether to use the frequency band for uplink or downlink during a predetermined time.

In the TDD system, however, the fixed TDD uplink/downlink configuration causes it difficult to effectively use resources. Currently, the TDD uplink/downlink configuration is transmitted through system information and statically or semi-statically changed.

It is recently proved that dynamic use of TDD uplink/downlink configuration profits more. There is a need for a method of changing the TDD uplink/downlink configuration so that the TDD uplink/downlink configuration may be dynamically used.

An object of the present invention is to provide a method and apparatus of transmitting control information for changing TDD uplink/downlink configuration.

Another object of the present invention is to reduce overhead that occurs upon transmitting control information for changing TDD uplink/downlink configuration.

According to an aspect of the present invention, a method of receiving control information by a mobile station in a wireless communication system includes the steps of receiving system information including information on a TDD (Time Division Duplex) uplink/downlink (UL/DL) configuration from a base station, receiving DCI (Downlink Control Information) including TDD configuration indication information indicating the information on the TDD UL/DL configuration to be changed from the base station through a PDCCH (Physical Downlink Control Channel), and changing the TDD UL/DL configuration based on the TDD configuration indication information.

The method may further include the step of transmitting data to the base station based on the changed TDD UL/DL configuration.

The TDD configuration indication information may be an indicator that includes a plurality of bits, and the plurality of bits each may indicate whether a different subframe is an uplink or a downlink.

A format of the DCI may be DCI format 1A, and the TDD configuration indication information may be included in a HARQ (Hybrid Automatic Repeat request) process number of the DCIT format 1A.

The DCI may be detected using a TDD configuration radio network temporary identity transmitted through a common search space, and the TDD configuration radio network temporary identity may have one of FFF4 to FFFC.

The TDD configuration indication information may be a one-bit indicator, and the one-bit indicator indicates whether a sixth subframe of a radio frame received by the mobile station is a downlink or an uplink.

The system information may further include information on a period during which the TDD configuration indication information is transmitted.

According to another aspect of the present invention, a method of transmitting control information by a base station in a wireless communication system may include the steps of transmitting system information including information on a TDD UL/DL configuration to a mobile station, transmitting DCI including TDD configuration indication information indicating information on the TDD UL/DL configuration to be changed to the mobile station through a PDCCH, and receiving data from the mobile station based on the TDD UL/DL configuration changed based on the TDD configuration indication information.

According to still another aspect of the present invention, a mobile station of receiving control information in a wireless communication system may include a receiving unit that receives information including information on a TDD (Time Division Duplex) uplink/downlink (UL/DL) configuration from a base station and receives DCI (Downlink Control Information) including TDD configuration indication information indicating the information on the TDD UL/DL configuration to be changed from the base station through a PDCCH (Physical Downlink Control Channel) and a process that changes the TDD UL/DL configuration based on the TDD configuration indication information.

According to yet still another aspect of the present invention, a base station that transmits control information in a wireless communication system may include a process that configures DCI including TDD configuration indication information indicating information on a TDD UL/DL configuration to be changed, a transmitting unit that transmits system information including the information on the TDD UL/DL configuration to a mobile station and transmits DCI including the TDD configuration indication information to the mobile station through a PDCCH, and a receiving unit that receives data from the mobile station based on the TDD UL/DL configuration changed based on the TDD configuration indication information.

According to the present invention, in case that there are present both a user with high UL capacity and another user with high DL capacity in a cell, resources may be properly distributed according to data traffic.

According to the present invention, data traffic may be efficiently controlled by changing TDD UL/DL configuration in a dynamic and flexible manner. In particular, data traffic may be more efficiently controlled for cross-carrier scheduling to which independent TDD UL/DL configuration applies per serving cell.

Fig. 1 illustrates a wireless communication system according to the present invention.

Fig. 2 illustrates an exemplary structure of a protocol according to the present invention.

Fig. 3 illustrates a TDD radio frame according to the present invention.

Fig. 4 illustrates an example of a resource grid for one slot according to the present invention.

Fig. 5 illustrates a structure of a downlink subframe according to the present invention.

Fig. 6 illustrates a structure of an uplink subframe according to the present invention.

Fig. 7 illustrates a time point when a change in TDD UL/DL configuration information applies according to the present invention.

Fig. 8 illustrates that five-bit TDD configuration indication information is transmitted according to the present invention.

Fig. 9 illustrates assigning TDD configuration indication information to a predetermined region of a radio frame and transmitting the TDD configuration indication information.

Fig. 10 illustrates indicating the dynamic TDD UL/DL configuration information using the CFI value according to the present invention.

Fig. 11 illustrates changing a TDD UL/DL configuration by a mobile station according to the present invention.

Fig. 12 illustrates changing a TDD UL/DL configuration by a base station according to the present invention.

Fig. 13 is a block diagram illustrating a mobile station and a base station according to an embodiment of the present invention.

Hereinafter, some embodiments will be described in detail with reference to the accompanying drawings. The same reference notations may be used to refer to the same or similar elements throughout the drawings. When determined to make the gist of the invention unclear, the detailed description of the known configurations or functions will be omitted.

Throughout the specification, the terms "first", "second", "A", "B", "(a)", and "(b)" may be used to describe the components. Such terms are used to distinguish one component from another and should not be construed as limiting the order, sequence, or essence of the components. When a component is referred to as being "connected with", "coupled with", or "combined with" another component, it can be directly connected, coupled, or combined with the other component or intervening components may be present.

Referring to Fig. 1, the wireless communication system 10 is widely arranged to provide various communication services, such as voice, packets, or data. The wireless communication system 10 includes at least one base station (BS) 11. Each base station 11 provides communication services to

specific cells

15a, 15b, and 15c. The cell may be divided into a plurality of regions (referred to as sectors).

The mobile station (MS) 12 may be stationary or mobile, and may be referred to by other terms, such as UE(user equipment), MT(mobile terminal), UT(user terminal), SS(subscriber station), wireless device, PDA(personal digital assistant), wireless modem, or handheld device. The base station 11 may be referred to by other terms, such as eNB (evolved-NodeB), BTS (Base Transceiver System), access point, femto-base station, home nodeB, or relay. The cell should be collectively construed to represent a partial region that is covered by the base station 11 and in meaning covers various coverage regions, such as a mega cell, macro cell, micro cell, pico cell, or felto-cell.

Hereinafter, the downlink refers to communication from the base station 11 to the mobile station 12, and the uplink refers to communication from the mobile station 12 to the base station 11. In the downlink, the transmitter may be part of the base station 11, and the receiver may be part of the mobile station 12. In the uplink, the transmitter may be part of the mobile station 12, and the receiver may be part of the base station 11. The multiple access scheme used in the wireless communication system is not limited to a specific one, but rather may include various ones, such as CDMA(Code Division Multiple Access), TDMA(Time Division Multiple Access), FDMA(Frequency Division Multiple Access), OFDMA(Orthogonal Frequency Division Multiple Access), SC-FDMA(Single Carrier-FDMA), OFDM-FDMA, OFDM-TDMA, OFDM-CDMA. The uplink transmission and downlink transmission may adopt TDD (Time Division Duplex) that uses different time periods for transmission or FDD (Frequency Division Duplex) that uses different frequencies for transmission.

Referring to Fig. 2, a common MAC (Medium Access Control) entity 210 manages a physical layer 220 that uses a plurality of carriers. An MAC message transmitted through a specific carrier may be applied to other carriers. That is, the MAC message is a message that may control the other carriers including the specific carrier. The physical layer 220 may operate in TDD (Time Division Duplex) and/or FDD (Frequency Division Duplex). There are some physical control channels used in the physical layer 220. PDCCH (Physical Downlink Control Channel) informs the mobile station of resource allocation of PCH (Paging Channel) and DL-SCH (Shared Channel) and information on HARQ (Hybrid Automatic Repeat Request) associated with DL-SCH. PDCCH may transport an uplink grant that informs the mobile station of resource allocation of uplink transmission. PCFICH (Physical Control Format Indicator Channel) informs the mobile station of the number of OFDM symbols used for PDCCHs and is transmitted per subframe. PHICH (Physical Hybrid ARQ Indicator Channel) carriers HARQ ACK/NACK signals in response to uplink transmission. PUCCH (Physical Uplink Control Channel) carriers HARQ ACK/NACK for the downlink transmission, scheduling request, and uplink control information, such as CQI. PUSCH (Physical Uplink Shared Channel) transports UL-SCH. PRACH (Physical Random Access Channel) transports a random access preamble.

Fig. 3 illustrates a TDD radio frame according to the present invention.

Referring to Fig. 3, one radio frame is 10ms long and consists of two half-frames each having a length of 5ms. Further, one half-frame consists of five subframes each having a length of 1ms. One subframe is designated as one of an uplink subframe (UL subframe), a downlink subframe (DL subframe), and a special subframe. One TDD radio frame includes at least one uplink subframe, at least one downlink subframe, and at least one special subframe.

One subframe consists of two slots. For example, the length of one subframe is 1ms, and the length of one slot is 0.5ms. A time taken to transmit one subframe is referred to as TTI (Transmission Time Interval). One slot includes a plurality of OFDM Orthogonal Frequency Division Multiplexing) symbols in the time domain and a plurality of subcarriers in the frequency domain. The OFDM symbols are to represent one symbol period since 3GPP LTE uses OFDMA in the downlink, and according to the type of multiple access, are referred to as SC-FDMA symbols or symbol sections. The resource block (RB) is a unit for resource allocation and includes a plurality of OFDM symbols and a plurality of subcarriers in one slot.

The above-described radio frame structure is merely an example, and the number of subframes included in the radio frame or the number of slots included in the subframe, and the number of OFDM symbols included in the slot may vary.

The special subframe is a specific period that separates the uplink from the downlink between the uplink subframe and the downlink subframe. One radio frame includes at least one special subframe, which includes DwPTS (Downlink Pilot Time Slot), guard period (GP), and UpPTS (Uplink Pilot Time Slot). DwPTS is used for initial cell searching, synchronization, or channel estimation. UpPTS is used for channel estimation in the base station and uplink transmission synchronization of mobile station. GP is a protection section to remove interference that occurs in the uplink due to a multi-path delay of the downlink signal between the uplink and the downlink. Meanwhile, the special subframe may be used for downlink subframe.

Referring to Fig. 4, one downlink slot includes a plurality of OFDM symbols in the time domain. Here, for example, one downlink slot includes seven OFDM symbols, and one resource block includes twelve subcarriers in the frequency domain, but is not limited thereto. Here, the uplink slot may include six OFDM symbols according to the expanded CP length.

Each element on the resource grid is referred to as resource element, and one resource block includes 12x7 (=84) resource elements. The number of resource blocks included in the downlink slot is dependent upon the downlink transmission bandwidth set in the cell.

Referring to Fig. 5, the subframe includes two slots. For example, the first three maximum OFDM symbols of the first slot in the subframe correspond to a control region to which control channels are assigned, and the remaining OFDM symbols may be a data region to which PDSCH (Physical Downlink Shared Channel) is assigned.

The downlink control channels include PCFICH, PDCCH(Physical Downlink Control Channel), and PHICH(Physical Hybrid-ARQ Indicator Channel). PCFICH transmitted through the first OFDM symbol in the subframe carries information on the number of OFDM symbols (that is, size of control region) used for transmission of control channels in the subframe.

PDCCH may carry resource allocation of DL-SCH (Downlink-Shared Channel) (which is also referred to as DL grant) and transmission format, resource allocation information of UL-SCH (Uplink Shared Channel) (which is also referred to as UL grant), paging information on PCH, system information on DL-SCH, resource allocation of upper layer control message, such as random access response transmitted on PDSCH, set of transmission power control commands for individual mobile stations in some mobile station group and activation of VoIP (Voice over Internet Protocol). As described above, control information transmitted on PDCCH is referred to as downlink control information (DCI). DCI indicates uplink resource allocation information, downlink resource allocation information, and uplink transmission power control command for some mobile station group. PHICH carries ACK/NACK signals on uplink HARQ. That is, ACK/NACK signals on the uplink data transmitted by the mobile station are transmitted on PHICH.

The downlink subframe may be set as a non-detective subframe in which the mobile station does not attempt to detect data (for example, neither detects a reference signal nor performs reference signal measurement). The non-detective subframe may be, for example, a MBSFN(Multicast/Broadcast Single Frequency Network) subframe.

The MBSFN subframe may be used for two purposes. The first purpose is for MBMS (Multimedia Broadcast Multicast Service). MBMS is a service in which several cells in the wireless communication system simultaneously transmit the same signal. The signals for MBMS are simultaneously transmitted from the several cells, and thus should have a different reference signal inserting scheme from that of unicast in which cells transmit different types of data. For this, the base station informs the mobile station of the position of the subframe through which the MBMS signal is transmitted, wherein the corresponding subframe uses a different reference signal inserting scheme from that of the unicast.

The second purpose is to stop unnecessary signal receiving operation and reference signal measurement from being performed to the mobile station connected to the base station or relay. For example, in 3GPP LTE, when failing to receive any signal including the reference signal in the specific subframe, the mobile station may cause malfunctions. To prevent this, the relay sets the subframe for receiving downlink data from the base station as the MBSFN subframe and notifies this to the mobile station. Then, the mobile station (more specifically, 3GPP LTE release-8 mobile station) does not detect the reference signal in the MBSFN subframe nor does it perform the reference signal measurement.

A plurality of PDCCHs may be transmitted in the control region, and the mobile station may monitor the plurality of PDCCHs. The PDCCHs are transmitted over an aggregation of one or some consecutive CCEs (control channel elements). CCE is a logical allocation unit used to provide an encoding rate according to the state of wireless channel to PDCCH. CCE corresponds to a plurality of resource element groups. According to the relationship between the number of CCEs and encoding rate provided by the CCEs, the format of PDCCH and the number of bits of available PDCCHs are determined.

The control information transmitted through PDCCH is referred to as downlink control information (DCI), and there are various formats of DCI as follows.

Table 1

DCI format	Description
0	Used for scheduling PUSCH(uplink grant)
1	Used for scheduling one PDSCH codeword in one cell
1A	Used for compact scheduling of one PDSCH codeword in one cell and random access procedure initialized by PDCCH command
1B	Used for compact scheduling of one PDSCH codeword in one cell using precoding information
1C	Used for compact scheduling of one PDSCH codeword and notification of change in MCCH
1D	Used for compact scheduling of one PDSCH codeword in one cell including precoding and power offset information
2	Used for PDSCH scheduling on mobile station configured in spatial multiplexing mode
2A	Used for PDSCH scheduling of mobile station configured in large delay CCD mode
2C	Used for transmission mode 9 (multi-layer transmission)
3	Used for transmission of TPC command for PUCCH and PUSCH including two-bit power adjustment
3A	Used for transmission of TPC command for PUCCH and PUSCH including single-bit power adjustment
4	Used for PUSCH scheduling in one uplink cell using multi-antenna port transmission mode

Referring to Table 1, there are provided DCI format 0 indicating uplink resource allocation information, DCI format 1 for scheduling of one PDSCH codeword, DCI format 1A for compact scheduling of one PDSCH codeword, DCI format 1C for very compact scheduling of DL-SCH, DCI format 2 for PDSCH scheduling in closed-loop spatial multiplexing mode, DCI format 2A for PDSCH scheduling in open-loop spatial multiplexing mode, and DCI formats 3 and 3A for transmission of TPC (Transmission Power Control) command for uplink channel.

Each field of DCI is sequentially mapped to n information bits a₀ to a_n-1. For example, if DCI is mapped with a total of 44 information bits, each field of DCI is sequentially mapped to a₀ to a_n-1. DCI formats 0, 1A, 3, and 3A all may have the same payload size. DCI format 0 may be also referred to as uplink grant.

The following table represents an example of information elements included in DCI format 0 which is uplink resource allocation information (or uplink grant). DCI format 0 may be constituted of at least one of the information elements, doesn't have to include all the information elements.

Table 2

The following table represents the structure of a radio frame that may be configured according to the arrangement of the uplink subframe and downlink subframe in the 3GPP LTE TDD system, which is referred to as TDD UL/DL configuration. In Table 3, 'D', 'U', and 'S', respectively, represent the downlink subframe, uplink subframe, and special subframe.

Table 3

A time point when the downlink switches to the uplink or when the uplink switches to the downlink is referred to as switching point. The DL/UL switch-point periodicity refers to a period at which the same aspect of switch between the uplink subframe and the downlink subframe repeats, and this may be 5ms or 10ms. For example, when viewed in the UL-DL configuration 0, from the 0^th subframe to the fourth subframe, a switch is made like D->S->U->U->U, and from the fifth subframe to the ninth subframe, a switch is made like D->S->U->U->U like the previous switch. Since one subframe is 1ms long, the switch-point periodicity is 5ms. In other words, the switch-point periodicity is shorter than one radio frame length (10ms) and the switching aspect in the radio frame repeats once.

The base station or relay may set the downlink subframe as MBFSN subframe and may transmit and receive data. In such case, there is a subframe that may not be set as the MBSFN subframe. For example, in case that the wireless communication system is a 3GPP LTE sysem, i) when the wireless communication system operates in TDD mode, subframes #0, #1, #5, and #6 may not be set as the MBSFN subframe, and when the wireless communication system operates in FDD mode, subframes #0, #4, #5, and #9 may not be set as the MBSFN subframe. This is why such subframes are subframes that transmit main control signals, such as synchronization signals (for example, primary synchronization signal, secondary synchronization signal), to the mobile station.

Referring to Fig. 6, the uplink subframe may be divided into a control region and a data region in the frequency domain. The control region is assigned with PUCCH through which uplink control information is transmitted. The data region is assigned with PUSCH through which data is transmitted.

For one mobile station, the PUCCH is assigned as a resource block pair in the subframe. The resource blocks in the resource block pair take up different subcarriers, respectively, in the first and second slots. The frequencies occupied by the resource blocks belonging to the resource block pair assigned to the PUCCH are changed with respect to a slot boundary. This is referred to as the RB pair assigned to the PUCCH being frequency-hopped at the slot boundary. The mobile station may obtain a frequency diversity gain by transmitting uplink control information through different subcarriers over time.

The uplink control information transmitted on PUCCH may include HARQ ACK/NACK, CQI (Channel Quality Indicator) indicating the channel state of downlink, and SR (Scheduling Request) that is an uplink wireless resource allocation request.

PUSCH is mapped with UL-SCH that is a transport channel. The uplink data transmitted on PUSCH may be a transport block that is a data block for UL-SCH transmitted during TTI. The transport block may be user information. Or, the uplink data may be multiplexed data. The multiplexed data may be obtained by multiplexing the transport block for UL-SCH with control information. For example, the control information multiplexed with the data may include CQI, PMI (Precoding Matrix Indicator), HARQ, and RI (Rank Indicator). Or, the uplink data may be constituted of only the control information.

According to the present invention, a method and apparatus of dynamically changing a TDD UL/DL configuration are now described. Efficient data traffic control may be possible by changing the TDD UL/DL configuration in a dynamic and flexible manner. In particular, in case that an independent TDD UL/DL configuration applies to each serving cell and cross-carrier scheduling applies, this works better.

Basically, the TDD UL/DL configuration information is transmitted through system information (SI), such as SIB1. At this time, a field (TDD-Config) included in the system information may vary at the period of the minimum of 640ms. Specifically, the TDD-config field is changed by modificationPeriodCoeff of BCCH-Config in RadioResourceConfigCommon of system information SIB2, and the minimum value of the period of such change is 64 frames (=640ms). Accordingly, there is suggested a method for dynamically changing the TDD UL/DL configuration. According to the present invention, any ambiguity may be removed that may be caused upon allowing the mobile stations in the cell to recognize the TDD configuration information and it may be possible to more easily inform the mobile stations of the TDD configuration information.

Fig. 7 illustrates a time point when a change in TDD UL/DL configuration information applies according to the present invention. Different types of hatching in Fig. 7 indicate different types of system information.

Referring to Fig. 7, when a notification that system information is to be changed is transmitted to the mobile station during a specific section (for example, 640ms), the system information updated during the specific section is transmitted after the specific section. Here, the specific section may be a BCCH changing section for changing the system information. In other words, the mobile station receives the notification regarding the change in system information during the BCCH changing section (n) and then obtains new system information changed/updated during a next BCCH changing section (n+1). Meanwhile, the mobile station operates with the previously obtained system information until the mobile station obtains the new system information. According to the present invention, the system information further includes TDD UL/DL configuration information and in addition to the TDD UL/DL configuration information may include other information necessary in the cell.

As a scheme for dynamically changing the TDD UL/DL configuration according to the present invention, a table is provided which defines the TDD UL/DL configuration information. The table and predefined information transmission timing should be previously known between the base station and the mobile station.

Further, the changed TDD UL/DL configuration may apply from the next radio frame after the dynamic TDD UL/DL configuration information comes down. Or, the changed TDD UL/DL configuration may apply a predetermined period after the dynamic TDD UL/DL configuration information comes down.

First, TDD configuration indication information that indicates a new TDD UL/DL configuration to be changed is described. The TDD configuration indication information is dynamically transmitted so that the TDD UL/DL configuration is flexibly changed.

Presently referring to Table 4, there are seven TDD UL/DL configurations #0 to #6, and thus, three-bit TDD configuration indication information is used to report the TDD UL/DL configuration number (or index) shown in Fig. 3. That is, Table 4 shows an example of the three-bit TDD configuration indication information.

Table 4

TDD configuration	3 bits
0	000
1	001
2	010
3	011
4	100
5	101
6	110
7(reserved)	111

The following Table 5 shows another example of the three-bit TDD configuration indication information.

Table 5

TDD configuration	3 bits
Default(No change)	000
0	001
1	010
2	011
3	100
4	101
5	110
6	111

Here, "default" means that there is no change in TDD configuration. That is, the TDD UL/DL configuration used for the previous frame is applied as is. On the other hand, the remaining three-bit indication information other than the default is used to indicate the changed TDD UL/DL configuration.

As another example, five-bit TDD configuration indication information may be used to indicate the TDD UL/DL configuration to be changed. Fig. 8 illustrates that five-bit TDD configuration indication information is transmitted according to the present invention.

Referring to Fig. 8, in each TDD configuration of Table 3, each subframe #0 is a DL subframe, each subframe #1 a special subframe, each subframe #2 a UL subframe, each subframe #5 a DL subframe, and each subframe #6 a special subframe (or DL subframe). Accordingly, the subframes may be deemed to have fixed features irrespective of the TDD configuration number.

Accordingly, the mobile station may follow the TDD UL/DL configurations shown in Table 3, which are known through the system information with respect to subframes #0, #1, #2, #5, and #6, and may make changes to the features of subframes #3, #4, #7, #8, #9. At this time, the TDD configuration may be changed through the five-bit indication information that indicates the characteristic of each of subframes #3, #4, #7, #8, #9. Further, other than the TDD UL/DL configurations shown in Table 3, various types of UL/DL traffic may be adjusted.

The following table shows an example of five-bit TDD configuration indication information.

Table 6

Subframe #3	subframe #4	subframe #7	subframe #8	subframe #9	5bits
UL	UL	UL	UL	UL	00000
DL	UL	UL	UL	UL	00001
DL	DL	UL	UL	UL	00011
DL	DL	DL	UL	UL	00111
…	…	…	…	…	…

Here, it may be indicated by a bitmap scheme whether a subframe is a DL subframe or UL subframe. The five-bit indication information may be set so that the bit for UL subframe is '0' and the bit for the DL subframe is '1'. On the contrary, the five-bit indication information may be set so that the bit for the UL subframe is '1' and the bit for the DL subframe is '0'. As an example, in Table 6, bits are assigned to the right from a lower subframe number. As another example, the TDD UL/DL configuration to be changed may be indicated by using two-bit TDD configuration indication information.

The TDD UL/DL configurations may be separated into TDD UL/DL configurations whose switch-point periodicity is 5ms and TDD UL/DL configurations whose switch-point periodicity is 10ms as shown in Table 3. In Table 3, for all the TDD UL/DL configurations, subframe #6 is set as the DL subframe or special subframe. For a UL subframe to be present after subframe #6, subframe #6 should be set as a special subframe. This is why in case of switching from DL transmission to UL transmission, a guard period is inevitably required. Accordingly, depending on whether subframe #6 is a special subframe or DL subframe, the changeable TDD UL/DL configuration is restricted. Further, in case that subframe #6 is a special subframe, the switch-point periodicity is set as 5ms, and in case that subframe #6 is a DL subframe, the switch-point periodicity is set as 10ms.

As such, depending on the switch-point periodicity, each piece of TDD configuration indication information may be determined. The following table shows an example of two-bit TDD configuration indication information in case that the switch-point periodicity is 5ms.

Table 7

TDD UL/DL Configuration	2 bits
0	00
1	01
2	10
6	11

The following table shows an example of two-bit TDD configuration indication information in case that the switch-point periodicity is 10ms.

Table 8

TDD UL/DL Configuration	2 bits
3	00
4	01
5	10
7(Reserved)	11

In this case, the TDD UL/DL configurations may be changed only between the TDD UL/DL configurations having a periodicity of 5ms, and the TDD UL/DL configurations may be changed only between the TDD UL/DL configurations having a periodicity of 10ms. For example, in case of TDD UL/DL configuration #0, if the two-bit TDD configuration indication information has a value of 10, the TDD UL/DL configuration to be changed is #2, and in case of TDD UL/DL configuration #4, if the two-bit TDD configuration indication information has a value of 10, the TDD UL/DL configuration to be changed is #5.

Additionally, the present invention may determine each TDD configuration indication information in the group that is set according to the switch-point periodicity. Here, separate information may be further added to indicate the switch-point periodicity. That is, at least one or more bits of separate information may be provided to indicate whether the switch-point periodicity is 5ms or 10ms. Then, the indication information shown in Table 7 or 8 for changing the TDD UL/DL configuration in the same group may be set and notified to the mobile station. As described above, one reason for dynamically changing the TDD UL/DL configuration is to properly use a TDD UL/DL configuration with many UL subframes and a TDD UL/DL configuration with many DL subframes depending on data traffic in case a user with high UL capacity and another user with high DL capacity are both present in the cell. Accordingly, changes may be made between the TDD UL/DL configurations separated depending on switch-point periodicity so that the TDD UL/DL configurations may have various rates, and thus, various types of data traffic may be supported by using the two-bit indication information. That is, a required type of subframe may be dynamically applied as necessary.

For example, in case switch-point periodicity is 5ms, the UL ratio is 60% for TDD UL/DL configuration #0, 40% for TDD UL/DL configuration #1, 20% for TDD UL/DL configuration #2, and 50% for TDD UL/DL configuration #6, and thus, dynamically changing the TDD UL/DL configuration is more effective rather than using only one TDD UL/DL configuration.

Here, what is shown in Tables 7 and 8 is merely an example, and according to the TDD configuration, it may be possible to have other values match the two-bit indication information.

As another example, the TDD UL/DL configuration to be changed may be indicated by using one-bit TDD configuration indication information. The TDD UL/DL configuration may be dynamically changed only for the predetermined specific subframe number.

In case that the number of specific subframes to be changed is1, the TDD UL/DL configuration may be changed by one-bit TDD configuration indication information. At this time, the bitmap scheme may be used. In case the specific subframe is changed to the UL subframe, the TDD configuration indication information may be set as '0', and in case the specific subframe is changed to the DL subframe, the TDD configuration indication information may be set as '1'. On the contrary, in case the specific subframe is changed to the UL subframe, the TDD configuration indication information may be set as '1', and in case the specific subframe is changed to the DL subframe, the TDD configuration indication information may be set as '0'.

As an example, the specific subframe may be determined as follows. The TDD UL/DL configuration information may be transmitted only at a specific timing (e.g., specific subframe) at a specific period, and the mobile station may detect the TDD UL/DL configuration information only at the specific timing. At this time, since in all the TDD UL/DL configurations in Table 3, subframes #0, #1, #5, and #6 are always set as the DL subframes or specific subframes, the specific timing may be selected among subframes #0, #1, #5, and #6. Further, it is more appropriate to, among subframes #0, #1, #5, and #6, always select subframes #0 and #5 which are DL subframes. In particular, since MIB (Master Information Block) is transmitted through subframe #0 per subframe, subframe #5 may be the optimal transmission subframe. Accordingly, in case that the one-bit TDD configuration indication information indicates TDD configuration regarding subframe #5, it may be effective. The MIB may be transmitted through BCCH, which may be mapped with BCH and PBCH.

Similarly, in case the number of specific subframes to be changed is n, n pieces of one-bit TDD configuration indication information may be used.

Whether some subframe is a specific subframe to be changed may be previously fixed according to each TDD UL/DL configuration or may be separately indicated by using cell-specific information (for example, system information).

As another example, the changeable TDD UL/DL configuration may be previously determined as the TDD UL/DL configuration having the largest difference in ratio between DL and UL based on each TDD UL/DL configuration that is set as the system information, and according to the TDD configuration indication information, may be changed to the predetermined TDD UL/DL configuration.

The following table shows previously determining the TDD configurations to be changed by using one-bit TDD configuration indication information.

Table 9

TDD UL/DL configuration	When one-bit TDD configuration indication information is set, new TDD UL/DL configuration
0	2
1	5
2	0
3	0
4	6
5	0
6	5

For example, if one-bit TDD configuration indication information is set in TDD UL/DL configuration #0 (e.g., if '1' or '0'), the TDD configuration to be changed is #2. Of course, according to an embodiment of the present invention, in Table 9, the TDD UL/DL configuration and the new TDD UL/DL configuration when the one-bit TDD configuration indication information is set may match each other with different combinations.

A method of transmitting the TDD configuration indication information determined in Tables 4 to 9 is now described.

As an example, the TDD configuration indication information may be included in a DCI format (in particular, DCI format 1A) and transmitted to the mobile station. DCI format 1A is a DCI format for compact scheduling of one PDSCH codeword in one cell and a DCI format for random access procedure disclosed according to the PDCCH indication.

In case that the CRC (Cyclic Redundancy Check) of DCI format 1A is scrambled with the cell-specific RNTI, such as SI-RNTI(System Information RNTI), P-RNTI(Paging RNTI) or RA-RNTI(Random Access RNTI), among RNTIs (Radio Network Temporary Identities), and transmitted, four bits of HARQ process number field for TDD in DCI format 1A are not used for other purposes.

Through such four bits assigned to the HARQ process number field in DCI format 1A, the determined TDD configuration indication information may be transmitted. Further, "0000" may be set as a default to indicate that the TDD configuration is not changed.

Further, as in Tables 4, 5, and 7 to 9, in case the TDD configuration indication information has less than four bits, the remaining bits (or fields) are not used but reserved.

Further, in case five-bit TDD configuration indication information is transmitted as in Table 6, it may be reconfigured as four-bit TDD configuration indication information that excludes one specific subframe and may be transmitted by using four bits assigned to the HARQ process number.

As another example, the TDD UL/DL configuration information to be changed may be dynamically transmitted by using a new type of RNTI (hereinafter, "TDD-CFG-RNTI").

The new-type TDD-CFG-RNTI is transmitted through a common search space and thus should be able to be identified by all users. The TDD UL/DL configuration information may be dynamically transmitted through the DCI information detected by TDD-CFG-RNTI.

TDD-CFG-RNTI may use one of "FFF4" to "FFFC". Since "FFF4" to "FFFC" is not used by any RNTI but reserved, TDD-CFG-RNTI may have one of "FFF4" to "FFFC".

As another example, the TDD UL/DL configuration information to be changed may be dynamically transmitted by using a CRC mask for PBCH (Physical Broadcast Channel).

The existing CRC mask for PBCH has three values which indicate the numbers of transmission antenna ports in the base station, which are 1, 2, and 4, respectively.

At this time, three CRC mask values for the TDD UL/DL configuration having different values from the CRC mask values for the existing PBCH are set to indicate TDD UL/DL configuration numbers, respectively. In such case, the CRC mask indicates not the number of transmission antenna ports in the base station but the TDD UL/DL configuration.

In such case, instead of the TDD configuration indication information shown in Tables 4 to 9, the CRC mask for the TDD UL/DL configuration is used. Three TDD UL/DL configurations that may be changed for each TDD UL/DL configuration transmitted through the system information are pre-determined, and is changed to the determined TDD UL/DL configuration indicated in case the CRC mask for the TDD UL/DL configuration is used. At this time, the dynamic TDD UL/DL configuration information may be transmitted only in a specific subframe (or at a specific timing) or at a specific period. At this time, the number of times of decoding may increase only for the mobile station in the specific subframe (or timing) for which the CRC mask for TDD UL/DL configuration is used. This is why more types of CRC masks may be present. That is, if the TDD UL/DL configuration is informed through the CRC mask in all the subframes where PBCH is transmitted, six CRC masks need to be decoded per subframe, while if the CRC mask for the TDD configuration is transmitted at a specific timing, the number of times of decoding increases only at the specific timing, and thus, an influence caused by the increase in the number of times of decoding may be reduced.

Meanwhile, in determining the TDD configuration indicated by the CRC mask for the TDD UL/DL configuration, a TDD UL/DL configuration having a large ratio between UL and DL may be selected as the changeable TDD UL/DL configuration.

The following table shows examples of changeable TDD configurations indicated by the CRC mask for the TDD UL/DL configuration when the TDD UL/DL configuration preset through the system information is TDD configuration #0.

Table 10

TDD UL/DL Configuration	PBCH CRC mask for TDD UL/DL configuration<x_ant,0, x_ant,1,…,x_ant,15>
1	<0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1>
2	<1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0>
5	<1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0>

The changeable TDD UL/DL configurations have been previously determined as TDD UL/DL configurations #1, #2, and #5. This is why the UL subframe ratios of TDD UL/DL configurations #1, #2, and #5 are 40%, 20%, and 10%, respectively, and thus they show a large difference from TDD UL/DL configuration #0 which has a UL subframe ratio of 60%. What is shown in Table 10 is merely an example, and the TDD UL/DL configuration or CRC mask for the TDD UL/DL configuration may have different values.

As another example, a predetermined region (resource block) for transmitting system information (for example, ABS pattern information, and information for carrier aggregation or multi-cooperation wireless communication) may be assigned for the TDD configuration indication information shown in Tables 4 to 9 and may be transmitted.

Referring to Fig. 9, when cell-specific information (e.g., system information) having a period of 10ms (this may vary depending on the dynamic changing period of the TDD configuration) is transmitted, TDD configuration indication information is assigned to the last OFDM symbol of the second slot in subframe #5, i.e., slot #11, and may be transmitted. Of course, the TDD configuration indication information may be assigned to another slot or another OFDM symbol.

As another example, the TDD configuration indication information may be transmitted using CFI (Control Format Indicator) information transmitted through PCFICH without additional signaling.

The CFI information is used to indicate the number of OFDM symbols of the downlink control region and is transmitted per subframe. If the CIF codeword is decoded, CFI value "1", "2", or "3" may be obtained. This indicates that the number of OFDM symbols is 1, 2, or 3. However, since CFI value "4" is not used but reserved, this may be used to dynamically transmit the TDD configuration indication information.

If the CFI value is set as "4", it may be impossible to indicate the number of OFDM symbols. In case the CFI values of consecutive subframes are the same, if the CFI value is set as "4", the corresponding subframe is applied with the CFI value of the previous subframe, thereby solving the problem. In case the CFI values of three or more consecutive subframes are the same, if the CFI value is set as "4", the CFI value of the first subframe among the consecutive subframes is applied as the CFI of the remaining subframes. That is, the TDD configuration indication information may be transmitted only when the CFI values of the consecutive subframes are the same.

Fig. 10 illustrates indicating the dynamic TDD UL/DL configuration information using the CFI value according to the present invention. When in one radio frame the number of subframes whose CFI value is "4" is n, n adds to TDD UL/DL configuration (or TDD UL/DL configuration received through system information) number k of the current radio frame. That is, n+k is the TDD UL/DL configuration number that applies from the next radio frame. If there are M TDD UL/DL configurations, when n+k exceeds M, counting restarts from 0.

Referring to Fig. 10, in the current radio frame, the number of subframes which have TDD UL/DL configuration #4 and CFI value "4" is 4 (i.e., n=4), and n+k is 8. As in Table 3, if there are a total of seven TDD UL/DL configurations, counting restarts from 0 by 1 in excess of 7. Then, the TDD UL/DL configuration that applies from the next radio frame is #0.

Further, the CFI values of subframes #0 and #1 is "3", and the CFI values of subframes #4 and #5 are "4". The CFI value "3" of subframe #1 applies to subframes #4 and #5 whose CFI values are "4", so that the number of OFDM symbols in the downlink control region of subframes #4 and #5 is 3.

Similarly, since the CFI values of subframes #8 and #9 are "4", if the CFI value "1" of subframe #7 applies to subframes #8 and #9, the number of OFDM symbols in the downlink control region of subframes #8 and #9 is 1.

As another example, the period at which the TDD UL/DL configuration changes may be transmitted. The changing period of the TDD UL/DL configuration may be changed for each cell.

Separately from the TDD UL/DL configuration information (hereinafter, "Config_1") transmitted to the mobile station through system information (e.g., S1B1), the TDD UL/DL configuration information (hereinafter, "Config_2") may be dynamically transmitted. In such case, a period at which Config_2 is transmitted to change the TDD UL/DL configuration may be transmitted through separate system information. This is possible by adding parameter (or field) tdd_Config2_Period to the system information, and tdd_Config2_Period may have a value of 10ms, 20ms, 40ms, or 120ms. tdd_Config2_Period may have a value of "0", which means that the dynamic TDD UL/DL configuration is not changed.

The information on Config_2 is maintained only during the period that the TDD UL/DL configuration is cell-specifically and dynamically changed, and unless new Config_2 information is then provided, the mobile station determines the TDD UL/DL configuration based on Config_1.

Further, information on the period at which the TDD UL/DL configuration is dynamically changed per cell may be exchanged with adjacent cells through an X-2 interface.

Referring to Fig. 11, the mobile station receives system information from the base station (S1100). The system information includes TDD UL/DL configuration information. At this time, the system information may be received through one of PDCCH, PBCH, and PCFICH. According to the type of each channel, a different method may be used to change the TDD configuration.

To change the TDD UL/DL configuration, TDD configuration indication information indicating a TDD UL/DL configuration to be changed is received (S1105). However, in case information on the TDD UL/DL configuration to be changed is received together with the system information through PDCCH, PBCH, BCCH, or PCFICH through which the system information is transmitted, step S1105 may be omitted.

The timing that the TDD configuration indication information is received may be different from the timing that the system information is received, and the period may be dynamically determined, such as 10ms or 20ms. The mobile station also receives the TDD configuration indication information through PDCCH, PBCH, BCCH, or PCFICH according to the present invention. The TDD configuration indication information may be set as one of the bits defined as in Tables 4 to 9 according to the present invention.

The TDD configuration indication information may be included in DCI format 1A that is received through PDCCH. In particular, when scrambled with the cell-specific RNTI, it may be received by using the HARQ process number field.

Further, the TDD configuration indication information may be included in the DCI detected by a new type of RNTI according to the present invention and may be transmitted.

Further, the TDD configuration indication information may be transmitted through a CRC mask for PBCH newly configured for the TDD configuration.

Further, the TDD configuration indication information may be assigned to a predetermined region for transmitting the system information and may be transmitted through the assigned region per radio frame. At this time, the system information block (SIB) including the system information may be received through BCCH and the BCCH may be mapped with DL-SCH which may be mapped with PDSCH.

Further, the TDD configuration indication information may be transmitted using CFI transmitted through PCFICH.

Using the TDD configuration indication information, the mobile station changes the TDD UL/DL configuration received through the system information to a new TDD UL/DL configuration (S1110). In case of receiving the TDD configuration indication information through PDCCH, DCI format 1A included in the PDCCH is used to change to the new TDD UL/DL configuration. In case the TDD configuration indication information is included in the DCI detected by the new type of RNTI according to the present invention and is then transmitted, the DCI is decoded to make a change to the new TDD UL/DL configuration. In case the TDD configuration indication information is received through PBCH, a CRC mask for PBCH newly configured for the TDD configuration is decoded to make a change to the new TDD UL/DL configuration. In case the TDD configuration indication information is received through PCFICH, the CFI value transmitted through PCFICH is used to make a change to the new TDD UL/DL configuration.

Data is transmitted and received through the new TDD UL/DL configuration changed by using the TDD configuration indication information (S1115).

Referring to Fig. 12, the base station transmits system information to the mobile station (S1200). The system information includes TDD UL/DL configuration information. The base station configures system information including the TDD configuration indication information defined as in Tables 4 to 9 according to the present invention and transmits the configured system information to the mobile station through BCCH.

To change the TDD UL/DL configuration, TDD configuration indication information indicating the TDD UL/DL configuration to be changed is configured and transmitted (S1205). The TDD configuration indication information may have a timing different from a timing that the system information is transmitted, and the different timing may be dynamically determined, such as 10ms or 20ms. Further, the system information may be transmitted through one of PDCCH, PBCH, and PCFICH. According to the type of each channel, the TDD configuration indication information may be transmitted by a different method.

The TDD configuration indication information may be included in DCI format 1A transmitted through PDCCH. In particular, when scrambled with the cell-specific RNTI, it may be transmitted by using the HARQ process number field.

Further, the TDD configuration indication information may be included in the DCI detected by a new type of RNTI according to the present invention and may be transmitted. The DCI may be also transmitted through PDCCH.

Further, the TDD configuration indication information may be transmitted through PBCH using a CRC mask for PBCH newly configured for the TDD configuration.

Further, the TDD configuration indication information may be assigned to a predetermined region for transmitting the system information and may be transmitted through BCCH using the assigned region.

Further, the TDD configuration indication information may be transmitted using the CFI transmitted through PCFICH.

Data is transmitted and received through the new TDD UL/DL configuration changed using the TDD configuration indication information (S1210).

Referring to Fig. 13, the mobile station 1300 includes a receiving unit 1305, a processor 1310, and a transmitting unit 1320.

The receiving unit 1305 may receive TDD configuration indication information or system information from the base station 1350. The system information may be received through one of BCCH, PDCCH, PBCH, and PCFICH. According to the type of each channel, the TDD configuration may be changed by a different method. A timing that the TDD configuration indication information is received may be different from a timing that the system information is received, and may be dynamically determined, such as 10ms or 20ms. The TDD configuration indication information may be set by one of the bits defined as in Tables 4 to 9 according to the present invention.

The TDD configuration indication information may be received through DCI format 1A of PDCCH. Further, the TDD configuration indication information may be received through DCI detected by a new-type RNTI according to the present invention. Further, the TDD configuration indication information may be received using a CRC mask for PBCH newly configured for the TDD configuration. Further, the TDD configuration indication information may be assigned to a predetermined region for transmitting the system information and may be received through the assigned region per radio frame. Further, the TDD configuration indication information may be received using CFI transmitted through PCFICH.

The processor 1310 may change the TDD UL/DL configuration based on the TDD configuration indication information or the system information.

In case the TDD configuration indication information is received through PDCCH, the processor 1310 may decode DCI format 1A of PDCCH and based on this may change the TDD UL/DL configuration. Further, the processor 1310 may decode the DCI detected by the new-type RNTI according to the present invention and may change the TDD UL/DL configuration based on this.

Further, in case the TDD configuration indication information is received through PBCH, the processor 1310 may change the TDD UL/DL configuration using the CRC mask for the newly configured PBCH for the TDD configuration.

Further, in case the TDD configuration indication information is received through BCCH, the processor 1310 may change the TDD UL/DL configuration by using the TDD configuration indication information assigned to the predetermined region for transmitting the system information transmitted through BCCH.

Further, in case the TDD configuration indication information is received through PCFICH, the processor 1310 may change the TDD UL/DL configuration by using CFI transmitted through PCFICH.

The transmitting unit 1320 transmits data to the base station 1350 based on the changed TDD UL/DL configuration.

The base station 1350 includes a transmitting unit 1355, a receiving unit 1360, and a processor 1370.

The processor 1370 configures TDD configuration indication information that is to be transmitted to the mobile station. The TDD configuration indication information defined as in Tables 4 to 9 according to the present invention is configured, and may be included in the system information. The system information may be configured to be transmitted through one of PDCCH, PBCH, and PCFICH. The TDD configuration indication information may have a timing different from a timing that the system information is transmitted, and may be dynamically determined, such as 10ms or 20ms. The TDD configuration indication information may be configured to be transmitted by a different method according to the type of each channel.

The TDD configuration indication information may be configured to be included in DCI format 1A of PDCCH. Further, the TDD configuration indication information may be configured to be included in DCI detected by new-type RNTI according to the present invention. Further, the TDD configuration indication information may be configured using a CRC mask for PBCH newly configured for the TDD configuration. Further, the TDD configuration indication information may be configured to be assigned to a predetermined region for transmitting the system information. Further, the TDD configuration indication information may be configured using CIF transmitted through PCFICH.

The transmitting unit 1355 may transmit the system information or TDD configuration indication information to the mobile station 1300. The TDD configuration indication information may be transmitted through DCI format 1A of PDCCH. Further, the TDD configuration indication information may be included in DCI detected by the new-type RNTI according to the present invention and transmitted through PDCCH. Further, the TDD configuration indication information may be transmitted through PBCH using a CRC mask for PBCH newly configured for the TDD configuration. Further, the TDD configuration indication information may be assigned to a predetermined region for transmitting the system information and may be transmitted on BCCH through the assigned region per radio frame. Further, the TDD configuration indication information may be transmitted through PCFICH using CFI transmitted on PCFICH.

The receiving unit 1360 receives data from the mobile station 1300 based on the changed TDD UL/DL configuration.

The above description, methods are described by flow chart of several steps or blocks, and tables includes several elements. However, in the present invention, methods and tables don't need to include all the steps and blocks or elements. Those are examples.

The above description is made merely on examples of the technical scope of the invention, and various modifications and variations may be made by those skilled in the art without departing from the gist of the invention. Accordingly, the embodiments are provided not to limit the technical scope of the invention but to describe the invention, and the technical scope of the invention is not limited to the embodiments. The scope of the invention should be interpreted by the appending claims, and all the equivalents of the invention should be construed as being included in the invention.

Claims

A method of receiving control information by a User Equipment (UE) in a wireless communication system, the method comprising the steps of:

receiving system information including information related to a Time Division Duplex uplink/downlink (TDD UL/DL) configuration from a base station;

receiving Downlink Control Information (DCI) including TDD configuration indication information indicating the information related to the TDD UL/DL configuration to be changed from the base station through a Physical Downlink Control Channel (PDCCH); and

changing the TDD UL/DL configuration based on the TDD configuration indication information;

wherein the TDD configuration indication information is comprised of bitmap, and wherein each bit of the bitmap indicate whether a subframe mapping to the each bit is an uplink subframe or a downlink subframe.
The method of claim 1, further comprising the step of transmitting data to the base station based on the changed TDD UL/DL configuration.
The method of claim 1, wherein a format of the DCI is DCI format 1A, and the TDD configuration indication information is included in a HARQ (Hybrid Automatic Repeat request) process number of the DCIT format 1A.
The method of claim 1, wherein the DCI is detected using a TDD configuration radio network temporary identity transmitted through a common search space, and wherein the TDD configuration radio network temporary identity has one of FFF4 to FFFC.
The method of claim 1, wherein the TDD configuration indication information is a one-bit, and the one-bit indicates whether a sixth subframe of a radio frame received by the user equipment is a downlink subframe or an uplink subframe.
The method of claim 1, wherein the system information further includes information on a period during which the TDD configuration indication information is transmitted.
A method of transmitting control information by a base station in a wireless communication system, the method comprising the steps of:

transmitting system information including information on a TDD UL/DL configuration to a user equipment;

transmitting DCI including TDD configuration indication information indicating information on the TDD UL/DL configuration to be changed to the user equipment through a PDCCH; and

receiving data from the user equipment based on the TDD UL/DL configuration changed based on the TDD configuration indication information;

wherein the TDD configuration indication information is comprised of bitmap, and wherein each bit of the bitmap indicate whether a subframe mapping to the each bit is an uplink subframe or a downlink subframe.
The method of claim 7, wherein a format of the DCI is DCI format 1A, and the TDD configuration indication information is included in a HARQ process number of the DCIT format 1A.
The method of claim 7, wherein the DCI is detected using a TDD configuration radio network temporary identity transmitted through a common search space, and wherein the TDD configuration radio network temporary identity has one of FFF4 to FFFC.
The method of claim 7, wherein the TDD configuration indication information is a one-bit, and the one-bit indicates whether a sixth subframe of a radio frame received by the user equipment is a downlink subframe or an uplink subframe.
The method of claim 7, wherein the system information further includes information on a period during which the TDD configuration indication information is transmitted.
A user equipment of receiving control information in a wireless communication system, the user equipment comprising:

a receiving unit that receives information including information on a TDD (Time Division Duplex) uplink/downlink (UL/DL) configuration from a base station and receives DCI (Downlink Control Information) including TDD configuration indication information indicating the information on the TDD UL/DL configuration to be changed from the base station through a PDCCH (Physical Downlink Control Channel); and

a process that changes the TDD UL/DL configuration based on the TDD configuration indication information;

wherein the TDD configuration indication information is comprised of bitmap, and wherein each bit of the bitmap indicate whether a subframe mapping to the each bit is an uplink subframe or a downlink subframe.
A base station that transmits control information in a wireless communication system, the base station comprising:

a process that configures DCI including TDD configuration indication information indicating information on a TDD UL/DL configuration to be changed;

a transmitting unit that transmits system information including the information on the TDD UL/DL configuration to a user equipment and transmits DCI including the TDD configuration indication information to the user equipment through a PDCCH; and

a receiving unit that receives data from the user equipment based on the TDD UL/DL configuration changed based on the TDD configuration indication information;

wherein the TDD configuration indication information is comprised of bitmap, and wherein each bit of the bitmap indicate whether a subframe mapping to the each bit is an uplink subframe or a downlink subframe.