WO2012134115A2 - Communication method and communication apparatus using an mbsfn subframe in a tdd-based wireless communication system - Google Patents

Abstract

Provided are a communication method and a communication apparatus using a multimedia broadcast single frequency network (MBSFN) subframe in a time division duplex (TDD)-based wireless communication system. The method comprises the following steps: receiving uplink-downlink (UL-DL) configuration information on a TDD wireless frame; receiving MBSFN configuration information; receiving an uplink grant for scheduling a second subframe in the first subframe; configuring the second subframe as an uplink subframe based on the MBSFN configuration information and uplink grant; and transmitting uplink data in the second subframe based on the uplink grant. The first subframe is any one of downlink subframes configured on the basis of the UL-DL configuration information, and the second subframe is any one of MBSFN subframes configured on the basis of the MBSFN configuration information.

Description

Communication method and apparatus using MBSFN subframe in TD based wireless communication system

The present invention relates to wireless communication, and more particularly, to a communication method and apparatus using a multimedia broadcast single frequency network (MBSFN) subframe in a time division duplex (TDD) based wireless communication system.

Long term evolution (LTE), based on the 3rd Generation Partnership Project (3GPP) Technical Specification (TS) Release 8, is a leading next-generation mobile communication standard.

LTE includes a frequency division duplex (FDD) system and a time division duplex (TDD) system. The FDD system uses different frequency bands in downlink and uplink, and is a system capable of simultaneous downlink transmission and uplink transmission. In the TDD system, the downlink and the uplink use the same frequency band, and the downlink transmission and the uplink transmission are separated in the time domain.

In a TDD system, a base station informs UL-DL configuration (uplink-downlink configuration) of a TDD frame through an upper layer signal. However, such UL-DL configuration is difficult to change dynamically. Therefore, it is difficult to efficiently allocate resources when the transmission amount is dynamically changed in uplink transmission and downlink transmission.

In order to solve this problem, resource allocation using a multimedia broadcast single frequency network (MBSFN) subframe may be considered in a TDD system. The MBSFN subframe is for a multimedia broadcast multicast service (MBMS). MBMS is a service that transmits the same signal simultaneously in several cells of a wireless communication system. Since the signal for MBMS is transmitted in multiple cells at the same time, unicast and reference signals are transmitted in different cells. Have different features and different frame structures.

There is a need for a communication method and apparatus capable of responding to dynamic change of uplink or downlink using an MBSFN subframe in a TDD system.

An object of the present invention is to provide a communication method and apparatus using an MBSFN subframe in a time division duplex (TDD) based wireless communication system.

In one aspect, a communication method using an MBSFN subframe in a TDD-based wireless communication system is provided. The method includes receiving uplink-downlink (UL-DL) configuration information for a TDD radio frame; Receiving MBSFN configuration information; Receiving an uplink grant scheduling a second subframe in a first subframe; Setting the second subframe as an uplink subframe based on the MBSFN configuration information and the uplink grant; And transmitting uplink data based on the uplink grant in the second subframe, wherein the first subframe is any one of downlink subframes configured by the UL-DL configuration information. The second subframe may be any one of MBSFN subframes set by the MBSFN configuration information.

The second subframe may include a PDCCH region to which a physical downlink control channel (PDCCH) is allocated, a switching time for switching between downlink reception and uplink transmission, and a region to which a physical uplink shared channel (PUSCH) is allocated.

The second subframe may include a plurality of orthogonal frequency division multiplexing (OFDM) symbols, and the PDCCH region may include first two OFDM symbols among the plurality of OFDM symbols.

The MBSFN configuration information may include a bitmap indicating a MBSFN subframe.

A bitmap indicating the MBSFN subframe may be housed for four consecutive TDD radio frames or given for one TDD radio frame.

When a bitmap indicating the MBSFN subframe is given for four consecutive TDD radio frames, each of the bits constituting the bitmap includes subframes # 3, # 4, # 7, in each TDD radio frame. It is shown whether # 8 and # 9 are MBSFN subframes, and the leftmost bit corresponds to subframe # 3 of the first TDD radio frame.

The MBSFN configuration information may be received through a system information block (SIB).

The uplink data may be transmitted through a physical uplink shared control channel (PUSCH).

The method further includes receiving a downlink grant and a physical downlink shared channel (PDSCH) for scheduling the third subframe in a third subframe, wherein the third subframe is an MBSFN configured by the MBSFN configuration information. One of the subframes may be a subframe configured as a downlink subframe by the downlink grant.

In another aspect, a terminal includes a radio frequency (RF) unit for transmitting and receiving a radio signal; And a processor connected to the RF unit, the processor receiving UL-DL configuration information for a TDD radio frame, receiving MBSFN configuration information, and receiving a second subframe in a first subframe. Receiving an uplink grant scheduling a subframe, setting the second subframe to an uplink subframe based on the MBSFN configuration information and the uplink grant, and based on the uplink grant in the second subframe Uplink data, wherein the first subframe is any one of downlink subframes configured by the UL-DL configuration information, and the second subframe is MBSFN subframes configured by the MBSFN configuration information. It is characterized in that any one of.

In a time division duplex (TDD) system, each subframe configuration state in a TDD frame may be dynamically changed according to an uplink or downlink transmission amount, a channel state, and the like. Thus, system performance is improved.

1 shows a structure of a radio frame.

2 shows a structure of a TDD radio frame.

3 shows an example of a resource grid for one downlink slot.

4 shows a downlink subframe structure.

5 shows a structure of an uplink subframe.

6 shows the structure of an MBSFN subframe.

7 illustrates a method of operating a terminal in a TDD system according to an embodiment of the present invention.

8 illustrates a method of operating a terminal in a TDD system according to another embodiment of the present invention.

9 shows an example of configuring an MBSFN subframe by MBSFN configuration information.

10 shows another example of configuring an MBSFN subframe in MBSFN configuration information.

11 is a block diagram illustrating a wireless device in which an embodiment of the present invention is implemented.

The user equipment (UE) may be fixed or mobile, and may include a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, and a personal digital assistant (PDA). It may be called other terms such as digital assistant, wireless modem, handheld device.

A base station generally refers to a fixed station communicating with a terminal, and may be referred to as other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), and an access point.

The communication from the base station to the terminal is called downlink (DL), and the communication from the terminal to the base station is called uplink (UL). The wireless communication system including the base station and the terminal may be a time division duplex (TDD) system or a frequency division duplex (FDD) system. The TDD system is a wireless communication system that performs uplink and downlink transmission and reception using different times in the same frequency band. The FDD system is a wireless communication system capable of transmitting and receiving uplink and downlink simultaneously using different frequency bands. The wireless communication system can perform communication using a radio frame.

1 shows a structure of a radio frame.

A radio frame includes 10 subframes, and one subframe includes two consecutive slots. Slots included in the radio frame are indexed from 0 to 19. The time taken for one subframe to be transmitted is called a transmission time interval (TTI), and the TTI may be a minimum scheduling unit. For example, one subframe may have a length of 1 ms, and one slot may have a length of 0.5 ms. A radio frame may also be referred to simply as a frame.

2 shows a structure of a TDD radio frame.

Referring to FIG. 2, a subframe having an index # 1 and an index # 6 is called a special subframe, and includes a downlink pilot time slot (DwPTS), a guard period (GP), and an uplink pilot time slot (UPPTS). ). DwPTS is used for initial cell search, synchronization or channel estimation at the terminal. UpPTS is used for channel estimation at the base station and synchronization of uplink transmission of the terminal. GP is a section for removing interference caused in the uplink due to the multipath delay of the downlink signal between the uplink and the downlink.

In TDD, a downlink (DL) subframe and an uplink (UL) subframe coexist in one radio frame. Table 1 shows an example of a UL-DL configuration of a radio frame.

TABLE 1

In Table 1, 'D' represents a DL subframe, 'U' represents a UL subframe, and 'S' represents a special subframe. Upon receiving the UL-DL configuration from the base station, the terminal may know whether each subframe is a DL subframe or a UL subframe in a radio frame. Hereinafter, the UL-DL configuration N (N is any one of 0 to 6) may refer to Table 1 above.

3 shows an example of a resource grid for one downlink slot.

Referring to FIG. 3, the downlink slot includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols in the time domain and N _RB resource blocks (RBs) in the frequency domain. The RB includes one slot in the time domain and a plurality of consecutive subcarriers in the frequency domain in resource allocation units. The number N _RB of resource blocks included in the downlink slot depends on the downlink transmission bandwidth N ^DL configured in the cell. For example, in the LTE system, N _RB may be any one of 6 to 110. The structure of the uplink slot may also be the same as that of the downlink slot.

Each element on the resource grid is called a resource element (RE). Resource elements on the resource grid may be identified by an index pair (k, l) in the slot. Where k (k = 0, ..., N _RB × 12-1) is the subcarrier index in the frequency domain, and l (l = 0, ..., 6) is the OFDM symbol index in the time domain.

In FIG. 3, one resource block includes 7 OFDM symbols in the time domain and 12 subcarriers in the frequency domain to include 7 × 12 resource elements, but the number of OFDM symbols and the number of subcarriers in the resource block is exemplarily described. It is not limited to this. The number of OFDM symbols and the number of subcarriers can be variously changed according to the length of the CP, frequency spacing, and the like. The number of subcarriers in one OFDM symbol may be selected and used among 128, 256, 512, 1024, 1536 and 2048.

4 shows a downlink subframe structure.

Referring to FIG. 4, a downlink (DL) subframe is divided into a control region and a data region in the time domain. The control region includes up to three OFDM symbols (up to four in some cases) of the first slot in the subframe, but the number of OFDM symbols included in the control region may be changed. A physical downlink control channel (PDCCH) and another control channel are allocated to the control region, and a physical downlink shared channel (PDSCH) is allocated to the data region.

As disclosed in 3GPP TS 36.211 V8.7.0, in 3GPP LTE, a physical channel is a physical downlink shared channel (PDSCH), a physical downlink shared channel (PUSCH), a physical downlink control channel (PDCCH), and a physical channel (PCFICH). It may be divided into a Control Format Indicator Channel (PHICH), a Physical Hybrid-ARQ Indicator Channel (PHICH), and a Physical Uplink Control Channel (PUCCH).

The PCFICH transmitted in the first OFDM symbol of a subframe carries a control format indicator (CFI) regarding the number of OFDM symbols (that is, the size of the control region) used for transmission of control channels in the subframe. The terminal first receives the CFI on the PCFICH, and then monitors the PDCCH. Unlike the PDCCH, the PCFICH does not use blind decoding and is transmitted on a fixed PCFICH resource of a subframe.

The PHICH carries a positive-acknowledgement (ACK) / negative-acknowledgement (NACK) signal for an uplink hybrid automatic repeat request (HARQ). The ACK / NACK signal for UL (uplink) data on the PUSCH transmitted by the UE is transmitted on the PHICH.

The Physical Broadcast Channel (PBCH) is transmitted in the preceding four OFDM symbols of the second slot of the first subframe of the radio frame. The PBCH carries system information necessary for the terminal to communicate with the base station, and the system information transmitted through the PBCH is called a master information block (MIB). In comparison, system information transmitted on the PDSCH indicated by the PDCCH is called a system information block (SIB). SIBs include SIB-1 to SIB-8. SIB-1 includes information on time domain scheduling of another SIB and parameters related to cell selection, and SIB-2 includes information on a common channel or a shared channel. For example, SIB-2 may include MBSFN configuration information. SIB-X (where X is a value from 3 to 8 or 9 or more) may be further set according to the release of the system.

Control information transmitted through the PDCCH is called downlink control information (DCI). DCI is a resource allocation of PDSCH (also called DL grant), a PUSCH resource allocation (also called UL grant), a set of transmit power control commands for individual UEs in any UE group. And / or activation of Voice over Internet Protocol (VoIP).

5 shows a structure of an uplink subframe.

Referring to FIG. 5, the uplink subframe is allocated a control region in which a physical uplink control channel (PUCCH) carrying uplink control information is allocated in a frequency domain and a physical uplink shared channel (PUSCH) carrying user data. It can be divided into data areas.

PUCCH is allocated to an RB pair in a subframe. RBs belonging to the RB pair occupy different subcarriers in each of the first slot and the second slot. RB pairs have the same resource block index m.

According to 3GPP TS 36.211 V8.7.0, PUCCH supports multiple formats. A PUCCH having a different number of bits per subframe may be used according to a modulation scheme dependent on the PUCCH format.

Table 2 below shows an example of a modulation scheme and the number of bits per subframe according to the PUCCH format.

TABLE 2

PUCCH format 1 is used for transmission of SR (Scheduling Request), PUCCH format 1a / 1b is used for transmission of ACK / NACK signal for HARQ, PUCCH format 2 is used for transmission of CQI, PUCCH format 2a / 2b is used for CQI and Used for simultaneous transmission of ACK / NACK signals. PUCCH format 1a / 1b is used when transmitting only the ACK / NACK signal in the subframe, and PUCCH format 1 is used when the SR is transmitted alone. When transmitting SR and ACK / NACK at the same time, PUCCH format 1 is used, and an ACK / NACK signal is modulated and transmitted on a resource allocated to the SR.

The present invention will now be described.

In the LTE Rel8 / 9/10 (hereinafter LTE) TDD system, after the base station configures the UL-DL, the base station cannot change the UL-DL configuration dynamically. Therefore, efficient resource utilization is difficult when the data rate required in the uplink or downlink of the system is dynamically changed. For example, in a situation where a large data rate is required in downlink, it is necessary to use a UL-DL configuration in which more downlink subframes are included in a TDD frame, such as UL-DL configuration 5. In a situation where a large data rate is required in the uplink, it is necessary to use a UL-DL configuration in which more uplink subframes are included in a TDD frame such as a UL-DL configuration 0. However, in the existing LTE, since the UL-DL configuration cannot be changed dynamically, resource utilization is low.

To solve this problem, a method of dynamically changing the UL-DL configuration may be considered. However, if the UL-DL configuration is dynamically changed, there is a problem in that the terminal operating by the existing LTE cannot recognize such a change.

In order to solve this problem, there is a method of dynamically setting a specific subframe in a TDD frame as a UL subframe or a DL subframe. According to this method, if the scheduling information for scheduling the subframe set to the DL subframe by the UL-DL configuration is determined to be an uplink grant, the UE uses the DL subframe as a UL subframe. If the UE has not received the uplink grant in advance, the UE determines the corresponding subframe as the DL subframe according to the UL-DL configuration and performs PDCCH decoding.

According to this method, a problem is that the UE may not recognize the DL subframe as a UL subframe. In this case, the UE recognizes the DL subframe as the DL subframe even though the corresponding DL subframe is changed to the UL subframe, and performs downlink measurement assuming a cell-specific reference signal (CRS). . Alternatively, downlink measurement is performed in a frequency band in which there is no PUSCH signal or no reference signal transmitted from another terminal. This wrong downlink measurement may result in radio link failure or the like.

Therefore, in the TDD system, some subframes of the TDD frame are dynamically changed and used according to an uplink or downlink situation, but a more reliable communication method is required. The present invention uses a multimedia broadcast single frequency network (MBSFN) subframe for this purpose. First, the MBSFN subframe will be described.

6 shows the structure of an MBSFN subframe.

Referring to FIG. 6, an MBSFN subframe is a subframe for transmitting a physical multicast channel (PMCH) and is a common reference signal (CRS) in a remaining region other than the PDCCH region consisting of the first two OFDM symbols. ) Means a subframe that may not be transmitted. Here, the CRS means a reference signal that can be recognized by all terminals in the cell. CRS is 3GPP TS 36.211. See section 6.10 of V9.1.0.

The UE that has not received reception in the MBSFN subframe does not perform downlink measurement on the remaining areas other than the PDCCH area.

That is, since the UE performs downlink measurement only in the PDCCH region in the MBSFN subframe, even if the remaining region is used for uplink transmission, there is an advantage that the downlink measurement does not have a significant effect. Therefore, the present invention considers a method of borrowing and using an MBSFN subframe as an UL subframe.

7 illustrates a method of operating a terminal in a TDD system according to an embodiment of the present invention.

Referring to FIG. 7, the base station transmits UL-DL configuration information to the terminal (S210). The UL-DL configuration may indicate any one of the UL-DL configurations shown in Table 1.

The base station transmits MBSFN configuration information (S220).

MBSFN configuration information is information for setting an MBSFN subframe. MBSFN configuration information may be transmitted through a higher layer signal. For example, the base station may transmit MBSFN configuration information through SIB-2 transmitted through the PDSCH. The MBSFN configuration information may include a bitmap indicating a MBSFN subframe, a radio frame allocation period (radioFrameAllocationPeriod), a radio frame allocation offset (radioFrameAllocationOffset), a subframe allocation (subframeAllocation), and the like.

The bitmap indicating the MBSFN subframe may be given in units of 4 frames or 1 frame. 1) When given in units of four frames, the bitmap may indicate the location of MBSFN subframes in four consecutive frames. If the value of the bit constituting the bitmap is '1', it indicates that the corresponding subframe is an MBSFN subframe. In FDD, a bitmap is composed of bit strings indicating whether subframes # 1, # 2, # 3, # 6, # 7, and # 8 of each frame are MBSFN subframes. Accordingly, the bitmap may consist of 24 bits for a total of four frames, and the first bit (ie, the leftmost bit) corresponds to subframe # 1 of the first frame, and in the same manner, in turn. In TDD, a bitmap consists of bit strings indicating whether subframes # 3, # 4, # 7, # 8, and # 9 of each frame are MBSFN subframes. Even in this case, the bitmap may consist of 24 bits in total, and the last 4 bits are not used. In TDD, subframes # 0, # 1, # 2, # 5, which are fixed with D (downlink subframe), S (special subframe), and U (uplink subframe) in common to all UL-DL configuration information. # 6 is restricted not to be allocated to MBSFN subframes.

2) When given in units of one frame, in FDD, a bitmap consisting of 6 bits indicates whether subframes # 1, # 2, # 3, # 6, # 7, and # 8 in one frame are MBSFN subframes. The first bit (ie, the leftmost bit) corresponds to subframe # 1, and the rest correspond in order. Also in TDD, a bitmap composed of 6 bits indicates whether subframes # 3, # 4, # 7, # 8, and # 9 in one frame are MBSFN subframes, and the first bit (that is, the leftmost bit) is subframe # Corresponds to 3 and the rest correspond in turn. At this time, the last bit is not used.

The radio frame allocation period and the radio frame allocation offset may indicate a frame including the MBSFN subframe. For example, a frame satisfying “system frame number (SFN) mod radio frame allocation period = radio frame allocation offset” may include an MBSFN subframe. mod stands for modular operation. Subframe allocation defines subframes allocated for MBSFN within a radio frame allocation period defined by a radio frame allocation period and a radio frame allocation offset.

The base station transmits an UL grant for scheduling the second subframe in the first subframe (S230). Here, the first subframe may be any one of DL subframes configured by the UL-DL configuration information. The second subframe may be any one of the MBSFN subframes set by the MBSFN configuration information.

When the UE receives the UL grant for scheduling the second subframe in the first subframe, it can be seen that the second subframe is used as the UL subframe despite the UL-DL configuration information. Therefore, the second subframe is set to the UL subframe.

The UE transmits the PUSCH in the second subframe (S250). The PUSCH may be transmitted based on the UL grant. Since the UE recognizes that the second subframe is an UL subframe, the UE may not attempt blind decoding on the PDCCH including the DL grant in the second subframe. This is because the DL grant and the PDSCH scheduled therefrom are located in the same subframe.

8 illustrates a method of operating a terminal in a TDD system according to another embodiment of the present invention.

Referring to FIG. 8, the base station transmits UL-DL configuration information to the terminal (S310). The UL-DL configuration may indicate any one of the UL-DL configurations shown in Table 1.

The base station transmits MBSFN configuration information (S320).

The base station transmits the DL grant and the PDSCH scheduling the third subframe in the third subframe (S330). Here, the third subframe may be any one of the MBSFN subframes set by the MBSFN configuration information.

When the DL grant is included in the PDCCH region of the third subframe, the terminal decodes the PDSCH in the third subframe based on the DL grant (S340).

When the MBSFN subframe is used as the DL subframe, the CRS or the DM RS (demodulation reference signal) may be transmitted not only in the PDCCH region but also in the rest of the MBSFN subframe. CRS and DM RS are described in 3GPP TS 36.211. See section 6.10 of V9.1.0.

9 shows an example of configuring an MBSFN subframe by MBSFN configuration information.

Referring to FIG. 9, in FDD, a bitmap includes a bit string indicating whether subframes # 1, # 2, # 3, # 6, # 7, and # 8 of each frame are MBSFN subframes. When the bitmap is '111111', subframes # 1, # 2, # 3, # 6, # 7, and # 8 in the FDD frame are set as MBSFN subframes.

In TDD, a bitmap is composed of bit strings indicating whether subframes # 3, # 4, # 7, # 8, and # 9 of each frame are MBSFN subframes. If the bitmap is '11111' (or '11111x', the last bit is not used, where x is 1 or 0) and subframes # 3, # 4, # 7, # 8 and # 9 is set to the MBSFN subframe. If a specific bit in the bitmap is '0', the corresponding subframe is not set to the MBSFN subframe but is used for the purpose of UL-DL configuration information.

10 shows another example of configuring an MBSFN subframe in MBSFN configuration information.

10 shows another example of configuring an MBSFN subframe in MBSFN configuration information.

Referring to FIG. 10, when the MBSFN subframe 801 is configured as a UL subframe through a bitmap of MBSFN configuration information, downlink / uplink is performed between the PDCCH region and the region transmitting the PUSCH in the MBSFN subframe 801. A switching time for link switching can be added. This switching time is sometimes called a gap.

The switching time may use some or all OFDM symbols in the PDCCH region and some OFDM symbols in the PDSCH region.

When a subframe configured as an MBSFN subframe is used as a UL subframe according to the present invention for UL transmission, the subframe may be used with the following characteristics.

The UL transmission may operate in a synchronous transmission method as in the conventional (non-MBSFN) UL subframe. That is, the HARQ process and the subframe index may operate in a manner connected. In this case, the UL grant for scheduling the PUSCH need not directly inform the HARQ process number and the like.

If the UL transmission in the MBSFN subframe allows only an asynchronous transmission scheme, the UL grant scheduling the PUSCH of the MBSFN subframe should be able to directly inform the HARQ process number, the redundancy version, and the like.

The PUSCH scheduled in the MBSFN subframe through the UL grant may not involve downlink ACK / NACK through PHICH. In other words, PDCCH-less retransmission is not allowed. This is because there is a problem that the subframe to be retransmitted becomes unclear when considering retransmission without PDCCH. In this case, the base station may use a scheme of directly transmitting the ACK / NACK through the UL grant without transmitting the downlink ACK / NACK through the PHICH.

For example, the base station may consider a method of implicitly delivering ACK / NACK by using a new data indicator (NDI) bit included in the UL grant. If the NDI bit is toggled, the terminal may transmit new data. If the NDI bit is not toggled, the terminal may recognize that the NACK has been transmitted with respect to the previously transmitted data and may retransmit the data.

In addition, the PDCCH including the UL grant scheduling the UL transmission in the MBSFN subframe may be limited to be transmitted only in the MBSFN subframe. In the prior art, since the non-MBSFN subframe cannot allocate the UL grant to the MBSFN subframe, the method of restricting the transfer of the UL grant to another MBSFN subframe only within the MBSFN subframe for compatibility with this prior art. May be considered.

Table 3 is a table illustrating a subframe (n-k ') in which a UL grant for scheduling a PUSCH transmission in MBSFN subframe n is transmitted when MBSFN subframe n is used as a UL subframe. That is, the values in Table 3 represent k 'values.

In Table 3, a column in which only numbers are indicated indicates that a UL subframe according to each UL-DL configuration. The shaded column represents a subframe that can be used as a UL subframe among MBSFN subframes. It should be noted that even in a subframe used as a UL subframe among the MBSFN subframes, since the PDCCH region exists, the UL grant may be received in such a subframe.

TABLE 3

Considering the communication process between the base station and the terminal, after the base station transmits the UL grant, the terminal receives the UL grant through a propagation delay. In addition, the terminal needs time to prepare for UL transmission. In consideration of these points, it can be seen that a UL grant for scheduling the UL transmission is transmitted in a DL subframe or an MBSFN subframe at least four subframes before the UL transmission.

In Table 4, a subframe in which a UL grant or a PHICH is transmitted is referred to as a subframe n. It is displayed.

TABLE 4

Referring to Table 4, in the other UL-DL configuration except for the UL-DL configuration 3, when the MBSFN subframe is borrowed as a UL subframe, UL grant transmission and reception on the PDCCH before the 4th subframe is possible.

However, for example, in the case of subframes 7 and 8 in the UL-DL configuration 3, transmission of the PDCCH including the UL grant is impossible because the subframe before the 4th subframe is configured as the UL subframe. Therefore, in this case, a UL grant for subframes 7,8 may be transmitted in subframe 1, which is the previous DL subframe closest to subframes 7,8.

When a plurality of UL subframes should be scheduled in one DL subframe, such as UL-DL configuration 0 and 3, a downlink assignment index (DAI) field included in a UL grant transmitted in the corresponding DL subframe is used as a UL index. Can be. Here, the UL index is indication information for identifying which UL subframe the UL grant is.

For example, the UL grant transmitted in subframe 1 of UL-DL configuration 3 of Table 4 may include subframe 7, if the value of the DAI field is binary '10', subframe 8, and DAI if the value of the DAI field is binary '01'. If the value of the field is binary 11, it may indicate that the subframes 7 and 8 are scheduled at the same time.

The UL index is subframes 0, 5 in UL-DL configuration 1, subframes 0, 4, 5, 9 in UL-DL configuration 2, subframes 1, 5 in UL-DL configuration 3, and subframes in UL-DL configuration 4 It may be applied to all of subframes 0, 3, 4, 5, and 9 in frames 0, 1, 4, 5, and UL-DL configuration 5. For example, in the UL-DL configuration 3, a DAI field of a UL grant transmitted in subframe 1 and subframe 5 may be used as a UL index. Since the UL subframe scheduled by the UL grant in the corresponding subframe is a subframe without an ACK / NACK response for the PDSCH, which is a DL data channel, the UL subframe should be transmitted in a fixed uplink such as subframes 2, 3, and 4. This is because the UL DAI field, which was used as the total number of ACK / NACK responses, does not need to be used.

If the UL index is configured as a separate field instead of the DAI field, the PUSCH transmitted after 7 subframes in the DL subframe or MBSFN subframe in which the UL grant is transmitted using the bitmap of the UL index as described above is used. You can also make additional scheduling. For example, in all UL-DL configurations, a UL grant transmitted in subframes 0, 1 or 5 may be configured to schedule PUSCHs transmitted in subframes 4, 7, 7, and 8, 9, and 2, respectively. Of the subframes configured as MBSFN subframes, subframes 8 and 9 do not need to transmit UL grants because the subframes after the 7th subframe are always DL subframes.

Meanwhile, in order not to use the UL index, only one of subframes 7 or 8 may be configured as an MBSFN subframe that can be borrowed as a UL subframe in the UL-DL configuration 3.

11 is a block diagram illustrating a wireless device in which an embodiment of the present invention is implemented.

The base station 100 includes a processor 110, a memory 120, and an RF unit 130. The processor 110 implements the proposed functions, processes and / or methods. For example, the processor 110 transmits uplink-downlink (UL-DL) configuration information for a TDD radio frame and transmits MBSFN configuration information. In addition, an uplink grant for scheduling the second subframe is transmitted from the first subframe within the TDD radio frame. Receives uplink data transmitted by the terminal based on the uplink grant in the second subframe. The memory 120 is connected to the processor 110 and stores various information for driving the processor 110. The RF unit 130 is connected to the processor 110 and transmits and / or receives a radio signal.

The terminal 200 includes a processor 210, a memory 220, and an RF unit 230. The processor 210 implements the proposed functions, processes and / or methods. For example, the processor 210 receives uplink-downlink (UL-DL) configuration information for a TDD radio frame, receives MBSFN configuration information, and schedules a second subframe in a first subframe. Receive a link grant. In addition, the second subframe is set as an uplink subframe based on the MBSFN configuration information and the uplink grant, and the uplink data is transmitted based on the uplink grant in the second subframe. Also, a DL grant and a PDSCH for scheduling a third subframe are received in the third subframe. This process has been described with reference to FIGS. 7 to 10. The memory 220 is connected to the processor 210 and stores various information for driving the processor 210. The RF unit 230 is connected to the processor 210 to transmit and / or receive a radio signal.

Processors 110 and 210 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, data processing devices, and / or converters for interconverting baseband signals and wireless signals. The memory 120, 220 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium, and / or other storage device. The RF unit 130 and 230 may include one or more antennas for transmitting and / or receiving a radio signal. When the embodiment is implemented in software, the above-described technique may be implemented as a module (process, function, etc.) for performing the above-described function. The module may be stored in the memories 120 and 220 and executed by the processors 110 and 210. The memories 120 and 220 may be inside or outside the processors 110 and 210, and may be connected to the processors 110 and 210 by various well-known means.

Although the present invention has been described above with reference to the embodiments, it will be apparent to those skilled in the art that the present invention may be modified and changed in various ways without departing from the spirit and scope of the present invention. I can understand. Therefore, the present invention is not limited to the above-described embodiment, and the present invention will include all embodiments within the scope of the following claims.

Claims (12)

A communication method using a multimedia broadcast single frequency network (MBSFN) subframe in a time division duplex (TDD) based wireless communication system,
Receiving uplink-downlink (UL-DL) configuration information for a TDD radio frame;
Receiving MBSFN configuration information;
Receiving an uplink grant scheduling a second subframe in a first subframe;
Setting the second subframe as an uplink subframe based on the MBSFN configuration information and the uplink grant; And
Transmitting uplink data based on the uplink grant in the second subframe,
The first subframe is any one of downlink subframes configured by the UL-DL configuration information, and the second subframe is any one of MBSFN subframes configured by the MBSFN configuration information. Way. The method of claim 1, wherein the second subframe
A PDCCH region to which a physical downlink control channel (PDCCH) is allocated, a switching time for switching between downlink reception and uplink transmission, and a region to which a physical uplink shared channel (PUSCH) is allocated. The method of claim 2,
And wherein the second subframe includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols, and wherein the PDCCH region consists of the first two OFDM symbols of the plurality of OFDM symbols. The method of claim 1, wherein the UL-DL configuration information is
Method of indicating any one of the UL-DL configuration shown in the following table.

The method of claim 1, wherein the MBSFN configuration information comprises a bitmap indicating a MBSFN subframe. 6. The method of claim 5, wherein a bitmap indicating the MBSFN subframe is housed for four consecutive TDD radio frames or is given for one TDD radio frame. 7. The method of claim 6, wherein when a bitmap indicating the MBSFN subframe is given for four consecutive TDD radio frames, each bit constituting the bitmap includes subframe # 3 in each TDD radio frame. # 4, # 7, # 8, # 9 indicates whether the MBSFN subframe is the leftmost bit, and the leftmost bit corresponds to subframe # 3 of the first TDD radio frame. The method of claim 1, wherein the MBSFN configuration information is received through a system information block (SIB). The method of claim 1, wherein the uplink data is transmitted through a physical uplink shared control channel (PUSCH). 10. The method of claim 9, wherein the second subframe is referred to as subframe n, and a subframe that receives an uplink grant for scheduling a physical uplink shared control channel (PUSCH) transmission in the subframe n is referred to as subframe nk. When k is given as in the following table.

The method of claim 1, further comprising receiving a downlink grant and a physical downlink shared channel (PDSCH) for scheduling the third subframe in a third subframe,
And the third subframe is one of MBSFN subframes set by the MBSFN configuration information, and is a subframe set as a downlink subframe by the downlink grant. A radio frequency (RF) unit for transmitting and receiving a radio signal; And
Including a processor connected to the RF unit,
The processor receives uplink-downlink (UL-DL) configuration information for a TDD radio frame, receives MBSFN configuration information, receives an uplink grant scheduling a second subframe in a first subframe, Set the second subframe as an uplink subframe based on the MBSFN configuration information and the uplink grant, and transmit uplink data based on the uplink grant in the second subframe,
The first subframe is any one of downlink subframes configured by the UL-DL configuration information, and the second subframe is any one of MBSFN subframes configured by the MBSFN configuration information. Terminal.

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