KR20170106268A - Apparatus and method for transmitting and receiving data - Google Patents

Abstract

The present invention relates to an apparatus and a method to transmit/receive data, capable of allowing a general subframe to select an effective transmission mode between an existing long term evolution (LTE) transmission mode and a transmission mode newly introduced to an advanced long term evolution (LTE-A), to apply the selected mode to an LTE-A user, and capable of allowing a multicast broadcast single frequency network (MBSFN) subframe to additionally select a different transmission mode to apply the selected mode to the LTE-A user. According to the present invention, the method comprises: a step of receiving information about at least one transmission mode among a plurality of transmission modes; a step of receiving information about the MBSFN subframe; a step of receiving downlink control information (DCI) about a data signal; and a step of determining at least one transmission mode corresponding to the current subframe based on the information about the at least one transmission mode, the information about the MBSFN subframe, and a format of the DCI; and a step of processing the data signal based on the transmission mode.

Description

[0001] APPARATUS AND METHOD FOR TRANSMITTING AND RECEIVING DATA [0002]

The invention relates to a method for setting a data transmission and reception method and apparatus in the ^{3GPP (3 rd Generation Partnership Project)} LTE (Long Term Evolution) system and the LTE-A (LTE Advance) system evolved his system.

The mobile communication system has evolved into a high-speed and high-quality wireless packet data communication system for providing data service and multimedia service apart from providing initial voice-oriented service. Various mobile communication standards such as High Speed Packet Access (HSPA) of 3GPP, LTE, High Rate Packet Data (HRPD) of 3GPP2, UMB (Ultra Mobile Braodband) and IEEE 802.16e support high speed and high quality wireless packet data transmission service .

In order to improve the transmission efficiency, the latest mobile communication system employs techniques such as an Adaptive Modulation and Coding (AMC) method and a channel responsive scheduling method. With the AMC method, the transmitter can adjust the amount of data to be transmitted according to the channel state. In other words, if the channel state is poor, the amount of data transmitted from the transmitter is reduced to set the reception error probability to a desired level. If the channel state is good, the amount of data transmitted from the transmitter is increased, Can be effectively transmitted. Using the above-described channel-responsive scheduling method, the transmitter selectively provides service to a receiver having a good channel state among a plurality of receivers. Therefore, the system capacity increases as compared with a case where a channel is allocated and serviced in one receiver.

In other words, the AMC method and the channel-responsive scheduling method are based on feedback of partial channel state information (CSI) from a receiver and apply an appropriate modulation and coding scheme to a time point determined to be the most efficient. The AMC method and the channel responsive scheduling method are techniques for improving transmission efficiency in a state where a transmitter has acquired sufficient information about a transmission channel. The receiver is designed to report information about the transmission channel to the transmitter when the transmitter can not infer the state of the transmission channel through the reception channel, as in the FDD (Frequency Division Duplex) scheme. On the other hand, in the TDD (Frequency Division Duplex) scheme, a receiver can omit reporting information on a transmission channel to a transmitter by utilizing a characteristic of knowing the state of the transmission channel through the reception channel.

Recently, studies have been actively conducted to convert Code Division Multiple Access (CDMA), which is a multiple access scheme used in the second and third generation mobile communication systems, into OFDMA (Orthogonal Frequency Division Multiple Access) in the next generation system. Standard organizations such as 3GPP, 3GPP2, and IEEE are in the process of standardizing on evolutionary systems using OFDMA or modified OFDMA. This is because the capacity increase can be expected in the OFDMA system as compared with the CDMA system. One of the various causes of capacity increase in the OFDMA scheme is that frequency domain scheduling can be performed on the frequency axis. As the channel gains the capacity gain by the channel adaptive scheduling method according to the time varying characteristic, the channel gain can be obtained by utilizing the characteristic that varies according to the frequency.

In the LTE system, an OFDMA scheme is adopted in a downlink (DL), and a single-carrier frequency division multiple access (SC-FDMA) scheme is used in an uplink It has a feature that can perform scheduling.

On the other hand, the DL of the LTE system supports multi-antenna transmission. The transmitter of the LTE system may have one, two, or four transmission antennas. When a plurality of transmission antennas are provided, precoding is applied to obtain a beam forming gain and a spatial multiplexing gain. Can be obtained. In the LTE system, the receiver transmits a common reference signal (CRS) for each transmit antenna to estimate the channel response from each transmit antenna. When adaptive pre-coding is applied to data transmission, the transmitter notifies the receiver of what pre-coding has been applied through the control channel.

The DL of the LTE-A system supports up to 8 transmit antennas by increasing the number of transmit antennas of the transmitter. As the number of transmit antennas increases, the transmitter can further improve the beamforming gain and spatial multiplexing gain. However, to support up to 8 transmit antennas, the amount of CRS to estimate the channel state from each transmit antenna increases. In the LTE-A system, the CSI-RS, which is used for generating the CSI feedback information, and the Demodulation (DM-RS), which is used for data demodulation, is used in order to prevent the proportion of the CRS from increasing rapidly as the number of transmission antennas increases. -RS). Newly introduced transmission schemes in LTE-A systems use CSI-RS and DM-RS, but in order to maintain backward compatibility, LTE-A transmitters must also transmit CRS.

Meanwhile, the LTE-A system supports Multimedia Broadcast Multicast Service Single Frequency Network (MBSFN) transmission. MBSFN transmission is a transmission scheme that broadens the service area of broadcasting by transmitting the same broadcast signal in multiple cells. The MBSFN transmission is required to transmit the same RS in multiple cells in order to allow a receiver to perform coherent demodulation without distinguishing cells transmitted simultaneously from multiple cells. That is, since the CRS defined for each cell can not support MBSFN, only the MBSFN dedicated RS is defined and transmitted in the MBSFN subframe. And since the MBSFN subframe does not support unicast service, CRS is not transmitted.

The LTE system defines a plurality of transmission modes so that an appropriate transmission scheme can be selected according to the state of the receiver. In the LTE system, channel estimation for demodulation defines a transmission scheme using CRS and a transmission scheme using DRS (Dedicated Reference Signal). Meanwhile, the LTE-A system adds a transmission scheme using DM-RS as a channel estimation for demodulation. For backward compatibility, the receiver of the LTE-A system must be able to receive both CRS, DRS, and DM-RS.

The receiver of the LTE-A system can also receive the unicast service in the MBSFN subframe. This is because the CRS is not transmitted in the MBSFN sub-frame, but the DM-RS can transmit the MBSFN sub-frame as a resource with no subsequent interchangeability. In the present invention, a subframe configured to support unicast service in an MBSFN subframe is referred to as an LTE-A subframe for convenience, in order to distinguish it from an MBSFN subframe configured to support the MBSFN service.

In the above-described LTE-A system, the operation of the receiver of the LTE-A system for receiving the unicast service in the MBSFN subframe should be defined. A receiver of the LTE-A system can receive data in a normal subframe when it is set to a transmission mode using CRS for demodulation. However, since the CRS is not transmitted in the MBSFN subframe, the receiver of the LTE- Data can not be received even though reception is possible.

According to another aspect of the present invention, there is provided a data reception method including the steps of confirming a transmission mode set corresponding to a current subframe, and receiving a data signal by estimating a channel according to the transmission mode . At this time, in the data reception method according to the present invention, the transmission mode includes at least one of a transmission mode for a normal subframe or a transmission mode for an LTE-A subframe. In the data receiving method according to the present invention, the receiving step receives the data signal according to a transmission mode for the LTE-A subframe if the current subframe is an LTE-A subframe, If the frame is a normal sub-frame, the data signal is received according to a transmission mode for the normal sub-frame.

According to another aspect of the present invention, there is provided a data transmission method including determining a transmission mode for a terminal and notifying the terminal of the transmission mode, and transmitting a data signal and a reference signal for the terminal . At this time, in the data transmission method according to the present invention, the transmission mode includes at least one of a transmission mode for a general subframe or a transmission mode for an LTE-A subframe.

According to another aspect of the present invention, there is provided a data reception apparatus comprising: a reception controller for confirming a transmission mode set corresponding to a current subframe; A channel estimator and a data processor for receiving and processing the data signal in the channel under the control of the reception controller. At this time, in the data reception apparatus according to the present invention, the transmission mode includes at least one of a transmission mode for a general subframe or a transmission mode for an LTE-A subframe. In the data receiving apparatus according to the present invention, if the current subframe is an LTE-A subframe, the reception controller receives the data signal according to a transmission mode for the LTE-A subframe, If the frame is a normal sub-frame, the data signal is received according to a transmission mode for the normal sub-frame.

In addition, a data transmitting apparatus according to the present invention for solving the above-mentioned problems includes a transmission controller for determining a transmission mode for a terminal and notifying the terminal of the transmission mode, and a transmission controller for multiplexing a data signal and a reference signal for the terminal And a multiplexer. At this time, in the data transmission apparatus according to the present invention, the transmission mode includes at least one of a transmission mode for a normal subframe or a transmission mode for an LTE-A subframe.

An object of the present invention is to provide a transmission technology control method for supporting a CRS-based existing transmission scheme in a general subframe even in a receiver of an LTE-A system, and to provide a receiver of an LTE-A system configured to use a CRS- So that data can be received in the LTE-A subframe. That is, the present invention helps improve the capacity of the system and improve the data rate at the receiver of the LTE-A system.

1 is a diagram illustrating a downlink transmission apparatus using a CRS of a transmitter in an LTE system,
2 is a diagram illustrating a downlink transmission apparatus using a DRS of a transmitter in an LTE system,
3 is a diagram showing an example of downlink resource mapping in an LTE system,
4 is a diagram for explaining time division multiplexing of MBSFN subframes,
5 is a view for explaining time division multiplexing of an LTE-A subframe,
6 is a diagram illustrating a transmitter structure according to an embodiment of the present invention;
7 is a diagram illustrating a structure of a receiver according to an embodiment of the present invention;
8 is a diagram illustrating a reference signal using procedure of a receiver according to the first, third, and fourth embodiments of the present invention;
9 is a diagram illustrating a reference signal using procedure of a receiver according to a second embodiment of the present invention, and
10 is a diagram illustrating a reference signal using procedure of a receiver according to a fifth embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same components are denoted by the same reference symbols as possible in the accompanying drawings. Further, the detailed description of known functions and configurations that may obscure the gist of the present invention will be omitted.

A reference signal (RS) is a signal set for the transmitter and receiver for two purposes. The first purpose is to measure the CSI for the transmitter to the receiver, ie, to support AMC, the transmitter The receiver should be able to measure the CSI through the RS and the second purpose is to estimate the channel response for demodulating the signal received at the receiver For example, The receiver must be able to estimate how the transmitted signal is distorted on the channel for coherent demodulation when the transmitter transmits a complex signal, that is, upon receipt of the RS, Can be estimated.

The LTE system defines an RS that is commonly used by all receivers in a cell in a DL. This RS is called a common RS (hereinafter referred to as "CRS ") and is also referred to as a cell-specific RS by being defined differently for each cell. When a transmitter transmits a signal through multiple transmit antennas, the CRS is designed to be orthogonal for each transmit antenna. For example, if there are two transmit antennas, the transmitter defines two orthogonal CRSs and transmits through each transmit antenna.

1 shows a downlink transmission apparatus using a CRS of a transmitter in an LTE system. In this case, it is assumed that the transmitter has two transmit antennas, but the present invention is not limited to this. That is, the same applies even if the transmitter has more than two transmit antennas.

1, a transmitter 100 includes a pre-encoder 103, a first multiplexer 109a, a second multiplexer 109b, a first transmit antenna 111a, and a second transmit antenna 111b do. At this time, the transmitter 100 multiplexes the data signal 101 together with the common reference signals 107a and 107b and transmits it.

Upon input of a data signal 101 for a receiver (not shown), the precoder 103 beamforms the data signal 101. [ Here, the data signal 101 is composed of one or a plurality of layers. When the data signal 101 is composed of one layer, pre-coding corresponds to general beam forming. Or the data signal 101 is composed of a plurality of layers, the pre-coding is beamformed for each layer of the data signal 101 for spatial multiplexing. The pre-encoded signal 105 is passed along the processing path to the first multiplexer 109a and the second multiplexer 109b. The first multiplexer 109a multiplexes the pre-coded signal 105 and the first CRS 107a at the time of inputting the pre-coded signal 105 and the first CRS 107a, Lt; / RTI > The second multiplexer 109b multiplexes the pre-coded signal 105 and the second CRS 107b and transmits the pre-coded signal 105 and the second CRS 107b to the second transmission antenna 111b, Lt; / RTI >

At this time, in the DL transmission using the CRS 107a and 107b, the data signal 101 is pre-encoded while the CRS 107a and 107b are not pre-encoded. Through these CRSs 107a and 107b, the receiver can measure the CSI in which the pre-coding is not reflected. The receiver reports the CSI directly to the transmitter 100 or reports to the transmitter 100 the most preferred transmission scheme in a given channel condition.

The feedback information reported to the transmitter in the LTE system is defined as a preferred transmission scheme. The channel quality indicator (CQI), the precoding matrix indicator (PMI), the rank indicator (RI) Etc. are feedback information defined to support DL transmission in an LTE system. CQI, PMI, and RI represent the modulation and coding scheme, the most preferred pre-coding scheme, and the number of spatial multiplexing layers that can be received, respectively, which can be received in a given channel condition.

However, when reporting CQI, PMI, and RI, the pre-coding method is limited because the receiver uses only the pre-coding scheme defined in the precoding codebook introduced in the standard. For example, the receiver selects one of the pre-coding matrices defined in the pre-coding codebook and reports it to the transmitter, and the transmitter selects the pre-coding scheme from the pre-coding codebook based on the information, and applies it to the actual transmission. Therefore, the transmitter can not apply pre-coding not defined in the pre-coding codebook. For this reason, in the LTE system, downlink control information (hereinafter referred to as "DCI") includes information on the pre-coding scheme actually used in the data signal.

On the other hand, in the LTE-A system, the transmitter is allowed to apply pre-coding that is not defined in the pre-coding codebook. An advantage of this scheme is that the transmitter can arbitrarily determine the pre-coding scheme. As a result, the CRS-based transmission scheme can not be used as it is. That is, since the number of pre-coding schemes is infinite, the pre-coding scheme can not be announced using DCI. Accordingly, only one layer transmission in the LTE system adopts a reference signal for each receiver, that is, a dedicated RS (DRS), and DRS uses the same pre-coding scheme as the data signal. Therefore, the receiver can demodulate the pre-coded data signal by estimating the pre-coded channel through the DRS without informing the pre-coding method actually applied using the DCI. In LTE system, DM-RS is introduced in release-9, and this transmission is expanded to two-layer transmission. In LTE-A system, up to 8 DM-RS are defined to support up to 8 layer transmission. The DM-RS also uses the same pre-coding scheme as the data signal. Even if the pre-coding scheme actually applied using the DCI is not indicated, the receiver estimates the pre-coded channel through the DM-RS and demodulates the pre-coded data signal .

2 shows a downlink transmission apparatus using a DRS of a transmitter in an LTE system. In this case, it is assumed that the transmitter has two transmit antennas, but the present invention is not limited to this. That is, the same applies even if the transmitter has more than two transmit antennas. In addition, although the use of DRS is limited to one layer transmission in the LTE system, the DRS concept can be applied to spatial multiplexing in which up to eight layers are configured and transmitted in the LTE-A system.

2, the transmitter 120 includes a multiplexer 125, a pre-encoder 127, a first transmission antenna 131a, and a second transmission antenna 131b. At this time, the transmitter 120 multiplexes and pre-encodes the data signal 121 together with the DRS 123 and transmits it.

Upon input of the data signal 121 and the DRS 123 for a receiver (not shown), the multiplexer 125 multiplexes the data signal 121 and the DRS 123 and transfers the data signal 121 and the DRS 123 to the pre- The pre-encoder 127 generates the pre-coded signal 129 and transmits it through the first transmission antenna 131a and the second transmission antenna 131b. The pre-encoded signal 129 includes a data signal 121 and a DRS 123. The receiver estimates the channel of the data signal 121 to the DRS 123 and outputs the pre- Can be estimated based on the pre-coded channel response.

3 shows an example of downlink resource mapping in the LTE system. Here, it is assumed that the DL resource is implemented according to a normal CP (normal cyclic prefix) subframe structure, but the present invention is not limited thereto. That is, the DL resource may be implemented according to an extended CP (CP) subframe structure.

Referring to FIG. 3, the minimum resource unit on the time axis is an OFDM symbol (201). One slot 203 is composed of seven OFDM symbols 201 and one subframe 205 is composed of two slots 203. This subframe 205 is a basic unit of resource allocation on the time axis. One, two, or three OFDM symbols 201 at the head in one subframe 205 are used as a control channel region, and the remaining OFDM symbols 201 are used as a data channel region. And the minimum resource unit on the frequency axis is a subcarrier 207. [ One resource block (RB) 211 is composed of 12 subcarriers. The RB 211 is a basic unit of resource allocation on the frequency axis. Accordingly, one subcarrier 207 on the frequency axis, one OFDM symbol 201 on the time axis, and one antenna port (not shown) on the spatial axis form a resource element, which is the smallest unit of resources. RE) 209, and one modulation symbol is transmitted and received to the RE 209. [

For example, if the transmitter has four transmit antennas, that is, four antenna ports, the transmitter defines and transmits a CRS (220. 221, 222, 223) for each antenna port. In order for the receiver to be able to estimate the channels of antenna ports 0, 1, 2 and 3, the transmitter must have CRS0 220 for antenna port 0, CRS1 221 for antenna port 1, CRS2 222 and the CRS 3 223 for the antenna port 3. At this time, the transmitter transmits the CRS0 220, the CRS1 221, the CRS2 222, and the CRS3 223 to the different REs 209, respectively. Accordingly, the CRS0 220, the CRS1 221, the CRS2 222, and the CRS3 223 are orthogonal to each other. In addition, the transmitter transmits the control channel signal 225 of the data signal to the RE 209 of the control channel region and the data channel signal 227 of the data signal to the RE 209 of the data channel region. In order to define the positions of the CRSs 220, 221, 222 and 223 differently for each cell, an offset 213 for each cell is determined differently according to the cell identification.

In this LTE system, the transmitter can transmit a data signal and a reference signal according to a transmission mode (hereinafter referred to as "TM") as shown in Table 1 below. Table 1 below is a table listing transmission modes available in the DL of the LTE system. Two data transmission schemes are supported for each transmission mode. The reference transmission scheme is a transmission scheme allowed only in the corresponding transmission mode, and the alternative transmission scheme is a transmission scheme commonly allowed in all transmission modes.

Although the LTE system supports various reference transmission methods, it is not possible to freely select all the reference transmission methods at each transmission time. Each reference transmission scheme requires a different DCI, and the receiver must know in advance which DCI to receive. Therefore, if the transmitter sets a specific common transmission mode to one receiver, the receiver performs the reception operation in the reference transmission mode of the common transmission mode. In this case, since the setting of the common transmission mode is performed through higher layer signaling, a time delay can not be avoided in the setting process. If the reference transmission scheme of the common transmission mode set in the specific receiver is changed to a channel state that is no longer valid, an alternative transmission scheme for changing the common transmission mode of the corresponding receiver is needed. The LTE system defines transmission diversity as an alternative transmission scheme for seven common transmission modes because it is the transmission diversity which is the most insensitive to the channel variation among the various reference transmission schemes.

Transmission modes 1 through 6 listed in Table 1 support CRS-based transmission, while transmission modes 7 through 10 correspond to DRS (Antenna Port 5) or DM-RS (Antenna Ports 7, 8, 9, , 11, 12, 13, 14).

The CRS-based reference transmission scheme includes a single antenna transmission corresponding to a case where the transmitter has only one transmission antenna; Antenna port 0, transmit diversity to obtain spatial diversity, open-loop spatial multiplexing for spatial multiplexing transmission without feedback on spatial channel state, closed-loop spatial multiplexing for spatial multiplexing transmission based on feedback on spatial channel state Multi-user multiple input multiple output (MIMO) that transmits a plurality of user signals to differently shaped beams in the same resource, and closed-loop rank-1 precoding that performs single layer transmission based on feedback on spatial channel conditions .

In addition, the LTE system allows DRS to estimate the channel response using one common transmission mode, where DRS is referred to as RS for antenna port 5, and single antenna transmission; It is called antenna port 5 scheme.

In release-9 of LTE system, transmission mode 8 is added. Antenna ports 7 and 8, which are DM-RSs, are introduced and support spatial multiplexing based on DM-RS instead of CRS.

In LTE-A system (release-10), transmission modes 9 and 10 were added. To support up to 8 layer spatial multiplexing, antenna ports 9, 10, 11, 12, 13 and 14 are defined as additional DM-RSs at antenna ports 7 and 8, which are DM-RSs.

In short, LTE-A system supports transmission modes 1 ~ 6, which are CRS-based transmission modes, and transmission modes 7 ~ 10, which are transmission modes based on DM-RS including DRS.

The transmitter of the LTE system and the LTE-A system transmits the CRS in all subframes. Therefore, the receiver can receive the CRS in all subframes and use it for channel estimation of the data signal. However, there is one exception: in the MBSFN subframe to support MBSFN transmission, no CRS is transmitted in the data channel region. MBSFN transmission is a transmission scheme that broadens the service area of broadcasting by transmitting the same broadcast signal in multiple cells. The MBSFN transmission is required to transmit the same RS in multiple cells in order to allow a receiver to perform coherent demodulation without distinguishing cells transmitted simultaneously from multiple cells.

In the MBSFN subframe, only the MBSFN dedicated RS is defined and transmitted. Therefore, the receiver of the LTE system receiving the unicast service does not receive the data channel signal in the MBSFN subframe because the CRS is not transmitted in the MBSFN subframe. For this operation, the transmitter informs the receiver of the LTE system that the unicast service is received by the upper signaling of the MBSFN subframe, and the receiver recognizes which subframe is the MBSFN subframe in advance.

4 is a diagram showing time division multiplexing of MBSFN subframes.

Referring to FIG. 4, it can be seen that the normal subframe 251 and the MBSFN subframe 253 are time-divided. At this time, the receiver extracts the CRS from the normal subframe 251 and estimates the channel of the data signal. On the other hand, the receiver does not receive the data channel signal in the MBSFN subframe 253.

With this feature, the MBSFN subframe can be utilized as an optimized resource for the receiver in the LTE-A system. Since the LTE-A system must maintain backward compatibility with the LTE system, the transmitter must transmit the CRS in the normal subframe. However, the receiver of the LTE-A system can set the transmission mode so that it does not refer to CRS for data channel signal reception. That is, in the receiver of the LTE-A system, the resources used for CRS transmission are abandoned resources. However, in the receiver of the LTE system, since the CRS is not expected to be transmitted in the data channel region of the MBSFN subframe, the receiver of the LTE system recognizes the LTE-A subframe as the MBSFN subframe. The receiver of the LTE-A system recognizes the LTE-A subframe as an optimized subframe for the LTE-A system. Since the CRS is not transmitted in the LTE-A subframe, the amount of resources allocated to the data channel signal increases in the receiver of the LTE-A system, thereby increasing the data transmission rate or improving the reception performance.

5 is a diagram illustrating time division multiplexing of an LTE-A subframe.

Referring to FIG. 5, it can be confirmed that the normal subframe 251 and the LTE-A subframe 255 are time-divided. The LTE-A subframe is recognized as an MBSFN subframe for the receiver of the LTE system while the receiver is recognized as the subframe optimized for the LTE-A system for the receiver of the LTE-A system. In the normal subframe 251, the transmitter must simultaneously transmit CRS and DM-RS for demodulation of the receiver of the LTE-A system for backward compatibility. In the data channel region of the LTE-A subframe 255, Only the DM-RS for the receiver of the LTE-A system can be transmitted.

In the DL of the LTE-A system, the transmitter transmits the CRS for the receiver of the LTE system and the DM-RS for the receiver of the LTE-A system. Here, DM-RS is an extension of DRS to support spatial multiplexing. And since it is assumed that the data signal can form up to eight spatial layers, up to eight orthogonal DM-RSs are defined. The main reason for introducing DM-RS is to allow the transmitter to apply arbitrary pre-coding. If the pre-coding is limited to the pre-coding codebook, it is not suitable for multi-user MIMO (MU-MIMO), and DCI for supporting CoMP JT becomes very complicated. In order to effectively support the transmission scheme to be improved or newly introduced in the LTE-A system, it is decided to introduce a new DM-RS instead of recycling the CRS.

However, in the normal subframe, the transmitter must also transmit the CRS for the receiver of the LTE system and the DM-RS for the receiver of the LTE-A system. Even if the transmission method of the LTE-A system using DM-RS is effective, if the two types of RSs are always transmitted, the amount of resources consumed by the RSs may be more than necessary. Therefore, there may occur a situation where the transmission method of the LTE-A system using the DM-RS causes a lower data transmission rate than the transmission method of the LTE system. Accordingly, even in the case of the receiver of the LTE-A system, the data rate can be improved by selectively receiving the data signal using the CRS as in the receiver of the LTE system.

In the DL of the LTE system, upper signaling is defined as shown in Table 2 below to set a transmission mode using multiple transmit antennas. That is, the upper signaling includes an information element for informing the receiver about the multiple transmit antennas for each receiver, which can be defined as 'AntennaInfoDedicated', for example. And 'AntennaInfoDedicated' includes a mode information element for defining a transmission mode of the LTE system. At this time, the mode information element can be defined as 'transmissionMode', and it indicates 3-bit information as to which transmission mode is set. If the mode information element 'transmissionMode' is set to tmA, it means that it is set to transmission mode A. For example, if tm3 is set, transfer mode 3 is set.

Transmission modes 9 and 10 were added in the DL of the LTE-A system. Therefore, the transmission mode can not be set to 'AntennaInfoDedicated' as shown in Table 2 above. Therefore, the receiver of the LTE-A system receives the upper signaling 'AntennaInfoDedicated-rel10' to be described later to grasp the transmission mode.

The first embodiment of the present invention defines both mode information elements 'transmissionMode-rel10' and 'transmissionModeMBSFN-rel10' as shown in Table 3 below. The mode information element 'transmissionMode-rel10' is intended to inform which transmission mode is set in a normal situation. Here, a general situation is a situation that can be commonly applied to a general subframe or an LTE-A subframe. If one of the transmission modes 7, 8, 9, and 10 is set, all subframes operate in a DM-RS based transmission mode. However, if one of the transmission modes 1, 2, 3, 4, 5, and 6 is set, it corresponds to the CRS-based transmission mode and can not be applied to the LTE-A subframe. That is, the receiver set in the CRS-based transmission mode can not receive the data channel signal in the LTE-A subframe.

To solve this problem, a mode information element 'transmissionModeMBSFN-rel10' is additionally defined. A mode information element 'transmissionModeMBSFN-rel10' consisting of 4-bit informs which transmission mode the receiver of the LTE-A system is set to in the LTE-A subframe. Since the CRS is not transmitted in the LTE-A subframe, One of transmission modes 7, 8, 9, and 10, which is an RS-based transmission mode, is selected.

The second embodiment of the present invention necessarily defines a mode information element 'transmissionMode-rel10' as shown in Table 4 below, but if the transmitter of the LTE-A system transmits a transmission mode indicated by the mode information element 'transmissionMode-rel10' The mode information element 'transmissionModeMBSFN-rel10' may be omitted if it is also intended to be maintained in the LTE-A subframe. Table 4 below shows an upper signaling structure called 'AntennaInfoDedicated-rel10' for supporting the present embodiment. and the transmissionModeMBSFN-rel10 is selectively set by the transmitter. In the present embodiment, if the receiver of the LTE-A system is set to the DM-RS based transmission mode and the transmissionModeMBSFN-rel10 is not set by the transmissionMode-rel10, the transmissionMode- RS-based transmission mode set by the DM-RS and receives the data channel signal.

In the third embodiment of the present invention, the transmission mode 7, which is a DRS-based transmission mode, is not supported in the mode information element 'transmissionModeMBSFN-rel10', but only the transmission modes 8, 9 and 10 are supported. That is, only one of the transmission modes 8, 9, and 10 is set in the LTE-A subframe. Table 5 below shows an upper signaling structure called 'AntennaInfoDedicated-rel10' for supporting the present embodiment.

The fourth embodiment of the present invention is a transmission mode 7, 8 (transmission mode) based on DRS or DM-RS defined in LTE release-8 and release-9 in the mode information element 'transmissionModeMBSFN-rel10' And support only the newly added transmission modes 9 and 10 in LTE-A. That is, only one of the transmission modes 9 and 10 is set in the LTE-A subframe. Table 6 below shows an upper signaling structure called 'AntennaInfoDedicated-rel10' for supporting the present embodiment. In this embodiment, 'transmissionModeMBSFN-rel10' is 1-bit information.

The fifth embodiment of the present invention allows all transmission modes to be set to 'transmissionModeMBSFN-rel10' as shown in Table 7 below. If one of the transmission modes 1, 2, 3, 4, 5, and 6, which is a CRS-based transmission mode, is set in the mode information element 'transmissionModeMBSFN-rel10', the receiver does not have a CRS in the data area of the LTE- And a CRS existing in a neighboring subframe, and receives a data channel signal transmitted in a CRS-based transmission scheme.

6 illustrates a transmitter structure according to an embodiment of the present invention. In this case, it is assumed that the transmitter has two transmit antennas, but the present invention is not limited to this. That is, the same applies even if the transmitter has more than two transmit antennas.

6, the transmitter 300 includes a transmission controller 301, a first multiplexer 303, a first pre-encoder 309, a second pre-encoder 313, a second multiplexer 315a, 3 multiplexer 315b, a first transmission antenna 317a, and a second transmission antenna 317b. At this time, the transmitter 300 multiplexes the data signal 303 and the DM-RS 305 or the CRS 311 and transmits the multiplexed signal. In the LTE-A subframe, the transmitter 300 transmits the DM-RS 305 in the data area, but the CRS 311 does not. In the normal subframe, the transmitter 300 transmits the CRS 311 to maintain backward compatibility and further, if necessary, the DM-RS 305 according to the transmission mode set in the receiver of the LTE-A system.

The transmission controller 301 determines whether the current subframe is an LTE-A subframe or a general subframe. If it is an LTE-A subframe, the transmission controller 301 controls to generate and transmit the data signal 303 and the DM-RS 305. At this time, the transmission controller 301 refers to the transmission mode for the LTE-A subframe set in the scheduled receiver to determine the DCI format. The number of DM-RSs 305 is determined by the number of spatial multiplexing layers and notifies the receiver through the DCI transmitted on the PDCCH.

On the other hand, if the current subframe is a normal subframe, the transmission controller 301 generates the DM-RS 305 if necessary according to the data signal 303 and the CRS 311 and the transmission mode set in the receiver of the LTE-A system . At this time, the transmission controller 301 determines the DCI format by referring to the general transmission mode set in the scheduled receiver. In the CRS-based transmission mode, the DM-RS 305 is not transmitted, and the pre-coding information used by the transmitter to transmit the data channel signal is notified through the DCI or is considered to be based on a preset transmission mode. The number of DM-RSs 305 is determined by the number of spatial multiplexing layers, and notifies the receiver through the DCI transmitted on the PDCCH.

The first multiplexer 307 multiplexes the data signal 303 and the DM-RS 305 and transmits the multiplexed data signal 303 and the DM-RS 305 to the first pre-encoder 309. The first pre-encoder 309 applies the same pre-coding to the DM-RS 305 and the data signal 303. The first multiplexer 307 multiplexes the data signal 303 and transfers the multiplexed data signal 303 to the first pre-encoder 309. The DM- The first pre-encoder 309 pre-encodes the data signal 303. At this time, the transmission controller 301 determines which pre-coding is to be applied to the specific receiver in the first pre-encoder 309.

When the CRS 311 is input, the second pre-encoder 313 applies fixed precoding fixed to the CRS 311. Here, the fixed pre-coding means not always changing the pre-coding according to the channel state of the receiver but always applying a constant pre-coding. The reason for applying the fixed pre-coding is that the LTE-A system can have up to 8 transmit antennas, but the receiver of the LTE system recognizes the LTE-A system as having up to 4 transmit antennas, Of the maximum number of CRSs of up to 8 transmit antennas. This process is called antenna virtualization. At this time, the second pre-encoder 313 determines how to place the CRS 311 on the first transmission antenna 317a and the second transmission antenna 317b.

 The second multiplexer 315a and the third multiplexer 315b receive the data signal 303 and the DM-RS 305 in response to the pre-coded data signal 303 and the DM-RS 305 in the first pre- RS 305, and transmits the multiplexed signal through the first transmission antenna 317a and the second transmission antenna 317b. Or the CRS 311 pre-coded by the second pre-coder 313 is input to the second multiplexer 315a and the third multiplexer 315b Multiplexes the data signal 303 and the CRS 311 and transmits the multiplexed data through the first transmission antenna 317a and the second transmission antenna 317b.

7 shows a receiver structure according to an embodiment of the present invention. In this case, it is assumed that the receiver includes two reception antennas, but the present invention is not limited thereto. Even if the receiver has more than two receive antennas.

7, a receiver 400 includes a reception controller 401, a first reception antenna 403a, a second reception antenna 403b, a first demultiplexer 405a, a second demultiplexer 405b, An estimator 407, a combiner 409, and a data processor 413.

The receiving controller 401 analyzes the upper signaling to determine whether the current subframe is an LTE-A subframe or a normal subframe. Also, the reception controller 401 refers to the transmission mode set in the receiver and the control information (DCI) transmitted through the PDCCH to determine the following matters.

i. The RS that should be used for channel estimation for demodulation is CRS or DM-RS? (Determined by the transmission mode previously set in the upper signaling)

ii. How many DM-RSs should be estimated if DM-RS is used for channel estimation for demodulation? (Determined by the DCI transmitted over the PDCCH)

iii. What format should the control signal (DCI) including data reception method and resource allocation information be supposed to receive and receive the PDCCH? (Determined by the transmission mode previously set in the upper signaling)

iv. How should the data channel signal be received from? (Determined by the DCI transmitted over the PDCCH)

The first demultiplexer 405a and the second demultiplexer 405b demultiplex the signals into RS and data signals when receiving signals from the first and second receiving antennas 403a and 403b. The first demultiplexer 405a and the second demultiplexer 405b transmit the RS to the channel estimator 407 at this time. The first demultiplexer 405a and the second demultiplexer 405b transmit the data signal to the combiner 409. [

The channel estimator 407 estimates a channel using the input RS. At this time, if it is determined that the current subframe is the LTE-A subframe, the reception controller 401 receives the PDCCH according to the transmission mode for the LTE-A subframe and obtains the DCI information, And instructs the channel estimator 407 to estimate the channel required for demodulating the data channel signal. However, if the transmission mode for the LTE-A subframe is not set or if the transmission mode for the LTE-A subframe is set to the CRS-based transmission mode, the reception controller 401 transmits the data channel signal in the LTE- It is regarded that it is not transmitted and the data channel signal reception process is terminated. However, in the fifth embodiment of the present invention, when the transmitter forcibly sets the data channel signal in the LTE-A subframe using the CRS existing in the control channel region and the neighboring subframe, The channel estimator 407 instructs the channel estimator 407 to estimate the channel using the CRS existing in the control channel region and the neighboring subframe.

If the reception controller 401 determines that the current subframe is a normal subframe, the reception controller 401 proceeds to data signal reception and channel estimation according to the transmission mode set in the mode information element "transmissionMode-rel10 ". If the CRS-based transmission mode is set in the "transmissionMode-rel10", the reception controller 401 receives the PDCCH according to the transmission mode and obtains the DCI information, and the channel estimator 407 estimates the data channel And instructs to estimate a channel necessary for signal demodulation. If the transmission mode is set to DM-RS based on "transmissionMode-rel10", the reception controller 401 receives the PDCCH according to the transmission mode and acquires the DCI information, and the channel estimator 407 uses the DM- And instructs to estimate a channel necessary for demodulating the data channel signal.

The channel estimator 407 estimates a channel by applying a channel estimation method according to a pattern of the RS indicated by the reception controller 401. The channel estimator 407 then passes the channel estimate to the reception controller 401. Accordingly, the reception controller 401 determines a coupling coefficient indicating how to couple the received data signal through the first reception antenna 403a and the second reception antenna 403b. The reception controller 401 also transfers this coupling coefficient to the combiner 409. [

Upon input of the data signal and the coupling coefficient, the combiner 409 appropriately combines the data signal according to the coupling coefficient to obtain the recovered data symbol 411. The data processor 413 performs demodulation and decoding on the data symbol 411 to recover the information bit stream. At this time, as the receiving controller 401 transmits the modulation and coding method notified by the DCI, the data processor 413 can perform appropriate demodulation and decoding.

A process for receiving the data channel signal of the data channel region in the receiver 400 will be described in detail.

8 is a flow chart illustrating the operation of a receiver applicable in the first, third, and fourth embodiments of the present invention.

Referring to FIG. 8, in step 501, the receiver of the LTE-A system first checks a mode information element, i.e., "transmissionMode-rel10" and "transmissionModeMBSFN-rel10", from the status information element of the upper signaling, that is, "AntennaInfoDedicated-rel10" . At this time, the receiver can recognize the transmission mode set in the receiver corresponding to the current subframe. Here, the receiver can determine from the mode information element that the receiver is set to the receiver in the transmission modes 1 to 10 in Table 1 above. In step 503, the receiver determines whether the current subframe is an LTE-A subframe.

If the current subframe is a normal subframe, the receiver assumes a normal subframe transmission mode set in "transmissionMode-rel10" in step 505 and receives the data channel signal. At this time, the receiver can receive the data channel signal according to any one of the transmission modes 1 to 10 in Table 1 above. On the other hand, if the current subframe is an LTE-A subframe, the receiver assumes an LTE-A subframe transmission mode set in transmissionModeMBSFN-rel10 in step 507 and receives a data channel signal. At this time, the receiver can receive the data channel signal according to any one of the transmission modes 7 to 10 in Table 1 above.

9 is a flow chart showing the operation of a receiver applicable in the second embodiment of the present invention.

9, in step 601, the receiver of the LTE-A system first checks a mode information element, i.e., "transmissionMode-rel10" and "transmissionModeMBSFN-rel10", from the status information element of the upper signaling, ie, "AntennaInfoDedicated-rel10" . At this time, the receiver can recognize the transmission mode set in the receiver corresponding to the current subframe. Here, the receiver can determine from the mode information element that the receiver is set to the receiver in the transmission modes 1 to 10 in Table 1 above. In step 603, the receiver determines whether the current subframe is an LTE-A subframe.

If the current subframe is a normal subframe, the receiver assumes the normal subframe transmission mode set in "transmissionMode-rel10" in step 605 and receives the data channel signal. At this time, the receiver receives a data channel signal according to any one of the transmission modes 1 to 10 in Table 1 above. If the current subframe is an LTE-A subframe, the receiver checks "transmissionModeMBSFN-rel10" in step 611 to determine whether a transmission mode for the LTE-A subframe is set. If the transmission mode for the LTE-A subframe is set, the receiver assumes the LTE-A subframe transmission mode set in "transmissionModeMBSFN-rel10 " If the transmission mode for the LTE-A subframe is not set, the receiver determines in step 615 whether the normal subframe transmission mode set in "transmissionMode-rel10" If the normal subframe transmission mode is CRS-based, there is no CRS in the LTE-A subframe, so the base station stops receiving the data channel signal in step 617. If the normal subframe transmission mode is based on DM-RS, the DM-RS can be transmitted to the LTE-A subframe. Therefore, the BS assumes a normal subframe transmission mode set in "transmissionMode- Signal.

10 is a flowchart showing the operation of a receiver applicable in the fifth embodiment of the present invention.

10, in step 701, the receiver of the LTE-A system first checks a mode information element, i.e., "transmissionMode-rel10" and "transmissionModeMBSFN-rel10", from the status information element of the upper signaling, ie, "AntennaInfoDedicated-rel10" . At this time, the receiver can recognize the transmission mode set in the receiver corresponding to the current subframe. Here, the receiver can determine from the mode information element that the receiver is set to the receiver in the transmission modes 1 to 10 in Table 1 above. In step 703, the receiver determines whether the current subframe is an LTE-A subframe.

If the current subframe is a normal subframe, the receiver assumes a normal subframe transmission mode set in "transmissionMode-rel10" in step 705 and receives the data channel signal. At this time, the receiver can receive the data channel signal according to any one of the transmission modes 1 to 10 in Table 1 above. If the current subframe is an LTE-A subframe, the receiver checks transmissionModeMBSFN-rel10 in step 721 and determines whether the transmission mode set for the LTE-A subframe is CRS-based. If the transmission mode for the LTE-A subframe is CRS-based, the receiver assumes the LTE-A subframe transmission mode set in "transmissionModeMBSFN-rel10" Estimates the channel using the CRS of the frame, and receives the data channel signal. At this time, the receiver can receive the data channel signal according to any one of the transmission modes 1 to 6 in Table 1 above. If the transmission mode for the LTE-A subframe is based on DM-RS or DRS, the receiver assumes the LTE-A subframe transmission mode set in transmissionModeMBSFN-rel10 in step 725 and receives the data channel signal. At this time, the receiver can receive the data channel signal according to any one of the transmission modes 7 to 10 in Table 1 above.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of the present invention in order to facilitate the understanding of the present invention and are not intended to limit the scope of the present invention. That is, it will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible.

Claims (18)

A method for receiving data in a user equipment (UE)
Receiving information on at least one transmission mode from among a plurality of transmission modes;
Receiving information on a MBSFN (Multimedia Broadcast Multicast Service Single Frequency Network) subframe;
Receiving downlink control information (DCI) on a data signal;
Determining at least one transmission scheme corresponding to a current subframe based on information on the at least one transmission mode, information on the MBSFN subframe, and the format of the DCI; And
Processing the data signal based on the transmission scheme;
Gt; The method according to claim 1,
Wherein at least one of the plurality of transmission modes is based on a common reference signal (CRS), and at least one of the plurality of transmission modes is based on a DM-RS (Demodulation Reference Signal) Way. The method according to claim 1,
Receiving the data signal based on at least one transmission mode for the MBSFN subframe when the current subframe is the MBSFN subframe; And
Receiving the data signal according to at least one transmission mode for the normal subframe when the current subframe is a normal subframe;
Further comprising the steps of: The method according to claim 1,
Wherein the format of the DCI includes information on a DM-RS (Demodulation Reference Signal). 2. The method of claim 1, wherein the at least one transmission mode is transmission mode 9 or transmission mode 10, and the format of the DCI is DCI format 1A. A method for transmitting data in a base station (BS)
Transmitting information on at least one transmission mode from among a plurality of transmission modes;
Transmitting information on an MBSFN (Multimedia Broadcast Multicast Service Single Frequency Network) subframe;
Transmitting downlink control information (DCI) for a data signal;
Determining at least one transmission scheme corresponding to a current subframe based on information on the at least one transmission mode, information on the MBSFN subframe, and the format of the DCI; And
Transmitting the data signal based on the transmission scheme
And transmitting the data. The method according to claim 6,
Wherein at least one of the plurality of transmission modes is based on a common reference signal (CRS), and at least one of the plurality of transmission modes is based on a DM-RS (Demodulation Reference Signal) Way. The method according to claim 6,
Wherein the format of the DCI includes information on a DM-RS (Demodulation Reference Signal). 7. The method of claim 6, wherein the at least one transmission mode is transmission mode 9 or transmission mode 10, and the format of the DCI is DCI format 1A. In the data receiving apparatus,
A receive controller and a data processor,
The receiving controller and the data processor,
Receiving, by the reception controller, information on at least one transmission mode from among a plurality of transmission modes;
Receiving, by the reception controller, information on a Multimedia Broadcast Multicast Service Single Frequency Network (MBSFN) subframe;
Receiving, by the reception controller, downlink control information (DCI) on the data signal;
Determine, by the receiving controller, at least one transmission scheme corresponding to a current subframe based on the information on the at least one transmission mode, information on the MBSFN subframe, and the format of the DCI;
The data processor processes the data signal based on the transmission scheme
To the data receiving apparatus. 11. The method of claim 10,
Wherein at least one of the plurality of transmission modes is based on a common reference signal (CRS), and at least one of the plurality of transmission modes is based on a DM-RS (Demodulation Reference Signal) Device. 11. The method of claim 10,
The receiving controller further comprises:
Receive the data signal based on at least one transmission mode for the MBSFN subframe when the current subframe is the MBSFN subframe;
When the current subframe is a normal subframe, receiving the data signal based on at least one transmission mode for the normal subframe
To the data receiving apparatus. 11. The method of claim 10,
Wherein the format of the DCI includes information on a DM-RS (Demodulation Reference Signal). 11. The apparatus of claim 10, wherein the at least one transmission mode is transmission mode 9 or transmission mode 10, and the format of the DCI is DCI format 1A. A data transfer apparatus comprising:
A transmission controller and a multiplexer,
The transmission controller and the multiplexer,
Transmitting, by the transmission controller, information on at least one transmission mode among the plurality of transmission modes;
Transmitting information on a Multimedia Broadcast Multicast Service Single Frequency Network (MBSFN) subframe by the transmission controller;
Transmitting downlink control information (DCI) for a data signal by the transmission controller;
Determine, by the transmission controller, at least one transmission scheme corresponding to a current subframe based on the information on the at least one transmission mode, information on the MBSFN subframe, and the format of the DCI;
The transmission controller transmits the data signal based on the transmission scheme
And the data transmission device is configured to transmit the data to the data transmission device. 16. The method of claim 15,
Wherein at least one of the plurality of transmission modes is based on a common reference signal (CRS), and at least one of the plurality of transmission modes is based on a DM-RS (Demodulation Reference Signal) Device. 16. The method of claim 15,
Wherein the format of the DCI includes information on a DM-RS (Demodulation Reference Signal). 16. The apparatus of claim 15, wherein the at least one transmission mode is transmission mode 9 or transmission mode 10, and the format of the DCI is DCI format 1A.

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