KR20120015927A - Wireless communication system and method for processing reference signal - Google Patents

Abstract

PURPOSE: A method for managing a reference signal in a wireless communication system and a system thereof are provided to confirm a reference signal pattern or a system parameter received from a transmitting end even when the number of reference signal pattern per antenna port in a LTE-A system varies. CONSTITUTION: A base station determines a reference signal pattern according to the number of antenna ports(610). The base station transmits information on a determined reference signal pattern to a user equipment(615). The base station arranges the reference signal(620). The terminal identifies a reference signal pattern ID(630). The base station modulates OFMD(Orthogonal Frequency Division Multiplexing) symbol according to the reference signal pattern(640). The terminal extracts the reference signal and estimates a channel(650,660).

Description

Wireless communication system and method for processing reference signal in wireless communication system {WIRELESS COMMUNICATION SYSTEM AND METHOD FOR PROCESSING REFERENCE SIGNAL}

The present invention provides a method for notifying a receiver of which reference signal pattern the transmitter uses to transmit a signal when supporting a plurality of reference signal patterns based on frequency, time, space, and code resources in a cellular wireless mobile communication system. A device to perform is proposed.

The mobile communication system has evolved into a high speed, high quality wireless packet data communication system capable of providing data services and multimedia services, instead of providing voice-oriented services in the early days. Therefore, various mobile communication standards such as High Speed Downlink Packet Access (HSDPA) of 3rd Generation Partners Project (3GPP), High Speed Uplink Packet Access (HSUPA), High Rate Packet Data (HRPD) of 3GPP2, and 802.16 of IEEE Was developed to support wireless packet data transmission services.

Existing third generation wireless packet data communication systems such as HSDPA, HSUPA, HRPD, etc. use techniques such as Adaptive Modulation and Coding (AMC) and channel sensitive scheduling to improve transmission efficiency. Using 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 condition is not good, the transmitting end reduces the amount of data to be transmitted to adjust the reception error probability to a desired level. And if the channel condition is good, the transmitting end can increase the amount of data to be transmitted, and can effectively transmit a lot of information while matching the reception error probability to a desired level. By utilizing the channel sensitive scheduling resource management method, the transmitting end selectively services a user having a good channel condition among several users. Therefore, when using the AMC method, the system capacity is increased compared to allocating and serving a channel to one user. This increase in capacity is referred to as multi-user diversity gain. In addition, the AMC method and the channel sensitive scheduling method are a method of applying an appropriate modulation and coding scheme at a time point determined to be the most efficient by receiving partial channel state information from the receiving end.

Recently, studies are being actively conducted to convert code division multiple access (CDMA), which is used in second and third generation mobile communication systems, to orthogonal frequency division multiple access (OFDMA) in a next generation system. 3GPP and 3GPP2 have begun standardizing on evolutionary systems using OFDMA. It is known that the capacity can be increased in the OFDMA method as compared to the CDMA method. One of various causes of capacity increase in the OFDMA scheme is that frequency domain scheduling can be performed on the frequency axis. Just as channel gains are gained through channel-sensitive scheduling using characteristics that change over time, more capacity gains can be obtained when channels utilize characteristics that vary with frequency.

In order to increase the capacity gain through the various methods described above, information about the state of the wireless channel is required. And the receiving end should receive the reference signal transmitted by the transmitting end to measure the information on the channel state. To do this, the receiving end needs to know in which pattern the transmitting end transmits the reference signal on time, spatial frequency, and code resources.

As one example, in the 3GPP LTE system, since the reference signal pattern is determined based on the cell ID, the receiving end can know the pattern of the reference signal transmitted when the cell ID of the transmitting end is known.

In the LTE system, the receiving end can know the number of antenna ports, and since the pattern of the reference signal is limited, the transmitting end can easily know which pattern of reference signal to transmit. However, in the LTE-A system, since a plurality of reference signal patterns may be applied to one antenna port, it is difficult for the transmitter to inform the receiver which pattern to use in the same manner as the existing LTE system.

In the present invention, as in the LTE-A system, the number of reference signal patterns per antenna port may be different, and when there are a plurality of reference signal patterns, it is intended to propose a method of informing a receiver of which reference signal pattern to use.

In order to solve the above problems, the reference signal processing method of the present invention includes determining a reference signal pattern according to the number of antenna ports, arranging a reference signal according to the determined reference signal pattern, and the reference signal pattern. And modulating and transmitting the reference signal arranged to the terminal.

In addition, to solve the above problems, the reference signal processing method of the present invention comprises the steps of determining a reference signal pattern for receiving a reference signal from the base station, receiving a reference signal according to the determined reference signal pattern, And feeding back channel state information to the base station according to the received reference signal.

Next, in order to solve the above problems, the reference signal processing system of the present invention determines a reference signal pattern according to the number of antenna ports, modulates the reference signal arranged according to the reference signal pattern, and transmits to the base station. And the terminal for determining a reference signal pattern to receive the reference signal, receiving a reference signal according to the determined reference signal pattern, and feeding back channel state information to the base station according to the received reference signal. .

According to the present invention, even when the number of reference signal patterns per antenna port in the LTE-A system is different, the receiving end can identify the reference signal pattern through the reference signal pattern or system parameters received from the transmitting end.

1 is a diagram illustrating a channel state information reference signal pattern in an LTE-A system according to the present invention.
2 illustrates a modified antenna port of the channel state information reference signal pattern according to the first embodiment of the present invention.
3 illustrates a modified antenna port change of the channel state information reference signal pattern according to the second embodiment of the present invention.
4 is a diagram illustrating a pattern ID allocated to channel state information reference signal patterns in an LTE-A system according to a third embodiment of the present invention.
5 is a diagram illustrating an area occupied by PSS, SSS, PBCH, and DwPTS in LTE and LTE-A systems according to the present invention;
6 is a diagram illustrating a procedure according to an embodiment of the present invention.

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

Further, in describing the embodiments of the present invention in detail, an OFDM-based wireless communication system, in particular the 3GPP EUTRA standard will be the main target, but the main subject of the present invention is another communication system having a similar technical background and channel form. In addition, it is possible to apply with a slight modification in the range without departing greatly from the scope of the present invention, which will be possible in the judgment of those skilled in the art.

Through the following examples will be described a method of notification of the reference signal pattern proposed in the present invention.

1. When the transmitting end notifies the receiving end of the reference signal pattern

Let's take a look at a case in which the transmitting end informs the receiving end about the reference signal pattern to be used by the transmitting end. The transmitter informs the receiver of information about the reference signal pattern to be used by the transmitter through various signaling. In addition, signaling including information on the reference signal pattern may be transmitted through higher layer signaling such as RRC signaling, or may be transmitted through a physical layer control channel such as PDCCH. In addition, the signaling related to the reference signal includes not only information about the reference signal pattern but also at least one or more of the following contents.

1) Reference signal pattern: The transmitting end informs the receiving end of one or more bits of which pattern the reference signal is transmitted.

2) Transmission period of the reference signal: The transmitting end informs the receiving terminal how many ms the transmission period of the reference signal is, and consists of one or more bits, it can be notified in the manner shown in Table 1.

Table 1. Example of signaling indicating transmission period of reference signal

3) Subframe Offset: The transmitter informs the receiver of the offset to which subframe the reference signal transmitted in one frame is transmitted in one frame, and may be configured as shown in Table 2.

Table 2. Example of signaling that informs subframe offset of reference signal

4) Number of antenna ports: The transmitting end informs the receiving end how many antenna ports the reference signal is transmitted.

5) Power boosting factor of the reference signal: The transmitter informs the serving cell reference signal of the power to be used in the muted RE in relation to the PDSCH RE muting of the other cell reference signal RE (Position Element) position. At this time, the transmitter notifies how much power to deliver by signaling of 1 bit or more.

Reference signal pattern type: In case of TDD (Time Division Duplex), since there is a pattern for TDD in addition to the same pattern as FDD (Frequency Division Duplex), signaling that indicates whether a TDD pattern or a pattern common to FDD is transmitted Signaling with one or more bits.

1 is a reference signal pattern for channel state information of the LTE-A system according to the present invention. As shown in FIG. 1, the LTE-A system has a plurality of reference signal patterns according to the number of antenna ports. And it is assumed that both the transmitting end and the receiving end know the pattern of all reference signals.

The transmitter notifies the receiver of only the position of the reference signal for antenna port 0 in the reference signal pattern to be used by the transmitter. The receiver then finds the corresponding pattern against the known reference signal patterns. Accordingly, the receiving end can know which reference signal pattern the transmitting end uses. To this end, the transmitter informs the subframe offset in which the reference signal is transmitted in the frame, the number of OFDM symbols to be transmitted, the position in the frequency domain (that is, the number of subcarriers). In other words, the transmitter notifies the receiver of the position of the reference signal for antenna port 0 in the pattern of the reference signal to be used for transmission.

As shown in FIG. 1, between the patterns having the same number of antenna ports (for example, when the number of antenna ports is 2 as shown in FIG. Since it is different for each pattern of signals, it can be distinguished which pattern of reference signal is used. However, the position of the reference signal for antenna port 0 overlaps between patterns having different numbers of antenna ports (for example, when the number of antenna ports is 2 and 4). In this case, the transmitting end informs the receiving end of how many antenna ports the reference signal to use when transmitting the signal is. Accordingly, the receiving end may know which reference signal pattern to use at the transmitting end.

To this end, the transmitter may inform the receiver by configuring signaling as shown in Tables 3, 4, 5, and 6 below. The signaling may be transmitted as an upper layer signal, such as RRC (Radio Resource Control) signaling, or may be transmitted as a physical layer signal using a channel such as a physical downlink control channel (PDCCH).

Table 3. Example signaling method for reporting the number of antenna ports

Table 4. Example signaling method for reporting the number of antenna ports

Table 5. Example signaling method for reporting the number of antenna ports

Table 6. Example signaling method for reporting the number of antenna ports

Even though the LTE-A system informs the receiver of the location of antenna 0, the antenna port 0 is interposed between patterns having different numbers of antenna ports (for example, when the number of antenna ports is 2 and 4). The position of the reference signal may overlap. It is not clear at this time which pattern will be used when transmitting the reference signal. In this case, there may be a method for notifying the receiving end of how many antenna ports the reference signal to use when transmitting the signal is a reference signal. In addition, if the pattern is designed so that the reference signal positions for antenna port 0 do not overlap in the patterns of reference signals for different numbers of antenna ports, the transmitter uses a reference signal by simply notifying the position of antenna port 0. You can tell the receiver if you want to.

2 is a diagram illustrating changed channel state information reference signal patterns for each antenna port according to the first embodiment of the present invention. 3 is a diagram illustrating changed channel state information reference signal patterns for each antenna port according to the second embodiment of the present invention. 2 and 3 are patterns of the reference signal designed so that the position of the antenna port 0 proposed in the present invention does not overlap.

Unlike the method of indicating the position of the antenna port 0, in the reference signal pattern of FIG. 1, a pattern ID is assigned to each reference signal pattern, and the transmitting end can inform the receiving end of the corresponding pattern ID to indicate which reference signal pattern to use. have. This method will be described in more detail with reference to FIG. 4. FIG. 4 is a diagram illustrating a pattern ID allocated to channel state information reference signal patterns in an LTE-A system according to a third embodiment of the present invention.

As shown in FIG. 4, the reference signal patterns include 20, 10, 5, and 3 reference signal patterns for the antenna ports 2, 4, and 8 and the TDD only pattern, respectively, depending on the number of antenna ports. . Here, P0 means pattern number 0, and resource elements RE having the same color belong to the same pattern.

There are two ways to give a reference signal pattern as follows.

-When pattern ID is assigned for each pattern according to the number of antenna ports

-When giving a pattern ID by integrating the whole pattern

In the first case, as shown in Table 7, a pattern ID may be allocated for each pattern according to the number of antenna ports.

Table 7. Pattern ID assignment by pattern according to the number of antenna ports

In this case, since a maximum of 20 pattern IDs must be distinguished, the transmitting end may inform the receiving end of the pattern ID through 5 bits of signaling. In this case, however, the transmitting end must separately inform the receiving end how many antenna ports are used.

In the second case, the pattern ID can be assigned by integrating the entire pattern as shown below.

Table 8. When pattern patterns are given by consolidating all patterns

In this case, since a maximum of 38 pattern IDs need to be distinguished, the transmitting end may inform the receiving end of the pattern ID through 6 bits of signaling. Unlike the first case, the transmitter does not need to separately signal how many antenna ports the receiver uses.

Next, the transmitting end may group the patterns of the reference signal into a predetermined group, and signal the corresponding group ID to notify the receiving end. In this case, the receiver checks which group the pattern belongs to based on the group ID, and then the cell ID, subframe number (subframe offset) through which the reference signal is transmitted within the frame, and different CRS (LTE Rel-8 common reference signal). System parameters such as cell-specific frequency shift, system BW, and frame number can be used to determine which reference signal pattern in the group is actually used for transmission.

Table 9 is a table illustrating a method of grouping the reference signals shown in FIGS. 1 and 4.

Table 9. Example of grouping five reference signals

Table 9 illustrates a case in which five reference signals are grouped. When grouping as described above, since the data is classified into eight groups, the transmitter uses 3 bits of signaling to signal the group ID. When a pattern ID of 0 to 37 is assigned to the entire pattern, the receiving end receives the group ID of Table 9 and uses the system parameters used in the equation to calculate the values from 0 to 37 using one of Equations 1 and 2 presented. Determines one ID of the pattern ID.

Table 10. Example of Grouping Six Reference Signals

Table 10 shows an example of grouping six reference signals. Since the grouping is classified into eight groups in this way, the transmitter uses 3 bits of signaling to signal the group ID. When the pattern ID of 0 to 37 is assigned to the entire pattern, the receiving end receives the group ID shown in Table 10 and uses the system parameters used in the equation to select from 0 to 37 using one of the equations (3) and (4). Determine one of the pattern IDs.

Table 11. Example of grouping three reference signals

Table 11 shows an example of grouping three reference signals. Since the grouping is classified into 14 groups in this way, the transmitter uses 4 bits of signaling to signal the group ID. When a pattern ID of 0 to 37 is assigned to the entire pattern, the receiving end receives the group ID shown in Table 11 and determines one of the pattern IDs of 0 to 37 by using one of Equations 5 and 6 using system parameters. Done.

Table 12. Example of Grouping According to Placement of Reference Signal

Table 12 shows an example of grouping according to the arrangement of the reference signals. 1 and 4, the patterns occupying the OFDM symbols 9 and 10 for the antenna ports 2, 4, and 8 are composed of one or two groups. At this time, no more than 6 patterns belong to one group. And the rest of the patterns were properly divided into different groups. Since the patterns of the reference signal are concentrated in two OFDM symbols, the remaining power may be added to the reference signal of the corresponding cell when muting is applied.

When the reference signal patterns are grouped, since they are classified into eight groups, the transmitter uses 3 bits of signaling to signal the group ID. When a pattern ID of 0 to 37 is assigned to the entire pattern as shown in Table 12, the receiving end receives the group ID of Table 12 and uses the system parameter to determine the pattern ID of 0 to 37 through one of Equations 7 and 8 Decide on one of them.

In the methods of grouping the pattern IDs of the reference signals, the base station may not use all the reference signal groups but may use only specific groups in a specific situation. For example, when performing CoMP (Coordinated Multi-Point transmission), referring to Table 12, the transmitting end is a group 1, 2 only when there are two antenna ports, group 5 only when there are four antenna ports, In case of 8, only group 7 can be used. Therefore, the transmitting end assigns only group IDs again and transmits them through signaling of 2 bits. And the receiving end can determine the pattern of the reference signal using Table 13 and the equation based on this.

Table 13. Example 1 of using only some reference signal patterns

Based on Table 13, one of the pattern IDs from 0 to 20 is determined through one of Equations 9 and 10 below.

As shown in Table 13, a method of using only pattern IDs of some reference signals may determine a group as shown in Table 14 below. And the determination of the pattern ID can be determined in the same way as the equation described with Table 13. However, in Table 14, signaling of 3 bits is required for group ID signaling.

Table 14. Example 2 of using only some reference signal patterns

In addition, a more general form of grouping can be considered:

In reference signal patterns corresponding to one antenna port number, reference signal patterns are divided into two groups A and B. In this case, if the total number of reference signal patterns is N, group A has S _A = 3 * n (integer, n = 0, 1, 2, ...) reference signal patterns, and group B has S _B = N The -3 * n reference signal patterns belong. Then, the transmitting end may select the reference signal pattern included in any one of group A and group B, or may select the reference signal pattern from the entire reference signal pattern. At this time, as a method of selecting the reference signal pattern in the group, one of the pattern IDs in the group is determined through Equation (11).

Next, a method of determining a reference signal pattern when the receiving end knows only the number of antenna ports will be described. In this case, the number of antenna ports may be notified to the receiver by the transmitter through higher layer or physical layer signaling, but the receiver may implicitly know through other signals without giving any signaling. In this case, the receiver defines a cell ID, a subframe number (subframe offset) through which a reference signal is transmitted within a frame, and a different LTE Rel-8 common reference signal (CRS) among patterns corresponding to the number of antenna ports. System parameters such as specific frequency shift, system BW, and frame number are used to determine which reference signal pattern is used. For example, when the case of the pattern ID of Table 7 is considered, the pattern ID may be determined through Equation 12.

In this case, only some patterns may be used. For each antenna port number, the patterns shown in Table 13 may apply. And the receiver determines the pattern ID using the following equation based on Table 13.

2. The sender To the receiving end  If you do not inform about the reference signal pattern

Next, a case in which the transmitting end does not notify the receiving end of the reference signal pattern to be used by the transmitting end will be described. In other words, the transmitter does not signal the reference signal pattern to be used, and the receiver defines a Cell ID, a subframe number (subframe offset) through which the reference signal is transmitted in the frame, and different LTE Rel-8 common reference signals (CRSs). Based on system parameters such as cell-specific frequency shift, system BW, and frame number, we will consider a method of implicitly knowing the reference signal pattern to be used by the transmitter. In this case, it is assumed that the receiving end knows the number of antenna ports. In this case, the transmitting end may inform the number of antenna ports, and the receiving end may implicitly find out from other signaling. In addition, although the transmitting end may not inform the information about the reference signal pattern, it may be notified through signaling configured including at least one or more of the following contents related to the reference signal.

1) Reference signal pattern: The transmitting end informs the receiving end of one or more bits of which pattern the reference signal is transmitted.

2) Transmission period of the reference signal: The transmitting end informs the receiving end how many ms the transmission period of the reference signal is, and consists of one or more bits. In addition, the transmitting end may inform the method as shown in Table 15.

Table 15. Example of signaling indicating transmission period of reference signal

3) Subframe Offset: The transmitter informs the receiver of the offset in which subframe the reference signal is transmitted in one frame. The subframe offset of the reference signal can be configured as shown in Table 16 below.

Table 16. Example of signaling that informs subframe offset of reference signal

4) Number of antenna ports: The transmitting end informs the receiving end how many antenna ports the reference signal is transmitted from.

5) Power boosting factor of the reference signal: The transmitter informs the serving cell reference signal of the power to be used in the muted RE in relation to the PDSCH RE muting of the other cell reference signal RE position. In addition, the transmitter notifies how much power will be delivered by signaling of 1 bit or more.

6) Reference signal pattern type: In the case of TDD, since there is a pattern for TDD in addition to the same pattern as FDD, the transmitting end transmits signaling to the receiver indicating whether a pattern for TDD or a pattern common to FDD is transmitted. At this point, the transmitter signals one or more bits.

When the pattern of the reference signal is not grouped and classified only by the number of antenna ports, and the pattern of the reference signal is confirmed, the transmitting end does not inform the receiving end of the number of antenna ports to the receiving end through signaling, and the receiving end receives the reference signal from other signaling. Same as the case of implicitly finding a pattern.

When the patterns of the reference signals are grouped, it is similar to the grouping method described above. However, even if the pattern of the reference signal is grouped, the transmitter does not directly signal information related to the corresponding group ID to the receiver.

The following examples are a method of grouping the reference signals shown in FIGS. 1 and 4.

Table 17. Example of grouping five reference signals

Table 17 shows an example of grouping five reference signals. When pattern IDs are assigned to each antenna when the total number of antenna ports is the same, the receiver determines a group ID of Table 17 by using Equation 14 according to a system parameter with respect to the known number of antenna ports. In addition, the receiving end determines one of the pattern IDs through one of Equations 15 and 16 according to the finally used system parameter.

Table 18. Example of Grouping Six Reference Signals

Table 18 shows an example of grouping six reference signals. When pattern IDs are assigned to each antenna when the total number of antenna ports is the same, the receiver determines a group ID of Table 18 by using Equation 17 on the number of known antenna ports based on system parameters. The receiver determines one of the pattern IDs through one of Equations 18 and 19 according to the system parameter finally used.

Table 19. Example of Grouping Three Reference Signals

Table 19 shows an example of grouping three reference signals. When pattern IDs are assigned to each antenna when the total number of antenna ports is the same, the receiver determines a group ID of Table 19 through Equation 20 based on a system parameter with respect to a known number of antenna ports. The receiver determines one of the pattern IDs through one of Equations 21 and 22 according to the finally used system parameter.

Table 20. Example of Grouping According to Placement of Reference Signal

Table 20 shows an example of grouping according to the arrangement of reference signals. 1 and 4, the patterns occupying the OFDM symbols 9 and 10 for the antenna ports 2, 4, and 8 are composed of one or two groups. At this time, no more than six patterns belong to one group. The remaining patterns are then properly distributed to other groups. As such, the reference signal patterns are concentrated in two OFDM symbols, so that power remaining when muting is applied may be added to the reference signal of the corresponding cell.

When the number of antenna ports in the entire pattern is the same, when the pattern IDs are assigned to each other, the receiving end determines the group ID of Table 20 through Equation 23 based on the system parameter with respect to the known number of antenna ports. The receiving end determines the pattern ID through one of Equations 24 and 25 according to the finally used system parameter.

In the above methods of grouping the pattern ID of the reference signal, the base station may not use all the reference signal groups, but may use only specific groups in a specific situation. For example, in case of CoMP, as shown in Table 20, the receiving end is a group in the case of two antenna ports in the case of two antenna ports, only in groups 1 and 2, and in the case of four antenna ports in the case of four antenna ports. If 10,000 antenna ports are used, only group 1 can be used for eight antenna ports. And only the corresponding groups are given the group ID again, the receiving end can determine the pattern of the reference signal using Table 21 and Equations 26 to 28.

Table 21. Example 1 of using only some reference signal patterns

Based on Table 21, the pattern ID of the table is determined by one of Equations 26 to 28 below.

As shown in Table 21, a method of using only pattern IDs of some reference signals may determine a group as follows. Determination of the pattern ID can be determined in the same manner as in Equations 26 to 28 mentioned with Table 21. However, in Table 22, the number of reference groups belonging to one antenna port is represented by Equation 29.

Table 22. Example 2 of using only some reference signal patterns

A more general form of grouping might be to consider the following: In the reference signal patterns of one antenna port number, the reference signal patterns are divided into two groups A and B. In this case, if the number of all reference signal patterns is N, S _{A in} group _A = 3 * n (integer, n = 0, 1, 2, ...) reference signal patterns belong, and S _B = N-3 * n reference signal patterns belong to group B. The transmitting end may select the reference signal pattern only in one of the group A and the group B, or may select the reference signal pattern in the entire reference signal pattern. At this time, one pattern of the pattern IDs in the group is determined through Equation 30.

3. A method for resolving conflicts with a specific reference signal pattern, a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel (PBCH), and a downlink pilot time slot (DwPTS)

In the above, the method of allowing the receiver to know the reference signal patterns that the transmitter uses to transmit the signal has been discussed. In the transmission of a reference signal, another consideration is that transmission of a reference signal of a specific pattern with a corresponding signal or channel may cause a collision in a subframe in which a specific signal or channel is transmitted. For example, when the transmission period of the reference signal is 5ms, if the reference signal has an offset of 0 in the frame, the reference signal is transmitted in subframe 0 at first and collides with the PSS, SSS, and PBCH, and the second time is 5times. Transmitted in subframe may collide with PSS and SSS. In addition to this case, the reference signal transmitted at this time does not collide with the subframe offset within the transmission period or frame, but the next reference signal to be transmitted may collide with a special signal or channel. In this case, when a reference signal is transmitted, another method may be applied when the signal collides with a special signal or channel, or a transmission cycle or subframe offset may be determined so as to avoid a collision in the first place. .

5 is a diagram illustrating an area occupied by PSS, SSS, PBCH, and DwPTS in LTE and LTE-A systems according to the present invention. In more detail, FIG. 5 shows signals and channels with the possibility of colliding with a specific pattern of the referenced reference signal.

In both FDD and TDD, PSS, SSS, and PBCH may collide with a specific pattern of a reference signal. In the case of TDD, the DwPTS part is not transmitted in the special subframe. Therefore, the pattern of the reference signal existing in the region cannot be transmitted in the special subframe. In the case of PBCH, both FDD and TDD are transmitted in 6 RBs (Resource Block) of the center of bandwidth in subframe # 0 every frame. In the case of PSS, FDD is transmitted in 6 RB of the center of bandwidth in OFDM symbol 6 in subframes 0 and 5, and in OFDM symbol 2 in subframes 1 and 6 in TDD. The SSS is transmitted in OFDM symbol # 5 in subframes 0 and 5 in the case of FDD, and is transmitted only in the central 6RB like PSS. TDD is transmitted in OFDM symbol # 13 in subframes # 0 and # 5. Therefore, a collision may occur when some of the patterns of the reference signal are transmitted in subframes such as the PSS, SSS, and PBCH, so a solution is required.

In order to solve this problem, a method of transmitting a reference signal avoiding a corresponding subframe is proposed. Signals, channels and DwPTSs for synchronization acquisition are only transmitted in some subframes within a frame. Therefore, the collision between the reference signal and the special signal and the channel can be resolved by not transmitting the reference signal in the corresponding subframe.

In this case, subframe numbers capable of transmitting reference signals in FDD and TDD are shown in Table 23 below.

Table 23. Subframe Numbers That Can Send Reference Signals

Accordingly, the transmitter does not transmit the reference signal except the subframes that can be transmitted in Table 23.

Next, when a reference signal is transmitted in the corresponding subframe, a method of transmitting except for a partial region may be proposed. Signals, channels, and DwPTSs for synchronization acquisition are transmitted only in some subframes within one frame, and are transmitted only in subcarriers corresponding to six RBs in the center even in one OFDM symbol. Therefore, when the reference signal is transmitted in the corresponding subframe, collisions can be resolved by not transmitting the reference signal in six RB regions in which PSS, SSS, and PBCH are transmitted. However, in the case of TDD, since the DwPTS is in the entire band, the reference signal is not transmitted in the subframe in which the DwPTS is transmitted.

In this case, Table 24 shows how reference signals can be transmitted in FDD and TDD, respectively.

Table 24. Subframe Numbers That Can Transmit Reference Signals Across Full Band

Next, a method for not using a pattern of some reference signals may be proposed in the corresponding subframe. Signals, channels, and DwPTSs for synchronization acquisition are transmitted only in some subframes within one frame, and are transmitted only in subcarriers corresponding to six RBs in the center even in one OFDM symbol. Therefore, when transmitting a reference signal in the corresponding subframe, there is a method of not using the six RB regions in which PSS, SSS, and PBCH are transmitted and the reference signals transmitted in the DwPTS region.

In addition, there may be a method of not using a pattern of reference signals colliding in the corresponding subframe. In more detail, there is a method of not using only reference signals that collide with PSS, SSS, PBCH, etc. in a subframe.

The availability of each reference signal pattern in each subframe based on the reference signal pattern shown in FIG. 4 may be illustrated as shown in Table 25 below.

Table 25. Availability of Each Reference Signal Pattern in a Specific Subframe

In each subframe, only reference signal patterns marked as usable are used as illustrated in Table 25, and the transmitter selects one reference signal pattern among the reference signal patterns marked as usable to transmit the reference signal.

Table 25 shows which reference signals are available for specific subframes. Based on this, when using reference signals colliding with PSS, SSS, PBCH, etc. in a specific subframe, a method of applying a different reference signal pattern only in the central 6RB region to collide is proposed. That is, in the subframe in which PSS, SSS, and PBCH are transmitted, the band without PSS, SSS, and PBCH transmits all existing reference signals, and in the band in which PSS, SSS, and PBCH is transmitted, as shown in Table 26 and Table 27 below. Transmit the reference signal by changing the signal pattern.

Table 26. Example of Changing Reference Signal Patterns in Some Bands of Specific Subframes

Table 27. Example of Changing Reference Signal Patterns in Some Bands of Specific Subframes

6 is a diagram illustrating a procedure according to an embodiment of the present invention.

In FIG. 6, a transmitting end is described as a base station (eNB) and a receiving end is referred to as a user equipment (UE).

Referring to FIG. 6, in step 610, the base station 602 determines a pattern of a reference signal (CSI-RS) according to the number of antenna ports. In addition, when the terminal 605 informs the terminal of the pattern of the reference signal, the base station 602 receives information on the pattern of the reference signal determined in step 615 (number of antenna ports, reference signal pattern ID, or reference signal pattern group ID). And the like) to the terminal 605. However, when information about the pattern of the reference signal is not known, the base station 602 does not directly transmit the information about the reference signal pattern to the terminal 605. Next, the base station 602 allocates a reference signal in step 620 and maps a Physical Downlink Shared Channel (PDSCH) resource element (RE).

When the information on the pattern of the reference signal is received, the terminal 605 detects the reference signal pattern ID using the information on the pattern of the reference signal received in step 630 and system parameters. On the other hand, when information on the pattern of the reference signal is not received, the terminal 605 determines the reference signal pattern ID by using a system parameter.

Next, the base station 602 modulates and transmits an OFDM symbol including a reference signal and data according to the reference signal pattern determined in step 640. Then, the terminal 605 receives the OFDM modulated signal from the base station 602 in step 650. In this case, when the reference signal is received through the OFDM modulated signal, the terminal 605 extracts the reference signal (CSI-RS) in step 660 and estimates a channel. In step 670, the terminal 605 feeds back channel quality information (CQI) / Reporting Interval (RI) / Precoding Matric Index (PMI). In step 680, the base station 602 receives feedback information from the terminal 605.

When data is received through the OFDM modulated signal, the terminal 605 extracts a demodulation reference signal (DM-RS) and estimates a channel in step 690. Next, the terminal 605 demodulates the PDSCH using the data demodulation reference signal in step 695.

The embodiments of the present invention disclosed in the present specification and drawings are intended to be illustrative only and not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention can be carried out in addition to the embodiments disclosed herein.

Claims (19)

In the reference signal processing method of the base station in the LTE-A system,
Determining a reference signal pattern according to the number of antenna ports;
Disposing a reference signal according to the determined reference signal pattern;
And modulating the reference signal arranged according to the reference signal pattern and transmitting the modulated reference signal to a terminal. The method of claim 1, wherein the determining of the reference signal pattern comprises:
And informing the terminal of the determined reference signal pattern. The method of claim 2, wherein the informing of the reference signal pattern is performed.
And indicating the position of antenna port 0. The method of claim 2, wherein the informing of the reference signal pattern is performed.
And assigning a pattern ID to the reference signal pattern, and informing the terminal of the pattern ID. The method of claim 2, wherein the informing of the reference signal pattern is performed.
And assigning a group ID by grouping the reference signal pattern into a group, and informing the terminal of the group ID. The method of claim 1, wherein the transmitting of the reference signal to a terminal is performed.
And transmitting the reference signal in a subframe in which the reference signal is transmitted, except for at least one signal for synchronization acquisition and a region in which a channel is transmitted. The method of claim 1, wherein the transmitting of the reference signal to a terminal is performed.
And transmitting the reference signal using only the available reference signal patterns identified in advance. The method of claim 1, wherein the transmitting of the reference signal to a terminal is performed.
And transmitting the reference signal by changing a reference signal pattern in a region in which at least one signal for synchronization acquisition and a channel are transmitted in a specific subframe. In the LTE-A system reference signal processing method of the terminal,
Determining a reference signal pattern for receiving a reference signal from a base station;
Receiving a reference signal according to the determined reference signal pattern;
And feeding back channel state information to the base station according to the received reference signal. The method of claim 9, wherein the determining of the reference signal pattern comprises:
The reference signal processing method comprising the step of determining the pattern ID according to the number of antenna ports. The method of claim 9, wherein the determining of the reference signal pattern comprises:
And determining group ID and pattern ID according to the number of antenna ports. A base station for determining a reference signal pattern according to the number of antenna ports, modulating the reference signal arranged according to the reference signal pattern, and transmitting the modulated signal to a terminal;
A reference signal processing configured to determine a reference signal pattern to receive the reference signal, receive a reference signal according to the determined reference signal pattern, and feed back channel state information to the base station according to the received reference signal system. The method of claim 12, wherein the base station
The reference signal processing system, characterized in that to inform the terminal of the antenna port 0 position of the determined reference signal pattern. The method of claim 12, wherein the base station
The reference signal processing system, characterized in that to give a pattern ID to the reference signal pattern, and to inform the terminal of the pattern ID. The method of claim 12, wherein the base station
And grouping the reference signal pattern into a group, granting a group ID, and informing the terminal of the group ID. The method of claim 12, wherein the base station
And transmitting the reference signal to the terminal except for a region for transmitting at least one signal and a channel for synchronization acquisition in a subframe in which the reference signal is transmitted. The method of claim 12, wherein the base station
And transmitting the reference signal to the terminal using only available reference signal patterns identified in advance. The terminal of claim 12, wherein the terminal
The reference signal processing system, characterized in that for determining the pattern ID according to the number of antenna ports. The terminal of claim 12, wherein the terminal
And a group ID and a pattern ID according to the number of antenna ports.

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