KR101306726B1 - Method Of Allocating Symbol For Pilot Signal, And Method For Transmitting and Receiving Signals Using The Subframe By The Same, In Mobile Communication System - Google Patents

Abstract

The present invention relates to an OFDM symbol arrangement method for a reference signal and a signal transmission / reception method in a mobile communication system using the subframe. According to the present invention, the symbols for the first and last reference signals are disposed within the first and last L symbols in the subframe, and the intervals between the symbols for the reference signals in the subframe are minimized. Through this, the channel estimation performance of the receiving side receiving the reference signal can be improved.

Subframe

Description

Symbol Placement Method for Reference Signal in Mobile Communication System, and Method for Transmitting and Receiving Signal Using Subframe According to Method of Allocating Symbol For Pilot Signal, And Method For Transmitting and Receiving Signals Using The Subframe By The Same, In Mobile Communication System}

1 is a diagram illustrating a structure of one slot used in the conventional uplink.

FIG. 2 is a diagram illustrating a structure where two slots constitute 1 TTI in the conventional uplink. FIG.

3 is a diagram illustrating a subframe structure in which a length of a reference signal symbol is set equal to a data transmission symbol according to an embodiment of the present invention.

4 is a diagram for explaining a method of arranging a symbol for a reference signal according to an embodiment of the present invention;

5 is a diagram illustrating a subframe structure in which the interval between each SB is set to have a uniform interval when the symbol for the reference signal is an SB;

6 is a diagram illustrating a structure for transmitting a data demodulation and channel quality estimation reference signal to a specific SB in a subframe structure shown in FIG. 5 according to one embodiment of the present invention;

7 is a diagram illustrating a subframe structure in which positions of each symbol used for a reference signal are set according to an embodiment of the present invention when SB is not used as a reference signal symbol.

8 and 9 illustrate a method of multiplexing reference signals when transmitting reference signals for data demodulation and channel estimation according to an embodiment of the present invention.

10 and 11 illustrate various subframe structures to which an embodiment of the present invention is applied.

12 is a diagram illustrating a subframe structure using LB for CQ reference signal transmission when SB is used for reference signal transmission according to one embodiment of the present invention.

FIG. 13 illustrates a preferred subframe structure when interpolation is possible between two subframes according to one embodiment of the present invention. FIG.

FIG. 14 is a diagram illustrating preferred subframe structures when interpolation is possible between two subframes and one LB is allocated for transmission of a reference signal for CQ according to an embodiment of the present invention. FIG.

FIG. 15 is a diagram showing a preferred subframe structure when interpolation is possible between two subframes according to one embodiment of the present invention, and SB is not defined for reference signal transmission. FIG.

FIG. 16 is a diagram illustrating a preferred subframe structure when an LB for transmitting a CQ reference signal is set as a first symbol and a last symbol in a subframe, and interpolation is performed for each subframe according to another embodiment of the present invention. .

The present invention relates to a structure used for transmitting and receiving a signal in a wireless communication system, and more particularly, to a method for efficiently arranging a symbol for a reference signal in a wireless communication system, and a signal transmission and reception method using a subframe accordingly.

In the conventional 3GPP LTE system, it is considered to use two short blocks (hereinafter, referred to as "SBs") in one slot for transmitting a reference signal or a pilot for uplink. Referring to the structure of the uplink slot including the SB as follows.

1 is a diagram illustrating a structure of one slot used in a conventional uplink.

As shown in FIG. 1, one slot includes two SBs and six long blocks (hereinafter, referred to as “LB”). The LB is used for transmission of a control signal or data signal, and the SB may be used for transmission of a reference signal for coherent demodulation, or like the LB, for transmission of a control signal or data signal. In most cases, however, the LB is considered to be used for data transmission, and the SB is considered to be used for transmission of a reference signal for demodulation and channel estimation thereof.

1 shows that one slot has a time axis length of 0.5 msec. If a transmission time interval (“TTI”), which is a basic unit for transmitting a signal in the uplink, has a length of 0.5 msec, one slot as shown in FIG. 1 has one subframe. Configure However, when 1 TTI is extended to have a length of 1 msec, the conventional 1 subframe structure simply has a structure of simply repeating the slot structure as shown in FIG. 1, as shown in FIG. 2.

FIG. 2 is a diagram illustrating a structure where two slots constitute one TTI in the conventional uplink.

That is, the conventional subframe structure includes four SBs for transmitting a reference signal and 12 LBs for transmitting data, as shown in FIG.

However, when the basic slot structure is repeatedly used as illustrated in FIG. 2, intervals between positions of reference signals through four SBs are different from each other, and thus, channel estimation performance may be degraded. In addition, data transmitted at a position faster on the time axis than the first SB (SB # 1 in FIG. 2) in one subframe (for example, data transmitted through LB # 1 in FIG. 2), and last For data transmitted at a position slower in the time axis than SB (SB # 4 in FIG. 2) (e.g., data transmitted via LB # 12 in FIG. 2), channel estimation using a reference signal received through SB Since it is difficult to use values (or estimated values by interpolation using them), performance degradation may occur in data demodulation.

In addition, when the SB is used for transmitting the reference signal, the length of the sequence allottable on the frequency axis is shorter than that of the LB, which may cause difficulty in cell planning.

In order to solve the problems described above, an object of the present invention is not limited to the symbol used for transmitting the reference signal to the SB, but to perform efficient signal transmission and reception by adjusting the interval, position, and number between the corresponding reference signal symbols. A method of arranging a symbol for a reference signal, a subframe structure according thereto, and a method of transmitting / receiving a signal using the subframe are provided.

In addition, the proposed subframe structure more specifically defines a layout of reference signals according to each use, and provides a method of efficiently multiplexing the reference signals.

According to an embodiment of the present invention for achieving the above object, a method of arranging a plurality of reference signal symbols in a sub frame, the first reference signal symbols of the plurality of reference signal symbols in the sub-frame Placing a second reference signal symbol among the plurality of reference signal symbols within the last L symbols of the subframe within the first L symbols of a frame; And adjusting the interval between the plurality of reference signal symbols to have a minimum difference.

In this case, the reference signal symbol may have the same size as the data symbol in the subframe, and adjusting the interval between the plurality of reference signal symbols may include the first reference signal symbol and the second reference signal. And arranging a symbol in the center of each slot of the subframe.

The adjusting of the interval between the plurality of reference signal symbols may include disposing an additional reference signal symbol between the first reference signal symbol and the second reference signal symbol. The symbol may be disposed at a position such that the interval between the plurality of reference signal symbols has a minimum difference.

In addition, one or more of the plurality of reference signal symbols may be used as a reference signal for measuring channel quality, and the reference signal for measuring channel quality may be transmitted through a scheduling band other than the data transmission band in the frequency domain. May be assigned. In addition, the symbol used for the reference signal for the channel quality measurement may include the reference signal for the channel quality measurement in a multiplexed form by either code division multiplexing or distributed frequency division multiplexing.

In addition, the subframe is a subframe capable of interpolation through reference signals received through successive subframes, and adjusting the interval between the plurality of reference signal symbols is performed in the continuous subframe. It may be set in consideration of the position between the reference signal symbols.

Meanwhile, in a method for transmitting and receiving a signal using a subframe structure including a plurality of reference signal symbols, according to another embodiment of the present invention, the plurality of reference signal symbols are data in the subframe. The subframe structure has the same size as that of a symbol for a symbol, and includes: a first reference signal symbol disposed in the center of a first slot of the subframe; And a second reference signal symbol disposed in the center of the second slot of the subframe.

In addition, according to another embodiment of the present invention, in a method for transmitting and receiving a signal using a sub frame structure including a plurality of symbols for reference signals, the sub frame structure is the first L of the sub frame. A first reference signal symbol disposed within the number of symbols; A second reference signal symbol disposed within the last L symbols of the subframe; And a third reference signal symbol including a reference signal used for data demodulation and channel quality estimation between the first reference signal symbol and the second reference signal symbol.

In this case, the subframe structure may be used for uplink signal transmission and reception.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description, together with the accompanying drawings, is intended to illustrate exemplary embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced.

The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without these specific details. In some instances, well-known structures and devices are omitted or shown in block diagram form around the core functions of each structure and device in order to avoid obscuring the concepts of the present invention. In the following description, the same components are denoted by the same reference numerals throughout the specification.

The reason for using the structure including two SBs in one slot in the uplink of the 3GPP LTE system as shown in FIG. 1 is through a reference signal transmitted using a sequence unique to each user equipment (UE) in the uplink. This is to increase the channel estimation performance compared to the case of using one LB in one slot when estimating the channel. However, as described above, one TTI, which is a unit of signal transmission, has a structure including two slots as described above, and the method of using an SB for transmitting a reference signal is a sequence of sequences applicable to the corresponding SB as described above. It has a disadvantage in that the length is limited. Therefore, a structure using only symbols of the same size all need to be proposed without separately defining the length of a symbol for transmitting a reference signal within one subframe.

FIG. 3 is a diagram illustrating a subframe structure in which a length of a reference signal symbol is set to be the same as a data transmission symbol according to an embodiment of the present invention.

Specifically, the subframe structure shown in FIG. 3 includes two slots having a length of 0.5 msec, and has a structure in which one reference signal symbol is disposed at the center of each slot. Further, in the subframe, LB # 4 and LB # 11 represent symbols for transmitting a reference signal, and this length can be set equal to the length of other symbols. In the case of using a subframe having the structure as shown in FIG. 3, the sequence length that can be used as the reference signal can be secured longer than in the case of using the SB.

Therefore, hereinafter, the symbol for the reference signal is not limited to the SB, and the symbol for the reference signal is the SB (hereinafter, referred to as an "SB structure" for clarity of description in both cases) and the SB without further definition. When used (hereinafter referred to as "LB only structure"), it will be described by applying each embodiment of the present invention. In addition, the term 'LB' in the above-described LB-only structure has a meaning only for the contrast with the above-described SB use structure, it can be seen that LB means a general symbol.

In addition, in the following detailed description, 'symbol' means that both SC-FDMA symbols in uplink mainly using SC-FDMA and OFDM symbols in downlink using OFDM are included.

Hereinafter, a method of arranging a symbol for reference signal according to an embodiment of the present invention that can be applied to both the above-described SB using structure and LB dedicated structure will be described first.

4 is a diagram for describing a method of arranging a symbol for a reference signal according to an embodiment of the present invention.

As shown in FIG. 2 and FIG. 3, when the symbols for the minimum and the last reference signal are arranged in the sub-frame, the interpolation value of the channel estimate value using the reference signal received through the symbol as described above cannot be used. This can happen. This corresponds to a symbol region located at a position earlier than the symbol for the first reference signal and a symbol region positioned at a position slower than the symbol for the last reference signal in the subframe.

Therefore, in one embodiment of the present invention, as shown by 1 in FIG. 4, the symbol for the first reference signal is disposed within the first L subframe within the subframe, and the symbol for the last reference signal is disposed within the last L subframe, thereby for the first reference signal. It is proposed to reduce the number of symbols located at a position earlier than the symbol and the number of symbols located at a position slower than the symbol for the last reference signal. Here, L may be set in various ways according to the requirements of the system. However, L may not be larger than the case in which the fourth symbol is set for the reference signal as compared with the case shown in FIG.

Further, in one embodiment of the present invention, it is proposed to arrange the symbols for the reference signal so that the gap difference between each symbol is minimized as indicated by 2 in FIG. The arrangement of the reference signal symbols may be adjusted by arranging the arrangement of the existing reference signal symbols in the center of each slot as shown in FIG. 3, and adding a reference signal symbol as described in the following example. It may also include. As described above, when the gap between the symbols for each reference signal is minimized, it is possible to prevent degradation of channel estimation performance that occurs as the gaps between the reference signals are different from each other.

A specific example of applying one embodiment of the present invention to the above-described SB-using structure and the above-described LB-only structure will be described below.

5 is a diagram illustrating a subframe structure in which the interval between each SB is set to have a uniform interval when the symbol for the reference signal is an SB (that is, in an SB usage structure).

Specifically, the subframe structure according to the embodiment of the present invention as shown in FIG. 5 is the first SB (ie, SB #) in the time axis direction among the SBs SB # 1 to SB # 4 used for the reference signal. 1) and the last SB (SB # 4) are arranged at the first symbol position and the last symbol position of the subframe. This prevents performance degradation caused by data being transmitted to a region (LB # 1 and LB # 12 of FIG. 2) in which the channel estimation value through the reference signal is difficult to use in the subframe structure shown in FIG. have.

In addition, in the sub-frame structure according to an embodiment of the present invention, the remaining SBs are arranged at positions where the intervals between the respective SBs have the same interval. Specifically, the spacing between each SB may be equally set to an interval including four LBs as shown in FIG. 5. As such, when the intervals between the reference signals are equally arranged, performance can be improved in channel estimation and interpolation using each reference signal.

On the other hand, when the reference signal transmitted through SB # 1 to SB # 4 shown in FIG. 5 is a reference signal (DM Pilot) for data demodulation, a frequency domain in which data is transmitted through each LB in each SB It may be multiplexed and transmitted through a localized FDM scheme. However, the reference signals transmitted through each SB need not be all DM reference signals, and some of the SBs may transmit reference signals used not only for data demodulation but also for channel quality estimation (CQ).

6 is a diagram illustrating a structure for transmitting a reference signal for DM and CQ to a specific SB according to an embodiment of the present invention in the subframe structure shown in FIG. 5.

Specifically, in the subframe structure shown in FIG. 6, (a) shows a structure for transmitting a reference signal for DM and CQ through the first SB, and (b) shows a reference signal for DM and CQ through the last SB. The structure for transmitting the signal is shown. As shown in (a) of FIG. 5, when the CQ reference signal is transmitted through the first SB of the subframe, the receiver may use the result of receiving the reference signal to use for scheduling in the next subframe. In the case of transmitting the channel estimation reference signal through the last SB of the subframe, as shown in (b) of FIG. 5, the receiving end may transmit a channel at a position closest to the next subframe in time. It may have an advantage of obtaining quality information.

On the other hand, the case where the above-described embodiment of the present invention is applied to the LB-only structure will be described.

7 is a diagram illustrating a subframe structure in which positions of each symbol used for a reference signal are set according to an embodiment of the present invention when SB is not used as a reference signal symbol.

In the LB dedicated structure according to the embodiment of the present invention as described above with reference to FIG. 3, setting of two symbols used for the reference signal is shown. However, such a structure may have a disadvantage in that performance deterioration due to channel estimation may increase in the case of a medium or high speed UE as the distance SB between reference signal transmission positions increases. . Therefore, in one embodiment of the present invention as shown in FIG. 7, an additional reference signal symbol (for example, LB # 7 of FIG. 7) is added to reduce the time interval between the reference signals to prevent degradation of the channel estimation performance. Suggest to define.

In the subframe structure according to the embodiment of the present invention, as shown in FIG. 7, the position of the first reference signal symbol is referred to as the first symbol LB # 1 of the subframe, and the position of the last reference signal symbol is referred to as a subframe. It is proposed to set to the last symbol LB # 14. This prevents performance degradation caused by data being transmitted to a region (LB # 1 and LB # 12 of FIG. 2) in which the channel estimation value through the reference signal is difficult to use in the subframe structure shown in FIG. have.

In addition, in the subframe structure according to the embodiment of the present invention as shown in FIG. 7, the symbol LB # 7 added for the reference signal is arranged at a position where the difference between the symbols of the other reference signals is minimized. Suggest that. Specifically, in FIG. 7, the interval between LB # 1 and LB # 7 is 5 symbols, the interval between LB # 7 and LB # 14 is 6 symbols, and the interval difference between each reference signal symbol is set to 1 symbol or less. This is illustrated by way of example. As such, when the intervals between the reference signals are arranged as evenly as possible, performance can be improved in channel estimation and interpolation using each reference signal.

Meanwhile, as described above, there may be a compromise between the requirement for arranging the reference signal symbols at the outermost part of the subframe and the requirement for setting the intervals between the reference signal symbols at equal intervals. It may be set to an advantage according to the degree of performance improvement. For example, in the case of setting the symbol for the last reference signal to LB # 13 instead of LB # 14 in the subframe structure shown in FIG. 7, the symbol for the reference signal is not set as the last symbol of the subframe, but for each reference signal. There may be an advantage that the interval between symbols can be set at equal intervals. In this regard, the subframe structure according to the embodiment of the present invention may have various forms, and the aforementioned L may be set in various ways.

On the other hand, in the sub-frame structure according to an embodiment of the present invention shown in FIG. 7, a reference signal transmitted through a reference signal symbol LB # 7 additionally set to improve channel estimation performance is data. It can be used not only as a reference signal for DM but also as a reference signal for CQ. As described above, when the DM and CQ reference signals are transmitted in the additional symbols, a method of multiplexing them will be described.

8 and 9 illustrate a method of multiplexing reference signals when transmitting reference signals for data demodulation and channel estimation according to an embodiment of the present invention.

Specifically, FIG. 8 illustrates a structure in which reference signals of respective users are multiplexed in the form of frequency division multiplexing (CDM) in LB # 7 transmitting DM and CQ reference signals among the subframe structures shown in FIG. have. In this case, the transmitted reference signal may be allocated and transmitted to the entire scheduling bandwidth of the corresponding UE to provide channel quality information. That is, the reference signal may be transmitted not only through the band allocated as the data transmission band to the UE but through the entire frequency band to be scheduled.

Meanwhile, FIG. 9 illustrates a structure in which reference signals of respective users are multiplexed in a distributed FDM format to LB # 7 transmitting DM and CQ reference signals among the subframe structures shown in FIG. It is shown. In this case, various repetition factors (RPs) of different subcarrier intervals to which the reference signal is allocated on the frequency axis may be applied. Specifically, FIG. 9 illustrates the case where the repetition coefficients are 2, 3, and 4 within the scheduling bandwidth, respectively. Accordingly, the interval in which the reference signal is allocated on the frequency axis can be adjusted.

According to one embodiment of the present invention described above with reference to FIGS. 7 to 9, as shown in FIG. 3, channel estimation performance deteriorates at medium speed or high speed due to a large interval between symbols used for a reference signal in the structure. May occur, thereby reducing the increase in the BLER or FER. However, as long as the features of the embodiments of the present invention described above with reference to FIGS. 7 to 9 are retained, various methods may be possible as follows.

10 and 11 illustrate various subframe structures to which an embodiment of the present invention is applied.

Specifically, (a) of FIG. 10 illustrates that the positions of the first reference signal symbol and the last reference signal symbol are located at the second symbol and the last to second symbol of the subframe on the time axis (when L = 2). The structure in which the reference signal symbol is placed in the last symbol of the first slot is shown. In addition, (b) of FIG. 10 shows an additional reference signal symbol when the positions of the first and last reference signal symbols are located at the third symbol and the last to third symbol of the subframe on the time axis (L = 3). As shown in FIG. 9A, the structure arranged at the last symbol of the first slot is shown. As described above, the position of the symbol of the first reference signal and the position of the symbol of the last reference signal in the subframe are preferable because the position at the outermost part of the subframe reduces the area where channel estimation values using them are not available. As described above, it may be variously set according to interpolation possibility between successive subframes, data transmission band allocation scheme, and the like. That is, the symbol for the first reference signal and the symbol for the last reference signal are set to be disposed within the first L symbols and the last L symbols in the subframe as described above, where L is varied according to the requirements of the system. Although it may be set, it is preferable that it is not larger than the case of setting the four symbols to the reference signal as shown in the conventional case of FIG.

Meanwhile, in case (a) of FIG. 11, when the positions of the first and last reference signal symbols are located in the first and last symbols of the subframe (L = 1), an additional reference signal symbol is placed in the first slot of the second slot. It shows the arrangement in the symbol. In addition, in the case of (b) of FIG. 11, the positions of the first and last reference signal symbols are positioned at the second symbol and the last to second symbol of the subframe (L = 2), and the additional reference signal symbols of FIG. As in a), the structure shown in the first symbol of the second slot is shown. Finally, in the case of (c) of FIG. 11, the first reference signal symbol and the last reference signal symbol are set as the first 3rd symbol and the last 3rd symbol of the subframe (L = 3), and the additional reference signal symbol is shown in FIG. 11. It shows the same setting as the case of (a).

As described above, in case of using a subframe having a dedicated LB structure, one cyclic prefix unit (hereinafter, referred to as “CP”) is allocated to the SB by converting two SBs into one LB in the existing subframe structure shown in FIG. 2. Since the length corresponding to ") remains, the CP length needs to be readjusted within the subframe. As a method of adjusting the CP length, a method of equally allocating the lengths of two remaining CPs to CPs of all LBs within a 1 ms TTI may be used. This has the advantage of covering a larger channel delay spread than the existing structure.

As another method, two remaining CPs are allocated to a symbol to which the CQ reference signal is allocated. This may have an advantage when the timing for which the CQ reference signal is warped only by the LB to which the CQ reference signal is allocated is updated by giving a larger margin to the LB to which the CQ reference signal is allocated.

On the other hand, in the following, when the SB is used for the reference signal transmission, examples of the case of applying other embodiments of the present invention will be described.

12 is a diagram illustrating a subframe structure in which an LB is used for transmitting a CQ reference signal when an SB is used for transmitting a reference signal according to an embodiment of the present invention.

That is, in one embodiment of the present invention shown in FIG. 12, an additional LB is allocated as a symbol for CQ only while the intervals between symbols for reference signals as shown in FIGS. 5 and 6 are maintained at equal intervals. The structure is shown. Specifically, in FIG. 12A, the case where LB # 1 is assigned as the CQ LB is shown. In FIG. 12B, LB # 6 is used as the CQ LB, and in FIG. In FIG. 12 (d), LB # 7 is shown as a case where LB # 12 is assigned as the CB LB.

As shown in FIG. 12, when an LB other than an SB is allocated to transmit a CQ-only reference signal, the CQ reference signal transmission to be allocated and transmitted not only in the data transmission band but also in the entire scheduling band may be allocated within a given time. It may have advantages over the case of power SB.

In addition, when the CQ reference signal is arranged at the beginning of a subframe as shown in FIG. 12A, channel information obtained through the CQ reference signal can be applied to scheduling in a subframe subsequent to the subframe. 12 (d), when the CQ reference signal is arranged at the end of the subframe, scheduling is performed due to quality measurement of a channel closest to the next subframe to be allocated to the scheduling bandwidth or the channel state of the entire band. From this point of view, resource allocation can be made with the most up-to-date information.

Meanwhile, in the embodiment of the present invention described above with reference to FIG. 12, the allocation of the LB for the CQ may be performed every subframe, but may be more preferably performed according to an appropriate period of the CQ measurement. For example, in a specific embodiment of the present invention, the subframe structure shown in FIG. 5 or 6 is used as the basic structure, and every 2 subframes (that is, the CQ reference signal transmission period is 2 subframes). Thus, a method of transmitting the CQ reference signal may be applied according to any one of the subframes shown in FIG. 12.

As described above, the method for arranging symbols for reference signals and subframe structures according to the embodiments of the present invention uses only reference signals received within one subframe for channel estimation, thereby interpolating channels by interpolation thereof. It is assumed that the assumption is made. However, in some cases, interpolation may be possible between reference signals received through successive subframes. In such a case, it may be advantageous to change the above-described subframe structure as follows.

FIG. 13 is a diagram illustrating a preferred subframe structure when interpolation is possible between two subframes according to one embodiment of the present invention.

If interpolation is possible between two subframes, the interval between reference signal transmission SBs can be reduced compared to the subframe structure according to the embodiment of the present invention as shown in FIG. The estimation performance can be improved. Specifically, when interpolation is possible between SB # 4 of the current subframe and SB # 1 of the next subframe in the subframe structure shown in FIG. 13, transmission is performed through symbols LB # 10 to LB # 12 therebetween. It is possible to improve the channel estimation performance for the data to be reduced, and to reduce the interval between each SB.

Meanwhile, a structure in which one LB is additionally allocated for CQ reference signal transmission in the subframe structure illustrated in FIG. 13 will be described below.

FIG. 14 illustrates interpolation between two subframes according to one embodiment of the present invention, and illustrates exemplary subframe structures in the case of allocating one LB for CQ reference signal transmission.

Specifically, (a) of FIG. 14 shows an LB for transmitting a CQ reference signal at the beginning of a subframe, and four SBs for transmitting a DM reference signal, taking into account interpolation between two subframes. FIG. 14 (b) shows an LB for transmitting a CQ reference signal at the end of a subframe and two SBs for transmitting a DM reference signal. In consideration of interpolation between frames, a structure positioned to minimize the difference between the gaps is illustrated.

In the above-described structure, the CB reference signal may be allocated to the LB for transmitting the CQ reference signal in a distributed frequency division multiplexing scheme or a code division multiplexing scheme over a scheduling band or an entire band. In addition, when the LB for transmitting the CQ reference signal is disposed at the initial position of the subframe as shown in FIG. 14A, a time margin for applying scheduling in the subsequent subframe can be secured. As shown in b), when the LB for transmitting the CQ reference signal is disposed at the last position of the subframe, channel information of the closest time can be obtained.

FIG. 15 is a diagram illustrating a preferred subframe structure in which interpolation is possible between two subframes according to an embodiment of the present invention, and in the case where SB is not defined for reference signal transmission (LB only structure).

That is, the subframe structure illustrated in FIG. 15 illustrates a structure to which an embodiment of the present invention is applied in an LB-only structure when interpolation using reference signals received through two subframes is possible as in FIG. 13. . Specifically, in comparison with the subframe structure shown in FIG. 7, the position of the last reference signal symbol is set to LB # 11, that is, the fourth symbol from the last (that is, set to L = 4). Equal intervals can be maintained through interpolation with the first reference signal OFDM. At this time, the interval between the symbols for each reference signal is reduced compared to the case of FIG. 7, so that the channel estimation performance can be improved.

Meanwhile, FIG. 16 illustrates a preferred subframe structure when the LB for transmitting the CQ reference signal is set as the first symbol and the last symbol in a subframe, and interpolation is performed for each subframe according to another embodiment of the present invention. One drawing.

That is, in FIG. 16A, the LB for transmitting the CQ reference signal is disposed at the final position of the subframe, and the SBs for transmitting the DM reference signal are arranged such that the gap difference between each other is minimized in the subframe. Shows a structure in which the first SB (SB # 1) and the last SB (SB # 4) are set to be disposed at the outermost side in the subframe. Also, FIG. 16B shows an LB for transmitting a CQ reference signal at an initial position of a subframe, and the SBs for transmitting a DM reference signal are mutually in the subframe as in FIG. 16A. The structure in which the difference between the gaps is minimized is shown, but the first SB (SB # 1) and the last SB (BS # 4) are set so as to be arranged at the outermost part in the subframe.

With this subframe structure, even in the case where interpolation is performed only within each subframe, it is possible to reduce an area that is difficult to use the channel estimate value through interpolation, and by periodically transmitting the CQ reference signal through the LB, channel quality for the entire band Measurement can be performed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The foregoing description of the preferred embodiments of the present invention has been presented for those skilled in the art to make and use the invention. Although the above has been described with reference to the preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that you can.

For example, in the above description, a "sub frame" is a unit having one transmission time interval (TTI) and has a time length of 1 msec, and a "slot" indicates a length of 0.5 msec included in each subframe. The branch has been described as being a unit, but it may have different terms or different lengths according to the specification of the communication system.

Accordingly, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

When performing signal transmission and reception using the subframe structure according to the embodiment of the present invention as described above, it is possible to perform efficient signal transmission and reception by improving the performance of channel estimation through the reference signal.

In particular, by using the above-described LB dedicated structure, the sequence length may not be restricted in application of a reference signal, and channel estimation performance may be improved for a medium speed or a high speed UE through an additional reference signal symbol.

Claims (9)

A method of arranging a plurality of symbols for a reference signal in a sub frame, Disposing a first reference signal symbol among the plurality of reference signal symbols within the first L symbols of the subframe, and a second reference signal symbol among the plurality of reference signal symbols within the last L symbols of the subframe; step; And And adjusting an interval between the plurality of reference signal symbols to have a minimum difference. The method of claim 1, The reference signal symbol has the same size as the data symbol in the subframe, Adjusting the interval between the plurality of reference signal symbols, Disposing the first reference signal symbol and the second reference signal symbol in the center of each slot of the subframe. The method of claim 1, Adjusting the interval between the plurality of reference signal symbols, Disposing an additional reference signal symbol between the first reference signal symbol and the second reference signal symbol, And the additional reference signal symbols are arranged at a position such that the interval between the plurality of reference signal symbols has a minimum difference. The method of claim 1, One or more of the plurality of reference signal symbols are used for a reference signal for channel quality measurement, The reference signal for measuring the channel quality is a symbol resource allocation method for a reference signal, the frequency resource is allocated to be transmitted through a scheduling band other than the data transmission band in the frequency domain. 5. The method of claim 4, The symbol used for the reference signal for measuring the channel quality includes a reference signal for measuring the channel quality in the form of multiplexing by either code division multiplexing or distributed frequency division multiplexing. The method of claim 1, The subframe is a subframe capable of interpolation through a reference signal received through successive subframes. Adjusting the interval between the plurality of reference signal symbols, And a reference signal symbol arranging method in consideration of the position between the reference signal symbols in the continuous subframe. A method of transmitting and receiving a signal using a sub frame structure including a plurality of symbols for reference signals, the method comprising: The plurality of reference signal symbols have the same size as the data symbol in the subframe, The sub frame structure, A first reference signal symbol disposed in the center of the first slot of the subframe; And And a second reference signal symbol disposed in the center of the second slot of the subframe. A method of transmitting and receiving a signal using a sub frame structure including a plurality of symbols for reference signals, the method comprising: The sub frame structure, A first reference signal symbol disposed within the first L symbols of the subframe; A second reference signal symbol disposed within the last L symbols of the subframe; And And a third reference signal symbol including a reference signal used for data demodulation and channel quality estimation between the first reference signal symbol and the second reference signal symbol. 9. The method according to claim 7 or 8, The first reference signal symbol and the second reference signal symbol, Any one of an SC-FDMA symbol in the uplink and an OFDM symbol in the downlink.

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