KR20090048316A - Method of transmitting and receiving pilot signal - Google Patents

Abstract

The present invention discloses an efficient data transmission and reception method and a pilot allocation structure for the same in a wireless access system. The method may include transmitting data using a resource block configured in consideration of channel estimation performance and data rate, and receiving data using the resource block. At this time, the resource block includes pilot symbols consisting of a predetermined number and a predetermined pattern.

Resource block, pilot symbol, OFDM symbol, subcarrier

Description

Method of transmitting and receiving pilot signal

The present invention relates to an efficient data transmission and reception method in a wireless access system. In addition, embodiments of the present invention disclose a pilot allocation structure for efficient data transmission.

The channel estimation method and pilot signal will be briefly described below.

In order to detect the synchronization signal, the receiver needs to know the information of the radio channel (such as attenuation, phase shift or time delay). In this case, the channel estimation refers to estimating the size and reference phase of the carrier. The wireless channel environment has a fading characteristic in which the channel state changes irregularly in time and frequency domain. Estimating amplitude and phase for these channels is called channel estimation. That is, channel estimation estimates the frequency response of the radio section or the radio channel.

As a channel estimation method, there is a method of estimating a reference value based on pilot symbols of several base stations using a two-dimensional channel estimator. In this case, the pilot symbol refers to a symbol having a high output, although it does not have actual data to help carrier phase synchronization and base station information acquisition. The transmitter and the receiver may perform channel estimation using the pilot symbol as described above. Channel estimation by the pilot symbol is to estimate the channel through a pilot symbol commonly known at the transmitting and receiving end, and to restore the data using the estimate.

44 is a diagram illustrating an example of a general pilot structure used in a single transmit antenna structure.

44 shows a case of one transmit antenna. In the case of one antenna, two pilot subcarriers are used in an even symbol and an odd symbol. In this case, the overhead by the pilot subcarrier may occur approximately 14.28%.

As described above, when using one transmit antenna, the pilot subcarrier has a pilot overhead of 14.28%. In the IEEE 802.16e system, which is a conventional technology, a different pilot subcarrier allocation structure is provided for each permutation scheme such as PUSC / FUSC / AMC. In addition, in the MIMO system as described above, the overhead of the pilot is quite large. In addition, one transmit antenna system has a pilot overhead of 10% or more, which severely degrades the data rate. The pilot subcarrier allocation structure according to the prior art is specified in IEEE 802.16e.

Commonly used permutation methods include Partial Usage of Subchannel (PUSC), Full Usage of Subchannel (FUSC), or Adaptive Modulation and Coding (AMC). In this case, the prior art has a different pilot subcarrier allocation structure for each permutation method (distributed / AMC).

This is because the permutation method has been separated in time, so that an optimized structure can be designed for each permutation. If permutation methods coexist in time, a unified basic data allocation structure is needed. In addition, in the prior art, there is a problem in that the pilot overhead is severe and the transmission rate is lowered. In the present invention, a method for transmitting and receiving pilot signals using an efficient pilot structure for a new system, for example, an IEEE 802.16 system, is presented.

Referring to FIG. 44, it can be seen that the overhead due to the pilot subcarriers in the Orthogonal Frequency Division Multiplexing (OFDM) system generally used is quite large. This pilot overhead can reduce link throughput and result in degraded system performance.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of general technology, and according to the present invention, there is provided an efficient data transmission method, and a pilot subcarrier allocation applicable to a system having a plurality of transmission antennas in order to increase the transmission rate. A structure may be provided, and a unified data allocation structure for various permutation methods may also be provided.

In order to solve the above technical problem, embodiments of the present invention disclose a data transmission method in an efficient wireless access system. In addition, embodiments of the present invention disclose a pilot subcarrier allocation structure for efficient data transmission.

In a wireless access system according to an aspect of the present invention, a method for transmitting and receiving data includes transmitting data using a resource block configured in consideration of channel estimation performance and data rate; And receiving data using the resource block, wherein the resource block includes pilot symbols composed of a predetermined number and a predetermined pattern.

In the above aspect, the RB may be configured of 4 subcarriers × 6 OFDMA symbols (hereinafter, all A subcarriers × B OFDMA symbols are represented by A × B). In this case, a pilot may be allocated only to the first OFDM symbol and the sixth OFDM symbol of the first subcarrier and the fourth subcarrier of the RB. Or, pilot is allocated only to a first OFDM symbol and a sixth OFDM symbol of a second subcarrier and a third subcarrier of the RB.

In one aspect of the above, the RB may have a 4x6 configuration of a subcarrier and an OFDM symbol. In this case, a pilot may be allocated only to a second OFDM symbol and a fifth OFDM symbol of the first subcarrier and the fourth subcarrier of the RB. Alternatively, pilots may be allocated only to the second and fifth OFDM symbols of the second and third subcarriers of the RB.

In one aspect above, pilots may be allocated in one OFDM symbol interval on the time axis. In this case, pilots may be allocated at intervals of three, nine, or thirteen subcarriers on the frequency axis. In this case, when pilots are allocated at intervals of three subcarriers on the frequency axis, the configuration of the resource block may be any one of 12 × 6, 12 × 12, and 6 × 12. Alternatively, when pilots are allocated at intervals of nine subcarriers on the frequency axis, the configuration of the resource block may be one of 18 × 6 and 18 × 3. Alternatively, when pilots are allocated at intervals of 13 subcarriers on a frequency axis, the configuration of the resource block may be 13 × 2.

In one aspect above, pilots may be allocated at intervals of two OFDM symbols on the time axis. In this case, pilots are allocated at intervals of six or nine subcarriers on the frequency axis. In this case, when pilots are allocated at intervals of six subcarriers on a frequency axis, the configuration of the resource block may be 18 × 3. Alternatively, when pilots are allocated at intervals of nine subcarriers on a frequency axis, the configuration of the resource block may be 9 × 6.

In one aspect above, pilots can be allocated at intervals of three OFDM symbols on the time axis. In this case, pilots may be allocated at intervals of one, three, four, or six subcarriers on the frequency axis. In this case, when pilots are allocated at intervals of one subcarrier on the frequency axis, the configuration of the resource block may be 6 × 12. Alternatively, when pilots are allocated at intervals of three subcarriers on the frequency axis, the configuration of the resource block may be 18 × 6. Alternatively, when pilots are allocated at intervals of four subcarriers on the frequency axis, the configuration of the resource block may be 12 × 6. Alternatively, when pilots are allocated at intervals of six subcarriers on the frequency axis, the configuration of the resource block may be any one of 6 × 6, 12 × 6, and 18 × 6.

In one aspect above, pilots may be allocated at six subcarrier intervals along the frequency axis.

In one aspect of the above, the resource block has a subcarrier and OFDM symbol configuration of 6 × 6, 6 × 12, 9 × 6, 9 × 12, 12 × 6, 12 × 12, 13 × 2, 18 × 3 , 18 × 6, and 26 × 2.

In the above aspect, the pilot symbols may be allocated as the same number to each OFDM symbol included in the resource block.

In one aspect above, to boost the power of the pilot symbols, power may be borrowed from data symbols included in the OFDM symbol to which the pilot symbols are assigned.

The pilot allocation structure disclosed in the embodiments of the present invention can efficiently transmit and receive data.

Embodiments of the present invention disclose data transmission methods using a pilot allocation structure in a wireless access system.

The following embodiments combine the components and features of the present invention in a predetermined form. Each component or feature may be considered to be optional unless otherwise stated. Each component or feature may be embodied in a form that is not combined with other components or features. In addition, some components and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment.

In the description of the drawings, procedures or steps which may obscure the gist of the present invention are not described, and procedures or steps that can be understood by those skilled in the art are not described.

In the present specification, embodiments of the present invention have been described based on data transmission / reception relations between a base station and a terminal. Here, the base station has a meaning as a terminal node of a network that directly communicates with the terminal. The specific operation described as performed by the base station in this document may be performed by an upper node of the base station in some cases.

That is, various operations performed for communication with a terminal in a network consisting of a plurality of network nodes including a base station may be performed by the base station or other network nodes other than the base station. In this case, the 'base station' may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), and an access point. In addition, the term “mobile station (MS)” may be replaced with terms such as a user equipment (UE), a subscriber station (SS), a mobile subscriber station (MSS), or a mobile terminal.

In addition, the transmitting end refers to a node transmitting data or voice service, and the receiving end refers to a node receiving data or voice service. Therefore, in uplink, a terminal may be a transmitting end and a base station may be a receiving end. Similarly, in downlink, a terminal may be a receiving end and a base station may be a transmitting end.

On the other hand, the mobile terminal of the present invention PDA (Personal Digital Assistant), cellular phone, PCS (Personal Communication Service) phone, GSM (Global System for Mobile) phone, WCDMA (Wideband CDMA) phone, MBS (Mobile Broadband System) phone And the like can be used.

Embodiments of the invention may be implemented through various means. For example, embodiments of the present invention may be implemented by hardware, firmware, software, or a combination thereof.

In the case of a hardware implementation, the method according to embodiments of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs). Field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of implementation by firmware or software, the method according to the embodiments of the present invention may be implemented in the form of a module, procedure, or function that performs the functions or operations described above. The software code may be stored in a memory unit and driven by a processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.

Embodiments of the present invention may be supported by standard documents disclosed in at least one of the wireless access systems IEEE 802 system, 3GPP system, 3GPP LTE system and 3GPP2 system. That is, steps or parts which are not described to clearly reveal the technical spirit of the present invention among the embodiments of the present invention may be supported by the above documents. In addition, all terms disclosed in the present document can be described by the above standard document. In particular, embodiments of the present invention may be supported by P802.16e-2005 or P802.16 Rev2 / D4 (April 2008), which is a standard document of the IEEE 802.16 system.

Specific terms used in the following description are provided to help the understanding of the present invention, and the use of the specific terms may be modified in other forms without departing from the technical spirit of the present invention.

The pilot allocation structure disclosed in the embodiments of the present invention may be designed in consideration of various factors. In addition, the pilot allocation structure disclosed in the embodiments of the present invention may be repeatedly applied to the time domain and the frequency domain within a frame or subframe.

For example, the pilot allocation structure may be designed in consideration of the interval in the time and frequency domains between the pilot symbols, the data transmission to pilot density, and the power ratio per symbol in consideration of power boosting.

Hereinafter, important factors considered in designing the pilot allocation structure will be described in detail.

1. Pilot symbol allocation interval

In pilot allocation structures according to the inventive concept, the spacing between pilot symbols is preferably maintained at 2 to 3 symbol intervals in consideration of a coherent time with respect to a moving speed (eg, 120 km). . In addition, it is desirable to have an effective coherence bandwidth within 8 to 9 subcarriers in consideration of frequency selective characteristics. However, such conditions may be adjusted according to a trade-off between channel estimation capability of the pilot and data rate.

The resource block (RB) used in the embodiments of the present invention is a set of resource elements (REs), and one resource block includes a plurality of subcarriers and a plurality of OFDM symbols. In this case, the resource element RE may indicate a resource allocation unit consisting of one subcarrier and one OFDM symbol. Hereinafter, the 'resource block' used in the present specification is used as the same meaning as the 'unit resource block'. Resource block (RB) and resource element (RE) is a term for properly representing the technical spirit of the present invention, it may be used corresponding to all resource allocation units performing the same function.

2. Power Boosting

Power boosting may be considered to improve the channel estimation performance of the terminal. For example, to boost the pilot symbol, clipping or back-off may be considered based on the boosted pilot power. If the clipping or the back-off is considered, the power loss may cause a performance degradation of the terminal.

Teaching or Puncturing data power may be used to boost the power of the pilot symbol. In this case, the channel estimation performance is increased, but if the channel situation is not good, the data processing capability may be degraded due to power loss of the data region. Among the methods for power boosting, various factors such as channel environment or overall performance can be considered in order to select the most suitable method. If the power of the data symbol is borrowed when boosting the power of the pilot symbol, the power difference for each OFDMA symbol may not occur.

However, if only the power of the pilot symbol is boosted without borrowing the power of the data symbol, a power difference may occur between the transmitting OFDMA symbols. In this case, the maximum available power of the power amplifier (PA) is set based on the power of the boosted pilot. Therefore, an expensive PA having a relatively wide power range may be used, or a problem may occur in that the PA has low power efficiency.

Therefore, in order to avoid power inequality between OFDM symbols, it is desirable to adjust the power level for each symbol by borrowing the power of the data area or having the same number of pilots for each OFDMA symbol.

In embodiments of the present invention, the pilot allocation structure may be applied regardless of uplink and downlink. In addition, the pilot allocation structure may be used only as a common pilot and may be used only as a dedicated pilot. In addition, the pilot structure may be used together as a common pilot and a dedicated pilot.

In a pilot structure disclosed in embodiments of the present invention, a signal such as a control channel or a preamble may be carried. In this case, the pilot may not be loaded only at the position where the control channel or the preamble is allocated. In addition, a dedicated pilot used only for a location to which a control channel or preamble is allocated may be allocated. Embodiments of the present invention can also be applied to a pilot allocation structure of multicast and broadcast service (MBS) data transmission.

The pilot allocation structure used in the above-described embodiments of the present invention will be represented by one resource block (RB) unit and tile (small resource unit constituting the RB) and used in units of a distributed allocation method. Can be. In this case, the vertical axis may be represented by a subcarrier index as a frequency domain and the horizontal axis may be represented by an OFDM symbol index as a time domain.

The pilot allocation structure of the present invention is applied repeatedly in time domain and frequency domain within a frame or subframe. The pilot allocation structure of the present invention may be applied regardless of uplink and downlink, and may be used only as a common pilot, or may be used only as a dedicated pilot, or a common pilot and a designated pilot. Can also be used together. When a signal such as a control channel or a preamble is loaded, the pilot may not be loaded only on the signal, or another pilot dedicated to the signal may be loaded. The present invention can also be applied to a pilot allocation structure of multicast broadcast service (MBS) data transmission.

Although the pilot allocation method of the present invention is represented by the reference unit resource allocation structure, it is not necessary to limit this, and may be applied to other unit resource allocation structures in the same manner. In other words, it is to be understood that an important pilot allocation criterion lies in the pilot spacing of the frequency and time axes.

In the accompanying drawings, the horizontal axis represents a set of time domain OFDM symbols and the vertical axis represents a subcarrier of a frequency domain. The dark shaded part is where the pilot is loaded. A resource element without any indication is a resource element for data transmission. The pilot structure proposed in the present invention is applied repeatedly in all frequency domains and all time domains.

1 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

1 shows a pilot allocation structure with nine sub-carrier spacings on the frequency axis and two OFDM symbol spacings on the time axis. In the embodiment according to FIG. 1, a pilot may be allocated based on a unit resource block including 9 subcarriers and 6 OFDM symbols.

Referring to Figure 1, the pilot is assigned by Equation (1).

I (k) = 9k + 1, for OFDM symbols where s is 0

I (k) = 9k + 4, for OFDM symbols where s is 2

I (k) = 9k + 7, for OFDM symbols where s is 4

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

Hereinafter, the meaning of the equations used in this document will be described in detail.

(1) s is a function of OFDM symbol index. That is, s = [ OFDM symbol index ] mod m is established. Here, 'm' may have an integer value greater than zero. Therefore, s may have an integer value satisfying 0≤s <m.

(2) If the pilot is spaced apart at regular intervals on the frequency axis, I is given as a function of k (ie, I = I (k), where k can have an integer value greater than or equal to zero).

(3) I can be defined only for all or some of the values that s can have. For example, in Equation 1, I is defined only for s = 0, 2, and 4 of integers of 0 to 5, which are values that s can have.

(4) A value of I means a frequency index value to which a pilot is mapped.

(5) I do not have the OFDM symbol, the pilots (the OFDM symbols with s for which I is not defined) with a s value is mapped are not defined.

(6) The pilot pattern is repeated for every 'm' OFDM symbols.

The meaning of Equation 1 will be described in detail below.

In Equation 1, m = 6 and s may have an integer value of any one of 0 to 5.

In addition, I is defined only for s = 0, 2, and 4 of the integers 0-5 which s can have. Thus, no pilot is mapped to OFDM symbols that do not satisfy s = 0, 2, or 4.

In Equation 1, a pilot may be mapped to a subcarrier with subcarrier indexes of 1, 10, 19, ... in an OFDM symbol with s = 0, and the subcarrier index with 4, 13 in an OFDM symbol with s = 2. The pilot may be mapped to a subcarrier of 22, ..., and the pilot may be mapped to a subcarrier of 7, 16, 25, ... in an OFDM symbol of s = 4.

In FIG. 1, a pilot pattern is repeated every six OFDM symbols. According to the embodiment of FIG. 1, the pilot is mapped only to OFDM symbols having even OFDM symbol indices.

2 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

2 shows a pilot allocation structure with six sub-carrier spacings on the frequency axis and three OFDM symbol spacings on the time axis. In the embodiment of FIG. 2, a pilot may be allocated based on a unit resource block including six subcarriers and six OFDM symbols. Referring to Figure 2, the pilot is assigned by equation (2).

I (k) = 6k + 1, for OFDM symbols where s is 0

I (k) = 6k + 4, for OFDM symbols where s is 3

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

The meaning of Equation 2 will be described in detail below.

In Equation 2, m = 6, and s may have an integer value of any one of 0 to 5. In addition, I is defined only for s = 0 and 3 among the integers of 0-5 which s can have. Thus, no pilot is mapped to OFDM symbols that do not satisfy s = 0, or 3.

In Equation 2, a pilot may be mapped to a subcarrier with subcarrier indexes of 1, 7, 13, ... in an OFDM symbol with s = 0, and the subcarrier index with 4, 10 in an OFDM symbol with s = 3. The pilot may be mapped to a subcarrier that is, 16,... In FIG. 2, a pilot pattern is repeated for every six OFDM symbols.

3 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 3 shows a pilot allocation structure with 13 sub-carrier spacings on the frequency axis and 1 OFDM symbol spacing on the time axis. In the embodiment of FIG. 3, a pilot may be allocated based on a unit resource block including 26 subcarriers and two OFDM symbols. Referring to Figure 3, the pilot is assigned by equation (3).

I (k) = 13k + 3, for OFDM symbols where s is 0

I (k) = 13k + 9, for OFDM symbols where s is 1

I: sub-carrier index (k = 0, 1, ...)

s: [OFDM symbol index] mod 2

(OFDM symbol index = 0,1,2, ...)

Equation 3 may be expressed as follows.

I (k) = 13k + 3 at even OFDM symbols

I (k) = 13k + 9 at odd OFDM symbols

I: sub-carrier index (k = 0, 1, ...)

The meaning of Equation 3 will be described in detail below.

In Equation 3, m = 2, and s may have an integer value of any one of 0 to 1. In addition, I is defined for both 0 and 1, which are the values s can have.

In Equation 3, a pilot may be mapped to a subcarrier with subcarrier indexes of 3, 16, 29, ... in an OFDM symbol with s = 0, and the subcarrier index with 9, 22 in an OFDM symbol with s = 1. The pilot may be mapped to a subcarrier that is, 35, .... In FIG. 3, the pilot pattern is repeated for every two OFDM symbols.

4 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

4 shows a pilot allocation structure with six sub-carrier spacings on the frequency axis and two OFDM symbol spacings on the time axis. In the embodiment of FIG. 4, a pilot may be allocated based on a unit resource block including 18 subcarriers and 3 OFDM symbols. Referring to Figure 4, the pilot is assigned by equation (4).

I (k) = 6k + 1, for OFDM symbols where s is 0

I (k) = 6k + 4, for OFDM symbols where s is 2

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 3

(OFDM symbol index = 0,1,2, ...)

The meaning of Equation 4 will be described in detail below.

In Equation 4, m = 3, and s may have an integer value of any one of 0 to 2. In addition, I is defined only for s = 0 and 2 among the integers of 0-2 which s can have. Thus, no pilot is mapped to OFDM symbols that do not satisfy s = 0, or 2.

In Equation 4, a pilot may be mapped to a subcarrier with subcarrier indexes of 1, 7, 13, ... in an OFDM symbol with s = 0, and the subcarrier index with 4, 10 in an OFDM symbol with s = 2. The pilot may be mapped to a subcarrier that is, 16,... In FIG. 4, the pilot pattern is repeated for every three OFDM symbols.

5 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

5 shows a pilot allocation structure with six sub-carrier spacings on the frequency axis. 5 is a pilot structure allocated based on a unit resource block including 18 subcarriers and 6 OFDM symbols. 5 is a structure in which the structure of FIG. 4 is repeated on the time axis. Referring to Figure 5, the pilot is assigned by equation (5).

I (k) = 6k + 1, for OFDM symbols where s is 0 or 3

I (k) = 6k + 4, for OFDM symbols where s is 2 or 5

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

The meaning of Equation 5 will be described in detail below.

In Equation 5, m = 6 and s may have an integer value of any one of 0 to 5. In addition, I is defined only for s = 0, 2, 3, 5 among integers of 0-5, which are values that s can have. Therefore, no pilot is mapped to OFDM symbols that do not satisfy s = 0, 2, 3, or 5.

In Equation 5, a pilot may be mapped to a subcarrier with subcarrier indices of 1, 7, 13, ... in an OFDM symbol with s = 0 or 3, and the subcarrier index in an OFDM symbol with s = 2 or 5 The pilot may be mapped to subcarriers with 4, 10, 16, ... In FIG. 5, a pilot pattern is repeated for every six OFDM symbols.

<Example 1>

6 illustrates a pilot allocation structure according to an embodiment of the present invention.

FIG. 6 illustrates an example in which FIG. 1 is modified and applied with an offset of +1 by one OFDM symbol in the time axis in the structure of FIG. 1. Referring to Figure 6, the pilot is assigned by equation (6).

I (k) = 9k + 1, for OFDM symbols where s is 1

I (k) = 9k + 4, for OFDM symbols where s is 3

I (k) = 9k + 7, for OFDM symbols where s is 5

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

1 is defined when I is s = 0, 2, and 4, but in FIG. 6, the pattern according to FIG. 6 is different from the pattern of FIG. 1 in that it is defined when I is s = 1, 3 and 5. According to the embodiment of FIG. 6, the pilot is mapped only to OFDM symbols having an odd OFDM symbol index.

<Example 2>

7 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 7 illustrates a modified example of FIG. 1 in which the offset of -1 is applied by one subcarrier on the frequency axis and +1 is offset by one OFDM symbol in the time domain. to be. Referring to FIG. 7, the pilot is assigned by equation (7).

I (k) = 9k, for OFDM symbols where s is 1

I (k) = 9k + 3, for OFDM symbols where s is 3

I (k) = 9k + 6, for OFDM symbols where s is 5

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

In FIG. 1, at I (k) = 9k + offset , offset = 1, 4, or 7, but in FIG. 7, offset = 0, 3, or 6, and in FIG. 1, I is s = 0, 2, 4 7 is different from the pattern of FIG. 1 in that I is defined when I is s = 1, 3, and 5. According to the embodiment of FIG. 7, the pilot is mapped only to OFDM symbols having an odd OFDM symbol index.

<Example 3>

8 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 8 is an example in which FIG. 1 is modified and applied with an offset of −1 by one subcarrier on the frequency axis in the structure of FIG. 1. Referring to Figure 8, the pilot is assigned by equation (8).

I (k) = 9k, for OFDM symbols where s is 0

I (k) = 9k + 3, for OFDM symbols where s is 2

I (k) = 9k + 6, for OFDM symbols where s is 4

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

Figure 1 in the I (k) = the in 9k + offset in terms of offset = 1, 4, or 7, but in Figure 8 offset = 0, 3, or 6, the pattern according to Figure 8 differs from the pattern of the Fig. According to the embodiment of FIG. 8, the pilot is mapped only to OFDM symbols having an even OFDM symbol index.

<Example 4>

9 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 9 illustrates an example in which FIG. 2 is modified and applied with an OFDM symbol offset of +1 in the time domain in the structure of FIG. 2. Referring to Figure 9, the pilot is assigned by equation (9).

I (k) = 6k + 1, for OFDM symbols where s is 1

I (k) = 6k + 4, for OFDM symbols where s is 4

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

In FIG. 2, the pattern according to FIG. 9 is different from the pattern according to FIG. 2 in that I is defined when I is s = 0 and 3, but is defined when I is s = 1 and 4 in FIG. 9.

<Example 4-1>

10 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 10 is a modified example of FIG. 2, in which the OFDM symbol offset of +2 is applied to the time domain in the structure of FIG. 2. Referring to FIG. 10, the pilot is assigned by equation (10).

I (k) = 6k + 1, for OFDM symbols where s is 2

I (k) = 6k + 4, for OFDM symbols where s is 5

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

In FIG. 2, the pattern according to FIG. 10 is different from the pattern according to FIG. 2 in that I is defined when I is s = 0 and 3, but is defined when I is s = 2 and 5 in FIG. 10.

<Example 5>

11 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 11 illustrates an example in which FIG. 2 is modified, in which the OFDM symbol offset of +1 is given to the time domain in the structure of FIG. 2 and the subcarrier offset of -1 is applied to the frequency domain. Referring to Figure 11, the pilot is assigned by equation (11).

I (k) = 6k, for OFDM symbols where s is 1

I (k) = 6k + 3, for OFDM symbols where s is 4

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

In FIG. 2, I is defined when s = 0 and 3, but in FIG. 11, I is defined when s = 1 and 4, and also in FIG. 2, offset = 1 or 4 at I (k) = 6k + offset . In FIG. 11, the pattern according to FIG. 11 is different from the pattern according to FIG. 2 in that offset = 0 or 3.

<Example 5-1>

12 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 12 is a modified example of FIG. 2, in which the OFDM symbol offset of +2 is given to the time domain in the structure of FIG. 2 and the subcarrier offset of -1 is applied to the frequency domain. Referring to Figure 12, the pilot is assigned by equation (12).

I (k) = 6k, for OFDM symbols where s is 2

I (k) = 6k + 3, for OFDM symbols where s is 5

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

In FIG. 2, I is defined when s = 0 and 3, but in FIG. 12, I is defined when s = 2 and 5, and also in FIG. 2, offset = 1 or 4 at I (k) = 6k + offset . In FIG. 12, the pattern of FIG. 12 is different from the pattern of FIG. 2 in that offset = 0 or 3.

<Example 6>

13 illustrates a pilot allocation structure according to an embodiment of the present invention.

FIG. 13 shows a pilot assignment structure with three sub-carrier spacings on the frequency axis and three OFDM symbol spacings on the time axis. 13 is a pilot structure allocated based on a unit resource block including 18 subcarriers and 6 OFDM symbols. Referring to FIG. 13, a pilot is assigned by equation (13).

I (k) = 3k, for OFDM symbols where s is 1

I (k) = 3k + 2, for OFDM symbols where s is 4

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

Equation 13 may be understood in the same manner as Equation 1 to Equation 5 described above. In FIG. 13, a pilot pattern is repeated for every six OFDM symbols.

<Example 6-1>

14 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 14 is a modified example of FIG. 13, in which the subcarrier offset of +2 is cyclically applied to the frequency domain in the structure of FIG. 13.

Referring to Figure 14, the pilot is assigned by equation (14).

I (k) = 3k + 2, for OFDM symbols where s is 1

I (k) = 3k, for OFDM symbols where s is 4

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

In FIG. 13, I (k) = 3k is defined for an OFDM symbol with s = 1 and I (k) = 3k + 2 for an OFDM symbol with s = 4. The pattern according to FIG. 14 differs from the pattern according to FIG. 13 in that I (k) = 3k + 2 is defined and I (k) = 3k for an OFDM symbol with s = 4.

<Example 7>

15 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 15 shows a pilot assignment structure with four sub-carrier spacings on the frequency axis and three OFDM symbol spacings on the time axis. The embodiment according to FIG. 15 is a pilot structure allocated based on a unit resource block consisting of 12 subcarriers and 6 OFDM symbols. Referring to Figure 15, the pilot is assigned by equation (15).

I (k) = 4k, for OFDM symbols where s is 1

I (k) = 4k + 2, for OFDM symbols where s is 4

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

Equation 15 may be understood in the same manner as Equation 1 to Equation 5 described above. In FIG. 15, a pilot pattern is repeated for every six OFDM symbols.

<Example 8>

16 illustrates a pilot allocation structure according to an embodiment of the present invention.

FIG. 16 is a modified example of FIG. 15, in which the subcarrier offset of +1 is applied to the frequency domain in the structure of FIG. 15. Referring to Figure 16, the pilot is assigned by equation (16).

I (k) = 4k + 1, for OFDM symbols where s is 1

I (k) = 4k + 3, for OFDM symbols where s is 4

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

In FIG. 15, the offset according to FIG. 16 differs from the pattern illustrated in FIG. 15 in that offset = 0 or 2 at I (k) = 4k + offset , but offset = 1 or 3 in FIG. 16.

Example 9

17 illustrates a pilot assignment structure according to an embodiment of the present invention.

FIG. 17 is a pilot structure applicable when a granularity of a tile in a frequency domain is a multiple of 4, wherein the horizontal axis represents a time domain of OFDM symbols, and the vertical axis represents a frequency domain of subcarriers Indicates.

17 shows a structure consisting of 12 subcarriers and 6 OFDM symbols. This may of course also be applied to other resource block unit structures consisting of multiples of four, such as 24 subcarriers, in addition to 12 subcarriers. 17 shows an example in which a basic tile composed of four subcarriers and six OFDM symbols is repeated three times on the frequency axis.

First, a rule in which pilots are allocated in one basic tile will be described.

The part bolded in the upper part of FIG. 17 represents one basic tile composed of four subcarriers and six OFDM symbols. In order to improve the performance of the edge sub-carriers, the pilots are concentrated on the edges of the base tiles. In FIG. 17, four pilots are allocated to the first OFDM symbol and the last OFDM symbol of the edge subcarrier of the base tile. The pilot structure assigned to the base tile is extended in the frequency domain and the time domain, and can be equally applied to all the other tiles. Depending on the permutation mode and the permutation method, the location of each tile can be assigned adjacent to each other or can be spread.

I (k) = 3k, for OFDM symbols where s is 0 or 5

I: sub-carrier index (k = 0, 1),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

The meaning of Equation 17 is described in detail below.

In Equation 17, m = 6 and s may have an integer value of any one of 0 to 5. In addition, I is defined only for s = 0 and 5 among the integers of 0-5 which s can have. Thus, no pilot is mapped to OFDM symbols that do not satisfy s = 0, 5. In Equation 17, pilots are mapped to subcarriers with subcarrier indexes 0 and 3 in OFDM symbols s = 0, 5. In FIG. 17, the pilot pattern is repeated every three OFDM symbols on the time axis and every four subcarriers on the frequency axis.

Equation 17 is an equation representing a position of a pilot allocated to one basic tile, and may be understood in the same manner as in Equations 1 to 5 described above. In FIG. 17, the pilot pattern is repeated every six OFDM symbols on the time axis, and the pilot pattern is repeated every four subcarriers on the frequency axis.

One basic tile has been described above, and the mapping method in consideration of the entirety of FIG. 17 will now be described. Considering the entire FIG. 17, Equation 17 may be expressed as Equation 17-1.

[Equation 17-1]

I = 0, 3, 4, 7, 8, 11 for OFDM symbols where s is 0 or 5

I: sub-carrier index,

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

According to FIG. 17, the pilot pattern in one unit of a resource block can be used repeatedly in the same manner in all remaining subframes and frames.

<Example 10>

18 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 18 is a pilot structure applicable when a granularity of a tile in a frequency domain is a multiple of 4, wherein the horizontal axis represents a time domain composed of OFDM symbols, and the vertical axis represents a frequency domain composed of subcarriers Indicates.

18 shows a structure consisting of 12 subcarriers and 6 OFDM symbols. 18 shows a form in which a basic tile composed of four subcarriers and six OFDM symbols is repeated three times on the frequency axis.

First, a rule in which pilots are allocated in one basic tile will be described.

The part bolded in the upper part of FIG. 18 represents one basic tile composed of four subcarriers and six OFDM symbols. The pilot is allocated only to the edge subcarrier portion of the second and fifth OFDM symbols of the base tile. That is, a total of four pilots are allocated to one basic tile. The pilot structure assigned to the base tile is extended in the frequency domain and the time domain, and can be equally applied to all the other tiles. Depending on the permutation mode and the permutation method, the location of each tile can be assigned adjacent to each other or can be spread.

Referring to FIG. 18, a pilot in one basic tile is assigned by the equation (17).

I (k) = 3k, for OFDM symbols where s is 1 or 4

I: sub-carrier index (k = 0, 1),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

The meaning of Equation 18 is described in detail below.

In Equation 18, m = 6 and s may have an integer value of any one of 0 to 5. In addition, I is defined only for s = 1, 4 among the integers of 0-5 which s can have. Thus, no pilot is mapped to OFDM symbols that do not satisfy s = 1, 4. In Equation 18, pilots are mapped to subcarriers with subcarrier indexes 0 and 3 in OFDM symbols s = 1, 4. In FIG. 18, a pilot pattern is repeated for every six OFDM symbols.

Equation 18 is an equation representing a position of a pilot allocated to one basic tile and may be understood in the same manner as in Equation 1 to Equation 5 described above. In FIG. 18, if the pilot pattern is repeated every six OFDM symbols on the time axis, the pilot pattern is repeated every four subcarriers on the frequency axis.

One basic tile has been described above, and the mapping method considering the entire FIG. 18 will now be described. Considering the entire FIG. 18, Equation 18 may be expressed as Equation 18-1.

Equation 18-1

I = 0, 3, 4, 7, 8, 11 for OFDM symbols where s is 1 or 4

I: sub-carrier index,

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

Referring to FIG. 18, a pilot pattern in one unit of a resource block can be used in the same manner in all remaining subframes and frames.

<Example 11>

19 illustrates a pilot allocation structure according to an embodiment of the present invention.

19 is a pilot structure applicable when the granularity of a tile in a frequency domain is a multiple of 4, the horizontal axis showing a time domain of OFDM symbols, and the vertical axis of a frequency domain of subcarriers Indicates.

19 shows a structure consisting of 12 subcarriers and 6 OFDM symbols. 19 shows a form in which a basic tile composed of four subcarriers and six OFDM symbols is repeated three times on the frequency axis.

First, a rule in which pilots are allocated in one basic tile will be described.

The part bolded in the upper part of FIG. 19 represents one basic tile composed of four subcarriers and six OFDM symbols. Four pilots are allocated to the first and last OFDM symbols of the second and third subcarriers of the base tile. The pilot structure assigned to the base tile is extended in the frequency domain and the time domain, and can be equally applied to all the other tiles. Depending on the permutation mode and the permutation method, the location of each tile can be assigned adjacent to each other or can be spread.

Referring to FIG. 19, a pilot in one basic tile is assigned by the equation (19).

I (k) = 1 and 2, for OFDM symbols where s is 0 or 5

I: sub-carrier index,

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

Equation 19 is an equation representing a position of a pilot allocated to one basic tile, and may be understood in the same manner as in Equations 1 to 5 described above. In FIG. 19, the pilot pattern is repeated every six OFDM symbols on the time axis, and the pilot pattern is repeated every four subcarriers on the frequency axis.

One basic tile has been described above, and the whole of FIG. 19 may be described similarly to the description of FIG. 17.

<Example 12>

20 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 20 is a modified example of FIG. 18, and a location where a pilot is allocated in one basic tile is different from FIG. 18. Other characteristics of the embodiment according to FIG. 20 are similar to those in FIG. 18.

Referring to FIG. 20, a pilot is allocated by Equation 20 in one basic tile.

I (k) = 1 and 2, for OFDM symbols where s is 1, 4

I: sub-carrier index

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

Example 13

21 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 21 shows a pilot allocation structure with nine sub-carrier spacings on the frequency axis and one OFDM symbol spacing on the time axis. 21 illustrates a pilot structure allocated based on a unit resource block including 18 subcarriers and 3 OFDM symbols.

Referring to FIG. 21, a pilot is assigned by Equation 21.

I (k) = 6k, for OFDM symbols where s is 0

I (k) = 6k + 9, for OFDM symbols where s is 2

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 3

(OFDM symbol index = 0,1,2, ...)

Equation 21 may be interpreted in the same manner as the equations according to the above-described embodiment. In addition, the pilot pattern in a resource block of one unit can be used repeatedly in the same manner in all remaining subframes and frames.

<Example 14>

22 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

22 shows a pilot allocation structure with one OFDM symbol spacing on the time axis. The embodiment according to FIG. 22 is a pilot structure allocated based on a unit resource block consisting of 26 subcarriers and two OFDM symbols.

Referring to Figure 22, the pilot is assigned by equation (22).

I = 8 and 17, for OFDM symbols where s is 0

I = 0 and 25, for OFDM symbols where s is 1

I: sub-carrier index,

s: [OFDM symbol index] mod 2

(OFDM symbol index = 0,1,2, ...)

Equation 22 may be interpreted in the same manner as the equations according to the above-described embodiment. In addition, the pilot pattern in a resource block of one unit can be used repeatedly in the same manner in all remaining subframes and frames.

<Example 15>

23 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 23 is a modified example of FIG. 22. Referring to Figure 23, the pilot is assigned by equation (23).

I = 0 and 25, for OFDM symbols where s is 0

I = 8 and 17, for OFDM symbols where s is 1

I: sub-carrier index,

s: [OFDM symbol index] mod 2

(OFDM symbol index = 0,1,2, ...)

<Example 16>

24 illustrates a pilot allocation structure according to an embodiment of the present invention.

The embodiment according to FIG. 24 is a pilot structure allocated based on a unit resource block including 9 subcarriers and 6 OFDM symbols.

In FIG. 24, in a unit resource block consisting of 9 subcarriers and 6 OFDM symbols, a pilot is allocated to one subcarrier for each OFDM symbol, and the index of the subcarrier to which the pilot is allocated is constant as the OFDM symbol index increases. Shifted to size

Figure 24 (a) shows a pilot allocation structure with one OFDM symbol spacing on the time axis. Referring to Figure 24 (a), the pilot is assigned by equation (24).

I = 0, for OFDM symbols where s is 0, 3

I = 4, for OFDM symbols where s is 1, 4

I = 8, for OFDM symbols where s is 2, 5

I: sub-carrier index,

s: [OFDM symbol index] mod 2

(OFDM symbol index = 0,1,2, ...)

(B), (c), (d) of FIG. 24 is an example in which (a) of FIG. 24 is modified. FIG. 24 (b) shows a pilot allocation structure having three subcarrier spacings on the frequency axis and one OFDM symbol spacing on the time axis. 24 (c) and (d) show a pilot allocation structure having one OFDM symbol spacing on the time axis.

In FIG. 24 (b), (c), and (d), the pilots are allocated by Equations 24-1, Equations 24-2, and Equations 24-3, respectively.

[Equation 24-1]

I = 1, for OFDM symbols where s is 0, 3

I = 4, for OFDM symbols where s is 1, 4

I = 7, for OFDM symbols where s is 2, 5

I: sub-carrier index,

s: [OFDM symbol index] mod 2

(OFDM symbol index = 0,1,2, ...)

[Equation 24-2]

I = 2, for OFDM symbols where s is 0, 3

I = 4, for OFDM symbols where s is 1, 4

I = 6, for OFDM symbols where s is 2, 5

I: sub-carrier index,

s: [OFDM symbol index] mod 2

(OFDM symbol index = 0,1,2, ...)

[Equation 24-3]

I = 3, for OFDM symbols where s is 0, 3

I = 4, for OFDM symbols where s is 1, 4

I = 5, for OFDM symbols where s is 2, 5

I: sub-carrier index,

s: [OFDM symbol index] mod 2

(OFDM symbol index = 0,1,2, ...)

In FIG. 24, a pilot pattern in one unit of a resource block may be used in the same manner in all the remaining subframes and frames.

<Example 17>

25 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

The pilot pattern shown in FIG. 25 is the second and fifth OFDM symbols in a unit resource block composed of three OFDM symbol spacings on the time axis, that is, every symbol having an OFDM symbol index of 1 and 4 The pilot is allocated adjacent to all subcarriers. 25 shows a pilot structure allocated based on a unit resource block including 12 subcarriers and 6 OFDM symbols.

In FIG. 25, a pilot pattern in one unit of a resource block may be used in the same manner in all the remaining subframes and frames.

Example 18

26 illustrates a pilot allocation structure according to an embodiment of the present invention.

The pilot pattern shown in FIG. 26 has a 2, 5, 8, 11th OFDM symbol, that is, an OFDM symbol index of 1, 4, 7 in a unit resource block composed of 3 OFDM symbol spacings on the time axis. For each symbol, 10, the pilot is allocated contiguously to all subcarriers of that symbol. The embodiment according to FIG. 26 is a pilot structure allocated based on a unit resource block consisting of 12 subcarriers and 12 OFDM symbols.

In FIG. 26, a pilot pattern in one unit of a resource block may be used in the same manner in all the other subframes and frames.

Example 19

27 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

27 shows a pilot allocation structure with three OFDM symbol spacings on the time axis. The embodiment according to FIG. 27 is a pilot structure allocated on the basis of a unit resource block including 9 subcarriers and 12 OFDM symbols.

Referring to Figure 27, the pilot is assigned by equation (25).

I (k) = 4k, for OFDM symbols where s is 1, 4, 7, 10

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 12

(OFDM symbol index = 0,1,2, ...)

Equation 25 may be interpreted in the same manner as the equations according to the above-described embodiment. In addition, the pilot pattern in one unit of a resource block can be used repeatedly in the same way in all the remaining subframes and frames.

Example 20

28 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

28 shows a pilot allocation structure with one OFDM symbol spacing on the time axis. The embodiment shown in FIG. 28 is a pilot structure allocated on the basis of a unit resource block including 9 subcarriers and 12 OFDM symbols. In FIG. 27, in a unit resource block consisting of 9 subcarriers and 12 OFDM symbols, a pilot is allocated to one subcarrier for each OFDM symbol, and the index of the subcarrier to which the pilot is allocated is constant as the OFDM symbol index increases. Shifted to size

Referring to Figure 28, the pilot is assigned by equation (26).

I = 0, for OFDM symbols where s is 0, 3, 6, 9

I = 4, for OFDM symbols where s is 1, 4, 7, 10

I = 8, for OFDM symbols where s is 2, 5, 8, 11

I: sub-carrier index,

s: [OFDM symbol index] mod 12

(OFDM symbol index = 0,1,2, ...)

Equation 26 may be interpreted in the same manner as the equations according to the above-described embodiment. In addition, the pilot pattern in one unit of a resource block can be used repeatedly in the same way in all the remaining subframes and frames.

Example 21

29 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 29 is a modified embodiment of FIG. 28. 29 shows a pilot allocation structure with three subcarrier spacings on the frequency axis and one OFDM symbol spacing on the time axis. 29 illustrates a pilot structure allocated based on a unit resource block including 9 subcarriers and 12 OFDM symbols.

Referring to FIG. 29, the pilot is assigned by equation (27).

I = 1, for OFDM symbols where s is 0, 3, 6, 9

I = 4, for OFDM symbols where s is 1, 4, 7, 10

I = 7, for OFDM symbols where s is 2, 5, 8, 11

I: sub-carrier index,

s: [OFDM symbol index] mod 12

(OFDM symbol index = 0,1,2, ...)

<Example 22>

30 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

30 shows a pilot allocation structure with three OFDM symbol spacings on the time axis. Referring to FIG. 30, the pilot is assigned by equation (28). The embodiment according to FIG. 30 is a pilot structure allocated based on a unit resource block consisting of 9 subcarriers and 6 OFDM symbols. Referring to FIG. 30, the pilot is assigned by equation (28).

I (k) = 4k, for OFDM symbols where s is 1, 4

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

According to the structure of FIG. 30, since the pilot is allocated only to the 2nd and 5th OFDM symbols on the time axis, appropriate performance can be obtained against time varying compared to the pilot overhead. In FIG. 30, the pilot pattern in one unit of a resource block may be used in the same manner in all remaining subframes and frames.

<Example 23>

31 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

31 shows a pilot allocation structure with one OFDM symbol spacing on the time axis. 31 shows a pilot structure allocated based on a unit resource block including 9 subcarriers and 6 OFDM symbols. Referring to Figure 31, the pilot is assigned by equation (29).

I = 0, for OFDM symbols where s is 0, 1

I = 4, for OFDM symbols where s is 2, 3

I = 8, for OFDM symbols where s is 4, 5

I: sub-carrier index,

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

In Figure 31, to minimize power fluctuations per OFDM symbol, a pilot is allocated for each OFDM symbol, and the pilot is shifted and allocated with a constant frequency offset every two OFDM symbols. In FIG. 31, a pilot pattern in one unit of a resource block may be used in the same manner in all remaining subframes and frames.

<Example 24>

32 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

32 is a modified example of FIG. In FIG. 32, the frequency offset value of the pilot allocation start point is set to +1. The offset value may have a value other than +1.

Referring to FIG. 32, a pilot is assigned by equation (30).

I = 1, for OFDM symbols where s is 0, 1

I = 4, for OFDM symbols where s is 2, 3

I = 7, for OFDM symbols where s is 4, 5

I: sub-carrier index,

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

<Example 25>

33 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

33 shows a pilot allocation structure with nine subcarrier spacings on the frequency axis and one OFDM symbol spacing on the time axis. The embodiment according to FIG. 33 is a pilot structure allocated based on a unit resource block composed of 18 subcarriers and 6 OFDM symbols. Referring to FIG. 33, the pilot is assigned by Equation 31.

I (k) = 9k + 1, for OFDM symbols where s is 0, 3

I (k) = 9k + 4, for OFDM symbols where s is 1, 4

I (k) = 9k + 7, for OFDM symbols where s is 2, 5

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

Equation 31 may be interpreted in the same manner as the equations according to the above-described embodiment. In FIG. 33, the pilot pattern in one unit of a resource block may be used in the same manner in all the remaining subframes and frames.

Example 26

34 illustrates a pilot allocation structure according to an embodiment of the present invention.

34 is an example in which FIG. 33 is modified. Referring to Figure 34, the pilot is assigned by equation (32).

I (k) = 9k, for OFDM symbols where s is 0, 3

I (k) = 9k + 4, for OFDM symbols where s is 1, 4

I (k) = 9k + 8, for OFDM symbols where s is 2, 5

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

Example 27

35 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 35 shows a pilot allocation structure with three sub-carrier spacings on the frequency axis and one OFDM symbol spacing on the time axis. 35 shows a pilot structure allocated based on a unit resource block consisting of 12 subcarriers and 6 OFDM symbols.

Referring to FIG. 35, a pilot is assigned by equation (33).

I (k) = 3k, for OFDM symbols where s is 0, 3

I (k) = 3k + 1, for OFDM symbols where s is 1, 4

I (k) = 3k + 2, for OFDM symbols where s is 2, 5

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

Equation 33 may be interpreted in the same manner as the equations according to the above-described embodiment. In FIG. 35, the pilot pattern in one unit of a resource block may be used in the same manner in all remaining subframes and frames.

<Example 28>

36 illustrates a pilot allocation structure according to an embodiment of the present invention.

36 shows a pilot allocation structure with three subcarrier spacings on the frequency axis and one OFDM symbol spacing on the time axis. 36 illustrates a pilot structure allocated based on a unit resource block including 6 subcarriers and 12 OFDM symbols. Referring to FIG. 36, a pilot is assigned by equation (34).

I (k) = 3k, for OFDM symbols where s is 0, 3, 6, 9

I (k) = 3k + 1, for OFDM symbols where s is 1, 4, 7, 10

I (k) = 3k + 2, for OFDM symbols where s is 2, 5, 8, 11

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 12

(OFDM symbol index = 0,1,2, ...)

Equation 34 may be interpreted in the same manner as the equations according to the above-described embodiment. In FIG. 36, a pilot pattern in one unit of a resource block may be used in the same manner in all remaining subframes and frames.

<Example 29>

37 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 37 shows a pilot allocation structure with one sub-carrier spacing on the frequency axis and three OFDM symbol spacings on the time axis. The embodiment of FIG. 37 is a pilot structure allocated based on a unit resource block consisting of six subcarriers and 12 OFDM symbols.

In FIG. 37, a pilot is allocated to every 2nd, 5th, 8th, and 11th OFDM symbols. That is, a pilot is allocated to each OFDM symbol having index numbers 1, 4, 7, and 10. The offset of the OFDM symbol at which pilot allocation starts is +1.

In FIG. 37, a pilot pattern in one unit of a resource block may be used in the same manner in all the remaining subframes and frames.

<Example 30>

38 illustrates a pilot allocation structure according to an embodiment of the present invention.

FIG. 38 illustrates the embodiment of FIG. 35 based on a unit resource allocation structure consisting of 12 subcarriers and 12 OFDM symbols. Referring to FIG. 38, a pilot is assigned by equation (35).

I (k) = 3k, for OFDM symbols where s is 0, 3, 6, 9

I (k) = 3k + 1, for OFDM symbols where s is 1, 4, 7, 10

I (k) = 3k + 2, for OFDM symbols where s is 2, 5, 8, 11

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 12

(OFDM symbol index = 0,1,2, ...)

<Example 31>

39 illustrates a pilot allocation structure according to an embodiment of the present invention.

FIG. 39 illustrates the embodiment of FIG. 37 using a unit resource allocation structure consisting of 12 subcarriers and 12 OFDM symbols.

<Example 32>

40 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

40 shows a pilot allocation structure with six sub-carrier spacings on the frequency axis and three OFDM symbol spacings on the time axis. The embodiment according to FIG. 40 is a pilot structure allocated based on a unit resource block consisting of 12 subcarriers and 6 OFDM symbols.

Referring to Figure 40, the pilot is assigned by equation (36).

I (k) = 6k + 1, for OFDM symbols where s is 1

I (k) = 6k + 4, for OFDM symbols where s is 4

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

<Example 32-1>

41 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 41 illustrates an example in which FIG. 40 is modified and applied with an offset of +1 by one OFDM symbol in the time domain in the structure of FIG. 40. Referring to Fig. 41, the pilot is assigned by equation (37).

I (k) = 6k + 1, for OFDM symbols where s is 2

I (k) = 6k + 4, for OFDM symbols where s is 5

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

<Example 33>

42 illustrates a pilot allocation structure according to an embodiment of the present invention.

42 shows a pilot allocation structure with six sub-carrier spacings on the frequency axis and three OFDM symbol spacings on the time axis. The embodiment according to FIG. 42 is a pilot structure allocated based on a unit resource block consisting of 12 subcarriers and 6 OFDM symbols.

Referring to Figure 42, the pilot is assigned by equation (38).

I (k) = 6k, for OFDM symbols where s is 1

I (k) = 6k + 3, for OFDM symbols where s is 4

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

<Example 33-1>

43 is a diagram illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 43 is a modified example of the case in which an offset of +1 is applied by one OFDM symbol to the time domain in the structure of FIG. 42. Referring to Figure 43, the pilot is assigned by equation (39).

I (k) = 6k, for OFDM symbols where s is 2

I (k) = 6k + 3, for OFDM symbols where s is 5

I: sub-carrier index (k = 0, 1, ...),

s: [OFDM symbol index] mod 6

(OFDM symbol index = 0,1,2, ...)

In order to describe the embodiments of the present invention in detail, the accompanying drawings may be modified in various forms. For example, in the pilot symbol structure in which the technical idea of the present invention is reflected, the drawings are not created by reflecting the cyclic shift for all the drawings. However, the combination of the technical ideas shown in the above drawings can confirm the number of all cases.

That is, the present disclosure discloses pilot symbol structures capable of cyclically shifting pilot symbols included in each pilot symbol structure as one or more OFDM symbol units and / or one or more subcarrier units.

In embodiments of the present invention, the base station has a predefined phase shift codeset, and uses the same to distinguish pilots (or channel information estimated through the same) allocated to the same location.

The invention can be embodied in other specific forms without departing from the spirit and essential features of the invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention. In addition, the claims may be combined with claims that do not have an explicit citation relationship in the claims, or may be incorporated into new claims by revision after application.

The present invention can be used for a terminal or a network device used in a wireless access system.

1 to 43 are diagrams illustrating a pilot allocation structure according to an embodiment of the present invention.

FIG. 44 shows an example of a general pilot structure used in the eye single transmit antenna structure. FIG.

Claims (15)

In the method of transmitting and receiving data in a wireless access system, Transmitting data using a resource block configured in consideration of channel estimation performance and data rate; And Receiving data using the resource block Including, The resource block includes pilot symbols comprising a predetermined number and a predetermined pattern. The method of claim 1, The resource block has a subcarrier and OFDM symbol configuration of 4 × 6, the data transmission and reception method. The method of claim 2, And a pilot is allocated only to the first OFDM symbol and the sixth OFDM symbol of the first subcarrier and the fourth subcarrier of the RB. The method of claim 2, And a pilot is allocated only to a first OFDM symbol and a sixth OFDM symbol of a second subcarrier and a third subcarrier of the RB. The method of claim 1, The resource block has a subcarrier and OFDM symbol configuration of 4 × 6, the data transmission and reception method. The method of claim 5, And a pilot is allocated only to a second OFDM symbol and a fifth OFDM symbol of a first subcarrier and a fourth subcarrier of the RB. The method of claim 5, And a pilot is allocated only to a second OFDM symbol and a fifth OFDM symbol of the second subcarrier and the third subcarrier of the RB. The method of claim 1, A pilot is allocated at intervals of one OFDM symbol on the time axis. The method of claim 8, A pilot is allocated in three, nine, or thirteen subcarrier intervals on the frequency axis. The method of claim 1, A pilot is allocated at intervals of two OFDM symbols on a time axis. The method of claim 10, A pilot is allocated in six or nine subcarrier intervals along the frequency axis. The method of claim 1, A pilot is allocated at intervals of three OFDM symbols on a time axis. The method of claim 12, A pilot is allocated in one, three, four, or six subcarrier intervals on the frequency axis. The method of claim 1, A method of transmitting and receiving data, wherein pilots are allocated at intervals of six subcarriers along the frequency axis. The method of claim 1, The resource block has 4 × 6, 6 × 6, 6 × 12, 9 × 6, 9 × 12, 12 × 6, 12 × 12, 13 × 2, 18 × 3, and 18 × subcarrier and OFDM symbol configurations. 6, 24 × 6, and 26 × 2.

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