WO2010123250A2

WO2010123250A2 - Communication method and apparatus for a multi-carrier environment

Info

Publication number: WO2010123250A2
Application number: PCT/KR2010/002451
Authority: WO
Inventors: 문성호; 조한규; 곽진삼
Original assignee: 엘지전자 주식회사
Priority date: 2009-04-20
Filing date: 2010-04-20
Publication date: 2010-10-28
Also published as: WO2010123250A3

Abstract

The present invention relates to a wireless communication system. More particularly, the present invention relates to a method and to an apparatus for performing a downlink transmission in an OFDMA system which supports multiple carriers, wherein said method comprises: the steps of generating a plurality of symbols of a subframe; and transmitting a plurality of subframes by selectively using a first frame structure or a second frame structure, wherein said first frame structure includes a plurality of a first type of subframe arranged in series, and one or more of a second type of subframe following the subframes of the first type, and said second frame structure includes said plurality of subframes of the first type and said one or more subframes of the second type, and at least one subframe of the second type is interposed between the plurality of subframes of the first type. The present invention also relates to an apparatus for the method.

Description

Method and apparatus for communication in multi-carrier situation

The present invention relates to a wireless communication system. In particular, the present invention relates to a method and apparatus for performing communication in a multi-carrier situation.

1 illustrates a wireless communication system. Wireless communication systems are widely deployed to provide various kinds of communication services such as voice and data.

Referring to FIG. 1, the wireless communication system 100 includes a plurality of base stations 110 and a plurality of terminals 120. The wireless communication system 100 may include a homogeneous network or a heterogeneous network. Here, the heterogeneous network refers to a network in which different network entities coexist such as a macro cell, a femto cell, a pico cell, a repeater, and the like. A base station is generally a fixed station that communicates with a terminal, and each

base station

110a, 110b, and 110c provides services to specific

geographic regions

102a, 102b, and 102c. In order to improve system performance, the particular area may be divided into a plurality of

smaller areas

104a, 104b and 104c. Each smaller area may be referred to as a cell, sector or segment. The terminal 120 is generally distributed in a wireless communication system and can be fixed or mobile. Each terminal may communicate with one or more base stations via uplink (UL) and downlink (DL) at any instant. The base station and the terminal are frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), single carrier-FDMA (SC-FDMA), multi carrier-FDMA (MC-FDMA), and OFDMA ( Communication may be performed using Orthogonal Frequency Division Multiple Access) or a combination thereof. In the present specification, uplink refers to a communication link from a terminal to a base station, and downlink refers to a communication link from a base station to a terminal.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for efficiently performing communication in a wireless communication system supporting multi-carriers. Another object of the present invention is to provide a method and apparatus therefor for subframe alignment between frames in case of supporting legacy terminals in an adjacent carrier.

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the following description. Could be.

In an aspect of the present invention, a method for performing downlink transmission by a base station in an orthogonal frequency division multiple access (OFDMA) system supporting a multi carrier (MC), generating a plurality of symbols included in a subframe Making; And selectively transmitting a plurality of subframes to the terminal using a first frame structure (FS) or a second frame structure, wherein the first frame structure comprises a plurality of consecutive first type subframes. And thereafter one or more second type subframes, wherein the second frame structure includes the plurality of first type subframes and the one or more second type subframes, and at least one second type subframe. Is provided a method for performing downlink transmission located between the plurality of first type subframes.

In another aspect of the present invention, a base station of an orthogonal frequency division multiple access (OFDMA) system supporting a multi-carrier (Multi Carrier), comprising: a radio frequency (RF) unit configured to transmit and receive a radio signal with a terminal; A memory for storing information transmitted and received with the terminal and parameters necessary for the operation of the base station; And a processor coupled to the RF unit and the memory, the processor configured to control the RF unit and the memory, the processor generating a plurality of symbols included in a subframe; And selectively transmitting a plurality of subframes to the terminal by using a first frame structure or a second frame structure, wherein the first frame structure includes a plurality of consecutive first type subframes and one thereafter. And a second type subframe, wherein the second frame structure includes the plurality of first type subframes and the one or more second type subframes, wherein at least one second type subframe includes the plurality of second type subframes. A base station configured to perform a downlink signal transmission method located between one type subframes is provided.

According to another aspect of the present invention, a method for processing a downlink signal by a terminal in an orthogonal frequency division multiple access (OFDMA) system supporting a multi-carrier, the method comprising: receiving a plurality of symbols from a base station; Optionally using a first frame structure or a second frame structure to process the plurality of symbols in subframe units, wherein the first frame structure comprises a plurality of consecutive first type subframes and subsequent One or more second type subframes, wherein the second frame structure includes the plurality of first type subframes and the one or more second type subframes, wherein at least one second type subframe includes: A downlink signal processing method located between first type subframes is provided.

According to another aspect of the present invention, a terminal of an orthogonal frequency division multiple access (OFDMA) system supporting a multi-carrier includes: a radio frequency (RF) unit configured to transmit and receive a radio signal with a base station; A memory for storing information transmitted and received with the base station and parameters necessary for the operation of the terminal; And a processor coupled to the RF unit and the memory, the processor configured to control the RF unit and the memory, the processor receiving a plurality of symbols from the base station; Optionally using a first frame structure or a second frame structure to process the plurality of symbols in subframe units, wherein the first frame structure comprises a plurality of consecutive first type subframes and subsequent One or more second type subframes, wherein the second frame structure includes the plurality of first type subframes and the one or more second type subframes, wherein at least one second type subframe includes: A terminal configured to perform a downlink signal processing method located between first type subframes is provided.

Preferably, the first frame structure and the second frame structure may each include a first downlink structure and a second downlink structure described in the following table:

Here, SF represents a subframe index, each number represents the number of symbols included in the subframe, any one of X ₁ to X ₃ is 5 and the other two represents 6. In this case, X ₁ may be 5, and X ₂ and X ₃ may be 6.

Preferably, the second frame structure may be used for a first carrier, and a legacy support frame structure may be used for a second carrier adjacent to the first carrier. In this case, the legacy support frame structure includes a legacy downlink zone and a plurality of first type subframes thereafter, and a start position of the first first type subframe in the legacy support frame structure is the second frame structure. May be the same as the start position of the corresponding subframe or precede one symbol.

Preferably, the size of the legacy downlink zone is defined as 5 + (M-1) * 6, the number of the first type subframe is defined as 5-M, M may be 1 to 3. Preferably, the second frame structure can be used for multi-carrier operation between adjacent carriers. Multi-carrier operation includes permutation across multiple carriers within the same subframe.

According to embodiments of the present invention, communication can be efficiently performed in a wireless communication system supporting multi-carriers. In addition, subframe alignment between frames may be performed when a legacy UE is supported by an adjacent carrier. In addition, the UE may perform the efficient MC operation by matching the boundary of the subframe for the multi-carrier (MC) operation between adjacent FAs or the subframe except for the preamble.

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the following description. .

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included as part of the detailed description in order to provide a thorough understanding of the present invention, provide an embodiment of the present invention and together with the description, illustrate the technical idea of the present invention.

1 illustrates a wireless communication system.

2 illustrates the structure of an OFDMA symbol.

3 illustrates a transmission chain for Advanced Air Interface (AAIF) (ie, IEEE 802.16m system).

4 through 7 illustrate an AAIF radio frame structure.

8 and 9 illustrate an AAIF radio frame structure for legacy support.

10 illustrates an AAIF radio frame structure for multiple carriers.

11 illustrates a communication method using multiple carriers.

12 illustrates subcarrier alignment between adjacent carriers.

FIG. 13 illustrates a case in which subframe boundaries are not aligned between carriers in the prior art.

14 through 16 illustrate a method of aligning subframe boundaries between carriers according to an embodiment of the present invention.

17 and 18 show examples of performing communication according to an embodiment of the present invention.

19 illustrates a block diagram of a base station and a terminal according to an embodiment of the present invention.

The construction, operation, and other features of the present invention will be readily understood by the embodiments of the present invention described with reference to the accompanying drawings. The embodiments described below are examples in which technical features of the present invention are applied to an Institute of Electrical and Electronics Engineers (IEEE) 802.16 system. The present invention can be applied without limitation to an OFDMA system (eg, 3rd Generation Partnership Project (3GPP) system) using a multi-carrier (MC). In a multi-carrier, each carrier is also referred to as a component carrier.

In this specification, the IEEE 802.16m system is mixed with AAIF, and the IEEE 802.16e system is mixed with wireless MAN-OFDMA (Wireless Metropolitan Area Network OFDMA). The IEEE 802.16m system should be backward compatible with the IEEE 802.16e system as the next version of the IEEE 802.16e system. For convenience, the IEEE 802.16m system is referred to as an evolved system, and the IEEE 802.16e system is referred to as a legacy system. It is also referred to as legacy support in which advanced systems reverse support the functionality of legacy systems.

2 shows a structure of an orthogonal frequency division multiple access (OFDMA) symbol. AAIF uses OFDMA as a multiple access technique in uplink / downlink. The OFDMA symbol is mixed with an orthogonal frequency division multiplexing (OFDM) symbol and a single carrier frequency division multiplexing (SC-FDMA) symbol. The OFDMA symbol duration (Ts) in the time domain includes a useful symbol duration (Tb) and a cyclic prefix (CP) (Tg). The effective symbol interval is generated by Inverse-Fourier-transforming. The cyclic prefix is a copy of the last part of the valid symbol interval. In the frequency domain, an OFDMA symbol includes a plurality of subcarriers, and the number of subcarriers is determined by the used FFT (Fast Fourier Transform) size. The subcarrier may be divided into a data subcarrier for data transmission, a pilot subcarrier for estimation purposes, and a null carrier for which no signal is transmitted for a guard band or a DC carrier.

Table 1 shows an example of OFDMA parameters.

Table 1

BW: noial channel band

-N _used : Number of subcarriers _used (including DC subcarriers)

n: sampling factor. The sampling factor, together with BW and N _used , determines the subcarrier spacing and the valid symbol interval. N = 8/7 when the channel band is a multiple of 1.75 MHz and n = 28/25 when the channel band is a multiple of 1.25 MHz.

G: ratio of CP to valid symbol interval. 1/8 and 1/16 can be used.

N _FFT : The smallest number of powers of 2 greater than N _used .

Sampling frequency: F _S = floor (nBW / 8000) * 8000

Subcarrier spacing: Δf = F _S / N _FFT

- CP interval: T _g = G · T _b

OFDMA symbol interval: T _s = T _b + T _g

Sampling time: T _b / N _FFT

Equation 1 shows a voltage of a transmission signal applied to an antenna in an OFDMA symbol as a function of time.

Equation 1

Here, t represents the time elapsed from the start of the OFDMA symbol. C _k represents a complex number. k represents a frequency offset index of a subcarrier to which data is to be transmitted in a corresponding OFDMA symbol. T _g represents the guard time. T _s represents an OFDMA symbol period including a guard time. Δf represents subcarrier spacing.

3 illustrates a transmission chain for AAIF.

Referring to FIG. 3, a medium access control (MAC) block 302 configures MAC data from higher layer data. MAC data may also be referred to as a transport block and correspond to a codeword in a later process. A Forward Error Correction (FEC) block 304 performs channel coding on the MAC data. Channel coding may be performed using Turbo Coding (TC), Convolutional Turbo Coding (CTC), Low Density Parity Check (LDPC), or the like. The coded data may be referred to as codewords or coded packet data. Mod (Modulation) block 306 modulates the coded data. Data modulation may be performed using modulation techniques such as Phase Shift Keying (n-PSK) and Quadrature Amplitude Modulation (n-QAM) (n: integer). Logical Resource Unit (LRU) allocation block 308 divides the modulation symbols into segments of LRU size, and then assigns each segment to an LRU. Mapping block 310 maps the LRU to a data burst. Data bursts are allocated to physical resource units (PRUs) in the physical frequency domain. Accordingly, the mapping block 310 performs a function of mapping the modulated data to the subcarriers according to the mapping relationship between the LRU and the PRU. The IFFT / CP insertion block 310 converts a frequency domain signal into an inverse Fourier transform to a time domain signal, and adds a cyclic prefix to the time domain signal to generate an OFDMA symbol.

4 illustrates a radio frame structure for AAIF. The radio frame structure may be applied to a frequency division duplex (FDD), a half frequency division duplex (H-FDD), a time division duplex (TDD), and the like.

Referring to FIG. 4, the radio frame structure includes a 20 ms superframe SU0-SU3 supporting a 5 MHz, 8.75 MHz, 10 MHz or 20 MHz bandwidth. The superframe includes four 5ms frames (F0-F3) having the same size and starts with a Superframe Header (SFH). The superframe header carries essential system parameters and system configuration information. The superframe header may be located within the first subframe. The superframe header may be classified into primary-SFH (P-SFH) and secondary-SFH (S-SFH). P-SFH is transmitted every superframe. S-SFH may be transmitted every superframe. The superframe header may include a broadcast channel.

The frame includes a plurality of subframes (eg, SF0-SF7). Subframes are allocated for downlink or uplink transmission. The subframe includes a plurality of OFDMA symbols in the time domain and includes a plurality of subcarriers in the frequency domain. The OFDMA symbol may be called an OFDM symbol, an SC-FDMA symbol, or the like according to a multiple access scheme. The number of OFDMA symbols included in the subframe may be variously changed according to the channel bandwidth and the length of the CP. A type of a subframe may be defined according to the number of OFDMA symbols included in the subframe. For example, the type-1 subframe may be defined to include 6 OFDMA symbols, the type-2 subframe includes 7 OFDMA symbols, the type-3 subframe includes 5 OFDMA symbols, and the type-4 subframe includes 9 OFDMA symbols. have.

5 illustrates a frame structure with a type-1 FDD subframe when the size of the cyclic prefix is 1 / 8T _b (G = 1/8). 5 may be used for the 5, 10 and 20 MHz channel bands.

Referring to FIG. 5, a base station supporting an FDD mode may support half duplex and full duplex terminals operating on the same radio frequency (RF) carrier. The UE supporting the FDD mode may use H-FDD or FDD. The FDD frame may be configured based on the frame structure of FIG. 4. In the FDD frame, all subframes are used for DL or UL transmission, and DL / UL transmission is separated in the frequency domain. The FDD terminal may receive a data burst in the DL subframe while accessing the UL subframe. In the case of an H-FDD terminal, only one of transmission or reception is allowed in each subframe. The idle time is located at the end of each FDD frame.

6 shows a frame structure with type-1 TDD subframes.

Referring to FIG. 6, the TDD frame may be configured based on the frame structure of FIG. 4. Contiguous D subframes and the remaining U subframes are allocated to DL and UL, respectively, in a TDD frame with a DL: UL ratio of D: U, and D + U = for 5, 10, and 20 MHz channel bands. 8. For the 5, 10 and 20 MHz channel bands, D: U can be selected from 8: 0, 6: 2, 5: 3, 4: 4 or 3: 5. In each frame, the TTG is inserted between the DL and the UL, and the RTG is inserted at the end of the frame. 6 illustrates a TDD frame with D: U = 5: 3. The TDD frame of FIG. 6 may be applied when G = 1/8 and the channel band is 5, 10 or 20 MHz.

7 illustrates a TDD and FDD frame structure when CP = 1 / 16T _b .

Referring to FIG. 7, a frame structure having a CP length of 1 / 16T _b may include type-1 and type-2 subframes. When the channel bands are 5, 10 and 20 MHz, the frame may include five type-1 subframes and three type-2 subframes. In the case of a TDD frame, the first and last subframes may be type-2 subframes. In the type-2 subframe before the DL => UL switching point, the last OFDMA symbol is used as the idle symbol and covers the gap needed for DL => UL switching. In the case of an FDD frame, the first, fifth and last subframes may be type-2 subframes.

8 and 9 illustrate a frame structure for supporting WirelessMAN-OFDMA.

8 and 9, the WirelessMAN-OFDMA zone and the AAIF zone are divided into frame_offsets (Frame_offset = 1, 2, ..., K). The frame_offset may be indicated in a certain time unit (eg, subframe). Since the AAIF zone must include at least one DL subframe, the maximum value of the parameter K is equal to (number of DL subframes-1). When the AAIF base station coexists with the Wireless-MAN-OFDMA base station, two switching points may be selected in the TDD radio frame.

The subset of DL subframes in the downlink is dedicated for WirelessMAN-OFDMA operation and constitutes one or more WirelessMAN-OFDMA DL time zones. The subset includes a first WirelessMAN-OFDMA DL time zone supporting the transmission of the preamble, the Frame Control Header (FCH) and the MAP. The data burst for the WirelessMAN-OFDMA terminal should not be transmitted in the DL subframe for AAIF operation. Such a DL subframe may be indicated as a DL time zone by transmitting STC_DL_ZONE_IE () (Space Time Coding Downlink Zone Information Element ()) having a dedicated pilot field set to 1 through a DL-MAP message.

Two configurations can be applied in the UL.

1) FDM mode: A subcarrier group (subchannel) spanned over the entire UL transmission interval is dedicated to WirelessMAN-OFDMA operation. The remaining subcarriers, referred to as AAIF subchannel groups, form AAIF subframes and are dedicated to AAIF operation. 8 shows an example of a frame configuration for supporting WirelessMAN-OFDMA operation when the FDM mode is used. The data burst of the WirelessMAN-OFDMA terminal shall not be transmitted on the UL subchannel group for AAIF operation. The UL subchannel group for WirelessMAN-OFDMA operation is determined by UL assigned subchannel bitmap TLV (Type Length Value) or UL Adaptive Modulation & Coding (AMC) assigned physical band bitmap TLV through an Uplink Channel Descriptor (UCD) message. Can be indicated.

2) TDM Mode (FIG. 9): A subset of the UL subframes is dedicated for WirelessMAN-OFDMA operation and may constitute one or more WirelessMAN-OFDMA UL time zones. The subset includes a first Wireless-MAN-OFDMA UL time zone supporting the transmission of a ranging channel, a Channel Quality Indicator (CQI) channel and an Acknowledgment (ACK) channel. 9 shows an example of a frame configuration for supporting WirelessMAN-OFDMA operation when the TDM mode is used. The data burst of the WirelessMAN-OFDMA terminal shall not be transmitted on the UL subframe for AAIF operation. This UL subframe may be indicated to the UL time zone by transmitting UL_ZONE_IE () through a UL-MAP message.

10 illustrates a frame structure for supporting broadband.

Referring to FIG. 10, the frame structure illustrated in FIGS. 4 to 9 may be used for each carrier in a multicarrier operation. Each carrier may have its own superframe header and some carriers may have only a portion of the superframe header. For FDD UL, the preamble and superframe header may be replaced with traffic OFDMA symbols. The plurality of carriers related to the multi-carrier operation may or may not be adjacent in the frequency domain. If the spacing between two adjacent center frequencies is a multiple of subcarrier spacing, guard subcarriers are not needed between adjacent carriers. Each terminal is controlled through an RF carrier identified / configured as a primary carrier. If multiple carriers are supported, the system can improve user experience and quality of service (QoS) or define and use additional RF carriers for specific services. This additional RF carrier is a secondary carrier.

11 illustrates a frame structure supporting multi-carrier operation in the WirelessMAN-OFDMA support mode. Referring to FIG. 11, each carrier in a multicarrier mode supporting WirelessMAN-OFDMA has a basic frame structure (eg, FIG. 4), or a frame structure supporting WirelessMAN-OFDMA (eg, FIG. 8 or 9). Have In a carrier supporting WirelessMAN-OFDMA, uplink may be configured as a TDM. Multi-carrier operation can be applied only between subframes in which AAIF frames are defined. Multicarrier operation is not defined between the AAIF frame and the WirelessMAN-OFDMA frame.

12 shows an example of aligning subcarriers in a multicarrier operation.

Referring to FIG. 12, when adjacent carriers are used in a multicarrier operation, overlapped guard subcarriers may be aligned in a frequency domain. In order to align overlapping subcarriers of the OFDMA signal transmitted on an adjacent carrier, a permanent frequency offset Δf 'may be applied to the original center frequency. Specifically, during the network entry process, the base station can inform the terminal of the frequency offset applied to each carrier.

On the other hand, when adjacent carriers are involved in multi-carrier operation, guard subcarriers between adjacent frequency channels may be used for data transmission. For example, during a network entry process, the base station can inform the terminal of information on available guard subcarriers that can be used for data transmission. In addition, when adjacent carriers are involved in a multi-carrier operation, permutation may be performed over a plurality of carriers within the same subframe.

Permutation refers to a method in which a base station maps a resource unit to transmit and receive a signal with a terminal. In the IEEE 802.16m system, permutation includes outer permutation and inner permutation. External permutation divides the entire band into subband regions and miniband regions, and distributes frequency resources of the miniband region in units of PRUs. Thereafter, the subband region and the miniband region are allocated to frequency partitions. Each frequency partition includes a distributed resource allocation area and / or a continuous resource allocation area. Permutation is additionally performed in the distributed resource allocation area, and internal permutation is not applied to the continuous resource allocation area. Internal permutation distributes frequency resources in units of frequency pairs within a distributed resource region.

FIG. 13 exemplifies a case in which subframe boundaries do not coincide between adjacent frequency allocations (FAs). FA corresponds to each carrier in the multi-carrier. FIG. 13 assumes a situation where two neighboring carriers exist to help understand the conventional problem. FIG. 13 assumes that a legacy support frame structure and an AAIF only frame structure are used for adjacent FAs in a 5/10 / 20MHz band. In this example, the legacy support frame structure assumes TDM, but there is no limitation of the present invention even in the case of FDM.

Referring to FIG. 13, the number of legacy OFDMA symbols in the legacy support frame structure of FA1 is defined as 5 + 6 * (Frame_offset-1). Therefore, when Frame_offset is 2, the number of legacy OFDMA symbols is 11. On the other hand, it is assumed that FA1 and FA2 are adjacent to each other, and that FA2 has a frame structure that operates only AAIF. According to the current 802.16m standard document, the DL frame for AAIF is basically configured as a type-1 subframe and the last subframe is configured as a type-3 subframe. In this case, temporal alignment between subframes is required to perform the MC operation on a subframe basis for the last three subframes of the DL. For example, temporal alignment between subframes is required to mix resources of frequency stages by using one physical permutation in subframe units in adjacent FAs.

14 to 16 illustrate an example of aligning (subframe alignment) a boundary of a subframe between adjacent FAs according to an embodiment of the present invention. For simplicity, only the multi-carrier support situation on two adjacent carriers FA1 and FA2 is assumed. However, as an example, the present invention may be applied to three or more carriers in a multi-carrier situation, and may be applied even when the carriers are not adjacent.

In the present invention, the subframe alignment means that the boundaries (or subframe regions) of subframes (eg, subframes having the same index) corresponding to each other are configured in different carriers and have a predetermined relationship. For example, in the present invention, subframe alignment includes a case where a boundary (or subframe region) of a corresponding subframe is completely matched (aligned). In this case, the corresponding subframes have the same number of symbols, the start position of the symbol in the frame, and the like. In addition, in the present invention, subframe alignment includes a case where a boundary (or subframe region) of a corresponding subframe does not completely match but a specific region (eg, a permutation performing region) matches (aligns). That is, symbols (eg, symbols for preamble and midamble) that are not reflected in the permutation may not be considered when subframe alignment. In this case, the corresponding subframes may differ in the number of symbols, the start position of the symbol in the frame, and the like. This will be described in detail with reference to FIG. 14.

Although the legacy support frame structure assumes TDM in this embodiment, there is no limitation of the present invention even in the case of FDM. It is assumed that legacy support frame structure is used for FA1 and AAIF only frame structure is used for FA2. 14, 15, and 16 show an example where Frame_offset is 1, 2, and 3, respectively. Currently, the maximum value of Frame_offset in the 802.16m standard document is limited to 3, so this example can cover all possible cases.

Referring to FIG. 14, when Frame_offset is 1, the number of legacy OFDM symbols in the legacy support frame structure of FA1 is five. That is, in the legacy support frame structure, the first five OFDM symbols are used as legacy DL zones (WirelessMAN-OFDMA DL Zone), and the remaining six symbols constitute AAIF type-1 subframes. In this case, one type-3 subframe may be located in the second subframe in the AAIF frame structure of FA2 for subframe alignment between FAs. For precise alignment with legacy support frames, one can also consider placing the type-3 subframe in the first subframe of the AAIF frame, but the first subframe is type-1 because of the common structure of the Super Frame Header (SFH). It should be configured as The same applies to the first subframe of the AAIF DL zone in the legacy support frame structure.

If the type-3 subframe is located in the second subframe of the AAIF frame, the first AAIF subframe (FA1AAIF, 1; 1410) of the legacy support frame and the second subframe of the AAIF-only frame (FA2AAIF, 2; 1420). ) Does not align the boundaries correctly. Due to the type difference of the two subframes, FA2AAIF, 2 is aligned with the second through sixth symbols of FA1AAIF, 1. However, since the first symbol of the first subframe of the AAIF DL zone is typically used as a preamble, the parts except for this are coincident with each other. In general, since the MC operation does not occur in the preamble region, performing the MC operation (eg, permutation, other operations) in the data / control region except for the preamble region is still valid even when the frame_offset is 1.

15 and 16, when Frame_offset is 2 and 3, the number of legacy OFDM symbols in the legacy support frame structure of FA1 is 11 and 17, respectively. Therefore, when one type-3 subframe is located in the second subframe in the AAIF frame structure of FA2, the boundaries of all subframes located in the AAIF DL zone are aligned. If Frame_offset is 2, one type-3 subframe in the AAIF frame structure of FA2 may also be located in the third subframe. In this case, the type-3 subframe of FA2 is not aligned with the start symbol of the first AAIF subframe of FA1. However, as described with reference to FIG. 14, since the data / control region is aligned with the type-3 subframe of FA2 and the first AAIF subframe of FA1, the MC operation may be performed between adjacent carriers. Similarly, when Frame_offset is 3, one type-3 subframe in the AAIF frame structure of FA2 may be located in the third or fourth subframe. If the type-3 subframe of FA2 is located in the fourth subframe, the type-3 subframe of FA2 and the first AAIF subframe of FA1 are not aligned with the start symbol, but the data / control area where the MC operation is performed. Are sorted.

As described above, the position of one type-3 subframe in the AAIF frame structure may be variously set according to Frame_offset. In this case, the location of the type-3 subframe may be allocated to different locations according to Frame_offset. As an example, the location of the type-3 subframe may be defined as the (Frame_offset + 1) th subframe. Meanwhile, in order to simplify system operation, the location of the type-3 subframe may be fixed to a specific (eg, second) subframe.

17 shows an example of downlink transmission according to an embodiment of the present invention.

Referring to FIG. 17, the base station generates a plurality of symbols included in a subframe (S1710). The symbol includes an OFDMA symbol and may be generated by the transmission chain illustrated in FIG. 3. Thereafter, the base station selectively transmits the plurality of subframes to the terminal by using the first frame structure or the second frame structure (S1720). Which frame structure to use in the physical layer may be indicated from a higher layer or may be automatically selected in the physical layer according to a predetermined rule. For example, a frame structure to be used may be signaled in consideration of at least one of whether a multi-carrier is supported, whether a multi-carrier is operated, whether a legacy support frame structure is used, and a frame_offset. Also, using this information, the frame structure to be used may be indicated implicitly / indirectly. The base station may explicitly signal information indicating a frame structure to be used to the terminal, or implicitly signal the terminal using the above-described information.

The first frame structure includes a frame structure for AAIF. That is, the first frame structure may include the frame structure illustrated in FIGS. 4 to 8. Preferably, the first frame structure includes a plurality of contiguous first type subframes and then one or more second type subframes. In this case, the first type subframe includes a type-1 subframe for AAIF, and the second type subframe includes a type-3 subframe for AAIF. The second frame structure represents a frame structure introduced to match subframe boundaries between adjacent carriers. The second frame structure includes the same number of second type subframes as the first number of subframe types. However, at least one second type subframe is located between the plurality of first type subframes in order to change the subframe boundary. As an example, the second type frame structure includes the frame structure illustrated in FIGS. 14 to 16. The first type frame structure and the second type frame structure may be used for FDD, H-FDD or TDD.

18 shows an example of processing a downlink signal according to an embodiment of the present invention.

Referring to FIG. 18, the terminal receives a plurality of symbols from the base station (S1810). The symbol includes an OFDMA symbol. Thereafter, the terminal selectively uses the first frame structure or the second frame structure to process the plurality of symbols in subframe units (S1820). Physical signal processing is performed in the reverse direction in the transmission chain illustrated in FIG. Which frame structure the terminal uses is explicitly signaled from the base station, or can be confirmed implicitly / indirectly using other information. For example, which frame structure to use may be determined using at least one of whether a multicarrier is supported, whether a multicarrier operation is performed, a legacy support frame structure, and frame_offset information. Since the first frame structure and the second frame structure are the same as those illustrated in FIG. 17, details of FIG. 17 are referred to.

19 illustrates a base station and a terminal that can be applied to an embodiment in the present invention.

Referring to FIG. 19, a wireless communication system includes a base station (BS) 110 and a terminal (UE) 120. In downlink, the transmitter is part of the base station 110 and the receiver is part of the terminal 120. In uplink, the transmitter is part of the terminal 120 and the receiver is part of the base station 110. Base station 110 includes a processor 112, a memory 114, and a radio frequency (RF) unit 116. The processor 112 may be configured to implement the procedures and / or methods proposed in the present invention. The memory 114 is connected to the processor 112 and stores various information related to the operation of the processor 112. The RF unit 116 is connected with the processor 112 and transmits and / or receives a radio signal. The terminal 120 includes a processor 122, a memory 124, and an RF unit 126. The processor 122 may be configured to implement the procedures and / or methods proposed by the present invention. The memory 124 is connected with the processor 122 and stores various information related to the operation of the processor 122. The RF unit 126 is connected with the processor 122 and transmits and / or receives a radio signal. The base station 110 and / or the terminal 120 may have a single antenna or multiple antennas.

The embodiments described above are the components and features of the present invention are combined in a predetermined form. Each component or feature is to be considered optional unless stated otherwise. Each component or feature may be embodied in a form that is not combined with other components or features. It is also possible to combine some of the components and / or features to form an embodiment of the 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. It is obvious that the claims may be combined to form an embodiment by combining claims that do not have an explicit citation relationship in the claims or as new claims by post-application correction.

In this document, embodiments of the present invention have been mainly described based on data transmission / reception relations between a terminal and a base station. Certain operations described in this document as being performed by a base station may in some cases be performed by an upper node thereof. That is, it is apparent that various operations performed for communication with the terminal in a network including 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. A base station may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an access point, and the like. In addition, the terminal may be replaced with terms such as a user equipment (UE), a mobile station (MS), a mobile subscriber station (MSS), and the like.

Embodiments according to the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of a hardware implementation, an embodiment 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), FPGAs ( field programmable gate arrays), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, procedure, function, etc. 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.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit 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.

The present invention can be applied to a wireless communication system. Specifically, the present invention can be applied to a method and apparatus for performing communication in a multi-carrier situation.

Claims

In a method for transmitting a downlink signal by a base station in an orthogonal frequency division multiple access (OFDMA) system supporting a multi carrier (Multi Carrier),

Generating a plurality of symbols included in the subframe; And

Selectively transmitting a plurality of subframes to the terminal using a first frame structure or a second frame structure,

The first frame structure includes a plurality of consecutive first type subframes and one or more second type subframes thereafter,

The second frame structure includes the plurality of first type subframes and the one or more second type subframes, wherein at least one second type subframe is located between the plurality of first type subframes. Signal transmission method.
The method of claim 1,

The first frame structure and the second frame structure each downlink signal transmission method characterized in that it comprises a first downlink structure and a second downlink structure shown in the following table:

Here, SF represents a subframe index, each number represents the number of symbols included in the subframe, any one of X 1 to X 3 is 5 and the other two represents 6.
The method of claim 2,

X 1 is 5, X 2 and X 3 is 6 characterized in that the downlink signal transmission method.
The method of claim 1,

A second frame structure is used for the first carrier,

A legacy support frame structure is used for a second carrier adjacent to the first carrier.
The method of claim 4, wherein

The legacy support frame structure includes a legacy downlink zone and a plurality of first type subframes thereafter,

And a start position of a first first type subframe in the legacy support frame structure is equal to or equal to a start position of a corresponding subframe in the second frame structure.
The method of claim 5,

The size of the legacy downlink zone is defined as 5 + (M-1) * 6, the number of the first type subframe is defined as 5-M, the M downlink signal characterized in that 1 to 3 Transmission method.
The method of claim 1,

And the second frame structure is used for multi-carrier operation between adjacent carriers.
A base station of an orthogonal frequency division multiple access (OFDMA) system supporting a multi carrier (Multi Carrier),

A radio frequency (RF) unit configured to transmit and receive a radio signal with a terminal;

A memory for storing information transmitted and received with the terminal and parameters necessary for the operation of the base station; And

A processor coupled to the RF unit and the memory, the processor configured to control the RF unit and the memory, wherein the processor includes:

Generating a plurality of symbols included in the subframe; And

Selectively transmitting a plurality of subframes to the terminal using a first frame structure or a second frame structure,

The first frame structure includes a plurality of consecutive first type subframes and one or more second type subframes thereafter,

The second frame structure includes the plurality of first type subframes and the one or more second type subframes, wherein at least one second type subframe is located between the plurality of first type subframes. A base station configured to perform a signal transmission method.
In a method of processing a downlink signal by a terminal in an orthogonal frequency division multiple access (OFDMA) system supporting a multi-carrier (Multi Carrier),

Receiving a plurality of symbols from a base station;

Selectively processing the plurality of symbols in subframe units using a first frame structure or a second frame structure,

The first frame structure includes a plurality of consecutive first type subframes and one or more second type subframes thereafter,

The second frame structure includes the plurality of first type subframes and the one or more second type subframes, wherein at least one second type subframe is located between the plurality of first type subframes. Signal processing method.
The method of claim 9,

The first frame structure and the second frame structure each of the downlink signal processing method characterized in that it comprises a first downlink structure and a second downlink structure described in the following table:

Here, SF represents a subframe index, each number represents the number of symbols included in the subframe, any one of X 1 to X 3 is 5 and the other two represents 6.
The method of claim 10,

X 1 is 5, X 2 and X 3 is 6 characterized in that the downlink signal processing method.
The method of claim 9,

The second frame structure is used for a first carrier,

The legacy support frame structure is used for a second carrier adjacent to the first carrier.
The method of claim 12,

The legacy support frame structure includes a legacy downlink zone and a plurality of first type subframes thereafter,

And a start position of a first first type subframe in the legacy support frame structure is equal to or one symbol ahead of a start position of a corresponding subframe in the second frame structure.
The method of claim 13,

The size of the legacy downlink zone is defined as 5 + (M-1) * 6, the number of the first type subframe is defined as 5-M, the M downlink signal characterized in that 1 to 3 Treatment method.
The method of claim 9,

And the second frame structure is used for multi-carrier operation between adjacent carriers.