KR20170007175A - Low latency transmission method and apparatus - Google Patents

Abstract

A base station supports a low latency mode of a terminal through a legacy downlink sub frame which is transmitted with a first transmission time interval (TTI) in a downlink main component carrier and transmits control information and low latency downlink data to the terminal which is operated in a low latency mode, through a downlink sub slot which is transmitted with a second TTI unit in a downlink sub component carrier. Accordingly, the present invention can support a low latency service while maintaining compatibility with technology of an existing LTE system.

Description

[0001] LOW LATENCY TRANSMISSION METHOD AND APPARATUS [0002]

The present invention relates to a low-delay transmission method and apparatus, and more particularly, to a low-delay transmission method and apparatus capable of supporting a legacy LTE (Long Term Evolution) system and supporting a low-delay service based on a legacy LTE system.

Advances in communications technology are designed to support the compatibility of previous technologies and to support the following technologies. As the fourth generation LTE system evolves into the fifth generation, it should support the 4th generation LTE system and the 5th generation technology should be applied on the 4th generation LTE system.

In the fifth generation technology, low delay technology is required with a higher data rate. A low-latency technique is a technique that reduces the time it takes for a base station or terminal to transmit data and receive a response. Low-latency technologies require new rates and response rates while maintaining compatibility with existing fourth-generation technologies. The present invention proposes a base station, a terminal-to-terminal control scheme, and a low-delay frame structure supporting the existing LTE based on the LTE based on the fourth generation communication method and supporting the low-delay service.

A problem to be solved by the present invention is to provide a low-delay transmission method and apparatus capable of supporting a low-delay service while maintaining compatibility with a technology of an existing LTE system.

According to one embodiment of the present invention, a low delay transmission method at a base station is provided. The low delay transmission method includes supporting a low delay mode of a UE through a legacy downlink subframe transmitted in a first transmission time interval (TTI) unit on a downlink primary carrier, And transmitting the control information and the low-delay downlink data to the UE operating in the low-delay mode through a downlink sub slot transmitted to the UE.

The second TTI unit may be shorter than the first TTI unit.

Wherein a sampling rate on the downlink sub-element carrier is set to an integral multiple of a sampling rate on the downlink sub-carrier, the carrier interval and the system bandwidth on the downlink sub-carrier are respectively equal to the sub- It can be set to an integer multiple of the system bandwidth.

Wherein the time length of the legacy downlink subframe includes a plurality of downlink sub slots and each of the plurality of downlink sub slots includes a plurality of short symbols, And assigning a cell specific reference signal to the symbol.

The transmitting may further include assigning a UE-specific reference signal to the remaining symbols except for the first symbol among the plurality of short symbols.

The low-delay transmission method may further include transmitting a synchronization signal and system information through the downlink main carrier.

Wherein the step of supporting comprises transmitting low-delay information through a control channel of the legacy downlink sub-frame, wherein the low-delay information includes a carrier frequency of a sub-carrier, a number of symbols in the second TTI unit, , A sampling rate, and a system bandwidth.

The low delay transmission method may further include transmitting a low delay connection release requesting the terminal to turn off the low delay mode through the legacy downlink subframe or the downlink sub slot.

The low-delay transmission method includes a low-delay connection for notifying the terminal of a low-delay mode through a legacy uplink subframe transmitted in the first TTI unit or an uplink sub slot transmitted in the second TTI unit from the terminal The method may further include receiving a release.

The low-delay transmission method may further include receiving control information and low-delay uplink data from the UE through an uplink sub slot transmitted on the uplink sub-carrier on the second TTI basis.

Wherein the time length of the legacy uplink subframe transmitted in the first TTI unit includes a plurality of uplink sub slots and each of the plurality of uplink sub slots includes a plurality of short symbols, And receiving a SRS (Sounding Reference Signal) through the last short symbol of the last uplink sub slot of the plurality of uplink sub slots.

According to another embodiment of the present invention, a low delay transmission method in a terminal is provided. The low-delay transmission method includes: receiving low-delay information for a low-delay mode of the UE through a legacy downlink sub-frame transmitted in a first transmission time interval (TTI) on a downlink main carrier from the base station; And acquiring the control information and the low-delay downlink data through the sub-slot of the downlink transmitted in the second TTI unit on the downlink sub-carrier using the delay information.

The low-delay transmission method may further include transmitting control information and low-delay uplink data to the base station through an uplink sub slot transmitted in the second TTI unit on the uplink sub-carrier.

Wherein the step of transmitting the control information and the low-delayed uplink data to the base station comprises the step of transmitting the control information and the low-delayed uplink data to the base station in the last uplink sub-slot of the plurality of uplink sub-slots included in the time length of the legacy uplink sub- And transmitting a Sounding Reference Signal (SRS) through a short symbol.

The time length corresponding to the legacy downlink subframe may include a plurality of downlink sub slots.

Wherein a sampling rate in the downlink sub-element carrier is set to an integral multiple of a sampling rate in the downlink sub-carrier, the sub-carrier spacing and the system bandwidth in the downlink sub-carrier are respectively a sub- It can be set to an integer multiple of the system bandwidth.

The low-delay information may include at least one of a carrier frequency of a sub-carrier, a number of symbols in the second TTI unit, a sub-carrier interval, a sampling rate, and a system bandwidth.

Wherein the acquiring comprises: receiving location and size information of a common DCI (Downlink control information) region of a control channel in the downlink sub slot from the base station and a UE-specific DCI location and size information; And receiving the common DCI and the UE-specific DCI based on the size information and the UE-specific DCI location and size information.

According to another embodiment of the present invention, a low-delay transmission apparatus is provided. The low delay transmission device includes a processor and a transceiver. Wherein the processor performs scheduling for data transmission in a first transmission time interval (TTI) on a primary carrier, performs scheduling for data transmission in a secondary TTI unit on a secondary carrier, And carries out resource allocation for uplink and downlink physical channels for a carrier wave. Then, the transceiver transmits data and uplink and downlink resource allocation information through the main carrier wave or sub-element carrier wave. The second TTI unit may be shorter than the first TTI unit.

The time length of one subframe includes a plurality of sub-slots, the first TTI unit is set to a time length of the one subframe, the second TTI is set to a time length of one sub-slot, The processor may assign a cell-specific reference signal (CRS) in a downlink to a first short symbol among a plurality of short symbols in each sub-slot.

According to the embodiment of the present invention, by using a 1-ms legacy TTI on a main carrier to support a legacy service and using a short TTI on a subcarrier using a frequency resource different from that of a main carrier to support a low- , The processing clock of the modem processing one element carrier can be separated into the legacy service and the low delay service and the processing speed of the modem for processing the element carrier according to the increase of the sampling rate for the low delay service can be increased. In addition, since L1 control is different for each element carrier due to the difference between the short TTI and the length of the legacy TTI, L1 control is simpler than the method of transmitting the legacy TTI and the short TTI at the same time, and resources and low- The transmission rate of the legacy TTI and the short TTI can be increased.

In addition, in a short TTI structure, a ratio of resources occupied by an existing signal can be minimized. In particular, when a CRS is allocated only to a first symbol within a short TTI, a UE-specific reference signal can be allocated to the remaining symbols, .

Also, since the initial connection and the low delay mode are set using the main carrier wave and the uplink and downlink communication can be performed using only the low delay mode, the uplink and downlink transmission delays can be reduced.

1 is a diagram showing an example of a frame structure of a legacy LTE system.
2 and 3 are diagrams illustrating an example of a multi-component carrier supported by a legacy LTE system, respectively.
4 is a diagram illustrating an example of a downlink sub-frame of the low-delay system according to Table 1.
5 is a diagram illustrating an example of a downlink sub-frame of the low-delay system according to Table 2 and Table 3. FIG.
FIG. 6 is a diagram illustrating an example of a UL subframe of the low-delay system according to Table 1. FIG.
FIG. 7 is a diagram illustrating an example of an uplink sub-frame of the low-delay system according to Tables 2 and 3. FIG.
8 to 10 are diagrams illustrating a low-delay transmission method according to an embodiment of the present invention.
11 to 14 are diagrams illustrating a method of terminating a low-delay service according to an embodiment of the present invention.
15 is a diagram illustrating a low-delay transmission apparatus of a base station according to an embodiment of the present invention.
16 is a diagram illustrating a low-delay transmission apparatus of a terminal according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification and claims, when a section is referred to as "including " an element, it is understood that it does not exclude other elements, but may include other elements, unless specifically stated otherwise.

Throughout the specification, a terminal is referred to as a mobile terminal (MT), a mobile station (MS), an advanced mobile station (AMS), a high reliability mobile station (HR- A subscriber station (SS), a portable subscriber station (PSS), an access terminal (AT), a user equipment (UE) , HR-MS, SS, PSS, AT, UE, and the like.

Also, a base station (BS) is an advanced base station (ABS), a high reliability base station (HR-BS), a node B, an evolved node B, eNodeB), an access point (AP), a radio access station (RAS), a base transceiver station (BTS), a mobile multihop relay (MMR) (RS), a relay node (RN) serving as a base station, an advanced relay station (ARS) serving as a base station, a high reliability relay station (HR) A femto BS, a home Node B, a HNB, a pico BS, a metro BS, a micro BS, ), Etc., and all or all of ABS, Node B, eNodeB, AP, RAS, BTS, MMR-BS, RS, RN, ARS, HR- And may include negative functionality.

Now, a low-delay transmission method and apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram illustrating an example of a frame structure of a legacy LTE system, and FIGS. 2 and 3 are views showing an example of a multi-element carrier supported by a legacy LTE system, respectively.

1, in a legacy LTE (Long Term Evolution) system, which is a typical mobile communication system, one frame has 20 slots (# 0 to # 19) having a length of 10 ms in the time domain and a length of 0.5 ms, .

One subframe has a length of 1 ms and is composed of two slots. Each slot includes a plurality of symbols in the time domain and a plurality of subcarriers in the frequency domain. Symbol may be referred to as an Orthogonal Frequency Division Multiplex (OFDM) symbol, an OFDMA symbol, a Single Carrier-Frequency Division Multiple Access (SC-FDMA) symbol, or the like according to a multiple access scheme. The number of symbols included in one slot can be variously changed according to the channel bandwidth or the length of the cyclic prefix (CP). For example, in the case of a normal CP, one slot includes seven symbols, while in the case of an extended CP, one slot includes six symbols.

The legacy LTE system defines the minimum unit of time resource for transmitting data as TTI. The TTI is set equal to the length of one subframe. That is, the TTI has a length of 1 ms. A resource block (RB), which is a basic unit for data transmission in the physical layer, is composed of a plurality of symbols and a plurality of subcarriers. For example, in the case of a general CP, one RB may be composed of 12 subcarriers and 7 symbols.

In a legacy LTE system, the operation bandwidth of one elementary carrier is maximum 20 MHz, and the actual transmission bandwidth is 18 MHz. The remaining frequency bands other than the actual transmission bandwidth can be used as the guard band. Therefore, the subcarrier interval in the used band within the actual transmission bandwidth is set to 15 kHz, the bandwidth of one RB is about 180 kHz, and a maximum of 100 RBs can be included in the used band. At this time, the number of RBs may vary depending on the operating bandwidth. The sampling rate is set to 30.72 MHz, and the time it takes to transmit one sample is 0.326us. The FFT (Fast Fourier Transform) size is set to 2048. The length of one subframe is 30720 * Ts, and Ts is 1 / (15000 * 2048) s.

One symbol consists of a CP and a valid symbol interval, and the CP includes 160 samples or 144 samples. Therefore, the transmission time (or length) of the CP having 144 samples is 4.69 us, and the transmission time of the effective symbol interval including 2048 samples is 66.67 us.

Thus, legacy LTE systems operate at a sampling rate of 30.72 MHz and support scalable bandwidths of 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz. In addition, legacy LTE systems can support multi-element carrier systems using carrier aggregation. A multi-element carrier system can use carrier aggregation to aggregate element carriers having bandwidths supported by an LTE system to support a wider bandwidth. For the backward compatibility with the legacy LTE system, the bandwidth used by the legacy LTE system may be used as the bandwidth of the element carrier wave or an integer multiple of the bandwidth may be used.

As shown in Figs. 2 and 3, the bandwidths of the element carriers used for carrier aggregation may be equal to or different from each other. As shown in FIG. 2, a broadband can be configured using element carriers of a bandwidth (20 MHz) supported by a legacy LTE system. As shown in FIG. 3, a bandwidth (20 MHz) supported by a legacy LTE system and a new bandwidth (M * 20 MHz) component carriers can be used to form a wideband. Where M is an integer. That is, the new bandwidth (M * 20 MHz) can be set to an integer multiple of the bandwidth (20 MHz) supported by the legacy LTE system.

In addition, the element carriers used for carrier aggregation have different frequency bands (or center frequencies). Also, the element carriers used for carrier aggregation may be on a continuous frequency band, but may also be on a discontinuous frequency band.

Element carriers used for carrier aggregation can be classified into one primary component carrier (PCC) and at least one secondary component carrier (SCC0, SCC1). The primary carrier wave PCC may be referred to as a Pcell or the secondary carrier wave SCC0 or SCC1 may be referred to as a secondary cell SCELL.

A terminal may use only one major carrier (PCC) or one or more sub-carrier (SCC0, SCC1) with a primary carrier (PCC). The MS can receive a primary carrier (PCC) and / or a secondary carrier (SCC0, SCC1) from a base station.

The number of element carriers to be aggregated between the downlink and the uplink may be set differently. The element carriers that are aggregated in the downlink are transported as downlink elements, and the element carriers that are aggregated in the uplink are transported as uplink elements. The case where the number of downlink element carriers is equal to the number of uplink element carriers is referred to as symmetric aggregation, and the case where the number of downlink element carriers is different is referred to as asymmetric aggregation. The uplink component carrier and the downlink component carrier may have different frequency bands.

A legacy LTE system uses a short TTI (hereinafter referred to as "sTTI (short TTI)") shorter than a 1 ms legacy TTI to support low delay. A frame having a legacy TTI is referred to as a legacy frame, and a frame having an sTTI is referred to as a low-delay frame.

According to an embodiment of the present invention, a legacy frame is used on a main carrier and a low delay frame is used on a sub carrier. That is, the physical channel in the low delay frame uses a different frequency resource than the physical channel in the legacy frame. Also, since the legacy TTI and the sTTI have different lengths, L1 (layer 1) control is performed for each element carrier.

In the low delay frame, the subcarrier interval is set to an integral multiple (15 kHz x M) of the subcarrier interval of 15 kHz, the total system bandwidth includes Z RBs, and one RB may include B subcarriers.

The subcarrier spacing of 15 kHz x M can constitute a low-delay system with a sampling rate of 15 x M x 2 ^Q. 2 ^Q is the FFT size for calculating the sampling rate.

The low-delay system according to the embodiment of the present invention supports a variable bandwidth within the maximum bandwidth of the low-delay system and supports a sub-carrier using only the low-delay terminal operating in the sTTI. The short TTI has 1 / Kms and the sTTI can be composed of T symbols. A symbol in sTTI is called a short symbol, and a short symbol may have a time length of (CP length + 2 ^Q ) / (15 * M * 2 ^Q ).

Tables 1 to 3 each show an example of the subcarrier interval and the maximum bandwidth in the low-delay system according to the embodiment of the present invention. In Table 1 to Table 3, the parameter values of the low delay system are compared with the LTE system, respectively.

Legacy LTE systems Low delay system (M = 2) Subcarrier spacing 15kHz 15xM = 30kHz 1 Number of subcarriers in RB 1RB = 12 SC
1RB = 15 kHz x 12 = 180 kHz 1RB = 12SC
1RB = 30 kHz x 12 = 360 kHz Sampling rate 15 kHz x 2048 = 30.72 MHz (15 kHz x 2) x 1024 = 30.72 MHz Maximum bandwidth 20MHz 20MHz Total RB, resource bandwidth 18 MHz 18MHz, 600RB CP length 160, 144 samples 256 samples 1 (s) Number of symbols in TTI 14 symbol 6 symbol 1 (s) TTI length 1ms, 30720 samples 250us, 7680 samples

Legacy LTE systems Low delay system (M = 4) Subcarrier spacing 15kHz 15 kHz x 4 = 60 Hz (M = 4) 1 Number of subcarriers in RB 1RB = 12SC
1RB = 15 kHz x 12 = 180 kHz 1RB = 12SC
1RB = 15 kHz x M x 12 (720 kHz) Sampling rate 15 kHz x 2048 = 30.72 MHz (15 kHz x M) x 512 (30.72 MHz) Maximum bandwidth 20MHz 20MHz Total RB, resource bandwidth 18 MHz 18 MHz CP length 160, 144 samples 128 samples 1 (s) Number of symbols in TTI 14 symbol 12 symbol 1 (s) TTI length 1ms, 30720 samples 250us, 7680 samples

Legacy LTE systems Low delay system (M = 4) Subcarrier spacing 15kHz 15 kHz x M (M = 4) 1 Number of subcarriers in RB 1RB = 12 SC
1RB = 15 kHz x 12 = 180 kHz 1RB = 12SC
1RB = 15 kHz x M x 12 (720 kHz) Sampling rate 15 kHz x 2048 = 30.72 MHz (15 kHz x M) x 1024 (61.44 MHz) Maximum bandwidth 20MHz 40 MHz Total RB, resource bandwidth 18 MHz 600SC x 15kHz (36MHz) CP length 160, 144 256 1 (s) Number of symbols in TTI 14 symbol 12 symbol 1 (s) TTI length 1ms. 30720 samples 250us, 15360 samples

Thus, the maximum bandwidth of the sub-carrier supported by the low-delay system can be M times the maximum bandwidth of the LTE system due to the extended sub-carrier interval that is an integral multiple of the sub-carrier interval in the legacy LTE system. It can support variable bandwidth. Where M is an integer greater than zero.

The bandwidth of the sub-element carrier shown in Tables 1 to 3 is the maximum bandwidth of the low-delay system, and it should be able to support the variable bandwidth supported by the legacy LTE system. That is, the number of RBs and the sampling rate can be lowered within the maximum sampling rate and the maximum bandwidth as in the legacy LTE system.

4 is a diagram illustrating an example of a downlink sub-frame of the low-delay system according to Table 1.

Referring to FIG. 4, scheduling for data transmission is performed on a downlink main carrier (PCC) in units of legacy TTI as in the case of a legacy LTE system, and synchronization signals and system information are transmitted through a downlink main carrier (PCC) do.

The downlink subframe of the downlink primary carrier (PCC) may be configured the same as the downlink subframe of the legacy LTE system.

A downlink sub-frame of a downlink primary carrier (PCC) is divided into a control region and a data region in a time domain. The control region includes a maximum of three symbols of the first slot in the subframe, but the number of symbols included in the control region can be changed. A control channel may be assigned a downlink control channel, and a data channel may be allocated a downlink data channel.

In a legacy LTE system, a physical downlink control channel (PDCCH), a physical control format indicator channel (PCFICH), and a physical hybrid-ARQ indicator channel (PHICH) . The PCFICH includes a control format indicator (CFI) regarding the number of symbols transmitted in the first symbol of the subframe and used for transmission of the control channels in the subframe (i.e., the size of the control region). Unlike the PDCCH, the PCFICH does not use blind decoding, but is transmitted through the resources of the fixed PCFICH of the subframe. The PHICH is transmitted in the first symbol of the subframe and includes a positive-acknowledgment (ACK) / negative-acknowledgment (NACK) signal for a hybrid automatic repeat request (HARQ). The ACK / NACK signal for the uplink data transmitted by the UE is transmitted through the PHICH. The PBCH (Physical Broadcast Channel) is transmitted in the first four symbols of the second slot of the first subframe of the radio frame.

The PBCH carries the system information necessary for the terminal to communicate with the base station, and the system information transmitted through the PBCH is called the master information block (MIB). The MIB includes system bandwidth, system frame number (SFN), and PHICH configuration information. The PHICH setting information may include a PHICH period and a PHICH resource indicating the number of symbols to which the PHICH is transmitted. The UE receives the MIB transmitted through the PBCH and obtains information on SFN synchronization, PHICH setup, and system bandwidth between the base station and the UE.

In a legacy LTE system, a synchronization signal is used when performing cell search, and a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) are used as synchronization signals. The PSS is transmitted in the last symbol of the first slot of the first subframe and the first slot of the sixth subframe, and the SSS is transmitted in the symbol immediately preceding the symbol to which the PSS is allocated. After powering on the terminal, the PSS and the SSS transmitted from the base station are detected to detect a CP (Cyclic Prefix) type, a radio frame synchronization, a symbol synchronization, and a cell identifier to which the UE 200 belongs.

The synchronization signal and the PBCH are transmitted in the middle six RBs in the system bandwidth at the downlink main carrier (PCC) so that the terminal can detect or decode regardless of the transmission bandwidth.

In addition, a cell-specific reference signal (CRS) is transmitted over the entire downlink bandwidth in all downlink subframes in the cell, and is transmitted from all antenna ports of the base station. CRS can be allocated to a certain position in each RB in all RBs. The position of the CRS in the time domain can be arranged at regular intervals starting from the first symbol of each slot. The time interval is defined differently depending on the CP length. In the case of a general CP, it is located in the first and fifth symbols (l = 0, l = 4) of each slot. One symbol may define a CRS for up to two antenna ports.

The downlink sub-frame of the downlink sub-element carrier wave (SCC0) may include four sub-slots operating in units of sTTI. Each sub-slot is assigned a low-delay downlink physical channel having the same function as PDCCH, PHICH, PDSCH, and PCFICH. PDCCH, PHICH, PDSCH, and PCFICH used in the downlink sub-carrier (SCC0) are referred to as sPDCCH, sPHICH, sPDSCH, and sPCFICH, respectively. The CRS used in the sub-element carrier is also referred to as sCRS.

As shown in Table 1, one sub-slot in the downlink sub-carrier (SCC0) may include six short symbols and may be divided into a control region and a data region in the time domain. The control area includes one short symbol, but the number of short symbols included in the control area can be changed. sPDCCH and sPHICH are transmitted on the first symbol of the sTTI, and the sPDSCH can be transmitted on the remaining symbols except for the first symbol of the sTTI. The sPDSCH may be demodulated using the information received from the sPDCCH, the sPDSCH may be assigned a terminal specific reference signal, and the terminal may perform channel estimation and measurement on the sPDSCH using the terminal specific reference signal.

The sCRS can only be transmitted in the first symbol of each sTTI. Unlike the existing LTE system, sCRS can be transmitted from some antenna ports of all base station antenna ports. That is, the number of antenna ports to which sCRS is allocated is reduced. On the other hand, a terminal-specific reference signal may be transmitted in the remaining symbols except for the first symbol in each sTTI, and the terminal-specific reference signal may be allocated to all antenna ports of the base station. sCRS is used for demodulation of sPDCCH and sPHICH and can also be used for SINR measurement for scheduling of downlink sub-carrier (SCC0). The measurement result in the bandwidth of the downlink sub-element carrier wave can be transmitted through the uplink element carrier wave.

In the initial access step between the UE and the BS, the BS performs a random access procedure using the legacy TTI on the downlink primary carrier (PCC), and after establishing a connection between the UE and the BS, The resource allocation is commanded by the bandwidth allocated to the link sub-element carrier wave SCC0, and the resource allocation information within the sTTI at the downlink sub-carrier (SCC0) can be transmitted to the terminal through the sPDCCH.

The time synchronization between the legacy TTI in the downlink primary carrier (PCC) and the sTTI in the downlink sub-carrier (SCC0) is performed and the downlink sub-carrier (SCC0) at the boundary of the legacy TTI of the downlink primary carrier (PCC) ) And a L1 control command may be transmitted. Control from the downlink main carrier wave (PCC) to the downlink sub carrier wave (SCCO) is performed based on the subframe in the downlink main carrier wave (PCC).

5 is a diagram illustrating an example of a downlink sub-frame of the low-delay system according to Table 2 and Table 3. FIG.

Referring to FIG. 5, the downlink sub-frame of the downlink sub-element carrier wave SCC0 may include four sub-slots operating in units of sTTI. As shown in Table 2 and Table 3, one sub-slot in the sub-element carrier may include 12 short symbols, and may be divided into a control area and a data area in the time domain. The control region may comprise one short symbol. SPDCCH, sPHICH, and sPCFICH are allocated to the control region, and the sPDSCH can be allocated to the data region.

FIG. 6 is a diagram illustrating an example of a UL subframe of the low-delay system according to Table 1. FIG.

Referring to FIG. 6, the uplink subframe of the uplink primary carrier (PCC) may be divided into a control region and a data region in the frequency domain. The control region is located at both ends of the system bandwidth and is assigned a Physical Uplink Control Channel (PUCCH) (not shown) for transmitting uplink control information. PUCCH carries various kinds of control information according to the format. PUCCH Format 1 carries a Scheduling Request. PUCCH formats 1a and 1b carry ACK / NACK, and PUCCH format 2 carries a modulated CQI (Channel Quality Indicator). A data area is assigned a Physical Uplink Shared Channel (PUSCH) for data transmission. And a Physical Random Access Channel (PRACH) may be allocated over the time domain. The PRACH transmits a random access preamble. As described above, the random access preamble through the PRACH in the random access procedure can be transmitted through the uplink main carrier (PCC). A sounding reference signal (SRS) may be transmitted through a symbol located at the last position in one subframe. The SRSs of the UEs transmitted through the last symbol of the same subframe may be classified according to the frequency position and the sequence.

The uplink sub-frame of the uplink sub-element carrier wave SCC0 may include four sub-slots operating in units of sTTI. Each sub-slot is assigned a low-delay uplink physical channel that performs the same function as the PUCCH and PUSCH. The PUCCH and the PUSCH used in the uplink sub-element carrier (SCC0) are referred to as sPUCCH and sPUSCH, respectively. Also, the SRS used in the sub-element carrier (SCC0) is referred to as sSRS.

As shown in Table 1, one sub-slot may include six short symbols, and may be divided into a control region and a data region in the frequency domain. SPUCCH is allocated to the control region, and sPUSCH is allocated to the data region. The sPUSCH is allocated resources through the DCI of the sPDCCH. The sSRS can be transmitted through the last symbol of the uplink subframe in the same manner as the SRS of the main carrier and is used for grasping the channel characteristics of the uplink resource of the uplink sub carrier (SCC0).

The uplink resources of the uplink sub-element carrier wave SCC0 are allocated through the downlink main carrier wave, and the uplink synchronization and the initial connection between the base station and the terminal can be performed through the uplink main carrier wave.

FIG. 7 is a diagram illustrating an example of an uplink sub-frame of the low-delay system according to Tables 2 and 3. FIG.

Referring to FIG. 7, the uplink sub-frame of the uplink sub-element carrier wave SCC0 may include four sub-slots operating in units of sTTI. As shown in Tables 2 and 3, one sub-slot in the sub-carrier (SCC0) may include twelve short symbols, and may be divided into a control region and a data region in the frequency domain. SPUCCH is allocated to the control region, and sPUSCH is allocated to the data region. And sSRS may be transmitted through the last symbol of the uplink subframe.

8 is a diagram illustrating a low-delay transmission method according to an embodiment of the present invention.

Referring to FIG. 8, the base station 100 periodically broadcasts low-latency information to all terminals 200 in a cell (S810). The low-delay information may include information on the sub-carrier that supports low delay. The information on the sub-carrier supporting the low delay may include the carrier frequency, the number of symbols, the sub-carrier interval, the sampling rate, the system bandwidth, and the number of transmit antennas used in the low-delay mode.

When the terminal 200 is connected to the base station 100 through the initial access procedure, the terminal 200 receives the low-delay information broadcast by the base station 100 to support the low-delay terminal in the cell.

The base station 100 recognizes that the terminal 200 is a low delay terminal capable of performing a low delay service through the terminal information transmitted from the terminal 200 in the initial access and performs scheduling for low delay data transmission / (S820).

The base station 100 transmits uplink and downlink control information and downlink data through a downlink sub slot transmitted in units of sTTI shown in FIGS. 4 and 5 (S830). The uplink and downlink control information may be transmitted through the sPDCCH, and the downlink data may be transmitted through the sPDSCH. The downlink control information may include information on the resource location and frequency hopping information of the sPDSCH in the downlink sub-carrier, the presence or absence of the UE-specific reference signal, the number of antennas, the number of layers, and the procoding matrix. Also, the uplink control information may include uplink resource allocation information, uplink link power control, uplink transmission antennas, number of layers, and precoding information in the uplink sub-carrier.

The terminal 200 acquires the uplink and downlink control information and the downlink data through the downlink sub slot (S840).

In operation S850, the UE 200 may transmit the uplink control information and the uplink data through the uplink sub slot in the uplink sub-carrier using the uplink control information.

In this way, the base station 100 can allocate resources of the low-delay physical channel while supporting a low-delay service suitable for the terminal 200. [

Meanwhile, the terminal 200 can use a low delay mode only in a specific area, and the terminal 200 that has entered a specific area can request a low delay connection with the base station 100 in a low delay mode. In this way, it is possible to save time in entering the low delay mode between the base station 100 and the terminal 200.

9 is a diagram illustrating a low-delay transmission method according to another embodiment of the present invention.

9, when the terminal 200 is connected to the base station 100, the terminal 200 receives low-delay information broadcast from the base station 100 (S910).

The terminal 200 for operating in the low delay mode transmits a low delay connection request to the base station 100 (S920).

The base station 100 receiving the low-delay connection request can perform scheduling for low-delay data transmission / reception with the terminal 200 (S930).

Next, the base station 100 transmits the uplink and downlink control information and the downlink data through the downlink sub slot transmitted in units of sTTI shown in FIGS. 4 and 5 (S940).

The terminal 200 acquires uplink and downlink control information and downlink data through a downlink sub slot (S950).

In operation S960, the UE 200 may transmit the uplink control information and the uplink data through the uplink sub slot in the uplink sub-carrier using the uplink control information.

10 is a diagram illustrating a low-delay transmission method according to another embodiment of the present invention.

Referring to FIG. 10, when the terminal 200 is connected to the base station 100, the terminal 200 receives low delay information broadcasted from the base station 100 (S1010).

The base station 100 recognizes that the terminal 200 is a low-delay terminal capable of low-delay service and performs scheduling for low-delay data transmission and reception with the terminal 200 (S1020).

The base station 100 transmits the information of the sub-carrier wave supporting the low delay to the terminal 200 in the downlink main carrier wave. The UE 200 can operate in a low delay mode on a subcarrier supporting low delay based on subcarrier information that supports low delay.

Specifically, the base station 100 transmits a Control Channel Element (CCE) index and size information of a common DCI (Downlink Control Information) format of the sPDCCH on the PDCCH of the legacy frame in the downlink main carrier wave, CCE index and size information to the terminal 200 (S1030). The CCE indicates the unit of transmission resource that is the basic resource when the DCI is transmitted through the PDCCH. One CCE may be composed of nine REGs (Resource Element Groups), and one REG may be composed of four REs (Resource Elements).

In the legacy LTE system, the PDCCH is divided into a common DCI region and a UE-specific DCI region. The common DCI indicates a DCI format commonly applied to all UEs in a cell, and the UE-specific DCI format indicates a DCI format applied to a specific UE. The sPDCCH can also be divided into a common DCI domain and a UE-specific DCI domain similar to the PDCCH. The resource allocation information of the sPUCCH may be transmitted periodically or aperiodically through the downlink main carrier.

The REG index of the common DCI region in the sPDCCH can be changed every sTTI. After the UE-specific DCI area is also allocated for each UE, the index of the REG may be changed for each sTTI, and the control from the downlink main carrier to the downlink sub carrier may be started based on the sub frame in the downlink main carrier .

In this manner, the base station 100 transmits the sPDCCH resource position from the downlink main carrier to the terminal 200 through the control information, so that the terminal 200 can transmit the sPDCCH resource position of the terminal 200 transmitted through the sPDCCH Unlike the PDCCH demodulation of the downlink main carrier wave with respect to the control information, blind detection may not be performed.

Also, the sPDCCH may be detected using the RNTI value like the PDCCH of the downlink main carrier after demodulating the sPCFICH and detecting the number of symbols allocated to the sPDCCH.

Next, the base station 100 transmits uplink and downlink control information and downlink data through a downlink sub slot transmitted in units of sTTI shown in FIGS. 4 and 5 (S1040).

The UE 200 demodulates the sPDCCH based on the CCE index and size information of the DCI format of the sPDCCH, demodulates the downlink data using the control information in the sPDCCH, and transmits the uplink and downlink control information and the downlink control information The downlink data is acquired (S1050).

Also, the UE 200 may transmit the uplink control information and the uplink data through the uplink sub slot in the uplink sub-carrier using the uplink control information (S1060).

In this manner, the terminal 200 operating in the low delay mode can request the low delay connection release in the sub-carrier to suspend the low delay mode and can request the low delay connection release through the main carrier.

11 to 14 are diagrams illustrating a method of terminating a low-delay service according to an embodiment of the present invention.

Referring to FIG. 11, when the base station 100 determines to terminate the low-delay service (S1110), the base station 100 requests the terminal 200 operating in the low-delay mode to release the low-delay connection through the control information of the sPDCCH (S1120).

When the terminal 200 receives the low-delay connection release request, the terminal 200 ends the low-delay mode on the sub-carrier. The terminal 200 that has terminated the low delay mode can request a scheduling request (SR) from the base station 100 on the uplink main carrier or receive the paging information from the base station 100 and switch to the connection mode within the main carrier have.

Alternatively, as shown in FIG. 12, the terminal 200 operating in the low delay mode on the sub-element carrier may request the base station 100 to release the low-delay connection through the control information of the sPUCCH (S1210).

When the base station 100 receives the low-delay connection release request from the terminal 200, the base station 100 terminates the low-delay service (S1220). As described above, the terminal 200 that has terminated the low-delay mode requests SR (Scheduling request) from the base station 100 on the main carrier or receives paging information from the base station 100, You can switch.

13, when the base station 100 determines to end the low-delay service (S1310), the base station 100 notifies the terminal 200 operating in the low-delay mode of the downlink sub-carrier by using control information of the PDCCH of the legacy sub- Delay connection release request (S1320).

When the terminal 200 receives the low-delay connection release request, the terminal 200 ends the low-delay mode on the sub-carrier.

14, the terminal 200 operating in the low delay mode on the sub-element carrier can request the base station 100 to release the low-delay connection through the control information of the PUCCH of the legacy sub-frame in the main carrier wave (S1410).

When the base station 100 receives the low-delay connection release request from the terminal 200, the base station 100 terminates the low-delay service (S1420).

15 is a diagram illustrating a low-delay transmission apparatus of a base station according to an embodiment of the present invention.

15, the low-delay transmission apparatus 1500 of the base station 100 includes a processor 1510, a transceiver 1520, and a memory 1530. [

The processor 1510 may perform the functions of the base station 100 described with reference to FIGS. The processor 1510 allocates the main carrier wave and the at least one sub-carrier wave to be used by the MS and can perform a resource allocation function for the physical channel in the main carrier wave and the sub-carrier wave. The processor 1510 may support a low-delay mode of the UE and may allocate a sub-carrier for low-delay support for the low-delay mode of the UE.

The transceiver 1520 is connected to the processor 1510 to transmit and receive a radio signal to and from the terminal. The transceiver 1520 may include a baseband processor (not shown) for each elementary carrier for processing the radio signal of each elementary carrier.

The memory 1530 stores instructions for execution in the processor 1510 or temporarily stores the instructions loaded from the storage device (not shown), and the processor 1510 stores the instructions in the memory 1530 Execute the loaded command.

The processor 1510 and the memory 1530 are connected to each other via a bus (not shown), and an input / output interface (not shown) may be connected to the bus. At this time, a transceiver 1520 is connected to the input / output interface, and peripheral devices such as an input device, a display, a speaker, and a storage device may be connected.

16 is a diagram illustrating a low-delay transmission apparatus of a terminal according to an embodiment of the present invention.

16, the low-delay transmission apparatus 1600 of the terminal 200 includes a processor 1610, a transceiver 1620, and a memory 1630. [

The processor 1610 may perform the functions of the terminal 200 described with reference to FIGS. The processor 1610 allocates a main carrier wave and at least one sub-element carrier wave from the base station and transmits and receives data to and from the base station based on the resource allocation information for the physical channel in the main carrier wave and the sub-carrier wave. In particular, the processor 1610 may operate in a low delay mode based on the resource allocation information of the sub-carrier for low support.

The transceiver 1620 is coupled to the processor 1610 to transmit and receive radio signals to and from the base station. The transceiver 1620 may include a baseband processor (not shown) for each carrier of an element for processing the radio signal of each elementary carrier.

The memory 1630 stores instructions for executing in the processor 1610 or temporarily stores the instructions loaded from the storage device (not shown), and the processor 1610 stores the instructions in the memory 1630 Execute the loaded command.

The processor 1610 and the memory 1630 are connected to each other via a bus (not shown), and an input / output interface (not shown) may be connected to the bus. At this time, a transceiver 1620 is connected to the input / output interface, and peripheral devices such as an input device, a display, a speaker, and a storage device may be connected.

The embodiments of the present invention are not limited to the above-described apparatuses and / or methods, but may be implemented by a program for realizing functions corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded. The embodiments can be easily implemented by those skilled in the art from the description of the embodiments described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (20)

A low-delay transmission method in a base station,
Supporting a low delay mode of a terminal over a legacy downlink subframe transmitted in a first TTI (Transmission Time Interval) unit on a downlink main carrier, and
Transmitting control information and low-delay downlink data to a terminal operating in the low-delay mode through a downlink sub slot transmitted in a second TTI unit on a downlink sub-carrier carrier
/ RTI > The method of claim 1,
Wherein the second TTI unit is shorter than the first TTI unit. The method of claim 1,
Wherein a sampling rate in the downlink sub-element carrier is set to an integral multiple of a sampling rate in the downlink sub-carrier, the sub-carrier spacing and the system bandwidth in the downlink sub-carrier are respectively a sub- Wherein the transmission rate is set to an integral multiple of the system bandwidth. The method of claim 1,
The time length of the legacy downlink subframe includes a plurality of downlink sub slots, each of the plurality of downlink sub slots includes a plurality of short symbols,
Wherein the transmitting comprises assigning a cell specific reference signal to a first one of the plurality of short symbols. 5. The method of claim 4,
Wherein the transmitting further comprises assigning a UE-specific reference signal to the remaining symbols except for the first symbol among the plurality of short symbols. The method of claim 1,
Transmitting the synchronization signal and the system information through the downlink main carrier wave
Lt; / RTI > The method of claim 1,
Wherein the step of supporting comprises transmitting low-delay information through a control channel of the legacy downlink sub-frame,
Wherein the low delay information comprises at least one of a carrier frequency of a sub-carrier, a number of symbols in the second TTI unit, a sub-carrier interval, a sampling rate, and a system bandwidth. The method of claim 1,
Transmitting a low delay connection release requesting off of the low delay mode of the terminal through the legacy downlink subframe or the downlink subframe;
Lt; / RTI > The method of claim 1,
Receiving a low delay connection release informing the UE of a low delay mode through a legacy uplink subframe transmitted in the first TTI unit or an uplink sub slot transmitted in the second TTI unit from the terminal
Lt; / RTI > The method of claim 1,
Receiving control information and low-delay uplink data from the UE through an uplink sub slot transmitted in the second TTI unit on an uplink sub-carrier carrier
Lt; / RTI > 11. The method of claim 10,
Wherein the time length of the legacy uplink subframe transmitted in the first TTI unit includes a plurality of uplink sub slots, each of the plurality of uplink sub slots includes a plurality of short symbols,
Wherein the receiving comprises receiving a SRS (Sounding Reference Signal) through a last short symbol of a last uplink sub-slot of the plurality of uplink sub-slots. A low-delay transmission method in a terminal,
Receiving low-delay information for a low-delay mode of the UE through a legacy downlink sub-frame transmitted in a first transmission time interval (TTI) unit on a downlink main carrier from the base station, and
Acquiring control information and low-delay downlink data through a sub-slot of a downlink transmitted in a second TTI unit on a downlink sub-carrier using the low-delay information;
/ RTI > The method of claim 12,
Transmitting control information and low-delay uplink data to the base station through an uplink sub slot transmitted on the uplink sub-carrier by the second TTI unit
Lt; / RTI > The method of claim 13,
Wherein the step of transmitting the control information and the low-delayed uplink data to the base station comprises the step of transmitting the control information and the low-delayed uplink data to the base station in the last uplink sub-slot of the plurality of uplink sub-slots included in the time length of the legacy uplink sub- And transmitting the SRS (Sounding Reference Signal) via a short symbol. The method of claim 12,
Wherein the time length corresponding to the legacy downlink sub-frame includes a plurality of downlink sub-slots. The method of claim 12,
Wherein a sampling rate in the downlink sub-element carrier is set to an integral multiple of a sampling rate in the downlink sub-carrier, the sub-carrier spacing and the system bandwidth in the downlink sub-carrier are respectively a sub- Wherein the transmission rate is set to an integral multiple of the system bandwidth. The method of claim 12,
Wherein the low delay information comprises at least one of a carrier frequency of a sub-carrier, a number of symbols in the second TTI unit, a sub-carrier interval, a sampling rate, and a system bandwidth. The method of claim 12,
The obtaining step
Receiving position and size information of a common DCI (Downlink control information) region of the control channel in the downlink sub slot from the base station and the UE-specific DCI location and size information, and
And receiving a common DCI and a UE-specific DCI based on location and size information of the common DCI region and UE-specific DCI location and size information. As a low-delay transmission device,
And performs scheduling for data transmission in a first TTI (Transmission Time Interval) unit, performs scheduling for data transmission in a second TTI unit on a sub-carrier, and performs scheduling for data transmission on a sub- A processor for performing resource allocation for uplink and downlink physical channels, and
A transceiver for transmitting data and uplink and downlink resource allocation information through the main carrier wave or the sub-
/ RTI >
Wherein the second TTI is shorter than the first TTI. 20. The method of claim 19,
The time length of one subframe includes a plurality of sub-slots,
Wherein the first TTI unit is set to a time length of the one subframe, the second TTI is set to a time length of one subframe,
Wherein the processor allocates a cell-specific reference signal (CRS) in a downlink to a first short symbol among a plurality of short symbols in each sub-slot.

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