KR20180090940A - Apparatus and method of multiple sTTI-based scheduling in a short TTI frame structure - Google Patents

Abstract

In the present proposal, a specific indexing method of an sTTI and a scheduling method based on the same are presented. Specifically, a multiple sTTI-based scheduling method is also described in the scheduling. The multiple sTTI-based scheduling method in a short TTI frame includes the steps of: resetting sTTI indexing in a legacy subframe unit; performing the sTTI indexing based on the modulo 3x in case of a 2-symbol sTTI; and performing the sTTI indexing based on modulo x in case of a 7-symbol sTTI.

Description

[0001] The present invention relates to a scheduling method based on multiple sTTIs in a short TTI frame,

The present invention proposes a specific method for the sTTI indexing method and the multiple sTTI-based scheduling in the 3GPP LTE / LTE-A system.

In one aspect, the present embodiments provide a method for multiple sTTI-based scheduling in a Short TTI frame, comprising: resetting sTTI indexing in units of legacy subframes; performing sTTI indexing based on modulo 3x for 2-symbol sTTI; And performing sTTI indexing based on modulo x for 7-symbol sTTI.

1 is a diagram illustrating eNB and UE processing delays and HARQ RTT.
2 shows a resource mapping per PRB in one subframe.
3 shows a legacy PUCCH uplink structure.
4 is a conceptual diagram of the configuration of a Legacy PUCCH.
5 is a conceptual diagram of the DL 2-symbol sTTI configuration.
6 is a diagram illustrating an example of a UL 2-symbol sTTI configuration.
7 is a diagram illustrating an example of sTTI indexing according to measure 1-1 in a 2-symbol sTTI structure.
8 is a diagram illustrating an example of sTTI indexing according to measure 1-2 in a 2-symbol sTTI structure.
9 is a diagram showing an example of sTTI indexing according to measures 1-3 in a 2-symbol sTTI structure.
FIG. 10 is a diagram illustrating an example of sTTI indexing according to methods 1-4 in a 2-symbol sTTI structure.
11 is a conceptual diagram of applying a shared DMRS in a 2-symbol UL sTTI structure.
FIG. 12 is a diagram illustrating a configuration of a base station according to another embodiment.
13 is a diagram illustrating a configuration of a user terminal according to another embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Herein, the MTC terminal may mean a terminal supporting low cost (or low complexity) or a terminal supporting coverage enhancement. In this specification, the MTC terminal may mean a terminal supporting low cost (or low complexity) and coverage enhancement. Alternatively, the MTC terminal may refer to a terminal defined in a specific category for supporting low cost (or low complexity) and / or coverage enhancement.

In other words, the MTC terminal in this specification may mean a newly defined 3GPP Release-13 low cost (or low complexity) UE category / type for performing LTE-based MTC-related operations. Alternatively, the MTC terminal may support enhanced coverage over the existing LTE coverage or a UE category / type defined in the existing 3GPP Release-12 or lower that supports low power consumption, or a newly defined Release-13 low cost low complexity UE category / type.

The wireless communication system in the present invention is widely deployed to provide various communication services such as voice, packet data and the like. A wireless communication system includes a user equipment (UE) and a base station (BS, or eNB). The user terminal in this specification is a comprehensive concept of a terminal in wireless communication. It is a comprehensive concept which means a mobile station (MS), a user terminal (UT), an SS (User Equipment) (Subscriber Station), a wireless device, and the like.

A base station or a cell generally refers to a station that communicates with a user terminal and includes a Node-B, an evolved Node-B (eNB), a sector, a Site, a BTS A base transceiver system, an access point, a relay node, a remote radio head (RRH), a radio unit (RU), and a small cell.

That is, the base station or the cell in this specification is interpreted as a comprehensive meaning indicating a partial region or function covered by BSC (Base Station Controller) in CDMA, NodeB in WCDMA, eNB in LTE or sector (site) And covers various coverage areas such as megacell, macrocell, microcell, picocell, femtocell and relay node, RRH, RU, and small cell communication range.

Since the various cells listed above exist in the base station controlling each cell, the base station can be interpreted into two meanings. i) the device itself providing a megacell, macrocell, microcell, picocell, femtocell, small cell in relation to the wireless region, or ii) indicating the wireless region itself. i indicate to the base station all devices that are controlled by the same entity or that interact to configure the wireless region as a collaboration. An eNB, an RRH, an antenna, an RU, an LPN, a point, a transmission / reception point, a transmission point, a reception point, and the like are exemplary embodiments of a base station according to a configuration method of a radio area. ii) may indicate to the base station the wireless region itself that is to receive or transmit signals from the perspective of the user terminal or from a neighboring base station.

Therefore, a base station is collectively referred to as a base station, collectively referred to as a megacell, macrocell, microcell, picocell, femtocell, small cell, RRH, antenna, RU, low power node do.

Herein, the user terminal and the base station are used in a broad sense as the two transmitting and receiving subjects used to implement the technical or technical idea described in this specification, and are not limited by a specific term or word. The user terminal and the base station are used in a broad sense as two (uplink or downlink) transmitting and receiving subjects used to implement the technology or technical idea described in the present invention, and are not limited by a specific term or word. Here, an uplink (UL, or uplink) means a method of transmitting / receiving data to / from a base station by a user terminal, and a downlink (DL or downlink) .

There are no restrictions on multiple access schemes applied to wireless communication systems. Various multiple access schemes such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), OFDM-FDMA, OFDM- Can be used. An embodiment of the present invention can be applied to asynchronous wireless communication that evolves into LTE and LTE-advanced via GSM, WCDMA, and HSPA, and synchronous wireless communication that evolves into CDMA, CDMA-2000, and UMB. The present invention should not be construed as limited to or limited to a specific wireless communication field and should be construed as including all technical fields to which the idea of the present invention can be applied.

A TDD (Time Division Duplex) scheme in which uplink and downlink transmissions are transmitted using different time periods, or an FDD (Frequency Division Duplex) scheme in which they are transmitted using different frequencies can be used.

In systems such as LTE and LTE-advanced, a standard is constructed by configuring uplink and downlink based on a single carrier or carrier pair. The uplink and the downlink are divided into a Physical Downlink Control Channel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel, a Physical Uplink Control CHannel (PUCCH), an Enhanced Physical Downlink Control Channel (EPDCCH) Transmits control information through the same control channel, and is configured with data channels such as PDSCH (Physical Downlink Shared CHannel) and PUSCH (Physical Uplink Shared CHannel), and transmits data.

On the other hand, control information can also be transmitted using EPDCCH (enhanced PDCCH or extended PDCCH).

In this specification, a cell refers to a component carrier having a coverage of a signal transmitted from a transmission point or a transmission point or transmission / reception point of a signal transmitted from a transmission / reception point, and a transmission / reception point itself .

The wireless communication system to which the embodiments are applied may be a coordinated multi-point transmission / reception system (CoMP system) or a coordinated multi-point transmission / reception system in which two or more transmission / reception points cooperatively transmit signals. antenna transmission system, or a cooperative multi-cell communication system. A CoMP system may include at least two multipoint transmit and receive points and terminals.

The multi-point transmission / reception point includes a base station or a macro cell (hereinafter referred to as 'eNB'), and at least one mobile station having a high transmission power or a low transmission power in a macro cell area, Lt; / RTI >

Hereinafter, a downlink refers to a communication or communication path from a multipoint transmission / reception point to a terminal, and an uplink refers to a communication or communication path from a terminal to a multiple transmission / reception point. In the downlink, a transmitter may be a part of a multipoint transmission / reception point, and a receiver may be a part of a terminal. In the uplink, the transmitter may be a part of the terminal, and the receiver may be a part of multiple transmission / reception points.

Hereinafter, a situation in which a signal is transmitted / received through a channel such as PUCCH, PUSCH, PDCCH, EPDCCH, and PDSCH is expressed as 'PUCCH, PUSCH, PDCCH, EPDCCH and PDSCH are transmitted and received'.

In the following description, an indication that a PDCCH is transmitted or received or a signal is transmitted or received via a PDCCH may be used to mean transmitting or receiving an EPDCCH or transmitting or receiving a signal through an EPDCCH.

That is, the physical downlink control channel described below may mean a PDCCH, an EPDCCH, or a PDCCH and an EPDCCH.

Also, for convenience of description, EPDCCH, which is an embodiment of the present invention, may be applied to the portion described with PDCCH, and EPDCCH may be applied to the portion described with EPDCCH according to an embodiment of the present invention.

Meanwhile, the High Layer Signaling described below includes RRC signaling for transmitting RRC information including RRC parameters.

The eNB performs downlink transmission to the UEs. The eNB includes a physical downlink shared channel (PDSCH) as a main physical channel for unicast transmission, downlink control information such as scheduling required for reception of a PDSCH, A physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission in a Physical Uplink Shared Channel (PUSCH). Hereinafter, the transmission / reception of a signal through each channel will be described in a form in which the corresponding channel is transmitted / received.

[Latency reduction in RAN1 ]

The Latency reduction Study Item was approved at RAN plenary # 69 meeting [1]. The main purpose of latency reduction is to standardize shorter TTI operations to foster TCP throughput [2]. For this purpose, performance verification for short TTI has already been performed in RAN2 [2].

Potential impacts and studies related to RAN1 are performed in the following ranges [1]:

o Assessment of impact and performance of TTI lengths between 0.5ms and one OFDM symbols, taking into account the impact of reference signals and physical layer control signaling

o backwards compatibility shall be preserved (thus allowing normal operation of pre- Rel 13 UEs on the same carrier);

Latency reduction can be achieved by the following physical layer techniques:

- short TTI

- reduced processing time in implementation

- new frame structure of TDD

Additional agreements at the 3GPP RAN WG1 # 84 meeting are as follows.

Agreements:

● Following design assumptions are considered:

   o No shortened TTI spans over subframe boundary

   o At least for SIBs and paging, PDCCH and legacy PDSCH are used for scheduling

● The potential specific impacts for the followings are studied

   o UE is expected to receive a SDSCH at least for downlink unicast

      ■ sPDSCH refers PDSCH carrying data in a short TTI

   o UE is expected to receive PDSCH for downlink unicast

      ■ FFS whether a UE is expected to receive both PDSCH and PDSCH for downlink unicast simultaneously

o FFS: The number of supported short TTIs

o If the number of supported TTIs is more than one,

Agreements:

● Following design assumptions are used for the study

o From eNB perspective, existing non-sTTI and sTTI can be FDMed in the same subframe in the same carrier

      ■ FFS: Other multiplexing method (s) with existing non-sTTI for UE supporting latency reduction features

Agreements:

● In this study, the following aspects are assumed in RAN1.

o PSS / SSS, PBCH, PCFICH and PRACH, Random access, SIB and Paging procedures are not modified.

● Following aspects are further studied in the next RAN1 meeting

o Note: The study is not limited to them.

o Design of sPUSCH DM-RS

      ■ Alt.1: DM-RS symbol shared by multiple short-TTIs within the same subframe

      ■ Alt.2: DM-RS contained in each sPUSCH

o HARQ for SPUSCH

      ■ Whether / how to realize asynchronous and / or synchronous HARQ

o sTTI operation for Pcell and / or SCells by (e) CA in addition to non (e) CA case

Basically, in the average down-link latency calculation, the latency is calculated according to the following procedure [3].

The following is the same approach as in section B.2.1 in 3GPP TR 36.912, the LTE U-plane one-way latency for a scheduled UE consisting of fixed node processing delays and 1 TTI duration for transmission as shown in Figure 1 below. Assuming the processing times can be scaled by the same factor of TTI reduction keeping the same number of HARQ processes, the one way latency can be calculated as

D = 1.5 TTI + 1 TTI + 1.5 TTI UE + n * 8 TTI (HARQ retransmissions)

    = (4 + n * 8) TTI.

Considering a typical case where there would be 0 or 1 retransmission, and assuming error probability of the first transmission to be p, the delay is given by

D = (4 + p * 8) TTI.

So, for 0% BLER, D = 4 * TTI,

And for 10% BLER, D = 4.8 * TTI.

Average UE  initiated UL transmission latency calculation

Assume UE is in connected / synchronized mode and wants to do UL transmission, e.g., send to TCP ACK. The following table shows the steps and their corresponding contribution to the UL transmission latency. To be consistent in comparison of DL and UL, we add the eNB processing delay in the UL after the UL data is received by the eNB (step 7).

In the table above, steps 1 and 4 and half of the step 5 are assumed to be due to SR, and the rest is assumed to be shown in Table 4

Resource mapping of short TTI  [3]

In Figure 2 the resource map above is the legacy resource mapping per PRB in one subframe, considering 2 Antenna ports and 2 OFDM symbols control field. In Figure 2 the resource map below is the short TTI resource mapping, considering 2 OFDM symbols used for the control field in order to ensure the backward compatibility. The loss rates (L _legacy , eg 5% - 50%) of the PHY layer are short TTI duration are assumed.

TBS Calculation of short TTI

According to the present invention, the PDSCH is calculated as follows:

For different short TTI duration, The TBS of short TTI PDSCH is calculated as the following table:

[Existing PUCCH ]

The DL control channel through which the UE sends a response to the PDSCH reception is the PUCCH. The UE uses various formats of PUCCH format to transmit Ack / Nack and CQI information for the downlink data channel to the eNB.

The conventional LTE / LTE-A frame structure (TTI = 1 ms = 14 OFDM symbols) performs slot based PUCCH hopping as shown in FIG. This PUSCH hopping increases the frequency diversity of the PUCCH and consequently increases the coverage of the PUCCH. This is because basically the same signal or one information sequence is transmitted through different frequency bands, so that there is a gain to obtain diversity.

In transmitting an A / N from an existing PUCCH, resource allocation is applied by OCC (spreading) + CS (cyclic shift) on the basis of format 1a and 1b. As shown in FIG. 2, the existing PUCCH is set to 3 symbols RS and 4 symbols A / N on a slot basis.

In this proposal, CS-based A / N multiplexing resource allocation of the Zadoff-Chu (ZC) sequence excluding the existing OCC is proposed considering that the number of symbols of the sPUCCH is reduced. Unlike the existing structure, OCC spreading is not used at this time.

에서 정의되는 cyclic shift

값으로 정의된다. (TS 36.211참조)The ZC sequence is basically the RS

Cyclic shift

Value. (See TS 36.211)

In this proposal, the following basic structure is assumed for the sPUCCH A / N configuration excluding OCC.

Here, PUCCH format 1a / b performs dynamic resource allocation. Basically, the following dynamic allocation is performed based on the CCE index of the scheduled PDCCH.

은 하향 자원 할당에 사용된 DCI 전송에 사용된 PDCCH의 lowest CCE index

와 상위 레이어서 전송되는

에 의해서 결정된다. 여기에서

은 결국 PUCCH format 1a/1b가 다른 PUCCH format 2/3/4 등과 분리될 수 있도록 설정된 일종의 shift 값을 위미한다.Here, the PUCCH resource index for Ack / Nack

The lowest CCE index of the PDCCH used for the DCI transmission used for the downlink resource allocation

And the upper layer

. From here

The PUCCH format 1a / 1b is set as a kind of shift value set so that it can be separated from other PUCCH format 2/3/4 and so on.

The work scope of the recently shortened TTI Work item and the 3GPP RAN WG1 # 86 meeting were further agreed upon as follows.

For Frame structure type 1: [RAN1, RAN2, RAN4]

Specify support for a transmission duration based on 2-symbol sTTI and 1-slot sTTI for sPDSCH/sPDCCH

Specify support for a transmission duration based on 2-symbol sTTI and 1-slot sTTI for sPDSCH / sPDCCH

Specify support for a transmission duration based on 2-symbol sTTI, 4-symbol sTTI, and 1-slot sTTI for sPUCCH/sPUSCH

2-symbol sTTI, 4-symbol sTTI, and 1-slot sTTI for sPTICH / sPTCH

 o Down-selection is not precluded

Study any impact on CSI feedback and processing time, and if needed, specify necessary modifications (not before RAN1 #86bis)

Study any impact on CSI feedback and processing time, and if necessary, specify necessary modifications (not before RAN1 # 86bis)

Agreement:

For FS1,2&3, a minimum timing n+3 is supported for UL grant to UL data and for DL data to DL HARQ for UEs capable of operating with reduced processing time with only the following conditions:

For FS1, 2 & 3, a minimum timing n + 3 is supported for UL grant to UL data and DL data to DL HARQ for UEs capable of operating with reduced processing time with only the following conditions:

A maximum TA is reduced to x ms, where x <= 0.33ms (exact value FFS);

A maximum TA is reduced to x ms, where x < = 0.33ms (exact value FFS);

At least when scheduled by PDCCH

At least when scheduled by PDCCH

For FS2, new DL HARQ and UL scheduling timing relations will be defined

For FS2, new DL HARQ and UL scheduling timing relations will be defined

Details FFS

Details FFS

FFS:

FFS:

Possible minimum timing of n+2 TTI

Possible minimum timing of n + 2 TTI

FFS max TA in this case

FFS max TA in this case

FFS what other restrictions (if any) on when reduced processing times of n+2 could be applied

FFS what other restrictions (if any) on when reduced processing times of n + 2 could be applied

Possibility of scheduling by EPDCCH.

Possibility of scheduling by EPDCCH.

Agreement:

Reduced processing time(s) are RRC configured for the UE

Reduced processing time (s) are RRC configured for the UE

Working assumption: A mechanism for dynamic fallback to legacy processing timings (n+4) is supported

Working assumption: A mechanism for dynamic fallback to legacy processing timings (n + 4) is supported

- Details FFS

Working assumption can be revised if it is not found to be feasible

In the 3GPP RAN1 # 85 meeting related to the DL-RS, the following matters were decided.

Agreement:

For sPDSCH based on a CRS based transmission scheme the maximum number of supported layers is 4

For sPDSCH based on a CRS based transmission scheme the maximum number of supported layers is 4

For sPDSCH based on a DM-RS based transmission scheme shall be down-selected among the following options

For sPDSCH based on a DM-RS based transmission scheme,

 - the maximum number of supported layers is 2

 - the maximum number of supported layers is 4

 - the maximum number of supported layers is 8

FFS for sPDSCH based on a DM-RS based transmission scheme it is recommended to increased PRB bundling size compared to PDSCH for at least sTTI lengths shorter than 1-slot

FFS for PDSCH based on a DM-RS based transmission scheme it is recommended to increase PRB bundling size compared to PDSCH for at least sTTI lengths shorter than 1-slot

As described above, studies on the physical layer for short TTI are underway, and there is no specific method for sTTI indexing and multiple sTTI scheduling.

In the present invention, a sTTI indexing method for short TTI frames and a UL / DL sPUSCH / s PDSCH scheduling method using multiple sTTIs are presented.

In this proposal, a specific indexing method of sTTI and a scheduling method based on it are presented. Specifically, multiple sTTI based scheduling methods are also described in the scheduling.

First, the sTTI structure has a structure similar to DL and UL based on 2-symbol and 7-symbol. Currently, this decision will be decided at 3GPP RAN1 # 88 and later meetings. Specifically, 2-symbol and 7-symbol structures are largely determined, and the slot boundary of each subframe is maintained. For example, in a 2-symbol sTTI structure, upper / lower sTTIs exist as shown in FIG. 5 and FIG.

In the present invention, a detailed method of the sTTI indexing method and the multiple sTTI scheduling method necessary for such an sTTI configuration will be described.

Method 1. Short TTI  The index is legacy subframe  Perform numbering in units.

In this proposal, we propose that the indexing method of UL / DL sTTI is performed in a specific subframe unit. That is, the index of the existing subframe is 0,1,2, ... , 9, and there are 10 subframes in total. sTTI also needs a similar indexing scheme. However, since the number of sTTI indexes varies according to the sTTI configuration, indexing corresponding to the UL / DL sTTI configuration is required. This indexing method is also important because it is used as a basic unit of retransmission and CQI reporting such as HARQ process number of sTTI.

The basic idea is to perform sTTI indexing in legacy subframes. There are two sets of sTTI values in total. 2-symbol, 7-symbol, and there are 6 sTTIs and 2 sTTIs in the legacy suframe, respectively. The sTTI indexing method for each case is as follows.

Solution 1-1. Short TTI  Indexes are single subframe  Perform numbering in units.

In this proposal, the sTTI indexing is reset in units of legacy suframes, and the sTTI index nsTTI can be expressed in units of 2-symbol and 7-symbol in the following units, respectively.

● 2-symbol sTTI config .: nsTTI = 0,1,2, ... , 5 per single subframe (based on modulo 6)

● 7-symbol sTTI config .: nsTTI = 0,1 per single subframe (based on modulo 2)

Plan 1-2. Short TTI  The index is a half radio frame (= 5 subframes ) Numbering.

In this proposal, the sTTI indexing is reset in units of legacy 5 suframes, and the sTTI index nsTTI can be expressed in units of 2-symbol and 7-symbol in the following units, respectively.

● 2-symbol sTTI config .: nsTTI = 0,1,2, ... , 29 per 5 subframes (based on modulo 30)

● 7-symbol sTTI config .: nsTTI = 0,1,2, ... , 9 per 5 subframes (based on modulo 10)

Methods 1-3. Short TTI  The index is a radio frame (= 10 subframes ) Numbering.

In this proposal, the sTTI indexing is reset in units of legacy 10 suframes, and the sTTI index nsTTI can be expressed in the following units for 2-symbol and 7-symbol, respectively.

    ● 2-symbol sTTI config .: nsTTI = 0,1,2, ... , 59 per 10 subframes (based on modulo 60)

    ● 7-symbol sTTI config .: nsTTI = 0,1,2, ... , 19 per 10 subframes (based on modulo 20)

Methods 1-4. Short TTI  The index Nx subframe  Perform numbering in units.

In the present proposal, the sTTI indexing is reset in arbitrary legacy Nx suframes units, and the sTTI index nsTTI can be expressed in the following units in the case of 2-symbol and 7-symbol, respectively.

● 2-symbol sTTI config .: nsTTI = 0,1,2, ... , 6Nx-1 per Nx subframes (based on modulo 6Nx)

● 7-symbol sTTI config .: nsTTI = 0,1,2, ... , 2Nx-1 per Nx subframes (based on modulo 2Nx)

2. Short TTI  multiple sTTI  Based scheduling.

We propose a concrete scheme for multiple sTTI scheduling in sTTI. Multiple sTTI scheduling utilizes the previously defined sTTI indexing, and can be configured in a specific unit.

In this proposal, the operation of the terminal differs from the legacy LTE because it is performed in units of sTTI, not in the existing subframe. Here, it is assumed that the sTTI information of the terminal is transmitted through the control information transmitted through the legacy PDCCH.

At this time, the eNB can set multiple sTTI scheduling through RRC signaling, and can set sTTI number, period, sTTI pattern, and the like in advance. An example of the setting is shown below.

- sTTI transmission count: For example, if this value is set to 3, it means that three 3 sTTIs are simultaneously scheduled in legacy subframe in 2-symbol sTTI at the same time

- Transmission period: This is the time interval over which multiple sTTIs are valid. Therefore, the UE can apply multiple scheduling only for a specific subframe length or a sTTI length.

- sTTI pattern: For example, if the number of sTTI transmissions in a 2-symbol sTTI structure is 3, only 3 out of 6 sTTIs should be selected and scheduled.

In this case, (OOOXXX), (XOOOXX), (XXOOOX), ... It is possible to set these sets through specific patterns such as. If all sTTIs are transmitted on a subframe basis, the value is set to the maximum number of sTTIs in the legacy suframe.

Solution 2-1. Multiple sTTI  When the scheduling information is transmitted sTTI  Specify it separately.

In this proposal, a method of selecting a control channel through which a UE transmits multiple sTTI scheduling information when multiple sTTI scheduling is performed based on the set RRC setting information will be described. The UE can use only the control information received via the legacy PDCCH for the corresponding information, and in some cases, the UE can use the control information received through the sPDCCH in the specific sTTI. Therefore, it is necessary to set the corresponding information through the RRC setting to the UE or perform a direct indication through another method.

Solution 2-2. share DMRS  Based UL multiple sTTI In the case of scheduling  certain DMRS  Enable the resource.

In this proposal, a concrete plan for UL multiple sTTI scheduling is presented. In the case of UL, the DMRS can be shared, and the position of the DMRS can be instructed to the terminal through an UL grant by dividing the position of the DMRS in its sTTI, before / after. However, in the multiple sTTI scheduling, since the same UL grant indication information is applied to various sTTIs, the following cases can be considered. Basically, it is assumed that the sPUSCH control information applied through the UL grant is transmitted based on the first UL sTTI.

- Case 1. Instructions for using DMRS in sTTI

The UE performs sPUSCH transmission using UL DMRS transmitted in each sTTI.

- Case2. Shared DMRS transmission instruction

When the UL DMRS of the first sTTI is commonly used, the DMRS designation information of the first sTTI indicates the DMRS in its sTTI, and the information indicating the previous sTTI DMRS should be transmitted to the remaining sTTIs. Conversely, when the UL DMRS of the last sTTI is commonly used, information indicating the last sTTI should be transmitted to its own UL DMRS and the remainder of the information to be referred to as a DMRS outside its sTTI.

Therefore, in this proposal, to solve this problem, multiple sPUSCH transmission using shared DMRS must transmit the sTTI location (index information, etc.) where the shared DMRS is located and the DMRS port or resource index to the UE. For example, assuming that the shared DMRS is located in sTTIO as shown in FIG. 11, the DMRS configuration information for the Multiple sPUSCH transmission can be set as follows.

- UL grant information

      ■ Resource assignment: ...

      ■ MCS level: ...

      ■ DMRS position: 00 (00: in, 01: before, 10: after)

In this case, sTTI0 can use DMRS in its own sTTI, but shared DMRS can not be used for sPTICHs of the remaining sTTIs. That is, in the multiple sTTI transmission, only the scheduling using only the DMRS located in each sTTI may be effective.

Therefore, in this proposal, we propose a scheme to transmit the configuration information of the shared DMRS port to the UE in association with the multiple sTTI scheduling so that multiple sPUSCH transmission using a specific shared DMRS is possible. Shared DMRS port information can include the sTTI position where the DMRS is located or the sTTI index and the DMRS resource number. In the Shared DMRS, the sPUSCHs transmitted by the same UE may use a single DMRS port or resource, or may use different DMRS for each sTTI sPUSCH.

The present invention proposes a specific method for the sTTI indexing method and the multiple sTTI-based scheduling in the 3GPP LTE / LTE-A system. The method can be applied to similar signals and channels as they are, Is not limited.

FIG. 12 is a diagram illustrating a configuration of a base station according to another embodiment.

12, a base station 1000 according to another embodiment includes a control unit 1010, a transmission unit 1020, and a reception unit 1030.

The controller 1010 controls the overall operation of the base station according to the sTTI indexing in the short TTI frame according to the present invention described above.

The transmitting unit 1020 and the receiving unit 1030 are used to transmit and receive signals, messages, and data necessary for carrying out the present invention to and from the terminal.

13 is a diagram illustrating a configuration of a user terminal according to another embodiment of the present invention.

13, the user terminal 1100 according to another embodiment includes a receiving unit 1110, a control unit 1120, and a transmitting unit 1130.

The receiving unit 1110 receives downlink control information, data, and messages from the base station through the corresponding channel.

In addition, the controller 1120 controls the overall operation of the terminal according to the sTTI indexing in the short TTI frame according to the present invention described above.

The transmitter 1130 transmits uplink control information, data, and a message to the base station through the corresponding channel.

The standard content or standard documents referred to in the above-mentioned embodiments constitute a part of this specification, for the sake of simplicity of description of the specification. Therefore, it is to be understood that the content of the above standard content and portions of the standard documents are added to or contained in the scope of the present invention.

Appendix

[1] Ericsson, Huawei, "New SI proposal Study on Latency Reduction Techniques for LTE", RP-150465, Shanghai, China, March 9-12, 2015.

[2] R2-155008, "TR 36.881 v0.4.0 on Study Latency reduction techniques for LTE", Ericsson (Rapporteur)

[3] R1-160927, "TR 36.881-v0.5.0 on Study Latency Reduction Techniques for LTE", Ericsson (Rapporteur)

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (1)

In a multiple sTTI based scheduling method in a Short TTI frame,
resetting sTTI indexing in units of legacy subframes;
Performing the sTTI indexing based on modulo 3x if the 2-symbol sTTI is performed; And
And performing the sTTI indexing based on modulo x if it is a 7-symbol sTTI.

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