KR102120976B1 - Method and apparatus for transmitting uplink channel in a short tti frame structure - Google Patents

Abstract

The present embodiments relate to specific operations of a terminal and a base station that transmit and receive an uplink channel in a short TTI based frame structure in a 3GPP LTE/LTE-Advanced system. According to the present embodiments, sPUCCH is configured through a method of assigning two separate CS values for each UE so that an Ack/Nack message can be transmitted without including RS in sPUCCH, and sPUSCH and SRS are in the same symbol in sTTI. By providing a specific operation method when overlapping, a specific operation method of a terminal and a base station is provided when sPUSCH and SRS are simultaneously transmitted in an sTTI frame structure.

Description

Method and apparatus for transmitting an uplink channel in a frame structure with a short transmission time interval {METHOD AND APPARATUS FOR TRANSMITTING UPLINK CHANNEL IN A SHORT TTI FRAME STRUCTURE}

The present embodiments relate to operations of a terminal and a base station for transmission and reception of an uplink channel in a 3GPP LTE/LTE-Advanced system.

Research and discussion for latency reduction in 3GPP LTE/LTE-Advanced systems are underway. The main purpose of latency reduction is to standardize the operation of shorter TTI (hereinafter referred to as'short TTI' or'sTTI') to improve TCP throughput.

To this end, RAN2 performs performance verification for short TTI, and discussions on the feasibility and performance of TTI length between 0.5ms and one OFDM symbol and maintaining backward compatibility are ongoing.

Although studies on the physical layer for such a short TTI are in progress, specific procedures for setting a short TTI-based PUCCH and transmitting and receiving sPUSCH and legacy SRS are absent.

The purpose of the present embodiments is to provide a specific operation method of a UE and a base station when transmitting/receiving an uplink control channel and an uplink data channel in a short TTI-based frame structure and simultaneously transmitting an uplink data channel and a sounding reference signal. Having

In one aspect, the present embodiments, in a method for a terminal to transmit an uplink channel in a frame structure with a short transmission time interval, receiving a downlink data from a base station through a downlink data channel with a short transmission time interval, , Transmitting the Ack/Nack for the downlink data to the base station through the uplink control channel with a short transmission time interval, and transmitting the uplink data and the sounding reference signal to the base station through the uplink data channel with a short transmission time interval. It provides a method for transmitting at least one of uplink data and a sounding reference signal through at least one of uplink data channels having a short transmission time interval included in one subframe.

In another aspect, the present embodiments provide a method in which a base station receives an uplink channel in a frame structure with a short transmission time interval, transmitting downlink data to a terminal through a downlink data channel with a short transmission time interval. , Ack/Nack for downlink data is received through an uplink control channel having a short transmission time interval, and receiving uplink data and a sounding reference signal from the terminal through an uplink data channel having a short transmission time interval. It includes a step, and provides a method for receiving at least one of uplink data and a sounding reference signal through at least one of a short transmission time interval uplink data channel included in one subframe.

In another aspect, the present embodiments include a method in which a terminal transmits an uplink channel in a frame structure with a short transmission time interval, receiving downlink data from a base station through a downlink data channel with a short transmission time interval; , Configuring the uplink control channel of the short transmission time interval including the Ack/Nack by assigning individual cyclic shift values to the Ack/Nack, and downlink data through the uplink control channel of the short transmission time interval. It provides a method comprising the step of transmitting the Ack / Nack for the base station.

In another aspect, the present embodiments provide a method in which a base station receives an uplink channel in a frame structure with a short transmission time interval, transmitting downlink data to a terminal through a downlink data channel with a short transmission time interval. , Ack/Nack for the downlink data is received through the uplink control channel of the short transmission time interval from the terminal, and the uplink control channel of the short transmission time interval assigns the individual cyclic shift values to the Ack/Nack respectively. It provides a method that is configured in an allocation manner.

According to the present embodiments, a specific scheme for setting and transmitting and receiving sPUCCH in a short TTI-based frame structure and an uplink channel transmission and reception scheme capable of solving an overlapping problem between sPUSCH and SRS symbol intervals are provided.

1 is a diagram showing eNB and UE processing delays and HARQ RTT.
2 is a diagram showing a resource mapping per PRB in one subframe.
3 is a diagram illustrating an example of an uplink channel transmission method in an sTTI-based frame structure.
4 is a diagram illustrating a conceptual diagram of transmission of sPUSCH and SRS.
5 is a diagram illustrating a conceptual diagram of SRS and legacy PUSCH allocation.
6 is a view showing a conceptual diagram of SRS protection through sPUSCH drop.
7 is a view showing a conceptual diagram of sTTI bundling.
8 is a diagram showing the configuration of a base station according to the present embodiments.
9 is a diagram showing the configuration of a user terminal according to the present embodiments.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. It should be noted that in adding reference numerals to the components of each drawing, the same components have the same reference numerals as possible even though they are displayed on different drawings. In addition, in describing the present invention, when it is determined that detailed descriptions of related well-known structures or functions may obscure the subject matter of the present invention, detailed descriptions thereof will be omitted.

In this specification, 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 that supports low cost (or low complexity) and coverage enhancement. Alternatively, in this specification, the MTC terminal may mean a terminal defined as a specific category to support low cost (or low complexity) and/or coverage enhancement.

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

The wireless communication system in the present invention is widely deployed to provide various communication services such as voice and packet data. The wireless communication system includes a user equipment (UE) and a base station (Base Station, BS, or eNB). The user terminal in the present specification is a comprehensive concept that means a terminal in wireless communication, as well as UE (User Equipment) in WCDMA and LTE, HSPA, MS (Mobile Station) in GSM, UT (User Terminal), SS It should be interpreted as a concept including (Subscriber Station) and wireless devices.

Base station or cell (cell) generally refers to a station (station) to communicate with the user terminal, Node-B (Node-B), eNB (evolved Node-B), Sector (Sector), Site (Site), BTS ( Base Transceiver System), an access point (Access Point), a relay node (Relay Node), RRH (Remote Radio Head), RU (Radio Unit), can be called in other terms such as small cells.

That is, in this specification, the base station or cell (cell) is interpreted in a comprehensive sense indicating some areas or functions covered by a base station controller (BSC) in CDMA, a NodeB in WCDMA, an eNB or sector (site) in LTE, and the like. This means that it covers all of the 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 have a base station that controls each cell, the base station can be interpreted in two ways. It may be i) a device providing a megacell, a macrocell, a microcell, a picocell, a femtocell, or a small cell in relation to the radio area, or ii) the radio area itself may be indicated. In i), all devices that provide a predetermined wireless area are controlled by the same entity, or all devices that interact to configure the wireless area in a collaborative manner are directed to the base station. ENB, RRH, antenna, RU, LPN, point, transmit/receive point, transmit point, receive point, etc., according to the configuration method of the radio area, are an embodiment of the base station. In ii), the radio area itself, which receives or transmits a signal from the perspective of the user terminal or the neighboring base station, may indicate to the base station itself.

Accordingly, megacell, macrocell, microcell, picocell, femtocell, small cell, RRH, antenna, RU, low power node (LPN), point, eNB, transmit/receive point, transmit point, receive point are collectively referred to as base stations. do.

In this specification, the user terminal and the base station are two transmission/reception subjects used to implement the technology or technical idea described herein, and are used in a comprehensive sense and are not limited by terms or words specifically referred to. The user terminal and the base station are two (Uplink or Downlink) transmitting and receiving subjects used in realizing the technology or technical idea described in the present invention and are used in a comprehensive sense and are not limited by terms or words specifically referred to. Here, the uplink (Uplink, UL, or uplink) means a method of transmitting and receiving data to the base station by the user terminal, the downlink (Downlink, DL, or downlink) transmits and receives data to the user terminal by the base station Means the way.

There are no restrictions on the multiple access technique applied to the wireless communication system. Various multiple access techniques 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-TDMA, OFDM-CDMA Can be used. One embodiment of the present invention can be applied to resource allocation such as asynchronous wireless communication evolving to LTE and LTE-advanced through GSM, WCDMA, HSPA, and synchronous wireless communication evolving to CDMA, CDMA-2000 and UMB. The present invention should not be interpreted as being limited or limited to a specific wireless communication field, and should be interpreted as including all technical fields to which the spirit of the present invention can be applied.

For uplink transmission and downlink transmission, a time division duplex (TDD) method transmitted using different times may be used, or a frequency division duplex (FDD) method transmitted using different frequencies may be used.

In addition, in systems such as LTE and LTE-advanced, a standard is configured by configuring uplink and downlink based on one carrier or a pair of carriers. The uplink and downlink are PDCCH (Physical Downlink Control CHannel), PCFICH (Physical Control Format Indicator CHannel), PHICH (Physical Hybrid ARQ Indicator CHannel), PUCCH (Physical Uplink Control CHannel), EPDCCH (Enhanced Physical Downlink Control CHannel), etc. Control information is transmitted through the same control channel, and is composed of data channels such as a physical downlink shared channel (PDSCH) and a physical uplink shared channel (PUSCH) to transmit data.

Meanwhile, control information may also be transmitted using an enhanced PDCCH (EPDCCH) or an extended PDCCH.

In this specification, a cell is a component carrier having a coverage of a signal transmitted from a transmission/reception point or a signal transmitted from a transmission/reception point or a transmission/reception point itself. Can be.

A wireless communication system to which embodiments are applied is a multi-point transmission/reception system (CoMP system) in which two or more transmission/reception points cooperate to transmit a signal, or a coordinated multi-antenna transmission method. antenna transmission system), and a cooperative multi-cell communication system. The CoMP system may include at least two multiple transmission/reception points and terminals.

The multiple transmission/reception points include at least one of a base station or a macro cell (hereinafter referred to as'eNB') and a high transmission power, which is wired and controlled by an optical cable or an optical fiber to the eNB, or a low transmission power in the macro cell area. It may be RRH.

Hereinafter, downlink means a communication or communication path from a multiple transmission/reception point to a terminal, and uplink refers to a communication or communication path from a terminal to a multiple transmission/reception point. In the downlink, the transmitter may be a part of multiple transmission/reception points, and the receiver may be a part of the 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 signals are transmitted/received through channels such as PUCCH, PUSCH, PDCCH, EPDCCH, and PDSCH is also described in the form of'transmit and receive PUCCH, PUSCH, PDCCH, EPDCCH and PDSCH'.

In addition, hereinafter, description of transmitting or receiving a PDCCH or transmitting or receiving a signal through the PDCCH may be used in a sense including transmitting or receiving an EPDCCH or transmitting or receiving a signal through the EPDCCH.

That is, the physical downlink control channel described below may mean PDCCH or EPDCCH, and are also used to include both PDCCH and EPDCCH.

In addition, for convenience of description, the EPDCCH, which is an embodiment of the present invention, may be applied to the part described with PDCCH, and the PDCCH may be applied to the part, described with EPDCCH, as an embodiment of the present invention.

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

The eNB performs downlink transmission to terminals. The eNB has a downlink control information and an uplink data channel such as a physical downlink shared channel (PDSCH), which is a main physical channel for unicast transmission, and scheduling required for receiving the PDSCH (eg For example, a physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission on a physical uplink shared channel (PUSCH) may be transmitted. Hereinafter, the transmission and reception of signals through each channel will be described as a form in which the corresponding channel is transmitted and received.

In the present invention, a specific method for the operation of a terminal and a base station for transmission and reception of a short TTI-based uplink channel in a 3GPP LTE/LTE-Advanced system is proposed. In particular, it proposes a specific operation of a terminal and a base station for setting and transmitting and receiving sPUCCH and simultaneous transmission and reception of sPUSCH and SRS.

[Latency reduction in RAN1]

The Latency reduction Study Item was approved at the 3GPP RAN plenary #69 meeting. The main purpose of latency reduction is to standardize shorter TTI operations to improve TCP throughput. To this end, RAN2 has already performed performance verification for short TTI.

Conduct the study and potential impacts related to RAN1 in the following range:

o Assess specification impact and study feasibility and performance of TTI lengths between 0.5ms and one OFDM symbol, taking into account impact on 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 sPDSCH at least for downlink unicast

● sPDSCH refers to 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 sPDSCH and PDSCH for downlink unicast simultaneously

o FFS: The number of supported short TTIs

o If the number of supported short 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, 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: But 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

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

Working Assumption:

-1-OFDM-symbol sTTI length will not be further studied

Agreement:

-sPDCCH (PDCCH for short TTI) needs to be introduced for short TTI.

● Each short TTI on DL may contain sPDCCH decoding candidates

Working Assumption:

-CRS-based sPDCCH is recommended to be supported

● FFS whether CRS-based sPDCCH can be transmitted in the legacy PDCCH region

-DMRS-based sPDCCH is recommended to be supported

-Design of both CRS-based sPDCCH and DMRS-based sPDCCH will be studied further.

Conclusions:

A maximum number of BDs will be defined for sPDCCH in USS

A maximum number of BDs will be defined for sPDCCH in USS

-In case 2-level DCI is adopted, any DCI for sTTI scheduling carried on PDCCH may be taken into account in the maximum total number of BDs

FFS whether the maximum number is dependent on the sTTI length

FFS whether the maximum number is dependent on the sTTI length

FFS whether the maximum number of blind decodes for (E)PDCCH is reduced in subframes in which the UE is expected to perform blind decodes for sPDCCH

FFS whether the maximum number of blind decodes for (E)PDCCH is reduced in subframes in which the UE is expected to perform blind decodes for sPDCCH

FFS whether a UE may be expected to monitor both EPDCCH and sPDCCH in the same subframe

FFS whether a UE may be expected to monitor both EPDCCH and sPDCCH in the same subframe

FFS whether the maximum number of BDs on PDCCH is changed from the legacy number

FFS whether the maximum number of BDs on PDCCH is changed from the legacy number

if DCI on PDCCH is for sTTI scheduling

Conclusion for study till RAN1#85:

Two-level DCI can be studied for sTTI scheduling, whereby:

Two-level DCI can be studied for sTTI scheduling, whereby:

-DCI for sTTI scheduling can be divided into two types:

"Slow DCI": DCI content which applies to more than 1 sTTI is carried on either legacy PDCCH, or sPDCCH transmitted not more than once per subframe

"Slow DCI": DCI content which applies to more than 1 sTTI is carried on either legacy PDCCH, or sPDCCH transmitted not more than once per subframe

FFS whether "Slow DCI" is UE-specific or common for multiple UEs

FFS whether "Slow DCI" is UE-specific or common for multiple UEs

"Fast DCI": DCI content which applies to a specific sTTI is carried on sPDCCH

"Fast DCI": DCI content which applies to a specific sTTI is carried on sPDCCH

For a sPDSCH in a given sTTI, the scheduling information is obtained from either:

For a sPDSCH in a given sTTI, the scheduling information is obtained from either:

a combination of slow DCI and fast DCI, or

a combination of slow DCI and fast DCI, or

fast DCI only, overriding the slow DCI for that sTTI

fast DCI only, overriding the slow DCI for that sTTI

-Compare with single-level DCI carried on one sPDCCH or one legacy PDCCH.

-It is not precluded to consider schemes in which the slow DCI also includes some resource allocation information for the sPDCCH.

Methods for reducing the overhead of single-level DCI can also be studied

Methods for reducing the overhead of single-level DCI can also be studied

-Single-level DCI multi-sTTI scheduling for a variable number of sTTIs may be included

Aim to reduce the number of schemes under consideration at RAN1#85.

Agreements:

Both CRS based TMs and DMRS based TMs are recommended to be supported for DL sTTI transmission

Both CRS based TMs and DMRS based TMs are recommended to be supported for DL sTTI transmission

-No change for CRS definition

FFS: Supporting more than 2 layers for sPDSCHs

FFS: Supporting more than 2 layers for sPDSCHs

-Further study is needed about DMRS design(s) for sPDSCH demodulation

For a certain TTI length, increased PRB bundling sizes may be necessary to achieve sufficient channel estimation accuracy.

For a certain TTI length, increased PRB bundling sizes may be necessary to achieve sufficient channel estimation accuracy.

FFS: the number of DMRS antenna ports that can be supported for a given short-TTI length.

FFS: the number of DMRS antenna ports that can be supported for a given short-TTI length.

For a certain TTI length, new DMRS design(s) may be needed

For a certain TTI length, new DMRS design(s) may be needed

Agreements:

A UE is expected to handle the following cases in the same carrier in a subframe

A UE is expected to handle the following cases in the same carrier in a subframe

-Receiving legacy TTI non-unicast PDSCH (except FFS for SC-PTM) and short TTI unicast PDSCH

-Receiving legacy TTI non-unicast PDSCH (except FFS for SC-PTM) and legacy TTI unicast PDSCH(s)

FFS between:

FFS between:

-Alt 1: A UE is not expected to receive legacy TTI unicast PDSCH and short TTI unicast PDSCH simultaneously on one carrier

-Alt 2: If the UE is scheduled with legacy TTI unicast PDSCH and short TTI unicast PDSCH simultaneously on one carrier, then it may skip the decoding of one of them (FFS rules for determining which one)

-Alt 3: A UE is expected to receive legacy TTI unicast PDSCH and short TTI unicast PDSCH simultaneously on one carrier

FFS UE behaviour in case of being scheduled with legacy TTI unicast PDSCH and short TTI unicast PDSCH simultaneously with legacy TTI non-unicast PDSCH (except FFS for SC-PTM) on the same carrier

FFS UE behavior in case of being scheduled with legacy TTI unicast PDSCH and short TTI unicast PDSCH simultaneously with legacy TTI non-unicast PDSCH (except FFS for SC-PTM) on the same carrier

A UE can be dynamically (with a subframe to subframe granularity) scheduled with legacy TTI unicast PDSCH and/or (depends on outcome of FFS above) short TTI PDSCH unicast

A UE can be dynamically (with a subframe to subframe granularity) scheduled with legacy TTI unicast PDSCH and/or (depends on outcome of FFS above) short TTI PDSCH unicast

Agreements:

A UE can be dynamically (with a subframe to subframe granularity) scheduled with PUSCH and/or sPUSCH

A UE can be dynamically (with a subframe to subframe granularity) scheduled with PUSCH and/or sPUSCH

-A UE is not expected to transmit PUSCH and short TTI sPUSCH simultaneously on the same REs, i.e. by superposition

-FFS whether a UE may transmit PUSCH and short TTI sPUSCH in the same subframe on one carrier by puncturing PUSCH

-FFS whether a UE may transmit PUSCH and short TTI sPUSCH in different PRBs on the same symbol(s)

-Dropping/prioritization rules (if any) are FFS

Agreements:

It is recommended to support PHICH-less asynchronous UL HARQ for PUSCH scheduled in a short TTI (i.e. for sPUSCH)

It is recommended to support PHICH-less asynchronous UL HARQ for PUSCH scheduled in a short TTI (ie for sPUSCH)

If DL data transmission is scheduled in a short TTI, the processing time for preparing the HARQ feedback by UE and the processing time for preparing a potential retransmission by eNB are assumed to be reduced

If DL data transmission is scheduled in a short TTI, the processing time for preparing the HARQ feedback by UE and the processing time for preparing a potential retransmission by eNB are assumed to be reduced

-FFS: the extent of processing time reduction

If UL data transmission is scheduled in a short TTI, the processing time for preparing UL data transmission upon UL grant reception at UE and the processing time for scheduling a potential retransmission by eNB are assumed to be reduced

If UL data transmission is scheduled in a short TTI, the processing time for preparing UL data transmission upon UL grant reception at UE and the processing time for scheduling a potential retransmission by eNB are assumed to be reduced

-FFS: the extent of processing time reduction

Study whether it is beneficial to limit the maximum TA value supported in conjunction with latency reduction

Study whether it is beneficial to limit the maximum TA value supported in conjunction with latency reduction

-Note that this would restrict the deployment scenarios for latency reduction.

FFS whether processing time reductions can also be applied to legacy TTI transmissions for UEs that support short TTI

FFS whether processing time reductions can also be applied to legacy TTI transmissions for UEs that support short TTI

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

Following 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 consists of the 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 (eNB processing and scheduling) + 1 TTI (transmission) + 1.5 TTI (UE processing) + 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

1 is a diagram for describing eNB and UE processing delays and HARQ RTT.

Assume UE is in connected/synchronized mode and wants to do UL transmission, e.g., to send TCP ACK. 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).

UL transmission latency calculation Step Description Delay One. Average delay to next SR opportunity SR periodicity/2 2. UE sends SR 1 TTI 3. eNB decodes SR and generates scheduling grant 3 TTI 4. Transmission of scheduling grant (assumed always error free) 1 TTI 5. UE processing delay (decoding Scheduling grant + L1 encoding of data) 3 TTI 6. UE sends UL transmission (1 + p*8) TTI where p is initial BLER. 7. eNB receives and decodes the UL data 1.5 TTI

In the table 1 above, steps 1-4 and half delay of step 5 is assumed to be due to SR, and rest is assumed for UL data transmission in values shown in Table 4

Resource mapping of short TTI

2 is a diagram illustrating a resource mapping per PRB in one subframe.

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 (Llegacy, e.g. 5%-50%) of the PHY layer in short TTI duration are assumed.

TBS Calculation of short TTI

According to the resource mapping and the TBS calculation formula given above, the loss rate of PHY layer for legacy PDSCH is calculated as follows:

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

TBS calculation for different TTI duration TTI Duration TBS of short TTI PDSCH (TBS _short ) 7 OFDM symbol

First time slot:

Second time slot:

2 OFDM symbol

1 OFDM symbol

As described above, research on a physical layer for a short TTI is ongoing, and specific procedures for setting sPUCCH, transmitting and receiving sPUSCH and legacy SRS are absent.

In the present invention, a terminal operation and a base station operation method for transmitting sPUCCH, short TTI based PUSCH (sPUSCH) and SRS in a short TTI-based frame structure are presented.

3 shows a signal transmission and reception method between a terminal and a base station in a short TTI-based frame structure.

In a short TTI-based frame structure, sTTI is composed of 2 or 3 symbols. The UE receives the sTTI-based sPDSCH through the downlink data channel from the base station.

When the UE receives the sPDSCH, it transmits the Ack/Nack for the received sPDSCH through sTTI-based sPUCCH, and transmits uplink data and sounding reference signals through sPUDSH.

Here, the UE configures sPUCCH for transmitting Ack/Nack through sTTI composed of 2 or 3 symbols.

In order to transmit Ack/Nack in the existing PUCCH, resource allocation is applied by spreading (OCC) + cyclic shift (CS) based on formats 1a and 1b. However, since sPUCCH has fewer symbols, we propose a CS-based Ack/Nack multiplexing resource allocation scheme of Zadoff-Chu (ZC) sequences excluding the existing OCC. That is, unlike the existing structure, sPUCCH for Ack/Nack transmission is set without using OCC spreading.

For example, unlike the existing Ack/Nack method of PUCCH, the sPUCCH can be configured such that the RS does not include RS in the sPUCCH structure and all symbols in the sPUCCH are data symbols including the Ack/Nack message.

Therefore, in order to detect the sPUCCH at the eNB, unlike the conventional method of decoding the Ack/Nack message after channel estimation through RS, only the on/off signaling needs to be detected.

At this time, since the on/off signaling cannot express Ack/Nack simultaneously in one symbol because there is no process of channel estimation, the UE uses two or more multi-CS resources to express the Ack/Nack message. In other words, the UE needs two separate CS values to represent the Ack or Nack, and allocates two CS values for each UE to construct an Ack/Nack message.

In sPUCCH, it is basically possible to assume that there will be fewer terminals than the existing PUCCH, and since not all terminals require latency reduction based services, two individual CS values can be allocated to one terminal to configure sPUCCH.

Meanwhile, when a Short TTI-based sPUSCH is transmitted, the UE may simultaneously generate a corresponding SRS (Sounding Reference Signal) and a simultaneous transmission section. At this time, the following operations are considered as alternatives in the downlink from the existing low-latency related operations.

-Alt 1: A UE is not expected to receive legacy TTI unicast PDSCH and short TTI unicast PDSCH simultaneously on one carrier

-Alt 2: If the UE is scheduled with legacy TTI unicast PDSCH and short TTI unicast PDSCH simultaneously on one carrier, then it may skip the decoding of one of them (FFS rules for determining which one)

-Alt 3: A UE is expected to receive legacy TTI unicast PDSCH and short TTI unicast PDSCH simultaneously on one carrier

Here, the operation of the UE and the scheduling method of the base station for simultaneous transmission of SRS and sPUSCH, which are not currently covered, are described.

FIG. 4 shows a conceptual diagram of transmission of sPUSCH and SRS, and FIG. 5 shows a conceptual diagram of SRS and legacy PUSCH allocation.

4 is a conceptual diagram illustrating transmission of the aforementioned sPUSCH and SRS transmissions.

That is, the existing SRS can be allocated to the last symbol of the uplink subframe. Conventional PUSCH and SRS have applied the following method to solve this problem.

Basically, in the subframe in which SRS transmission is configured as shown in FIG. 5, when the legacy PUSCH is allocated, the PUSCH allocated to the region where the SRS overlaps should consider overlapping with the SRS. In general, since SRS is a signal to be further protected, it has priority of transmission, so PUSCH adjusts information size through multiplexing. That is, in the PUSCH where the symbols overlap with the SRS, data transmission is performed only in an area excluding resources of the corresponding symbol period.

However, it is difficult to apply such legacy PUSCH and SRS overlapping solution in sPUSCH.

For example, if sTTI is defined as two symbol intervals, except for one symbol interval overlapping with SRS, only the DMRS transmission symbol interval remains, and data transmission through sPUSCH is impossible in the corresponding sTTI.

As another example, when defining sTTI with 3 OFDM symbol periods, only 2 symbols except for the DMRS 1 symbol can transmit sPUSCH, and when the SRS symbol period excludes 1 symbol period, as a result, sPUSCH in 1 symbol period. Can send.

Therefore, in some cases, the number of available data REs is insufficient, and thus data transmission is impossible or only information bits of an extremely small size are transmitted. Therefore, the range is limited in taking advantage of latency reduction. Therefore, the present invention proposes the following method to solve the problem that may occur in the overlapping section of the sPUSCH and SRS.

Option 1. Last in the subframe to sTTI Defined sPUSCH SRS When overlapping with a resource, sPUSCH transmission is unconditionally dropped. Or, skip sPUSCH transmission.

6 shows a conceptual diagram of SRS protection through sPUSCH drop.

When the SRS transmission interval and the resource of the sPUSCH overlap, the sPUSCH is omitted from the corresponding sTTI. In this case, it is assumed that the configuration for SRS transmission is predefined through RRC and SIB2, and sTTI is configured in a semi-static method. At this time, the terminal does not perform the corresponding data transmission even if the sPUSCH transmission through the corresponding sTTI is allocated. At this time, in sTTI, sPUSCH transmission may define the operation of the terminal through the following method.

① Transmission is performed again in the same sTTI of the next subframe in which SRS transmission is not performed.

■ Example: Retransmit from the last sTTI#N (assuming SRS transmission from subframe#0)

Subframe#0(sTTI#0, sTTI#1, ..., sTTI#N) → subframe#1(sTTI#0, sTTI#1,..., sTTI#N)

② Transmission is performed again in the first sTTI of the next subframe in which SRS transmission is not performed.

■ Example: Retransmit from the last sTTI#N (assuming SRS transmission from subframe#0)

Subframe#0(sTTI#0, sTTI#1, ..., sTTI#N) → subframe#1(sTTI#0, sTTI#1,..., sTTI#N)

③ The sPUSCH data is deleted from the buffer and awaits reassignment of sPUSCH.

Option 2. Last in subframe to sTTI Defined sPUSCH SRS When overlapped with a resource, sPUSCH transmission based on shortened data is performed.

When the SRS transmission interval and the resource of the sPUSCH overlap, the same shortened sPUSCH in the corresponding sTTI performs transmission. This method is applied in the same way as when the existing SRS and legacy PUSCH overlap. In addition, the UE also excludes the SRS overlapping region when calculating the number of available REs. However, if there are too few available REs remaining except for the SRS symbol period in the sTTI region, and thus cannot be used, sPUSCH transmission through the corresponding sTTI is omitted. Therefore, sPUSCH transmission is determined by considering the criterion below.

① No. of available REs> N _threshold

■ sPUSCH transmission is performed except for the SRS symbol period.

■ At this time, information size is recalculated considering available REs.

② No. of available REs ≤≤ N _threshold

■ sPUSCH transmission is not performed.

Option 3. Last in subframe to sTTI Defined sPUSCH SRS SPUSCH transmission is performed even if it overlaps with a resource.

When the SRS transmission interval and the resource of the sPUSCH overlap, the sPUSCH performs transmission regardless of the SRS configuration in the corresponding sTTI. At this time, since it may cause interference in the SRS symbol region, sPUSCH transmission is performed according to the following guide.

① When the sPUSCH and SRS section of the same UE overlap

■ The UE omits its own SRS transmission and transmits by mapping sPUSCH to symbol intervals in all sTTIs.

■ At this time, even if the SRS period is a symbol period, the SRS resource in the frequency domain and the sPUSCH period are known to overlap, so SRS detection of the corresponding region is not performed and sPUSCH detection is performed.

② When sPUSCH and SRS sections of different UEs overlap

■ Since another terminal can perform SRS transmission in the SRS configuration area, sPUSCH transmission is not performed.

■ If transmission must be performed due to the importance of information on the corresponding sPUSCH, transmission is performed at low power to minimize interference in the SRS section.

Option 4. Last in subframe to sTTI Defined sPUSCH SRS When overlapping with a resource, data transmission is performed by bundling an adjacent sTTI.

7 shows a conceptual diagram of sTTI bundling.

In this proposal, if the number of available REs of the corresponding sTTI is less than a certain number because the sTTI overlaps with the SRS symbol period, it may not be used for data transmission. Therefore, in this case, basically, sPUSCH transmission is performed by bundling with an adjacent sTTI.

At this time, since the base station knows in advance whether to overlap with the SRS symbol, the terminal performs sTTI bundling according to a predetermined pattern in performing the corresponding sTTI transmission, and calculates available RE again to perform data transmission.

For example, FIG. 7 shows an example of transmitting sPUSCH#3 by bundling sTTI#3 and #4. In this case, if the same terminal has been continuously allocated sTTI and DMRSs are included in each of the sTTIs, the following operation may be additionally defined.

① The terminal transmits DMRS only in the preceding sTTI of the bundling target and performs data transmission through sPUSCH on all symbols except the SRS transmission symbol.

■ At this time, the base station knows in advance the sTTI bundling-based transmission of the terminal and performs sPUSCH detection using only the DMRS of the preceding sTTI.

② The terminal transmits DMRS in all sTTIs to be bundled and performs data transmission through sPUSCH on all symbols except the SRS transmission symbol.

■ At this time, the base station knows in advance the bundled sTTI bundling-based transmission of the terminal and performs sPUSCH detection using all of the DMRS located in each sTTI.

Method 5. sTTI configuration SRS Transmission takes place subframe Last Symbol STTIs excluded are defined.

In this proposal, when sTTI is defined in a semi-static method, if SRS configuration is configured in a corresponding subframe, sTTI is defined in the corresponding subframe without excluding the SRS symbol period. In this case, since the SRS overlapping issue is removed during sTTI configuration, the SRS overlapping problem can be solved.

In the present invention, a specific method for solving the overlapping problem between the sTTI-based sPUSCH and SRS symbol intervals has been described, and the principle can be applied to similar signals and channels as it is.

8 shows the configuration of a base station 800 according to the present embodiments.

Referring to FIG. 8, the base station 800 according to the present exemplary embodiment includes a control unit 810, a transmitter 820, and a receiver 830.

The control unit 810 controls the overall operation of the base station 800 by performing sPUCCH setup and transmission, and sPUSCH and SRS transmission according to the present invention described above.

The transmitting unit 820 and the receiving unit 830 are used to transmit and receive signals, messages, and data necessary to perform the present invention described above.

9 shows the configuration of the user terminal 900 according to the present embodiments.

Referring to FIG. 9, the user terminal 900 according to the present exemplary embodiment includes a receiver 910, a controller 920, and a transmitter 930.

The receiving unit 910 receives downlink control information, data, and messages from a base station through a corresponding channel.

In addition, the control unit 920 controls the overall operation of the user terminal 900 according to the above-described present invention by performing sPUSCH setup and transmission, and sPUSCH and SRS transmission.

The transmitter 930 transmits uplink control information, data, and messages to the base station through a corresponding channel.

The standard contents or standard documents mentioned in the above-described embodiments are omitted to simplify the description of the specification and constitute a part of the specification. Therefore, it is to be construed that adding the contents of the above standard contents and a part of the standard documents to the present specification or in the claims falls within 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 on Latency reduction techniques for LTE", Ericsson (Rapporteur)

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

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the art to which the present invention pertains may make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, 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 interpreted by the following claims, and all technical spirits within the equivalent range should be interpreted as being included in the scope of the present invention.

Claims (20)

In a method for a terminal to transmit an uplink channel in a frame structure with a short transmission time interval,
Receiving downlink data from a base station through a downlink data channel having a short transmission time interval;
Transmitting the Ack/Nack for the downlink data to the base station through an uplink control channel with a short transmission time interval; And
And transmitting the uplink data and the sounding reference signal to the base station through a short transmission time interval uplink data channel,
Transmitting at least one of the uplink data and the sounding reference signal through at least one of the uplink data channels of the short transmission time interval included in one subframe,
When the uplink data and the sounding reference signal overlap the same symbol of the uplink data channel of the short transmission time interval, the method of transmitting the uplink data by bundling with the uplink data channel of the adjacent short transmission time interval. delete delete delete According to claim 1,
A method of configuring an uplink data channel of the short transmission time interval using symbols except for a symbol on which the sounding reference signal is transmitted in one subframe. According to claim 1,
A method of allocating different cyclic shift values to the Ack/Nack and configuring the uplink control channel of the short transmission time interval including the Ack/Nack based on the cyclic shift value. The method of claim 6,
A method in which all symbols included in the uplink control channel of the short transmission time interval are allocated for the Ack/Nack. In a method for a base station to receive an uplink channel in a frame structure of a short transmission time interval,
Transmitting downlink data to a terminal through a downlink data channel having a short transmission time interval;
Receiving the Ack/Nack for the downlink data through an uplink control channel having a short transmission time interval; And
And receiving uplink data and a sounding reference signal through the uplink data channel having a short transmission time interval from the terminal,
Receiving at least one of the uplink data and the sounding reference signal through at least one of the uplink data channels of the short transmission time interval included in one subframe,
When the uplink data and the sounding reference signal overlap the same symbol of the uplink data channel of the short transmission time interval, the uplink data transmitted by bundling with the uplink data channel of the adjacent short transmission time interval is received. Way. delete delete delete The method of claim 8,
A method of configuring an uplink data channel of the short transmission time interval using symbols except for a symbol in which the sounding reference signal is transmitted in one subframe. The method of claim 8,
A method of allocating different cyclic shift values to the Ack/Nack and receiving the Ack/Nack through the uplink control channel of the short transmission time interval configured based on the cyclic shift values. The method of claim 13,
A method in which all symbols included in the uplink control channel of the short transmission time interval are allocated for the Ack/Nack. In a method for a terminal to transmit an uplink channel in a frame structure with a short transmission time interval,
Receiving downlink data from a base station through a downlink data channel having a short transmission time interval;
Configuring an uplink control channel of a short transmission time interval including Ack/Nack by assigning individual cyclic shift values to Ack/Nack, respectively; And
And transmitting the Ack/Nack for the downlink data to the base station through the uplink control channel of the short transmission time interval,
The method for transmitting the Ack/Nack through all symbols included in the uplink control channel in the short transmission time interval, the reference signal does not include the uplink control channel in the short transmission time interval. The method of claim 15,
The cyclic shift values respectively assigned to the Ack/Nack have different values from each other. delete In a method for a base station to receive an uplink channel in a frame structure of a short transmission time interval,
Transmitting downlink data to a terminal through a downlink data channel having a short transmission time interval; And
And receiving the Ack/Nack for the downlink data through the uplink control channel having a short transmission time interval from the terminal,
The uplink control channel of the short transmission time interval is configured in such a way that individual cyclic shift values are allocated to the Ack/Nack, respectively.
The method for receiving the Ack/Nack through all symbols included in the uplink control channel in the short transmission time interval, the reference channel does not include a reference signal. The method of claim 18,
The cyclic shift values respectively assigned to the Ack/Nack have different values from each other. delete

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