JP2020114026A - Terminal, communication method and integrated circuit - Google Patents

Abstract

To appropriately set the timing of data allocation, data transmission/reception, and feedback when sTTI length differs between DL and UL.SOLUTION: In a base station 100, a transmission part 106 transmits a downlink signal by using a down link first sTTI (short TTI, DL sTTI) a TTI shorter in length than TTI (Transmission Time Interval) and a receiving part 107 receives an incoming signal by using an uplink second sTTI (UL sTTI) with the TTI length shorter than TTI. The receiving part 107 is configured so as to, when the length of first sTTI is shorter than second sTTI, receive the incoming signal at second sTTI after a predetermined interval set on the basis of the length of first sTTI from the transmission timing of the downlink signal.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to a base station, a terminal and a communication method.

In recent years, it has been considered to realize an application that requires a reduced delay time (delay critical). Examples of applications that require a reduced delay time include autonomous driving of vehicles, ultra-realistic applications in smart glasses, and communication between devices.

In 3GPP, in order to realize these applications, latency reduction that reduces packet delay is being studied (see Non-Patent Document 1). Latency reduction is considered to reduce the TTI (Transmission Time Interval) length, which is the time unit for transmitting and receiving data, to a length between 0.5 msec and 1 OFDM symbol. The conventional TTI length is 1 msec, which is equal to a unit called a subframe. One subframe consists of 2 slots (1 slot is 0.5 msec). One slot is composed of 7 OFDM (Orthogonal Frequency Division Multiplexing) symbols in the case of normal CP (Cyclic Prefix), and is composed of 6 OFDM symbols in the case of extended CP.

FIG. 1 shows an example of a shortened TTI in the case of normal CP. When the TTI length is 0.5 msec (=1 slot), 2 TTIs are arranged per 1 msec. Moreover, when 1 slot is divided into a TTI of 4 OFDM symbols and a TTI of 3 OFDM symbols, 4 TTIs are arranged per 1 msec. Also, when the TTI length is 1 OFDM symbol, 14 TTIs are arranged per 1 msec.

By shortening the TTI length, the delay of CQI reporting can be shortened and the frequency of CQI reporting can be increased, so that there is an advantage that the difference between CQI reporting and actual line quality is reduced.

RP-150465, "New SI proposal: Study on Latency reduction techniques for LTE," Ericsson, Huawei, March 2015 3GPP TR 36.211 V13.0.0, “Physical channels and modulation (Release 13),” December 2015

When shortening the TTI length, it can be considered that the length of the shortened TTI (sTTI: short TTI) is different between DL (Downlink) and UL (Uplink). However, in the conventional LTE/LTE-advanced, DL and UL have the same TTI length, and the timings of data allocation, data transmission, and feedback are commonly defined based on the same TTI length. Therefore, it is necessary to newly define the timing of data allocation, data transmission/reception, and feedback when DL and UL have different sTTI lengths.

One aspect of the present disclosure is to provide a base station, a terminal, and a communication method capable of appropriately setting timings of data allocation, data transmission/reception, and feedback when sTTI lengths are different between DL and UL.

A base station according to an aspect of the present disclosure includes a transmission unit that transmits a downlink signal using a first sTTI (short TTI) of a downlink whose TTI length is shorter than TTI (Transmission Time Interval), and a TTI that is higher than the TTI. A receiver for receiving an uplink signal using the second sTTI of the uplink with a shortened length, and when the length of the first sTTI is shorter than the second sTTI, the receiver transmits the downlink signal. From the timing, the uplink signal is received at the second sTTI after a predetermined interval set based on the length of the first sTTI.

A terminal according to an aspect of the present disclosure includes a receiving unit that receives a downlink signal using a first sTTI (short TTI) of a downlink whose TTI length is shorter than TTI (Transmission Time Interval), and a TTI length that is longer than the TTI. And a transmitter that transmits an uplink signal using the second sTTI of the uplink that is shortened, and if the length of the first sTTI is shorter than the second sTTI, the transmitter determines the reception timing of the downlink signal. From the above, the uplink signal is transmitted at the second sTTI after the predetermined interval set with the length of the first sTTI as a reference.

A communication method according to an aspect of the present disclosure transmits a downlink signal using a first sTTI (short TTI) of a downlink whose TTI length is shorter than TTI (Transmission Time Interval), and shortens the TTI length from the TTI. When an upstream signal is received by using the second sTTI of the uplink, and the length of the first sTTI is shorter than the second sTTI, the upstream signal has the length of the first sTTI from the transmission timing of the downstream signal. It is received at the second sTTI after the predetermined interval set as the reference.

A communication method according to an aspect of the present disclosure receives a downlink signal by using a first sTTI (short TTI) of a downlink whose TTI length is shorter than TTI (Transmission Time Interval), and shortens the TTI length from the TTI. When the uplink signal is transmitted using the second sTTI of the uplink, and the length of the first sTTI is shorter than the second sTTI, the uplink signal has the length of the first sTTI from the reception timing of the downlink signal. It is transmitted at the second sTTI after the predetermined interval set as the reference.

Note that these comprehensive or specific aspects may be realized by a system, a device, a method, an integrated circuit, a computer program, or a recording medium. The system, the device, the method, the integrated circuit, the computer program, and the recording medium. May be realized in any combination.

According to an aspect of the present disclosure, it is possible to appropriately set timings of data allocation, data transmission/reception, and feedback when sTTI lengths are different between DL and UL.

Further advantages and effects of one aspect of the present disclosure will be apparent from the specification and the drawings. Such advantages and/or effects are provided by the features described in several embodiments and in the specification and drawings, respectively, but not necessarily all to obtain one or more of the same features. There is no.

Figure showing an example of TTI length FIG. 3 is a block diagram showing the main configuration of the base station according to the first embodiment. FIG. 3 is a block diagram showing the main configuration of the terminal according to the first embodiment. Block diagram showing the configuration of the base station according to the first embodiment Block diagram showing the configuration of the terminal according to the first embodiment The figure which shows an example of the transmission/reception timing at the time of UL data allocation which concerns on Embodiment 1 (operation example 1-1) The figure which shows an example of the transmission/reception timing at the time of UL data allocation which concerns on Embodiment 1 (Operation example 1-2) The figure which shows the other example of the transmission/reception timing at the time of UL data allocation which concerns on Embodiment 1 (Operation example 1-2) The figure which shows an example of the transmission/reception timing at the time of UL data allocation which concerns on Embodiment 1 (Operation example 1-3) The figure which shows the other example of the transmission/reception timing at the time of UL data allocation which concerns on Embodiment 1 (Operation example 1-3) FIG. 3 is a diagram showing an example of transmission/reception timing when DL data is allocated according to the first embodiment (operation example 2-1) FIG. 6 is a diagram showing an example of transmission/reception timing when DL data is allocated according to the first embodiment (operation example 2-2) FIG. 8 is a diagram showing another example of transmission/reception timing when DL data is allocated according to Embodiment 1 (Operation Example 2-2) FIG. 8 is a diagram showing another example of transmission/reception timing when DL data is allocated according to Embodiment 1 (Operation Example 2-2) FIG. 6 is a diagram showing another example of transmission/reception timing when DL data is allocated according to the first embodiment (operation example 2-3) The figure which shows an example of the transmission/reception timing at the time of UL data allocation which concerns on Embodiment 2. FIG. 11 is a diagram showing another example of transmission/reception timing when DL data is allocated according to the second embodiment. The figure which shows an example of the transmission/reception timing at the time of UL data allocation which concerns on Embodiment 3. The figure which shows the other example of the transmission/reception timing at the time of UL data allocation which concerns on Embodiment 3. The figure which shows an example of the transmission/reception timing at the time of UL data allocation which concerns on Embodiment 4.

[Background to One Aspect of the Present Disclosure]
3GPP uses OFDM in DL and single carrier transmission in UL.

In UL, in order to maintain single carrier transmission, a reference signal (DMRS: demodulation reference signal) and a data signal (PUSCH: Physical Uplink Shared Channel) cannot be arranged in the same symbol, and the overhead of the reference signal increases. There is. Further, in UL, since a terminal (UE: User Equipment) transmits a signal, the transmission power per time unit is lower than the DL at which the base station (eNB) transmits the signal. Therefore, in UL, the UE needs to spread resources on the time axis to transmit a signal in order to secure desired reception power.

On the other hand, since DL uses OFDM, it is easy to frequency-multiplex a reference signal and a data signal (PDSCH: Physical Downlink Shared Channel), and sTTI (shorter TTI length) is easier to introduce than UL. In addition, DL traffic volume is considered to be larger than UL traffic volume, and Latency reduction is required more.

From the above, when shortening the TTI length, DL may set sTTI shorter than UL.

Therefore, in one aspect of the present disclosure, when the sTTI lengths differ between DL and UL, in particular, the length of DL sTTI (hereinafter referred to as “DL sTTI”) is UL sTTI (hereinafter referred to as “UL sTTI”). The purpose is to appropriately define the data allocation, data transmission/reception, and feedback transmission/reception timing when the length is shorter than the length of (indicated).

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[Outline of communication system]
The communication system according to each embodiment of the present disclosure includes a base station 100 and a terminal 200.

FIG. 2 is a block diagram showing a main configuration of base station 100 according to the embodiment of the present disclosure. In the base station 100 shown in FIG. 2, the transmission unit 106 transmits a downlink signal using the first sTTI (short TTI. DL sTTI) of the downlink whose TTI length is shorter than TTI (Transmission Time Interval), and the reception unit. 107 receives an uplink signal using the second sTTI (UL sTTI) on the uplink, which has a shorter TTI length than TTI. When the length of the first sTTI is shorter than the second sTTI, the receiving unit 107 receives the uplink signal at the second sTTI after a predetermined interval set with reference to the length of the first sTTI from the transmission timing of the downlink signal.

Further, FIG. 3 is a block diagram showing a main configuration of terminal 200 according to each embodiment of the present disclosure. In terminal 200 shown in FIG. 3, receiving section 201 receives a downlink signal using first sTTI (short TTI. DL sTTI) of the downlink whose TTI length is shorter than TTI (Transmission Time Interval), and transmitting section 212 Transmits an uplink signal using the second sTTI (UL sTTI) on the uplink, which has a shorter TTI length than TTI. When the length of the first sTTI is shorter than the second sTTI, the transmission unit 212 transmits the uplink signal at the second sTTI after a predetermined interval set with reference to the length of the first sTTI from the reception timing of the downlink signal.

Further, in the following, sTTI (DL sTTI, UL sTTI) is assigned, UL data signal is represented as "sPUSCH", DL data signal is represented as "sPDSCH", UL grant or DL assignment downlink control signal ( PDCCH: Physical Downlink Control Channel is represented as "sPDCCH".

(Embodiment 1)
[Base station configuration]
FIG. 4 is a block diagram showing the configuration of base station 100 according to the present embodiment. 4, the base station 100 includes an sTTI determining unit 101, an sPDCCH generating unit 102, an error correction coding unit 103, a modulating unit 104, a signal allocating unit 105, a transmitting unit 106, and a receiving unit 107. The signal separation unit 108, the ACK/NACK reception unit 109, the demodulation unit 110, the error correction decoding unit 111, and the ACK/NACK generation unit 112 are included.

The sTTI determining unit 101 determines the sTTI length of DL and UL. The sTTI determining unit 101 outputs sTTI information indicating the determined sTTI length to the sPDCCH generating unit 102, the signal allocating unit 105, and the signal separating unit 108. In addition, the sTTI determining unit 101 outputs the sTTI information to the error correction coding unit 103 as upper layer signaling.

The sPDCCH generation unit 102 determines the data size that can be transmitted and received by sTTI based on the sTTI information input from the sTTI determination unit 101. The sPDCCH generation unit 102 generates an sPDCCH including DL or UL resource allocation information (for example, DL assignment or UL grant). The sPDCCH generation section 102 outputs the generated sPDCCH to the signal allocation section 105 for transmission to the terminal 200. Also, sPDCCH generating section 102 outputs DL resource allocation information to signal allocation section 105 and outputs UL resource allocation information to signal demultiplexing section 108.

In addition, the sPDCCH generation unit 102 receives the DL data based on the content (ACK or NACK) of the ACK/NACK signal (that is, the ACK/NACK signal for the DL data signal (sPDSCH)) input from the ACK/NACK reception unit 109. It is determined whether or not the signal needs to be retransmitted, and sPDCCH is generated according to the determination result.

Details of data assignment (DL assignment, UL grant), data transmission/reception (PDSCH, PUSCH), and feedback (ACK/NACK signal) transmission/reception timing in the base station 100 will be described later.

Error correction coding section 103 performs error correction coding on the transmission data signal (DL data signal) and higher layer signaling input from sTTI determining section 101, and outputs the coded signal to modulating section 104.

Modulation section 104 performs modulation processing on the signal received from error correction coding section 103, and outputs the modulated signal to signal allocation section 105.

The signal allocation unit 105 receives the signal received from the modulation unit 104, the control signal (sPDCCH) received from the sPDCCH generation unit 102, or the ACK/NACK generation unit 112 based on the sTTI information input from the sTTI determination unit 101. The ACK/NACK signal (that is, the ACK/NACK signal for the UL data signal (sPDSCH)) is allocated to a predetermined downlink resource. By thus allocating the control signal (sPDCCH) or the data signal (sPDSCH) to a predetermined resource, a transmission signal is formed. The formed transmission signal is output to the transmission unit 106.

The transmission unit 106 performs radio transmission processing such as up-conversion on the transmission signal input from the signal allocation unit 105, and transmits the transmission signal to the terminal 200 via the antenna.

Receiving section 107 receives the signal transmitted from terminal 200 via the antenna, performs radio receiving processing such as down conversion on the received signal, and outputs the signal to signal separating section 108.

The signal separation unit 108, based on the UL resource allocation information input from the sPDCCH generation unit 102 and the sTTI information input from the sTTI determination unit 101, the reception frequency and time of the sPUSCH (UL data signal) and the ACK/NACK signal. Identify the timing. Then, signal separating section 108 separates the UL data signal from the received signal and outputs it to demodulating section 110, separates the ACK/NACK signal from the received signal and outputs it to ACK/NACK receiving section 109.

The ACK/NACK receiving unit 109 outputs the content (ACK or NACK) of the ACK/NACK signal for the DL data signal, which is input from the signal separating unit 108, to the sPDCCH generating unit 102.

Demodulation section 110 performs demodulation processing on the signal input from signal separation section 108, and outputs the obtained signal to error correction decoding section 111.

The error correction decoding unit 111 decodes the signal input from the demodulation unit 110 and obtains a reception data signal (UL data signal) from the terminal 200. The error correction decoding unit 111 outputs the UL data signal to the ACK/NACK generation unit 112.

The ACK/NACK generation unit 112 determines whether or not there is an error in the UL data signal input from the error correction decoding unit 111 using CRC (Cyclic Redundancy Check), and the determination result is ACK/NACK. The signal is output to the signal allocation unit 105.

[Terminal configuration]
FIG. 5 is a block diagram showing the configuration of terminal 200 according to the present embodiment. 5, terminal 200 includes receiving section 201, signal separating section 202, demodulating section 203, error correction decoding section 204, sTTI setting section 205, error determining section 206, ACK/NACK generating section 207. , SPDCCH reception section 208, error correction coding section 209, modulation section 210, signal allocation section 211, and transmission section 212.

The receiving unit 201 receives a received signal via an antenna, performs reception processing such as down conversion on the received signal, and then outputs the received signal to the signal separation unit 202.

The signal demultiplexing unit 202 demultiplexes the signal (sPDCCH signal) allocated to the resource to which the sPDCCH may be assigned, based on the DL sTTI length input from the sTTI setting unit 205, and outputs it to the sPDCCH receiving unit 208. To do. Further, the signal demultiplexing unit 202 demultiplexes the DL data signal (sPDSCH) from the received signal based on the DL resource allocation information input from the sPDCCH receiving unit 208, and outputs it to the demodulation unit 203.

Demodulation section 203 demodulates the signal received from signal separation section 202 and outputs the demodulated signal to error correction decoding section 204.

The error correction decoding unit 204 decodes the demodulated signal received from the demodulation unit 203 and outputs the obtained received data signal. Further, the error correction decoding unit 204 outputs the received data signal to the error determination unit 206. Also, the error correction decoding unit 204 decodes the demodulated signal received from the demodulation unit 203, and outputs the obtained upper layer signaling (including sTTI information) to the sTTI setting unit 205.

The sTTI setting unit 205 sets the sTTI length of DL and UL based on the sTTI information input from the error correction decoding unit 204, outputs information indicating the set DL sTTI length to the signal separation unit 202, and sets the information. Information indicating the UL sTTI length is output to the signal allocation unit 211.

The error determination unit 206 detects an error in the CRC of the received data signal and outputs the detection result to the ACK/NACK generation unit 207.

The ACK/NACK generation unit 207 generates an ACK if there is no error based on the detection result of the received data signal input from the error determination unit 206, generates a NACK if there is an error, and generates the generated ACK/ The NACK signal is output to signal allocation section 211.

The sPDCCH reception unit 208 extracts resource allocation information (DL resource allocation information, UL resource allocation information) from the sPDCCH received from the signal separation unit 202, outputs DL resource allocation information to the signal separation unit 202, and outputs UL resource allocation information. Is output to the signal allocation unit 211.

Error correction coding section 209 performs error correction coding on the transmission data signal (UL data signal) and outputs the coded data signal to modulation section 210.

Modulation section 210 modulates the data signal received from error correction coding section 209 and outputs the modulated data signal to signal allocation section 211.

The signal allocation unit 211 allocates the data signal input from the modulation unit 210 to a resource based on the information indicating the UL sTTI length received from the sTTI setting unit 205 and the UL resource allocation information received from the sPDCCH reception unit 208, and transmits the resource. Output to the unit 212. Further, the signal allocating unit 211 allocates the ACK/NACK signal input from the ACK/NACK generating unit 207 to the ACK/NACK resource, or multiplexes the UL data signal and outputs the UL data signal to the transmitting unit 212.

Details of the data assignment (DL assignment, UL grant) reception, data transmission/reception (PDSCH, PUSCH), and feedback (ACK/NACK signal) transmission/reception timing in terminal 200 will be described later.

The transmission unit 212 performs transmission processing such as up-conversion on the signal input from the signal allocation unit 211, and transmits the signal via the antenna.

In addition, the terminal 200 receives the UL data signal based on the content (ACK or NACK) of the ACK/NACK signal (that is, the ACK/NACK signal for the UL data signal (sPUSCH)) separated from the received signal in the signal separation unit 202. It is determined whether or not the sPUSCH needs to be retransmitted, and sPUSCH is retransmitted according to the determination result (not shown).

[Operations of Base Station 100 and Terminal 200]
The operations of base station 100 and terminal 200 having the above configurations will be explained in detail.

In the present embodiment, the DL sTTI length and the UL sTTI length are different, and when the DL sTTI length is shorter than the UL sTTI length, base station 100 and terminal 200 allocate data based on the DL sTTI length (in the sPDCCH). UL grant, DL assignment), data transmission/reception (sPUSCH, sPDSCH), and feedback (ACK/NACK signal) transmission/reception timing are determined.

Specifically, with respect to DL data, the terminal 200 (transmission unit 212) sets the sTTI that receives the sPDCCH including the DL assignment and the sPDSCH assigned by the DL assignmetn to be the same DL sTTI. Also, the terminal 200 receives an ACK/ACK for the sPDSCH with a UL sTTI after a predetermined interval that is set based on the length of the DL sTTI from the timing of the DL sTTI that has received the sPDSCH (that is, the DL sTTI that has received the DL assignment). Send a NACK signal. That is, the base station 100 (reception unit 107) determines the UL after the predetermined interval set based on the length of the DL sTTI from the timing of the DL sTTI that transmitted the sPDSCH (DL sTTI that transmitted the DL assignment of the sPDSCH). The ACK/NACK signal for the sPDSCH is received by sTTI.

Regarding UL data, terminal 200 (transmission section 212) transmits sPUSCH with UL sTTI after a predetermined interval set based on the length of DL sTTI from the reception timing of sPDCCH including UL grant. That is, the base station 100 (reception unit 107) receives the sPUSCH with UL sTTI after a predetermined interval set based on the length of DL sTTI from the transmission timing of sPDCCH including UL grant.

Also, the base station 100 (transmitting unit 106) transmits an ACK/NACK signal for the sPUSCH with a DL sTTI after a predetermined interval set based on the length of the DL sTTI from the timing of the UL sTTI that received the sPUSCH. .. That is, the terminal 200 (reception unit 201) receives the ACK/NACK signal for the sPUSCH at DL sTTI after a predetermined interval from the UL sTTI timing at which the sPUSCH was transmitted.

Also, if the UL timing determined based on the DL sTTI length does not match the UL sTTI boundary, the base station 100 and the terminal 200 match the UL signal (sPUSCH or ACK/NACK signal) transmission/reception with the UL sTTI boundary. Delay until the timing.

For example, the base station 100 and the terminal 200 define the timing of data allocation, data transmission/reception, and feedback (transmission timing of the second signal with respect to the first signal) as follows.
Timing for DL data
DL assignment in sPDCCH-sPDSCH: same sTTI
sPDSCH-ACK/NACK feedback: at least after X DL sTTIs
Timing for UL data
UL grant in sPDCCH-sPUSCH: at least after X DL sTTIs
sPUSCH-ACK/NACK feedback: at least after X DL sTTIs

Note that "at least X DL sTTIs" means the second signal (above sPDSCH, ACK/NACK feedback, after the transmission and reception of the first signal (above DL assignment, sPDSCH, UL grant or sPUSCH) is completed. It indicates that there is an interval of at least (X-1)sTTI until the transmission/reception of sPUSCH or ACK/NACK feedback) is started, and the second signal is assigned to the first sTTI after the interval.

Hereinafter, operations of data allocation, data transmission/reception, and feedback in the base station 100 and the terminal 200 will be described in detail.

First, an operation example when UL data is assigned will be described. UL data allocation assumes synchronous HARQ. In the following operation example, the HARQ process ID is shown for the sake of explanation. However, the HARQ process ID is not notified to the terminal 200, and the base station 100 and the terminal 200 respectively receive the UL sTTI number and the HARQ process ID. It is associated with the ID.

<Operation example 1-1: UL data allocation (UL 7 symbols sTTIs and DL 3/4 symbols sTTIs)>
FIG. 6 is a transmission/reception timing of sPDCCH and sPUSCH in which UL grants for instructing transmission of UL data signal (sPUSCH) in operation example 1-1, and transmission/reception of sPUSCH and ACK/NACK signal for the sPUSCH are transmitted and received. An example of timing is shown.

In the operation example 1-1, as shown in FIG. 6, the UL sTTI length is set to 7 symbols, the DL sTTI length is set to 3/4 symbols, and X=4. In 3/4 symbols of sTTIs, sTTI is composed of the first 4 symbols and the latter 3 symbols in one slot (that is, two sTTIs per slot) (for example, see FIG. 1). That is, in FIG. 6, there are four DL sTTIs per subframe, and DL sTTIs #0 to #19 are assigned from subframe #0 to subframe #4. Further, in FIG. 6, there are two UL sTTIs per subframe, and UL sTTIs #0 to #9 are assigned from subframe #0 to subframe #4.

That is, in operation example 1-1, the number of DL sTTIs (4 per subframe) is twice the number of UL sTTIs (2 per subframe).

With respect to UL grant and sPUSCH, when X=4, base station 100 and terminal 200 start transmission/reception of sPUSCH at least 4 DL sTTIs after transmission/reception of UL grant (sPDCCH) on the basis of DL sTTI length. That is, there is an interval of at least 3 DL sTTI (=X-1) from the completion of transmission/reception of UL grant to the start of transmission/reception of sPUSCH. That is, the base station 100 and the terminal 200 transmit/receive sPUSCH with the first UL sTTI after the 3 DL sTTI interval from the UL grant transmission/reception timing.

For example, when the base station 100 transmits a UL grant of HARQ process ID #0 with DL sTTI#0, the timing after the 3DL sTTI interval from the timing when the transmission/reception of the UL grant is completed (DL sTTI#0) is DL sTTI. It is #4. Therefore, the terminal 200 transmits the sPUSCH of HARQ process ID #0 at UL sTTI#2, which is the same timing as DL sTTI#4.

Similarly, for sPUSCH and ACK/NACK signal, when X=4, the base station 100 and the terminal 200 reference the DL sTTI length, and at least 4 DL sTTIs after sPUSCH transmission/reception, ACK/NACK signal for the sPUSCH. Start sending and receiving. That is, there is at least an interval of 3 DL sTTI from the completion of transmission/reception of sPUSCH to the start of transmission/reception of ACK/NACK signals. That is, the base station 100 and the terminal 200 transmit/receive an ACK/NACK signal at the first DL sTTI after an interval of 3 DL sTTI from the transmission/reception timing of sPUSCH.

For example, when the terminal 200 transmits the sPUSCH of HARQ process ID#0 with UL sTTI#2, the timing after the 3DL sTTI interval from the timing (DL sTTI#5) when the transmission/reception of sPUSCH is completed is DL sTTI#9. is there. Therefore, the base station 100 transmits an ACK/NACK signal for the sPUSCH of HARQ process ID#0 with DL sTTI#9.

Thus, when X=4, base station 100 and terminal 200 allocate UL grant and sPUSCH, and sPUSCH and ACK/NACK signal at intervals of 3 DL sTTI or more, respectively.

Note that in FIG. 6, the number of symbols corresponding to the 3 DL sTTI interval differs depending on the combination of DL sTTIs forming the 3 DL sTTI interval. Specifically, in the case of DL sTTI#1,2,3, the 3 DL sTTI interval is 10 OFDM symbols, but in the case of DL sTTI#6,7,8, the 3 DL sTTI interval is 11 OFDM symbols. This is because the DL sTTI may be composed of 4 symbols or 3 symbols.

Further, in the operation example 1-1, the UL grant is arranged only in the rearmost DL sTTI at the timing (X-1) DL sTTI (3 DL sTTI in FIG. 6) or more before the timing of the boundary of the UL sTTI. And limit. In this way, as shown in FIG. 6, among a plurality of DL sTTIs, UL grants are arranged in half DL sTTIs and UL grants are not arranged in the remaining half DL sTTIs. By this means, it is possible to reduce the probability (false alert) of erroneously detecting a UL grant, as compared to the case where terminal 200 monitors UL grant in all DL sTTIs.

Further, in the operation example 1-1, the DL sTTI in which the ACK/NACK signal is transmitted/received is different from the DL sTTI in which the UL grant is transmitted/received. In this way, the resources used for UL grant and the resources used for ACK/NACK signals are different, so that there is an advantage that the congestion degree of resources in which control signals are arranged is relaxed. By this means, it is possible to avoid limiting UL data allocation due to lack of control signal resources in DL.

Next, in FIG. 6, there are three methods (options 1 to 3) for the operation when the terminal 200 receives the ACK/NACK signal of HARQ process ID#0 in DL sTTI#9.

Option 1:
After receiving the ACK/NACK signal in DL sTTI#9, terminal 200 transmits DL grant corresponding to the same HARQ process ID#0 regardless of whether the ACK/NACK signal is ACK or NACK. Attempt to detect UL grant at 10. When detecting UL grant in DL sTTI#10, terminal 200 discards the ACK/NACK signal and transmits sPUSCH according to the UL grant instruction. On the other hand, when the UL grant is not detected in DL sTTI#10, terminal 200 receives UL data signal (sPUSCH) of HARQ process ID#0 when the ACK/NACK signal received in DL sTTI#9 is ACK. If the ACK/NACK signal received in DL sTTI#9 is NACK, the retransmission signal of HARQ process ID #0 is transmitted in UL sTTI#7.

Option 2:
When the ACK/NACK signal received in DL sTTI#9 is ACK, terminal 200 attempts to detect UL grant in DL sTTI#10, where UL grant corresponding to the same HARQ process ID#0 is transmitted. When detecting the UL grant, the terminal 200 transmits the sPUSCH according to the instruction of the UL grant. On the other hand, when the UL grant is not detected, the terminal 200 does not transmit the UL data signal (sPUSCH) of HARQ process ID#0. Further, when the ACK/NACK signal received in DL sTTI#9 is NACK, terminal 200 does not detect UL grant in DL sTTI#10 in which UL grant corresponding to the same HARQ process ID#0 is transmitted. Then, the retransmission signal of HARQ process ID #0 is transmitted by UL sTTI#7.

Option 3:
The terminal 200 attempts to detect NACK with DL sTTI#9. When NACK is not detected in DL sTTI#9, terminal 200 attempts to detect UL grant in DL sTTI#10, where UL grant corresponding to the same HARQ process ID#0 is transmitted. When detecting UL grant in DL sTTI#10, terminal 200 transmits sPUSCH according to the UL grant instruction. On the other hand, when DL sTTI#10 does not detect UL grant, terminal 200 does not transmit the UL data signal (sPUSCH) of HARQ process ID#0. Further, when NACK is detected in DL sTTI#9, terminal 200 transmits HAR grant corresponding to the same HARQ process ID#0 and does not detect UL grant in DL sTTI#10, and terminal 200 receives HARQ process ID# Send a retransmission signal of 0 by UL sTTI#7.

As described above, in Option 1 and Option 2, the ACK/NACK signal is always transmitted as ACK or NACK as in the case of the conventional PHICH (Physical HARQ Indicator Channel), and the terminal 200 determines whether it is ACK or NACK. It is premised on judging. In option 3, the ACK/NACK signal is transmitted only in the case of NACK (with error), and the terminal 200 is premised on detecting whether or not the ACK/NACK signal is present.

In option 1, since terminal 200 always attempts to detect UL grant, even if it erroneously determines ACK as NACK, if UL grant is detected, it is possible to prevent retransmission signals from being transmitted at incorrect timing. it can. In addition, in option 2 and option 3, since terminal 200 does not detect UL grant when NACK is detected, power consumption of terminal 200 can be suppressed.

The minimum number of UL HARQ processes is determined from the sPUSCH transmission interval of the same UL HARQ process ID. In FIG. 6, sPUSCH of UL HARQ process ID#0 is transmitted in UL sTTI#2, and ACK/NACK for it is transmitted in DL sTTI#9. Therefore, since it is determined in DL sTTI#9 whether retransmission is necessary, the base station 100 can transmit the UL grant of the same UL HARQ ID#0 after DL sTTI#9. When base station 100 transmits UL grant with DL sTTI#9 (DL sTTI#10 in FIG. 10, details will be described later), terminal 200 transmits sPUSCH at the first UL sTTI after 3 DL sTTI intervals. It becomes a certain UL sTTI #7. Therefore, the sPUSCH of the same UL HARQ process ID#0 can be transmitted in 5 UL sTTI intervals. When the transmission interval of the same UL HARQ process is 5 UL sTTI, 5 UL HARQ processes can be transmitted during 5 UL sTTI, and thus the minimum number of UL HARQ processes can be determined to be 5.

The number of UL HARQ processes can be set to a value greater than 5. In that case, the retransmission interval becomes long and the delay time increases. Also, as the number of UL HARQ processes increases, the required buffer also increases accordingly, so it is desirable to set the number of UL HARQ processes to the minimum possible value.

Note that, in FIG. 6, the base station 100 does not transmit UL grant in DL sTTI #9, but transmits UL grant in DL sTTI #10 that is 3 DL sTTI intervals before UL sTTI #7. This is because transmitting the UL grant with DL sTTI#10 does not affect the overall delay amount. The number of UL HARQ processes may be determined in advance from the DL sTTI length and the UL sTTI length, and as described above, the minimum possible value is specified and set in the base station 100 and the terminal 200, respectively. Good.

Also, here, the focus is on HARQ process ID#0, but the same applies to the other HARQ process ID#2 to #4.

<Operation example 1-2: UL data allocation (UL 3/4 symbols sTTIs and DL 2 symbols sTTIs)>
FIG. 7 is a transmission/reception timing of sPDCCH and sPUSCH in which a UL grant that instructs transmission of a UL data signal (sPUSCH) is arranged, and transmission/reception of sPUSCH and an ACK/NACK signal for the sPUSCH in operation example 1-2. An example of timing is shown.

In the operation example 1-2, as shown in FIG. 7, the UL sTTI length is 3/4 symbols, the DL sTTI length is 2 symbols, and X=4. That is, in FIG. 7, there are seven DL sTTIs per subframe, and DL sTTIs #0 to #27 are assigned from subframe #0 to subframe #3. Further, in FIG. 7, there are four UL sTTIs per subframe, and UL sTTIs #0 to #15 are allocated from subframe #0 to subframe #3.

That is, in operation example 1-2, the number of DL sTTIs (7 per subframe) is 7/4 times the number of UL sTTIs (4 per subframe).

When X=4, the base station 100 and the terminal 200 allocate UL grant and sPUSCH, and sPUSCH and ACK/NACK signal at intervals of 3 DL sTTI or more, respectively, as in the operation example 1-1.

For example, for UL grant and sPUSCH, when the base station 100 transmits a UL grant of HARQ process ID #0 with DL sTTI#1, an interval of 3DL sTTI from the timing (DL sTTI#1) when UL grant transmission/reception is completed. The later timing is DL sTTI#5. Since the timing of DL sTTI#5 does not coincide with the UL sTTI boundary, the terminal 200 delays the transmission of sPUSCH until UL sTTI#3, which is the first UL TTI behind the timing of DL sTTI#5, and UL sTTI#5. Send sPUSCH with HARQ process ID #0 in #3.

Similarly, for the sPUSCH and the ACK/NACK signal, when the terminal 200 transmits the sPUSCH of HARQ process ID#0 with UL sTTI#3, the interval of 3DL sTTI from the timing (DL sTTI#6) when the transmission/reception of the sPUSCH is completed. The later timing is DL sTTI#10. Therefore, the base station 100 transmits an ACK/NACK signal for the sPUSCH of HARQ process ID#0 with DL sTTI#10.

In addition, in the operation example 1-2, as in the operation example 1-1, the UL grant is the rearmost at the timing before (X-1) DL sTTI (3 DL sTTI in FIG. 7) or more from the timing of the boundary of the UL sTTI. Restrict to being placed in DL s TTI only. By doing so, as shown in FIG. 7, among DL sTTIs in one subframe, UL grants are arranged in four DL sTTIs and UL grants are not arranged in the remaining three DL sTTIs. By this means, it is possible to reduce the probability (false alert) of erroneously detecting a UL grant, as compared to the case where terminal 200 monitors UL grant in all DL sTTIs.

Further, in the operation example 1-2, the DL sTTI in which the ACK/NACK signal is transmitted/received is different from the DL sTTI in which the UL grant is transmitted/received, as in the operation example 1-1. In this way, the resources used for UL grant and the resources used for ACK/NACK signals are different, so that there is an advantage that the congestion degree of resources in which control signals are arranged is relaxed. By this means, it is possible to avoid limiting UL data allocation due to lack of control signal resources in DL.

However, in the operation example 1-2, unlike the operation example 1-1, since the number of DL sTTIs is 7/4 times the number of UL sTTIs, the ACK/NACK signal and the UL grant are all arranged in different DL sTTIs. I can't.

In the sTTI arrangement of FIG. 7, neither DL grant nor ACK/NACK signal is arranged in DL sTTI#11 and DL sTTI#18, whereas UL grant is formed in DL sTTI #10 and DL sTTI#17. Both ACK and NACK signals are arranged.

Therefore, in order to disperse the resources of the control signal, the base station 100 transmits the ACK/NACK signal immediately before the DL sTTI to which the UL grant having the same HARQ process ID as the HARQ process ID of the ACK/NACK signal is transmitted. May be adjusted to be transmitted in DL s TTI. FIG. 8 shows an operation example of adjusting the DL s TTI in which the ACK/NACK signal is arranged.

In FIG. 8, the ACK/NACK signal of HARQ process ID#0 arranged in DL sTTI#10 in FIG. 7 is the DL sTTI immediately preceding the DL sTTI#12 in which UL grant of HARQ process ID#0 is arranged. Placed at #11. Similarly, in FIG. 8, the ACK/NACK signal of HARQ process ID#4 arranged in DL sTTI#17 in FIG. 7 is one of DL sTTI#19 in which UL grant of HARQ process ID#4 is arranged. It is placed in the previous DL sTTI#18. As a result, control signals (UL grant and ACK/NACK signals) are distributed and arranged.

From the viewpoint of delay, the arrangement of the ACK/NACK signal may be 3 DL sTTI intervals from the sPUSCH of the same HARQ process ID, and 3 DL sTTI intervals of the next sPUSCH that may retransmit the same HARQ process ID. .. Therefore, the ACK/NACK signal of HARQ process ID#0 that was assigned to DL sTTI#10 is assigned to DL sTTI#11, and the ACK/NACK signal of HARQ process ID#4 that was assigned to DL sTTI#17 is changed. Even if it is placed in DL sTTI#18, there is no problem in terms of delay.

By delaying the ACK/NACK signal backward as shown in FIG. 8, the base station 100 can determine whether to perform adaptive retransmission or non-adaptive retransmission from the backward scheduling state. The flexibility of the scheduler of the station 100 can be improved.

<Operation example 1-3: UL data allocation (UL 7 symbols sTTIs and DL 2 symbols sTTIs)>
FIG. 9 illustrates transmission/reception timings of sPDCCH and sPUSCH in which UL grants that instruct transmission of UL data signals (sPUSCH) are placed, and transmission/reception of sPUSCH and ACK/NACK signals for the sPUSCH in operation example 1-3. An example of timing is shown.

In Operation Example 1-3, as shown in FIG. 9, the UL sTTI length is 7 symbols, the DL sTTI length is 2 symbols, and X=4. That is, in FIG. 9, there are seven DL sTTIs per subframe, and DL sTTIs #0 to #27 are assigned from subframe #0 to subframe #3. Further, in FIG. 9, there are two UL sTTIs per subframe, and UL sTTIs #0 to #7 are assigned from subframe #0 to subframe #3.

That is, in operation example 1-3, the number of DL sTTIs (7 per subframe) is 7/2 times the number of UL sTTIs (2 per subframe).

When X=4, the base station 100 and the terminal 200 allocate UL grant and sPUSCH, and sPUSCH and ACK/NACK signal at intervals of 3 DL sTTI or more, respectively, as in the operation example 1-1.

For example, regarding UL grant and sPUSCH, when the base station 100 transmits a UL grant of HARQ process ID #0 with DL sTTI#3, an interval of 3DL sTTI from the timing (DL sTTI#3) at which UL grant transmission/reception is completed. The later timing is DL sTTI#7. The terminal 200 transmits sPUSCH of HARQ process ID #0 at UL sTTI#2 which is the same timing as DL sTTI#7.

Similarly, for the sPUSCH and the ACK/NACK signal, when the terminal 200 transmits the sPUSCH of HARQ process ID#0 by UL sTTI#2, the interval of 3DL sTTI from the timing (DL sTTI#10) when the transmission/reception of the sPUSCH is completed. The later timing is DL sTTI#14. Therefore, the base station 100 transmits an ACK/NACK signal for the sPUSCH of HARQ process ID#0 in DL sTTI#14.

In addition, in the operation example 1-3, as in the operation example 1-1, the UL grant is the rearmost at the timing before (X-1) DL sTTI (3 DL sTTI in FIG. 9) or more from the timing of the boundary of the UL sTTI. Restrict to being placed in DL s TTI only. By doing so, as shown in FIG. 9, among DL sTTIs in one subframe, UL grants are arranged in two DL sTTIs and UL grants are not arranged in the remaining five DL sTTIs. By this means, it is possible to reduce the probability (false alert) of erroneously detecting a UL grant, as compared to the case where terminal 200 monitors UL grant in all DL sTTIs.

Further, in the operation example 1-3, the DL sTTI in which the ACK/NACK signal is transmitted/received and the DL sTTI in which the UL grant is transmitted/received are different, as in the operation example 1-1. In this way, the resources used for UL grant and the resources used for ACK/NACK signals are different, so that there is an advantage that the congestion degree of resources in which control signals are arranged is relaxed. By this means, it is possible to avoid limiting UL data allocation due to lack of control signal resources in DL.

However, in the operation example 1-3, since the number of DL sTTIs is 7/2 times the number of UL sTTIs, the ACK/NACK signal and the UL grant are all arranged in different DL sTTIs as in the operation example 1-2. I can't.

Therefore, in order to disperse the resources of the control signal, the base station 100 transmits the ACK/NACK signal immediately before the DL sTTI to which the UL grant having the same HARQ process ID as the HARQ process ID of the ACK/NACK signal is transmitted. May be adjusted to be transmitted in DL s TTI. FIG. 10 shows an operation example of adjusting the DL s TTI in which the ACK/NACK signal is arranged.

In FIG. 10, the ACK/NACK signal of HARQ process ID#0 arranged in DL sTTI#14 in FIG. 9 is the DL sTTI immediately preceding the DL sTTI#17 in which UL grant of HARQ process ID#0 is arranged. It is placed at #16 (DL sTTI, two behind DL sTTI #14). Similarly, in FIG. 10, the ACK/NACK signal of HARQ process ID#1 arranged in DL sTTI#17 in FIG. 9 is one of DL sTTI#20 in which UL grant of HARQ process ID#1 is arranged. It is placed in the front DL sTTI#19 (DL sTTI two behind DL sTTI#17). As a result, control signals (UL grant and ACK/NACK signals) are distributed and arranged.

From the viewpoint of delay, the arrangement of ACK/NACK signals is 3 DL sTTI intervals from the sPUSCH of the same HARQ process ID, and is the same as that of operation example 1-2, with the next sPUSCH that may retransmit the same HARQ process ID. DL sTTI interval is enough. Therefore, the ACK/NACK signal of HARQ process ID#0 that was assigned to DL sTTI#14 is assigned to DL sTTI#16, and the ACK/NACK signal of HARQ process ID#1 that was assigned to DL sTTI#17 is changed. Even if it is placed in DL sTTI#19, there is no problem in terms of delay.

Further, by delaying the ACK/NACK signal backward as shown in FIG. 10, the base station 100 can determine whether to perform adaptive retransmission or non-adaptive retransmission from the backward scheduling state. The flexibility of the scheduler of the base station 100 can be improved.

The operation examples 1-1 to 1-3 at the time of UL data allocation have been described above.

Next, an operation example when allocating DL data will be described. DL data allocation assumes Asynchronous HARQ. Further, the HARQ process ID is notified to the terminal 200 by the DL assignment.

In the following operation example, a case where continuous HARQ process IDs can be assigned to continuous DL sTTIs will be described, but the present invention is not limited to this.

<Operation example 2-1: DL data allocation (UL 7 symbols sTTIs and DL 3/4 symbols sTTIs)>
FIG. 11 shows transmission/reception timings of sPDCCH and sPDSCH in which DL assignments instructing transmission of DL data signal (sPDSCH) are arranged, and transmission/reception of sPDSCH and ACK/NACK signal for the sPDSCH in operation example 2-1. An example of timing is shown.

In Operation Example 2-1, as shown in FIG. 11, the UL sTTI length is 7 symbols, the DL sTTI length is 3/4 symbols, and X=4. That is, in FIG. 11, there are four DL sTTIs per subframe, and DL sTTIs #0 to #11 are assigned from subframe #0 to subframe #2. Further, in FIG. 11, there are two UL sTTIs per subframe, and UL sTTIs #0 to #5 are allocated from subframe #0 to subframe #2.

That is, in the operation example 2-1, as in the operation example 1-1, the number of DL sTTIs (4 per subframe) is twice the number of UL sTTIs (2 per subframe).

Regarding the DL assignment and the sPDSCH, the base station 100 transmits the sPDSCH designated by the DL assignment with the same DL sTTI as the DL sTTI that transmits and receives the DL assignment. For example, when transmitting the DL assignment of HARQ process ID #0 in DL sTTI#0, the base station 100 transmits sPDSCH in the same DL sTTI#0.

Further, for sPDSCH and ACK/NACK signal, in the case of X=4, the base station 100 and the terminal 200, based on the DL sTTI length, from the transmission/reception of sPDSCH, at least 4 DL sTTIs after the ACK/NACK signal for the sPDSCH. Start sending and receiving. That is, there is an interval of at least 3 DL sTTI (=X-1) from the completion of transmission/reception of sPDSCH to the start of transmission/reception of ACK/NACK signals. That is, the base station 100 and the terminal 200 transmit/receive an ACK/NACK signal at the first UL sTTI after an interval of 3 DL sTTI from the transmission/reception timing of sPDSCH.

For example, when the base station 100 transmits the sPDSCH of HARQ process ID#0 with DL sTTI#0, the timing after the 3DL sTTI interval from the timing (DL sTTI#0) when the transmission/reception of sPDSCH is completed is DL sTTI#4. Is. Therefore, the terminal 200 transmits the ACK/NACK signal for the sPDSCH of HARQ process ID#0 at UL sTTI#2, which is the same timing as DL sTTI#4.

Although HARQ process ID#0 is focused here, the same applies to the other HARQ process ID#2 to #4.

In FIG. 11, since the number of DL sTTIs is twice the number of UL sTTIs, the terminal 200 transmits two ACK/NACK signals for sPDSCHs received by two DL sTTIs per UL sTTI. At that time, the terminal 200 transmits multiple ACKs/NACKs by, for example, multiplexing or bundling and using UL resources.

In LTE/LTE-Advanced, the start position of the UL resource from which the UE transmits an ACK/NACK signal is indicated by a higher layer parameter called N1_PUCCH, and the offset amount from the start position is obtained from the (E)CCE number.

On the other hand, in the operation example 2-1, the terminal 200, regarding the sPDSUC and the ACK/NACK signal, the plurality of DL sTTIs used for receiving the sPDSCH in which the corresponding ACK/NACK signals are transmitted in the same UL sTTI. Among them, the transmission position of the ACK/NACK signal may be specified from the DL assignment received in the DL sTTI with the larger DL sTTI number (that is, the DL sTTI in the rear). This is because in the latter half of DL sTTI, the scheduler can later change the resource allocation in consideration of the ACK/NACK resources, and the scheduling flexibility increases. For example, in FIG. 11, terminal 200 has the largest DL sTTI number among DL sTTI#1 and DL sTTI#2 used for receiving sPDSCHs corresponding to ACK/NACK signals transmitted in UL sTTI#3. The transmission position of the ACK/NACK signal is specified from the DL assignment received on the sPDCCH of DL sTTI#2.

In addition, the terminal 200 actually uses one DL sTTI among a plurality of DL sTTIs used for receiving the sPDSCH in which the corresponding ACK/NACK signal is transmitted with the same UL sTTI for the sPDSCH and the ACK/NACK signal. When the sPDSCH is received, the transmission position of the ACK/NACK signal is specified from the DL assignment received by the DL sTTI.

It should be noted that the transmission position of the ACK/NACK signal is determined from N1_PUCCH notified by the higher layer, from the shift amount based on DL sTTI and the shift amount based on the CCE number of DL assignment. It is assumed that the shift amount based on DL sTTI is predetermined. It is also possible that N1_PUCCH is reported in the upper layer for each DL sTTI.

<Operation example 2-2: DL data allocation (UL 3/4 symbols sTTIs and DL 2 symbols sTTIs)>
FIG. 12 is a transmission/reception timing of sPDCCH and sPDSCH in which DL assignment for instructing transmission of a DL data signal (sPDSCH) is arranged, and transmission/reception of sPDSCH and ACK/NACK signal for the sPDSCH in operation example 2-2. An example of timing is shown.

In operation example 2-2, as shown in FIG. 12, the UL sTTI length is 3/4 symbols, the DL sTTI length is 2 symbols, and X=4. That is, in FIG. 12, there are seven DL sTTIs per subframe, and DL sTTIs #0 to #13 are assigned from subframe #0 to subframe #1. Further, in FIG. 12, there are four UL sTTIs per subframe, and UL sTTIs #0 to #7 are assigned from subframe #0 to subframe #1.

That is, in the operation example 2-2, as in the operation example 1-2, the number of DL sTTIs (7 per subframe) is 7/4 times the number of UL sTTIs (4 per subframe).

Regarding the DL assignment and the sPDSCH, the base station 100 transmits the sPDSCH designated by the DL assignment with the same DL sTTI as the DL sTTI that transmits and receives the DL assignment. For example, when transmitting the DL assignment of HARQ process ID #0 in DL sTTI#0, the base station 100 transmits sPDSCH in the same DL sTTI#0.

Further, for sPDSCH and ACK/NACK signal, in the case of X=4, the base station 100 and the terminal 200, based on the DL sTTI length, from the transmission/reception of the sPDSCH, at least 4 DL sTTIs after the ACK/NACK signal for the sPDSCH. Start sending and receiving. That is, there is an interval of at least 3 DL sTTI (=X-1) from the completion of transmission/reception of sPDSCH to the start of transmission/reception of ACK/NACK signals. That is, the base station 100 and the terminal 200 transmit/receive an ACK/NACK signal at the first UL sTTI after an interval of 3 DL sTTI from the transmission/reception timing of sPDSCH.

For example, when the base station 100 transmits the sPDSCH of HARQ process ID#0 with DL sTTI#0, the timing after the 3DL sTTI interval from the timing (DL sTTI#0) when the transmission/reception of the sPDSCH is completed is DL sTTI#4. Is. Since the timing of DL sTTI#4 does not coincide with the UL sTTI boundary, the terminal 200 delays the transmission of the ACK/NACK signal until UL sTTI#3, which is the first UL sTTI behind the timing of DL sTTI#4. , UL sTTI#3 transmits ACK/NACK signal for sPDSCH of HARQ process ID#0.

Further, in FIG. 12, the number of DL sTTIs is 7/4 times the number of UL sTTIs, so that the terminal 200 transmits two DL sTTI ACK/NACK signals per UL sTTI, and one DL per sTTI. In some cases, ACK/NACK signal of sTTI is transmitted. In FIG. 12, two DL sTTI ACK/NACK signals are transmitted in UL sTTI #3, #4, and #5, respectively, and one DL sTTI ACK/NACK signal is transmitted in UL sTTI #6. In this way, since the maximum value of the number of ACK/NACK signals to be transmitted differs for each UL sTTI, the terminal 200 can change the format used for transmitting the ACK/NACK signal for each UL sTTI.

Further, in FIG. 12, some ACK/NACK signals for the DL data signal (sPDSCH) assigned to the same subframe#0 are transmitted in the same subframe#0 as sPDSCH, and the remaining ACK/NACK signals are subframes. It has been sent in #1. That is, ACK/NACK signals for sPDSCH assigned to the same subframe #0 are transmitted in different subframes #0 and #1. This shortens the feedback delay for the DL data signal and makes the Latency reduction more efficient.

Note that, for example, when the application such as interference control, CoMP, and D2D is determined and used in subframe units, it is desirable that the usage method in subframe units is fixed. Therefore, as shown in FIG. 13A or FIG. 13B, all ACK/NACK signals for the DL data signal (sPDSCH) assigned to the same subframe may be transmitted in the same subframe. That is, the base station 100 and the terminal 200 transmit/receive an ACK/NACK signal for each of a plurality of sPDSCHs transmitted/received in the same subframe, using a plurality of UL sTTIs in one subframe.

In FIGS. 13A and 13B, since the subframe in which the ACK/NACK signal for the sPDSCH transmitted in the final DL sTTI #6 of the DL subframe #0 is transmitted is subfraem #1, other DL sTTI in DL subframe #0 All are transmitted in subframe #1, including the ACK/NACK signal for the sPDSCH transmitted in.

As a first implementation method, the timing of the ACK/NACK signal shown in FIG. 12 is shifted backward by 1 UL sTTI. Further, as a second method of realization, X=4 is changed to X=6. The value of X is set so that the ACK/NACK signal for the DL data signal (sPDSCH) assigned to the same subframe can be transmitted in the same subframe. This has the advantage that UL subframe interference control, CoMP, D2D, etc., can be easily assigned in subframe units.

Although the number of ACK/NACK signals transmitted in UL sTTI differs between the first and second methods, the maximum and minimum values of the number of ACK/NACK signals are the same.

<Operation example 2-3: DL data allocation (UL 7 symbols sTTIs and DL 2 symbols sTTIs)>
FIG. 14 is a transmission/reception timing of sPDCCH and sPDSCH in which DL assignment for instructing transmission of DL data signal (sPDSCH) is arranged, and transmission/reception of sPDSCH and ACK/NACK signal for the sPDSCH in operation example 2-3. An example of timing is shown.

In the operation example 2-3, as shown in FIG. 14, the UL sTTI length is 7 symbols, the DL sTTI length is 2 symbols, and X=4. That is, in FIG. 14, there are seven DL sTTIs per subframe, and DL sTTIs #0 to #13 are assigned from subframe #0 to subframe #1. Further, in FIG. 14, there are two UL sTTIs per subframe, and UL sTTIs #0 to #3 are assigned from subframe #0 to subframe #1.

That is, in the operation example 2-3, the number of DL sTTIs (7 per subframe) is 7/2 times the number of UL sTTIs (2 per subframe), as in the operation example 1-3.

Regarding the DL assignment and the sPDSCH, the base station 100 assigns the sPDSCH designated by the DL assignment to the same DL sTTI as the DL sTTI that transmits and receives the DL assignment. For example, when transmitting the DL assignment of HARQ process ID #0 in DL sTTI#0, the base station 100 transmits sPDSCH in the same DL sTTI#0.

Further, for sPDSCH and ACK/NACK signal, in the case of X=4, the base station 100 and the terminal 200, based on the DL sTTI length, from the transmission/reception of the sPDSCH, at least 4 DL sTTIs after the ACK/NACK signal for the sPDSCH. Start sending and receiving. That is, there is an interval of at least 3 DL sTTI (=X-1) from the completion of transmission/reception of sPDSCH to the start of transmission/reception of ACK/NACK signals. That is, the base station 100 and the terminal 200 transmit/receive an ACK/NACK signal at the first UL sTTI after an interval of 3 DL sTTI from the transmission/reception timing of sPDSCH.

For example, when the base station 100 transmits the sPDSCH of HARQ process ID#0 with DL sTTI#0, the timing after the 3DL sTTI interval from the timing (DL sTTI#0) when the transmission/reception of sPDSCH is completed is DL sTTI#4. Is. Since the timing of DL sTTI#4 does not match the UL sTTI boundary, the terminal 200 delays the transmission of the ACK/NACK signal until UL sTTI#2, which is the first UL sTTI behind the timing of DL sTTI#4. , UL sTTI#2 transmits ACK/NACK signal for sPDSCH of HARQ process ID#0.

Also, in FIG. 14, the number of DL sTTIs is 7/2 times the number of UL sTTIs, so that the terminal 200 transmits four DL sTTI ACK/NACK signals per UL sTTI and three DL per sTTI. In some cases, ACK/NACK signal of sTTI is transmitted. In FIG. 14, four DL sTTI ACK/NACK signals are transmitted in UL sTTI #2, and three DL sTTI ACK/NACK signals are transmitted in UL sTTI #3. In this way, since the maximum value of the number of ACK/NACK signals to be transmitted differs for each UL sTTI, the terminal 200 can change the format used for transmitting the ACK/NACK signal for each UL sTTI.

The operation example 2-1 to the operation example 2-3 at the time of assigning DL data have been described above.

In this way, according to the present embodiment, base station 100 and terminal 200 transmit and receive downlink signals (sPDCCH, sPDSCH, ACK/NACK signals) using DL sTTI with a TTI length shorter than TTI, and from TTI. Also transmits and receives upstream signals (sPUSCH, ACK/NACK signals) using UL sTTI with a shortened TTI length. At that time, if the DL sTTI length is shorter than the UL sTTI length, the base station 100 and the terminal 200 transmit and receive the uplink signal with UL sTTI after a predetermined interval set based on the DL sTTI length from the transmission timing of the downlink signal. To do. Also, when the determined transmission/reception timing does not match the UL sTTI boundary, the base station 100 and the terminal 200 delay the transmission/reception timing until the timing matches the UL sTTI boundary.

By this means, even if the DL sTTI length and the UL sTTI length are different, the base station 100 and the terminal 200 can start signal transmission/reception from the respective boundaries of the DL sTTI and the UL sTTI. Therefore, according to the present embodiment, it is possible to appropriately set the timings of data allocation, data transmission/reception, and feedback when sTTI lengths differ between DL and UL.

In this embodiment, an example in which the ACK/NACK signal is assigned to the ACK/NACK resource is shown, but the ACK/NACK resource may be a PUCCH (Physical Uplink Control Channel) resource. Further, there is also a method of multiplexing an ACK/NACK signal on the UL data signal and transmitting the UL data signal when the UL data signal is assigned. In this case, the terminal 200 transmits an ACK/NACK signal for the sPDSCH transmitted in a plurality of DL sTTIs with the UL sTTI if at least one of the plurality of UL sTTIs is assigned with a UL data signal. Good. By doing so, there is an advantage that the PUCCH format and the PUSCH format do not coexist in the subframe, and the terminal 200 can transmit the signal in the subframe in one format.

Further, the operation of the present disclosure can be applied to a combination of the DL sTTI length and the UL sTTI length, other than the combination shown in the operation example of the present embodiment.

(Embodiment 2)
The base station and terminal according to the present embodiment have the same basic configuration as base station 100 and terminal 200 according to Embodiment 1, and will be described with reference to FIGS. 4 and 5.

In the present embodiment, the DL sTTI length and the UL sTTI length are different, and when the DL sTTI length is shorter than the UL sTTI length, the base station 100 and the terminal 200 allocate data (based on the DL sTTI length and absolute time). UL grant and DL assignment in sPDCCH), data transmission/reception (sPUSCH, sPDSCH), and feedback (ACK/NACK signal) transmission/reception timing are determined.

The absolute time is a fixed length time in consideration of processing delay or time required for communication with an upper layer.

Further, as in the case of Embodiment 1, if the UL timing determined based on the DL sTTI length does not match the UL sTTI boundary, the base station 100 and the terminal 200 delay until the UL sTTI boundary coincides.

Specifically, for DL data, the base station 100 and the terminal 200 transmit an ACK/NACK signal for the sPDSCH with UL sTTI after a predetermined interval set based on the DL sTTI length and absolute time from the transmission/reception timing of the sPDSCH. Send and receive.

Regarding UL data, the base station 100 and the terminal 200 are assigned with the UL grant in the UL sTTI after a predetermined interval set based on the DL sTTI length and the absolute time from the transmission/reception timing of the sPDCCH including the UL grant. Send and receive sPUSCH. Also, the base station 100 and the terminal 200 transmit/receive an ACK/NACK signal for the sPUSCH with a DL sTTI after a predetermined interval set based on the DL sTTI length and absolute time from the sPUSCH transmission/reception timing.

For example, the base station 100 and the terminal 200 receive the second signal at a timing after the time obtained by adding the absolute time (Y) to the interval of a predetermined number (X) of DL sTTIs from the transmission/reception timing of the first signal. May be sent and received. Specifically, the base station 100 and the terminal 200 define the timing of data allocation, data transmission/reception, and feedback (transmission timing of the second signal with respect to the first signal) as follows. Here, the absolute time is represented by Y msec.
Timing for DL data
DL assignment in sPDCCH-sPDSCH: same sTTI
sPDSCH-ACK/NACK feedback: at least after X DL sTTIs + Y msec
Timing for UL data
UL grant in sPDCCH-sPUSCH: At least after X DL sTTIs + Y msec
sPUSCH-ACK/NACK feedback: After at least X DL sTTIs + Y msec

It should be noted that "at least X DL sTTIs + Y msec" means the second signal (above sPDSCH, ACK/ACK/ACK/ACK/ACK after completion of transmission/reception of the first signal (above DL assignment, sPDSCH, UL grant or sPUSCH). There is at least (X-1) sTTI + Y msec interval until NACK feedback, sPUSCH or ACK/NACK feedback) transmission and reception is started, and the second signal should be assigned to the first sTTI after that interval. Show.

Hereinafter, operations of data allocation, data transmission/reception, and feedback in the base station 100 and the terminal 200 will be described in detail.

In the following, the UL sTTI length is 7 symbols, the DL sTTI length is 3/4 symbols, and X=4, as in the operation example 1-1 and the operation example 2-1 of the first embodiment. The absolute time Y is 0.5 msec.

FIG. 15 shows an example of transmission/reception timings of sPDCCH and sPUSCH in which UL grants for instructing transmission of UL data signals (sPUSCH) and transmission/reception timings of sPUSCH and ACK/NACK signals for the sPUSCH.

Regarding UL grant and sPUSCH, in the case of X=4, the base station 100 and the terminal 200, based on the DL sTTI length and the absolute time Y, are at least 4 DL sTTIs+0.5 msec after transmitting/receiving UL grant (sPDCCH), Start sending and receiving. That is, there is at least an interval of 3 DL sTTI (=X-1)+0.5 msec from the completion of transmission/reception of UL grant to the start of transmission/reception of sPUSCH. That is, the base station 100 and the terminal 200 transmit/receive sPUSCH in the first UL sTTI after the interval of 3 DL sTTI+0.5 msec.

Similarly, for sPUSCH and ACK/NACK signals, when X=4, the base station 100 and the terminal 200 refer to the DL sTTI length and the absolute time Y, and at least 4 DL sTTIs+0.5 msec after transmission/reception of sPUSCH. Start sending and receiving ACK/NACK signals to sPUSCH. That is, there is at least an interval of 3 DL sTTI + 0.5 msec from the completion of transmission/reception of sPUSCH to the start of transmission/reception of ACK/NACK signals. That is, the base station 100 and the terminal 200 transmit/receive an ACK/NACK signal at the first DL sTTI after an interval of 3 DL sTTI+0.5 msec from the sPUSCH transmission/reception timing.

In addition, FIG. 16 illustrates an example of transmission/reception timing of sPDCCH and sPDSCH in which DL assignment for instructing transmission of DL data signal (sPDSCH) is arranged, and transmission/reception timing of sPDSCH and ACK/NACK signal for the sPDSCH. ..

Regarding the DL assignment and the sPDSCH, the base station 100 transmits the sPDSCH designated by the DL assignment with the same DL sTTI as the DL sTTI that transmits and receives the DL assignment.

For sPDSCH and ACK/NACK signals, when X=4, the base station 100 and the terminal 200 refer to the DL sTTI length and the absolute time Y, and at least 4 DL sTTIs + 0.5 msec after the sPDSCH transmission/reception. Start sending and receiving ACK/NACK signal for. That is, there is an interval of at least 3 DL sTTI (=X-1)+0.5 msec from the completion of transmission/reception of sPDSCH to the start of transmission/reception of ACK/NACK signals. That is, the base station 100 and the terminal 200 transmit/receive an ACK/NACK signal with the first UL sTTI after an interval of 3 DL sTTI+0.5 msec from the transmission/reception timing of sPDSCH.

By doing so, the base station 100 and the terminal 200 can secure the processing delay in each device or the time required for communication with the upper layer.

[variation]
The base station 100 and the terminal 200 may define the timing of data allocation, data transmission/reception, and feedback (transmission timing of the second signal with respect to the first signal) as follows.

Timing for DL data:
DL assignment in sPDCCH-sPDSCH: same sTTI
sPDSCH-ACK/NACK feedback: At least Max(X-1 DL sTTIs, Y msec) interval
Timing for UL data
UL grant in sPDCCH-sPUSCH: At least Max(X-1 DL sTTIs, Y msec) interval
sPUSCH-ACK/NACK feedback: At least Max(X-1 DL sTTIs, Y msec) interval

For Max(X-1 DL sTTIs, Y msec), the larger one of X-1 DL sTTIs and Y msec is selected.

That is, the base station 100 and the terminal 200 receive the first UL sTTI after a larger time of the predetermined number of DL sTTI intervals (X-1) and the absolute time Y from the first signal transmission/reception timing. Send and receive the second signal.

By doing this, when the sTTI length is longer than the absolute time Y, the processing delay in each device or the time required for communication with the upper layer can be secured only by the sTTI length, and the absolute time Y is not set. Since the interval can be set only by the sTTI length, it is possible to avoid setting an extra delay. Further, when the sTTI length is shorter than the absolute time Y, it is possible to sufficiently secure the processing delay in each device or the time required for communication with the upper layer.

(Embodiment 3)
The base station and terminal according to the present embodiment have the same basic configuration as base station 100 and terminal 200 according to Embodiment 1, and will be described with reference to FIGS. 4 and 5.

The first and second embodiments assume that the base station 100 and the terminal 200 can use all sTTIs. However, the area used for conventional terminals (terminals that do not support sTTI), the PDCCH area used for the common search space, or CRS (Cell-specific Reference Signal), DMRS (Demodulation Reference Signal), CSI-RS Due to the arrangement of reference signals such as (Channel State Information Reference Signal) and SRS (Sounding Reference Signal), resources available for transmitting and receiving data and control signals in the sTTI area are reduced. Therefore, it is considered that the sTTI is not used for transmitting/receiving the data and the control signal, or that the adjacent sTTIs are combined and used as one sTTI. In addition, DL and UL have different sTTI numbers because the amounts of control signals and reference signals are different.

Therefore, in the present embodiment, a method of setting the timing of data allocation, data transmission/reception, and feedback when the usable sTTI differs for each subframe will be described.

In the base station 100 and the terminal 200, all sTTIs in a subframe can be used, adjacent sTTIs are not combined into one sTTI, and the subframe with the largest number of sTTIs is used as the DL reference subframe. .. The transmission/reception timing of data allocation (UL grant and DL assignment in sPDCCH), data transmission/reception (sPUSCH, sPDSCH), and feedback (ACK/NACK signal) is determined based on the DL sTTI length in the DL reference subframe.

Further, as in the case of Embodiment 1, if the UL timing determined based on the DL sTTI length does not match the UL sTTI boundary, the base station 100 and the terminal 200 delay until the UL sTTI boundary coincides.

Specifically, the base station 100 and the terminal 200 set the timing of data allocation, data transmission/reception, and feedback (transmission timing of the second signal with respect to the first signal) as described below, as in the first embodiment. Stipulate.
Timing for DL data
DL assignment in sPDCCH-sPDSCH: same sTTI
sPDSCH-ACK/NACK feedback: at least after X DL sTTIs
Timing for UL data
UL grant in sPDCCH-sPUSCH: at least after X DL sTTIs
sPUSCH-ACK/NACK feedback: at least after X DL sTTIs

Note that "at least X DL sTTIs" means the second signal (above sPDSCH, ACK/NACK feedback, after the transmission and reception of the first signal (above DL assignment, sPDSCH, UL grant or sPUSCH) is completed. It indicates that there is an interval of at least (X-1)sTTI until the transmission/reception of sPUSCH or ACK/NACK feedback) is started, and the second signal is assigned to the first sTTI after the interval.

In addition, in the present embodiment, base station 100 has a predetermined interval before the timing of receiving an upstream signal (sPUSCH) in a subframe in which the number of DL sTTIs that can be used for signal allocation is smaller than the subframe that is the DL reference. When DL sTTI (timing defined above) cannot be used for signal allocation, the downlink signal (sPDCCH) is transmitted at the most backward DL sTTI before DL sTTI that cannot be used for signal allocation. Similarly, the base station 100, in a subframe in which the number of DL sTTIs that can be used for signal allocation is less than the reference subframe, the DL sTTI (above described) after a predetermined interval from the UL sTTI timing at which the uplink signal (sPUSCH) is received. If the specified timing) cannot be used for signal allocation, the ACK/NACK signal for the upstream signal is transmitted in the first DL sTTI after the DL sTTI that cannot be used for signal allocation.

Hereinafter, operations of data allocation, data transmission/reception, and feedback in the base station 100 and the terminal 200 will be described in detail.

[Operation Example 3-1]
FIG. 17 shows an example of transmission/reception timings of sPDCCH and sPUSCH in which UL grants for instructing transmission of UL data signal (sPUSCH) are arranged, and transmission/reception timings of sPUSCH and ACK/NACK signal for the sPUSCH.

As shown in FIG. 17, the UL sTTI length is 3/4 symbols, the DL sTTI length is 2 symbols, and X=4, as in the operation example 1-2 (see FIG. 7) of the first embodiment. Also, the base station 100 and the terminal 200 cannot use the sixth DL sTTI (DL sTTI#5, #12, #19, #26) of all subframes.

Regarding UL grant and sPUSCH, when X=4, sPUSCH transmitted by UL sTTI#5 has the same timing as UL sTTI#5 in the subframe shown in operation example 1-2 (subframe which is the reference of DL). Allocated by UL grant transmitted in DL sTTI#5 from DL sTTI#9 to 3 DL sTTI#5 before. However, in FIG. 17, DLs TTI#5 cannot be used. Therefore, the base station 100 transmits the UL grant in DL sTTI#4, which is one before DL sTTI#5. Similarly, the base station 100 sends DL grant indicating DL sTTI#11 and DL sTTI#12 and #19, which are scheduled to be transmitted in DL sTTI#12 and #19, to the UL sTTI#9 and UL sTTI#13. , Send with #18.

In addition, for X=4 for the sPUSCH and ACK/NACK signals, in the subframe shown in the operation example 1-2 (subframe which is the reference of DL), the ACK/NACK signal for sPUSCH of UL sTTI#4 is UL sTTI It was transmitted from DL sTTI#8 at the same timing as #4 to DL sTTI#12 after 3DL sTTI intervals. However, in FIG. 17, DL sTTI #12 cannot be used. Therefore, the base station 100 delays the transmission timing of the ACK/NACK signal and transmits it with DL sTTI#13. Similarly, when X=4, in the operation example 1-2, the ACK/NACK signal for sPUSCH of UL sTTI#8, #12 is DL sTTI#15, #22 at the same timing as UL sTTI#8, #12. From 3 DL sTTI #19, #26 after the DL sTTI interval. However, in FIG. 17, DL sTTI #19 and #26 cannot be used. Therefore, the base station 100 delays the transmission timing of the ACK/NACK signal and transmits the DL sTTI #20 and #27.

Also, in FIG. 17, the number of DL sTTIs is larger than the number of UL sTTIs, so even if some DL sTTIs cannot be used, there is no effect on the number of UL HARQ processes. However, if there are many DL sTTIs that cannot be used or if consecutive DL sTTIs cannot be used, the amount of delay increases, so it is necessary to increase the number of UL HARQ processes.

[Operation Example 3-2]
In the operation example 3-2, the operation when the UL sTTI length and the DL sTTI length are the same will be described.

FIG. 18 shows an example of transmission/reception timings of sPDCCH and sPUSCH in which UL grants for instructing transmission of UL data signal (sPUSCH) are arranged, and transmission/reception timing of sPUSCH and ACK/NACK signal for the sPUSCH.

As shown in FIG. 18, both the UL sTTI length and the DL sTTI length are set to 3/4 symbols and X=4. That is, one subframe is divided into 4s TTI. Also, the base station 100 and the terminal 200 cannot use the third DL sTTI (DL sTTI#2, #10, #18) of the even-numbered subframe. That is, the number of DL sTTIs that can be used for signal assignment using sTTI in even-numbered subframes is smaller than that in odd-numbered subframes (subframes that serve as DL references).

When all DL sTTIs can be used, the minimum UL HARQ process ID number is 8 at X=4. However, in the operation example 3-2, since some DL sTTIs cannot be used, the delay of UL allocation and ACK/NACK feedback becomes long, so the minimum number of HARQ process IDs is 9.

Regarding UL grant and sPUSCH, when X=4, if all DL sTTI can be used, sPUSCH transmitted in UL sTTI#6 is DL sTTI#6 to 3DL sTTI at the same timing as UL sTTI#6. Assigned by UL grant transmitted in DL sTTI#2 before the interval. However, in FIG. 18, DLs TTI#2 of subframe#0 cannot be used. Therefore, the base station 100 transmits the UL grant in DL sTTI#1 which is one before DL sTTI#2. Similarly, the base station 100 uses the DL sTTI#9, which is the UL sTTI #14 and UL sTTI #22, which are scheduled to be transmitted in the DL sTTI#10 and #18 shown in FIG. , Send with #17.

Regarding sPUSCH and ACK/NACK signals, when X=4, if all DL sTTI can be used, the ACK/NACK signal for sPUSCH of UL sTTI#6 is DL with the same timing as UL sTTI#6. Sent on DL sTTI #10 after 3 DL sTTI intervals from sTTI#6. However, in FIG. 18, DL sTTI #10 cannot be used. Therefore, the base station 100 delays the transmission timing of the ACK/NACK signal and transmits it with DL sTTI#11. Similarly, in the case of X=4, if all DL sTTIs can be used, the ACK/NACK signal for sPUSCH of UL sTTI#14 is 3DL sTTI interval after DL sTTI#14 at the same timing as UL sTTI#14. It was sent in DL sTTI #18. However, in FIG. 18, DL sTTI #18 cannot be used. Therefore, the base station 100 delays the transmission timing of the ACK/NACK signal and transmits it with DL sTTI#19.

The operation example 3-1 and the operation example 3-2 have been described above.

In this way, according to the present embodiment, base station 100 and terminal 200 use DL sTTI as a reference in the same manner as in Embodiment 1 even if there is a DL sTTI to which a signal cannot be assigned within a DL subframe. As data allocation, data transmission/reception, and feedback timing are determined. Further, when the determined DL timing is DL sTTI to which the above signal is not assigned, the base station 100 and the terminal 200 have DL signal (data signal or ACK/NACK signal) at a timing before or after the timing. To send.

By this means, base station 100 and terminal 200 can start signal transmission/reception from the respective boundaries of DL sTTI and UL sTTI in the same manner as in Embodiment 1, even if the number of DL sTTIs differs between subframes. .. Therefore, according to the present embodiment, it is possible to appropriately set the timing of data allocation, data transmission/reception, and feedback when the TTI length is shortened.

If the first DL sTTI in the DL subframe cannot be used, PDCCH can be used instead. Since the base station 100 transmits the control signal and the ACK/NACK signal assigned to the sTTI on the PDCCH, no delay occurs, which has the advantage of not affecting the number of HARQ process IDs.

(Embodiment 4)
The base station and terminal according to the present embodiment have the same basic configuration as base station 100 and terminal 200 according to Embodiment 1, and will be described with reference to FIGS. 4 and 5.

When operating with sTTI length, it may be possible to return to the normal TTI length due to reasons such as poor line quality or unnecessary latency reduction. Therefore, in the present embodiment, the operation when switching from the sTTI length to the normal TTI length (1 subframe) will be described.

As a method of returning to a normal TTI, a method of allocating with a normal TTI length by CSS (Common search space) or a method of instructing the MAC layer to change to a normal TTI length can be considered. At this time, regarding the HARQ process ID used in sTTI, there are a method of continuing the normal TTI and a method of not continuing it.

When the HARQ process ID is not continued, the base station 100 and the terminal 200 erase the signal of the HARQ buffer and newly start communication as new data.

On the other hand, in the case of continuing the HARQ process ID, in DL, the base station 100 instructs the terminal 200 to continue the HARQ process ID with a DL assignment having a normal TTI length.

Further, in the case of UL, since the HARQ process ID is not notified to the terminal 200, the base station 100 and the terminal 200 need a mechanism to share the UL HARQ process ID in advance between the sTTI and the normal TTI. As a mechanism for sharing the UL HARQ process ID, the terminal 200 associates sTTI with TTI based on the subframe that received the TTI length switching.

FIG. 19 shows an operation example of switching between sTTI and TTI in subframe #1.

In FIG. 19, sTTI is applied to subframe #0, and terminal 200 detects UL grant of HARQ process ID #0, #1, #2, #3. Further, it is assumed that terminal 200 detects a normal TTI UL grant on the PDCCH of subframe #1.

In this case, with respect to HARQ process IDs #0, #1, #2, and #3 that operate in sTTI, terminal 200 performs sPUSCH transmission processing in sTTI operation even in UL in subframe #1. At this time, the base station 100 may transmit the ACK/NACK signal for sPUSCH transmitted in sTTI in subframe #2. When NACK is transmitted in subframe #1, terminal 200 can retransmit sPUSCH in subframe #3 (not shown). By doing so, it is possible to effectively use resources until PUSCH transmission is switched to normal TTI.

In addition, even if the base station 100 cancels the transmission of the ACK/NACK signal in subframe#2, causes the terminal 200 to recognize all as ACK, and allows only the adaptive retransmission using the normal TTI. Good.

In the first DL sTTI of Subframe #1, UL HARQ process ID #4 can be transmitted if the operation in sTTI is continued. Therefore, terminal 200 recognizes that UL grant of UL HARQ process ID #4 is transmitted on PDCCH of subframe #1 with reference to subframe #1, and according to the LTE/LTE-Advanced regulations, after 4 subframes (3 DL subframe Send PUSCH with HARQ process ID #4 in subframe #5 (after the interval). Further, terminal 200 recognizes that the UL grant of HARQ process ID #5 is transmitted in the PDCCH of the next subframe #2.

In this way, the base station 100 and the terminal 200 use sTTI in HARQ process ID#0 to #3, and switch from sTTI to TTI after UL HARQ process ID#4. That is, the base station 100 and the terminal 200 use a common HARQ process ID when using sTTI (DL sTTI and UL sTTI) and when using TTI.

By doing so, even if the sTTI is switched to the normal TTI, the base station 100 and the terminal 200 can continue the retransmission process of the UL data signal. Further, the base station 100 and the terminal 200 do not need to have double HARQ buffers for sTTI and TTI, and thus the buffer amount can be reduced.

The embodiments of the present disclosure have been described above.

In addition, although the timing of HARQ based on FDD has been described in the above embodiment, the timing of HARQ based on TDD can also be applied. When applying the present disclosure to the timing of HARQ based on TDD, bundling between subframes may be further applied.

Further, although cases have been described with the above embodiments where the signal transmission/reception timing is determined based on the DL sTTI length, the signal transmission/reception timing may be determined based on the UL sTTI length.

Further, in the above embodiment, X=4 has been described, but the value of X may be another value.

Further, in the above-described embodiment, the UL transmission timing is also adjusted by Timing Advanced (TA). Therefore, the actual UL transmission timing may be determined so as to start transmission earlier by a predetermined TA in addition to the timing defined in the above embodiment.

Further, although the UL grant is limited to be transmitted from only a specific DL sTTI in Embodiment 1, the present invention is not limited to this in other embodiments. The UL grant may be transmitted at least X DL sTTI or more before the UL sTTI that can transmit the PUSCH, and UL grants for one UL sTTI may be transmitted from multiple DL sTTIs. In this case, although DL sTTI for monitoring UL grant in terminal 200 increases, there is an advantage that control signals can be easily dispersed.

In addition, shortening the TTI length can be applied not only to systems that extend LTE, but also to systems realized with a new frame format called New RAT (Radio Access Technology).

Further, although cases have been described with the above embodiment as examples where an aspect of the present disclosure is configured by hardware, the present disclosure can also be implemented by software in cooperation with hardware.

Each functional block used in the description of the above embodiments is typically realized as an LSI which is an integrated circuit having an input terminal and an output terminal. The integrated circuit may control each of the functional blocks used in the description of the above embodiments, and may include an input terminal and an output terminal. These may be individually made into one chip, or may be made into one chip so as to include some or all of them. The name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

Further, the method of circuit integration is not limited to LSI, and it may be realized by a dedicated circuit or a general-purpose processor. A field programmable gate array (FPGA) that can be programmed after the LSI is manufactured, or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

Furthermore, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. The application of biotechnology is possible.

A base station according to the present disclosure includes a transmitter that transmits a downlink signal using a first sTTI (short TTI) on the downlink, which has a shorter TTI length than the TTI (Transmission Time Interval), and an uplink that has a shorter TTI length than the TTI. And a receiving unit that receives an upstream signal using the second sTTI of the line, and when the length of the first sTTI is shorter than the second sTTI, the receiving unit determines the length of the first sTTI from the transmission timing of the downstream signal. Uplink signals are received at the second sTTI after a predetermined interval set as a reference.

In the base station of the present disclosure, the receiving unit receives the upstream signal at the first second sTTI after the interval of the predetermined number of first sTTIs from the transmission timing of the downstream signal.

In the base station of the present disclosure, the reception unit delays the reception timing of the uplink signal when the same timing as the timing after the predetermined number of first sTTIs does not match the boundary of the second sTTI from the transmission timing of the downlink signal.

In the base station of the present disclosure, the downlink signal includes downlink allocation control information indicating allocation of the downlink data signal, and the receiving unit receives the downlink data at the second sTTI after a predetermined interval from the timing of the first sTTI that transmitted the downlink data signal. Receive the ACK/NACK signal for the signal.

In the base station of the present disclosure, the downlink signal includes uplink allocation control information indicating allocation of the uplink signal, and the transmission unit ACKs/receives the uplink signal at the first sTTI after a predetermined interval from the timing of the second sTTI at which the uplink signal is received. Send a NACK signal.

In the base station of the present disclosure, the first sTTI for transmitting the uplink allocation control information and the first sTTI for transmitting the ACK/NACK signal are different.

In the base station of the present disclosure, the transmission unit transmits the ACK/NACK signal to the first sTTI immediately before the first sTTI at which the uplink allocation control information of the same HARQ process ID as the HARQ process ID of the ACK/NACK signal is transmitted. Send with.

In the base station of the present disclosure, the receiving unit receives the ACK/NACK signal for each of the plurality of downlink signals transmitted in the same subframe, in the plurality of second sTTIs in one subframe.

In the base station according to the present disclosure, the receiving unit receives the uplink signal at the first second sTTI after a lapse of time obtained by adding the absolute time to the interval of the first sTTI of the predetermined number from the transmission timing of the downlink signal.

In the base station according to the present disclosure, the receiving unit receives the uplink signal at the first second sTTI after the elapse of a larger time of the predetermined number of first sTTI intervals and the absolute time from the transmission timing of the downlink signal.

In the base station of the present disclosure, the transmission unit sets a predetermined interval based on the length of the first sTTI forming the reference subframe, and the transmission unit determines that the number of the first sTTIs that can be used for signal allocation is greater than that of the reference subframe. If the first sTTI, which is a predetermined interval before the timing of receiving the upstream signal, cannot be used for signal allocation in a small number of subframes, the downstream signal is transmitted at the rearmost first sTTI that cannot be used for signal allocation. ..

In the base station of the present disclosure, the downlink signal includes uplink allocation control information indicating allocation of the uplink signal, the transmission unit sets a predetermined interval with the length of the first sTTI forming the reference subframe as a reference, and the transmission unit In a subframe in which the number of 1st sTTIs that can be used for signal allocation is less than the reference subframe, if the 1st sTTI after a predetermined interval from the timing of the 2nd sTTI that received the uplink signal cannot be used for signal allocation, The ACK/NACK signal for the upstream signal is transmitted at the first 1st sTTI after the 1st sTTI that cannot be used for allocation.

In the base station of the present disclosure, the transmitting unit and the receiving unit use the common HARQ process ID when switching from using the first sTTI and the second sTTI to using the TTI.

A terminal according to the present disclosure includes a receiving unit that receives a downlink signal by using a first sTTI (short TTI) of the downlink whose TTI length is shorter than TTI (Transmission Time Interval), and an uplink whose TTI length is shorter than TTI. When the length of the first sTTI is shorter than the second sTTI, the transmission unit uses the length of the first sTTI as a reference from the reception timing of the downlink signal. The uplink signal is transmitted at the second sTTI after a predetermined interval set as.

The communication method of the present disclosure transmits a downlink signal using the first sTTI (short TTI) of the downlink whose TTI length is shorter than the TTI (Transmission Time Interval), and transmits the downlink signal using the first sTTI (short TTI) of the downlink which is shorter than the TTI. When the upstream signal is received using 2sTTI and the length of the first sTTI is shorter than the second sTTI, the upstream signal is the first signal after a predetermined interval set based on the length of the first sTTI from the transmission timing of the downstream signal. Received in 2s TTI.

The communication method of the present disclosure receives a downlink signal using the first sTTI (short TTI) of the downlink, which has a shorter TTI length than the TTI (Transmission Time Interval), and receives the downlink signal by using the first sTTI (short TTI) of the downlink. When the upstream signal is transmitted using 2sTTI and the length of the first sTTI is shorter than the second sTTI, the upstream signal is the first after a predetermined interval set based on the length of the first sTTI from the reception timing of the downstream signal. It is transmitted with 2s TTI.

One aspect of the present disclosure is useful for mobile communication systems.

100 base station 101 sTTI determination unit 102 sPDCCH generation unit 103,209 error correction coding unit 104,210 modulation unit 105,211 signal allocation unit 106,212 transmission unit 107,201 reception unit 108,202 signal separation unit 109 ACK/NACK Reception unit 110, 203 Demodulation unit 111, 204 Error correction decoding unit 112 ACK/NACK generation unit 200 Terminal 205 sTTI setting unit 206 Error determination unit 207 ACK/NACK generation unit 208 sPDCCH reception unit

Claims (13)

A transmission unit for transmitting a downlink signal using the first sTTI (short TTI) of the downlink, which has a shorter TTI length than TTI (Transmission Time Interval),
A receiving unit for receiving an uplink signal using the second sTTI on the uplink, which has a shorter TTI length than the TTI;
Equipped with,
When the length of the first sTTI is shorter than the second sTTI, the receiving unit performs the uplink at the second sTTI after a predetermined interval set based on the length of the first sTTI from the transmission timing of the downlink signal. Receive the signal,
The downlink signal includes uplink allocation control information indicating allocation of the uplink signal,
The transmitter transmits an ACK/NACK signal for the upstream signal at the first sTTI after the predetermined interval from the timing of the second sTTI when the upstream signal is received,
Different from the first sTTI in which the uplink allocation control information is transmitted and the first sTTI in which the ACK/NACK signal is transmitted,
The transmitter transmits the ACK/NACK signal in the first sTTI one before the first sTTI in which the uplink allocation control information having the same HARQ process ID as the ACK/NACK signal is transmitted. To do
base station. The receiving unit receives the upstream signal at the first second sTTI after a predetermined number of the first sTTIs from the transmission timing of the downstream signal,
The base station according to claim 1. The reception unit delays the reception timing of the uplink signal when the same timing as the timing after the interval of the first sTTI of the predetermined number does not match the boundary of the second sTTI from the transmission timing of the downlink signal,
The base station according to claim 2. The downlink signal includes downlink allocation control information indicating allocation of downlink data signals,
The receiving unit receives an ACK/NACK signal for the downlink data signal at the second sTTI after the predetermined interval from the timing of the first sTTI that transmitted the downlink data signal,
The base station according to claim 1. The receiving unit receives the ACK/NACK signal for each of the plurality of downlink signals transmitted in the same subframe, in the plurality of second sTTIs in one subframe.
The base station according to claim 1. The receiving unit receives the uplink signal at the first second sTTI after a lapse of time obtained by adding an absolute time to a predetermined number of the first sTTI intervals from the transmission timing of the downlink signal.
The base station according to claim 1. From the transmission timing of the downlink signal, the receiving unit receives the uplink signal at the first second sTTI after a lapse of a larger time of a predetermined number of the first sTTI intervals and absolute time,
The base station according to claim 1. The transmission unit sets the predetermined interval with reference to the length of the first sTTI forming a reference subframe,
The transmitter may use the first sTTI for signal allocation in the subframe in which the number of the first sTTIs that can be used for signal allocation is smaller than the reference subframe, the predetermined interval before the timing at which the uplink signal is received. If not possible, transmit the downlink signal in the rearmost first sTTI before the first sTTI that cannot be used for allocation of the signal,
The base station according to claim 1. The downlink signal includes uplink allocation control information indicating allocation of the uplink signal,
The transmission unit sets the predetermined interval with reference to the length of the first sTTI forming a reference subframe,
In the subframe in which the number of the first sTTIs that can be used for signal allocation is smaller than the reference subframe, the transmission unit signals the first sTTI after the predetermined interval from the timing of the second sTTI that received the uplink signal. ACK/NACK signal for the upstream signal is transmitted in the first sTTI first after the first sTTI that cannot be used for allocating the signal,
The base station according to claim 1. The transmitting unit and the receiving unit use a common HARQ process ID when switching from using the first sTTI and the second sTTI to using the TTI.
The base station according to claim 1. A receiving unit for receiving a downlink signal by using a first sTTI (short TTI) on the downlink, which has a shorter TTI length than TTI (Transmission Time Interval),
A transmitter for transmitting an uplink signal using the second sTTI on the uplink, which has a shorter TTI length than the TTI,
Equipped with,
When the length of the first sTTI is shorter than the second sTTI, the transmission unit uses the second sTTI after the predetermined interval set with reference to the length of the first sTTI from the reception timing of the downlink signal. Send an upstream signal,
The downlink signal includes uplink allocation control information indicating allocation of the uplink signal,
The receiving unit receives an ACK/NACK signal for the upstream signal at the first sTTI after the predetermined interval from the timing of the second sTTI that transmitted the upstream signal,
Different from the first sTTI in which the uplink allocation control information is received and the first sTTI in which the ACK/NACK signal is received,
The receiving unit receives the ACK/NACK signal at the first sTTI immediately before the first sTTI at which the uplink allocation control information having the same HARQ process ID as the ACK/NACK signal is received. To do
Terminal. The downlink signal is transmitted using the first sTTI (short TTI) of the downlink whose TTI length is shorter than TTI (Transmission Time Interval),
Receive an uplink signal using the second sTTI on the uplink, which has a shorter TTI length than the TTI,
When the length of the first sTTI is shorter than the second sTTI, the upstream signal is received at the second sTTI after the predetermined interval set based on the length of the first sTTI from the transmission timing of the downstream signal. Is
The downlink signal includes uplink allocation control information indicating allocation of the uplink signal,
An ACK/NACK signal for the upstream signal is transmitted at the first sTTI after the predetermined interval from the timing of the second sTTI when the upstream signal is received,
Different from the first sTTI in which the uplink allocation control information is transmitted and the first sTTI in which the ACK/NACK signal is transmitted,
The ACK/NACK signal is transmitted in the first sTTI one before the first sTTI in which the uplink allocation control information having the same HARQ process ID as the HARQ process ID of the ACK/NACK signal is transmitted.
Communication method. The downlink signal is received using the first sTTI (short TTI) of the downlink, which has a shorter TTI length than the TTI (Transmission Time Interval),
The uplink signal is transmitted using the second sTTI on the uplink, which has a shorter TTI length than the TTI,
When the length of the first sTTI is shorter than the second sTTI, the upstream signal is transmitted at the second sTTI after the predetermined interval set based on the length of the first sTTI from the reception timing of the downstream signal. Is
The downlink signal includes uplink allocation control information indicating allocation of the uplink signal,
An ACK/NACK signal for the upstream signal is received at the first sTTI after the predetermined interval from the timing of the second sTTI that transmitted the upstream signal,
Different from the first sTTI in which the uplink allocation control information is received and the first sTTI in which the ACK/NACK signal is received,
The ACK/NACK signal is received at the first sTTI one before the first sTTI at which the uplink allocation control information of the same HARQ process ID as the HARQ process ID of the ACK/NACK signal is received.
Communication method.

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