KR20170113758A - Method and apparatus for scheduling in mobile communication system - Google Patents

Abstract

A base station of a mobile communication system in which one subframe is composed of two slots sets a short transmission time interval (sTTI), which is a minimum unit of scheduling for data transmission, to one slot length, Through an ePDCCH (enhanced physical downlink control channel) allocated to each slot.

Description

[0001] METHOD AND APPARATUS FOR SCHEDULING IN MOBILE COMMUNICATION SYSTEM [0002]

The present invention relates to a scheduling method and apparatus in a mobile communication system and, more particularly, to a scheduling method and apparatus for scheduling a radio frame having a TTI shorter than a transmission time interval (TTI) And more particularly, to a scheduling method and an apparatus suitable for the present invention.

The access link of the conventional mobile communication system is accompanied by a certain amount of delay. In the LTE-A (Long Term Evolution-Advanced), the one-way latency between the base station and the terminal is about 5 msec.

Of the element technologies proposed in the fifth generation mobile communication system, which is a new generation communication network, the access link requires a lower delay than the conventional access link.

In 3GPP, research is being conducted in the field of low softening with the goal of Release -14.

It is highly likely that a frame structure in which a 0.5 ms slot is set to one TTI out of the frame structure in which the conventional 1 ms is set to 1 TTI (Transmission Time Interval) in view of the present technical requirements is large.

As described above, in the case of the TTI of the slot length, a scheme different from the conventional scheduling is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a scheduling method and apparatus capable of providing scheduling suitable for a radio frame having a slotted TTI.

According to an embodiment of the present invention, a scheduling method in a base station of a mobile communication system in which one subframe is composed of two slots is provided. The scheduling method may include setting a short transmission time interval (sTTI) as a minimum unit of scheduling for data transmission to one slot length, and allocating resource allocation information for each slot in the one subframe to each slot through an enhanced physical downlink control channel (ePDCCH).

The one subframe may be divided into a control region and a data region in a time domain, and an ePDCCH allocated to each slot may be located in a partial region of the data region.

In the downlink scheduling, the ePDCCH allocated to each slot is allocated to the resource allocation information of the low-delay physical downlink shared channel (PDSCH) to which the downlink data is to be transmitted in the corresponding slot and the HARQ (Hybrid Automatic Repeat Request (PUCCH) resource allocation information to transmit a response to the uplink.

The time interval between the downlink data transmission on the low delay PDSCH and the HARQ response transmission on the low delay PUCCH may be 4 sTTI.

Each slot in the uplink subframe may include a low delay control region to which the low delay PUCCH is allocated.

In uplink scheduling, an ePDCCH allocated to each slot may include resource allocation information of a low-delay PUSCH (Physical Uplink Shared Channel) of a slot through which uplink data is to be transmitted.

The time interval between transmission of the resource allocation information through the ePDCCH and uplink data transmission through the low delay PUSCH may be 4 sTTI.

Each slot in the uplink subframe may include a low-delay data region to which the low-delay PUSCH is allocated.

The scheduling method may further include transmitting a resource location of the ePDCCH to a mobile station through upper layer signaling.

The scheduling method includes the steps of: determining a number of HARQ processes that can be simultaneously performed according to the number of slots included in an interval corresponding to a maximum value of a HARQ process time in each of a downlink and an uplink, The method comprising the steps of:

According to another embodiment of the present invention, there is provided a scheduling apparatus in a mobile communication system in which one subframe is composed of two slots. The scheduling apparatus includes a processor, and a transceiver. The processor sets a short transmission time interval (sTTI) to one slot length and performs resource allocation for data transmission in units of sTTI. The transceiver is connected to the processor to transmit and receive a radio signal.

A downlink subframe is divided into a control region and a data region in a time domain, and the processor sets an enhanced physical downlink control channel (ePDCCH) in a part of a data region in each slot of the downlink subframe, The resource allocation information for each slot can be transmitted through the transceiver through the set ePDCCH.

In the downlink scheduling, the ePDCCH allocated to each slot is allocated to the resource allocation information of the low-delay physical downlink shared channel (PDSCH) to which the downlink data is to be transmitted in the corresponding slot and the HARQ (Hybrid Automatic Repeat Request (PUCCH) resource allocation information to transmit a response to the uplink.

Each slot in the uplink subframe may include a low-delay data region to which the low-delay PUSCH is allocated.

In the uplink scheduling, the ePDCCH allocated to each slot may include low-delay Physical Uplink Shared Channel (PUSCH) resource allocation information of each slot to which uplink data is to be transmitted.

Each slot in the uplink subframe may include a low-delay data region to which the low-delay PUSCH is allocated.

According to an embodiment of the present invention, it is possible to reduce the unidirectional delay between the base station and the terminal by providing a method of controlling and setting a low-delay access link having a short TTI with a slot length.

1 is a diagram illustrating a TTI in a conventional mobile communication system.
2 is a diagram illustrating an example of an sTTI according to an embodiment of the present invention.
3 is a diagram illustrating an example of a low-delay frame structure according to an embodiment of the present invention.
4 is a diagram illustrating a downlink HARQ according to an embodiment of the present invention.
5 is a diagram illustrating the maximum number of downlink HARQ processes according to an embodiment of the present invention.
6 is a diagram illustrating uplink scheduling according to an embodiment of the present invention.
7 is a diagram illustrating the number of HARQ processes in uplink scheduling according to an embodiment of the present invention.
8 is a diagram illustrating a method of setting an ePDCCH resource according to an embodiment of the present invention.
9 is a diagram illustrating a scheduling apparatus according to an embodiment of the present invention.

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

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

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

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

Now, a scheduling method and apparatus in a mobile communication system according to an embodiment of the present invention will be described in detail with reference to the drawings.

1 is a diagram showing a TTI in a conventional LTE system.

Referring to FIG. 1, in an LTE system which is a typical mobile communication system, one radio frame includes 10 subframes (# 0 to # 9) having a length of 10 ms in the time domain and having a length of 1 ms .

Each of the subframes # 0 to # 9 is composed of two slots # S0 and # S1, and each of the slots # S0 and # S1 has a length of 0.5 ms. The slots # S0 and # S1 include a plurality of symbols in the time domain and a plurality of resource blocks (RB) in the frequency domain. The RB includes a plurality of subcarriers in the frequency domain. Symbol may be referred to as an Orthogonal Frequency Division Multiplex (OFDM) symbol, an Orthogonal Frequency-Division Multiple Access (OFDMA) symbol, or a Single Carrier Frequency Division Multiple Access (SC-FDMA) symbol according to a multiple access scheme. The number of symbols included in one slot can be variously changed according to the channel bandwidth or the length of the CP. For example, in the case of a normal CP, one slot includes seven symbols, while in the case of an extended CP, one slot includes six symbols.

The DL subframe may be divided into a control region and a data region in a time domain. A Physical Downlink Control Channel (PDCCH), a Physical Control Format Indicator Channel (PCFICH), a Physical Hybrid Automatic Repeat Request Indicator Channel (PHICH), and the like may be allocated to the control region. The PDCCH transmits downlink control information (DCI). The DCI includes downlink scheduling information including resource allocation information of the PDSCH and control information for indicating uplink scheduling information including PUSCH (Physical Uplink Shared Channel) resource allocation information. A maximum of 3 (or 4) symbols located in the first part in the first slot # S0 of the DL subframe correspond to the control area, and the remaining symbols correspond to the data area. A data downlink shared channel (PDSCH) for transmitting downlink data is allocated to the data area. Also, an enhanced physical downlink control channel (ePDCCH) may be allocated to the data area. The ePDCCH transmits additional control information. The resource used for ePDCCH transmission can be used only for a plurality of predefined subframes and a plurality of predefined RBs through upper layer signaling (for example, RRC (Radio Resource Control)) for each UE.

The UL subframe may be divided into a control region and a data region in the frequency domain. A PUCCH (Physical Uplink Control Channel) for transmitting uplink control information (UCI) is allocated to the control region. The data area is assigned a PUSCH for transmitting uplink data.

In the LTE system, a transmission time interval (TTI) is used as a minimum time unit for transmitting data, and is set equal to one subframe length. That is, the TTI has a time length of 1 ms and can be a minimum unit of scheduling for data transmission. Therefore, PDSCH or PUSCH allocation is performed in units of TTI.

In the LTE system in which the scheduling is performed in units of TTI, the HARQ RTT (Hybrid Automatic Repeat Request Round Trip Time) is 8 TTI.

For example, the uplink HARQ procedure is performed as follows.

The UE receives the uplink scheduling information by the PDCCH in the n < th > subframe from the Node B.

The UE transmits uplink data, i.e., an uplink transmission block, through the PUSCH using uplink scheduling information in an (n + 4) th subframe.

The base station transmits an HARQ response to the uplink data through the PHICH in the (n + 8) th subframe. At this time, the UE receiving the negative response in the HARQ response retransmits the uplink data through the PUSCH in the (n + 12) th subframe.

The base station transmits an HARQ response to the uplink data through the PHICH in the (n + 16) th subframe.

As described above, in the LTE system, the transmission interval of the UL scheduling, the UL data transmission, the HARQ response, and the UL data retransmission is set to 4 TTIs. Therefore, since the UE retransmits in the (n + 12) th subframe after the initial transmission in the (n + 4) th subframe, the HARQ is performed with the 8 subframes as the HARQ period.

According to the embodiment of the present invention, a TTI having a length shorter than 1 ms (hereinafter referred to as "sTTI (short TTI)") is used in order to reduce the end-to-end unidirectional transmission delay.

2 is a diagram illustrating an example of an sTTI according to an embodiment of the present invention.

Referring to FIG. 2, one radio frame includes 10 subframes (# 0 to # 9) having a length of 10 ms in the time domain and a length of 1 ms. Each of the subframes # 0 to # 9 is composed of two slots # S0 and # S1, and each of the slots # S0 and # S1 has a length of 0.5 ms. In this case, in the conventional LTE system, a TTI having one subframe length is used as a scheduling unit, whereas a sTTI having one slot length is used as a scheduling unit according to an embodiment of the present invention.

As described above, when the sTTI is set to one slot length, a transmission delay gain can be obtained as compared with a TTI having a length of 1 ms, and the frame, subframe, and symbols of the LTE system can be used without modification.

Hereinafter, a frame having sTTI is referred to as a low-delay frame, and a system having a low-delay frame structure is referred to as a low-delay system.

3 is a diagram illustrating an example of a low-delay frame structure according to an embodiment of the present invention.

3, the low-delay system includes a low-delay PDCCH (hereinafter referred to as sPDCCH) having the same function as the PDCCH, PDSCH, PUCCH and PUSCH of the existing LTE system, a low-delay PDSCH (Short-TTI PUCCH) and a Short-TTI PUSCH (hereinafter, referred to as Short-TTI PUCCH). In addition, the low-delay system can be defined by using a low-delay channel corresponding to a channel (for example, PHICH) used in the existing LTE system.

In the downlink sub-frame having the sTTI, an ePDCCH area to which an ePDCCH is allocated is located in a part of the data area. The ePDCCH transmits the sPDSCH resource allocation and the sPUSCH resource allocation information. That is, the ePDCCH region becomes the low-delay control region, and the ePDCCH performs the sPDCCH function.

At this time, sPDCCH, sPDSCH, sPUCCH, and sPUSCH are scheduled in units of sTTI, so the ePDCCH region can be located in each slot (# S0, # S1). In addition, a low-delay data area in which the sPDSCH is allocated to another part of the data area is located, and a low-delay data area can also be located in each of the slots #S0 and # S1.

That is, the ePDCCH located in the slot (# S0) transmits the sPDSCH located in the slot (# S0) and the sPUSCH resource allocation information for transmitting the response to the downlink data transmitted through the sPDSCH, The ePDCCH located in the slot # 1 transmits the sPDSCH located in the slot # S1 and the sPUSCH resource allocation information for transmitting the response to the downlink data transmitted through the sPDSCH. At this time, the sPDSCH indicated by the ePDCCH may be located in the same downlink subframe as the ePDCCH, or may be located in the downlink subframe of the carrier different from the ePDCCH when supporting the multicarrier.

As described above, since the ePDCCH can be set for each UE through upper layer signaling, ePDCCH resources can be set for each UE starting the low-delay service.

In the uplink sub-frame having the sTTI, for the sPUCCH and the sPUSCH allocated in units of sTTI, a part of the data region in the frequency domain can be used as the low-delay control region and the low-delay data region. The sPUCCH is allocated in the low delay control area, and the sPUSCH is allocated in the low delay data area. And the PUSCH may be allocated to the remaining part of the data area in the frequency domain.

Since the low delay system can use the frame structure of the LTE system as it is, it can provide services not only to LTE terminals operating in units of TTI but also to low-delay terminals operating in units of sTTI.

FIG. 4 is a diagram illustrating a downlink HARQ according to an embodiment of the present invention, and FIG. 5 is a diagram illustrating the maximum number of downlink HARQ processes according to an embodiment of the present invention.

Referring to FIG. 4, the base station transmits downlink scheduling information 410 and 420 through ePDCCH in slots #S0 and # S1 of the n-th subframe, slots #S0 and # S1) transmits the downlink data through the sPDSCH indicated by the downlink scheduling information.

The UE transmits HARQ responses 430 and 440 for the downlink data through the sPUCCH in the slots #S0 and # S1 of the (n + 2) th subframe.

ACK and NACK signals are included in the HARQ response. If the downlink data is successfully decoded, the ACK signal is transmitted. If the downlink data is unsuccessfully decoded, the NACK signal is transmitted.

The base station receiving the NACK signal transmits downlink scheduling information 450 and 460 for retransmission on the ePDCCH in slots #S0 and # S1 of the (n + 4) th subframe, The downlink data is transmitted through the sPDSCH indicated by the downlink scheduling information in each of the slots (# S0, # S1) of the # 1 subframe.

In the LTE system, the transmission interval of the uplink scheduling, the uplink data transmission, the HARQ response and the uplink data retransmission is set to 4 TTI. However, according to the downlink scheduling in units of sTTI according to the embodiment of the present invention, The transmission interval of link scheduling (downlink data transmission), HARQ response, and downlink scheduling (retransmission) for retransmission can be set to 4 sTTI. Therefore, the base station performs retransmission in the (n + 4) th subframe after 8 sTTI after the initial transmission in the slot # S0 of the nth subframe. Therefore, since the HARQ RTT becomes 4 TTI, the transmission delay can be reduced compared to the conventional scheduling in units of TTI.

Meanwhile, the number of HARQ processes that can be simultaneously performed in the downlink scheduling is determined according to the number of slots included in the interval corresponding to the maximum value of the HARQ process time in the downlink.

For example, in the downlink scheduling shown in FIG. 4, the HARQ RTT is 4 TTIs and 8 slots are included in 4 TTIs. Therefore, the number of HARQ processes that can be performed simultaneously can be determined to be eight.

As shown in FIG. 5, eight independent HARQ processes (Process 0 to Process 7) can be performed simultaneously.

FIG. 6 is a diagram illustrating uplink scheduling according to an embodiment of the present invention, and FIG. 7 is a diagram illustrating the number of HARQ processes in uplink scheduling according to an embodiment of the present invention. Referring to FIG.

Referring to FIG. 6, the base station transmits uplink scheduling information 610 and 620 through ePDCCH in slots #S0 and # S1 of the n-th subframe.

The UE transmits the uplink data 630 and 640 through the sPUSCH indicated by the uplink scheduling information in the slots #S0 and # S1 of the (n + 2) th subframe.

The base station transmits an HARQ response for the uplink data through the sPHICH in each of the slots #S0 and # S1 of the (n + 4) th subframe, and transmits uplink scheduling information 650 for uplink data retransmission through the ePDCCH , 660).

At this time, the UE receiving the NACK signal from the base station retransmits the uplink data through the sPUSCH indicated by the uplink scheduling information in each of the slots #S0 and # S1 of the (n + 6) th subframe.

In this manner, the transmission interval of the uplink scheduling, the uplink data transmission, the HARQ response, and the uplink data retransmission is set to 4 sTTI in the uplink HARQ according to the uplink scheduling in units of sTTI. Accordingly, the UE can perform retransmission in the (n + 6) th subframe after 8 sTTI after the initial transmission in the (n + 2) th subframe. Therefore, since the HARQ RTT becomes 4 TTI, the transmission delay can be reduced compared to the conventional scheduling in units of TTI.

Also, the number of HARQ processes that can be performed simultaneously is determined according to the number of slots included in the interval corresponding to the maximum value of the HARQ process time in the uplink.

For example, in the case of the UL scheduling shown in FIG. 6, HARQ RTT is 4 TTIs and 8 slots are included in 4 TTIs. Therefore, the number of HARQ processes that can be performed simultaneously can be determined to be eight.

As shown in FIG. 7, eight independent HARQ processes (Process 0 to Process 7) can be performed simultaneously.

8 is a diagram illustrating a method of setting an ePDCCH resource according to an embodiment of the present invention.

Referring to FIG. 8, the UE transmits a low-latency service request to a PDN (Packet Data Network) (S810).

The PDN receiving the low-delay service request transmits a low-delay session start request for the low-delay service to the EPC node, for example, SGW, PGW, MME (Mobility Management Entity), and the EPC node transmits the low- (S820).

The base station transmits ePDCCH setup information for the UE to the UE, and the UE receives the ePDCCH setup information and performs a low delay bearer setup between the BS and the UE (S830). The UE can perform ePDCCH monitoring based on the ePDCCH setting information.

In step S840, the base station transmits a low-delay session completion response to the EPC node and the EPC node transmits a low-delay session setup response to the PDN in step S840.

The PDN transmits a low-delay service response to the terminal (S850).

Thereafter, the PDN starts transmission of low-latency data to the terminal (S860).

9 is a diagram illustrating a scheduling apparatus according to an embodiment of the present invention.

9, the scheduling apparatus 900 includes a processor 910, a transceiver 920, and a memory 930. [

The processor 910 sets one slot length to sTTI as described above, and performs downlink and uplink scheduling in units of sTTI. To this end, the processor 910 instructs the corresponding UE to set up an ePDCCH resource through upper layer signaling, generates downlink and uplink scheduling information for each slot, and transmits the downlink and uplink scheduling information through the ePDCCH of each slot.

The transceiver 920 is coupled to the processor 910 to transmit and receive wireless signals.

The memory 930 stores instructions for executing in the processor 910 or temporarily stores the instructions loaded from a storage device (not shown), and the processor 910 is stored in the memory 930 Execute the loaded command.

The processor 910 and the memory 930 are connected to each other via a bus (not shown), and an input / output interface (not shown) may be connected to the bus. At this time, a transceiver 920 is connected to the input / output interface, and peripheral devices such as an input device, a display, a speaker, and a storage device may be connected.

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

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

Claims (16)

A scheduling method in a base station of a mobile communication system in which one subframe is composed of two slots,
Setting a short transmission time interval (sTTI) as a minimum unit of scheduling for data transmission to one slot length, and
Transmitting resource allocation information for each slot in the one subframe through an enhanced physical downlink control channel (ePDCCH) assigned to each slot
/ RTI > The method of claim 1,
Wherein the one subframe is divided into a control region and a data region in a time domain,
Wherein the ePDCCH allocated to each slot is located in a partial area of the data area. The method of claim 1,
In the downlink scheduling, the ePDCCH allocated to each slot is allocated to the resource allocation information of the low-delay physical downlink shared channel (PDSCH) to which the downlink data is to be transmitted in the corresponding slot and the HARQ (Hybrid Automatic Repeat Request ) ≪ / RTI > response to a physical uplink control channel (PUCCH) resource allocation information. 4. The method of claim 3,
Wherein the time interval between the downlink data transmission on the low delay PDSCH and the HARQ response transmission on the low delay PUCCH is 4 sTTI. 4. The method of claim 3,
And each slot in the uplink subframe includes a low-delay control region to which the low-delay PUCCH is allocated. The method of claim 1,
Wherein in the uplink scheduling, the ePDCCH allocated to each slot includes resource allocation information of a low-delay PUSCH (Physical Uplink Shared Channel) of a slot through which uplink data is to be transmitted. The method of claim 6,
Wherein the time interval between the resource allocation information transmission through the ePDCCH and the uplink data transmission through the low delay PUSCH is 4 sTTI. 8. The method of claim 7,
And each slot in the uplink subframe includes a low-delay data region to which the low-delay PUSCH is allocated. The method of claim 1,
Transmitting a resource location of the ePDCCH to a terminal through higher layer signaling
≪ / RTI > The method of claim 1,
Determining a number of HARQ processes that can be performed simultaneously according to the number of slots included in the interval corresponding to the maximum value of the HARQ process time in each of the downlink and the uplink,
Scheduling to perform a determined number of HARQ processes
≪ / RTI > 1. A scheduling apparatus in a mobile communication system in which one subframe is composed of two slots,
a processor that sets a short transmission time interval (sTTI) to one slot length and performs resource allocation for data transmission in units of sTTI, and
A transceiver coupled to the processor for transmitting and receiving wireless signals,
. 12. The method of claim 11,
The DL subframe is divided into a control region and a data region in a time domain,
The processor sets an enhanced physical downlink control channel (ePDCCH) in a part of the data area in each slot of the downlink subframe and transmits resource allocation information for each slot through the ePDCCH set in each slot through a transceiver Scheduling device. 12. The method of claim 11,
In the downlink scheduling, the ePDCCH allocated to each slot is allocated to the resource allocation information of the low-delay physical downlink shared channel (PDSCH) to which the downlink data is to be transmitted in the corresponding slot and the HARQ (Hybrid Automatic Repeat Request ) ≪ / RTI > response to a physical uplink control channel (PUCCH) resource allocation information. The method of claim 13,
Wherein each slot in the uplink subframe includes a low-delay data region to which the low-delay PUSCH is to be allocated. The method of claim 12,
In the uplink scheduling, the ePDCCH allocated to each slot includes low-delay Physical Uplink Shared Channel (PUSCH) resource allocation information of each slot to which uplink data is to be transmitted. 16. The method of claim 15,
Wherein each slot in the uplink subframe includes a low-delay data region to which the low-delay PUSCH is to be allocated.

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