KR102216731B1 - Method of scheduling for control information in mobile communication system and method of receiving the scheduled control information - Google Patents

Abstract

Disclosed are a method for scheduling control information and a method for receiving scheduled control information in a mobile communication system. The base station simultaneously performs scheduling for the n-th transmission unit time interval in a first transmission unit time (TTI) consecutive in time and transmits scheduling information to at least one terminal. Accordingly, it is possible to reduce the power consumption of the terminal and increase the capacity of the system.

Description

How to schedule control information in a mobile communication system and how to receive scheduled control information {METHOD OF SCHEDULING FOR CONTROL INFORMATION IN MOBILE COMMUNICATION SYSTEM AND METHOD OF RECEIVING THE SCHEDULED CONTROL INFORMATION}

The present invention relates to mobile communication technology, and more particularly, to a method for scheduling control information for data transmission in a mobile communication system and a method for receiving scheduled control information.

Mobile communication systems such as 3GPP (3rd Generation Partnership Project) series LTE (Long Term Evolution) and LTE-A (LTE-Advanced) allow various data such as video and wireless data to be transmitted at a speed comparable to a wired communication network. Standardization of technology is in progress.

In the LTE or LTE-A system, time-frequency resources are assigned a control channel (e.g., PDCCH (Physical Downlink Control Channel)) and a data channel (e.g., PDSCH (Physical Downlink Shared Channel)). It can be divided into a data area.

Data may be delivered through a data region excluding a control region in a time-frequency resource.

Meanwhile, in the LTE or LTE-A system, the terminal performs blind decoding on the PDCCH at every transmission time interval (TTI), and whether the base station transmits downlink data to the terminal at a corresponding time, and the base station It is checked whether or not resources for uplink data transmission have been allocated to this terminal. According to the current LTE standard, the terminal is defined to perform blind decoding on the PDCCH up to 44 times.

When transmitting control information for each transmission unit time (TTI), the base station transmits only control information corresponding to each transmission unit time. Accordingly, the terminal performs blind decoding on the PDCCH even when there is no control information corresponding to it at every transmission unit time, and thus power consumption of the terminal using the battery as an energy source increases.

In addition, as described above, since the base station transmits only control information corresponding to each transmission unit time, the PDCCH symbol for transmission of control information occupies a significant portion, and thus, the resource area for transmitting data is reduced. There is a disadvantage of reducing the overall capacity.

An object of the present invention for solving the above-described problem is to provide a control information scheduling method capable of reducing the number of times the terminal performs blind decoding and increasing the capacity of the system.

In addition, another object of the present invention is to provide a method for a terminal to receive control information scheduled as described above.

The control information scheduling method according to an aspect of the present invention for achieving the object of the present invention described above is a scheduling method performed in a base station, and is transmitted in a first transmission time interval (TTI) that is consecutive in time. And simultaneously performing scheduling for a unit time period (where n is a natural number of two or more) and transmitting the scheduling information to at least one terminal.

Here, the performing of the scheduling may schedule downlink data for at least one terminal in the same resource region among resource regions to which downlink data is mapped in each transmission unit time.

Here, the performing of the scheduling may include information on the number of simultaneously scheduled transmission unit times in control information mapped to a specific region among resource regions to which control information is mapped in the first transmission unit time.

Here, the performing of the scheduling includes control information mapped to a specific region among resource regions to which control information is mapped in the first transmission unit time, and control to be decoded by the terminal in each of the second to n-th transmission unit times. Location information of the resource to which the information is mapped may be included.

Here, the control information to be decoded by the terminal in each of the second to n-th transmission unit times includes information dynamically changed from the control information scheduled in the first transmission unit time.

Here, the dynamically changed information may include at least one of information on a hybrid automatic repeat request (HARQ) process index, a new data indicator (NDI), and redundancy version (RV) information.

Here, in the performing of the scheduling, when the resource region to which the control information to be decoded by the terminal is mapped in the second to nth transmission unit time is fixed, the terminal decodes by using a common search space. You can schedule control information to do.

Here, in the performing of the scheduling, resources scheduled for the first terminal in the n-th transmission unit time interval in the first transmission unit time may be simultaneously scheduled for the second terminal.

In addition, a method for receiving control information of a terminal according to an aspect of the present invention for achieving another object of the present invention is for consecutive first transmission unit intervals to nth transmission unit intervals (where n is a natural number of 2 or more). A method of receiving simultaneously scheduled control information by a terminal, wherein blind decoding is performed on a resource region to which control information is mapped in the first transmission unit interval to confirm first control information, and based on the checked control information And checking second control information by performing decoding on a resource at a location indicated by the control information among resource regions included in the second to nth transmission unit intervals.

Here, the first control information includes at least one of information on the number of transmission unit times scheduled at the same time and location information to which the second control information to be decoded by the terminal in each of the second to nth transmission unit times is mapped. Can include.

Here, the second control information may include information dynamically changed from the first control information.

Herein, the method of receiving control information of the terminal includes: after the terminal confirms the second control information, applying the second control information to the first control information to reflect information dynamically changed from the first control information It may further include.

Here, the second control information may include at least one of information on a hybrid automatic repeat request (HARQ) process index, a new data indicator (NDI), and redundancy version (RV) information.

In this case, the step of checking the second control information includes, as a result of the UE decoding a resource at a location indicated by the second control information in a predetermined transmission unit interval among the second to nth transmission unit intervals, the When there is no control information allocated to the terminal, it may be determined that resources are allocated to other terminals in the predetermined transmission unit period.

Here, the method for receiving control information of the terminal may further include receiving downlink data in each transmission unit section based on the first control information and the second control information.

According to the method for scheduling control information and the method for receiving scheduled control information in the mobile communication system as described above, the same resources are all scheduled so that the base station can transmit data to at least one terminal for a plurality of transmission unit times (TTIs). The signal is transmitted through multi-TTI scheduling.

The UE performs PDCCH blind decoding in the first TTI of the multi-TTI scheduling period, and information on the number of multi-TTI scheduled TTIs (or information on the multi-TTI scheduled period) and control channel elements to be decoded in the TTI after the first TTI (CCE: Control Channel Element) After obtaining location information, in a subsequent TTI, PDCCH decoding is performed at a corresponding CCE location to receive data transmitted to itself.

Accordingly, the number of blind decoding of the terminal can be minimized, and power consumption of the terminal can be reduced through this.

In addition, by scheduling a plurality of TTIs at once, the amount of control information transmitted for each TTI can be reduced, and through this, a PDCCH symbol for transmission of control information can be reduced. In addition, as the number of PDCCH symbols for transmission of control information decreases, data can be additionally transmitted as much as the reduced PDCCH symbol, thereby increasing system capacity.

1 shows a mobile communication system to which a method for scheduling control information and a method for receiving scheduled control information according to an embodiment of the present invention is applied.
2 is a flowchart illustrating a method of scheduling a base station according to an embodiment of the present invention.
3 is a conceptual diagram illustrating a scheduling method according to an embodiment of the present invention.
4 is a flowchart illustrating a method of operating a terminal according to an embodiment of the present invention.

In the present invention, various modifications may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail.

However, this is not intended to limit the present invention to a specific embodiment, it is to be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in the present application. Does not.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. In describing the present invention, in order to facilitate an overall understanding, the same reference numerals are used for the same elements in the drawings, and duplicate descriptions for the same elements are omitted.

The scheduling method according to the present invention provides a multi-transmission unit time (Multi-TTI) scheduling method in which a base station schedules a terminal to transmit data using the same resource during a plurality of transmission time intervals (TTIs). do.

1 illustrates a mobile communication system to which a method for scheduling control information and a method for receiving scheduled control information according to embodiments of the present invention is applied.

Referring to FIG. 1, a mobile communication system is arranged to provide various communication services such as voice and packet data.

The mobile communication system includes a terminal 10 and a base station 20 performing uplink and downlink communication with the terminal 10 and the terminal 10. In the present specification, the terminal 10 or UE (User Equipment) is a generic concept that means a user terminal in wireless communication, as well as a UE in WCDMA, LTE, HSPA, etc., as well as a mobile station (MS) and a user equipment (UT) in GSM. Terminal), SS (Subscriber Station), wireless device (wireless device) should be interpreted as a concept including all.

The base station 20 generally refers to a station communicating with the terminal 10, and a base station, a node-B (Node-B), an evolved node-B (eNB), a base transceiver system (BTS), an access point ( Access Point), relay node, RRH (Remote Radio Head), RU (Radio Unit), etc. may be referred to as other terms.

In addition, in the present specification, the base station 20 should be interpreted in a comprehensive meaning indicating a partial area covered by a base station controller (BSC) in CDMA and a NodeB in WCDMA, and a radio remote head (RRH) connected to the base station, and a relay. It is used as a comprehensive concept that refers to all types of devices that can communicate with one terminal such as a relay node, a sector of a macro cell, a site, and other femtocells, pico cells, and micro cells. .

In the present specification, the terminal 10 and the base station 20 are transmission/reception subjects used to implement the technology or technical idea described herein, and are used in a comprehensive sense, and are not limited to terms or words specifically referred to.

In FIG. 1, two terminals 10 and one base station 20 are shown, but the present invention is not limited thereto. That is, it is possible for one or a plurality of base stations 20 to communicate with a plurality of terminals 10, and it is possible for one terminal 10 to communicate with a plurality of base stations 20.

There is no limitation on the multiple access technique applied to the communication system, and the present invention provides a code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), and OFDM. -It can be applied to various multiple access techniques such as FDMA, OFDM-TDMA, OFDM-CDMA.

In addition, the present invention is a TDD (Time Division Duplex) scheme in which uplink transmission and downlink transmission are transmitted using different times, a frequency division duplex (FDD) scheme transmitted using different frequencies, and a combination of TDD and FDD. It can be applied to hybrid duplexing method.

The present invention should not be construed as being limited or limited to a specific wireless communication field, but should be construed as including all technical fields to which the spirit of the present invention may be applied.

In Figure 1, the terminal 10 and the base station 20 may perform uplink and downlink communication. The base station 20 performs downlink transmission to the terminal 10. The base station 20 may transmit a physical downlink shared channel (PDSCH), which is a main physical channel for unicast transmission. In addition, the base station 20 approves scheduling for transmission in downlink control information such as scheduling required for reception of the PDSCH and an uplink data channel (for example, a physical uplink shared channel (PUSCH)). A control channel such as a physical downlink control channel (PDCCH) or an enhanced physical downlink control channel (Enhanced PDCCH, EPDCCH) for transmitting information may be transmitted. In the present specification, transmission and reception of signals through each channel may be expressed in a form in which the corresponding channel is transmitted and received.

2 is a flowchart illustrating a method of scheduling a base station according to an embodiment of the present invention.

Referring to FIG. 2, the scheduling method of the base station includes simultaneously scheduling the same resource for a plurality of consecutive transmission unit times for at least one terminal (S210) and transmitting scheduling information to at least one corresponding terminal. It may include step S220.

Hereinafter, for convenience of description, simultaneous scheduling of the same resource for a plurality of consecutive transmission unit times is referred to as multi-TTI scheduling.

In the step of performing the scheduling, the base station uses the information element of the downlink control information (DCI) of the PDCCH to be transmitted, from the start TTI at which multi-TTI scheduling starts, for several TTIs consecutively for the same resource. Multi-TTI scheduling number information indicating whether the corresponding scheduling information is valid, and control channel element (CCE) location information of the PDCCH region in which DCI is to be transmitted during the TTI after the start TTI in the multi-TTI scheduling interval. Include.

The information on the number of multi-TTI scheduling intervals may be composed of bits corresponding to the multi-TTI length and included in the DCI, and position information of the CCE may also be composed of bits and included in the DCI. Here, during a TTI after the start TTI, a common search space may be used for a CCE position to be fixedly decoded by the UE among the PDCCH regions in which DCI is to be transmitted.

The CCE of the PDCCH region to which the DCI is to be transmitted during the TTI after the start TTI may contain information elements that dynamically change during the TTI after the start TTI, and the base station maps the DCI including the dynamic change information to the corresponding CCE position of each TTI can do. Here, the information elements that can be dynamically changed include information such as a hybrid automatic repeat request (HARQ) process index, a new data indicator (NDI), and a redundancy version (RV). In addition, such information elements may be composed of information bits that are considerably smaller than existing DCI control information bits.

The terminal acquires multi-TTI scheduling information based on the control information included in the start TTI, and transmits/receives data based on the obtained information.

For example, assume that the base station allocates the same resource to one terminal for 6 TTIs including the start TTI.

The UE decodes the PDCCH at the start TTI at which multi-TTI scheduling starts, and recognizes that the same resource has been scheduled to itself for five TTIs after the start TTI. Here, in 5 TTIs after the start TTI, the UE performs PDCCH decoding only on the CCE position included in the initially received PDCCH DCI control information in order to check the dynamically changed information element among the DCI information elements.

Meanwhile, in the step of performing the scheduling, the base station may allocate the scheduled resources to other terminals even when multi-TTI scheduling is performed to one specific terminal. In this case, the base station may not transmit the DCI to the specific terminal, but may transmit the DCI to the other terminal allocated the corresponding resource. In this case, the UE scheduled in the multi-TTI scheme may perform PDCCH decoding once and confirm that there is no DCI control information transmitted to the UE in the resource region allocated to the other UE. Another new terminal that has been assigned the corresponding resource can check the DCI control information transmitted to it through PDCCH blind decoding and use the corresponding resource.

3 is a conceptual diagram illustrating a scheduling method according to an embodiment of the present invention.

3 is an illustration of time-frequency resources when multi-TTI scheduling is performed on downlink resources, and six consecutive TTIs from the first TTI (TTI#1) to the sixth TTI (TTI#6) A case in which multi-TTI scheduling is performed is illustrated.

Referring to FIG. 3, each TTI largely includes a resource region to which a PDCCH is mapped and a resource region to which a PDSCH is mapped. Hereinafter, the resource region to which the PDCCH is mapped in each TTI is referred to as a PDCCH region, and the resource region to which the PDSCH is mapped is referred to as a PDSCH region.

According to the LTE or LTE-A standard, in each TTI, the PDCCH region may consist of up to 4 symbols, and the remaining symbols may be used as the PDSCH region, but in FIG. 3, symbols are not separately classified for convenience of description.

As illustrated in FIG. 3, the base station schedules DCI for the first terminal in a specific region 310 of the PDCCH region in the first TTI (TTI#1), and in the specific resource region 321 to 325 of the PDSCH region. A resource region allocated to the first terminal in the first TTI (TTI#1) among the PDSCH regions of the second TTI (TTI#2) to the sixth TTI (TTI#6) while scheduling downlink data for the first terminal ( Downlink data may be mapped to resource regions 322 to 325 at the same location as 321. That is, the base station can schedule downlink data for the first terminal in the same PDSCH region in 6 consecutive TTIs.

Here, the base station maps the DCI for the PDCCH blind decoding of the first terminal to the PDCCH region 310 of the first TTI (TTI#1). Here, in the DCI, multi-TTI scheduling number information indicating how many TTIs the same resource is scheduled after the first TTI, and a CCE position to decode the PDCCH among subsequent TTIs (i.e., second to sixth TTIs) ( That is, 311~315) information is included. In addition, the base station schedules DCI for the first terminal in the corresponding PDCCH region of the second to sixth TTI indicated by the CCE location information. Here, the DCI information scheduled in the second to sixth TTI may include dynamically changed information elements such as HARQ Process Index, NDI, and RV.

Meanwhile, the first terminal checks the DCI scheduled in the PDCCH region 310 through blind decoding of the PDCCH in the first TTI (TTI#1). The first terminal receives data scheduled and transmitted to itself in a specific PDSCH region 321 through DCI confirmation. In addition, the first terminal checks the multi-TTI scheduling number information included in the DCI information checked in the first TTI (TTI#1), checks for how many TTIs the same resource has been scheduled, and decodes the PDCCH in a subsequent TTI. Check the CCE location.

The first terminal performs PDCCH decoding on the corresponding CCE location 311 of the second TTI (TTI#2) based on the CCE location information obtained as described above, and checks the DCI information scheduled to and transmitted to itself. And, based on the checked DCI information, downlink data scheduled and transmitted in the corresponding region 322 of the PDSCH region of the second TTI (TTI#2) is received. Here, the DCI information scheduled in the second TTI (TTI#2) may include only the contents changed from the DCI information received by the terminal in the first TTI (TTI#1), and accordingly, the second TTI (TTI#2) The resources allocated to the DCI in may be smaller than the resources allocated to the DCI in the first TTI (TTI#1).

The first terminal may receive downlink data by performing the same operation as described above in the third TTI (TTI#3) and the fourth TTI (TTI#4).

Meanwhile, in the fifth TTI (TTI#5), the first terminal performs PDCCH decoding on the corresponding CCE location 314, and as a result, the DCI 314 scheduled for itself in the fifth TTI (TTI#5) is Recognize nothing. In this case, the first terminal may determine that the base station has allocated the PDSCH resource to another terminal (eg, the second terminal).

The second terminal checks the DCI scheduled and transmitted to itself in the specific PDCCH region 330 through blind decoding of the PDCCH in the fifth TTI (TTI#5), and based on the confirmed DCI, the fifth TTI (TTI#5) In the corresponding PDSCH region 341 of, it receives data scheduled and transmitted to itself. Here, the PDSCH region 341 may overlap with the PDSCH region allocated to the first terminal.

In the sixth TTI, the first terminal receives downlink data by performing the same operation as in the aforementioned second TTI (TTI#2).

3 illustrates a case in which multi-TTI scheduling is performed for six consecutive TTIs (TTI#1 to TTI#6), but the number of TTIs to perform multi-TTI scheduling is 6 as shown in FIG. It is not limited to dogs, and there is no particular limitation on the number of TTIs. For example, the base station may dynamically determine the number of TTIs to perform multi-TTI scheduling based on the amount of data to be transmitted to the terminal, a service type, or a quality of service class.

4 is a flowchart illustrating a method of operating a terminal according to an embodiment of the present invention.

In FIG. 4, as described with reference to FIGS. 2 and 3, assuming that the base station transmits a signal by performing multi-TTI scheduling, a process of processing a signal received by the terminal is illustrated.

Referring to FIG. 4, first, when a UE receives a multi-TTI scheduled signal, it performs blind decoding of a PDCCH in a first TTI among the multi-TTIs to check the DCI scheduled for itself (S401).

Thereafter, the UE checks information on the number of multi-TTI-scheduled TTIs from the identified DCI and CCE location information to which a DCI to be decoded in subsequent TTIs is mapped (S401). In addition, the UE receives data from a corresponding PDSCH region scheduled to itself in the first TTI through the identified DCI.

The UE checks DCI by performing PDCCH decoding on the corresponding CCE location among the PDCCH regions of the next TTI based on the CCE location information acquired in the first section (S403). Here, the DCI may include information changed in the DCI identified in the first TTI, and may include information such as HARQ process index, NDI, RV, and the like. The terminal may obtain changed control information by applying the DCI changed in the current TTI interval to the DCI checked in the first TTI.

In addition, the terminal determines whether there is a DCI scheduled for itself in the current TTI based on the checked DCI (S404).

If there is a DCI allocated to the terminal in the current TTI, the terminal receives downlink data scheduled in the corresponding PDSCH region based on the DCI (S405).

Alternatively, if the terminal determines that there is no DCI scheduled to it in the current TTI, it determines that the corresponding PDSCH region is allocated to another terminal (S406).

Thereafter, the terminal determines whether the current TTI is the last TTI in the multi-TTI scheduling interval based on the information obtained in step S402, and if it is not the last TTI, repeats the steps from step S403 to the subsequent steps.

Although described with reference to the above embodiments, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention described in the following claims. I will be able to.

10: terminal
20: base station
310: PDCCH area
311, 312, 313, 314, 315: CCE location
321 322, 323, 324, 325: PDSCH region
330: PDCCH area
341: PDSCH region

Claims (15)

As a scheduling method performed in a base station,
Simultaneously performing scheduling for an n-th transmission unit time (where n is a natural number of 2 or more) in a first transmission time interval (TTI) consecutive in time; And
And transmitting the scheduling information to at least one terminal,
The step of performing the scheduling,
The location information of the resource to which the control information to be decoded by the terminal in each of the second to nth transmission unit times is mapped to control information mapped to a specific region among resource regions to which control information is mapped in the first transmission unit time. Scheduling method comprising the. In claim 1,
The performing of the scheduling comprises scheduling downlink data for at least one terminal in the same resource region among resource regions to which the downlink data is mapped in each transmission unit time. In claim 1,
The step of performing the scheduling,
And in the control information mapped to a specific region among resource regions to which control information is mapped in the first transmission unit time, information on the number of simultaneously scheduled transmission unit times is included. delete In claim 1,
The control information to be decoded by the terminal in each of the second to n-th transmission unit times includes information dynamically changed from control information scheduled in the first transmission unit time. In claim 5,
The dynamically changed information includes at least one of information on a hybrid automatic repeat request (HARQ) process index, a new data indicator (NDI), and a redundancy version (RV) information. Way. In claim 1,
The step of performing the scheduling,
When the resource region to which the control information to be decoded by the terminal is mapped in the second to n-th transmission unit time is fixed, the control information to be decoded by the terminal is scheduled using a common search space. Scheduling method. In claim 1,
The step of performing the scheduling,
And scheduling resources scheduled for the first terminal to the second terminal at the same time in the n-th transmission unit time interval in the first transmission unit time. A method in which a terminal receives control information simultaneously scheduled for consecutive first transmission unit intervals (TTI: Transmission Time Interval) to nth transmission unit intervals (where n is a natural number of 2 or more),
Performing blind decoding on the resource region to which the first control information is mapped in the first transmission unit period to check first control information; And
And checking second control information by performing decoding on a resource at a location indicated by the control information among resource regions included in the second to nth transmission unit intervals based on the checked first control information,
The first control information is mapped to a specific region among resource regions to which control information is mapped in the first transmission unit time, and the control information to be decoded by the terminal is mapped in each of the second to n-th transmission unit times. Control information receiving method of the terminal, characterized in that it includes the location information of. In claim 9,
The first control information is
A method for receiving control information of a terminal, comprising information on the number of transmission unit times scheduled at the same time. In claim 9,
The second control information comprises information dynamically changed from the first control information. In claim 11,
In the method for receiving control information of the terminal, after the terminal checks the second control information,
And applying the second control information to the first control information to reflect information dynamically changed in the first control information. In claim 9,
The second control information comprises at least one of information on a hybrid automatic repeat request (HARQ) process index, a new data indicator (NDI), and redundancy version (RV) information. Method of receiving control information. In claim 9,
Checking the second control information,
When the terminal does not have control information allocated to the terminal as a result of decoding a resource at a location indicated by the second control information in a predetermined transmission unit interval among the second to nth transmission unit intervals, the predetermined transmission A method for receiving control information of a terminal, characterized in that it is determined that resources are allocated to other terminals in a unit interval. In claim 9,
The method for receiving control information of the terminal,
And receiving downlink data in each transmission unit section based on the first control information and the second control information.

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