KR20140060439A - Apparatus and method of performing ue power saving operation based on discontinuous reception - Google Patents

Abstract

The present invention relates to an apparatus and a method for performing a terminal power saving operation based on discontinuous reception. The present specification discloses a power saving operation method of a terminal comprising the steps of enabling the terminal to transmit information related to power saving to a base station and receive DRX configuration information including a DRX_UL-HARQack field which supports the power saving operation based on the DRX from the base station. The terminal reduces generated power consumption by monitoring PDCCH during the activation time by terminating the activation time of unnecessary DRX in the early stages.

Description

[0001] APPARATUS AND METHOD OF PERFORMING UE POWER SAVING OPERATION BASED ON DISCONTINUOUS RECEPTION [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to wireless communication, and more particularly, to an apparatus and method for performing a power saving operation of a terminal based on discontinuous reception.

An automatic repeat request (ARQ) scheme transmits an acknowledgment (ACK) to a transmitter when the receiver correctly receives the data. If the receiver does not correctly receive the data, the receiver retransmits A Not Acknowledgment (NACK) is transmitted. In the HARQ scheme, an ACK / NACK signal transmitted by a receiver is generally represented by a small number of bits. Recently, a HARQ (Hybrid-ARQ) scheme, which is a technique combining channel coding of a physical layer with an existing ARQ scheme to improve transmission efficiency in data processing, has been proposed. The HARQ scheme, instead of retransmitting data that the transmitter has failed to receive, such as the conventional ARQ scheme, stores the data that the receiver failed to receive without discarding, and then combines the retransmitted data with the previously stored data to increase the performance gain. In the HARQ scheme, since the receiver uses a separate feedback radio resource for feedback of the ACK / NACK signal to the transmitter, efficient use of limited feedback radio resources is becoming an important issue.

According to the HARQ scheme, after transmitting (PUSCH) the uplink data through the uplink, the UE can not know whether or not the base station correctly received the uplink data. Accordingly, the UE keeps the uplink data in the HARQ buffer, and transmits the DRX activity time (i.e., the HARQ buffer time) so that the UE can receive the PDCCH including the retransmission request (transmission in the UL grant scheme) active time). The uplink data is continuously stored in the HARQ buffer even after receiving the HARQ ACK for uplink data from the base station. This is to respond to a request for retransmission of the uplink data from the base station after the UE receives the HARQ ACK. That is, the HARQ ACK can be interpreted to mean "waiting for first retransmission" rather than meaning that the BS successfully receives the UL data. Accordingly, since data is stored in the HARQ buffer until the HARQ maximum retransmission number is reached, the DRX state of the UE maintains the active time.

If a base station transmits an HARQ ACK to a mobile station and retransmits are not intended at all, but the mobile station still maintains its active time, the mobile station must continuously monitor the PDCCH. This causes a problem that unnecessary battery consumption of the terminal is caused. Therefore, there is a need for a method capable of reducing unnecessary battery consumption and realizing power saving of a terminal.

SUMMARY OF THE INVENTION The present invention provides an apparatus and method for performing a power saving operation of a terminal based on discontinuous reception.

It is another object of the present invention to provide an apparatus and method for transmitting DRX configuration information constituting a power saving operation of a terminal.

Another aspect of the present invention is to provide an apparatus and method for reducing power consumption of a UE by terminating an active time by flushing an HARQ buffer.

Another aspect of the present invention is to provide an apparatus and method for terminating an activity time of a base station HARQ ACK in adaptive retransmission, non-adaptive retransmission, or synchronized retransmission in an uplink HARQ performance.

According to an aspect of the present invention, there is provided a method of performing a power saving operation of a terminal based on discontinuous reception (DRX). The method includes receiving DRX configuration information from the base station, the DRX configuration information including power saving related information to a base station and a DRX_UL-HARQack field supporting a DRX-based power saving operation to the terminal .

The power saving operation flushes the HARQ buffer storing the uplink data when the DRX_UL-HARQack is configured in the UE and HARQ ACK for uplink data alone is received from the base station Step < / RTI >

According to another aspect of the present invention, there is provided a terminal for performing DRX-based power saving operations. The DRX configuration information includes a DRX_UL-HARQack field for supporting a power saving operation based on a DRX to the UE, an information generating unit for generating power saving related information, a transmission unit for transmitting the power saving related information to the base station, From the BS, and an HARQ controller for performing the power saving operation.

When the DRX_UL-HARQack is configured in the UE and the HARQ ACK for the uplink data is received from the BS, the power saving operation is performed by the HARQ controller, Flushing < / RTI >

According to another aspect of the present invention, there is provided a method for performing a power saving operation of a terminal based on DRX by a base station. The method includes receiving power saving related information from the terminal, determining whether to support a power saving operation for the terminal based on the power saving related information, and supporting the power saving operation based on DRX to the terminal And transmitting DRX configuration information including a DRX_UL-HARQack field to the UE.

Here, the power saving operation may be performed when the DRX_UL-HARQack is configured in the UE and the UE receives an HARQ ACK for uplink data from the Node B, and the UE stores the uplink data And flushing the HARQ buffer.

According to another aspect of the present invention, there is provided a base station for performing a power saving operation of a DRX-based terminal. The base station includes a receiver for receiving power saving related information from the terminal, a determining unit for determining whether to support a power saving operation for the terminal based on the power saving related information, a power saving operation based on the DRX, And a DRX configuration information and a transmission unit for transmitting the DRX configuration information and the HARQ ACK for uplink data to the UE. When the DRX_UL-HARQack is configured in the UE and the UE receives an HARQ ACK for uplink data alone from the Node B, the power saving operation is performed by the UE in the HARQ mode in which the UE stores the uplink data. And flushing the buffer.

The UE can reduce the power consumption by monitoring the PDCCH during the active time by terminating unnecessary DRX activity time early. In addition, the power saving of the UE can be realized by terminating the active time by flushing the HARQ buffer.

1 shows a wireless communication system to which the present invention is applied.
2 is a flowchart illustrating a power saving operation of a UE based on discontinuous reception according to an exemplary embodiment of the present invention.
3 is a flowchart illustrating a method for performing a power saving operation of a terminal by a terminal according to an exemplary embodiment of the present invention.
4 is a flowchart illustrating a method of performing a power saving operation of a terminal by a base station according to an exemplary embodiment of the present invention.
5 is a flowchart illustrating a power saving operation of a UE based on discontinuous reception according to another example of the present invention.
6 is a flowchart illustrating a method of performing a power saving operation of a terminal by a terminal according to another example of the present invention.
7 is a flowchart illustrating a method of performing a power saving operation of a terminal by a base station according to another example of the present invention.
8 is a block diagram illustrating a terminal and a base station according to a first embodiment of the present invention.
9 is a block diagram illustrating a terminal and a base station according to a second embodiment of the present invention.
10 is an explanatory diagram illustrating a DRX-based power saving operation according to an embodiment of the present invention.

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

In addition, the present invention will be described with respect to a wireless communication network. The work performed in the wireless communication network may be performed in a process of controlling a network and transmitting data by a system (e.g., a base station) Work can be done at a terminal connected to the network.

1 shows a wireless communication system to which the present invention is applied.

Referring to FIG. 1, a wireless communication system 10 is widely deployed to provide various communication services such as voice, packet data, and the like. The wireless communication system 10 includes at least one base station 11 (BS). Each base station 11 provides communication services to specific cells (15a, 15b, 15c). The cell may again be divided into multiple regions (referred to as sectors).

A mobile station (MS) 12 may be fixed or mobile and may be a user equipment (UE), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, (personal digital assistant), a wireless modem, a handheld device, and the like. The base station 11 may be called by other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, a femto base station, a home node B, . The cell should be interpreted in a generic sense to indicate a partial area covered by the base station 11 and is meant to cover various coverage areas such as a megacell, a macro cell, a microcell, a picocell, and a femtocell.

Hereinafter, downlink refers to communication from the base station 11 to the terminal 12, and uplink refers to communication from the terminal 12 to the base station 11. In the downlink, the transmitter may be part of the base station 11, and the receiver may be part of the terminal 12. In the uplink, the transmitter may be part of the terminal 12, and the receiver may be part of the base station 11. There are no restrictions on multiple access schemes applied to wireless communication systems. (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA , OFDM-CDMA, and the like. A TDD (Time Division Duplex) scheme in which uplink and downlink transmissions are transmitted using different time periods, or an FDD (Frequency Division Duplex) scheme in which they are transmitted using different frequencies can be used.

There are several physical control channels used in the physical layer. The physical downlink control channel (PDCCH) informs the UE of resource allocation of a paging channel (PCH), a downlink shared channel (DL-SCH), and hybrid automatic repeat request (HARQ) information related to the DL-SCH. The PDCCH may carry an uplink grant informing the UE of the resource allocation of the uplink transmission. A physical control format indicator channel (PCFICH) informs the UE of the number of OFDM symbols used for PDCCHs and is transmitted every subframe. The physical hybrid ARQ indicator channel (PHICH) is a downlink channel, and carries an HARQ ACK / NACK signal, which is a response of an uplink transmission. A physical uplink control channel (PUCCH) carries uplink control information such as an HARQ ACK / NACK signal for downlink transmission, a scheduling request, and a CQI. A physical uplink shared channel (PUSCH) carries an uplink shared channel (UL-SCH). A physical random access channel (PRACH) carries a random access preamble.

As described in the background art, the base station transmits the HARQ ACK to the UE and keeps uplink data in the HARQ buffer even if there is no intention of retransmission. The UE must still maintain the active time for monitoring the PDCCH continuously.

There are two main reasons for storing the uplink data in the HARQ buffer even after the UE receives the HARQ ACK.

First, it is to prevent a NACK-to-ACK error. The error that the UE determines that the data transmission is successful by incorrectly receiving the NACK transmitted by the Node B as the ACK due to the poor link performance between the Node B and the UE is referred to as a NACK-to-ACK error. If the UE flushes the HARQ buffer corresponding to the HARQ process transmitted immediately after receiving the ACK, the UE can not resend the retransmission even though the BS retransmits the request.

Secondly, the terminal has flexibility to request retransmission of the base station. The base station must be able to perform retransmission request control using only PDCCH and ACK / NACK (PHICH) signaling without uplink resource consumption. Only UL grant for UL retransmission and ACK / NACK exist for signaling that can be selected to control the retransmission request. Here, the uplink retransmission request is transmitted through the PDCCH, which increases the load on the PDCCH. Therefore, the base station must be able to use ACK / NACK signaling without resource consumption for retransmission request control.

Also, the base station may not be able to request retransmission for HARQ processes requiring HARQ retransmission due to traffic load or the like in a specific subframe. This is because a general HARQ process on the UE side makes a retransmission when it receives a NACK and when it receives an ACK it determines that the transmission is successful and does not prepare a retransmission to occur later. However, in the case of a wireless communication system in which the UL HARQ operation is operated in a synchronized manner, it is impossible to process a case in which retransmission is required for the corresponding HARQ process but the retransmission can not be requested in the current subframe. That is, it is impossible to retransmit the HARQ process. Because the synchronization operation scheme is a scheme in which the positions of subframes allocated to each HARQ process are fixed, the opportunity of retransmission for the HARQ process is limited to fixed subframe positions. Therefore, the mobile station expects a response of the base station to the fixed retransmission opportunity. However, considering ACK / NACK processing in the general HARQ process of the UE as described above, it is impossible to control the BS for delaying the retransmission for the corresponding HARQ process.

Therefore, even if the UE receives the HARQ ACK, i) the HARQ NACK can be received at the next retransmission time, and ii) the retransmission is possible. In order to defer retransmission of the HARQ process requiring retransmission, And after the problem situation such as a traffic load is released, it is possible to transmit the HARQ NACK and control the UE to retransmit the BS at a desired point in time.

For any reason, keeping the uplink data in the HARQ buffer in preparation for the retransmission of the base station even after receiving the HARQ ACK and operating the receiver to receive the retransmission request that may occur from the base station causes a problem of unnecessary battery consumption of the terminal have. Therefore, there is a need for a method capable of reducing unnecessary battery consumption and realizing power saving of a terminal.

≪ Embodiment 1 >

2 is a flowchart illustrating a power saving operation of a UE based on discontinuous reception according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the MS transmits power saving related information to a BS (S200). The power saving related information is a basic data used by the base station to determine whether or not to take a power saving operation for the terminal. The present embodiment may further include a step in which the terminal determines the necessity of the power saving operation before transmitting the power saving related information (not shown in the figure).

As an example, the power saving related information may include a power priority indicator (PPI) indicating that the terminal prefers configuration optimized for power saving. In this case, a procedure may be used in which the UE transmits a power priority indicator, which procedure may be referred to as a UE assistance information transmission procedure. When this procedure is used, although it is not shown in the drawing, before step S200, the base station may transmit the powerPrefIndication-Enabled field to the terminal including the powerPrefIndication-Enabled field in the RRC connection reconfiguration parameter powerPrefIndicationConfig field. This allows the terminal to transmit the power priority indicator through the terminal assistance information transmission procedure. In step S200, the terminal sets the power priority indicator to 'low power consumption' and transmits the power priority indicator to the base station by transmitting the power priority indicator to the base station.

As another example, the power saving related information may include signal strength information regarding the serving cell of the UE. Here, at least one of a reference signal received power (RSRP), a reference signal received quality (RSRQ), and an S-measure may be used as signal strength information regarding a serving cell of the UE. In addition, the final result value to which the offset information is added in addition to the signal strength information can be used as the power saving related information.

The reference value of the S-measure is one of the main configuration information (or indicators) that can measure the performance of the radio link between the serving cell and the UE. For example, if the signal strength information of the serving cell is greater than or equal to the reference value of the S-measure, the UE does not perform the signal strength measurement operation for the neighboring cell. On the other hand, if the signal strength information of the serving cell is less than or equal to the reference value of the S-measure, the UE performs the signal strength measurement operation for the neighboring cell. Then, the terminal transmits the result of the measurement operation to the base station as power saving related information as in step S200.

As another example, the power saving related information may be that the transmission is triggered based on a radio resource management (RRM) measurement report event. For example, when a specific RRM measurement report event (e.g., event 1A) is set for radio link performance deterioration determination and the event is triggered, the terminal transmits a measurement report to the base station as power saving related information as in step S200 .

Based on the power saving related information, the base station determines whether to support a power saving operation for the terminal (S205). For example, the base station can determine whether or not to support a power saving operation for a terminal that has transmitted a power priority indicator set to low power consumption as power saving related information. As another example, the base station may determine not only the power priority indicator, but also the power saving operation for the terminal, considering the signal strength for the serving cell described above. For example, the base station may decide to support power saving operations for terminals that have a sufficiently strong signal strength for the serving cell. As another example, if the base station determines that the radio link performance between the terminal and the base station is deteriorated in the future, the base station can determine that the base station supports the power saving operation. For example, when the signal strength information of the serving cell has a value lower than the S-measure reference value or a measurement report based on the RRM measurement report event set for the radio link performance deterioration determination is received from the UE, It may be determined to support a power saving operation. Also, the base station may determine to support the power saving operation for the UE based on the signal strength information of the serving cell secured through the periodic RRM measurement report.

If the base station determines to support a power saving operation for the terminal, the base station may generate DRX configuration information including a field indicating that power saving operation is supported (S210). Here, a field indicating that the power saving operation is supported may be indicated by a DRX_UL-HARQack field. The DRX_UL-HARQack field may be defined as configuration information that can terminate an active time when receiving an HARQ ACK for uplink transmission. The DRX configuration information including the DRX_UL-HARQack field may be defined, for example, as shown in the following table.

MAC-MainConfig :: = SEQUENCE { ... DRX-Config_1 DRX-Config_1 OPTIONAL, - Cond DRX_1 ... DRX-Config_2 DRX-Config_2 OPTIONAL - Cond DRX_2 DRX_UL-HARQack ENUMERATED {support} OPTIONAL - Cond DRX-config }

Referring to Table 1, the DRX configuration information includes a first DRX Config field (DRX Config_1) defining DRX operation parameters for the UE and a second DRX Config field (DRX Config_1) including DRX operation parameters according to inter device coexistance Field (DRX Config_2). That is, if the first DRX Config field is included in the DRX configuration information, the second DRX Config field is not included in the DRX configuration information. Also, if the second DRX Config field is included in the DRX configuration information, the first DRX Config field is not included in the DRX configuration information. For example, the first DRX Config field indicates a DRX config corresponding to release version 8 in the LTE system and the second DRX Config field indicates a DRX config corresponding to the release version 11 in the LTE system . In the case where only the first DRX-config is used for the non-IDC irrespective of the release version, the conditional presence for the first DRX-config can be similarly defined. Or DRX_UL-HARQack field may be defined as one of DRX_1 or DRX_2.

The DRX_UL-HARQack field may be selectively included in the DRX configuration information only when the first DRX Config field or the second DRX Config field is included in the DRX configuration information. If the base station determines to support a power saving operation for the UE, the base station includes the DRX_UL-HARQack field in the DRX configuration information as shown in Table 1 above. On the other hand, if the base station decides not to support the power saving operation for the UE, the base station does not include the DRX_UL-HARQack field in Table 1 above.

The base station transmits the DRX configuration information generated in step S210 to the mobile station (S215).

Upon receiving the DRX configuration information from the base station, the UE confirms that DRX_UL-HARQack is present in the DRX configuration information, and the UE configures a DRX_UL-HARQack (S220). The transmission and configuration of the DRX_UL-HARQack is performed at the RRC layer level and is completed using the RRC connection reconfiguration procedure. For example, the DRX configuration information in step S215 is included in the RRC connection reconfiguration message and is transmitted from the base station to the UE, and the DRX_UL-HARQack configuration in step S220 corresponds to the RRC connection reconfiguration of the UE.

The BS transmits an HARQ ACK for the uplink data received from the MS to the MS (S225). Although not shown in the figure, the present embodiment includes a step of receiving, from the base station, an uplink grant (including a new data indicator) for transmitting new uplink data to the base station before step S225, And transmitting the uplink data to the base station using uplink resources allocated by the uplink grant. The HARQ ACK may be mapped to the PHICH and transmitted to the UE. The base station can transmit the HARQ ACK only when the retransmission of the corresponding HARQ process is not required for the UE having the DRX_UL-HARQack structure.

When the UE receives the HARQ ACK in the DRX_UL-HARQack configured state, the UE performs a power saving operation (S230). That is, the power saving operation requires that DRX_UL-HARQack is configured in the UE and that the UE receives HARQ ACK alone for the uplink HARQ data from the base station. Receiving only the HARQ ACK may mean receiving only the HARQ ACK without receiving the UL grant.

Specifically, the power saving operation can be defined as the following operation.

As an example, the power saving operation includes the step of flushing the HARQ buffer in which the UE stores the uplink data. The HARQ buffer is managed by the MAC layer of the UE. Therefore, if the MAC layer receives the HARQ ACK and confirms that the DRX_UL-HARQack is configured in the RRC layer, the HARQ buffer can be flushed. Of course, the HARQ buffer may be flushed even after retransmission of the HARQ maximum retransmission number of the UE. However, this is different from the HARQ buffer flush caused by the DRX_UL-HARQack configuration.

Flushing the HARQ buffer affects the DRX operation. This is because the activity time in the DRX operation is determined by i) a DRX-related timer (onduration timer, DRX inactivity timer, DRX retransmission timer or MAC contention resolution timer) (ii) a time during which a scheduling request is transmitted and pending on the PUCCH, and (iii) an uplink grant for pending HARQ retransmission may occur and the data in the corresponding HARQ buffer Can be defined as the time at which the < RTI ID = 0.0 > iii) With respect to the active time of the condition, if the UE flushes the HARQ buffer as in step S230, the data is no longer present in the HARQ buffer, and the UE is not in the active time unless other conditions are satisfied . That is, the terminal ends the activity time. From this point of view, the power saving operation may mean that the terminal ends its activity time.

In this manner, the UE can reduce the power consumption caused by monitoring the PDCCH during the active time by terminating the unnecessary DRX activity time prematurely.

3 is a flowchart illustrating a method for performing a power saving operation of a terminal by a terminal according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the terminal transmits power saving related information to a base station (S300). The power saving related information is the basic data used by the base station to determine whether to take power saving operation for the terminal. The present embodiment may further include a step of confirming the necessity of the power saving operation before the terminal transmits power saving related information before step S300 (not shown in the figure).

As an example, the power saving related information may include a power priority indicator (PPI) indicating that the terminal prefers an optimized configuration for power saving. In this case, a procedure may be used in which the terminal transmits a power priority indicator, which procedure may be called a terminal ancillary information transmission procedure. If this procedure is used, although not shown in the drawing, before step S300, the UE can receive a powerPrefIndicationConfig field containing the powerPrefIndicatino-Enabled field from the base station. The terminal is allowed to transmit the power priority indicator through the terminal ancillary information transmission procedure. In step S300, the terminal sets the power priority indicator to 'low power consumption', and transmits the power priority indicator to the base station by transmitting the power priority indicator to the terminal side information.

As another example, the power saving related information may include signal strength information regarding the serving cell of the UE. Here, at least one of a reference signal band reception signal (RSRP), a reference signal band reception quality (RSRQ), and an S-measure may be used as signal strength information regarding a serving cell of the UE.

The reference value of the S-measure is one of the main configuration information (or indicators) that can measure the performance of the radio link between the serving cell and the UE. For example, if the signal strength information of the serving cell is greater than or equal to the reference value of the S-measure, the UE does not perform the signal strength measurement operation for the neighboring cell. On the other hand, if the signal strength information of the serving cell is less than or equal to the reference value of the S-measure, the UE performs the signal strength measurement operation for the neighboring cell. In step S300, the terminal transmits the result of the measurement operation to the base station as power saving related information.

As another example, the power saving related information may be that the transmission is triggered based on the RRM measurement report event. For example, when a specific RRM measurement report event (for example, event 1A) is set for radio link performance deterioration determination and the event is triggered, the terminal transmits a measurement report to the base station as power saving related information as in step S300 .

If the base station determines whether or not to support the power saving operation for the UE, the UE receives the DRX configuration information including the field indicating that the power saving operation is supported from the base station (S305). A field indicating that the power saving operation is supported may be indicated by a DRX_UL-HARQack field. The DRX_UL-HARQack field may be defined as configuration information that can terminate an active time when receiving an HARQ ACK for uplink transmission. The DRX configuration information including the DRX_UL-HARQack field may be defined as shown in Table 1, for example.

If it is confirmed that DRX_UL-HARQack is present in the DRX configuration information, the UE configures DRX_UL-HARQack (S310). The configuration of DRX_UL-HARQack is performed at the RRC layer level and is completed using the RRC connection reconfiguration procedure. For example, the DRX configuration information in step S305 is included in the RRC connection reconfiguration message and is transmitted from the base station to the UE, and the DRX_UL-HARQack configuration in step S310 corresponds to the RRC connection reconfiguration of the UE.

The MS receives a HARQ ACK for uplink data transmitted from the BS to the BS (S315). Although not shown in the figure, the present embodiment includes a step of receiving, from the base station, an uplink grant (including a new data indicator) for transmitting new uplink data to a base station before step S315, And transmitting the uplink data to the base station using uplink resources allocated by the uplink grant.

When the UE receives the HARQ ACK in the DRX_UL-HARQack configured state, the UE performs a power saving operation (S320). That is, the power saving operation requires that DRX_UL-HARQack is configured in the UE and that the UE receives HARQ ACK alone for the uplink HARQ data from the base station. Receiving only the HARQ ACK may mean receiving only the HARQ ACK without receiving the UL grant.

Specifically, the power saving operation can be defined as the following operation.

As an example, the power saving operation includes flushing the HARQ buffer in which the UE stores the uplink data. The HARQ buffer is managed by the MAC layer of the UE. Therefore, if the MAC layer receives the HARQ ACK and confirms that the DRX_UL-HARQack is configured in the RRC layer, the HARQ buffer can be flushed.

Flushing the HARQ buffer affects the DRX operation. This is because the activity time in the DRX operation is i) the time during which the DRX related timer (persistent interval timer, DRX inactivity timer, DRX retransmission timer or MAC contention resolution timer) is in progress, ii) the scheduling request is transmitted on the PUCCH, , And iii) an uplink grant for pending HARQ retransmission may occur and the time at which data in the corresponding HARQ buffer is present may be defined. iii) With respect to the active time of the condition, if the UE flushes the HARQ buffer as in step S320, the data is no longer present in the HARQ buffer, and the UE is not in the active time unless other conditions are satisfied . That is, the terminal ends the activity time. From this point of view, the power saving operation may mean that the terminal ends its activity time.

If it is determined in step S305 that the DRX_UL-HARQack does not exist in the DRX configuration information received by the UE, the UE performs a DRX operation according to the existing DRX configuration and does not change its activity time. Therefore, even if the HARQ ACK is received in step S315, the UE does not flush the HARQ buffer but keeps the previous uplink data in the HARQ buffer continuously, and does not perform a separate power saving operation. That is, since the activity time in the DRX is not terminated, the UE continuously performs PDCCH monitoring.

4 is a flowchart illustrating a method of performing a power saving operation of a terminal by a base station according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the base station receives power saving related information from the terminal (S400). The power saving related information is the basic data used by the base station to determine whether to take power saving operation for the terminal.

As an example, the power saving related information may include a power priority indicator (PPI) indicating that the terminal prefers an optimized configuration for power saving. In this case, a procedure may be used in which the base station receives the power priority indicator, which procedure may be referred to as a terminal ancillary information transmission procedure. If this procedure is used, this embodiment may further include a step in which the base station includes a powerPrefIndication-Enabled field in the powerPrefIndicationConfig field, which is an RRC connection reconfiguration parameter, to the terminal before step S400. This allows the terminal to transmit the power priority indicator through the terminal assistance information transmission procedure.

As another example, the power saving related information may include signal strength information regarding the serving cell of the UE. Here, at least one of a reference signal band reception signal (RSRP), a reference signal band reception quality (RSRQ), and an S-measure may be used as signal strength information regarding a serving cell of the UE.

The reference value of the S-measure is one of the main configuration information (or indicators) that can measure the performance of the radio link between the serving cell and the UE. For example, if the signal strength information of the serving cell is greater than or equal to the reference value of the S-measure, the UE does not perform the signal strength measurement operation for the neighboring cell. On the other hand, if the signal strength information of the serving cell is less than or equal to the reference value of the S-measure, the UE performs the signal strength measurement operation for the neighboring cell. Then, the base station receives the result of the measurement operation from the terminal as power saving related information as in step S400.

As another example, the power saving related information may be that the transmission is triggered based on the RRM measurement report event. For example, when a specific RRM measurement report event (for example, event 1A) is set for radio link performance deterioration determination, and the event is triggered, the base station receives the measurement report from the terminal as power saving related information as in step S400 .

Based on the power saving related information, the base station determines whether to support a power saving operation for the terminal (S405). For example, the base station can determine whether or not to support a power saving operation for a terminal that has transmitted a power priority indicator set to low power consumption as power saving related information. As another example, the base station may determine not only the power priority indicator, but also the power saving operation for the terminal, considering the signal strength for the serving cell described above. For example, the base station may decide to support power saving operations for terminals that have a sufficiently strong signal strength for the serving cell. As another example, if the base station determines that the radio link performance between the terminal and the base station is deteriorated in the future, the base station can determine that the base station supports the power saving operation. For example, when the signal strength information of the serving cell has a value lower than the S-measure reference value or a measurement report based on the RRM measurement report event set for the radio link performance deterioration determination is received from the UE, It may be determined to support a power saving operation.

If the base station determines to support a power saving operation for the terminal, the base station may generate DRX configuration information including a field indicating that power saving operation is supported (S410). Here, a field indicating that the power saving operation is supported may be indicated by a DRX_UL-HARQack field. The DRX_UL-HARQack field may be defined as configuration information that can terminate an active time when receiving an HARQ ACK for uplink transmission. The DRX configuration information including the DRX_UL-HARQack field may be defined as shown in Table 1, for example.

The base station includes a first DRX Config field (DRX Config_1) defining DRX operation parameters related to the UE and a second DRX Config field (DRX Config_2) defining DRX operation parameters according to inter device coexistance (IDC) May be included in the DRX configuration information. That is, if the base station includes the first DRX Config field in the DRX configuration information, the base station can not include the second DRX Config field in the DRX configuration information. Also, if the base station includes the second DRX Config field in the DRX configuration information, the base station can not include the first DRX Config field in the DRX configuration information. For example, the first DRX Config field indicates a DRX config corresponding to release version 8 in the LTE system and the second DRX Config field indicates a DRX config corresponding to the release version 11 in the LTE system . In the case where only the first DRX-config is used for the non-IDC irrespective of the release version, the conditional presence for the first DRX-config can be similarly defined. Or DRX_UL-HARQack field may be defined as one of DRX_1 or DRX_2.

The base station can selectively include the DRX_UL-HARQack field in the DRX configuration information only when the first DRX Config field or the second DRX Config field is included in the DRX configuration information. If the base station determines to support a power saving operation for the UE, the base station includes the DRX_UL-HARQack field in the DRX configuration information as shown in Table 1 above. On the other hand, if the base station decides not to support the power saving operation for the UE, the base station does not include the DRX_UL-HARQack field in Table 1 above.

The base station transmits the DRX configuration information generated in step S410 to the terminal (S415). Upon receiving the DRX configuration information from the base station, the UE confirms that the DRX_UL-HARQack exists in the DRX configuration information, and the UE configures the DRX_UL-HARQack. The transmission and configuration of the DRX_UL-HARQack is performed at the RRC layer level and is completed using the RRC connection reconfiguration procedure. For example, the DRX configuration information in step S415 is included in the RRC connection reconfiguration message and is transmitted from the BS to the UE, and the DRX_UL-HARQack configuration of the UE corresponds to the reconfiguration of the RRC connection of the UE.

The BS transmits an HARQ ACK for the uplink data received from the MS to the MS (S420). Although not shown in the figure, the present embodiment includes a step of transmitting, to the terminal, an uplink grant (including a new data indicator) for receiving new uplink data from a terminal before step S420, And receiving the uplink data from the terminal through the uplink resource allocated by the uplink grant. The HARQ ACK may be mapped to the PHICH and transmitted to the UE. The base station can transmit the HARQ ACK only when the retransmission of the corresponding HARQ process is not required for the UE having the DRX_UL-HARQack structure.

FIGS. 2 to 4 illustrate a power saving operation method of the UE based on the DRX_UL-HARQack field indicating that the power saving operation is supported. That is, the support of the power saving operation is configured to limit the DRX operation.

However, the HARQ maximum retransmission count field, which is a parameter existing in the configuration field of the uplink shared channel, may be used as a field indicating that the power saving operation is supported. Hereinafter, a second embodiment supporting the power saving operation of the UE based on the HARQ maximum retransmission count will be described.

≪ Embodiment 2 >

5 is a flowchart illustrating a power saving operation of a UE based on discontinuous reception according to another example of the present invention.

Referring to FIG. 5, the terminal transmits power saving related information to a base station (S500). The operation related to step S500 and its subsequent operation include the technical ideas and embodiments described in step S200.

Based on the power saving related information, the base station determines whether to support a power saving operation for the terminal (S505). The operation related to step S505 and its subsequent operation include the technical ideas and embodiments described in step S205.

If the base station determines to support the power saving operation for the UE, the base station sets the value of the HARQ maximum retransmission count (maxHARQ-Tx) field, which is a field indicating that the power saving operation is supported, to 'Infinity' (S510). That is, a field indicating that the power saving operation is supported may be indicated as a parameter in the field maxHARQ-Tx, which is a field indicating the maximum number of times for uplink retransmission.

The superficial meaning of the maxHARQ-Tx field value set to 'infinity' is that the terminal can continue to retransmit as long as the base station requests retransmission. However, its intrinsic meaning may include supporting or commanding a power saving operation upon receipt of an HARQ ACK for an uplink transmission from a base station. Therefore, a UE set to maxHARQ-Tx = 'infinity' can terminate the scheduled retransmission and perform a power saving operation upon receiving an HARQ ACK.

The uplink common channel configuration information (ul-SCH-Config) including the maxHARQ-Tx field set to 'infinity' can be defined, for example, as shown in the following table.

ul-SCH-Config SEQUENCE { maxHARQ-Tx ENUMERATED { n1, n2, n3, n4, n5, n6, n7, n8, n10, n12, n16, n20, n24, n28, infinity, spare1} OPTIONAL, - Need ON ... }

Referring to Table 2, the uplink common channel configuration (ul-SCH-Config) field includes the maxHARQ-TX field, and the values that the maxHARQ-TX field can have are n1, n2, ... , n24, n28, infinity, and spare1. In the present embodiment, a value indicating that the power saving operation is supported through the maxHARQ-Tx field is expressed as infinity. However, the present invention is not limited to this and can be expressed in other terms. Is included in the technical idea of the present invention.

The base station transmits the uplink shared channel configuration information including the maxHARQ-Tx field set to 'infinity' to the terminal (S515). The uplink common channel configuration information may be included in the MAC main configuration (a kind of RRC message) and transmitted to the UE. The transmission and configuration of maxHARQ-TX is performed at the RRC layer level and is completed using the RRC connection reconfiguration procedure. For example, the uplink shared channel configuration information including maxHARQ-TX in step S515 is included in the RRC connection reconfiguration message and is transmitted from the base station to the UE, and the maxHARQ-TX configuration in step S520 corresponds to the RRC connection reconfiguration of the UE .

The BS transmits an HARQ ACK for the uplink data received from the MS to the MS (S525). Although not shown in the drawing, the present embodiment includes a step of receiving, from the base station, an uplink grant (including a new data indicator) for transmitting new uplink data to the base station before step S525; And transmitting the uplink data to the base station using the allocated uplink resources. The HARQ ACK may be mapped to the PHICH and transmitted to the UE.

When the UE receives the HARQ ACK in the state of maxHARQ-TX = 'infinity', the UE performs a power saving operation (S530). That is, the power saving operation requires that maxHARQ-TX = 'infinity' is configured in the UE and that the UE receives only HARQ ACK for the uplink HARQ data from the base station. Receiving only the HARQ ACK may mean receiving only the HARQ ACK without receiving the UL grant.

Specifically, the power saving operation can be defined as the following operation.

As an example, the power saving operation includes the step of flushing the HARQ buffer in which the UE stores the uplink data. The HARQ buffer is managed by the MAC layer of the UE. Accordingly, if the MAC layer receives the HARQ ACK and confirms that maxHARQ-TX = 'infinity' is configured in the RRC layer, the HARQ buffer can be flushed.

Flushing the HARQ buffer affects the DRX operation. This is because the activity time in the DRX operation is the time during which the DRX-related timer (persistent interval timer, DRX inactivity timer, DRX retransmission timer or MAC contention resolution timer) is in progress, ii) the scheduling request is transmitted on the PUCCH, And iii) an uplink grant for pending HARQ retransmission may occur and the data in the corresponding HARQ buffer may be defined as the time at which the data exists. iii) With respect to the active time of the condition, if the UE flushes the HARQ buffer as in step S530, the data is no longer present in the HARQ buffer, and the UE is not in the active time unless other conditions are satisfied . That is, the terminal ends the activity time. From this point of view, the power saving operation may mean that the terminal ends its activity time.

6 is a flowchart illustrating a method of performing a power saving operation of a terminal by a terminal according to another example of the present invention.

Referring to FIG. 6, the terminal transmits power saving related information to a base station (S600). The operation related to step S600 and its subsequent operation include the technical ideas and embodiments described in step S300.

The UE receives the uplink shared channel configuration information including the maxHARQ-Tx field set to 'infinity' from the base station (S605). The uplink common channel configuration information may be included in the MAC main configuration (a kind of RRC message) and transmitted to the UE. The transmission and configuration of maxHARQ-TX is performed at the RRC layer level and is completed using the RRC connection reconfiguration procedure. For example, the uplink shared channel configuration information including maxHARQ-TX in step S605 is included in the RRC connection reconfiguration message and is transmitted from the base station to the UE, and the maxHARQ-TX configuration in step S610 corresponds to the RRC connection reconfiguration of the UE .

The UE receives the HARQ ACK for the uplink data from the Node B (S615). Although not shown in the drawing, the present embodiment includes a step of receiving, from the base station, an uplink grant (including a new data indicator) for transmitting new uplink data to the base station before step S615; And transmitting the uplink data to the base station using the allocated uplink resources.

If the UE receives the HARQ ACK in the state of maxHARQ-TX = 'infinity', the UE performs a power saving operation (S620). That is, the power saving operation requires that maxHARQ-TX = 'infinity' is configured in the UE and that the UE receives only HARQ ACK for the uplink HARQ data from the base station. Receiving only the HARQ ACK may mean receiving only the HARQ ACK without receiving the UL grant.

Specifically, the power saving operation can be defined as the following operation.

As an example, the power saving operation includes flushing the HARQ buffer in which the UE stores the uplink data. The HARQ buffer is managed by the MAC layer of the UE. Accordingly, if the MAC layer receives the HARQ ACK and confirms that maxHARQ-TX = 'infinity' is configured in the RRC layer, the HARQ buffer can be flushed.

Flushing the HARQ buffer affects the DRX operation. This is because the activity time in the DRX operation is the time during which the DRX-related timer (persistent interval timer, DRX inactivity timer, DRX retransmission timer or MAC contention resolution timer) is in progress, ii) the scheduling request is transmitted on the PUCCH, And iii) an uplink grant for pending HARQ retransmission may occur and the data in the corresponding HARQ buffer may be defined as the time at which the data exists. iii) With respect to the active time of the condition, if the UE flushes the HARQ buffer as in step S620, the data is no longer present in the HARQ buffer, so that the UE is not in the active time unless other conditions are satisfied . That is, the terminal ends the activity time. From this point of view, the power saving operation may mean that the terminal ends its activity time.

7 is a flowchart illustrating a method of performing a power saving operation of a terminal by a base station according to another example of the present invention.

Referring to FIG. 7, the base station receives power saving related information from the terminal (S700). The operation related to step S700 and its subsequent operation include the technical ideas and embodiments described in step S400.

Based on the power saving related information, the base station determines whether to support a power saving operation for the terminal (S705). The operation related to step S705 and its subsequent operation include the technical ideas and embodiments described in step S405.

If the base station determines to support the power saving operation for the UE, the base station sets the value of the HARQ maximum retransmission count (maxHARQ-Tx) field, which is a field indicating that the power saving operation is supported, to 'Infinity' (S710). That is, a field indicating that the power saving operation is supported may be indicated as a parameter in the field maxHARQ-Tx, which is a field indicating the maximum number of times for uplink retransmission.

The superficial meaning of the maxHARQ-Tx field value set to 'infinity' is that the terminal can continue to retransmit as long as the base station requests retransmission. However, its intrinsic meaning may include supporting or commanding a power saving operation upon receipt of an HARQ ACK for an uplink transmission from a base station. Therefore, a UE set to maxHARQ-Tx = 'infinity' can terminate the scheduled retransmission and perform a power saving operation upon receiving an HARQ ACK.

The uplink shared channel configuration information (ul-SCH-Config) including the maxHARQ-Tx field set to 'infinity' may be defined as shown in Table 2, for example.

The base station transmits the uplink shared channel configuration information including the maxHARQ-Tx field set to 'infinity' to the terminal (S715). The uplink common channel configuration information may be included in the MAC main configuration (a kind of RRC message) and transmitted to the UE. The transmission and configuration of maxHARQ-TX is performed at the RRC layer level and is completed using the RRC connection reconfiguration procedure.

The BS transmits an HARQ ACK for the uplink data received from the MS to the MS (S720). Although not shown in the figure, the present exemplary embodiment includes a step in which a base station transmits an uplink grant (including a new data indicator) for transmitting new uplink data to a base station before the step S720, The base station may receive the uplink data from the terminal using the uplink resource allocated by the uplink resource. The HARQ ACK may be mapped to the PHICH and transmitted to the UE.

When the UE receives the HARQ ACK in the state of maxHARQ-TX = 'infinity', the UE performs a power saving operation. That is, the power saving operation requires that maxHARQ-TX = 'infinity' is configured in the UE and that the UE receives only HARQ ACK for the uplink HARQ data from the base station. Receiving only the HARQ ACK may mean receiving only the HARQ ACK without receiving the UL grant.

Specifically, the power saving operation can be defined as the following operation.

As an example, the power saving operation includes the step of flushing the HARQ buffer in which the UE stores the uplink data. The HARQ buffer is managed by the MAC layer of the UE. Accordingly, if the MAC layer receives the HARQ ACK and confirms that maxHARQ-TX = 'infinity' is configured in the RRC layer, the HARQ buffer can be flushed.

Flushing the HARQ buffer affects the DRX operation. This is because the activity time in the DRX operation is the time during which the DRX-related timer (persistent interval timer, DRX inactivity timer, DRX retransmission timer or MAC contention resolution timer) is in progress, ii) the scheduling request is transmitted on the PUCCH, And iii) an uplink grant for pending HARQ retransmission may occur and the data in the corresponding HARQ buffer may be defined as the time at which the data exists. iii) With respect to the active time of the condition, if the UE flushes the HARQ buffer as in step S530, the data is no longer present in the HARQ buffer, and the UE is not in the active time unless other conditions are satisfied . That is, the terminal ends the activity time. From this point of view, the power saving operation may mean that the terminal ends its activity time.

8 is a block diagram illustrating a terminal and a base station according to a first embodiment of the present invention.

Referring to FIG. 8, a terminal 800 includes a receiving unit 805, a terminal processor 810, and a transmitting unit 815. The terminal processor 810 further includes an information generator 811 and an HARQ controller 812.

The information generation unit 811 generates power saving related information. The power saving related information is a basic data used by the base station 850 to determine whether to perform a power saving operation on the terminal 800. [ The information generating unit 811 can determine the necessity of the power saving operation for the terminal 800 before generating the power saving related information.

As an example, the information generation unit 811 may generate power saving related information including a power priority indicator (PPI) indicating that the configuration optimized for the power saving of the terminal is preferred. The procedure by which the transmitting unit 815 transmits the power priority indicator may be referred to as a terminal auxiliary information transmission procedure. If this procedure is used, the receiver 805 may first receive from the base station 850 a powerPrefIndicationConfig field that includes a powerPrefIndicatino-Enabled field. The terminal 800 is allowed to transmit the power priority indicator to the base station 850 through the terminal ancillary information transmission procedure.

Then, the information generating unit 811 sets the power priority indicator to 'low power consumption', generates the terminal side information including the power priority indicator, and sends the terminal side information to the transmitter 815, May transmit terminal assistance information to the base station (850).

As another example, the information generating unit 811 may generate power saving related information including signal strength information regarding the serving cell of the terminal 800. [ Here, at least one of the reference signal band reception signal RSRP, the reference signal band reception quality RSRQ, and the S-measure may be used as the signal strength information regarding the serving cell of the terminal 800.

The reference value of the S-measure is one of the main configuration information (or indicators) that can measure the radio link performance between the serving cell and the UE 800. For example, if the signal strength information of the serving cell is equal to or greater than the reference value of the S-measure, the information generating unit 811 does not perform the signal strength measurement operation for the neighboring cell. On the other hand, when the signal strength information of the serving cell is less than or equal to the reference value of the S-measure, the information generation unit 811 performs a signal strength measurement operation for the neighboring cell. When the information generating unit 811 generates the power saving related information as the power saving related information and sends the result to the transmitting unit 815, the transmitting unit 815 transmits the power saving related information to the base station 850.

As another example, the information generating unit 811 may generate power saving related information whose transmission is triggered based on an RRM measurement report event. For example, when a specific RRM measurement report event (for example, event 1A) is set for the radio link performance deterioration determination and the event is triggered, the information generation unit 811 generates a measurement report as power saving related information, Unit 815, the transmitter 815 transmits the power saving related information to the base station 850.

Receiver 805 receives DRX configuration information from base station 850 that includes a field indicating that it supports power saving operations. A field indicating that the power saving operation is supported may be indicated by a DRX_UL-HARQack field. The DRX_UL-HARQack field may be defined as configuration information that can terminate an active time when receiving an HARQ ACK for uplink transmission. The DRX configuration information including the DRX_UL-HARQack field may be defined as shown in Table 1, for example.

If the DRX_UL-HARQ_ACK is present in the DRX configuration information, the information generating unit 811 constructs DRX_UL-HARQack. The configuration of the DRX_UL-HARQack is performed at the RRC layer level of the UE 800 and can be completed using the RRC connection reconfiguration procedure. For example, the DRX configuration information is included in the RRC connection reconfiguration message and is received by the reception unit 805, and the DRX_UL-HARQack configuration corresponds to the RRC connection reconfiguration of the information generation unit 811.

The transmitting unit 815 transmits the uplink data to the base station 850 and the receiving unit 805 receives the HARQ ACK for the uplink data from the base station 850. In this embodiment, the receiving unit 805 receives from the base station 850 an uplink grant (including a new data indicator) for transmitting new uplink data to the base station 850, and the transmitting unit 815 transmits the uplink grant And transmitting the uplink data to the base station 850 using the uplink resources allocated by the uplink resources.

When the HARQ ACK is received by the receiver 805 in a state in which DRX_UL-HARQack is configured, the HARQ controller 812 performs a power saving operation. That is, the power saving operation is conditional on that DRX_UL-HARQack is configured in the UE 800 and that the receiving unit 805 receives HARQ ACK alone for the uplink HARQ data from the BS 850. Receiving only the HARQ ACK may mean that the receiving unit 805 receives only the HARQ ACK without receiving the UL grant.

Specifically, the power saving operation can be defined as the following operation.

As an example, the power saving operation includes a process of flushing the HARQ buffer in which the HARQ controller 812 stores the uplink data. The HARQ buffer is managed by the MAC layer of the UE 800. [ Accordingly, when the MAC layer receives the HARQ ACK and confirms that the DRX_UL-HARQack is configured in the RRC layer, the HARQ controller 812 can flush the HARQ buffer.

Flushing the HARQ buffer affects the DRX operation. This is because the activity time in the DRX operation is i) the time during which the DRX related timer (persistent interval timer, DRX inactivity timer, DRX retransmission timer or MAC contention resolution timer) is in progress, ii) the scheduling request is transmitted on the PUCCH, , And iii) an uplink grant for pending HARQ retransmission may occur and the time at which data in the corresponding HARQ buffer is present may be defined. iii) When the HARQ control unit 812 flushes the HARQ buffer with respect to the active time of the condition, the data is no longer present in the HARQ buffer. Therefore, unless the other conditions are satisfied, . That is, the activity time of the terminal 800 is terminated. From this point of view, the power saving operation may mean that the HARQ control unit 812 ends the active time.

If the receiver 805 confirms that the DRX_UL-HARQack does not exist in the DRX configuration information received by the receiver 805, the HARQ controller 812 performs the DRX operation according to the existing DRX configuration and does not change the activity time. Therefore, even if the HARQ controller 812 receives the HARQ ACK, the HARQ controller 812 keeps the previous uplink data in the HARQ buffer without flushing the HARQ buffer, and does not perform a separate power saving operation. That is, since the activity time in the DRX is not terminated, the HARQ controller 812 continuously monitors the PDCCH.

The base station 850 includes a transmitter 855, a base station processor 860, and a receiver 865. The base station processor 860 again includes an information generating unit 862 and a determining unit 861. [

Receiving unit 865 receives power saving related information from terminal 800. The power saving related information is basic data used by the determination unit 861 to determine whether or not the terminal 800 should perform a power saving operation.

As an example, the power saving related information may include a power priority indicator (PPI) indicating that the terminal 800 prefers an optimized configuration for power saving. In this case, a procedure may be used in which the receiver 865 receives the power priority indicator, which procedure may be referred to as a terminal ancillary information transmission procedure. When this procedure is used, the present embodiment generates a powerPrefIndicationConfig field including the powerPrefIndicatino-Enabled field, and the transmitting unit 855 transmits the powerPrefIndicationConfig field to the terminal 800 .

As another example, the power saving related information may include signal strength information regarding the serving cell of the terminal 800. Here, at least one of the reference signal band reception signal RSRP, the reference signal band reception quality RSRQ, and the S-measure may be used as the signal strength information regarding the serving cell of the terminal 800.

As another example, the power saving related information may be that the transmission is triggered based on the RRM measurement report event. For example, when a specific RRM measurement report event (e.g., event 1A) is set for radio link performance deterioration determination and the event is triggered, the receiver 865 also sends a measurement report as power saving related information to the terminal 800 Lt; / RTI >

The determination unit 861 determines whether to support a power saving operation for the terminal 800 based on the power saving related information. As an example, the determination unit 861 can determine whether or not the power saving operation for the terminal 800 that transmitted the power priority indicator set for low power consumption as power saving related information is supported. As another example, the determination unit 861 can determine whether to support the power saving operation for the terminal 800 in consideration of the signal strength for the serving cell as well as the power priority indicator. For example, for a terminal 800 having a sufficiently strong signal strength with respect to a serving cell, the determination unit 861 can determine to support a power saving operation. As another example, when the determination unit 861 determines that the radio link performance between the terminal and the base station is deteriorated in the future, the determination unit 861 can determine that the terminal 800 supports the power saving operation . For example, if the signal strength information of the serving cell has a value lower than the S-measure reference value or a measurement report based on the RRM measurement report event set for radio link performance deterioration determination is received from the terminal 800, 800), the determination unit 861 can determine to support the power saving operation.

If the determination unit 861 decides to support the power saving operation for the terminal 800, the information generation unit 862 may generate DRX configuration information including a field indicating that the power saving operation is supported. Here, a field indicating that the power saving operation is supported may be indicated by a DRX_UL-HARQack field. The DRX_UL-HARQack field may be defined as configuration information that can terminate an active time when receiving an HARQ ACK for uplink transmission. The DRX configuration information including the DRX_UL-HARQack field may be defined as shown in Table 1, for example.

The information generation unit 862 generates a first DRX Config field DRX Config_1 defining DRX operation parameters for the UE and a second DRX Config field DRX Config1 defining DRX operation parameters according to an inter device coexistance Field DRX Config_2 may be included in the DRX configuration information. That is, if the first DRX Config field is included in the DRX configuration information, the information generator 862 can not include the second DRX Config field in the DRX configuration information. Also, if the information generator 862 includes the second DRX Config field in the DRX configuration information, the information generator 862 can not include the first DRX Config field in the DRX configuration information. For example, the first DRX Config field indicates a DRX config corresponding to release version 8 in the LTE system and the second DRX Config field indicates a DRX config corresponding to the release version 11 in the LTE system . In the case where only the first DRX-config is used for the non-IDC irrespective of the release version, the conditional presence for the first DRX-config can be similarly defined. Or DRX_UL-HARQack field may be defined as one of DRX_1 or DRX_2.

The information generating unit 862 may selectively include the DRX_UL-HARQack field in the DRX configuration information only when the first DRX Config field or the second DRX Config field is included in the DRX configuration information. When the determination unit 861 determines to support the power saving operation for the terminal 800, the information generation unit 862 includes the DRX_UL-HARQack field in the DRX configuration information as shown in Table 1 above. On the other hand, if the decision unit 861 decides not to support the power saving operation for the terminal 800, the information generating unit 862 does not include the DRX_UL-HARQack field in Table 1. [

The transmitting unit 855 transmits the DRX configuration information to the terminal 800. The transmitting unit 855 transmits the HARQ ACK for the uplink data received from the terminal 800 to the terminal 800. The present embodiment is characterized in that the transmitting unit 855 transmits to the terminal 800 an uplink grant (including a new data indicator) for receiving the new uplink data by the receiving unit 865, The receiving unit 865 may receive the uplink data from the terminal 800 through the uplink resource. The transmitter 855 may map the HARQ ACK to the PHICH and transmit the HARQ ACK to the terminal 800. The transmission unit 555 can transmit the HARQ ACK only when the retransmission of the corresponding HARQ process is not required to the terminal 800 having the DRX_UL-HARQack structure.

9 is a block diagram illustrating a terminal and a base station according to a second embodiment of the present invention.

9, the terminal 900 includes a receiving unit 905, a terminal processor 910, and a transmitting unit 915. The terminal processor 910 further includes an information generator 911 and an HARQ controller 912.

The information generation unit 911 generates power saving related information. The power saving related information is a basic data used by the base station 950 to determine whether or not to take a power saving operation for the terminal 900. [ The information generation unit 911 can determine the necessity of the power saving operation for the terminal 900 before generating the power saving related information.

As an example, the information generation unit 911 may generate power saving related information including a power priority indicator (PPI) indicating that the configuration optimized for the power saving of the terminal is preferred. The procedure by which the transmitting unit 915 transmits the power priority indicator may be referred to as a terminal auxiliary information transmission procedure. If this procedure is used, the receiver 905 may first receive from the base station 950 a powerPrefIndicationConfig field containing the powerPrefIndicatino-Enabled field. The terminal 900 is allowed to transmit the power priority indicator to the base station 950 through the terminal auxiliary information transmission procedure.

The information generating unit 911 sets the power priority indicator to 'low power consumption', generates the terminal side information including the power priority indicator, and sends the terminal side information to the transmitter 915, May transmit terminal assistance information to the base station (950).

As another example, the information generation unit 911 may generate power saving related information including signal strength information regarding the serving cell of the terminal 900. [ Here, at least one of the reference signal band reception signal RSRP, the reference signal band reception quality RSRQ, and the S-measure may be used as the signal strength information regarding the serving cell of the terminal 900.

The reference value of the S-measure is one of the main configuration information (or indicators) that can measure the radio link performance between the serving cell and the UE 900. For example, if the signal strength information of the serving cell is equal to or greater than the reference value of the S-measure, the information generator 911 does not perform the signal strength measurement operation for the neighboring cell. On the other hand, if the signal strength information of the serving cell is less than or equal to the reference value of the S-measure, the information generation unit 911 performs the signal strength measurement operation for the neighboring cell. When the information generating unit 911 generates the power saving related information as the power saving related information and sends the result to the transmitting unit 915, the transmitting unit 915 transmits the power saving related information to the base station 950.

As another example, the information generating unit 911 may generate power saving related information whose transmission is triggered based on the RRM measurement report event. For example, when a specific RRM measurement report event (for example, event 1A) is set for judging radio link performance deterioration and the event is triggered, the information generation unit 911 generates a measurement report as power saving related information, Unit 915, the transmitting unit 915 transmits power saving related information to the base station 950.

The receiving unit 905 receives uplink shared channel configuration information including a maxHARQ-Tx field set to 'infinity' from the base station 950. A field indicating that the power saving operation is supported may be indicated by the HARQ maximum retransmission count (maxHARQ-Tx) field. The uplink shared channel configuration information (ul-SCH-Config) including the maxHARQ-Tx field set to 'infinity' may be defined as shown in Table 2, for example.

The information generating unit 911 configures maxHARQ-Tx when confirming that the maxHARQ-Tx field set to 'infinity' is present in the UL common channel configuration information. The configuration of maxHARQ-Tx is performed at the level of the RRC layer of the UE 900 and can be completed using the RRC connection reconfiguration procedure. For example, the uplink shared channel configuration information is included in the RRC connection reconfiguration message and is received by the reception unit 905, and the maxHARQ-Tx configuration corresponds to the RRC connection reconfiguration of the information generation unit 911.

The transmitting unit 915 transmits the uplink data to the base station 950 and the receiving unit 905 receives the HARQ ACK for the uplink data from the base station 950. The receiving unit 905 receives from the base station 950 an uplink grant (including a new data indicator) for transmitting new uplink data to the base station 950 and the transmitting unit 915 transmits the uplink grant And transmitting the uplink data to the base station 950 using the uplink resources allocated by the uplink resources.

When the HARQ ACK is received by the receiver 905 in the state in which maxHARQ-Tx is configured, the HARQ controller 912 performs a power saving operation. That is, the power saving operation is performed on condition that maxHARQ-Tx is configured in the UE 900 and that the receiving unit 905 receives HARQ ACK alone for the uplink HARQ data from the Node B 950. Receiving only the HARQ ACK may mean that the receiving unit 905 receives only the HARQ ACK without receiving the UL grant.

Specifically, the power saving operation can be defined as the following operation.

As an example, the power saving operation includes a process of flushing the HARQ buffer in which the HARQ controller 912 stores the uplink data. The HARQ buffer is managed by the MAC layer of the UE 900. Accordingly, when the MAC layer receives the HARQ ACK and confirms that maxHARQ-Tx is configured in the RRC layer, the HARQ controller 912 can flush the HARQ buffer.

Flushing the HARQ buffer affects the DRX operation. This is because the activity time in the DRX operation is i) the time during which the DRX related timer (persistent interval timer, DRX inactivity timer, DRX retransmission timer or MAC contention resolution timer) is in progress, ii) the scheduling request is transmitted on the PUCCH, , And iii) an uplink grant for pending HARQ retransmission may occur and the time at which data in the corresponding HARQ buffer is present may be defined. iii) When the HARQ control unit 912 flushes the HARQ buffer with respect to the active time of the condition, the data is no longer present in the HARQ buffer. Therefore, unless the other conditions are satisfied, . That is, the activity time of the terminal 900 is terminated. From this point of view, the power saving operation may mean that the HARQ control unit 912 ends the active time.

If the receiver 905 determines that maxHARQ-Tx does not exist in the received uplink shared channel configuration information, the HARQ controller 912 performs a DRX operation according to the existing DRX configuration and does not change its activity time . Accordingly, even if the HARQ controller 912 receives the HARQ ACK, the HARQ controller 912 keeps the previous uplink data in the HARQ buffer without flushing the HARQ buffer, and does not perform a separate power saving operation. That is, since the activity time in the DRX is not terminated, the HARQ controller 912 continuously monitors the PDCCH.

The base station 950 includes a transmitting unit 955, a base station processor 960 and a receiving unit 965. The base station processor 960 again includes an information generating unit 962 and a determining unit 961.

The receiving unit 965 receives power saving related information from the terminal 900. The power saving related information is a basic data used by the determination unit 961 to determine whether or not the terminal 900 should perform a power saving operation.

As an example, the power saving related information may include a power priority indicator (PPI) indicating that the terminal 900 prefers a configuration optimized for power saving. In this case, a procedure may be used in which the receiver 965 receives the power priority indicator, which procedure may be referred to as a terminal ancillary information transmission procedure. When this procedure is used, the present embodiment generates a powerPrefIndicationConfig field including the powerPrefIndicatino-Enabled field, and the transmitting unit 955 transmits the powerPrefIndicationConfig field to the terminal 900 .

As another example, the power saving related information may include signal strength information regarding the serving cell of the terminal 900. Here, at least one of the reference signal band reception signal RSRP, the reference signal band reception quality RSRQ, and the S-measure may be used as the signal strength information regarding the serving cell of the terminal 900.

As another example, the power saving related information may be that the transmission is triggered based on the RRM measurement report event. For example, when a specific RRM measurement report event (e.g., event 1A) is set for the determination of radio link performance deterioration and the event is triggered, the receiver 965 also sends a measurement report to the terminal 900 as power- Lt; / RTI >

The determination unit 961 determines whether to support a power saving operation for the terminal 900 based on the power saving related information. As an example, the determination unit 961 can determine whether or not to support the power saving operation for the terminal 900 that has transmitted the power priority indicator set to the low power consumption as the power saving related information. As another example, the determination unit 961 may determine not only the power priority indicator, but also whether or not the power saving operation for the terminal 900 is supported by considering the signal strength for the serving cell described above. For example, for a terminal 900 having a sufficiently strong signal strength for a serving cell, the determination unit 961 can determine to support a power saving operation. As another example, if the determination unit 961 determines that the radio link performance between the terminal and the base station is deteriorated in the future, the determination unit 961 may determine that the terminal 900 supports the power saving operation . For example, when the signal strength information of the serving cell has a value lower than the S-measure reference value or a measurement report based on the RRM measurement report event set for the radio link performance deterioration determination is received from the terminal 900, 900), the determination unit 961 can determine to support the power saving operation.

If the decision unit 961 decides to support the power saving operation for the terminal 900, the information generating unit 962 generates uplink common channel configuration information including a field indicating that the power saving operation is supported . Here, a field indicating that the power saving operation is supported may be denoted by a maxHARQ-Tx field. The information generation unit 962 may set the value of the maxHARQ-Tx field to 'infinity' so that the terminal 900 ends the activity time when receiving the HARQ ACK for the uplink transmission. Uplink common channel configuration information (ul-SCH-Config) including a maxHARQ-Tx field set to 'infinity' may be defined as shown in Table 2, for example.

The possible values for the maxHARQ-TX field are n1, n2, ... , n24, n28, infinity, and spare1. In the present embodiment, a value indicating that the power saving operation is supported through the maxHARQ-Tx field is expressed as infinity. However, the present invention is not limited to this and can be expressed in other terms. Is included in the technical idea of the present invention.

The information generation unit 962 generates uplink shared channel configuration information including a maxHARQ-Tx field set to 'infinity' and sends the uplink shared channel configuration information to the transmission unit 955.

The transmitter unit 955 transmits uplink shared channel configuration information including the maxHARQ-Tx field set to 'infinity' to the terminal 900. The transmitting unit 955 transmits the HARQ ACK for the uplink data received from the terminal 900 to the terminal 900. The present embodiment is characterized in that the transmitting unit 955 transmits to the terminal 900 an uplink grant (including a new data indicator) for receiving the new uplink data by the receiving unit 965, The receiving unit 965 may receive the uplink data from the terminal 900 through the uplink resource. The transmitter 955 may map the HARQ ACK to the PHICH and transmit the HARQ ACK to the terminal 900.

10 is an explanatory diagram illustrating a DRX-based power saving operation according to an embodiment of the present invention.

Referring to FIG. 10, DRX configuration information or uplink shared channel configuration information is signaled from a base station to a mobile station (S1000). At this time, the DRX configuration information includes a DRX_UL-HARQack field for supporting a DRX-based power saving operation of the UE. The UE configures DRX_UL-HARQack. This is shown in Table 1, for example. Or uplink common channel configuration information includes a maxHARQ-Tx field set to 'infinity' to support DRX-based power saving operations. This is shown in Table 2, for example.

A wireless communication system transmits and receives data based on a structure of a frame on a time axis, and one frame includes 10 subframes. One subframe may be referred to as a transmission time interval (TTI) and may have a length of 1 ms.

The HARQ operation basically transmits or retransmits data on a per HARQ process basis. For example, assuming that there are eight HARQ processes in total, HARQ process # 1 includes subframe 0 and subframe 8 of frame 0, subframe 6 of frame 1, subframe 4 of frame 2, ... (Data reception or transmission) at 8 subframe periods. That is, the subframes allocated for each HARQ process number to process data are different.

For example, in HARQ process # 6, a PDCCH to which an uplink grant (UL grant) is mapped in subframe 5 of frame 0 is transmitted from the BS to the UE is processed by HARQ process # 6 (S1005). In this case, since the UE must receive the PDCCH in terms of DRX operation, it must enter the active time. The UE transmits uplink data to the Node B using uplink resources indicated by the uplink grant (S1010). At this time, the uplink data transmission timing is 4ms (or 4 subframes) after the PDCCH received subframe . That is, in the subframe 9 of frame 0, the UE can transmit UL data to the BS.

Since subframe 3 of frame 1, which is 8 subframes after the PDCCH is received, is allocated to HARQ process # 6, HARQ process # 6 signals the HARQ ACK to the UE from the BS (S1015) . In subframe 3 of frame 1, the terminal must be in active time to receive the HARQ ACK. Therefore, at this point in time, the DRX operation of the terminal enters the active time. However, since the UE has configured the maxHARQ-Tx set to 'DRX_UL-HARQack' or 'infinity' and has also received the HARQ ACK, the UE flushes the HARQ buffer and ends the active time (S1020).

Therefore, even if subframe 1 of frame 2 in which HARQ process # 6 processes data after 8 subframes (SF) arrives, the UE does not enter the active time. Since the base station does not transmit the HARQ ACK / NACK in the subframe 1 of the frame 2 anyway, the terminal does not need to perform unnecessary PDCCH monitoring.

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

Claims (20)

A method of performing a power saving operation of a terminal based on discontinuous reception (DRX)
Transmitting power saving related information to a base station; And
DRX configuration information including a DRX_UL-HARQack field supporting a DRX-based power saving operation to the UE from the BS,
The power-
And flushing the HARQ buffer storing the uplink data when the DRX_UL-HARQack is configured in the UE and the HARQ ACK for the uplink data alone is received from the base station. Gt; to < / RTI > the power saving operation. The method according to claim 1,
Wherein the power saving related information includes a power priority indicator (PPI) indicating that the terminal prefers configuration optimized for power saving. . The method according to claim 1,
Wherein the power saving related information includes signal strength information regarding a serving cell of the UE. The method according to claim 1,
The DRX_UL-HARQack field includes a first DRX Config field for defining DRX operation parameters related to the UE and a second DRX Config field for defining DRX operation parameters according to an interdevice coexistance (IDC) Lt; RTI ID = 0.0 > DRX < / RTI > configuration information. The method according to claim 1,
The power-
Further comprising the step of terminating the active time of the DRX. A terminal for performing DRX-based power saving operation,
An information generating unit for generating power saving related information;
A transmission unit for transmitting the power saving related information to the base station;
A receiving unit for receiving DRX configuration information including a DRX_UL-HARQack field supporting a DRX-based power saving operation to the UE from the BS; And
And an HARQ control unit for performing the power saving operation,
The power-
The HARQ controller may flush the HARQ buffer storing the uplink data if the DRX_UL-HARQack is configured in the UE and the HARQ ACK for the uplink data is received from the BS. . ≪ / RTI > The method according to claim 6,
Wherein the transmission unit transmits the power saving related information including the power priority indicator (PPI) indicating that the UE prefers a configuration optimized for power saving to the base station. The method according to claim 6,
Wherein the transmitting unit transmits the power saving related information including signal strength information on a serving cell of the UE to the base station. The method according to claim 6,
The DRX_UL-HARQack field includes a first DRX Config field for defining DRX operation parameters related to the UE and a second DRX Config field for defining DRX operation parameters according to an interdevice coexistance (IDC) Wherein the DRX configuration information can be selectively included in the DRX configuration information only when included in the information. 7. The method of claim 6,
Further comprising terminating the DRX activity time. A method for performing a power saving operation of a terminal based on DRX by a base station,
Receiving power saving related information from the terminal;
Determining whether to support a power saving operation for the terminal based on the power saving related information; And
And DRX configuration information including a DRX_UL-HARQack field supporting the power saving operation based on the DRX to the UE, to the UE,
The power-
When the DRX_UL-HARQack is configured in the UE and the UE receives from the Node B an HARQ ACK for uplink data, the UE flushes the HARQ buffer storing the uplink data ≪ / RTI > wherein the method further comprises: 12. The method of claim 11,
Wherein the power saving related information includes a power priority indicator (PPI) indicating that the terminal prefers an optimized configuration for power saving. 12. The method of claim 11,
Wherein the power saving related information includes signal strength information regarding a serving cell of the UE. 12. The method of claim 11,
The DRX_UL-HARQack field includes a first DRX Config field for defining DRX operation parameters related to the UE and a second DRX Config field for defining DRX operation parameters according to IDCs in the DRX configuration information ≪ RTI ID = 0.0 > and / or < / RTI > the DRX configuration information. 12. The method of claim 11,
The power-
Further comprising terminating the DRX activity time. ≪ RTI ID = 0.0 > 31. < / RTI > A base station for performing a power saving operation of a DRX-based terminal,
A receiving unit for receiving power saving related information from the terminal;
A determination unit for determining whether to support a power saving operation for the terminal based on the power saving related information;
An information generating unit for generating DRX configuration information including a DRX_UL-HARQack field for supporting the power saving operation based on the DRX to the UE; And
And a transmitter for transmitting the HARQ ACK for the DRX configuration information and the uplink data to the UE,
The power-
When the DRX_UL-HARQack is configured in the UE and the UE receives from the Node B an HARQ ACK for uplink data, the UE flushes the HARQ buffer storing the uplink data And a base station. 17. The apparatus of claim 16,
And the power saving related information including a power priority indicator (PPI) indicating that the terminal prefers a configuration optimized for power saving. 17. The apparatus of claim 16,
Related information including signal strength information about a serving cell of the terminal. The information processing apparatus according to claim 16,
Only when DRX configuration information includes a first DRX Config field defining DRX operation parameters related to the UE and a second DRX Config field defining DRX operation parameters according to IDCs, And selectively includes the DRX_UL-HARQack field in the configuration information. 17. The method of claim 16,
The power-
And terminating the DRX activity time.

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