WO2013168891A1

WO2013168891A1 - Method and device for reconfiguring drx by considering packet inter arrival time

Info

Publication number: WO2013168891A1
Application number: PCT/KR2013/002198
Authority: WO
Inventors: 정명철; 권기범; 안재현; 허강석
Original assignee: 주식회사 팬택
Priority date: 2012-05-11
Filing date: 2013-03-18
Publication date: 2013-11-14
Also published as: KR20130126403A

Abstract

The present invention relates to a wireless communication system, and more specifically, to a method and a device for reconfiguring DRX by considering packet inter arrival time (IAT), and comprising the steps of: calculating a packet IAT; transmitting the packet IAT to a base station; receiving from the base station DRX reconfiguration information which is modified on the basis of the packet IAT; and reconfiguring the DRX on the basis of the DRX reconfiguration information that is received, thereby enabling a terminal to efficiently carry out a DRX action and saving power of the terminal.

Description

Reconstruction method and apparatus for drＸ considering packet arrival interval

The present invention relates to a wireless communication system, and more particularly, to a DRX reconfiguration method and apparatus in consideration of an inter arrival time of a packet in a wireless communication system.

Due to the popularization of various mobile devices such as smartphones or tablets, various kinds of applications are used. As a result, various applications generate traffic to a wireless network rather than to a wired one. However, a wireless network such as LTE is designed without considering various kinds of traffic occurrence situations caused by application use in various mobile devices.

Since the battery of the terminal is limited, power saving should be considered as much as possible. The terminal may use a DRX scheme for power saving. The DRX method is a method in which the UE saves power by periodically changing the active time and the inactive time. The activity time is a period in which the terminal wakes up to receive the PDCCH. Inactivity time is a period in which the UE sleeps without receiving the PDCCH. The DRX method may use two modes, a long DRX mode and a short DRX mode, but the existing DRX method is limited and unnecessary to operate without considering various traffic patterns. There is a problem that can consume power.

On the other hand, among the traffic generated in the wireless network, the traffic types mainly considered for power saving, etc. include IM (Instant Messanger) and BG (Background) traffic. IM is traffic used in an application that provides an interactive service such as MSN messenger, KakaoTalk, and the like, and includes an instant message and IM background traffic. BG traffic is traffic that may be generated to maintain a state in an OS (Operation System) even when the UE does not operate in an actual active phase. Such traffic can be generated and transmitted periodically with a relatively small packet size.

An object of the present invention is to provide a method and apparatus for performing DRX reconfiguration in a wireless communication system.

Another technical problem of the present invention is to provide a method and apparatus for performing DRX reconstruction based on an inter-arrival time (IAT).

Another technical problem of the present invention is to provide a method and apparatus for providing information on a packet arrival interval.

Another technical problem of the present invention is to provide a method and apparatus for providing DRX reconfiguration information considering a packet arrival interval.

According to an aspect of the present invention, a terminal for performing a discontinuous reception (DRX) operation in consideration of an inter-arrival time of a packet in a wireless communication system is provided. The terminal includes an IAT processing unit for calculating a packet IAT, a transmitting unit for transmitting the packet IAT to a base station, a receiving unit for receiving modified DRX reconfiguration information based on the packet IAT from the base station, and the received DRX reconfiguration information. It includes a DRX processing unit for performing a DRX reconfiguration based on.

According to another aspect of the present invention, there is provided a base station for controlling a DRX operation of a terminal considering the arrival interval (IAT) of a packet in a wireless communication system. The base station includes a receiver for receiving a packet IAT from the terminal, a DRX processor for modifying a DRX related parameter based on the received packet IAT, and DRX reconfiguration information including the changed DRX related parameter. It includes a transmission unit for transmitting to.

According to still another aspect of the present invention, there is provided a DRX method considering a packet arrival interval by a terminal in a wireless communication system. The method includes calculating a packet IAT, transmitting the packet IAT to a base station, receiving modified DRX reconfiguration information from the base station based on the packet IAT, and based on the received DRX reconfiguration information. Performing a DRX reconfiguration.

According to still another aspect of the present invention, there is provided a method of controlling a DRX operation of a terminal in consideration of a packet arrival interval by a base station in a wireless communication system. The method includes receiving a packet IAT from the terminal, performing a modification of a DRX related parameter based on the received packet IAT, and sending DRX reconfiguration information including the changed DRX related parameter to the terminal. Transmitting.

According to the present invention, by reconfiguring the DRX based on the packet arrival interval, it is possible to perform more efficient DRX operation than the general DRX method.

According to the present invention, an efficient DRX operation may be performed to save power of a terminal.

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

2 shows a structure of a subframe to which the present invention is applied.

3 is an explanatory diagram for explaining a DRX operation to which the present invention is applied.

4 illustrates an EPS bearer (Evolved Packet System Bearer) to which the present invention is applied.

5 shows a structure of a radio bearer (RB) connecting a terminal and a base station.

6 shows an SDU and a PDU generation process in a protocol.

7 is a flowchart illustrating a method of transmitting packet IAT information according to an embodiment of the present invention.

8 illustrates a case in which a packet is generated and transmitted with a periodicity according to an embodiment of the present invention.

9 illustrates a DRX operation of a terminal according to an embodiment of the present invention.

10 illustrates a DRX operation of a terminal considering a packet IAT according to an embodiment of the present invention.

11 illustrates a DRX operation of a terminal considering packet IAT according to another embodiment of the present invention.

12 illustrates a DRX operation of a terminal considering a packet IAT according to another embodiment of the present invention.

13 illustrates a DRX operation of a terminal in consideration of a packet IAT according to another embodiment of the present invention.

14 is a flowchart illustrating an operation of a terminal performing a DRX operation in consideration of a packet IAT according to an embodiment of the present invention.

15 is a flowchart illustrating an operation of a base station performing a DRX operation in consideration of a packet IAT according to an embodiment of the present invention.

16 is a block diagram illustrating a terminal and a base station performing a DRX operation in consideration of a packet IAT according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to the accompanying drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in the following description of the embodiments of the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the subject matter of the present specification, the detailed description thereof will be omitted.

In addition, the present specification describes a wireless communication network, the operation performed in the wireless communication network is performed in the process of controlling the network and transmitting data in the system (for example, the base station) that is in charge of the wireless communication network, or the corresponding wireless Work may be done at the terminal coupled to the network.

Referring to FIG. 1, the wireless communication system 10 is widely deployed to provide various communication services such as voice and packet data. The wireless communication system 10 includes at least one base station (BS) 11. Each base station 11 provides a communication service for

specific cells

15a, 15b, and 15c. The cell can in turn be divided into a number of regions (called sectors). The base station 11 may be called in other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, an femto base station, a home nodeB, a relay, and the like. . A cell is meant to encompass all of the various coverage areas such as megacell, macrocell, microcell, picocell, femtocell, and the like.

The UE 12 may be fixed or mobile and may have a mobile station (MS), a mobile terminal (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, or a PDA. (personal digital assistant), wireless modem (wireless modem), a handheld device (handheld device) may be called other terms.

Hereinafter, downlink refers to a transmission link from the base station 11 to the terminal 12, and uplink refers to a transmission link from the terminal 12 to the base station 11. it means. In downlink, the transmitter may be part of the base station 11 and the receiver may be part of the terminal 12. In uplink, the transmitter may be part of the terminal 12 and the receiver may be part of the base station 11. There is no limitation on the multiple access scheme applied to the wireless communication system. Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA (SC-FDMA), OFDM-FDMA, OFDM-TDMA For example, various multiple access schemes such as OFDM-CDMA may be used. The uplink transmission and the downlink transmission may use a time division duplex (TDD) scheme that is transmitted using different times, or may use a frequency division duplex (FDD) scheme that is transmitted using different frequencies.

2 shows a structure of a subframe to which the present invention is applied.

Referring to FIG. 2, one radio frame includes 10 subframes, and one subframe includes two consecutive slots. The preceding 1, 2, 3 or 4 OFDM symbols of the first slot in the subframe are the control channel region to which the PDCCH is mapped, and the remaining OFDM symbols are the physical downlink shared channel (PDSCH). This is the data channel region to be mapped. The control channel region may be called a control region, and the data channel region may be called a data region. In addition to the PDCCH, a control channel such as PCFICH and PHICH may be allocated to the control channel region.

The terminal uses the cell-radio network temporary identifier (C-RNTI), transmission power control (TPC) -PUCCH-RNTI, TPC-PUSCH-RNTI, and semi persistent scheduling (SPS) -RNTI, Monitoring can be performed. Monitoring of the PDCCH can be controlled by the DRX (Discontinuous Reception) operation, the parameter about the DRX is transmitted by the base station to the terminal by the RRC message. In addition to the RNTIs, the UE should always receive system information (RN) -RNTI, p (paging) -RNTI, etc. regardless of the DRX operation configured by the RRC message. Here, the remaining PDCCHs except the PDCCH scrambled with C-RNTI are always received through a common search space of the main serving cell.

If the terminal has a DRX parameter configured in the RRC connected state, the terminal performs discontinuous monitoring on the PDCCH based on the DRX operation. On the other hand, if the DRX parameter is not configured, the UE monitors the continuous PDCCH. Discontinuous PDCCH monitoring may mean that the UE monitors the PDCCH only in a specific subframe, and continuous PDCCH monitoring may mean that the UE monitors the PDCCH in all subframes. On the other hand, if PDCCH monitoring is required in a DRX independent operation such as a random access procedure, the UE monitors the PDCCH according to the requirements of the corresponding operation.

In other words, DRX allows a UE to stop monitoring a packet data control channel (PDCCH) for a period of time (ie, a sleep period or an inactive time). The UE repeats a wake up or active and sleep or non-active or inactive period in the DRX mode. Wake up (or activity) means monitoring the packet data control channel (PDCCH). Sleep (or inactivity) means stopping monitoring the Packet Data Control Channel (PDCCH).

The DRX may be configured by radio resource control / media access control (RRC / MAC). Related DRX parameters may include a long DRX cycle, a DRX Inactivity Timer, and a DRX Retransmission Timer. Also optionally, the DRX includes a short DRX cycle and a DRX Short Cycle Timer (drxShortCycleTimer). The long term DRX cycle provides a longer sleep period for the terminal than the short term DRX cycle.

Referring to FIG. 3, the DRX operation is repeated in units of DRX cycles 300, and the DRX cycle 300 is a periodic repetition of a DRX opportunity (DRX opportunity 310) and a duration (On Duration 305). Is defined. One cycle of DRX cycle 300 includes a duration 305 and a DRX opportunity (310). The DRX cycle 300 includes, for example, a long DRX cycle applied in a range between 10 subframes and 2560 subframes, and in another example, a short DRX cycle applied in a range of 2 subframes to 640 subframes. DRX cycle). At this time, the short term DRX cycle is applied only while the DRX short cycle timer (drxShortCycleTimer) is operating, and the long term DRX cycle is applied outside the range in which the DRX short cycle timer is operated. Here, in the DRX short cycle timer, one short DRX cycle becomes a basic unit. At this time, the length of the short-term DRX cycle timer may be 1 to 16, for example. When the terminal is operating in the short-term DRX cycle may be referred to as a short-term DRX mode, when the terminal is operating in the long-term DRX cycle.

The RRC layer manages several timers to control the DRX operation. Timers controlling the DRX operation include a duration timer (onDurationTimer), a DRX inactivity timer (DRxInactivity Timer), a DRX retransmission timer (drxRetransmission Timer).

The duration timer is started by the start of the DRX cycle. In other words, the start of the duration timer coincides with the start of the DRX cycle. The duration timer increases by 1 for every PDCCH subframe. The duration timer expires when the duration timer value becomes equal to a preset expiration value. The duration timer is valid until the duration timer value is equal to the expiration value.

The DRX inactivity timer may be defined as the number of consecutive PDCCH subframes from the time point of successfully decoding the PDCCH for uplink or downlink user data transmission. Since continuous data reception may occur, it is time for the UE to continuously monitor the PDCCH. The DRX Inactivity Timer is started or restarted when the UE successfully decodes the PDCCH for HARQ initial transmission in the PDCCH subframe.

The DRX retransmission timer is a timer that operates based on the maximum number of consecutive numbers of PDCCH subframes for which downlink retransmission is expected by the terminal soon. The DRX retransmission timer is a timer that is started when the retransmission data is not received even though the HARQ RTT timer has expired. The terminal may monitor the reception of data retransmitted in the HARQ process while the DRX retransmission timer is in progress. The setting of the DRX retransmission timer is defined by the MAC-MainConfig message of the RRC layer.

The time that the duration timer, the DRX inactivity timer, or the DRX retransmission timer is in progress is called an active time. Alternatively, the activity time may mean all sections in which the terminal is awake. Non-active time during the DRX cycle may be referred to as non-active time. The active time may be called a wake up interval, and the inactive time may be called a sleep interval. The UE monitors the PDCCH for the PDCCH subframe during the active time. Here, the PDCCH subframe means a subframe including the PDCCH. For example, in TDD configuration, downlink subframes and downlink pilot time slot (DwPTS) subframes correspond to PDCCH subframes. A timer unit of a DRX timer, such as a duration timer, a DRX inactivity timer, or a DRX retransmission timer, is a PDCCH subframe (psf). That is, DRX timers are counted based on the number of PDCCH subframes.

Other parameters to control DRX operation include long DRX cycle (longDRX-Cycle) and DRX start offset (drxStartOffset) .The base station can optionally set DRX short cycle timer (drxShortCycleTimer) and short DRX-cycle (shortDRX-Cycle). Can be. In addition, a HARQ round trip time (RTT) timer is defined for each downlink HARQ process.

The DRX start offset is a value that defines the subframe where the DRX cycle 300 begins. The DRX short cycle timer is a timer that defines the number of consecutive subframes that the UE should follow the short DRX cycle. The HARQ RTT timer is a timer that defines the minimum number of subframes before the interval in which downlink HARQ retransmission is expected by the UE.

Meanwhile, the DRX configuration information may be received by being included in a MAC-MainConfig message, which is an RRC message used to specify a main configuration of a MAC layer for a signaling radio bearer (SRB) and a data radio bearer (DRB). DRX configuration information may be configured, for example, as shown in the table below.

Table 1

Referring to Table 1, the DRX configuration information includes a longDRX-CycleStartOffset field indicating a length of a long DRX cycle and a starting subframe, and a shortDRX field regarding a short DRX that may be configured as optional. The shortDRX field specifically includes a shortDRX-Cycle subfield indicating the length of a short DRX cycle and a drxShortCycleTimer subfield indicating a value of a short term DRX cycle timer in which the UE is continuous.

The longDRX-CycleStartOffset field may be set to any one of values of {sf10, sf20, sf32, sf40, ... sf2560} as the length of a long DRX cycle, and the subframe where the long DRX cycle starts is the length of the long DRX cycle. The value may be set to any one of {INTEGER (0..9), INTEGER (0..19), INTEGER (0..31), ... INTEGER (0..2559)}. For example, if the longDRX-CycleStartOffset field = sf20, INTEGER (0..19), one long DRX cycle includes 20 subframes, and the long DRX cycle includes any subframe of subframe indexes 0 to 19. This long term DRX cycle start subframe may be selected. The shortDRX-Cycle subfield constituting the shortDRX field may be set to any one of {sf2, sf5, sf8, ... sf640}. For example, if the shortDRX-Cycle subfield = sf5, one short DRX cycle includes 5 subframes. In addition, the drxShortCycleTimer subfield constituting the shortDRX field may indicate any one of integers 1 to 16. For example, if the drxShortCycleTimer subfield = 3, the short DRX cycle has gone through three times and then expires.

In some cases, when the packet is transmitted in a form in which the generation interval of the packet is constant or gathered at a predetermined interval, the traffic may be periodic. Inter-Arrival Time (IAT) may be defined as an interval in which the terminal generates an uplink packet or an interval in which a downlink packet is received. Alternatively, the arrival interval (IAT) may be defined as an interval at which the base station receives an uplink packet or an interval for generating a downlink packet. As an example of periodic traffic, IM or BG traffic may be applied. IM is traffic used in an application that provides an interactive service such as MSN messenger, KakaoTalk, and the like, and includes an instant message and IM background traffic. BG traffic is traffic that may be generated to maintain a state in an OS (Operation System) even when the UE does not operate in an actual active phase.

In the DRX operation, DRX reconfiguration may be performed in consideration of the arrival interval IAT of the packet as described above. For example, the terminal may change the DRX mode to the short term DRX mode or the long term DRX mode in consideration of the IAT of the packet, or may change the DRX cycle. This can increase the efficiency of DRX operation. In order to perform the above operation, the terminal or the base station needs to secure the IAT of the packet. There may be various methods for obtaining an IAT of a packet. For example, the packet may be obtained based on the following criteria.

Referring to FIG. 4, when a terminal 400 accesses a wireless communication network (eg, an LTE network), an EPS bearer is generated from the terminal to the PDN-GW 460. Here, the EPS bearer is a transmission path generated between the UE 400 and the PDN-GW 460, and various types of traffic may pass through the EPS bearer. The various kinds of traffic may be called an IP flow, and the IP flow may be a source IP, a destination IP, a protocol ID, a source port of a packet. It may be divided into a destination port.

One or more EPS bearers may be generated per terminal. EPS bearer is composed of a radio bearer (RB, 410), S1 bearer 430, S5 / S8 bearer 450, etc., it can be seen that the traffic flow (traffic flow) for each EPS bearer.

In more detail, the terminal 400 is connected to the base station 420 through the radio bearer 410. The base station 420 is connected to a Serving Gateway (S-GW) through the S1 bearer 430. The S-GW is connected to the PDN-GW (Packet Data Network Gateway) 460 through the S5 / S8 bearer 450.

Looking at the traffic flow in the uplink (UL) direction, the terminal 400 determines which EPS bearer to send the packet through the UL TFT (Traffic Flow Template). The UL TFT is received from the network while the terminal is connected to the network. When determining which EPS bearer to send through, the terminal 400 transmits an RB-ID value to the packet to the base station 420 through the radio bearer 410. The base station 420 determines the destination S-GW 440 and the S1 Tunnel Endpoing Identifier (TE1) value based on the RB-ID value, and loads the S1 TEID value in the received packet to load the S1 bearer 430. Transmit to S-GW (440). The S-GW 440 determines the destination PDN-GW 460 and the S5 TEID (or S8 TEID) value based on the S1 TEID value, and loads the S5 TEID (or S8 TEID) on the received packet to S5 /. Transmit to the PDN-GW 460 through the S8 bearer (S440). The PDN-GW 460 may know which UE sent a packet based on the S5 TEID (or S8 TEID).

The traffic flow in the downlink (DL) direction may be the inverse of the traffic flow in the uplink direction described above.

In a wireless communication system, for example, an LTE system, a packet flow exists on an EPS bearer, and one EPS bearer corresponds to one radio bearer 410, an S1 bearer 430, and an S5 / S8 bearer 450, respectively. . Accordingly, packet traffic transmitted and received on one EPS bearer may be viewed as being managed in units of radio bearers 410 on the radio side.

5 shows a structure of a radio bearer (RB) connecting a terminal and a base station. There may be more than one radio bearer for one terminal. Although FIG. 5 illustrates three radio bearers, more or less radio bearers may be configured.

Referring to FIG. 5, a radio bearer 500 exists between a terminal and a base station, and one radio bearer 500 has a one-to-one matching relationship with one S1 bearer 550. One radio bearer 500 is implemented in a form that exists on the Protocol Data Convergence Protocol (PDCP), Radio Link Control (RLC), Medium Access Control (MAC), and Physical (PHY) of the base station and the terminal. In other words, one radio bearer 500 includes a pair of PDCP, RLC, MAC, and PHY entities. There may be a plurality of radio bearers 500 in one terminal.

6 illustrates a process of generating an SDU and a PDU in a protocol. 6 assumes that there is no fragmentation or concentration.

Referring to FIG. 6, the Packet Data Convergence Protocol (PDCP) 600 is responsible for delivering user data, header compression, and ciphering. The PDCP 600 may be viewed as a boundary for sending and receiving packet traffic to the radio bearer and the S1 bearer. Therefore, the start of the radio section in which specific application packet traffic is transmitted and received can be regarded as PDCP (600). At this time, the PDCP generates a received packet as a PDCP SDU (Sevice Data Unit), and attaches a PDCP header to the PDCP SDU to generate a PDCP PDU (Protocol Data Unit). The PDCP PDU becomes an RLC SDU in the RLC 620 layer.

The RLC 620 receives a PDCP PDU (RLC SDU) delivered from the PDCP 600, performs fragmentation or concatenation, and prepares for radio link transmission. At this time, the RLC 620 may change the size by dividing or concatenating the RLC SDU according to the radio situation. For example, when a situation in which the size of an RLC SDU is larger than a size that can be sent at a time in a wireless situation occurs, the RLC SDU may be divided into appropriate sizes, and the cut portion may be connected to another RLC SDU. The RLC 620 generates an RLC PDU by attaching an RLC header to the RLC SDU.

The MAC 640 is responsible for logical channel multiplexing, HARQ retransmission, and uplink / downlink scheduling. The MAC 640 may multiplex or demultiplex the RLC PDUs (MAC SDUs) transmitted from the RLC 620 between logical channels and transport channels. The MAC 640 generates a MAC PDU by attaching a MAC header to the MAC SDU.

The PHY 660 is responsible for coding, physical layer HARQ processing, modulation, multi-antenna processing, and mapping signals to appropriate physical time-frequency resources. The PHY 660 also performs mapping of transport channels to physical channels. The PHY 660 may transmit MAC PDUs (PHY SDUs or Transport Blocks (TBs)) according to the actual radio duration.

The packet entering the PDCP 600 is transmitted after completing the operation in the corresponding protocol via the RLC 620, MAC 640, PHY 660. Transmission data scheduling in subframe units is performed in the MAC, and the DRX operation is also performed in subframe units as described above. The transport block generated in the MAC is transmitted according to the HARQ operation in the radio section via the PHY 660.

Although processing delays may occur until packets entering PDCP 600 are delivered to RLC 620, MAC 640, and PHY 660 in actual operation, the processing delay is negligibly small. Or constant. Accordingly, it is determined that a time point at which a packet is input to the PDCP 600 and a time point at which data is scheduled and allocated to a subframe in the MAC 640 are the same. In this case, the time point at which the packet enters the PDCP and the time point at which the data for the packet is allocated to the subframe can be viewed in the same manner. In other words, it is assumed that the time point at which the packet enters the PDCP 600 through the radio bearer and the time point at which the data for the packet is allocated to the subframe in the MAC 640 are the same. In particular, a packet is not sent. It is considered that the packet is transmitted to the MAC 640 at the time when the packet arrives at the PDCP 600 to schedule data for the packet in a subframe.

Therefore, in this case, the PDCP 600 can be identified as a location for data corresponding to the application, and the timing of packet traffic transmitted and received from the PDCP 600 is defined as the IAT (Inter-Arrival Time) of the packet of the actual application. can do. In this case, the IAT of the packet may be defined by the following criteria.

1. Packet IAT defined from downlink (DL) perspective

In the case of a terminal, when the terminal receives a downlink packet from the network, the terminal may calculate the IAT by tracing the reception timing. In this case, the time point at which the terminal receives the packet may be measured based on the PDCP. For example, the terminal may check the time point when the PDCP SDU or the PDCP PDU number is increased, and may always check the reception time, and may measure the IAT of the packet based on this.

In the case of a base station (network), when packet traffic is introduced into a radio bearer through a base station (network) S1 bearer, it is possible to confirm when the packet is received by checking when the PDCP SDU or PDCP PDU number generated by the PDCP is increased. We can measure the packet's IAT.

In addition, the mean IAT (Mean IAT) for the actually measured packet arrival time may be calculated and used as the IAT value.

In addition, when there are several EPS bearers instead of one, there may be radio bearers for each EPS bearer, and PDCP for each radio bearer may exist.

Specifically, the IAT value may be calculated in the following manner.

First, individual packet IAT values can be secured by individually using each packet IAT based on the individual PDCP. In this case, one IAT value may exist for each PDCP.

Second, one representative packet IAT may be defined using the average of individual packet IATs for each bearer. In this case, the IAT value does not exist for each PDCP or radio bearer, and only one representative packet IAT value exists.

Third, the PDCP SDU or PDCP PDU number is increased based on one PDCP representing each radio bearer, and may be defined as one packet IAT representing all radio bearers. Here, the method of selecting one PDCP may have various methods. For example, it may be selected based on the PDCP having the smallest IAT value. Alternatively, the selection may be made based on the PDCP having the largest IAT value.

On the other hand, the base station (network) can also check the traffic transmitted from the base station to the terminal to calculate the packet IAT. Uplink traffic is sent to the base station through an S1 bearer, which is in turn mapped to a radio bearer. Therefore, the time point at which the packet is received by the base station through the S1 bearer can be known as the IAT of the packet. Alternatively, the packet IAT may be identified when the packet is mapped to the radio bearer. In this case, the IAT of the packet may be determined based on the PDCP of the base station.

2. Packet IAT Defined from the UL View

The base station or the terminal may calculate the IAT of the packet on the uplink basis. The terminal may check the information on the uplink traffic according to its application situation. In this case, the terminal may maintain the state without using the DRX for the purpose of transmitting a scheduling request (SR) for uplink traffic to be transmitted, and it may be difficult to accurately predict the interval. As a result, it can be difficult to keep track of activity time accurately.

Meanwhile, the packet IAT may be different from the uplink packet IAT and the downlink packet IAT. In this case, the packet IAT can be obtained based on the downlink. Alternatively, the packet IAT may be obtained on an uplink basis. Alternatively, the packet IAT may be determined as one of values related to downlink and uplink. For example, if the downlink packet IAT is 30 ms and the uplink packet IAT is 40 ms, the packet IAT may be set to 30 ms in consideration of the smaller packet IAT. Alternatively, the packet IAT may be set to 40 ms in consideration of the larger packet IAT.

Referring to FIG. 7, the terminal calculates a packet IAT (S700). As described above, the method for calculating the packet IAT may include both a method for calculating a packet IAT defined from a downlink (DL) point of view and a method for calculating a packet IAT defined from an uplink (UL) point of view.

The base station may also calculate the packet IAT as described above, in which case S700 and S710 may be omitted.

The terminal transmits the packet IAT information indicating the calculated packet IAT to the base station (S705). As an example, the packet IAT information may be transmitted through dedicated signaling or a medium access control (MAC) control element (CE) for the terminal. As another example, the packet IAT information may be transmitted as a RRC message through a measurement reporting message or an RRC UE assistance information message. The measurement report is a message in which the terminal reports information about the measurement to the base station. The terminal assistance information message is an auxiliary information message transmitted from the terminal to the base station, and may be information related to a multimedia broadcast multicast system (MBMS), a heterogeneous network (HetNet), and enhancements for diverse data applications (EDDA), and can be identified by the terminal. The calculated value, detection value, or threshold value for all information may be included.

Upon receiving the packet IAT information, the base station reconfigures the DRX related parameter such that the transmission time of the estimated downlink packet based on the packet IAT matches the on duration (S710). As one example, the base station may reconfigure the DRX related parameters to change the short term DRX mode to the long term DRX mode previously. As another example, the base station may reconfigure the DRX related parameters in a manner that previously lengthens or shortens the length of the long term DRX cycle. As another example, the base station may reconfigure the DRX related parameters to maintain the long-term DRX mode so that the long-term DRX mode is not previously switched to the short-term DRX mode.

The base station transmits DRX reconfiguration information to the terminal (S715). The DRX reconfiguration information may be transmitted using an RRC connection reconfiguration message.

Upon receiving the DRX reconfiguration information, the UE reconfigures DRX related parameters (S720). DRX reconfiguration may include an operation to prohibit switching to short-term DRX mode. Or DRX reconstruction may include changing the length of the long term DRX cycle upon switching to long term DRX.

If the UE and the base station know each other by knowing a pattern or a method for reconstructing DRX based on the packet IAT, the UE and the base station may reconfigure DRX related parameters based on the same packet IAT. For example, the base station may reconfigure the DRX related parameters, and the terminal may reconfigure the DRX related parameters by itself without receiving the DRX reconfiguration information from the base station. In this case, step S715 in which the base station transmits DRX reconfiguration information to the terminal may be omitted.

The terminal performs a DRX operation based on the reconfigured DRX related parameters and performs downlink reception or uplink transmission based on an active time (or duration) and packet IAT according to the reconfigured DRX related parameters. . A method of reconstructing a DRX parameter in consideration of a packet IAT and a method of performing a DRX operation by a terminal according to the reconstructed DRX are described below.

8 illustrates a case in which a packet is generated and transmitted with a periodicity according to an embodiment of the present invention. One square represents a subframe. When the index of the first subframe is regarded as 1 and the index of the next subframe is sequentially increased by 1, the subframes 100 through 100 are illustrated. 9 to 13 are also the same below.

Referring to FIG. 8, FIG. 8 illustrates an example in which packet traffic is generated and transmitted with periodicity. As shown in FIGS. 4 to 6, packets arrive based on a packet IAT value calculated based on PDCP. The ideal case is assumed. The subframe in which the packet arrives is the first subframe 800, the 31st subframe 810, the 61st subframe 820, and the 91st subframe 830, as shown. The timing is constant at 30ms intervals.

Specifically, it is assumed that the next packet is generated and transmitted from the base station to the terminal 30 ms after the first packet occurs, and the received packet is accurately scheduled at a corresponding timing and allocated to a subframe of the corresponding timing. In other words, it is assumed that the first packet arriving at the protocol corresponding to the PDCP is allocated to the subframe at the corresponding timing and transmitted. Thus, the packet is transmitted once every three radio frames, that is, 30 subframes.

9 illustrates a DRX operation of a terminal according to an embodiment of the present invention. One square represents a subframe, the colored subframe represents the packet arrival time, and the hatched subframe represents the duration of the DRX cycle.

Referring to FIG. 9, a DRX operation is shown when packet traffic is transmitted with periodicity. The long-term DRX cycle is 20 ms, the on duration is 2 ms, the short-term DRX cycle is 10 ms, and the DRX short cycle timer (drxShortCycleTimer) is 3.

An arrow indicates an operation of receiving a scheduled PDCCH by the terminal upon packet arrival. As described with reference to FIG. 8, a packet may be generated and transmitted in a first subframe, a 31st subframe, a 61st subframe, and a 91st subframe, but in the case of the first packet, a first packet is generated and transmitted. In one subframe, since the UE operates with a non-active time, it cannot receive a packet. Therefore, the terminal receives the first packet in the eleventh subframe instead of the first subframe. Thereafter, the UE repeats the DRX operation by a parameter set in the DRX configuration. The terminal may enter the short-term DRX mode in preparation for additional packet reception after a long-term DRX cycle including a section in which the packet was received upon packet reception. Since it is assumed here that the DRX short cycle timer is 3, the UE will repeat the short-term DRX cycle three times from the 31 st subframe to the 60 th subframe (the first interval, 930) and re-enter the long-term DRX mode again. . However, if a packet is received before entering the long-term DRX mode again, the terminal maintains the short-term DRX mode again. In this case, the UE maintains the short-term DRX mode again from the 61st subframe to the 90th subframe (second interval, 960). As a result, the UE may maintain the short-term DRX mode continuously according to packet transmission.

In general, when the UE is in DRX operation, even if a packet is transmitted during inactivity time, the UE does not receive it. In general, if the UE knows that the UE is inactive time at the corresponding location, it shifts to the next activity time. After scheduling, the terminal may receive a packet at the active time.

In other words, since the terminal has a short-term DRX, if there is a PDCCH for the terminal in a duration, the DRX inactivity timer ends or the DRX retransmission timer ends. After the MAC contention resolution timer or the end of the MAC contention resolution timer (MAC) changed from the long-term DRX mode to short-term DRX mode to operate. In this case, the UE does not need to increase the battery consumption by checking the PDCCH because the UE wakes up frequently by changing to the short-term DRX mode according to the traffic type. In the case of FIG. 9, since the traffic generation period is 30 ms, the UE repeats the duration (or activity time) in a shorter period and monitors the PDCCH in a subframe, which may be an unnecessary operation.

Therefore, it is necessary to set the DRX in consideration of the traffic pattern or the packet IAT.

10 illustrates a DRX operation of a terminal considering a packet IAT according to an embodiment of the present invention. One square represents a subframe, the colored subframe represents the packet arrival time, and the hatched subframe represents the duration of the DRX cycle. Referring to FIG. 10, when the UE knows the packet IAT and the base station can also grasp the packet IAT, the following DRX operation may be performed. When the UE receives the packet by checking the PDCCH after the short-term DRX interval, unlike in FIG. 9, the terminal enters the long-term DRX mode without entering the short-term DRX mode in the second interval 1060 after the first interval 1030. Can be.

The UE allows entry of the short-term DRX mode in the first interval 1030 from the 31 st subframe to the 60 th subframe due to the reception of the first packet in the eleventh subframe. Thereafter, in the short-term DRX mode, the UE receives the second packet in the 31st subframe, and immediately enters the long-term DRX mode without entering the short-term DRX in the second section 1060 after the expiration of the DRX short-cycle timer in the first section 1030. You can do that.

In this case, the terminal does not enter the short-term DRX mode, and the process of entering the long-term DRX mode may follow the following method.

First, the terminal may implicitly determine. The UE may know that the packet IAT is 30ms. At this time, the first packet is received, after the long-term DRX cycle ends, enters the short-term DRX mode, the terminal in the short-term DRX mode in the second interval (1060) after the first interval (1030) covered by one DRX short-cycle timer. If the terminal tries to maintain (since the terminal receives the second packet), the terminal may determine and operate the terminal itself to enter the long-term DRX mode rather than the short-term DRX mode in consideration of the packet IAT value.

Depending on when the UE can know the value for the packet IAT, the UE may operate in the following two ways.

a. This is the case where the UE knows the packet IAT value after entering the short DRX mode after the long term DRX. At this time, the UE knows the value for the packet IAT and can continue to maintain the long-term DRX mode without entering the short-term DRX mode.

b. This is the case where the UE knows the packet IAT value after entering the short DRX mode after the long term DRX. At this time, the UE knows the value for the packet IAT, but can be converted to the long-term DRX mode after the short-term DRX mode interval proceeds while the short-term DRX mode is in progress.

Second, the base station may directly transmit the RRC connection reconfiguration message including the DRX reconfiguration information as described in FIG. The terminal may change the DRX related parameters or the DRX cycle mode through the DRX reconfiguration based on the DRX reconfiguration information.

As described above, when the terminal considers the packet IAT and enters the short-term DRX mode without entering the short-term DRX mode, the terminal may be unnecessarily changed to the short-term DRX mode or the like to prevent the battery waste. However, in the example of FIG. 10, the length of the DRX cycle is not changed, and there is still a waste of monitoring the PDCCH at the time when the UE is not required.

11 illustrates a DRX operation of a terminal considering packet IAT according to another embodiment of the present invention. One square represents a subframe, the colored subframe represents the packet arrival time, and the hatched subframe represents the duration of the DRX cycle.

Referring to FIG. 11, after the first interval 1130, the UE changes and operates both the DRX cycle mode and the DRX cycle length through DRX reconfiguration in consideration of the packet IAT. Unlike FIG. 10, the UE enters the long-term DRX mode in consideration of the packet IAT in the second section 1160 after the first section 1130 and adjusts the length of the long-term DRX cycle. In this case, the UE may increase the DRX efficiency by adjusting the length of the DRX cycle for PDCCH reception to an optimal value. While the terminal operates in the short-term DRX mode during the first interval 1130, the terminal changes from the second interval 1160 to the long-term DRX mode, and adaptively takes the length of the long-term DRX cycle in consideration of the packet IAT. Changed to 30ms equal to the IAT value. In this case, the UE may increase the DRX efficiency by monitoring the PDCCH according to the time point at which the packet comes.

12 illustrates a DRX operation of a terminal considering a packet IAT according to another embodiment of the present invention. One square represents a subframe, the colored subframe represents the packet arrival time, and the hatched subframe represents the duration of the DRX cycle.

Referring to FIG. 12, the terminal does not enter the short-term DRX mode in the first section 1230 after the long-term DRX mode and immediately maintains the long-term DRX mode. The terminal can know the packet IAT, and the base station can also know the packet IAT. When the UE changes to the short-term DRX mode, if the packet IAT is actually 30ms, the PDCCH must be monitored by waking up every 10ms in the short-term DRX mode.However, even though the terminal knows the packet IAT, the UE wakes up every 10ms to monitor the PDCCH. It is an unnecessary action to do. Accordingly, the terminal may maintain the long-term DRX mode from the first interval 1230 without entering the short-term DRX mode in consideration of the packet IAT value.

Specifically, while the packet IAT of the terminal is maintained at 30 ms, the base station does not enter the short-term DRX mode in the first section 1230 after the long-term DRX mode based on the packet IAT information, and operates in the long-term DRX mode immediately. . In the long-term DRX mode, if the duration of the duration (on duration) does not match the packet arrival time, even if the base station schedules the packet, the terminal cannot receive it. In general, since the base station knows the DRX configuration of the terminal, the base station may perform scheduling at the duration of the duration of the long-term DRX mode. In this case, the terminal may not enter the short-term DRX mode unnecessarily and may reduce battery consumption.

13 illustrates a DRX operation of a terminal in consideration of a packet IAT according to another embodiment of the present invention. One square represents a subframe, the colored subframe represents the packet arrival time, and the hatched subframe represents the duration of the DRX cycle.

Referring to FIG. 13, the terminal does not enter the short-term DRX mode after the long-term DRX mode, immediately maintains the long-term DRX mode, and changes the length of the long-term DRX cycle. After receiving the packet in the eleventh subframe, which is the duration of the long-term DRX mode, the UE does not enter the short-term DRX mode from the thirty-first subframe, the next subframe of the thirtieth subframe, at which the long-term DRX cycle ends. In consideration, it may operate with a long DRX cycle (1330). In this case, the terminal may ignore the short-term DRX even if configured, and immediately maintain the long-term DRX mode. In addition, the terminal may adjust the long-term DRX cycle length based on the packet IAT. Specifically, the terminal reconfigures the long DRX cycle length to 30 ms based on the packet IAT. In this case, the terminal may operate in a long-term DRX cycle of the same interval as the packet IAT, and improve the DRX efficiency.

As described above, the terminal may reconfigure the DRX-related parameters in consideration of the packet IAT, perform an efficient DRX operation based on this, and increase the power saving efficiency of the terminal by preventing unnecessary wakeup of the terminal.

Meanwhile, in FIGS. 10 to 13, the time point at which the UE performs DRX reconfiguration based on the packet IAT value may vary depending on the time point at which the DRX reconfiguration information is obtained. For example, when the UE acquires DRX reconfiguration information while operating in the short-term DRX mode, DRX reconfiguration may be performed as shown in FIGS. 10 and 11. As another example, when the UE acquires DRX reconfiguration information before operating in the short-term DRX mode, DRX reconfiguration may be performed as shown in FIGS. 12 and 13. Of course, the DRX reconfiguration may be performed after a certain period irrespective of the timing at which the UE acquires the DRX reconfiguration information. In this case, the example of FIGS. 10 to 13 may be independent of the timing at which the UE receives the DRX reconfiguration information. have.

Referring to FIG. 14, the terminal calculates a packet IAT (S1400). As described above, the method for calculating the packet IAT may include both a method for calculating a packet IAT defined in terms of a downlink (DL) and a method for calculating a packet IAT defined in an uplink (UL).

The terminal transmits the packet IAT information indicating the calculated packet IAT to the base station (S1410). As an example, the packet IAT information may be transmitted through dedicated signaling or MAC CE for the terminal. As another example, the packet IAT information may be transmitted as a RRC message through a measurement report message or an RRC UE assistance information message.

The terminal receives the DRX reconfiguration information from the base station (S1420). The DRX reconfiguration information may be transmitted from a base station using an RRC connection reconfiguration message.

The terminal reconfigures DRX related parameters based on the DRX reconfiguration information (S1430). Here, the DRX reconfiguration may include an operation of prohibiting switching to the short-term DRX mode. Or DRX reconstruction may include changing the length of the long term DRX cycle or the length of the short term DRX cycle.

Referring to Figure 15, the base station receives the packet IAT information from the terminal (S1500). As an example, the packet IAT information may be received through dedicated signaling or MAC CE for the terminal. As another example, the packet IAT information may be received as a RRC message through a measurement report message or an RRC UE assistance information message.

The base station reconfigures the DRX based on the packet IAT information (S1510). When the base station receives the packet IAT information, the base station reconfigures the DRX related parameters such that the transmission time of the estimated downlink packet based on the packet IAT information matches the on duration (or active time) of the DRX mode. As one example, the base station may reconfigure the DRX related parameters to change the short term DRX mode to the long term DRX mode previously. As another example, the base station may reconfigure the DRX related parameters in a manner that increases or decreases the length of the short term DRX cycle or the length of the long term DRX cycle. As another example, the base station may reconfigure the DRX related parameters to maintain the long-term DRX mode so as not to switch from the long-term DRX mode to the short-term DRX mode.

The base station transmits DRX reconfiguration information to the terminal (S1520). The DRX reconfiguration information may be transmitted using an RRC connection reconfiguration message.

Referring to FIG. 16, referring to FIG. 16, the terminal 1600 includes a receiver 1605, a terminal processor 1610, and a transmitter 1620. The terminal processor 1610 further includes a DRX processor 1611 and an IAT processor 1612.

The IAT processing unit 1612 calculates a packet IAT. As described above, the method for calculating the packet IAT may include both a method for calculating a packet IAT defined from a downlink (DL) point of view and a method for calculating a packet IAT defined from an uplink (UL) point of view.

The IAT processing unit 1612 transfers the calculated packet IAT to the transmitting unit 1620.

The transmitter 1620 transmits the packet IAT information generated by the IAT processor 1612 to the base station 1950. Here, the packet IAT information may be transmitted through dedicated signaling or medium access control (MAC) control element (CE) for the terminal. Alternatively, the packet IAT information may be transmitted as a RRC message through a measurement report message or an RRC UE assistance information message.

The receiver 1605 may receive DRX reconfiguration information from the base station. Here, the DRX reconfiguration information is generated by the DRX processing unit 1701 of the base station 1650 in consideration of the packet IAT calculated by the IAT processing unit 1612 of the terminal 1600 or the IAT processing unit 1672 of the base station 1650, and in the DRX mode. It includes parameter information that can change or change the length of the DRX cycle.

The DRX processor 1611 reconfigures the DRX of the terminal based on the DRX reconfiguration information. DRX reconfiguration may include an operation to prohibit switching to short-term DRX mode. Or DRX reconstruction may include changing the length of the long term DRX cycle upon switching to long term DRX.

An example in which the DRX processor 1611 reconfigures the DRX of the terminal 1600 may include the examples described with reference to FIGS. 10 to 13.

Meanwhile, the DRX processor 1611 receives the packet IAT value from the IAT processor 1612 of the terminal 1600 without receiving the DRX reconfiguration information transmitted from the base station 1650, and based on this, the DRX processor 1611 reconfigures the DRX related parameters. It may be.

The base station 1650 includes a transmitter 1655, a receiver 1660, and a base station processor 1670. The base station processor 1670 includes a DRX processor 1671 and an IAT processor 1672.

The receiver 1660 receives the packet IAT information from the terminal. The receiver transmits the received packet IAT information to the DRX processor 1671.

The DRX processing unit 1701 performs DRX reconstruction based on the packet IAT information. That is, the DRX processor 1671 reconfigures the DRX related parameter such that the transmission time of the downlink packet estimated based on the packet IAT matches the duration (or active time). As an example, the DRX processor 1671 may reconfigure DRX related parameters to change the short-term DRX mode to the long-term DRX mode. As another example, the base station may reconfigure the DRX related parameters in a manner that increases or decreases the length of the long term DRX cycle. As another example, the DRX processing unit 1701 may reconfigure DRX related parameters to maintain the long-term DRX mode so that the long-term DRX mode is not switched to the short-term DRX mode previously.

On the other hand, the base station 1650 may further include an IAT processing unit 1672. The IAT processing unit 1672 calculates a packet IAT. As described above, the method for calculating the packet IAT may include both a method for calculating a packet IAT defined from a downlink (DL) point of view and a method for calculating a packet IAT defined from an uplink (UL) point of view. The IT processor 1672 may transfer the calculated packet IAT to the DRX processor 1701.

The transmitter 1655 transmits the DRX reconfiguration information to the terminal 1600. The DRX reconfiguration information may be transmitted using an RRC connection reconfiguration message.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited thereto. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

Claims

A terminal for performing a discontinuous reception (DRX) operation in consideration of an inter-arrival time of a packet in a wireless communication system,

An IAT processing unit for calculating a packet IAT;

A transmitter for transmitting the packet IAT to a base station;

A receiver configured to receive modified DRX reconfiguration information from the base station based on the packet IAT; And

And a DRX processor configured to perform DRX reconfiguration based on the received DRX reconfiguration information.
The method of claim 1,

The IAT processing unit, characterized in that for calculating the packet IAT on the basis of when the packet arrives in the packet data convergence protocol (PDCP) layer of the terminal.
The method of claim 2,

When the plurality of radio bearer (RB) is configured in the terminal, the IAT processing unit, characterized in that for calculating the respective packet IAT for each of the plurality of radio bearer, the terminal.
The method of claim 2,

When a plurality of radio bearers are configured in the terminal, the IAT processing unit determines the average value of the individual packet IATs as the packet IAT for each of the plurality of radio bearers, or any one of the individual packet IATs is the packet IAT. Characterized in that, the terminal.
The method of claim 1,

The transmitting unit transmits the packet IAT to dedicated signaling, medium access control (MAC) control element (CE), measurement report message, and RRC (Radio Resource) for the terminal. Control) The terminal, characterized in that for transmitting to the base station via at least one of the assistant information (assistant information) message.
A base station for controlling a DRX operation of a terminal considering the arrival interval (IAT) of a packet in a wireless communication system,

Receiving unit for receiving a packet IAT from the terminal;

A DRX processor that modifies a DRX related parameter based on the received packet IAT; And

And a transmitter for transmitting DRX reconfiguration information including the changed DRX related parameter to the terminal.
The method of claim 6,

The DRX processor performs a change of the DRX related parameter including a DRX mode and a length of a DRX cycle indicating one of a long DRX mode and a short DRX mode. .
The method of claim 7, wherein

The DRX processor is characterized in that for changing the DRX parameter by changing the DRX mode or the length of the DRX cycle, the base station.
In the DRX method considering the packet arrival interval by the terminal in a wireless communication system,

Calculating a packet IAT;

Transmitting the packet IAT to a base station;

Receiving modified DRX reconfiguration information from the base station based on the packet IAT; And

Performing a DRX reconfiguration based on the received DRX reconfiguration information.
The method of claim 9,

DRX method, characterized in that for calculating the packet IAT on the basis of when the packet arrives in the PDCP layer of the terminal.
The method of claim 10,

In calculating the packet IAT, when a plurality of radio bearers (RBs) are configured in the terminal, the individual packet IAT is calculated for each of the plurality of radio bearers.
The method of claim 10,

When a plurality of radio bearers are configured in the terminal, the IAT processing unit determines the average value of the individual packet IATs as the packet IAT for each of the plurality of radio bearers, or any one of the individual packet IATs is the packet IAT. DRX method, characterized in that determined by.
The method of claim 9,

The packet IAT is a DRX method, characterized in that transmitted to the base station through at least one of a dedicated signaling for the terminal, a media access control control element, a measurement report message, and an RRC terminal assistance information message.
A method of controlling DRX operation of a terminal in consideration of a packet arrival interval by a base station in a wireless communication system,

Receiving a packet IAT from the terminal;

Performing modification of a DRX related parameter based on the received packet IAT; And

And transmitting DRX reconfiguration information including the changed DRX related parameter to the terminal.
The method of claim 14,

And performing a change of said DRX related parameter including a DRX mode and a length of a DRX cycle, indicating either one of a long DRX mode and a short DRX mode.
The method of claim 14,

Changing the DRX parameter by changing the DRX mode or the length of the DRX cycle.