Method and apparatus for applying multiple DRX in carrier aggregation technology in a mobile communication system

Abstract

The present disclosure relates to a communication technology for integrating IoT technology with a 5G communication system for supporting a higher data transmission rate than 4G systems, and a system therefor. The present disclosure may be applied to intelligent services (e.g., smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail business, security and safety-related services, etc.) based on 5G communication technology and IoT-related technologies. The present invention discloses a method and apparatus for setting and applying multiple discontinuous reception (DRX).

Description

Technical Field

[0001] The present disclosure relates to methods and apparatuses for configuring and applying multiple discontinuous reception (DRX). Background Art

[0002] In order to meet the growing demand for wireless data services since the commercialization of 4G communication systems, efforts have been made to develop improved 5G or pre-5G communication systems. Therefore, 5G or pre-5G communication systems are also referred to as "super 4G network systems" or "post-long term evolution (LTE) systems". To achieve high data rates, 5G communication systems are being considered for implementation in the super high frequency (millimeter wave, mmWave) band (e.g., 60 GHz band). To reduce the path loss of radio waves and increase the transmission distance in the mmWave band, various techniques including beamforming, massive multiple input multiple output (massive MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and large antennas are being considered for 5G communication systems. In addition, to improve the system network in 5G communication systems, technical developments are being carried out on evolved small cells, advanced small cells, cloud radio access network (cloud RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, coordinated multi-point (CoMP), interference cancellation, etc. In addition, advanced coding and modulation (ACM) schemes such as hybrid frequency shift keying and quadrature amplitude modulation (FQAM) and sliding window superposition coding (SWSC), and advanced access technologies such as filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) are also being developed for 5G systems.

[0003] Meanwhile, the Internet is evolving from a human-centered network where humans create and consume information to the Internet of Things (IoT), in which distributed elements such as things exchange and process information. There has also emerged the Internet of Everything (IoE) technology that combines IoT technology with big data processing technology by connecting to cloud servers. To implement the IoT, technical elements related to sensing, wired / wireless communication and network infrastructure, service interfaces, and security are required, and technologies for interconnecting things, such as sensor networks, machine-to-machine (M2M) or machine type communication (MTC), have been studied in recent years. In the IoT environment, intelligent Internet technology services can be provided, which collect and analyze data created by interconnected things to add new value to human life. Through the integration and combination of existing information technologies and various industries, IoT technology can be applied to various fields such as smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart consumer electronics, and advanced medical services.

[0004] Therefore, various attempts are being made to apply the 5G communication system to the IoT network. For example, technologies such as sensor networks and machine-to-machine (M2M) or machine type communication (MTC) are being realized by using 5G communication technologies including beamforming, MIMO, and array antennas. The application of cloud RAN as the above big data processing technology may be an example of the convergence of 5G technology and IoT technology.

[0005] On the other hand, DRX is applied to minimize the power consumption of the terminal, and a technique for monitoring only a preset PDCCH to obtain scheduling information. DRX can operate in both the idle mode and the connected mode, and the operation methods are different. Summary of the Invention

[0006] Technical Problem

[0007] Since only two types of DRX cycles can be configured in the related art, there are efficiency problems such as the inability to dynamically change the DRX cycle according to various DRB characteristics, traffic patterns, buffer states, etc. Therefore, an object of the present disclosure is to provide a method for applying multiple DRX configurations to multiple serving cells.

[0008] Solution to the Problem

[0009] To solve the above problems, a method performed by a terminal in a wireless communication system according to an embodiment of the present disclosure may include: receiving first discontinuous reception DRX configuration information and second DRX configuration information from a base station; performing physical downlink control channel (PDCCH) monitoring in a first DRX group using a first active time based on the first DRX configuration information, and performing PDCCH monitoring in a second DRX group using a second active time based on the second DRX configuration information; receiving information associated with a DRX cycle in one of the first DRX group and the second DRX group; and after a specific time point, starting a timer for the DRX cycle determined by the information in each of the first DRX group and the second DRX group, wherein the first DRX group and the second DRX group are determined based on a frequency range FR.

[0010] In addition, a method performed by a base station in a wireless communication system according to an embodiment of the present disclosure may include: sending first discontinuous reception (DRX) configuration information and second DRX configuration information to a terminal; sending a physical downlink control channel (PDCCH) to a first DRX group using a first active time based on the first DRX configuration information and sending the PDCCH to a second DRX group using a second active time based on the second DRX configuration information; and sending information associated with a DRX cycle to one of the first DRX group and the second DRX group, wherein, based on the reception of the information by the terminal, a timer for the DRX cycle associated with the information is started in each of the first DRX group and the second DRX group after a specific time point, and wherein the first DRX group and the second DRX group are determined based on a frequency range (FR).

[0011] In addition, a terminal in a wireless communication system according to an embodiment of the present disclosure may include: a transceiver; and a controller configured to: control the transceiver to receive first discontinuous reception (DRX) configuration information and second DRX configuration information from a base station; perform physical downlink control channel (PDCCH) monitoring in a first DRX group using a first active time based on the first DRX configuration information and perform PDCCH monitoring in a second DRX group using a second active time based on the second DRX configuration information; control the transceiver to receive information associated with a DRX cycle in one of the first DRX group and the second DRX group; and start a timer for the DRX cycle determined by the information in each of the first DRX group and the second DRX group after a specific time point, wherein the first DRX group and the second DRX group are determined based on a frequency range FR.

[0012] In addition, a base station in a wireless communication system according to an embodiment of the present disclosure may include: a transceiver; and a controller configured to: control the transceiver to send first discontinuous reception (DRX) configuration information and second DRX configuration information to a terminal; control the transceiver to send a physical downlink control channel PDCCH to a first DRX group using a first active time based on the first DRX configuration information and send the PDCCH to a second DRX group using a second active time based on the second DRX configuration information; and control the transceiver to send information associated with a DRX cycle to one of the first DRX group and the second DRX group, wherein, based on the reception of the information by the terminal, a timer for the DRX cycle associated with the information is started in each of the first DRX group and the second DRX group after a specific time point, and wherein the first DRX group and the second DRX group are determined based on a frequency range FR.

[0013] Advantages of the Invention

[0014] According to an embodiment of the present disclosure, one DRX is made to correspond to a group of one or more serving cells, and the corresponding DRX is applied to the serving cells belonging to one group, so as to achieve the effect of minimizing the terminal power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a diagram showing the architecture of a next-generation mobile communication system.

[0016] Figure 2 is a diagram for explaining DRX operations in the existing LTE technology.

[0017] Figure 3 is a diagram for explaining DRX operations when receiving a (long) DRX command MAC CE.

[0018] Figure 4 is a flowchart of a method for providing multiple DRX configuration information in the present disclosure.

[0019] Figure 5 is a diagram for explaining a first scenario in the present disclosure.

[0020] Figure 6 is a diagram for explaining a second scenario in the present disclosure.

[0021] Figure 7 is a diagram for explaining a third scenario in the present disclosure.

[0022] Figure 8 is a diagram for explaining UE operations in the present disclosure.

[0023] Figure 9 is a diagram for explaining base station operations in the present disclosure.

[0024] Figure 10 is a block diagram showing the internal structure of a UE to which the present disclosure is applied.

[0025] Figure 11 is a block diagram showing the structure of a base station according to the present disclosure. DETAILED DESCRIPTION

[0026] The operating principle of the present disclosure will be described in detail below with reference to the accompanying drawings. In the following description of the present disclosure, descriptions of well-known functions and structures incorporated herein may be omitted to avoid obscuring the subject matter of the present disclosure. The terms described below are defined in consideration of their functions in the present disclosure, and these terms may vary depending on the intention or habit of the user or operator. Therefore, their meanings should be determined based on the overall content of this specification.

[0027] In the following description of the present disclosure, descriptions of well-known functions and structures incorporated herein may be omitted to avoid obscuring the subject matter of the present disclosure. Next, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0028] The terms used in the following description for identifying access nodes, indicating network entities, indicating messages, indicating interfaces between network entities, and indicating various identification information are for the purpose of facilitating description. Therefore, the present disclosure is not limited by the terms to be described later, and other terms that refer to objects having equivalent technical meanings may be used.

[0029] For convenience of description, the present disclosure uses the terms and names defined in the 3GPP LTE (3rd Generation Partnership Project Long Term Evolution) standard. However, the present disclosure is not limited by the above terms and names, and can be equally applied to systems conforming to other standards. In the present disclosure, for convenience of description, "eNB" may be used interchangeably with "gNB". That is, a base station described as an eNB may indicate a gNB.

[0030] In the following description of the present disclosure, descriptions of well-known functions and structures incorporated herein may be omitted to avoid obscuring the subject matter of the present disclosure. Next, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0031] Figure 1 is a diagram showing the EN-DC architecture of a next-generation mobile communication system.

[0032] EN-DC refers to the dual connection of EUTRAN (LTE system) and NR (next-generation mobile communication system), and is a scenario where a UE is simultaneously connected to two different types of systems to receive services.

[0033] Refer to Figure 1 , as shown in the figure, the radio access network of the next-generation mobile communication system consists of next-generation base stations (New Radio Node B, hereinafter referred to as gNB) 1a-10 and an Access and Mobility Management Function (AMF) (New Radio Core Network) 1a-05. A user terminal (New Radio User Equipment, hereinafter referred to as NR UE or terminal) 1a-15 is connected to an external network through gNB 1a-10 and AMF 1a-05.

[0034] In Figure 1In this case, gNB 1a-10 corresponds to the evolved Node B (eNB) of the existing LTE system. gNB 1a-10 is connected to NR UE 1a-15 via a radio channel, and it can provide services of better quality than those of the existing Node B. Since all user services in the next-generation mobile communication system are served via a shared channel, an entity that performs scheduling by collecting status information such as buffer status, available transmission power status, and channel status of each UE is required, and gNB 1a-10 is responsible for this matter. One gNB normally controls multiple cells. To achieve ultra-high-speed data transmission compared to the existing LTE, a bandwidth exceeding the existing maximum bandwidth can be utilized, and beamforming technology can be additionally combined with orthogonal frequency division multiplexing (OFDM) used as a radio access technology. In addition, an adaptive modulation and coding (AMC) scheme that determines a modulation scheme and a channel coding rate to match the channel status of the UE is applied.

[0035] AMF 1a-05 performs functions such as mobility support, bearer configuration, and quality of service (QoS) configuration. AMF is an entity that is responsible not only for mobility management but also for various control functions for the UE, and is connected to multiple base stations. In addition, the next-generation mobile communication system can interoperate with the existing LTE system, and AMF is connected to MME 1a-25 via a network interface. MME can be connected to eNB 1a-30, which is an existing base station. In the EN-DC scenario, the gNB can be controlled by being connected to the eNB.

[0036] Figure 2 is a diagram for explaining DRX operation.

[0037] DRX is applied to minimize the power consumption of the UE, and is a technology that only monitors a preset PDCCH to obtain scheduling information. DRX can operate in both the idle mode and the connected mode, and the operation methods are different. This disclosure relates to the connected mode.

[0038] Continuously monitoring the PDCCH to obtain scheduling information will cause the UE to consume a large amount of power. The basic DRX operation has a DRX cycle 1b-00, and only monitors the PDCCH during the on-duration 1b-05. In the connected mode, two values, long DRX and short DRX, are set for the DRX cycle. Generally, the long DRX cycle is applied, and if necessary, the base station can trigger the short DRX cycle by using a MAC control element (CE). After a specific time, the UE changes from the short DRX cycle to the long DRX cycle.

[0039] The initial scheduling information for a specific UE is provided only on a preset PDCCH. Therefore, the UE can minimize power consumption by periodically monitoring only the preset PDCCH. If scheduling information (1b-10) for a new packet is received on the PDCCH during the on-duration period 1b-05, the UE starts a DRX inactivity timer (1b-15). The UE remains active during the DRX inactivity timer. That is, PDCCH monitoring continues.

[0040] In addition, a HARQ RTT timer (1b-20) is started. The HARQ RTT timer is applied to prevent the UE from unnecessarily monitoring the PDCCH during the HARQ round-trip time (RTT), and the UE does not need to perform PDCCH monitoring during the running time of this timer. However, when the DRX inactivity timer and the HARQ RTT timer are running simultaneously, the UE continues to monitor the PDCCH based on the DRX inactivity timer. When the HARQ RTT timer expires, a DRX retransmission timer (1b-25) is started. When the DRX retransmission timer is running, the UE must perform PDCCH monitoring. Generally, during the running time of the DRX retransmission timer, scheduling information (1b-30) for HARQ retransmission is received. When the UE receives the scheduling information, the UE immediately stops the DRX retransmission timer and starts the HARQ RTT timer again. The above operations continue until the packet is successfully received (1b-35).

[0041] The configuration information related to DRX operation in the connected mode is delivered to the UE through an RRCConnectionReconfiguration (RRC connection reconfiguration) message. The on-duration timer, the DRX inactivity timer, and the DRX retransmission timer are defined by the number of PDCCH subframes. After starting the timer, when the configured number of subframes (which are defined as PDCCH subframes) pass by, the timer expires. All downlink subframes belong to the PDCCH subframes in FDD, and downlink subframes and special subframes correspond to the PDCCH subframes in TDD. In TDD, downlink subframes, uplink subframes, and special subframes exist in the same frequency band. Among them, downlink subframes and special subframes are considered PDCCH subframes.

[0042] The base station can configure two states of long DRX and short DRX. Generally, the base station will consider the power preference indication information reported by the UE, the UE mobility record information, and the characteristics of the configured data radio bearer (DRB) to use one of these two states. The transition between the two states is carried out by the expiration of a specific timer or by sending a specific MAC CE to the UE.

[0043] In the existing LTE technology, since only two DRX cycles can be configured, it is impossible to dynamically change the DRX cycle according to various DRB characteristics, service modes, and buffer states.

[0044] The present disclosure is characterized in that multiple DRXs can be configured, and one of the configured multiple DRXs is applied to one or more serving cells. In particular, in order to minimize the UE power consumption, it is characterized in that a group of one or more serving cells corresponds to one DRX, and the serving cells belonging to the group apply the DRX. For example, in order to minimize the UE power consumption, it is desirable to apply the same DRX to the serving cells operating in the same radio frequency (RF) chain.

[0045] In the case of carrier aggregation (CA), the base station can separately provide the DRX applied to those serving cells belonging to frequency range 1 (FR1) and the DRX applied to those serving cells belonging to frequency range 2 (FR2). In the present disclosure, the serving cells belonging to FR1 are referred to as the primary DRX group, and the serving cells belonging to FR2 are referred to as the secondary DRX group. Alternatively, the DRX group to which the PCell belongs can be referred to as the primary DRX group, and the DRX group that does not include the PCell can be referred to as the secondary DRX group.

[0046] Figure 3 It is a diagram for explaining the DRX operation when receiving a (long) DRX command MAC CE.

[0047] The UE defaults to applying the long DRX cycle (1c-10) and monitors the PDCCH during the onDuration (on duration) period (1c-05) of each cycle.

[0048] When obtaining scheduling information during the onDuration period (1c-15), the UE starts the drx-InactivityTimer (drx-inactivity timer) (1c-20). The UE can receive a long DRX command MAC CE or a DRX command MAC CE from the base station during the active time (1c-25). When indicating the use of the long DRX cycle, a long DRX command MAC CE is sent from the base station, and when indicating the use of the short DRX cycle, a DRX command MAC CE is sent. When the drx-onDurationTimer (drx-on duration timer) or the drx-InactivityTimer is running, this is regarded as the active time, and the UE performs PDCCH monitoring.

[0049] When the UE receives one of the above MAC CE, the UE stops the running drx-InactivityTimer timer and drx-onDurationTimer timer (1c-30), and uses the long DRX cycle or the short DRX cycle. If the short DRX cycle (1c-40) is used, the UE starts the drx-ShortCycleTimer (drx-short cycle timer) (1c-35). When the drx-ShortCycleTimer expires (1c-45), the UE uses the long DRX cycle (1c-50).

[0050] When the UE uses short DRX or long DRX, the onDuration timer is started at a time that satisfies the following equation, generating the onDuration period.

[0051] If the short DRX cycle is used, then apply [(SFN × 10) + subframe number] modulo (drx-ShortCycle) = (drx-StartOffset) modulo (drx-ShortCycle);

[0052] If the long DRX cycle is used, then apply [(SFN × 10) + subframe number] modulo (drx-LongCycle) = drx-StartOffset; and when the subframe that satisfies the above equation starts, the drx-onDurationTimer is started after the drx-SlotOffset (drx-slot offset).

[0053] Figure 4 It is a flowchart of a method for providing multiple DRX configuration information in the present disclosure.

[0054] UE 1d-05 reports its capability information (1d-15) to the base station 1d-10. The capability information includes an indicator indicating that the UE is capable of configuring multiple DRXs when multiple serving cells are configured. The base station composes multiple DRX configuration information (1d-20) to be configured for the UE. In the present disclosure, it is considered to provide two DRX configuration information. Here, it is necessary to configure the serving cells to which each DRX configuration information is applied. In the present disclosure, the following options are considered.

[0055] - Option 1: The serving cells belonging to FR1 apply the first DRX configuration information, and the serving cells belonging to FR2 apply the second DRX configuration information

[0056] - Option 2: Define an indicator indicating which DRX configuration information is applied to the configuration information of each serving cell

[0057] - Option 3: The UE determines the serving cells to which two DRX configuration information is to be applied.

[0058] In the case of Option 1, since the DRX configuration information to be applied is automatically determined according to the FR to which the serving cell belongs, the base station does not need to separately send an indicator indicating this to the UE. In Option 1, it is assumed that the UE has separate RF modems for FR1 and FR2. Therefore, if it does not, the expected performance improvement may not be achieved.

[0059] In the case of option 2, the base station must know in advance the DRX group information that is beneficial to the UE in saving power consumption. To this end, the UE must report it to the base station through a capability information reporting procedure or a specific reporting procedure.

[0060] In the case of option 3, the base station sends only two pieces of DRX configuration information without DRX group information to the UE through the RRCReconfiguration message. However, it is assumed that the PCell always applies the first DRX configuration information. The UE sends the base station service cell information (DRX group information) to which each DRX configuration information is applied through the RRCReconfigurationComplete message as a response message to the RRCReconfiguration message. In option 3, since the UE directly indicates the service cell to which each DRX configuration information is applied in consideration of the configured SCell, there is no need to report the information required to configure the DRX group to the base station in advance.

[0061] The base station configures the SCell together with multiple DRX configuration information to the connected mode UE (1d-25). Then, the corresponding DRX configuration information is applied to each serving cell (1d-30). The UE sends an RRCReconfigurationComplete message to the base station as a response message to the RRCReconfiguration message (1d-35). The serving cell information (DRX group information) to which each DRX configuration information is applied can be included in the above message.

[0062] The present disclosure is characterized in that the DRX configuration information applied to the primary DRX group includes all relevant parameters, as described above (drx-onDurationTimer, drx-InactivityTimer, drx-HARQ-RTT-TimerDL (drx-HARQ-RTT timer for downlink), drx-HARQ-RTT-TimerUL (drx-HARQ-RTT timer for uplink), drx-RetransmissionTimerDL (drx-retransmission timer for downlink), drx-RetransmissionTimerUL (drx-retransmission timer for uplink), drx-LongCycleStartOffset (drx-long cycle start offset), drx-ShortCycle (drx-short cycle), drx-ShortCycleTimer, drx-SlotOffset), and the DRX configuration information applied to the secondary DRX group only includes drx-onDurationTimer and drx-InactivityTimer. Since the scheduling units in FR1 and FR2 are different, even if only the above two parameters are provided separately, there is an advantage in terms of UE power consumption. In addition, even if the above two parameters are provided separately for each DRX group, the physical layer or UE requirements will not be significantly affected.

[0063] In the present disclosure, the drx-onDurationTimer and drx-InactivityTimer applied in the secondary DRX group are respectively referred to as drx-onDurationTimer2 and drx-InactivityTimer2, and are distinguished from the parameters applied in the primary DRX group.

[0064] When introducing drx-onDurationTimer2 and drx-InactivityTimer2, the present disclosure proposes UE operations that match the DRX cycles applied to the two DRX groups.

[0065] Figure 5 It is a diagram for explaining the first scenario in the present disclosure.

[0066] In the first scenario, when the UE receives a DRX command MAC CE from a serving cell belonging to one DRX group, the serving cells belonging to the other DRX group are not in the active time.

[0067] The UE defaults to applying long DRX cycles 1e-10 and 1e-60 to two DRX groups and monitors the PDCCH during the onDuration periods 1e-05 and 1e-55 of each cycle. Here, since the drx-onDurationTimer and drx-onDurationTimer2 are applied to the DRX groups respectively, the onDuration periods in the two DRX groups are different.

[0068] When scheduling information (1e-15) is obtained during the onDuration period in the primary DRX group, the UE starts the drx-InactivityTimer (1e-20). When scheduling information (1e-65) is also obtained during the onDuration period of the secondary DRX group, the UE starts the drx-InactivityTimer2 (1e-70). The UE can receive a DRX command MAC CE (or, a long DRX command MAC CE) (1e-25) from the base station during the active time in the primary DRX group. When receiving one of the MAC CEs, the UE stops the running drx-InactivityTimer timer and drx-onDurationTimer timer (1e-30) and uses a short DRX cycle (or a long DRX).

[0069] If a short DRX cycle (1e-40) is used, the UE starts the drx-ShortCycleTimer (1e-35). Here, to match the DRX cycles applied to the two DRX groups, when one DRX group uses a short DRX cycle, the other DRX group also uses a short DRX cycle simultaneously. However, in the secondary DRX group, if it is not in the active time because the drx-InactivityTimer2 has expired or it has not been scheduled, since there is no running drx-InactivityTimer2 or drx-onDurationTimer2, there is no need to stop the relevant timers. When the drx-ShortCycleTimer expires (1e-45), the UE uses long DRX cycles for both groups (1e-50, 1e-95).

[0070] Figure 6 It is a diagram for explaining the second scenario in the present disclosure.

[0071] In the second scenario, when the UE receives DRX configuration information including short DRX configuration information from a serving cell belonging to one DRX group, the serving cell belonging to the other DRX group is not in the active time.

[0072] The UE by default applies the long DRX cycles 1f-10 and 1f-60 to two DRX groups and monitors the PDCCH during the onDuration periods 1f-05 and 1f-55 of each cycle. Here, since the drx-onDurationTimer and drx-onDurationTimer2 are applied to the DRX groups respectively, the onDuration periods in the two DRX groups are different.

[0073] When scheduling information (1f-15) is obtained during the onDuration period of the primary DRX group, the UE starts the drx-InactivityTimer (1f-20). When scheduling information is also obtained during the onDuration period of the secondary DRX group (1f-65), the UE starts the drx-InactivityTimer2 (1f-70). The UE may receive DRX configuration information (1f-25) from the base station during the active time in the primary DRX group. If the received DRX configuration information includes short DRX configuration information (or long DRX configuration information), the UE uses the short DRX cycle (or long DRX) when the running drx-InactivityTimer expires (1f-30).

[0074] If the short DRX cycle (1f-40) is used, the UE starts the drx-ShortCycleTimer (1f-35). Here, in order to match the DRX cycles applied to the two DRX groups, when one DRX group uses the short DRX cycle, the other DRX group also uses the short DRX cycle simultaneously. However, in the secondary DRX group, since the drx-InactivityTimer2 has expired or is not scheduled, it is not in the active time. Since there is no running drx-InactivityTimer2 or drx-onDurationTimer2, there is no need to stop the relevant timers. When the drx-ShortCycleTimer expires (1f-45), the UE uses the long DRX cycle for both groups (1f-50, 1f-95).

[0075] There may be a situation where the drx-onDurationTimer or drx-InactivityTimer is not running in the primary DRX group when a (long) DRX command MAC CE or DRX configuration information is received in the secondary DRX group. In this case, the UE operations for the primary DRX group and the UE operations for the secondary DRX group in Figure 5 and Figure 6 are swapped for application.

[0076] Figure 7 is a diagram for explaining the third scenario in the present disclosure.

[0077] In the third scenario, when the UE receives a DRX configuration information or a DRX command MAC CE including short DRX configuration information from a serving cell belonging to a DRX group, the serving cell belonging to another DRX group is in the active time.

[0078] The UE defaults to applying long DRX cycles 1g-10 and 1g-50 to the two DRX groups and monitors the PDCCH during the onDuration periods 1g-05 and 1g-45 of each cycle. Here, since the drx-onDurationTimer and drx-onDurationTimer2 are applied to the DRX groups respectively, the onDuration periods in the two DRX groups are different.

[0079] When scheduling information (1g-15) is obtained during the onDuration period of the primary DRX group, the UE starts the drx-InactivityTimer (1g-20). When scheduling information (1g-55) is also obtained during the onDuration period of the secondary DRX group, the UE starts the drx-InactivityTimer2 (1g-60). The UE may receive a DRX command MAC CE or DRX configuration information (1g-65) from the base station during the active time in the secondary DRX group.

[0080] When the UE receives a DRX command MAC CE (or a long DRX command MAC CE), the UE stops the running drx-InactivityTimer timer and drx-onDurationTimer timer and uses a short DRX cycle (or a long DRX). Otherwise, if the received DRX configuration information includes short DRX configuration information (or long DRX configuration information), the UE uses a short DRX cycle (or a long DRX) when the running drx-InactivityTimer expires (1g-70). If a short DRX cycle (1g-80) is used, the UE starts the drx-ShortCycleTimer (1g-75).

[0081] Here, in order to match the DRX cycles applied to the two DRX groups, when one DRX group uses a short DRX cycle, the other DRX group also uses a short DRX cycle at the same time. At this time, in the primary DRX group, since reasons such as the drx-InactivityTimer has not expired, it is still in the active time. The present disclosure proposes the following UE operations for the case where a DRX command MAC CE or DRX configuration information is received from the base station during the active time and the applied DRX cycle changes in one DRX group but the other DRX group is still in the active time.

[0082] Option 1-1 (1g-95): When receiving a DRX command MAC CE or DRX configuration information from a base station during the active time and the DRX cycle applied in one DRX group changes, the other DRX group in the active time also stops the drx-InactivityTimer or drx-onDurationTimer and applies the changed DRX cycle. This has an advantage in saving UE power consumption.

[0083] Option 1-2 (1g-25): When receiving a DRX command MAC CE or DRX configuration information from a base station during the active time and the DRX cycle applied in one DRX group changes, the other DRX group in the active time does not stop the drx-InactivityTimer or drx-onDurationTimer and applies the changed DRX cycle when all the above timers expire. This has an advantage in ensuring the freedom of scheduling for each DRX group.

[0084] Option 1-3: When receiving a DRX command MAC CE from a base station during the active time and the DRX cycle applied in one DRX group changes, the other DRX group in the active time also stops the drx-InactivityTimer or drx-onDurationTimer and applies the changed DRX cycle. On the other hand, when receiving DRX configuration information from a base station during the active time and the DRX cycle applied in one DRX group changes, the other DRX group in the active time does not stop the drx-InactivityTimer or drx-onDurationTimer and applies the changed DRX cycle when all the above timers expire.

[0085] If a short DRX cycle (1g-35) is applied, the drx-ShortCycleTimer is started in response thereto. If Option 1-1 is applied, there is no problem starting one drx-ShortCycleTimer regardless of the DRX group because the changed short DRX cycle is applied to both DRX groups simultaneously.

[0086] However, if Option 1-2 is applied, since the timing of applying the changed short DRX cycle in the two DRX groups is different, although the base station sets a value for the drx-ShortCycleTimer, a method of starting the drx-ShortCycleTimer for each DRX group can be considered. In this case, new UE operations are required according to the operations of the two timers.

[0087] Option 2-1: Regardless of the DRX group, there is a drx-ShortCycleTimer. This timer starts when the primary DRX group (or the DRX group to which the PCell belongs) uses the short DRX cycle, and when the timer expires, both DRX groups use the long DRX cycle.

[0088] Option 2-2 (1g-30, 1g-75): The drx-ShortCycleTimer can be started for each DRX group. In this case, the start times and expiration times of the two timers may be different from each other.

[0089] In Option 2-2, depending on whether the two timers are running, consider one of the following options for the applied DRX cycle.

[0090] Option 3-1 (1g-40): When at least one drx-ShortCycleTimer expires, the long DRX cycle is applied in both DRX groups.

[0091] Option 3-2 (1g-90): When both drx-ShortCycleTimers expire, the long DRX cycle is applied in both DRX groups.

[0092] There may be a situation where the drx-onDurationTimer or drx-InactivityTimer is not running in the secondary DRX group when a (long) DRX command MAC CE or DRX configuration information is received in the primary DRX group. In this case, Figure 7 the UE operations for the primary DRX group and the UE operations for the secondary DRX group in are interchanged for application.

[0093] Figure 8 is a diagram for explaining the UE operations in this disclosure.

[0094] In step 1h-05, the UE reports its capability information to the base station. This capability information includes an indicator indicating that the UE is capable of configuring multiple DRXs when multiple serving cells are configured.

[0095] In step 1h-10, the UE receives the SCell configuration from the base station. Here, multiple DRX configuration information can also be received, and the SCell configuration information includes an indicator indicating the DRX to be applied to each serving cell. The PCell always applies the first DRX configuration information.

[0096] In step 1h-15, the UE applies the configured DRX to the serving cells belonging to the corresponding group.

[0097] In step 1h-20, the terminal determines whether it has received a (long) DRX command MAC CE or DRX configuration information from the base station.

[0098] If a (long) DRX command MAC CE is received, in step 1h-25, the UE stops the running drx-onDurationTimer and drx-InactivityTimer.

[0099] In step 1h-30, if a DRX command MAC CE is received, the UE uses a short DRX cycle for the two DRX groups; if a long DRX command MAC CE is received, the UE uses a long DRX cycle for the two DRX groups.

[0100] If a short DRX cycle is used, in step 1h-35, the UE (re)starts the drx-ShortCycleTimer.

[0101] In step 1h-40, if short DRX configuration information is received, when the drx-InactivityTimer expires, the UE uses a short DX cycle for the two DRX groups; if long DRX configuration information is received, when the drx-InactivityTimer expires, the UE uses a short DX cycle for the two DRX groups.

[0102] If a short DRX cycle is used, in step 1h-45, the UE (re)starts the drx-ShortCycleTimer.

[0103] Figure 9 It is a diagram for explaining the base station operation in the present disclosure.

[0104] In step 1i-05, the base station receives a capability information report from a UE. The capability information includes an indicator indicating that the terminal is capable of configuring multiple DRXs when multiple serving cells are configured.

[0105] In step 1i-10, the base station composes multiple DRX configuration information to reduce the power consumption of the UE.

[0106] In step 1i-15, the base station configures an SCell to the connected-mode UE.

[0107] In step 1i-20, the base station may receive preferred DRX group information from the UE.

[0108] In step 1i-25, the base station applies the configured DRX to the serving cells belonging to the corresponding group.

[0109] Figure 10 It is a block diagram showing the internal structure of a UE to which the present disclosure is applied.

[0110] Referring to the accompanying drawings, the UE includes a radio frequency (RF) processor 1j-10, a baseband processor 1j-20, a storage device 1j-30, and a controller 1j-40.

[0111] The RF processor 1j-10 performs functions for transmitting and receiving signals through a radio channel, such as signal band conversion and amplification. That is, the RF processor 1j-10 performs up-conversion of the baseband signal provided by the baseband processor 1j-20 to an RF band signal and transmits it through an antenna, and performs down-conversion of the RF band signal received through the antenna to a baseband signal. For example, the RF processor 1j-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), and an analog-to-digital converter (ADC).

[0112] Although only one antenna is shown in the drawings, multiple antennas may be provided for the UE. In addition, the RF processor 1j-10 may include multiple RF chains. In addition, the RF processor 1j-10 may perform beamforming. For beamforming, the RF processor 1j-10 may adjust the phase and amplitude of the signals transmitted and received through multiple antennas or antenna elements. In addition, the RF processor 1j-10 may perform MIMO and may receive several layers during MIMO operation.

[0113] The baseband processor 1j-20 performs conversion between a baseband signal and a bit string according to the physical layer specification of the system. For example, during data transmission, the baseband processor 1j-20 generates complex symbols by encoding and modulating the transmitted bit string. In addition, during data reception, the baseband processor 1j-20 recovers the received bit string by demodulating and decoding the baseband signal provided by the RF processor 1j-10. For example, in the case of using orthogonal frequency division multiplexing (OFDM), for data transmission, the baseband processor 1j-20 generates complex symbols by encoding and modulating the transmitted bit string, maps the complex symbols to subcarriers, and forms OFDM symbols through an inverse fast Fourier transform (IFFT) operation and cyclic prefix (CP) insertion. In addition, for data reception, the baseband processor 1j-20 divides the baseband signal provided by the RF processor 1j-10 into OFDM symbols, recovers the signals mapped to subcarriers through a fast Fourier transform (FFT) operation, and recovers the received bit string through demodulation and decoding.

[0114] As described above, the baseband processor 1j-20 and the RF processor 1j-10 transmit and receive signals. Therefore, the baseband processor 1j-20 and the RF processor 1j-10 can be referred to as a transmitter, a receiver, a transceiver, or a communication unit. In addition, in order to support different radio access technologies, at least one of the baseband processor 1j-20 and the RF processor 1j-10 may include a plurality of communication modules. In addition, in order to process signals of different frequency bands, at least one of the baseband processor 1j-20 and the RF processor 1j-10 may include different communication modules. For example, different radio access technologies may include wireless LAN (e.g., IEEE802.11), cellular networks (e.g., LTE), etc. In addition, different frequency bands may include super high frequency (SHF) bands (e.g., 2.NRHz, NRhz) and millimeter wave (mmWave) bands (e.g., 60 GHz).

[0115] The storage device 1j-30 stores data such as basic programs, application programs, and configuration information for the operation of the UE. In particular, the storage device 1j-30 may store information about a second access node that performs wireless communication using a second radio access technology. In addition, the storage device 1j-30 provides the stored data in response to a request from the controller 1j-40.

[0116] The controller 1j-40 controls the overall operation of the UE. For example, the controller 1j-40 transmits and receives signals through the baseband processor 1j-20 and the RF processor 1j-10. In addition, the controller 1j-40 writes data to or reads data from the storage device 1j-30. To this end, the controller 1j-40 may include at least one processor. For example, the controller 1j-40 may include a communication processor (CP) for controlling communication and an application processor (AP) for controlling higher layers such as application programs.

[0117] Figure 11 is a block diagram showing the structure of a base station according to the present disclosure.

[0118] As shown in the figure, the base station includes an RF processor 1i-10, a baseband processor 1i-20, a backhaul communication unit 1i-30, a storage device 1i-40, and a controller 1i-50.

[0119] The RF processor 1i-10 performs functions for transmitting and receiving signals through a radio channel, such as signal band conversion and amplification. That is, the RF processor 1i-10 performs up-conversion of a baseband signal provided from the baseband processor 1i-20 to an RF band signal, transmits the converted signal through an antenna, and performs down-conversion of an RF band signal received through the antenna to a baseband signal. For example, the RF processor 1i-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, and an ADC.

[0120] Although only one antenna is shown in the drawings, multiple antennas may be provided for the base station. In addition, the RF processor 1i-10 may include multiple RF chains. In addition, the RF processor 1i-10 may perform beamforming. For beamforming, the RF processor 1i-10 may adjust the phase and amplitude of signals transmitted and received through multiple antennas or antenna elements. The RF processor 1i-10 may perform downlink MIMO operations by transmitting one or more layers.

[0121] The baseband processor 1i-20 performs conversion between a baseband signal and a bit string according to the physical layer specifications of the first radio access technology. For example, for data transmission, the baseband processor 1i-20 generates complex symbols by encoding and modulating the transmitted bit string. In addition, for data reception, the baseband processor 1i-20 recovers the received bit string by demodulating and decoding the baseband signal provided from the RF processor 1i-10. For example, in the case of using OFDM, for data transmission, the baseband processor 1i-20 generates complex symbols by encoding and modulating the transmitted bit string, maps the complex symbols to subcarriers, and forms an OFDM symbol through IFFT operation and CP insertion. In addition, for data reception, the baseband processor 1i-20 divides the baseband signal provided from the RF processor 1i-10 in units of OFDM symbols, recovers the signal mapped to the subcarriers through FFT operation, and recovers the received bit string through demodulation and decoding. As described above, the baseband processor 1i-20 and the RF processor 1i-10 transmit and receive signals. Therefore, the baseband processor 1i-20 and the RF processor 1i-10 may be referred to as a transmitter, a receiver, a transceiver, a communication unit, or a wireless communication unit.

[0122] The backhaul communication unit 1i-30 provides an interface for communicating with other nodes in the network. That is, the backhaul communication unit 1i-30 converts a bit string sent from the master base station to another node such as an auxiliary base station or a core network into a physical signal, and converts a physical signal received from another node into a bit string.

[0123] The storage device 1i-40 stores data such as basic programs, application programs, and configuration information for the operation of the master base station. In particular, the storage device 1i-40 can store information about the bearers allocated to the connected UEs and the measurement results reported from the connected UEs. In addition, the storage device 1i-40 can store information used as a criterion for determining whether to provide or suspend multi-connection to the UEs. Further, the storage device 1i-40 provides the stored data in response to a request from the controller 1i-50.

[0124] The controller 1i-50 controls the overall operation of the master base station. For example, the controller 1i-50 transmits and receives signals through the baseband processor 1i-20 and the RF processor 1i-10 or through the backhaul communication unit 1i-30. In addition, the controller 1i-50 writes data to or reads data from the storage device 1i-40. To this end, the controller 1i-50 may include at least one processor.

[0125] In the above embodiments of the present disclosure, the elements included in the present disclosure are expressed in singular or plural forms according to the specific embodiments proposed. However, for ease of description, the singular or plural expressions are appropriately selected according to the presented situations, and the present disclosure is not limited to a single element or multiple elements. Those elements described in the plural form may be configured as a single element, and those elements described in the singular form may be configured as multiple elements.

[0126] Meanwhile, the embodiments of the present disclosure disclosed in this specification and the drawings are provided as specific illustrations to facilitate the explanation of the technical content of the present disclosure and to help the understanding of the present disclosure, and are not intended to limit the scope of the present disclosure. That is, those skilled in the art should understand that many variations and modifications of the technical concepts described herein will still fall within the scope of the present disclosure. Additionally, the above embodiments can be executed in combination with each other as needed. For example, the base station and the terminal can be operated by combining some of the multiple embodiments of the present disclosure. Further, the embodiments of the present disclosure are also applicable to other communication systems, and other modifications based on the technical spirit of the embodiments can also be performed. For example, the embodiments can also be applied to LTE systems, 5G or NR systems, etc.

Claims

1. A method performed by a terminal in a wireless communication system, the method comprises: receiving, from a base station, first DRX configuration information for a first discontinuous reception (DRX) group and second DRX configuration information for a second DRX group; performing physical downlink control channel (PDCCH) monitoring for the first DRX group during a first active time based on the first DRX configuration information, and performing PDCCH monitoring for the second DRX group during a second active time based on the second DRX configuration information; receiving a media access control (MAC) control element (CE) associated with a DRX cycle in one of the first DRX group and the second DRX group; and using one DRX cycle for each of the first DRX group and the second DRX group based on the MAC CE, wherein the first DRX group and the second DRX group are determined based on a frequency range (FR).

2. The method according to claim 1, further comprises: stopping a timer when the timer is running in at least one of the first DRX group and the second DRX group, wherein the timer is one of a DRX inactivity timer or a DRX on-duration timer, wherein, when a short DRX cycle is configured based on the first DRX configuration, after receiving the MAC CE, starting a short-cycle timer for each of the first DRX group and the second DRX group.

3. The method according to claim 1, further comprises: identifying expiration of a DRX inactivity timer for at least one of the first DRX group and the second DRX group; and starting, after the expiration of the DRX inactivity timer, a short-cycle timer for at least one of the first DRX group and the second DRX group when a short DRX cycle is configured based on the first DRX configuration information.

4. The method according to claim 1, further comprises: sending, to the base station, capability information on whether the terminal supports the second DRX group, wherein the second DRX configuration information is received based on the capability information.

5. The method according to claim 1, further comprises: receiving, from the base station, configuration information on a serving cell; and identifying the DRX group to which the serving cell belongs based on the configuration information, wherein the second DRX configuration information includes information on a DRX on-duration timer and information on a DRX inactivity timer.

6. A method performed by a base station in a wireless communication system, the method comprises: sending, to a terminal, first DRX configuration information for a first discontinuous reception (DRX) group and second DRX configuration information for a second DRX group; Transmit a Physical Downlink Control Channel (PDCCH) for the first DRX group using a first active time based on the first DRX configuration information, and transmit a PDCCH for the second DRX group using a second active time based on the second DRX configuration information; And Transmit a Medium Access Control (MAC) control element (CE) associated with a DRX cycle for one of the first DRX group and the second DRX group, Wherein, based on the MAC CE, one DRX cycle is used for each of the first DRX group and the second DRX group, and Wherein, the first DRX group and the second DRX group are determined based on a frequency range (FR).

7. The method according to claim 6, Wherein, In the case where the first DRX configuration information includes information about a short DRX cycle, the one DRX cycle is a short DRX cycle, and Wherein, in the case where the first DRX configuration information does not include information about the short DRX cycle, the one DRX cycle is a long DRX cycle.

8. The method according to claim 6, further Comprising: Receive, from a terminal, capability information regarding whether the terminal supports the second DRX group, Wherein, the second DRX configuration information is transmitted based on the capability information, and Wherein, the second DRX configuration information includes information about a DRX on-duration timer (drx-ondurationtimer) and information about a DRX inactivity timer (drx-inactivitytimer).

9. A terminal in a wireless communication system, the terminal Comprising: A transceiver; And A controller configured to: Control the transceiver to receive first DRX configuration information for a first Discontinuous Reception (DRX) group and second DRX configuration information for a second DRX group from a base station; Perform monitoring of a Physical Downlink Control Channel (PDCCH) for the first DRX group during a first active time based on the first DRX configuration information, and perform monitoring of a PDCCH for the second DRX group during a second active time based on the second DRX configuration information; Control the transceiver to receive a Medium Access Control (MAC) control element (CE) associated with a DRX cycle in one of the first DRX group and the second DRX group; And Based on the MAC CE, use one DRX cycle for each of the first DRX group and the second DRX group, Wherein, the first DRX group and the second DRX group are determined based on a frequency range (FR).

10. The terminal according to claim 9, Wherein, The controller is further configured to stop the timer in the case where the timer is running in at least one of the first DRX group and the second DRX group, Wherein, the timer is one of a DRX inactivity timer (drx-inactivitytimer) or a DRX on-duration timer (drx-ondurationtimer), and Wherein, when the short DRX cycle is configured based on the first DRX configuration, after receiving the MAC CE, a short cycle timer is started for each of the first DRX group and the second DRX group.

11. The terminal according to claim 9, wherein, the controller is further configured to: identify that the DRX inactivity timer drx-inactivitytimer for at least one of the first DRX group and the second DRX group expires; and when the short DRX cycle is configured based on the first DRX configuration information, after the drx-inactivitytimer expires, start a short cycle timer for at least one of the first DRX group and the second DRX group.

12. The terminal according to claim 9, wherein, the controller is further configured to control the transceiver to send to the base station capability information on whether the terminal supports the second DRX group, and wherein, the second DRX configuration information is received based on the capability information.

13. The terminal according to claim 9, wherein, the controller is further configured to control the transceiver to receive from the base station configuration information on the serving cell, and identify the DRX group to which the serving cell belongs based on the configuration information, and wherein, the second DRX configuration information includes information on the DRX on-duration timer drx-ondurationtimer and information on the DRX inactivity timer drx-inactivitytimer.

14. A base station in a wireless communication system, the base station comprising: a transceiver; and a controller, configured to: control the transceiver to send to the terminal the first DRX configuration information for the first discontinuous reception DRX group and the second DRX configuration information for the second DRX group; control the transceiver to use a first active time to send a physical downlink control channel PDCCH for the first DRX group based on the first DRX configuration information, and use a second active time to send a PDCCH for the second DRX group based on the second DRX configuration information; and control the transceiver to send a media access control MAC control element CE associated with the DRX cycle for one of the first DRX group and the second DRX group, wherein, based on the MAC CE, one DRX cycle is used for each of the first DRX group and the second DRX group, and wherein, the first DRX group and the second DRX group are determined based on the frequency range FR.

15. The base station according to claim 14, wherein, when the first DRX configuration information includes information on the short DRX cycle, the one DRX cycle is the short DRX cycle, and wherein, when the first DRX configuration information does not include information on the short DRX cycle, the one DRX cycle is the long DRX cycle Wherein, the controller is further configured to control the transceiver to receive, from the terminal, capability information on whether the terminal supports a second DRX group, and to send second DRX configuration information based on the capability information, and Wherein, the second DRX configuration information includes information on a DRX on-duration timer drx-ondurationtimer and information on a DRX inactivity timer drx-inactivitytimer.

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