Patent Publication Number: US-2022225377-A1

Title: Method and apparatus for gap operation in wireless communication system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Pursuant to 35 U.S.C. § 119 (a), this application claims the benefit of Korean Patent Application No. 10-2021-0002735 filed on Jan. 8, 2021, the contents of which are all hereby incorporated by reference herein in their entirety. 
     BACKGROUND OF THE DISCLOSURE 
     Field of the Disclosure 
     The present disclosure relates to a gap operation in wireless communications. 
     Related Art 
     3rd generation partnership project (3GPP) long-term evolution (LTE) is a technology for enabling high-speed packet communications. Many schemes have been proposed for the LTE objective including those that aim to reduce user and provider costs, improve service quality, and expand and improve coverage and system capacity. The 3GPP LTE requires reduced cost per bit, increased service availability, flexible use of a frequency band, a simple structure, an open interface, and adequate power consumption of a terminal as an upper-level requirement. 
     Work has started in international telecommunication union (ITU) and 3GPP to develop requirements and specifications for new radio (NR) systems. 3GPP has to identify and develop the technology components needed for successfully standardizing the new RAT timely satisfying both the urgent market needs, and the more long-term requirements set forth by the ITU radio communication sector (ITU-R) international mobile telecommunications (IMT)-2020 process. Further, the NR should be able to use any spectrum band ranging at least up to 100 GHz that may be made available for wireless communications even in a more distant future. 
     The NR targets a single technical framework addressing all usage scenarios, requirements and deployment scenarios including enhanced mobile broadband (eMBB), massive machine-type-communications (mMTC), ultra-reliable and low latency communications (URLLC), etc. The NR shall be inherently forward compatible. 
     In wireless communications, a gap may refer to a duration in which a network does not schedule any data for a user equipment (UE), in order for the UE to perform other operations. For example, the gap may comprise a measurement gap in which the UE performs inter-frequency measurement. The gap may further comprise a scheduling gap in which the UE performs operations in another network. 
     SUMMARY OF THE DISCLOSURE 
     Technical Problem 
     An aspect of the present disclosure is to provide method and apparatus for a gap operation in a wireless communication system. 
     Another aspect of the present disclosure is to provide method and apparatus for a gap operation in a multi-universal identity subscriber module (multi-USIM, MUSIM) UE in a wireless communication system. 
     Technical Solution 
     According to an embodiment of the present disclosure, a method performed by a user equipment (UE) in a wireless communication system comprises: registering to both a first network and a second network; establishing a connection with the first network; transmitting, to the first network, preference information related to a scheduling gap for the second network; receiving, from the first network, a discontinuous reception (DRX) configuration configuring an inactive duration of a DRX cycle for the first network to include the scheduling gap for the second network; applying the inactive duration of the DRX cycle for the first network in the DRX configuration; and performing operations with the second network during the inactive duration of the DRX cycle for the first network, wherein the inactive duration of the DRX cycle for the first network is a duration in which the UE does not monitor a control channel from the first network, and wherein the scheduling gap for the second network is a duration in which the UE monitors a control channel from the second network. 
     According to an embodiment of the present disclosure, a user equipment (UE) in a wireless communication system comprises: a transceiver; a memory; and at least one processor operatively coupled to the transceiver and the memory, and configured to: register to both a first network and a second network; establish a connection with the first network; control the transceiver to transmit, to the first network, preference information related to a scheduling gap for the second network; control the transceiver to receive, from the first network, a discontinuous reception (DRX) configuration configuring an inactive duration of a DRX cycle for the first network to include the scheduling gap for the second network; apply the inactive duration of the DRX cycle for the first network in the DRX configuration; and perform operations with the second network during the inactive duration of the DRX cycle for the first network, wherein the inactive duration of the DRX cycle for the first network is a duration in which the UE does not monitor a control channel from the first network, and wherein the scheduling gap for the second network is a duration in which the UE monitors a control channel from the second network. 
     According to an embodiment of the present disclosure, a non-transitory computer-readable medium (CRM) having stored thereon a plurality of instructions is provided. The plurality of instructions, when executed by a processor of a user equipment (UE), cause the UE to: register to both a first network and a second network; establish a connection with the first network; transmit, to the first network, preference information related to a scheduling gap for the second network; receive, from the first network, a discontinuous reception (DRX) configuration configuring an inactive duration of a DRX cycle for the first network to include the scheduling gap for the second network; apply the inactive duration of the DRX cycle for the first network in the DRX configuration; and perform operations with the second network during the inactive duration of the DRX cycle for the first network, wherein the inactive duration of the DRX cycle for the first network is a duration in which the UE does not monitor a control channel from the first network, and wherein the scheduling gap for the second network is a duration in which the UE monitors a control channel from the second network. 
     According to an embodiment of the present disclosure, a processor for a user equipment (UE) in a wireless communication system is provided. A memory of the UE stores a software code which implements instructions that, when executed by the processor, perform operations comprising: registering to both a first network and a second network; establishing a connection with the first network; transmitting, to the first network, preference information related to a scheduling gap for the second network; receiving, from the first network, a discontinuous reception (DRX) configuration configuring an inactive duration of a DRX cycle for the first network to include the scheduling gap for the second network; applying the inactive duration of the DRX cycle for the first network in the DRX configuration; and performing operations with the second network during the inactive duration of the DRX cycle for the first network, wherein the inactive duration of the DRX cycle for the first network is a duration in which the UE does not monitor a control channel from the first network, and wherein the scheduling gap for the second network is a duration in which the UE monitors a control channel from the second network. 
     According to an embodiment of the present disclosure, a method performed by a base station (BS) in a first network in a wireless communication system comprises: performing at least part of a procedure for registering a user equipment (UE) in the first network and a second network; establishing a connection with the UE; receiving, from the UE, preference information related to a scheduling gap for the second network; and transmitting, to the UE, a discontinuous reception (DRX) configuration configuring an inactive duration of a DRX cycle for the first network to include the scheduling gap for the second network, wherein the inactive duration of the DRX cycle for the first network is a duration in which the UE does not monitor a control channel from the first network, and wherein the scheduling gap for the second network is a duration in which the UE monitors a control channel from the second network. 
     According to an embodiment of the present disclosure, a base station (BS) in a first network in a wireless communication system comprises: a transceiver; a memory; and at least one processor operatively coupled to the transceiver and the memory, and configured to: perform at least part of a procedure for registering a user equipment (UE) in the first network and a second network; establish a connection with the UE; control the transceiver to receive, from the UE, preference information related to a scheduling gap for the second network; and control the transceiver to transmit, to the UE, a discontinuous reception (DRX) configuration configuring an inactive duration of a DRX cycle for the first network to include the scheduling gap for the second network, wherein the inactive duration of the DRX cycle for the first network is a duration in which the UE does not monitor a control channel from the first network, and wherein the scheduling gap for the second network is a duration in which the UE monitors a control channel from the second network. 
     Advantageous Effect 
     The present disclosure can have various advantageous effects. 
     For example, the unnecessary duration can be reduced by configuring overlapped duration for CDRX and the scheduling gap so that more efficient data scheduling is possible for MUSIM UE. Also, since the UE sends the network new information indicating a preference that the DRX is used for the scheduling gap, the network can provide the UE&#39;s preference on the DRX configuration without rejection to support quick SIM switching. 
     Advantageous effects which can be obtained through specific embodiments of the present disclosure are not limited to the advantageous effects listed above. For example, there may be a variety of technical effects that a person having ordinary skill in the related art can understand and/or derive from the present disclosure. Accordingly, the specific effects of the present disclosure are not limited to those explicitly described herein, but may include various effects that may be understood or derived from the technical features of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows examples of 5G usage scenarios to which the technical features of the present disclosure can be applied. 
         FIG. 2  shows an example of a wireless communication system to which the technical features of the present disclosure can be applied. 
         FIG. 3  shows an example of a wireless communication system to which the technical features of the present disclosure can be applied. 
         FIG. 4  shows another example of a wireless communication system to which the technical features of the present disclosure can be applied. 
         FIG. 5  shows a block diagram of a user plane protocol stack to which the technical features of the present disclosure can be applied. 
         FIG. 6  shows a block diagram of a control plane protocol stack to which the technical features of the present disclosure can be applied. 
         FIG. 7  illustrates a frame structure in a 3GPP based wireless communication system. 
         FIG. 8  illustrates a data flow example in the 3GPP NR system. 
         FIG. 9  shows an example of a discontinuous reception (DRX) operation to which technical feature of the present disclosure can be applied. 
         FIG. 10  shows an example of a wireless environment in which a MUSIM device operates according to an embodiment of the present disclosure. 
         FIG. 11  shows an example of a method performed by a UE according to an embodiment of the present disclosure. 
         FIG. 12  shows an example of a method performed by a BS in a first network according to an embodiment of the present disclosure. 
         FIG. 13  shows an example of a method for implementing CDRX based scheduling gap in MUSIM according to an embodiment of the present disclosure. 
         FIG. 14  shows a UE to implement an embodiment of the present disclosure. 
         FIG. 15  shows another example of a wireless communication system to which the technical features of the present disclosure can be applied. 
         FIG. 16  shows an example of an AI device to which the technical features of the present disclosure can be applied. 
         FIG. 17  shows an example of an AI system to which the technical features of the present disclosure can be applied. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The technical features described below may be used by a communication standard by the 3rd generation partnership project (3GPP) standardization organization, a communication standard by the institute of electrical and electronics engineers (IEEE), etc. For example, the communication standards by the 3GPP standardization organization include long-term evolution (LTE) and/or evolution of LTE systems. The evolution of LTE systems includes LTE-advanced (LTE-A), LTE-A Pro, and/or 5G new radio (NR). The communication standard by the IEEE standardization organization includes a wireless local area network (WLAN) system such as IEEE 802.11a/b/g/n/ac/ax. The above system uses various multiple access technologies such as orthogonal frequency division multiple access (OFDMA) and/or single carrier frequency division multiple access (SC-FDMA) for downlink (DL) and/or uplink (UL). For example, only OFDMA may be used for DL and only SC-FDMA may be used for UL. Alternatively, OFDMA and SC-FDMA may be used for DL and/or UL. 
     In the present disclosure, “A or B” may mean “only A”, “only B”, or “both A and B”. In other words, “A or B” in the present disclosure may be interpreted as “A and/or B”. For example, “A, B or C” in the present disclosure may mean “only A”, “only B”, “only C”, or “any combination of A, B and C”. 
     In the present disclosure, slash (/) or comma (,) may mean “and/or”. For example, “A/B” may mean “A and/or B”. Accordingly, “A/B” may mean “only A”, “only B”, or “both A and B”. For example, “A, B, C” may mean “A, B or C”. 
     In the present disclosure, “at least one of A and B” may mean “only A”, “only B” or “both A and B”. In addition, the expression “at least one of A or B” or “at least one of A and/or B” in the present disclosure may be interpreted as same as “at least one of A and B”. 
     In addition, in the present disclosure, “at least one of A, B and C” may mean “only A”, “only B”, “only C”, or “any combination of A, B and C”. In addition, “at least one of A, B or C” or “at least one of A, B and/or C” may mean “at least one of A, B and C”. 
     Also, parentheses used in the present disclosure may mean “for example”. In detail, when it is shown as “control information (PDCCH)”, “PDCCH” may be proposed as an example of “control information”. In other words, “control information” in the present disclosure is not limited to “PDCCH”, and “PDDCH” may be proposed as an example of “control information”. In addition, even when shown as “control information (i.e., PDCCH)”, “PDCCH” may be proposed as an example of “control information”. 
     Technical features that are separately described in one drawing in the present disclosure may be implemented separately or simultaneously. 
     Throughout the disclosure, the terms ‘radio access network (RAN) node’, ‘base station’, ‘eNB’, ‘gNB’ and ‘cell’ may be used interchangeably. Further, a UE may be a kind of a wireless device, and throughout the disclosure, the terms ‘UE’ and ‘wireless device’ may be used interchangeably. 
     Throughout the disclosure, the terms ‘cell quality’, ‘signal strength’, ‘signal quality’, ‘channel state’, ‘channel quality’, ‘ channel state/reference signal received power (RSRP)’ and ‘ reference signal received quality (RSRQ)’ may be used interchangeably. 
     The following drawings are created to explain specific embodiments of the present disclosure. The names of the specific devices or the names of the specific signals/messages/fields shown in the drawings are provided by way of example, and thus the technical features of the present disclosure are not limited to the specific names used in the following drawings. 
       FIG. 1  shows examples of 5G usage scenarios to which the technical features of the present disclosure can be applied. 
     The 5G usage scenarios shown in  FIG. 1  are only exemplary, and the technical features of the present disclosure can be applied to other 5G usage scenarios which are not shown in  FIG. 1 . 
     Referring to  FIG. 1 , the three main requirements areas of 5G include (1) enhanced mobile broadband (eMBB) domain, (2) massive machine type communication (mMTC) area, and (3) ultra-reliable and low latency communications (URLLC) area. Some use cases may require multiple areas for optimization and, other use cases may only focus on only one key performance indicator (KPI). 5G is to support these various use cases in a flexible and reliable way. 
     eMBB focuses on across-the-board enhancements to the data rate, latency, user density, capacity and coverage of mobile broadband access. The eMBB aims ˜10 Gbps of throughput. eMBB far surpasses basic mobile Internet access and covers rich interactive work and media and entertainment applications in cloud and/or augmented reality. Data is one of the key drivers of 5G and may not be able to see dedicated voice services for the first time in the 5G era. In 5G, the voice is expected to be processed as an application simply using the data connection provided by the communication system. The main reason for the increased volume of traffic is an increase in the size of the content and an increase in the number of applications requiring high data rates. Streaming services (audio and video), interactive video and mobile Internet connectivity will become more common as more devices connect to the Internet. Many of these applications require always-on connectivity to push real-time information and notifications to the user. Cloud storage and applications are growing rapidly in mobile communication platforms, which can be applied to both work and entertainment. Cloud storage is a special use case that drives growth of uplink data rate. 5G is also used for remote tasks on the cloud and requires much lower end-to-end delay to maintain a good user experience when the tactile interface is used. In entertainment, for example, cloud games and video streaming are another key factor that increases the demand for mobile broadband capabilities. Entertainment is essential in smartphones and tablets anywhere, including high mobility environments such as trains, cars and airplanes. Another use case is augmented reality and information retrieval for entertainment. Here, augmented reality requires very low latency and instantaneous data amount. 
     mMTC is designed to enable communication between devices that are low-cost, massive in number and battery-driven, intended to support applications such as smart metering, logistics, and field and body sensors. mMTC aims ˜10 years on battery and/or ˜1 million devices/km2. mMTC allows seamless integration of embedded sensors in all areas and is one of the most widely used 5G applications. Potentially by 2020, internet-of-things (IoT) devices are expected to reach 20.4 billion. Industrial IoT is one of the areas where 5G plays a key role in enabling smart cities, asset tracking, smart utilities, agriculture and security infrastructures. 
     URLLC will make it possible for devices and machines to communicate with ultra-reliability, very low latency and high availability, making it ideal for vehicular communication, industrial control, factory automation, remote surgery, smart grids and public safety applications. URLLC aims ˜1 ms of latency. URLLC includes new services that will change the industry through links with ultra-reliability/low latency, such as remote control of key infrastructure and self-driving vehicles. The level of reliability and latency is essential for smart grid control, industrial automation, robotics, drones control and coordination. 
     Next, a plurality of use cases included in the triangle of  FIG. 1  will be described in more detail. 
     5G can complement fiber-to-the-home (FTTH) and cable-based broadband (or DOCSIS) as a means of delivering streams rated from hundreds of megabits per second to gigabits per second. This high speed can be required to deliver TVs with resolutions of 4K or more (6K, 8K and above) as well as virtual reality (VR) and augmented reality (AR). VR and AR applications include mostly immersive sporting events. Certain applications may require special network settings. For example, in the case of a VR game, a game company may need to integrate a core server with an edge network server of a network operator to minimize delay. 
     Automotive is expected to become an important new driver for 5G, with many use cases for mobile communications to vehicles. For example, entertainment for passengers demands high capacity and high mobile broadband at the same time. This is because future users will continue to expect high-quality connections regardless of their location and speed. Another use case in the automotive sector is an augmented reality dashboard. The driver can identify an object in the dark on top of what is being viewed through the front window through the augmented reality dashboard. The augmented reality dashboard displays information that will inform the driver about the object&#39;s distance and movement. In the future, the wireless module enables communication between vehicles, information exchange between the vehicle and the supporting infrastructure, and information exchange between the vehicle and other connected devices (e.g. devices accompanied by a pedestrian). The safety system allows the driver to guide the alternative course of action so that he can drive more safely, thereby reducing the risk of accidents. The next step will be a remotely controlled vehicle or self-driving vehicle. This requires a very reliable and very fast communication between different self-driving vehicles and between vehicles and infrastructure. In the future, a self-driving vehicle will perform all driving activities, and the driver will focus only on traffic that the vehicle itself cannot identify. The technical requirements of self-driving vehicles require ultra-low latency and high-speed reliability to increase traffic safety to a level not achievable by humans. 
     Smart cities and smart homes, which are referred to as smart societies, will be embedded in high density wireless sensor networks. The distributed network of intelligent sensors will identify conditions for cost and energy-efficient maintenance of a city or house. A similar setting can be performed for each home. Temperature sensors, windows and heating controllers, burglar alarms and appliances are all wirelessly connected. Many of these sensors typically require low data rate, low power and low cost. However, for example, real-time high-definition (HD) video may be required for certain types of devices for monitoring. 
     The consumption and distribution of energy, including heat or gas, is highly dispersed, requiring automated control of distributed sensor networks. The smart grid interconnects these sensors using digital information and communication technologies to collect and act on information. This information can include supplier and consumer behavior, allowing the smart grid to improve the distribution of fuel, such as electricity, in terms of efficiency, reliability, economy, production sustainability, and automated methods. The smart grid can be viewed as another sensor network with low latency. 
     The health sector has many applications that can benefit from mobile communications. Communication systems can support telemedicine to provide clinical care in remote locations. This can help to reduce barriers to distance and improve access to health services that are not continuously available in distant rural areas. It is also used to save lives in critical care and emergency situations. Mobile communication based wireless sensor networks can provide remote monitoring and sensors for parameters such as heart rate and blood pressure. 
     Wireless and mobile communications are becoming increasingly important in industrial applications. Wiring costs are high for installation and maintenance. Thus, the possibility of replacing a cable with a wireless link that can be reconfigured is an attractive opportunity in many industries. However, achieving this requires that wireless connections operate with similar delay, reliability, and capacity as cables and that their management is simplified. Low latency and very low error probabilities are new requirements that need to be connected to 5G. 
     Logistics and freight tracking are important use cases of mobile communications that enable tracking of inventory and packages anywhere using location based information systems. Use cases of logistics and freight tracking typically require low data rates, but require a large range and reliable location information. 
     NR supports multiple numerology (or, subcarrier spacing (SCS)) to support various 5G services. For example, when the SCS is 15 kHz, wide area in traditional cellular bands may be supported. When the SCS is 30 kHz/60 kHz, dense-urban, lower latency and wider carrier bandwidth may be supported. When the SCS is 60 kHz or higher, a bandwidth greater than 24.25 GHz may be supported to overcome phase noise. 
     The NR frequency band may be defined as two types of frequency range, i.e., FR1 and FR2. The numerical value of the frequency range may be changed. For example, the frequency ranges of the two types (FR1 and FR2) may be as shown in Table 1 below. For ease of explanation, in the frequency ranges used in the NR system, FR1 may mean “sub 6 GHz range”, FR2 may mean “above 6 GHz range,” and may be referred to as millimeter wave (mmW). 
     
       
         
           
               
               
               
             
               
                   
               
               
                 Frequency Range 
                 Corresponding frequency 
                   
               
               
                 designation 
                 range 
                 Subcarrier Spacing 
               
               
                   
               
             
            
               
                 FR1 
                   450 MHz-6000 MHz 
                   15, 30, 60 kHz 
               
               
                 FR2 
                 24250 MHz-52600 MHz 
                 60, 120, 240 kHz 
               
               
                   
               
            
           
         
       
     
     As mentioned above, the numerical value of the frequency range of the NR system may be changed. For example, FR1 may include a frequency band of 410 MHz to 7125 MHz as shown in Table 2 below. That is, FR1 may include a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or more. For example, a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or more included in FR1 may include an unlicensed band. Unlicensed bands may be used for a variety of purposes, for example for communication for vehicles (e.g., autonomous driving). 
     
       
         
           
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Frequency Range 
                 Corresponding frequency 
                   
               
               
                 designation 
                 range 
                 Subcarrier Spacing 
               
               
                   
               
             
            
               
                 FR1 
                   410 MHz-7125 MHz 
                   15, 30, 60 kHz 
               
               
                 FR2 
                 24250 MHz-52600 MHz 
                 60, 120, 240 kHz 
               
               
                   
               
            
           
         
       
     
       FIG. 2  shows an example of a wireless communication system to which the technical features of the present disclosure can be applied. 
     Referring to  FIG. 2 , the wireless communication system may include a first device  210  and a second device  220 . 
     The first device  210  includes a base station, a network node, a transmitting UE, a receiving UE, a wireless device, a wireless communication device, a vehicle, a vehicle equipped with an autonomous driving function, a connected car, a drone, an unmanned aerial vehicle (UAV), an artificial intelligence (AI) module, a robot, an AR device, a VR device, a mixed reality (MR) device, a hologram device, a public safety device, an MTC device, an IoT device, a medical device, a fin-tech device (or, a financial device), a security device, a climate/environmental device, a device related to 5G services, or a device related to the fourth industrial revolution. 
     The second device  220  includes a base station, a network node, a transmitting UE, a receiving UE, a wireless device, a wireless communication device, a vehicle, a vehicle equipped with an autonomous driving function, a connected car, a drone, a UAV, an AI module, a robot, an AR device, a VR device, an MR device, a hologram device, a public safety device, an MTC device, an IoT device, a medical device, a fin-tech device (or, a financial device), a security device, a climate/environmental device, a device related to 5G services, or a device related to the fourth industrial revolution. 
     For example, the UE may include a mobile phone, a smart phone, a laptop computer, a digital broadcasting terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation device, a slate personal computer (PC), a tablet PC, an ultrabook, a wearable device (e.g. a smartwatch, a smart glass, a head mounted display (HMD)). For example, the HMD may be a display device worn on the head. For example, the HMD may be used to implement AR, VR and/or MR. 
     For example, the drone may be a flying object that is flying by a radio control signal without a person boarding it. For example, the VR device may include a device that implements an object or background in the virtual world. For example, the AR device may include a device that implements connection of an object and/or a background of a virtual world to an object and/or a background of the real world. For example, the MR device may include a device that implements fusion of an object and/or a background of a virtual world to an object and/or a background of the real world. For example, the hologram device may include a device that implements a 360-degree stereoscopic image by recording and playing stereoscopic information by utilizing a phenomenon of interference of light generated by the two laser lights meeting with each other, called holography. For example, the public safety device may include a video relay device or a video device that can be worn by the user&#39;s body. For example, the MTC device and the IoT device may be a device that do not require direct human intervention or manipulation. For example, the MTC device and the IoT device may include a smart meter, a vending machine, a thermometer, a smart bulb, a door lock and/or various sensors. For example, the medical device may be a device used for the purpose of diagnosing, treating, alleviating, handling, or preventing a disease. For example, the medical device may be a device used for the purpose of diagnosing, treating, alleviating, or correcting an injury or disorder. For example, the medical device may be a device used for the purpose of inspecting, replacing or modifying a structure or function. For example, the medical device may be a device used for the purpose of controlling pregnancy. For example, the medical device may include a treatment device, a surgical device, an (in vitro) diagnostic device, a hearing aid and/or a procedural device, etc. For example, a security device may be a device installed to prevent the risk that may occur and to maintain safety. For example, the security device may include a camera, a closed-circuit TV (CCTV), a recorder, or a black box. For example, the fin-tech device may be a device capable of providing financial services such as mobile payment. For example, the fin-tech device may include a payment device or a point of sales (POS). For example, the climate/environmental device may include a device for monitoring or predicting the climate/environment. 
     The first device  210  may include at least one or more processors, such as a processor  211 , at least one memory, such as a memory  212 , and at least one transceiver, such as a transceiver  213 . The processor  211  may perform the functions, procedures, and/or methods of the first device described throughout the disclosure. The processor  211  may perform one or more protocols. For example, the processor  211  may perform one or more layers of the air interface protocol. The memory  212  is connected to the processor  211  and may store various types of information and/or instructions. The transceiver  213  is connected to the processor  211  and may be controlled by the processor  211  to transmit and receive wireless signals. 
     The second device  220  may include at least one or more processors, such as a processor  221 , at least one memory, such as a memory  222 , and at least one transceiver, such as a transceiver  223 . The processor  221  may perform the functions, procedures, and/or methods of the second device  220  described throughout the disclosure. The processor  221  may perform one or more protocols. For example, the processor  221  may perform one or more layers of the air interface protocol. The memory  222  is connected to the processor  221  and may store various types of information and/or instructions. The transceiver  223  is connected to the processor  221  and may be controlled by the processor  221  to transmit and receive wireless signals. 
     The memory  212 ,  222  may be connected internally or externally to the processor  211 ,  212 , or may be connected to other processors via a variety of technologies such as wired or wireless connections. 
     The first device  210  and/or the second device  220  may have more than one antenna. For example, antenna  214  and/or antenna  224  may be configured to transmit and receive wireless signals. 
       FIG. 3  shows an example of a wireless communication system to which the technical features of the present disclosure can be applied. 
     Specifically,  FIG. 3  shows a system architecture based on an evolved-UMTS terrestrial radio access network (E-UTRAN). The aforementioned LTE is a part of an evolved-UTMS (e-UMTS) using the E-UTRAN. 
     Referring to  FIG. 3 , the wireless communication system includes one or more user equipment (UE)  310 , an E-UTRAN and an evolved packet core (EPC). The UE  310  refers to a communication equipment carried by a user. The UE  310  may be fixed or mobile. The UE  310  may be referred to as another terminology, such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), a wireless device, etc. 
     The E-UTRAN consists of one or more evolved NodeB (eNB)  320 . The eNB  320  provides the E-UTRA user plane and control plane protocol terminations towards the UE  10 . The eNB  320  is generally a fixed station that communicates with the UE  310 . The eNB  320  hosts the functions, such as inter-cell radio resource management (RRM), radio bearer (RB) control, connection mobility control, radio admission control, measurement configuration/provision, dynamic resource allocation (scheduler), etc. The eNB  320  may be referred to as another terminology, such as a base station (BS), a base transceiver system (BTS), an access point (AP), etc. 
     A downlink (DL) denotes communication from the eNB  320  to the UE  310 . An uplink (UL) denotes communication from the UE  310  to the eNB  320 . A sidelink (SL) denotes communication between the UEs  310 . In the DL, a transmitter may be a part of the eNB  320 , and a receiver may be a part of the UE  310 . In the UL, the transmitter may be a part of the UE  310 , and the receiver may be a part of the eNB  320 . In the SL, the transmitter and receiver may be a part of the UE  310 . 
     The EPC includes a mobility management entity (MME), a serving gateway (S-GW) and a packet data network (PDN) gateway (P-GW). The MME hosts the functions, such as non-access stratum (NAS) security, idle state mobility handling, evolved packet system (EPS) bearer control, etc. The S-GW hosts the functions, such as mobility anchoring, etc. The S-GW is a gateway having an E-UTRAN as an endpoint. For convenience, MME/S-GW  330  will be referred to herein simply as a “gateway,” but it is understood that this entity includes both the MME and S-GW. The P-GW hosts the functions, such as UE Internet protocol (IP) address allocation, packet filtering, etc. The P-GW is a gateway having a PDN as an endpoint. The P-GW is connected to an external network. 
     The UE  310  is connected to the eNB  320  by means of the Uu interface. The UEs  310  are interconnected with each other by means of the PC5 interface. The eNBs  320  are interconnected with each other by means of the X2 interface. The eNBs  320  are also connected by means of the S1 interface to the EPC, more specifically to the MME by means of the S1-MME interface and to the S-GW by means of the S1-U interface. The S1 interface supports a many-to-many relation between MMEs/S-GWs and eNBs. 
       FIG. 4  shows another example of a wireless communication system to which the technical features of the present disclosure can be applied. 
     Specifically,  FIG. 4  shows a system architecture based on a 5G NR. The entity used in the 5G NR (hereinafter, simply referred to as “NR”) may absorb some or all of the functions of the entities introduced in  FIG. 3  (e.g. eNB, MME, S-GW). The entity used in the NR may be identified by the name “NG” for distinction from the LTE/LTE-A. 
     Referring to  FIG. 4 , the wireless communication system includes one or more UE  410 , a next-generation RAN (NG-RAN) and a 5th generation core network (5GC). The NG-RAN consists of at least one NG-RAN node. The NG-RAN node is an entity corresponding to the eNB  320  shown in  FIG. 3 . The NG-RAN node consists of at least one gNB  421  and/or at least one ng-eNB  422 . The gNB  421  provides NR user plane and control plane protocol terminations towards the UE  410 . The ng-eNB  422  provides E-UTRA user plane and control plane protocol terminations towards the UE  410 . 
     The 5GC includes an access and mobility management function (AMF), a user plane function (UPF) and a session management function (SMF). The AMF hosts the functions, such as NAS security, idle state mobility handling, etc. The AMF is an entity including the functions of the conventional MME. The UPF hosts the functions, such as mobility anchoring, protocol data unit (PDU) handling. The UPF an entity including the functions of the conventional  5 -GW. The SMF hosts the functions, such as UE IP address allocation, PDU session control. 
     The gNBs  421  and ng-eNBs  422  are interconnected with each other by means of the Xn interface. The gNBs  421  and ng-eNBs  422  are also connected by means of the NG interfaces to the 5GC, more specifically to the AMF by means of the NG-C interface and to the UPF by means of the NG-U interface. 
     A protocol structure between network entities described above is described. On the system of  FIG. 3  and/or  FIG. 4 , layers of a radio interface protocol between the UE and the network (e.g. NG-RAN and/or E-UTRAN) may be classified into a first layer (L1), a second layer (L2), and a third layer (L3) based on the lower three layers of the open system interconnection (OSI) model that is well-known in the communication system. 
       FIG. 5  shows a block diagram of a user plane protocol stack to which the technical features of the present disclosure can be applied.  FIG. 6  shows a block diagram of a control plane protocol stack to which the technical features of the present disclosure can be applied. 
     The user/control plane protocol stacks shown in  FIG. 5  and  FIG. 6  are used in NR. However, user/control plane protocol stacks shown in  FIG. 5  and  FIG. 6  may be used in LTE/LTE-A without loss of generality, by replacing gNB/AMF with eNB/MME. 
     Referring to  FIG. 5  and  FIG. 6 , a physical (PHY) layer belonging to L1. The PHY layer offers information transfer services to media access control (MAC) sublayer and higher layers. The PHY layer offers to the MAC sublayer transport channels. Data between the MAC sublayer and the PHY layer is transferred via the transport channels. Between different PHY layers, i.e., between a PHY layer of a transmission side and a PHY layer of a reception side, data is transferred via the physical channels. 
     The MAC sublayer belongs to L2. The main services and functions of the MAC sublayer include mapping between logical channels and transport channels, multiplexing/de-multiplexing of MAC service data units (SDUs) belonging to one or different logical channels into/from transport blocks (TB) delivered to/from the physical layer on transport channels, scheduling information reporting, error correction through hybrid automatic repeat request (HARQ), priority handling between UEs by means of dynamic scheduling, priority handling between logical channels of one UE by means of logical channel prioritization (LCP), etc. The MAC sublayer offers to the radio link control (RLC) sublayer logical channels. 
     The RLC sublayer belong to L2. The RLC sublayer supports three transmission modes, i.e. transparent mode (TM), unacknowledged mode (UM), and acknowledged mode (AM), in order to guarantee various quality of services (QoS) required by radio bearers. The main services and functions of the RLC sublayer depend on the transmission mode. For example, the RLC sublayer provides transfer of upper layer PDUs for all three modes, but provides error correction through ARQ for AM only. In LTE/LTE-A, the RLC sublayer provides concatenation, segmentation and reassembly of RLC SDUs (only for UM and AM data transfer) and re-segmentation of RLC data PDUs (only for AM data transfer). In NR, the RLC sublayer provides segmentation (only for AM and UM) and re-segmentation (only for AM) of RLC SDUs and reassembly of SDU (only for AM and UM). That is, the NR does not support concatenation of RLC SDUs. The RLC sublayer offers to the packet data convergence protocol (PDCP) sublayer RLC channels. 
     The PDCP sublayer belong to L2. The main services and functions of the PDCP sublayer for the user plane include header compression and decompression, transfer of user data, duplicate detection, PDCP PDU routing, retransmission of PDCP SDUs, ciphering and deciphering, etc. The main services and functions of the PDCP sublayer for the control plane include ciphering and integrity protection, transfer of control plane data, etc. 
     The service data adaptation protocol (SDAP) sublayer belong to L2. The SDAP sublayer is only defined in the user plane. The SDAP sublayer is only defined for NR. The main services and functions of SDAP include, mapping between a QoS flow and a data radio bearer (DRB), and marking QoS flow ID (QFI) in both DL and UL packets. The SDAP sublayer offers to 5GC QoS flows. 
     A radio resource control (RRC) layer belongs to L3. The RRC layer is only defined in the control plane. The RRC layer controls radio resources between the UE and the network. To this end, the RRC layer exchanges RRC messages between the UE and the BS. The main services and functions of the RRC layer include broadcast of system information related to AS and NAS, paging, establishment, maintenance and release of an RRC connection between the UE and the network, security functions including key management, establishment, configuration, maintenance and release of radio bearers, mobility functions, QoS management functions, UE measurement reporting and control of the reporting, NAS message transfer to/from NAS from/to UE. 
     In other words, the RRC layer controls logical channels, transport channels, and physical channels in relation to the configuration, reconfiguration, and release of radio bearers. A radio bearer refers to a logical path provided by L1 (PHY layer) and L2 (MAC/RLC/PDCP/SDAP sublayer) for data transmission between a UE and a network. Setting the radio bearer means defining the characteristics of the radio protocol layer and the channel for providing a specific service, and setting each specific parameter and operation method. Radio bearer may be divided into signaling RB (SRB) and data RB (DRB). The SRB is used as a path for transmitting RRC messages in the control plane, and the DRB is used as a path for transmitting user data in the user plane. 
     An RRC state indicates whether an RRC layer of the UE is logically connected to an RRC layer of the E-UTRAN. In LTE/LTE-A, when the RRC connection is established between the RRC layer of the UE and the RRC layer of the E-UTRAN, the UE is in the RRC connected state (RRC_CONNECTED). Otherwise, the UE is in the RRC idle state (RRC_IDLE). In NR, the RRC inactive state (RRC_INACTIVE) is additionally introduced. RRC_INACTIVE may be used for various purposes. For example, the massive machine type communications (MMTC) UEs can be efficiently managed in RRC_INACTIVE. When a specific condition is satisfied, transition is made from one of the above three states to the other. 
     A predetermined operation may be performed according to the RRC state. In RRC_IDLE, public land mobile network (PLMN) selection, broadcast of system information (SI), cell re-selection mobility, core network (CN) paging and discontinuous reception (DRX) configured by NAS may be performed. The UE shall have been allocated an identifier (ID) which uniquely identifies the UE in a tracking area. No RRC context stored in the BS. 
     In RRC_CONNECTED, the UE has an RRC connection with the network (i.e. E-UTRAN/NG-RAN). Network-CN connection (both C/U-planes) is also established for UE. The UE AS context is stored in the network and the UE. The RAN knows the cell which the UE belongs to. The network can transmit and/or receive data to/from UE. Network controlled mobility including measurement is also performed. 
     Most of operations performed in RRC_IDLE may be performed in RRC_INACTIVE. But, instead of CN paging in RRC_IDLE, RAN paging is performed in RRC_INACTIVE. In other words, in RRC_IDLE, paging for mobile terminated (MT) data is initiated by core network and paging area is managed by core network. In RRC_INACTIVE, paging is initiated by NG-RAN, and RAN-based notification area (RNA) is managed by NG-RAN. Further, instead of DRX for CN paging configured by NAS in RRC_IDLE, DRX for RAN paging is configured by NG-RAN in RRC_INACTIVE. Meanwhile, in RRC_INACTIVE, 5GC-NG-RAN connection (both C/U-planes) is established for UE, and the UE AS context is stored in NG-RAN and the UE. NG-RAN knows the RNA which the UE belongs to. 
     NAS layer is located at the top of the RRC layer. The NAS control protocol performs the functions, such as authentication, mobility management, security control. 
     The physical channels may be modulated according to OFDM processing and utilizes time and frequency as radio resources. The physical channels consist of a plurality of orthogonal frequency division multiplexing (OFDM) symbols in time domain and a plurality of subcarriers in frequency domain. One subframe consists of a plurality of OFDM symbols in the time domain. A resource block is a resource allocation unit, and consists of a plurality of OFDM symbols and a plurality of subcarriers. In addition, each subframe may use specific subcarriers of specific OFDM symbols (e.g. first OFDM symbol) of the corresponding subframe for a physical downlink control channel (PDCCH), i.e. L1/L2 control channel. A transmission time interval (TTI) is a basic unit of time used by a scheduler for resource allocation. The TTI may be defined in units of one or a plurality of slots, or may be defined in units of mini-slots. 
     The transport channels are classified according to how and with what characteristics data are transferred over the radio interface. DL transport channels include a broadcast channel (BCH) used for transmitting system information, a downlink shared channel (DL-SCH) used for transmitting user traffic or control signals, and a paging channel (PCH) used for paging a UE. UL transport channels include an uplink shared channel (UL-SCH) for transmitting user traffic or control signals and a random access channel (RACH) normally used for initial access to a cell. 
     Different kinds of data transfer services are offered by MAC sublayer. Each logical channel type is defined by what type of information is transferred. Logical channels are classified into two groups: control channels and traffic channels. 
     Control channels are used for the transfer of control plane information only. The control channels include a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH) and a dedicated control channel (DCCH). The BCCH is a DL channel for broadcasting system control information. The PCCH is DL channel that transfers paging information, system information change notifications. The CCCH is a channel for transmitting control information between UEs and network. This channel is used for UEs having no RRC connection with the network. The DCCH is a point-to-point bi-directional channel that transmits dedicated control information between a UE and the network. This channel is used by UEs having an RRC connection. 
     Traffic channels are used for the transfer of user plane information only. The traffic channels include a dedicated traffic channel (DTCH). The DTCH is a point-to-point channel, dedicated to one UE, for the transfer of user information. The DTCH can exist in both UL and DL. 
     Regarding mapping between the logical channels and transport channels, in DL, BCCH can be mapped to BCH, BCCH can be mapped to DL-SCH, PCCH can be mapped to PCH, CCCH can be mapped to DL-SCH, DCCH can be mapped to DL-SCH, and DTCH can be mapped to DL-SCH. In UL, CCCH can be mapped to UL-SCH, DCCH can be mapped to UL-SCH, and DTCH can be mapped to UL-SCH. 
       FIG. 7  illustrates a frame structure in a 3GPP based wireless communication system. 
     The frame structure illustrated in  FIG. 7  is purely exemplary and the number of subframes, the number of slots, and/or the number of symbols in a frame may be variously changed. In the 3GPP based wireless communication system, an OFDM numerology (e.g., subcarrier spacing (SCS), transmission time interval (TTI) duration) may be differently configured between a plurality of cells aggregated for one UE. For example, if a UE is configured with different SCSs for cells aggregated for the cell, an (absolute time) duration of a time resource (e.g. a subframe, a slot, or a TTI) including the same number of symbols may be different among the aggregated cells. Herein, symbols may include OFDM symbols (or CP-OFDM symbols), SC-FDMA symbols (or discrete Fourier transform-spread-OFDM (DFT-s-OFDM) symbols). 
     Referring to  FIG. 7 , downlink and uplink transmissions are organized into frames. Each frame has Tf=10 ms duration. Each frame is divided into two half-frames, where each of the half-frames has 5 ms duration. Each half-frame consists of 5 subframes, where the duration Tsf per subframe is 1 ms. Each subframe is divided into slots and the number of slots in a subframe depends on a subcarrier spacing. Each slot includes 14 or 12 OFDM symbols based on a cyclic prefix (CP). In a normal CP, each slot includes 14 OFDM symbols and, in an extended CP, each slot includes 12 OFDM symbols. The numerology is based on exponentially scalable subcarrier spacing Δf=2u*15 kHz. The following table shows the number of OFDM symbols per slot, the number of slots per frame, and the number of slots per for the normal CP, according to the subcarrier spacing Δf=2u*15 kHz. 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                 u 
                 Nslotsymb 
                 Nframe, uslot 
                 Nsubframe, uslot 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 0 
                 14 
                 10 
                 1 
               
               
                   
                 1 
                 14 
                 20 
                 2 
               
               
                   
                 2 
                 14 
                 40 
                 4 
               
               
                   
                 3 
                 14 
                 80 
                 8 
               
               
                   
                 4 
                 14 
                 160 
                 16 
               
               
                   
                   
               
            
           
         
       
     
     The following table shows the number of OFDM symbols per slot, the number of slots per frame, and the number of slots per for the extended CP, according to the subcarrier spacing Δf=2u*15 kHz. 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                 u 
                 Nslotsymb 
                 Nframe, uslot 
                 Nsubframe, uslot 
               
               
                   
                   
               
             
            
               
                   
                 2 
                 12 
                 40 
                 4 
               
               
                   
                   
               
            
           
         
       
     
     A slot includes plural symbols (e.g., 14 or 12 symbols) in the time domain. For each numerology (e.g. subcarrier spacing) and carrier, a resource grid of Nsize,ugrid,x*NRBsc subcarriers and Nsubframe,usymb OFDM symbols is defined, starting at common resource block (CRB) Nstart,ugrid indicated by higher-layer signaling (e.g. radio resource control (RRC) signaling), where Nsize,ugrid,x is the number of resource blocks (RBs) in the resource grid and the subscript x is DL for downlink and UL for uplink. NRBsc is the number of subcarriers per RB. In the 3GPP based wireless communication system, NRBsc is 12 generally. There is one resource grid for a given antenna port p, subcarrier spacing configuration u, and transmission direction (DL or UL). The carrier bandwidth Nsize,ugrid for subcarrier spacing configuration u is given by the higher-layer parameter (e.g. RRC parameter). Each element in the resource grid for the antenna port p and the subcarrier spacing configuration u is referred to as a resource element (RE) and one complex symbol may be mapped to each RE. Each RE in the resource grid is uniquely identified by an index k in the frequency domain and an index 1 representing a symbol location relative to a reference point in the time domain. In the 3GPP based wireless communication system, an RB is defined by 12 consecutive subcarriers in the frequency domain. 
     In the 3GPP NR system, RBs are classified into CRBs and physical resource blocks (PRBs). CRBs are numbered from 0 and upwards in the frequency domain for subcarrier spacing configuration u. The center of subcarrier 0 of CRB 0 for subcarrier spacing configuration u coincides with ‘point A’ which serves as a common reference point for resource block grids. In the 3GPP NR system, PRBs are defined within a bandwidth part (BWP) and numbered from 0 to NsizeBWP,i−1, where i is the number of the bandwidth part. The relation between the physical resource block nPRB in the bandwidth part i and the common resource block nCRB is as follows: nPRB=nCRB+NsizeBWP,i, where NsizeBWP,i is the common resource block where bandwidth part starts relative to CRB 0. The BWP includes a plurality of consecutive RBs. A carrier may include a maximum of N (e.g., 5) BWPs. A UE may be configured with one or more BWPs on a given component carrier. Only one BWP among BWPs configured to the UE can active at a time. The active BWP defines the UE&#39;s operating bandwidth within the cell&#39;s operating bandwidth. 
     In the present disclosure, the term “cell” may refer to a geographic area to which one or more nodes provide a communication system, or refer to radio resources. A “cell” of a geographic area may be understood as coverage within which a node can provide service using a carrier and a “cell” as radio resources (e.g. time-frequency resources) is associated with bandwidth (BW) which is a frequency range configured by the carrier. The “cell” associated with the radio resources is defined by a combination of downlink resources and uplink resources, for example, a combination of a downlink (DL) component carrier (CC) and a uplink (UL) CC. The cell may be configured by downlink resources only, or may be configured by downlink resources and uplink resources. Since DL coverage, which is a range within which the node is capable of transmitting a valid signal, and UL coverage, which is a range within which the node is capable of receiving the valid signal from the UE, depends upon a carrier carrying the signal, the coverage of the node may be associated with coverage of the “cell” of radio resources used by the node. Accordingly, the term “cell” may be used to represent service coverage of the node sometimes, radio resources at other times, or a range that signals using the radio resources can reach with valid strength at other times. 
     In carrier aggregation (CA), two or more CCs are aggregated. A UE may simultaneously receive or transmit on one or multiple CCs depending on its capabilities. CA is supported for both contiguous and non-contiguous CCs. When CA is configured the UE only has one radio resource control (RRC) connection with the network. At RRC connection establishment/re-establishment/handover, one serving cell provides the non-access stratum (NAS) mobility information, and at RRC connection re-establishment/handover, one serving cell provides the security input. This cell is referred to as the Primary Cell (PCell). The PCell is a cell, operating on the primary frequency, in which the UE either performs the initial connection establishment procedure or initiates the connection re-establishment procedure. Depending on UE capabilities, Secondary Cells (SCells) can be configured to form together with the PCell a set of serving cells. An SCell is a cell providing additional radio resources on top of Special Cell. The configured set of serving cells for a UE therefore always consists of one PCell and one or more SCells. For dual connectivity operation, the term Special Cell (SpCell) refers to the PCell of the master cell group (MCG) or the PSCell of the secondary cell group (SCG). An SpCell supports PUCCH transmission and contention-based random access, and is always activated. The MCG is a group of serving cells associated with a master node, comprising of the SpCell (PCell) and optionally one or more SCells. The SCG is the subset of serving cells associated with a secondary node, comprising of the PSCell and zero or more SCells, for a UE configured with dual connectivity (DC). For a UE in RRC_CONNECTED not configured with CA/DC there is only one serving cell comprising of the PCell. For a UE in RRC_CONNECTED configured with CA/DC the term “serving cells” is used to denote the set of cells comprising of the SpCell(s) and all SCells. In DC, two MAC entities are configured in a UE: one for the MCG and one for the SCG. 
       FIG. 8  illustrates a data flow example in the 3GPP NR system. 
     In  FIG. 8 , “RB” denotes a radio bearer, and “H” denotes a header. Radio bearers are categorized into two groups: data radio bearers (DRB) for user plane data and signalling radio bearers (SRB) for control plane data. The MAC PDU is transmitted/received using radio resources through the PHY layer to/from an external device. The MAC PDU arrives to the PHY layer in the form of a transport block. 
     In the PHY layer, the uplink transport channels UL-SCH and RACH are mapped to their physical channels PUSCH and PRACH, respectively, and the downlink transport channels DL-SCH, BCH and PCH are mapped to PDSCH, PBCH and PDSCH, respectively. In the PHY layer, uplink control information (UCI) is mapped to PUCCH, and downlink control information (DCI) is mapped to PDCCH. A MAC PDU related to UL-SCH is transmitted by a UE via a PUSCH based on an UL grant, and a MAC PDU related to DL-SCH is transmitted by a BS via a PDSCH based on a DL assignment. 
     Data unit(s) (e.g. PDCP SDU, PDCP PDU, RLC SDU, RLC PDU, RLC SDU, MAC SDU, MAC CE, MAC PDU) in the present disclosure is(are) transmitted/received on a physical channel (e.g. PDSCH, PUSCH) based on resource allocation (e.g. UL grant, DL assignment). In the present disclosure, uplink resource allocation is also referred to as uplink grant, and downlink resource allocation is also referred to as downlink assignment. The resource allocation includes time domain resource allocation and frequency domain resource allocation. In the present disclosure, an uplink grant is either received by the UE dynamically on PDCCH, in a Random Access Response, or configured to the UE semi-persistently by RRC. In the present disclosure, downlink assignment is either received by the UE dynamically on the PDCCH, or configured to the UE semi-persistently by RRC signalling from the BS. 
       FIG. 9  shows an example of a discontinuous reception (DRX) operation to which technical feature of the present disclosure can be applied. 
     A UE may use DRX in order to reduce power consumption. A DRX cycle may be periodically recurred, and comprise a DRX ON duration (or, active duration/DRX active duration) in which the UE wakes up to monitor a PDCCH for the UE, and a DRX OFF duration (or, inactive duration/DRX inactive duration) in which the UE sleeps not to monitor a PDCCH for the UE. Since the DRX cycle is periodically recurred, the DRX ON duration and the DRX OFF duration may also be periodically recurred according to the DRX cycle. The DRX cycle may comprise a long DRX cycle and a short DRX cycle which are used in RRC_CONNECTED, and a paging DRX cycle which is used in RRC_IDLE and/or RRC_INACTIVE. The DRX in RRC_CONNECTED may be called ‘connected mode DRX (CDRX)’. 
     In RRC_CONNECTED, a UE may wake up to monitor a PDCCH for the UE (e.g., PDCCH addressed by C-RNTI) in a DRX ON duration of the long DRX cycle, and sleep not to monitor a PDCCH for the UE in a DRX OFF duration of the long DRX cycle. 
     If the UE receives a PDCCH for the UE in the DRX ON duration, the UE may start a DRX inactivity timer, and start/restart an RRC inactivity timer. The UE may, based on the PDCCH for the UE, receive DL data from a network, or transmit UL data to the network. 
     While the DRX inactivity timer is running, the UE may receive a PDCCH for the UE. In this case, the UE may restart the DRX inactivity timer and the RRC inactivity timer. The UE may, based on the PDCCH for the UE, receive DL data from a network, or transmit UL data to the network. 
     The DRX inactivity timer may expire if there is no PDCCH for the UE. If the DRX inactivity timer expires, the UE may start a DRX short cycle timer. While the DRX short cycle timer is running, the short DRX cycle may be periodically recurred. The UE may wake up to monitor a paging PDCCH for the UE (e.g., PDCCH addressed by P-RNTI) in a DRX ON duration of the short DRX cycle, and sleep not to monitor a PDCCH for the UE in a DRX OFF duration of the short DRX cycle. 
     If the DRX short cycle timer expires, the short DRX cycle may end, and the long DRX cycle may be periodically recurred. 
     If the RRC inactivity timer expires, the UE may enter RRC_IDLE or RRC_INACTIVE. The CDRX operation may end. 
     In RRC_IDLE (or, RRC_INACTIVE), a paging DRX operation may start. When the paging DRX operation is started, a paging DRX cycle may be periodically recurred. the UE may wake up to monitor a paging PDCCH for the UE (e.g., PDCCH addressed by P-RNTI) in a DRX ON duration of the paging DRX cycle, and sleep not to monitor a PDCCH for the UE in a DRX OFF duration of the paging DRX cycle. If the UE receives a paging PDCCH for the UE, the UE may receive a paging message in a PDSCH directed by the paging PDCCH, and perform an RRC connection establishment procedure. 
     The UE may monitor one paging occasion (PO) per paging DRX cycle. A PO is a set of PDCCH monitoring occasions and can consist of multiple time slots (e.g., subframe or OFDM symbol) where paging DCI can be sent. One paging frame (PF) may be on radio frame and may contain one or more POs or starting point of a PO. 
     In the above, the UE may be configured with at least one of the DRX cycle (e.g., long DRX cycle, short DRX cycle, paging DRX cycle, DRX ON duration and/or DRX OFF duration), DRX inactivity timer or DRX short cycle timer from a network. For example, the UE may receive, from the network, a DRX configuration comprising at least one of the long DRX cycle (e.g., longdrx-CycleStartOffset), the short DRX cycle, the paging DRX cycle, the DRX ON duration (e.g., onDurationTimer), DRX OFF duration, DRX inactivity timer or DRX short cycle timer. The UE may also be configured with the RRC inactivity timer from the network. 
     The UE may transmit UE assistance information to the network, to inform the network of a preference of the UE on DRX parameters for power saving. A UE capable of providing a preference of the UE on DRX parameters of a cell group for power saving in RRC_CONNECTED may transmit the UE assistance information in several cases, if the UE was configured to do so, including upon having a preference on DRX parameters and upon change of a preference of the UE on DRX parameters. 
     Upon initiating a procedure of transmitting the UE assistance information, the UE shall: 
     1&gt; if configured to provide its preference on DRX parameters of a cell group for power saving: 
     2&gt; if the UE has a preference on DRX parameters of the cell group and the UE did not transmit a UEAssistanceInformation message with drx-Preference for the cell group since it was configured to provide its preference on DRX parameters of the cell group for power saving; or 
     2&gt; if the current drx-Preference information for the cell group is different from the one indicated in the last transmission of the UEAssistanceInformation message including drx-Preference for the cell group and timer T 346   a  associated with the cell group is not running: 
     3&gt; start the timer T 346   a  with the timer value set to the drx-PreferenceProhibitTimer of the cell group; 
     3&gt; initiate transmission of the UEAssistanceInformation message to provide the current drx-Preference; 
     The UE shall set the contents of the UEAssistanceInformation message as follows: 
     1&gt; if transmission of the UEAssistanceInformation message is initiated to provide drx-Preference of a cell group for power saving: 
     2&gt; include drx-Preference in the UEAssistanceInformation message; 
     2&gt; if the UE has a preference on DRX parameters for the cell group: 
     3&gt; if the UE has a preference for the long DRX cycle: 
     4&gt; include preferredDRX-LongCycle in the DRX-Preference IE and set it to the preferred value; 
     3&gt; if the UE has a preference for the DRX inactivity timer: 
     4&gt; include preferredDRX-InactivityTimer in the DRX-Preference IE and set it to the preferred value; 
     3&gt; if the UE has a preference for the short DRX cycle: 
     4&gt; include preferredDRX-ShortCycle in the DRX-Preference IE and set it to the preferred value; 
     3&gt; if the UE has a preference for the short DRX timer: 
     4&gt; include preferredDRX-ShortCycleTimer in the DRX-Preference IE and set it to the preferred value; 
     2&gt; else (if the UE has no preference on DRX parameters for the cell group): 
     3&gt; do not include preferredDRX-LongCycle, preferredDRX-InactivityTimer, preferredDRX-ShortCycle and preferredDRX-ShortCycleTimer in the DRX-Preference IE. 
     The drx-Preference may comprise at least one of preferredDRX-InactivityTimer, preferredDRX-LongCycle, preferredDRX-ShortCycle or preferredDRX-ShortCycleTimer. 
     The preferredDRX-InactivityTimer may indicate the UE&#39;s preferred DRX inactivity timer length for power saving. If the preferredDRX-InactivityTimer is absent from the DRX-Preference information element (IE), it is interpreted as the UE having no preference for the DRX inactivity timer. 
     The may preferredDRX-LongCycle indicate the UE&#39;s preferred long DRX cycle length for power saving. If preferredDRX-ShortCycle is provided, the value of preferredDRX-LongCycle shall be a multiple of the preferredDRX-ShortCycle value. If the preferredDRX-LongCycle is absent from the DRX-Preference IE, it is interpreted as the UE having no preference for the long DRX cycle. 
     The preferredDRX-ShortCycle may indicate the UE&#39;s preferred short DRX cycle length for power saving. If the preferredDRX-ShortCycle is absent from the DRX-Preference IE, it is interpreted as the UE having no preference for the short DRX cycle. 
     The preferredDRX-ShortCycleTimer may indicate the UE&#39;s preferred short DRX cycle timer for power saving. If the preferredDRX-ShortCycleTimer is absent from the DRX-Preference IE, it is interpreted as the UE having no preference for the short DRX cycle timer. A preference for the short DRX cycle may be indicated when a preference for the short DRX cycle timer is indicated. 
     Hereinafter, contents related to a multi-universal subscriber identity module (MUSIM) is described. 
     Multi-USIM devices (e.g., MUSIM device  1010 ) have been more and more popular in different countries. The user may have both a personal and a business subscription in one device or have two personal subscriptions in one device for different services. 
       FIG. 10  shows an example of a wireless environment in which a MUSIM device operates according to an embodiment of the present disclosure. 
     Referring to  FIG. 10 , MUSIM device  1010  (or, MUSIM UE  1010 ) may have a plurality of universal subscriber identity modules (USIMs)—USIM 1   1011  (or, USIM_A  1011 ) and USIM 2   1013  (USIM_B  1013 ). The MUSIM device  1010  may register to a network  1   1020  based on subscription information in the USIM 1   1011  to obtain a connection A  1025  between the network  1   1020  and the MUSIM device  1010 . The MSUIM device  1010  may also register to a network  2   1030  based on subscription information in the USIM 2   1013  to obtain a connection B  1035  between the network  2   1030  and the MUSIM device  1010 . The MUSIM device  1010  may use the USIM 1   1011  to perform a communication with the network  1   1020  over the connection A  1025 , and use the USIM 2   1013  to perform a communication with the network  2   1030  over the connection B  1035 . 
     In a wireless environment in which a MUSIM device operates, the following properties may hold:
         Each registration from the USIMS of a MUSIM device may be handled independently.   Each registered USIM in the MUSIM device may be associated with a dedicated international mobile equipment identity (IMEI)/permanent equipment identifier (PEI).   A MUSIM UE may be connected with i) evolved packet system (EPS) on one USIM_And 5G system (5GS) on the other USIM; ii) EPS on both USIMs; or iii) 5GS on both USIMs.   A MUSIM UE may be a single reception (RX)/dual RX/single transmission (TX)/Dual TX UE. Single RX may allow the MUSIM UE to receive traffic from only one network at one time. Dual RX may allow the MUSIM UE to simultaneously receive traffic from two networks. Single TX may allow the MUSIM UE to transmit traffic to one network at one time. Dual TX may allow the MUSIM UE to simultaneously transmit traffic to two networks. The terms single RX/TX and Dual RX/TX do not refer to a device type. A single UE may, as an example, use Dual TX in some cases but Single TX in other case.   If/when the multiple USIMs in the MUSIM device are served by different serving networks, network coordination between the serving networks may not be required.   A MUSIM device with different USIMs may be camping with all USIMs on the same serving network RAN node, or the MUSIM device may be camping on different serving networks RAN nodes.   USIMs may belong to same or different operators. Coordination between involved operators may not be required.   USIM may be a physical SIM or embedded SIM (eSIM).       

     While actively communicating with a first system/network, a MUSIM UE may need to periodically monitor a second system/network (e.g. to synchronize, read the paging channel, perform measurements, or read the system information). The periodical activity on the second system may or may not have performance impact on the first system the UE is communicating with, depending on the UE implementation (i.e., single reception (Rx) or dual Rx). 
     In some cases, the UE equipped with different USIMs may have paging collisions which results in missed paging. When the UE receives a page in the second system while actively communicating with the first system, the UE may need to decide whether the UE should respond to this paging or not. When the UE decides to respond to the paging in the second system, the UE may need to stop the current activity in the first system. For example, the first system may suspend or release the ongoing connection with the UE. 
     For the multi-USIM UE, if USIM_A is in connected mode and USIM_B is in idle or RRC_INACTIVE mode, then the UE should be able to maintain RRC connection in USIM_A but may also be required to tune to USIM_B periodically to listen to paging. While the UE is absent from the network where USIM_A is camped, if the UE cannot receive DL data, it may result in waste of resources and degrade USIM_A connected mode performance, e.g., the RAN node for USIM_A may determine USIM_A has lost the traffic and reduce the scheduling rate. 
     The “scheduling gap” on USIM_A may be negotiated for the UE to tune away to USIM_B in order to listen to paging and then return to USIM_A. Since the tune away for listening paging happens periodically, the “scheduling gap” negotiated between the UE and RAN may be applied periodically. 
     USIM_A (i.e., UE in connected mode for USIM_A) may negotiate the “scheduling gap” with the served RAN node so the UE can tune away from USIM_A to perform the USIM_B procedures. For example, the USIM_A may transmit a request message for requesting a scheduling gap to the served RAN node. The request message may comprise at least one of a scheduling gap preferred by the USIM_A, or capability information of the USIM_A for the served RAN node to determine the scheduling gap. The served RAN node may transmit a response message for the request message to the USIM_A. The response message may comprise a scheduling gap determined by the served RAN node based on information included in the request message. That is, the response message may comprise a configuration related to the scheduling gap. 
     Meanwhile, a MUSIM UE may have concurrent registrations associated with several USIMs. While actively communicating with the system associated with one USIM (e.g., current system and/or first system), the MUSIM UE may determine that the MUSIM UE needs to perform some activity (e.g., respond to a paging, or perform mobility update) in the other system associated with other USIM(s) (e.g., the second system(s)). 
     To support activities in the other system associated with other USIM, a scheduling gap function may be used. The scheduling gap may be a duration that is configured/allowed by the current system i.e., the first system. Through the duration configured for the scheduling gap, the UE may pause the existing RRC connection on the current system and perform RRC procedures in the other system. 
     One potential problem for the scheduling gap is data interruption on the current system. This is because actual data would be scheduled for a duration excluding both times of scheduling gap and CDRX cycle. In other words, data in the current system would be scheduled by avoiding both the scheduling gap for the MUSIM operation and CDRX cycle. The idle period not transmitting data to the first system and/or receiving data from the first system can be increased as much as the increased duration that the scheduling gap isn&#39;t overlapped with the CDRX cycle if the scheduling gap and the CDRX cycle are separately considered. Thus, a mechanism may need to be considered to support the overlapped duration of both the scheduling gap and the CDRX cycle. As one of the mechanisms, DRX preference indication can be used not only for CDRX configuration but for scheduling gap configuration. 
     Furthermore, new information may be needed if the existing DRX preference indication is reused for asking the scheduling gap because the first system may not configure DRX parameters reflecting the UE&#39;s preference. That is, even if the UE transmits UE assistance information including CDRX preference information, the network may not configure (i.e., simply reject) the CDRX configuration according to the CDRX preference information. In this case, i.e., the system didn&#39;t provide/reflect the UE&#39;s preference on the DRX configuration, the UE may not perform SIM switching quickly from the first system to the second system due to lack of information for the scheduling gap. 
     According to various embodiments of the present disclosure, while performing MUSIM operation, to acquire the scheduling gap information, the UE may send to a first network on SIM_A an RRC message, e.g. UEAssistanceInformation message including DRX preference information. In the DRX preference information, the UE may set additional information, i.e., new information indicating that the UE will be absent from the first network on SIM_A to establish another RRC connection to the second network on SIM_B using DRX configuration. After sending the RRC message including the DRX preference information including the additional information, the UE may receive a DRX configuration from the first network. If the UE receives the DRX configuration, the UE may switch a (U)SIM operation from the first network on SIM_A to the second network on SIM_B during the inactive time/duration of the DRX cycle and perform necessary operations with/in the second network, such as paging monitoring, measurements, idle mode mobility operations, RRC connection establishment and/or data/signalling communication. While the UE performs the necessary operations in the second network, the UE may maintain the RRC connection with the first network. 
       FIG. 11  shows an example of a method performed by a UE according to an embodiment of the present disclosure. 
     Referring to  FIG. 11 , in step S 1101 , the UE may register to both a first network and a second network. 
     In step S 1103 , the UE may establish a connection with the first network. 
     In step S 1105 , the UE may transmit, to the first network, preference information related to a scheduling gap for the second network. The scheduling gap may be a duration in which the UE monitors a control channel from the second network. 
     In step S 1107 , the UE may receive, from the first network, a DRX configuration configuring an inactive duration of a DRX cycle for the first network to include the scheduling gap for the second network. The inactive duration of the DRX cycle for the first network may be a duration in which the UE does not monitor a control channel from the first network. The UE may apply the inactive duration of the DRX cycle for the first network in the DRX configuration. 
     In step S 1109 , the UE may perform operations with the second network during the inactive duration of the DRX cycle for the first network. 
     According to various embodiments of the present disclosure, the UE may be a multi-universal subscriber identity module (multi-USIM, MUSIM) UE equipped with a first USIM related to the first network and a second USIM related to the second network. The UE may register to the first network based on subscriber information in the first USIM. The UE may register to the second network based on subscriber information in the second USIM. 
     According to various embodiments of the present disclosure, the scheduling gap for the second network may be a duration in which the UE does not monitor a control channel from the first network in order to monitor a paging from the second network while the UE is a connected mode for the first network. For example, in the scheduling gap for the second network, the UE may absent from the first network in order to monitor a paging from the second network while the UE is a connected mode for the first network. For example, the UE may tune away from the first network to the second network, in order to monitor a paging from the second network while the UE is a connected mode for the first network. For example, the UE may perform a SIM switching from the first USIM to the second USIM, in order to monitor a paging from the second network while the UE is a connected mode for the first network. 
     According to various embodiments of the present disclosure, the preference information may inform that the UE prefers using the inactive duration of the DRX cycle for the first network as the scheduling gap for the second network. 
     According to various embodiments of the present disclosure, the preference information may inform a length of the scheduling gap for the second network required by the UE. 
     According to various embodiments of the present disclosure, the UE may transmit, to the first network, UE assistance information comprising the preference information. 
     According to various embodiments of the present disclosure, the DRX configuration may comprise information informing that the inactive duration of the DRX cycle for the first network is allowed to be used as the scheduling gap for the second network. 
     According to various embodiments of the present disclosure, the operations may comprise at least one of a paging monitoring, a measurement, mobility operations in idle mode, a connection establishment, a data communication or a signalling communication. 
     According to various embodiments of the present disclosure, the UE may perform the operations with the second network while maintaining the connection with the first network. 
     According to various embodiments of the present disclosure, the UE may perform the operations with the second network during the scheduling gap for the second network in the inactive duration of the DRX cycle for the first network without receiving, from the first network, a configuration related to the scheduling gap for the second network. 
     According to various embodiments of the present disclosure, an entire of the inactive duration of the DRX cycle for the first network may be used as the scheduling gap for the second network. 
     According to various embodiments of the present disclosure, the DRX configuration may comprise information for an entire duration of the DRX cycle and information for an active duration of the DRX cycle. The inactive duration of the DRX cycle and the scheduling gap may be determined as the entire duration of the DRX cycle minus the active duration of the DRX cycle. 
       FIG. 12  shows an example of a method performed by a BS in a first network according to an embodiment of the present disclosure. 
     Referring to  FIG. 12 , in step S 1201 , the BS may perform at least part of a procedure for registering a UE in the first network and a second network. 
     In step S 1203 , the BS may establish a connection with the UE. 
     In step S 1205 , the BS may receive, from the UE, preference information related to a scheduling gap for the second network. The scheduling gap for the second network may be a duration in which the UE monitors a control channel from the second network. 
     In step S 1207 , the BS may transmit, to the UE, a DRX configuration configuring an inactive duration of a DRX cycle for the first network to include the scheduling gap for the second network. The inactive duration of the DRX cycle for the first network may be a duration in which the UE does not monitor a control channel from the first network. 
     The BS in  FIG. 12  may be an example of a second device  220  in  FIG. 2 , and therefore, steps of the BS as illustrated in  FIG. 12  may be implemented by the second device  220 . For example, the processor  221  may be configured to perform at least part of a procedure for registering a UE in the first network and a second network. The processor  221  may be configured to establish a connection with the UE. The processor  221  may be configured to control the transceiver  223  to receive, from the UE, preference information related to a scheduling gap for the second network. The scheduling gap for the second network may be a duration in which the UE monitors a control channel from the second network. The processor  221  may be configured to control the transceiver  223  to transmit, to the UE, a DRX configuration configuring an inactive duration of a DRX cycle for the first network to include the scheduling gap for the second network. The inactive duration of the DRX cycle for the first network may be a duration in which the UE does not monitor a control channel from the first network. 
       FIG. 13  shows an example of a method for implementing CDRX based scheduling gap in MUSIM according to an embodiment of the present disclosure. 
     Referring to  FIG. 13 , in step S 1301 , the UE may initiate/perform an RRC connection establishment procedure with a network A on SIM_A. The UE may be in a non-connected mode (i.e., inactive/idle mode) for a network B on SIM_B. 
     The UE may be capable to support multiple-USIM operations, i.e., MUSIM operations. The UE may initiate the RRC connection establishment procedure to the network A on SIM_A. 
     In step S 1303 , the UE may send DRX preference information to the network A. The UE may be in connected mode for the network A, and non-connected mode for the network B. 
     To perform necessary operations in the network B, the UE may transmit an RRC message, e.g., UEAssistanceInformation message including the DRX preference information to the network A. For the DRX preference, the UE may set at least one of the below information as preferences in the preference information:
         preferredDRX-LongCycle: indicates the UE&#39;s preferred long DRX cycle length for power saving;   preferredDRX-InactivityTimer: indicates the UE&#39;s preferred DRX inactivity timer length for power saving;   preferredDRX-ShortCycle: indicates the UE&#39;s preferred short DRX cycle length for power saving;   preferredDRX-ShortCycleTimer: indicates the UE&#39;s preferred short DRX cycle timer for power saving;   preferredDRX-Purpose: indicates the UE&#39;s preferred purpose during the DRX cycle. As new information, the UE can indicate which operation is preferred by the DRX configuration among the scheduling gap and the legacy DRX. The preferredDRX-Purpose may be 1-bit information, e.g., if the preferredDRX-Purpose information is set to true or present, it means the UE wants to use the DRX configuration as the scheduling gap information for MUSIM operation. Else if the preferredDRX-Purpose information is set false or absent, it means the UE wants to update DRX configuration for power saving as the legacy procedure;   preferredDRX-MinlnactivePeriod: indicates the UE&#39;s preferred period of inactive (off) time of the preferred DRX cycle. Network (i.e., network A) may take the preferredDRX-MinInactivePeriod into account for UE scheduling and DRX command MAC CE to maximally ensure the preferred minimum inactive time; or   preferredDRX-Cycle-Offset: indicates the UE&#39;s preferred time offset that is applied to the currently configured DRX, represented by the number of subframes (or fixed time units). The value range of the preferredDRX-Cycle-Offset may include negative values and positive values. The UE may indicate the preferredDRX-Cycle-Offset to optimize/maximize the opportunities of performing necessary operations in the second network (i.e., network B).       

     The UE may need to evaluate the preferred DRX cycle and relevant parameters that are compliant with the necessary operations in network B. 
     In step S 1305 , the UE may receive a DRX configuration from network A. The UE may be in a connected mode for the network A on SIM_A, and non-connected mode for the network B on SIM_B. 
     After transmitting the DRX preference information to network A, the UE may receive an RRC message including a DRX configuration from the network A. In the DRX configuration, there may be one or more response information for the UE&#39;s DRX preference in the DRX configuration. The response information may indicate whether the DRX configuration is provided in response to the UE&#39;s DRX preference and/or whether the preferred DRX purpose is considered. For example, the response information may indicate that the network A allows to use of the DRX configuration for the scheduling gap. The response information may be 1-bit information. The response information may be reused as existing information. For example, if the response information is set to setup or true or present, it may mean that the DRX configuration is provided in response to the UE&#39;s preference including the new information. After applying the DRX configuration, the UE may monitor a paging from another network (i.e., network B) on SIM_B during the inactive time/duration of the DRX cycle. During the DRX cycle, the UE may maintain the RRC connection with the network A. 
     In step S 1307 , the UE may perform necessary operations on another network (i.e., network B) on SIM_B. The UE may be in a connected mode for the network A on SIM_A, and a connected mode for the network B on SIM_B. 
     During the inactive period/duration of the DRX cycle, the UE may perform at least one of the followings, if the inactive period/duration is acceptable for each of the followings:
         The UE may monitor paging information from network B. While monitoring paging information on the network B, the UE may receive a paging message from the network B;   The UE may perform measurements on network B based on the measurement information/configuration received from the network B;   The UE may perform idle mode mobility such as cell selection/reselection in network B;   The UE may receive system information in network B;   The UE may perform NAS signalling with network B;   The UE may perform RRC connection establishment with network B;   The UE may send or receive data in network B; and/or   The UE may send or receive control command including RRC message or L1/L2 control messages in network B.       

     In step S 1309 , the UE may send another DRX preference information to network A on SIM_A. The UE may be in a connected mode for the network A on SIM_A, and non-connected mode for the network B on SIM_B. 
     The UE may decide to transmit another DRX preference information via RRC signalling to request a longer/modified period of the scheduling gap because the UE needs to have an RRC connection on network B according to the paging. This is because the UE can send multiple DRX preference information to the network whenever the current period of the scheduling gap needs to be modified/updated. To establish an RRC connection on network B, the UE may transmit an RRC message, e.g., UEAssistanceInformation including DRX preference information to the network A. For the DRX preference, the UE may set the same type of information in step S 1303  with a different value but preferredDRX-Purpose is set to scheduling gap. 
     In step S 1311 , the UE may receive DRX configuration from network A on SIM_A. The UE may be in a connected mode for the network A on SIM_A, and a non-connected mode for the network B on SIM_B. 
     After transmitting another DRX preference information to network A, the UE may receive an RRC message including a DRX configuration from network A. The UE may also receive response information in the DRX configuration informing that network A allows to use the DRX configuration for scheduling gap. After applying the DRX configuration, the UE may send a request to establish an RRC connection on network B during the DRX cycle. 
     During the inactive period/duration of the DRX cycle, the UE may perform at least one of the followings:
         The UE may monitor paging information from network B. While monitoring paging information on the network B, the UE may receive a paging message from the network B;   The UE may perform measurements on network B based on the measurement information/configuration received from the network B;   The UE may perform idle mode mobility such as cell selection/reselection in network B;   The UE may receive system information in network B;   The UE may perform NAS signalling with network B;   The UE may perform RRC connection establishment with network B;   The UE may send or receive data in network B;   The UE may send or receive control command including RRC message or L1/L2 control messages in network B.       

       FIG. 14  shows a UE to implement an embodiment of the present disclosure. The present disclosure described above for UE side may be applied to this embodiment. The UE in  FIG. 14  may be an example of first device  210  as illustrated in  FIG. 2 . 
     A UE includes a processor  1410  (i.e., processor  211 ), a power management module  1411 , a battery  1412 , a display  1413 , a keypad  1414 , a subscriber identification module (SIM) card  1415 , a memory  1420  (i.e., memory  212 ), a transceiver  1430  (i.e., transceiver  213 ), one or more antennas  1431 , a speaker  1440 , and a microphone  1441 . 
     The processor  1410  may be configured to implement proposed functions, procedures and/or methods described in this description. Layers of the radio interface protocol may be implemented in the processor  1410 . The processor  1410  may include application-specific integrated circuit (ASIC), other chipset, logic circuit and/or data processing device. The processor  1410  may be an application processor (AP). The processor  1410  may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), a modem (modulator and demodulator). An example of the processor  1410  may be found in SNAPDRAGON™ series of processors made by Qualcomm®, EXYNOS™ series of processors made by Samsung®, A series of processors made by Apple®, HELIO™ series of processors made by MediaTek®, ATOM™ series of processors made by Intel® or a corresponding next generation processor. 
     The processor  1410  may be configured to, or configured to control the transceiver  1430  to implement steps performed by the UE and/or the wireless device throughout the disclosure. 
     The power management module  1411  manages power for the processor  1410  and/or the transceiver  1430 . The battery  1412  supplies power to the power management module  1411 . The display  1413  outputs results processed by the processor  1410 . The keypad  1414  receives inputs to be used by the processor  1410 . The keypad  1414  may be shown on the display  1413 . The SIM card  1415  is an integrated circuit that is intended to securely store the international mobile subscriber identity (IMSI) number and its related key, which are used to identify and authenticate subscribers on mobile telephony devices (such as mobile phones and computers). It is also possible to store contact information on many SIM cards. 
     The memory  1420  is operatively coupled with the processor  1410  and stores a variety of information to operate the processor  1410 . The memory  1420  may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium and/or other storage device. When the embodiments are implemented in software, the techniques described herein can be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The modules can be stored in the memory  1420  and executed by the processor  1410 . The memory  1420  can be implemented within the processor  1410  or external to the processor  1410  in which case those can be communicatively coupled to the processor  1410  via various means as is known in the art. 
     The transceiver  1430  is operatively coupled with the processor  1410 , and transmits and/or receives a radio signal. The transceiver  1430  includes a transmitter and a receiver. The transceiver  1430  may include baseband circuitry to process radio frequency signals. The transceiver  1430  controls the one or more antennas  1431  to transmit and/or receive a radio signal. 
     The speaker  1440  outputs sound-related results processed by the processor  1410 . The microphone  1441  receives sound-related inputs to be used by the processor  1410 . 
     According to various embodiments, the processor  1410  may be configured to, or configured to control the transceiver  1430  to implement steps performed by the UE and/or the wireless device throughout the disclosure. For example, the processor  1410  may be configured to register to both a first network and a second network. The processor  1410  may be configured to establish a connection with the first network. The processor  1410  may be configured to control the transceiver  1430  to transmit, to the first network, preference information related to a scheduling gap for the second network. The scheduling gap may be a duration in which the UE monitors a control channel from the second network. The processor  1410  may be configured to control the transceiver  1430  to receive, from the first network, a DRX configuration configuring an inactive duration of a DRX cycle for the first network to include the scheduling gap for the second network. The inactive duration of the DRX cycle for the first network may be a duration in which the UE does not monitor a control channel from the first network. The processor  1410  may be configured to apply the inactive duration of the DRX cycle for the first network in the DRX configuration. The processor  1410  may be configured to perform operations with the second network during the inactive duration of the DRX cycle for the first network. 
       FIG. 15  shows another example of a wireless communication system to which the technical features of the present disclosure can be applied. 
     Referring to  FIG. 15 , the wireless communication system may include a first device  1510  (i.e., first device  210 ) and a second device  1520  (i.e., second device  220 ). 
     The first device  1510  may include at least one transceiver, such as a transceiver  1511 , and at least one processing chip, such as a processing chip  1512 . The processing chip  1512  may include at least one processor, such a processor  1513 , and at least one memory, such as a memory  1515 . The memory may be operably connectable to the processor  1513 . The memory  1515  may store various types of information and/or instructions. The memory  1515  may store a software code  1515  which implements instructions that, when executed by the processor  1513 , perform operations of the first device  910  described throughout the disclosure. For example, the software code  1515  may implement instructions that, when executed by the processor  1513 , perform the functions, procedures, and/or methods of the first device  1510  described throughout the disclosure. For example, the software code  1515  may control the processor  1513  to perform one or more protocols. For example, the software code  1515  may control the processor  1513  to perform one or more layers of the radio interface protocol. 
     The second device  1520  may include at least one transceiver, such as a transceiver  1521 , and at least one processing chip, such as a processing chip  1522 . The processing chip  1522  may include at least one processor, such a processor  1523 , and at least one memory, such as a memory  1524 . The memory may be operably connectable to the processor  1523 . The memory  1524  may store various types of information and/or instructions. The memory  1524  may store a software code  1525  which implements instructions that, when executed by the processor  1523 , perform operations of the second device  1520  described throughout the disclosure. For example, the software code  1525  may implement instructions that, when executed by the processor  1523 , perform the functions, procedures, and/or methods of the second device  1520  described throughout the disclosure. For example, the software code  1525  may control the processor  1523  to perform one or more protocols. For example, the software code  1525  may control the processor  1523  to perform one or more layers of the radio interface protocol. 
     According to various embodiments, the first device  1510  as illustrated in  FIG. 15  may comprise a wireless device. The wireless device may comprise a transceiver  1511 , a processing chip  1512 . The processing chip  1512  may comprise a processor  1513 , and a memory  1515 . The memory  1515  may be operably connectable to the processor  1513 . The memory  1515  may store various types of information and/or instructions. The memory  1515  may store a software code  1515  which implements instructions that, when executed by the processor  1513 , perform operations comprising: registering to both a first network and a second network; establishing a connection with the first network; transmitting, to the first network, preference information related to a scheduling gap for the second network; receiving, from the first network, a discontinuous reception (DRX) configuration configuring an inactive duration of a DRX cycle for the first network to include the scheduling gap for the second network; applying the inactive duration of the DRX cycle for the first network in the DRX configuration; and performing operations with the second network during the inactive duration of the DRX cycle for the first network. The inactive duration of the DRX cycle for the first network may be a duration in which the UE does not monitor a control channel from the first network. The scheduling gap for the second network may be a duration in which the UE monitors a control channel from the second network. 
     According to various embodiments, a non-transitory computer-readable medium (CRM) may have stored thereon a plurality of instructions. The plurality of instructions, when executed by a processor of a UE, cause the UE to: register to both a first network and a second network; establish a connection with the first network; transmit, to the first network, preference information related to a scheduling gap for the second network; receive, from the first network, a discontinuous reception (DRX) configuration configuring an inactive duration of a DRX cycle for the first network to include the scheduling gap for the second network; apply the inactive duration of the DRX cycle for the first network in the DRX configuration; and perform operations with the second network during the inactive duration of the DRX cycle for the first network. The inactive duration of the DRX cycle for the first network may be a duration in which the UE does not monitor a control channel from the first network. The scheduling gap for the second network may be a duration in which the UE monitors a control channel from the second network. 
     The present disclosure may be applied to various future technologies, such as AI, robots, autonomous-driving/self-driving vehicles, and/or extended reality (XR). 
     &lt;AI&gt; 
     AI refers to artificial intelligence and/or the field of studying methodology for making it. Machine learning is a field of studying methodologies that define and solve various problems dealt with in AI. Machine learning may be defined as an algorithm that enhances the performance of a task through a steady experience with any task. 
     An artificial neural network (ANN) is a model used in machine learning. It can mean a whole model of problem-solving ability, consisting of artificial neurons (nodes) that form a network of synapses. An ANN can be defined by a connection pattern between neurons in different layers, a learning process for updating model parameters, and/or an activation function for generating an output value. An ANN may include an input layer, an output layer, and optionally one or more hidden layers. Each layer may contain one or more neurons, and an ANN may include a synapse that links neurons to neurons. In an ANN, each neuron can output a summation of the activation function for input signals, weights, and deflections input through the synapse. Model parameters are parameters determined through learning, including deflection of neurons and/or weights of synaptic connections. The hyper-parameter means a parameter to be set in the machine learning algorithm before learning, and includes a learning rate, a repetition number, a mini batch size, an initialization function, etc. The objective of the ANN learning can be seen as determining the model parameters that minimize the loss function. The loss function can be used as an index to determine optimal model parameters in learning process of ANN. 
     Machine learning can be divided into supervised learning, unsupervised learning, and reinforcement learning, depending on the learning method. Supervised learning is a method of learning ANN with labels given to learning data. Labels are the answers (or result values) that ANN must infer when learning data is input to ANN. Unsupervised learning can mean a method of learning ANN without labels given to learning data. Reinforcement learning can mean a learning method in which an agent defined in an environment learns to select a behavior and/or sequence of actions that maximizes cumulative compensation in each state. 
     Machine learning, which is implemented as a deep neural network (DNN) that includes multiple hidden layers among ANN, is also called deep learning. Deep learning is part of machine learning. In the following, machine learning is used to mean deep learning. 
       FIG. 16  shows an example of an AI device to which the technical features of the present disclosure can be applied. 
     The AI device  1600  may be implemented as a stationary device or a mobile device, such as a TV, a projector, a mobile phone, a smartphone, a desktop computer, a notebook, a digital broadcasting terminal, a PDA, a PMP, a navigation device, a tablet PC, a wearable device, a set-top box (STB), a digital multimedia broadcasting (DMB) receiver, a radio, a washing machine, a refrigerator, a digital signage, a robot, a vehicle, etc. 
     Referring to  FIG. 16 , the AI device  1600  may include a communication part  1610 , an input part  1670 , a learning processor  1630 , a sensing part  1640 , an output part  1650 , a memory  1660 , and a processor  1670 . 
     The communication part  1610  can transmit and/or receive data to and/or from external devices such as the AI devices and the AI server using wire and/or wireless communication technology. For example, the communication part  1610  can transmit and/or receive sensor information, a user input, a learning model, and a control signal with external devices. The communication technology used by the communication part  1610  may include a global system for mobile communication (GSM), a code division multiple access (CDMA), an LTE/LTE-A, a 5G, a WLAN, a Wi-Fi, Bluetooth™, radio frequency identification (RFID), infrared data association (IrDA), ZigBee, and/or near field communication (NFC). 
     The input part  1670  can acquire various kinds of data. The input part  1670  may include a camera for inputting a video signal, a microphone for receiving an audio signal, and a user input part for receiving information from a user. A camera and/or a microphone may be treated as a sensor, and a signal obtained from a camera and/or a microphone may be referred to as sensing data and/or sensor information. The input part  1670  can acquire input data to be used when acquiring an output using learning data and a learning model for model learning. The input part  1670  may obtain raw input data, in which case the processor  1670  or the learning processor  1630  may extract input features by preprocessing the input data. 
     The learning processor  1630  may learn a model composed of an ANN using learning data. The learned ANN can be referred to as a learning model. The learning model can be used to infer result values for new input data rather than learning data, and the inferred values can be used as a basis for determining which actions to perform. The learning processor  1630  may perform AI processing together with the learning processor of the AI server. The learning processor  1630  may include a memory integrated and/or implemented in the AI device  1600 . Alternatively, the learning processor  1630  may be implemented using the memory  1660 , an external memory directly coupled to the AI device  1600 , and/or a memory maintained in an external device. 
     The sensing part  1640  may acquire at least one of internal information of the AI device  1600 , environment information of the AI device  1600 , and/or the user information using various sensors. The sensors included in the sensing part  1640  may include a proximity sensor, an illuminance sensor, an acceleration sensor, a magnetic sensor, a gyro sensor, an inertial sensor, an RGB sensor, an IR sensor, a fingerprint recognition sensor, an ultrasonic sensor, an optical sensor, a microphone, a light detection and ranging (LIDAR), and/or a radar. 
     The output part  1650  may generate an output related to visual, auditory, tactile, etc. The output part  1650  may include a display unit for outputting visual information, a speaker for outputting auditory information, and/or a haptic module for outputting tactile information. 
     The memory  1660  may store data that supports various functions of the AI device  1600 . For example, the memory  1660  may store input data acquired by the input part  1670 , learning data, a learning model, a learning history, etc. 
     The processor  1670  may determine at least one executable operation of the AI device  1600  based on information determined and/or generated using a data analysis algorithm and/or a machine learning algorithm. The processor  1670  may then control the components of the AI device  1600  to perform the determined operation. The processor  1670  may request, retrieve, receive, and/or utilize data in the learning processor  1630  and/or the memory  1660 , and may control the components of the AI device  1600  to execute the predicted operation and/or the operation determined to be desirable among the at least one executable operation. The processor  1670  may generate a control signal for controlling the external device, and may transmit the generated control signal to the external device, when the external device needs to be linked to perform the determined operation. The processor  1670  may obtain the intention information for the user input and determine the user&#39;s requirements based on the obtained intention information. The processor  1670  may use at least one of a speech-to-text (STT) engine for converting speech input into a text string and/or a natural language processing (NLP) engine for acquiring intention information of a natural language, to obtain the intention information corresponding to the user input. At least one of the STT engine and/or the NLP engine may be configured as an ANN, at least a part of which is learned according to a machine learning algorithm. At least one of the STT engine and/or the NLP engine may be learned by the learning processor  1630  and/or learned by the learning processor of the AI server, and/or learned by their distributed processing. The processor  1670  may collect history information including the operation contents of the AI device  1600  and/or the user&#39;s feedback on the operation, etc. The processor  1670  may store the collected history information in the memory  1660  and/or the learning processor  1630 , and/or transmit to an external device such as the AI server. The collected history information can be used to update the learning model. The processor  1670  may control at least some of the components of AI device  1600  to drive an application program stored in memory  1660 . Furthermore, the processor  1670  may operate two or more of the components included in the AI device  1600  in combination with each other for driving the application program. 
       FIG. 17  shows an example of an AI system to which the technical features of the present disclosure can be applied. 
     Referring to  FIG. 17 , in the AI system, at least one of an AI server  1720 , a robot  1710   a , an autonomous vehicle  1710   b , an XR device  1710   c , a smartphone  1710   d  and/or a home appliance  1710   e  is connected to a cloud network  1700 . The robot  1710   a , the autonomous vehicle  1710   b , the XR device  1710   c , the smartphone  1710   d , and/or the home appliance  1710   e  to which the AI technology is applied may be referred to as AI devices  1710   a  to  1710   e.    
     The cloud network  1700  may refer to a network that forms part of a cloud computing infrastructure and/or resides in a cloud computing infrastructure. The cloud network  1700  may be configured using a 3G network, a 4G or LTE network, and/or a 5G network. That is, each of the devices  1710   a  to  1710   e  and  1720  consisting the AI system may be connected to each other through the cloud network  1700 . In particular, each of the devices  1710   a  to  1710   e  and  1720  may communicate with each other through a base station, but may directly communicate with each other without using a base station. 
     The AI server  1720  may include a server for performing AI processing and a server for performing operations on big data. The AI server  1720  is connected to at least one or more of AI devices constituting the AI system, i.e. the robot  1710   a , the autonomous vehicle  1710   b , the XR device  1710   c , the smartphone  1710   d  and/or the home appliance  1710   e  through the cloud network  1700 , and may assist at least some AI processing of the connected AI devices  1710   a  to  1710   e . The AI server  1720  can learn the ANN according to the machine learning algorithm on behalf of the AI devices  1710   a  to  1710   e , and can directly store the learning models and/or transmit them to the AI devices  1710   a  to  1710   e . The AI server  1720  may receive the input data from the AI devices  1710   a  to  1710   e , infer the result value with respect to the received input data using the learning model, generate a response and/or a control command based on the inferred result value, and transmit the generated data to the AI devices  1710   a  to  1710   e . Alternatively, the AI devices  1710   a  to  1710   e  may directly infer a result value for the input data using a learning model, and generate a response and/or a control command based on the inferred result value. 
     Various embodiments of the AI devices  1710   a  to  1710   e  to which the technical features of the present disclosure can be applied will be described. The AI devices  1710   a  to  1710   e  shown in  FIG. 17  can be seen as specific embodiments of the AI device  1600  shown in  FIG. 16 . 
     The present disclosure can have various advantageous effects. 
     For example, the unnecessary duration can be reduced by configuring overlapped duration for CDRX and the scheduling gap so that more efficient data scheduling is possible for MUSIM UE. Also, since the UE sends the network new information indicating a preference that the DRX is used for the scheduling gap, the network can provide the UE&#39;s preference on the DRX configuration without rejection to support quick SIM switching. 
     Advantageous effects which can be obtained through specific embodiments of the present disclosure are not limited to the advantageous effects listed above. For example, there may be a variety of technical effects that a person having ordinary skill in the related art can understand and/or derive from the present disclosure. Accordingly, the specific effects of the present disclosure are not limited to those explicitly described herein, but may include various effects that may be understood or derived from the technical features of the present disclosure. 
     In view of the exemplary systems described herein, methodologies that may be implemented in accordance with the disclosed subject matter have been described with reference to several flow diagrams. While for purposed of simplicity, the methodologies are shown and described as a series of steps or blocks, it is to be understood and appreciated that the claimed subject matter is not limited by the order of the steps or blocks, as some steps may occur in different orders or concurrently with other steps from what is depicted and described herein. Moreover, one skilled in the art would understand that the steps illustrated in the flow diagram are not exclusive and other steps may be included or one or more of the steps in the example flow diagram may be deleted without affecting the scope of the present disclosure. 
     Claims in the present description can be combined in a various way. For instance, technical features in method claims of the present description can be combined to be implemented or performed in an apparatus, and technical features in apparatus claims can be combined to be implemented or performed in a method. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in an apparatus. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in a method. Other implementations are within the scope of the following claims.